1. FIELD OF THE INVENTION
This invention relates generally to connective mechanical joints;
and more particularly to a joint that permits relative rotation of interconnected
articles -- through large angles, and about an axis having virtually any arbitrarily
selectable orientation. The joint can be made to transmit a force or a flux (electrical,
optical or fluid) between the articles.
In the IBM Technical Disclosure Bulletin, vol. 17, no. 9, February
1975, New York, USA, page 2816, a connective joint for interconnecting two articles
for controlled relative motion is disclosed. This joint comprises a pair of interlocking
stationary rings, whereby each ring is attached to one of the articles. The inner
surface of one stationary ring is secured to the outer surface of the other ring.
Because of this connection the stem of one of the rings is secured to an outer
movable ring and the stem of the other ring is secured to an inner movable ring.
Because one of the stems must be secured to an inner ring a bracket is required
extending over the outer stationary ring to permit movement of the stem. Because
of the manner in which the rings are secured to one another they must be of different
diameters. Furthermore, this known connective joint cannot be symmetrical.
Known connective joints may be considered in three very broad categories:
the hinge, which provides large-amplitude rotation between two hinged elements,
but only about a single axis; the ball-and-socket joint, which provides rotation
about arbitrarily selectable axes, but usually with limited range of rotation;
and the universal joint, which is in effect a two-stage hinge.
Both large-amplitude rotation and a wide range of rotational axes
are achieved with a universal joint by combining two hinges in series, generally
at right angles. The selection of rotational axes is essentially arbitrary if
rotation is permitted about one or both points of attachment of articles to the
universal joint -- for example, if the articles interconnected by the joint are
With a ball joint, rotational range is particularly limited when
a fluid flux is to be transmitted across the joint -- as, for example, in a liquid-transmitting
joint such as a shower head.
In two different senses, torque can be transmitted through a hinge
or universal joint. First, an article attached to one side of the joint can be
rotated by rotating an article attached to the other side of the joint -- provided
that the rotation is about an axis on which the hinge or universal joint is not
(The availability of such an axis for useful purposes depends upon
the relative orientation of the two sides of the joint. For example, suppose that
the two articles are drive shafts, but the joint is initially operated or set
so that these shafts are mutually at right angles. Now rotation of either of the
two shafts about its own axis can be transmitted through the joint to the other,
but of course the resulting rotation of the receiving shaft is not about its own
Force or torque can also be transmitted through a hinge or universal
joint in a second sense. For such transmission, a gear or a traction surface is
provided on an article at one side of the joint, and a suitably mating drive gear
or traction wheel is provided on an article at the other side of the joint. With
this arrangement, forcible rotation of the gear or wheel results in operation
of the joint itself -- i. e., change of the relative angle (or angles) at
which the two articles are joined.
In the prior art, it has not been readily feasible to interconnect
articles for rotation through large angles about a virtually arbitrary axis, using
a single-stage joint. Such connection has been particularly awkward with transmission
of force or a flux across the joint.
In its simplest forms, the invention disclosed in my two above-listed
previous applications may be very roughly conceptualized as a particularly efficient
single-stage hinge, in which there is no separate hinge pin as such. Instead,
each side or element of the hinge can itself serve as the hinge pin, entering
or leaving this role at the pleasure of the user.
Even though this "hinge" has only one stage, its two sides or elements
pivot about different axes, thereby permitting operation of the hinge about virtually
any axis the user selects. Consequently this single-stage hinge is free to rotate
in as many different directions, roughly speaking, as a universal joint. Furthermore,
being a hinge rather than a ball joint, it operates through a very wide angular
Alternatively, and curiously, that earlier invention can be very
roughly conceptualized as a hinge in which everything except the hinge pin has
been eliminated -- but there are two hinge pins, each rolled or wrapped
around the other in an endless ring, to permit operation of the hinge in virtually
These informal conceptualizations of the invention of my previous
applications may seem contradictory and slightly baffling, but as made clear in
those applications both conceptualizations are reasonably accurate. That invention
is based upon the concept of interlocking bodies -- with, in most embodiments,
each body rotating upon its own axis, and each rotating through and around the
other body. For some purposes, as described in my previous applications, a common
internal structure can be provided for transmission of a force or a flux through
all or part of the joint.
In some preferred embodiments emphasized in my previous applications,
each body is a toroid in the relatively strict sense of having a circular minor
cross-section. It is this property that allows each body to serve as a "hinge
pin" for the other body -- particularly if, as in some preferred embodiments, each
body fits closely around the circular minor cross-section of the other body. These
properties also serve to conceal the common internal structure, if desired, so
that the capability of the joint for transmission of force or flux appears unaccountable
to a casual observer.
One result, however, is that the bodies fit together relatively tightly,
leaving relatively little open space for flux-transmitting interconnections within
the common internal structure of the joint, and therefore militating in favor
of very compact slip-rings, brushes, or sliding tubing connections for transmission
of force or flux through the joint. These types of transmission components are
subject to wear, and also are relatively expensive to make and assemble.
My previous invention, accordingly, does leave some room for refinement
in the practical areas of economy and durability -- particularly for those uses
in which concealment of the existence of a common internal structure is not particularly
Another joint that is related to my invention has been described
by Mark E. Rosheim, in Robot Wrist Actuators (Wiley Interscience Publications,
1989) at pages 213 through 218. Rosheim's device incorporates two interlocking
rings, each rotatable about its own axis, and about and through the other ring
-- being guided in such rotation by a semicircular arcuate guiding structure.
Each of the two rings is driven by a hydraulic piston and cylinder,
which are respectively integral with
the ring and its guide surface. More
specifically, each ring itself defines a circular piston rod, mounted along
which is a laterally (that is, radially) extending vane or paddle that serves
as a piston. In general this piston seemingly could be of arbitrary cross-section,
but Rosheim illustrates a rectangular piston.
The circular piston rod passes through seals at both ends of a semicircular
hydraulic chamber that serves as the cylinder. The piston slides within
this chamber, making a sliding seal with the chamber walls.
Hydraulic fluid is introduced controllably and selectably into either
end of the chamber, to drive the piston along the chamber, and thereby rotate the
circular piston rod (i. e., one of the two interlocking rings), in either
direction respectively. The Rosheim system is intrinsically limited in maximum
rotational range by impingement of the piston upon the two internal end
walls of the semicircular chamber. In principle, although Rosheim does not say
so, this limitation considered alone could be obviated by extending the chamber
from semicircular to nearly circular.
In normal or typical use, however, as Rosheim shows, some stem or
other mounting element must protrude from the piston-rod/ring, outside the chamber,
for attachment of a tool or working head to be positioned by the joint. In such
practical cases, the Rosheim system is also limited in maximum rotational range
by impingement of this stem upon the two external end walls of the chamber.
If the first limitation considered above were obviated by increasing
the.angular extent of the chamber beyond semicircular, the result would be to make
this second limitation evem more stringent. That is, the sum of the angular ranges
of the two objects rotating with the piston rod (the piston inside the chamber,
and the stem outside) can only be slightly less than a full circle; so the maximum
range of each can only be slightly less than a semicircle.
Rosheim does not articulate these limitations; even if he were to
recognize them, however, at least no minor modification of his hydraulic system
could circumvent them. In particular, because Rosheim's piston-and-chamber combination
itself integrally supplies the guiding surfaces for arcuate motion of the
ring, the piston rotational range cannot readily be increased by merely removing
the piston or chamber from his finished device and driving the ring rotation in
some other way.
In addition, the Rosheim device -- while very simple and elegant
in principle -- is clearly an expensive and difficult article to manufacture. It
depends for its effectiveness upon two sliding seals at the ends of the chamber
and a piston seal that slides along the chamber interior walls.
The semicircular chamber walls and the entire ring (the circular
piston rod) must be made and maintained smooth enough for trouble-free operation
of these sliding seals. This is a rather severe condition for most practical devices:
nearly the entire length of the ring (only excepting the segments subtended by
the end seals) is outside the chamber at one time or another, exposed to the possibility
of scrapes or dents that could interfere with sealing motion.
Furthermore, Rosheim's main illustrations (Figs. 6.10 through 6.13)
show that the necessary tube fittings, for supplying hydraulic liquid to drive
his joint, are routed outside his mechanism, rather than through it. No
connections pass through the first-stage stem and ring into the inner structure.
Even in the version of Rosheim's device with so-called "internal
porting" (shown in his Figs. 6.19 and 6.20, and discussed at page 219), no connections
pass through the first-stage stem and ring into the inner structure. Instead,
an entirely separate hydraulic-line yoke provides entry to the central structure
through pivoting seals, outboard along the axis of the first stage; and still
the valve-control electrical cables appear to be routed outside the joint.
All this is entirely understandable, since connection of tubing or
wires between Rosheim's hydraulic drive-and-guide structure and his sealingly smooth
rings or piston would be extremely difficult if not entirely impractical. It also
would render his device even more drastically cumbersome and uneconomic.
For multiple fluid, optical or electrical fluxes, true through-routing
(passing through the first-stage stem and ring into the inner structure) would
probably be simply prohibitive. It is accordingly fair to assume that external
routing would be used for also conveying fluid or electricity across the joint,
from the mounting stem to the working-head stem, in installations requiring use
or delivery of fluid or electricity at the working head.
Rosheim's external routing of tubes or wires, however, presents important
additional drawbacks. In his basic design with external hydraulic-line routing,
the tubulations are subject to entanglement, in the course of compound motion
of the joint. In joints that are used to convey a flux of fluid, light or electricity
for use or delivery at the working head, in addition to using hydraulic or electrical
signals to operate the joint itself, the entanglement problem will be compounded.
(Inasmuch as each stage of his joint is capable of rotation only through a half-circle,
this hazard may not manifest itself as a major problem in his device; but
in the context of joints that provide much wider angular rotation, such as my
prior and present inventions, it would be most troublesome.)
Further, many automatically operated joints must function under highly
restrictive environments that may include high temperatures, welding flames or
arcs, nearby fast-moving machinery, and so forth. These are all capable of severing
or otherwise damaging uncontrolled loose wires or tubing.
As to Rosheim's design with "internal porting" there are several
adverse consequences: the added complexity and bulkiness, and the two additional
moving seals far outboard, are all highly undesirable; even if the first-stage
hydraulic chamber itself did not obstruct travel of the second-stage stem, the
additional hydraulic-line yoke certainly would; and as noted above, Rosheim's
illustrations appear to indicate that his electrical wires would remain routed
outside the joint even in the internally ported device. Finally, his already unsatisfactory
"internal porting" solution would escalate in difficulty, cost and unreliability
with addition of multiple fluxes for delivery or use at the working head.
In fact, Rosheim's stated motivation in putting the control valves
on board the joint is to avoid "sponginess" in control, and thereby to preserve
reliability and response time. He does not even suggest that it would be desirable
to move tubulations (or wires) inside the joint for the purpose of eliminating
rotating seals and contacts as well as exposed and possibly tangled tubes and
Accordingly Rosheim does not effectively supply the above-suggested
refinement of my earlier invention, in regard to economy and durability -- particularly
for industrial or other practical uses that impose little demand upon the esthetics
of the internal guide structure.
It appears that the Rosheim publication is not prior art with respect
to at least some forms of the present invention. Further, although Rosheim asserts
that he invented his hydraulic wrist in 1980, none of his now-issued patents discloses
SUMMARY OF THE DISCLOSURE
Before offering any relatively rigorous definition, I shall present
some very informal Preliminary comments. These may help to orient the reader to
the more formally worded passages and the details that follow.
The present document is directed to adaptations, simplifications,
refinements and in some instances simply applications of my earlier interlocking-bodies
joint. These are particularly (but not exclusively) suited for utilitarian functions
in which it is not necessary or desired to conceal an internal guide structure;
or in which the circular cross-sections of the toroids emphasized in my above-mentioned
earlier patent applications are not of interest.
The refinements, applications and adaptations that are first disclosed
here permit use of flexible wires, optic fibers or tubing running directly through
connection stems and interlocking outer structures, into inner structures that
guide the interlocking outer structures in systematic mutual movement. These flexible
wires, fibers or tubes transmit electrical, optical or fluid fluxes either to
utilization devices mounted on or in the internal structure (to drive or control
the joint, for example), or entirely across the joint for use or delivery at the
working head or otherwise.
The use of such flexible flux-transmission means is made possible
in my invention by employing inner structures that are amenable to defining a sizable
central hollow or cavity. The flexible wires, fibers or tubes simply bend, twist,
stretch or otherwise deform within the central cavity, thereby accommodating operation
through very large angles -- and even several complete rotations, with appropriate
production design -- even though the wires, fibers or tubes are entirely conventional
Remarkably, the inner structures of my invention that permit these
advantageous inner features can take any of a great variety of simple, inexpensive
forms, all very easily made and assembled in any general-purpose workshop. In
the following pages I shall describe several specific forms that I personally prefer,
but in addition I shall point out how the specific form actually employed can
be virtually arbitrary, as long as certain critical but very simple guide surfaces
In my devices, even with a protruding stem, each stage can typically
rotate through nearly an entire circle. In usages not requiring a protruding stem,
each stage can rotate through even much larger angles. This property of my invention
is of very great value in industrial and other practical use.
In my invention, the joint can be driven by motors, which can be
electrical motors, or airmotors, or hydraulically driven motors. The motors are
preferably discrete with respect to the major elements of the joint --
that is to say, they are not integrated into the rotating body and constraining
structure as are Rosheim's drive units. Because my motors are discrete, they can
be conveniently positioned in any of a great variety of different positions and
orientations, and as will be seen do not obstruct the motion of the joint through
the very large angular rotations just mentioned.
For example, one of my motors can be mounted in a connecting stem
(which of course rotates with one of the moving bodies), to drive a ring gear that
is mounted to the constraining structure. This arrangement is shown and discussed
in my above-mentioned earlier patent applications (Fig. 20 and associated text).
Equivalently, a motor can be positioned elsewhere in the rotating
body to drive such a ring gear, or mounted on the constraining structure to drive
a ring gear that is mounted to the rotating body. These latter two configurations
are disclosed in greater detail below.
With the foregoing informal introduction, I shall now offer a somewhat
more rigorous statement. My invention is a connective joint for interconnecting
two articles for controlled relative motion.
For present purposes the word "article" is used in a quite broad
sense. As to one side of the joint, this word encompasses an article such as the
earth, or pavement on the ground; or a solid building, structure, floor or base
-- to any of which one side of the joint may be mounted.
In a preferred form, my invention includes a pair of interlocking
bodies. By "interlocking" I mean mutually interlocked -- that is to say, passing
through and around each other. (I do not mean to imply that the bodies are
necessarily secured together in such a way as to preclude ready separation, although
this is likely to be so in most typical cases.)
Simply as a matter of semantics, this condition necessarily requires
that each body have some minimal form that is capable of having another body pass
through and around it. This condition also necessarily requires that each body
be capable of passing through and around another body.
Two circular rings of course satisfy this condition, if the relationships
between the cross-sections and central holes of the rings are suitable. For purposes
of satisfying this condition, however, circular rings represent an extreme case
of geometric regularity.
A body of my invention need not be strictly circular, or indeed generally
arcuate, or even very regular, or even a completely closed shape -- provided only
that it does in common understanding define (1) enough of an encircling form as
to pass around another body, and (2) enough of an enclosing form as to be passed
through by another body. The latter limitation may also be expressed by saying
that the body must define a hole; however, still as in common understanding, an
opening need not be completely surrounded by material to answer to the description
of a "hole".
My invention also includes some means for attaching each of the bodies
to one of such "articles" respectively. For purposes of generality in expression,
I shall refer to these means as the "attaching means."
My invention also includes a structure constraining the bodies for
systematic relative movement.
The foregoing may be a definition of my invention in its broadest
or most general form. In fact, this definition is broader than those set forth
in my earlier patent applications (and is based exclusively upon the disclosure
of my earlier applications) -- which may be well understood, in that the present
document is devoted, as mentioned above, to utilitarian uses in which certain
earlier constraints are relaxed or eliminated.
I prefer, however, to practice my invention with several additional
features or properties. These added characteristics operate to enhance or optimize
enjoyment of the maximum benefits of the invention.
For example, a preferred form of my invention also includes some
means for applying mechanical force and power to drive the bodies in the systematic
relative movement mentioned above. Again for generality, these means may be referred
to as the "applying means".
As another example, a preferred form of the invention also includes
some means for transmitting a flux between one of the articles and the constraining
structure -- once again, the "flux-transmitting means". By "flux" as in my earlier
patent applications I refer to a flux of electricity or of fluid (either liquid
or gas); and an optical flux as well.
Any such type of flux may be transmitted only partway across the
joint, as for example to operate the joint itself -- that is, may drive "applying
means" or a portion thereof. Alternatively, either type of flux may be transmitted
entirely across the joint, from a flux source associated with one of the attaching
means to some flux-utilization device or flux-delivery device associated with
another of the attaching means.
These flux-transmitting means preferably transmit the flux by way
of the attaching means. As will be seen, the constraining structure of my invention
can be engaged with the interlocking bodies in such a way that flux can be transmitted
between either article (or both articles) and the constraining structure -- without
interfering with reasonably free motion of the bodies upon the constraining structure.
The flux-transmitting means, in fact, advantageously take the form
of flexible means -- such as wires, optic fibers or tubes -- for carrying the electricity,
light or fluid. These flexible elements preferably pass through the constraining
structure, in a hollow cavity formed within that structure, and within and protruding
from attachment points along the bodies.
In yet another preferred form of the invention, which may be incorporated
with those just discussed, the constraining structure includes four guides arranged
in pairs. A part of each guide defines a track, part of which is shaped substantially
as a portion of a circle; and each guide also defines a cutout slot extending
within the circular part of the track.
In this form of the invention the two tracks of each pair are mutually
substantially parallel (though not necessarily of the same diameter), and the circular
track parts are substantially conaxial. By "conaxial" I mean aligned along a common
axis, though not necessarily in a common plane. The two pairs of guides are interfitted
so that the slots in each pair mutually engage the slots in, and the surfaces
of, the other pair.
The interfitted pairs of spaced-apart guides form a substantially
hollow enclosure -- for passage of flexible flux-transmission means from at least
one of the bodies. Each pair of tracks engages one of the two bodies respectively,
for rotational motion of the bodies relative to the tracks.
In this way the guides define two mutually fixed pairs of tracks.
The result is that, in the relative motion mentioned earlier, the two bodies both
rotate about the hollow enclosure.
In another preferred form of the invention, the constraining structure
takes a notably different form from that just discussed, and engages the interlocking
bodies in a different way. Here each body defines a pair of axially spaced-apart
circular followers; and the constraining structure includes four guides, each in
the form of a corner.
Each corner guide includes a pair of mutually angled tracks. Each
track is shaped substantially as a circular segment -- but the two tracks of each
corner guide have mutually offset centers. By this latter condition I mean that
the centers are offset along the corner line itself, where the two circular segments
It will be understood that the geometric circles that characterize
the circular segments are not in a common plane, as the tracks are mutually angled;
however, the circles nonetheless do have centers, and the center of each circle
can be projected onto the intersecting-segment corner line at its point of closest
approach -- i. e., the point where that line crosses a perpendicular radius
of the corresponding circle. By the statement that the centers are offset along
the corner line I thus mean, in turn, that these projection points are mutually
offset along that line.
The four corner guides are disposed in a generally rectangular or
square array. This statement is to be understood, for present purposes, as encompassing
an array in the shape of a parallelogram -- for there is no requirement that the
two interlocking bodies operate at right angles to each other, although as a practical
matter the simplest structures with the greatest operating ranges and greatest
general-purpose utility are likely to result from rotation of the two bodies at
right angles. The circular-segment tracks extend outward from the array.
In this embodiment of my invention, the pair of circular followers
of each body engages four of the circular-segment tracks, respectively, for rotation
of that body relative to those four tracks and accordingly relative to the corner-guide
array. That is, each circular follower engages two tracks.
The corner guides form a substantially hollow enclosure for passage
of the flexible flux-transmission means. As a result of the configuration described
above, both bodies rotate about the hollow enclosure.
Yet another form of my invention includes traction means that are
defined along at least one of the bodies. This form of the invention also includes
a discrete force-applying device for engaging the traction means to drive the
"at least one" body relative to the body-constraining structure. The discrete force-applying
device is mounted to the body-constraining structure, but is discrete in
the sense that neither the body nor the body-constraining structure is itself a
functioning component of the force-applying device.
In this regard my force-applying device differs from Rosheim's drive
unit, in which the force-applying devices are indistinguishable from the ring-and-guide
combinations. In Rosheim, as will be recalled, each ring carries a paddle or hydraulic
piston and thus serves as a circular piston ring, while each guide also serves
as a hydraulic chamber.
Still another form of my invention includes traction means that are
defined along the body-constraining structure, and a discrete motor, mounted to
at least one of the bodies, for engaging the traction means to drive the "at least
one" body relative to the constraining structure. Here too, the motor is
mounted to the constraining structure, but discrete in the sense stated
The last two forms or embodiments of my invention just described
can be generalized for description as a single form, in the following way -- emphasizing
that these two forms are equivalents. This form of the invention includes a pair
of body-and-constraint sets. Each of these sets includes a body member and a constraint-structure
Now using these definitions, traction means are defined along
one member of at least one set. Mounted to the other member of that
"at least one set" is a discrete motor for engaging the traction means -- to drive
the two members of the "at least one set" relative to each other.
As will be appreciated, this definition can be recouched to expressly
include mounting of discrete motors to drive each of the two body-and-constraint
sets. In either case, the body and constraining-structure members also answer
to other limitations expressed above for the rotating bodies and constraining
In particular, each body member defines a hole, and least part of
the body member is small enough to fit through the hole that is defined in the
body member of the other set; each constraint-structure member constrains the
body member of the same set for systematic movement; the body members of the two
sets are interlocking; and the constraint-structure members of the two sets are
interconnected so that in conjunction they constrain the two body members for systematic
All of the foregoing operational Principles and advantages of the
present invention will be more fully appreciated upon consideration of the following
detailed description, with reference to the appended drawings, of which:
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view showing an inner guide for use in one
preferred embodiment of my invention. In this particular embodiment the inner guide
is a unitary solid form.
Fig. 2 is a like view showing two of the Fig. 1 guides interfitted
to form a complete inner-guide structure, or body-constraining structure.
Fig. 3 is a like view showing the Fig. 2 guides not yet interfitted,
but with an outer ring or body mounted for rotation to each guide.
Fig. 4 is a like view showing the guides -- now carrying the outer
rings -- interfitted as before; and with stem sections oriented for insertion into
gaps in the rings, to complete the rings and thereby the assembly.
Fig. 5 is a like view showing an inner guide for use in a different
preferred embodiment. This inner guide is in essence a shell or skeleton, in which
only certain functional surfaces of the Fig. 1 guide are retained while most of
the mass or bulk is omitted. In this embodiment, the retained functional portions
include two opposing thin discs, and three thin planar connecting walls mutually
stabilizing the discs.
Fig. 6 is a like view of two inner guides for use in yet a third
preferred embodiment, from which have been omitted the three planar walls also.
In this embodiment only the discs remain, and these can be mutually positioned
by other elements -- namely, for example, either interconnecting pillars, or mating
surfaces of the outer rings which ride on the guides.
Fig. 7 is a like view showing the two Fig. 6 guides interfitted.
Fig. 8 is a like view showing the two outer rings for use in the
same (third) embodiment with the guide discs of Figs. 6 and 7. These outer rings
provide guide surfaces for orienting the discs.
Fig. 9 is a like view showing two stem elements for insertion into
the Fig. 8 rings, to both complete the rings and provide article-attachment means
in the same (third) embodiment.
Fig. 10 is a like view showing a ring gear in conjunction with one
of the Fig. 8 rings.
Fig. 11 is a like view showing an embodiment that is a variant of
the Fig. 10 geometry.
Fig. 12 is a like view, partially broken away, showing motor means
and flux-transmission means, in conjunction with the above-enumerated components
of the Fig. 10 embodiment.
Fig. 12a is a cross-sectional elevation of the Fig. 11 variant embodiment,
in a context similar to that of the Fig. 12 apparatus.
Fig. 13 is a perspective view similar to that of Fig. 12, but not
cut away, showing the entire Fig. 12a variant embodiment ready for operation --
with ring gears mounted to the connection stems on the outer rings, and drive
motors mounted to the inner slotted-disc guide assembly. This view is implicitly
taken in the frame of reference of the inner guide assembly: i. e., both
rings (and stems) are shown as rotating about that inner assembly.
Fig. 14 is a like view showing the Fig. 12a embodiment in a more
typical or practical context: one ring is fixed to a base that is taken as stationary;
the inner assembly rotating within that fixed ring, and the second ring rotating
about the inner assembly. This view is in effect taken from the frame of reference
of the stationary base, or the world -- the so-called "inertial frame" of reference.
(In terms of relative motion of the inner structure with respect to the
rings, there is no difference between the two points of view.)
Fig. 15 is a like view showing an inner guide for use in a fourth
embodiment of my invention. This is a corner guide, described and discussed previously.
Fig. 16 is a like view of four corner guides, two of which are identical
to that of Fig. 14, arrayed in correct relative position.
Fig. 17 is a cross-sectional elevation of the Fig. 14 array, taken
"end on", assembled with two outer rings.
Fig. 18 is a perspective view showing the Fig. 14 corner-guide array
in conjunction with two outer rings for assembly with the corner guides, in constructing
the fourth embodiment of my invention.
Fig. 19 is a cross-section of the Fig. 18 parts assembled.
Fig. 20 is a perspective view, partially broken away, of an assembly
first disclosed in my above-mentioned earlier patent applications, and conceptually
related to the fourth embodiment of my invention.
Fig. 21 is a perspective view of the corner-guide array of Figs.
16 through 19, here shown with details of one form of rotating engagement to the
outer rings or bodies, and in conjunction with two ring gears for assembly to
the corner guides.
Fig. 22 is a like view of an outer ring for use with the Fig. 21
corner-guide-and-ring-gear array, and particularly showing part of flux-transmission
means incorporated into the ring.
Fig. 23 is a like view, partially broken away, of the entire assembly
that makes up the fourth embodiment of my invention -- with ring gears mounted
to the inner corner-guide assembly, and drive motors mounted to the stems on the
outer rings. It is thus in a sense an "opposite" construction from that of Figs.
12 through 14, in which the ring gears are on the outer rings and the motors on
the inner assembly.
Fig. 24 is a like view, but fragmentary -- and focusing upon the
flexible flux-transmission means as they cross through the hollow central enclosure,
passing between the two outer rings.
Fig. 25 is a like view, ending in a cutoff or sectional view, showing
one configuration for assembling the flux-transmission means to the outer ring.
Fig. 26 is an external perspective view of the fourth embodiment,
again emphasizing motion of its components from the frame of reference of the inner
Fig. 27 is a like view of a variant of the third
of Fig. 12, but incorporating four different discrete motors to drive each ring
-- for a total of eight motors, all mounted to the inner guides or body-constraining
Fig. 28 is a like view, but returning to the inertial frame as in
Fig. 13, of a fifth embodiment of my invention. This is a system employing three
of the third-embodiment devices -- all assembled in cascade, to provide a mechanical
arm complete with "shoulder", "elbow" and "wrist" joints.
Fig. 29 is a cross-sectional and somewhat schematic view of a sixth
embodiment of my invention, which may be conceptualized as one possible cross-combination
of the features of Figs. 23 and 12. Thus, Fig. 29 shows stem-
mounted motors (as in Figs. 23 and 26) with slotted-disc
in Figs. 6, 7, 12 and 12a).
Fig. 29a is a perspective detail view of the drive geometry of Fig.
Another cross-combination is shown in the seventh embodiment of Fig.
30, a cross-sectional view similar to Fig. 29. Fig. 30 shows inner-structure-mounted
motors (as in Fig. 12) with corner guides (as in Fig. 23). From a comparison of
Figs. 12, 23, 29 and 30 it will be understood that the features illustrated are
to some degree independent.
Fig. 31 is a perspective view of an embodiment that is closely related
to that of Fig. 18, but employing variant constructions for the outer bodies and
Fig. 32 is a cross-sectional elevation of a portion of the outer
body of Fig. 31.
Fig. 33 is a like view of a portion of the constraining structure
of Fig. 31.
Fig. 34 is a like view showing interengagement of the outer-body
and constraining-structure portions of Figs. 32 and 33 respectively.
Fig. 35 is a perspective and fanciful view showing yet another type
of guide structure, to exemplify the general proposition that the functional portions
of the inner guides are the arcuate guiding-edge or guiding-surface segments themselves,
and that the interconnecting structure or structures that mutually dispose the
guiding edges or surfaces for proper engagement with the outer rings can be arbitrary.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As seen in Fig. 1, a fundamental element of one preferred form of
my invention is a slotted solid right circular cylinder 10. The cylinder has a
first planar end wall 11-12-13, and a second planar end wall 14.
The two end walls are separated by a generally cylindrical wall 15,
which also intersects along corners 16 two planar top and bottom walls 17 and 19
of a slot or cutout 17-18-19. Interconnecting these two planar walls 17 and 19
of the slot, and within the slot, is a third planar back wall 18.
As will be clear, the three planar walls 17, 18 and 19 of the slot
also separate the two planar end walls 11-12-13 and 14 of the cylinder. The top
and bottom walls 17 and 19 are sufficiently long as to extend past the central
axis of the cylinder 10.
The planar face of the first end wall 11-12-13 can be helpfully conceptualized
as consisting of three portions. The reason for identifying these different areas
with specificity will shortly become clear.
The "three portions" of the end wall are (1) a lower circular-segmental
area 11, extending all the way across the cylinder below the bottom wall 19 of
the slot; (2) an identical upper circular-segmental area 13, extending all the
way across the cylinder above the top wall 17 of the slot; and (3) an intermediate
area 12 between the upper and lower circular-segmental areas 11 and 13 -- which
is to say, between the planar back wall 18 of the slot and the cylindrical surface
15&min; that is aligned with that planar back wall 18. The cylindrical surface
15, 15&min; forms a guide and support surface for operation of a mating outer
body, which as will be seen can be a ring.
Two slotted cylinders 10a, 10b -- each identical to the slotted cylinder
10 of Fig. 1 -- are shown interfitted in Fig. 2. All of the same reference numerals
11 through 19 used in Fig. 1 are used for the like elements in Fig. 2, with the
addition of a suffix "a" or "b" to distinguish the corresponding
elements of the two cylinders respectively.
When two Fig. 1 slotted cylinders are interfitted in this way, the
surface 18 at the back of the slot 17-18-19 in one Fig. 1 slotted cylinder 10 will
abut or nearly abut the surface 18 at the back of the other Fig. 1 cylinder. Those
abutting surfaces cannot be seen in Fig. 2.
From Fig. 2 it can be seen, however, that the two slotted cylinders
engage each other closely. It may be understood accordingly that the heights of
the two cylindrical surfaces 15a and 15b very nearly equal the widths of the two
corresponding slots 17-18-19b and 17-18-19a respectively.
The structure of Fig. 2 defines, among other features, four inward-extending
corners between the planar circular-segmental portions 13a, 13b, etc. One of these
inward-extending corners 13ab is visible in Fig. 2. The importance of the compound
surface 13a-13ab-13b, and the four other compound surfaces formed by the two interfitted
cylinders 10a, 10b will shortly become clear.
In Fig. 3 the same two slotted cylinders 10a, 10b are shown not yet
interfitted, but carrying slotted outer rings 20a, 20b respectively. The outer
rings may be mutually identical as shown, each with a respective pair of side
walls 21a (on ring 20a) and 21b (on ring 20b), an outer generally cylindrical surface
22a, 22b; an inner generally cylindrical surface 23a, 23b, and a pair of end walls
24a (for ring 20a) and 24b (for ring 20b) where the ring is interrupted or notched.
The widths of the notches between the two surfaces 24a and between
the two surfaces 24b match the widths of the two corresponding slots 17-18-19a
and 17-18-19b (Fig. 2) in the respective slotted cylinders 10a, 10b. Each ring
20a, 20b is coaxial with the corresponding slotted cylinder 10a, 10b and is free
to rotate about the common axis either clockwise as suggested (for ring 20a) by
the arrow 35a, or counterclockwise as shown by the arrow 35a&min; -- that is,
with the inner cylindrical surface 23a, 23b sliding upon the outer cylindrical
surface 15a, 15b of the corresponding cylinder 10, 10b respectively.
To retain each ring 20a, 20b axially in place relative to its corresponding
cylinder 10a, 10b, an inward-projecting tongue 31a, 31b may be formed or secured
along the inner circumference 23a, 23b of each ring, and a mating groove defined
in the outer cylindrical surface 15a, 15b of the corresponding cylinder -- or
conversely. (To permit assembly of these structures without interference, depending
upon the degree of flexibility of the materials used for the cylinders and rings,
or upon the number of pieces from which each cylinder or ring is constructed, it
may be necessary to form the tongues 31a, 31b as separate strips, and to glue
or otherwise affix the tongues to the rings 20a, 20b as convenient.)
As will be apparent to those skilled in the art of mechanical assemblies,
any of an enormous range of equivalents may be substituted for the tongue-and-groove
structure illustrated. When the two subassemblies are complete as shown in Fig.
3, they are interfitted by moving them toward each other in the directions indicated
by the arrows 34.
The result is then as indicated in Fig. 4. The rings 20a, 20b are
then completed by addition of short annular-segmental inserts 32a, 32b respectively,
which are positioned and glued or otherwise secured into the gaps defined between
the surfaces 24a, 24b.
These annular-segmental inserts 32a, 32b optionally have inner cylindrical
surfaces that substantially match and align with the inner cylindrical surfaces
of the respective rings 20a, 20b. This alignment allows the inserts 32a, 32b to
slide along the outer cylindrical surfaces 15a, 15b respectively, as continuations
of the inner surfaces of the rotating rings.
After assembly, the inserts 32a, 32b preferably (in most cases) extend
outward radially from their respective rings 20a, 20b. Such protrusion provides
connective stems for attachment at one side of the joint to an operating base
or the like, and at the other side to a working head of some sort.
The construction of Fig. 4 also exemplifies the fact that the inner
structure 13a-13ab-13b, etc. need not fill all the space within each ring. Thus
after an annular-segmental insert 32b is fitted into the gap 24b in one ring 20b
-- in such a way that the inner cylindrical surface of the insert 32b is aligned
with the matching inner cylindrical surface 23a of the ring 20a, a portion of
the inner planar wall 19b (that defines the slot 17b-18b-19b in the corresponding
cylinder 10b) yet remains exposed. If desired, the gap can be used to accommodate
great radial irregularity in the "ring" or body surface geometry, which can accordingly
The solid construction of Figs. 1 through 4 is capable of serving
as a mechanical joint in accordance with my invention as most broadly defined earlier
in this document. This construction can be fitted with slip rings or sliding tubing
fittings for transmission of electrical, optical or fluid fluxes into or across
the joint -- generally as described in my previously mentioned patent applications.
For particularly convenient and economical flux transmission into
or across the joint, however, benefits accrue from eliminating most of the solid
interiors of the slotted cylinders 10a, 10b. Flexible transmission means can then
pass through the interior of the compound inner structure 10a, 10b without impeding
rotation of the rings upon the cylinders.
One way in which this can be done is to form each of the slotted
cylinders as only a shell or exoskeleton -- omitting almost all of the cylindrical
surfaces -- as shown in Fig. 5. Thin slotted discs 111-112-113, 111&min;-112&min;
are retained; they are interconnected only by thin planar walls 117, 118, 119 defining
the original (Fig. 1) "slot" as shown.
In Fig. 5 and all of the remaining drawings (except Fig. 20) in this
document, the same reference numerals are employed as in Figs. 1 through 4 for
like elements, but with an additional prefix distinguishing the various embodiments
from one another. Thus in Fig. 5 the prefix is a single numeral "1", so that the
Fig. 1 surface "13" becomes in Fig. 5 a corresponding surface "113"; and in Figs.
18 and 21 the prefix is "3" so that the corresponding surface becomes (with an
additional suffix explained earlier) a surface "313a"; etc.
In Fig. 5 the cylindrical wall of Fig. 1 is almost entirely eliminated,
leaving only the thin generally cylindrical surfaces or edges 115, 115&min; of
the thin discs 112, 112&min; respectively. These edges 115, 115&min; can serve
as tracks or guides for an outer ring (not shown).
In this drawing and many of those that follow, an apostrophe or "prime"
sign is appended to. the reference numerals of one in each pair of thin discs that
are parallel, aligned and spaced apart -- to distinguish them from each other.
The same notation is also used to distinguish features or parts of these disc pairs,
and other components such as motors that are associated with the individual discs.
(The prime sign is also used in the drawings of this document in various other
ways and for different purposes, as will be clear from the context.)
The outer ring can be annularly grooved or otherwise fashioned to
ride upon and engage the tracks or guide edges 115, 115&min;. With two such shell-like
cylinders and a pair of mating rings, interfitted as in Fig. 4, the resulting
structure can function exactly as that of Fig. 4 -- except for the saving in material,
and the added capability for passing flexible connections through the hollow space.
In regard to the passage of such connections, it will be understood
that such connections must somehow traverse the back-wall panel 118 -- and, in
fact, two of such panels, since the slot back-wall panel 118 of each shell cylinder
will abut the corresponding panel of the other, just as the two slot back-wall
surfaces 18 of two solid Fig. 1 cylinders abut when the two solid cylinders are
interfitted as in Fig. 2.
These necessary through-connections can be fastened securely into
the abutting slot back-wall panel 118, as for example by a conventional strain-relief
device. Alternatively, they can be passed loosely through oversize apertures in
An even more satisfactory construction of the inner guides, however,
is shown in Figs. 6 and 7. Now it can be appreciated that four identical thin discs
210a, 210a&min;, 210b, 210b&min; suffice to provide four cylindrical tracks 215a,
215a&min;, etc. for constraining the motion of two outer rings.
The discs 210a, 210a&min; are spaced apart, and the discs 210b, 210b&min;
are also spaced apart, in pairs to form a generally rectangular array as Fig. 7
shows, just as if the walls 117, 118, 119 were still present. This spacing can
be provided in any of a large variety of ways.
For example, four discs can be arranged in the Fig. 7 array by gluing
or otherwise securing them together along the inside corner lines 211ab, or in
any event at enough points where the discs make contact to stabilize the structure.
Alternatively, the discs can be held apart, and in position, by interconnecting
pillars or the like. Still otherwise, the entire Fig. 7 array can be molded in,
e. g., one piece.
I have found, however, that for many practical structures of a lightweight,
light-duty character it suffices to space the discs apart by means of the follower
surfaces, defined in the mating outer rings, that ride upon the disc edges. Such
a function can be performed, for example, by the angled follower grooves 226a,
226a&min;, 226b, 226b&min; shown in Fig. 8.
The rings in Fig. 8 are otherwise very similar to those of Figs.
3 and 4, having respective gaps 224a, 224b that are closed by mating annular-segmental
inserts 232a, 232b (Fig. 9) respectively. Integral with these inserts are attachment
stems 233a, 233b -- provided for the purposes indicated earlier, and also elaborated
in my previously mentioned patent applications. The two insert-and-stem assemblies
230a, 230b can be mutually identical if the rings 220a, 220b are identical.
In applications of my invention for robotics and other self-actuating
devices, it is desirable to apply force between force-applying means such as a
motor/driving-gear combination and some force-receiving or traction means such
as a receiving gear. A receiving gear may for instance take the form of a ring
gear, fixed either to the interlocking rings (or other bodies) of my invention
or to the inner guide structure.
Fig. 10 illustrates such a ring gear 250, that can be fixed at the
side of one of the rings 220 already introduced above. The ring gear 250 can be
an arcuate annulus 251 with a gap 253, gear teeth 252 formed along an inner circular
periphery, and holes 254 for mounting screws 254&min;.
The gear 250 is assembled to the ring 220 by moving the gear against
the ring as suggested by the arrow 235, and then inserting and tightening the mounting
screws 254&min;. The same result can be obtained -- where suitable in terms of
material strength, production volume, and so forth -- by molding the ring 220 and
gear teeth 252 integrally, with the teeth 252 formed in the side 221 of the ring
For optimum rotational range of the complete assembly, the gap 253
in the ring gear 250 is not aligned with the gap 224 in the ring 220, although
such alignment might seem intuitively to be appropriate. Rather, the gap in the
ring gear should be oriented so that it is diametrically opposite the position
along the ring where the ring gear engages the motor-powered driving gear, when
the joint is fully extended -- i. e., with the two stems substantially aligned.
This condition will be further discussed shortly.
The ring-gear teeth need not be along the outside edge of the ring
220, but can instead be further inboard, between the two dovetail grooves that
will ride on the slotted-disc tracks 215a, 215a&min;, 215b, 215b&min; of Figs.
6 and 7. In this alternative configuration, shown by Fig. 11, all the gear teeth
will be within the structure, concealed and protected between the slotted discs;
this form too may either be assembled from two pieces or molded as a unitary component.
For many applications the Fig. 11 variant will be preferred for reasons
of safety and reduced noise. In environments involving corrosive atmospheres, flying
metal chips, and the like, this variant embodiment may also require less maintenance.
For other applications, however, the Fig. 10 configuration may be preferred because
it permits readier wear inspection of the gear teeth, or possibly just because
it is more interesting or engaging to watch in operation.
In Fig. 12, the Fig. 10 ring-and-ring-gear configuration is shown
assembled with the slotted-disc guide structure 210a-210a&min;-210b-210b&min; of
Figs. 6 and 7 -- all incorporated into a complete self-moving joint, together
with motors 240a, 240b and flux-transmission means 261a-262a-264-262b-261b. Some
components are drawn broken away, at 299, for a view of the interior. In the particular
arrangement illustrated, the slotted disc portions 211b&min;, 211a and 211a&min;
are notched as at 257b, 257a (and at other points not visible in the drawing) for
passage of the respective ring gears 251a, 252b.
Each motor 240a, 240b may be powered by, e. g., air, electricity
or hydraulic fluid, and controlled by pneumatic, electrical, hydraulic or optical
signals. Each motor has a drive shaft 242a-243a, 242b-243b, which near its inboard
end carries a drive pinion 244a, 244b and is journalled into a respective portion
213a, 211b&min; of one of the slotted discs.
Each motor is further fixed to the central compound guide structure
by a bracket (not shown in Fig. 12). Further, each motor is secured in such a position
that its drive pinion 244a, 244b engages the teeth 252a, 252b of the corresponding
As previously mentioned, the gap 253a, 253b in each ring gear is
angularly offset along the ring from the respective stem 233a, 233b. This condition
is necessary to avoid limiting the driven rotation of the stem by running either
drive pinion 244a, 244b off the end of its own ring gear 251a, 25ab. (An alternative
is to assemble the ring gear of two segments, or otherwise form the ring gear,
with no gap.)
More specifically, when the stems 233a and 233b are aligned linearly
with each other, each motor pinion 244a, 244b should be at the midpoint
of its relative travel along its respective ring gear 251a, 251b -- so that the
stem 233a, 233b on each ring can rotate fully against either side 221b, 221a of
the other ring (or against the side 251b, 251a of the other ring gear) before
the drive pinion 244a, 244b runs off either end of its own ring gear 251a, 251b.
As can be visualized from Fig. 12, when the upper stem 233b is rotated
downward and backward (i. e., rightward and into the plane of the drawing)
the gap 253b in the associated ring gear 251b will move from the bottom of the
drawing upward and forward (i. e., leftward and out of the plane of the
drawing). During all of this motion, the motor-shaft journal 247b remains in the
illustrated position: what is under discussion here is rotation of the ring 221b
which appears vertical in the drawing, about the central compound structure, while
the latter structure remains stationary.
As this motion continues, the axis of the upper stem 233b will soon
reach a point at which it is essentially in the plane of the ring 251a that appears
horizontal in Fig. 12. At that point, that upper stem 233b is in
the middle of its travel -- halfway between impinging upon one side or the other
of the horizontal ring 251a. At that same point the associated ring gear 251b must
be oriented so that it too is at the center of its travel relative to its drive
pinion 244b -- halfway between the points at which it would run off into the gap
253b in one direction or the other.
This condition is satisfied if the gap 253b is diametrically opposite
the motor-shaft journal 247b in the associated disc 221b. For a motor-shaft journal
247a, 247b formed where shown in Fig. 12, a roughly correct position for the ring-gear
gap 253 relative to the ring gap 224 appears in Fig. 10.
Given the foregoing insights and information, a person skilled in
the art of mechanical design will be able to find the correct position very readily
by calculation or by actually aligning the apparatus as described above and holding
it in that position while selecting the mounting orientation for the ring gear.
Of course the analogous alignment must be made for the other ring gear on the
Fig. 12 also shows how to route flux-transmission means of a flexible
construction -- that is, typically flexible wires, optic fibers, tubing or the
like -- through the central cavity 269, without reducing the angular operating
range of either stem. By reference to Figs. 12 and 7 in conjunction, one may visualize
the fact that transmission means protruding inward from an inner surface of the
"horizontal" ring 221a (Fig. 12) have access to the space between the two "horizontal"
discs 210a, 210a&min; (Fig. 7) without interruption, while the ring 221a rotates
-- except when the ring reaches a position at which the transmission means
are at the gap or slot 217a (Fig. 7).
In operation, that gap is always occupied -- by the "vertical"
ring 221b (Fig. 12). Therefore that vertical ring 221b can obstruct inward-protruding
transmission means, when they reach the gap 217a.
To maximize the angular operating range of the "horizontal" ring,
therefore, the transmission means should protrude inward from the inner surface
of the ring 221a at a point along that inner surface which never
reaches the gap 217a. This can be accomplished, for there is such a point
-- remembering that angular rotation of the stem 233a (Fig. 12) is limited by
impingement on either side of the other ring 221b.
The stem 233a, however, protrudes outward from its ring 221a;
whereas the transmission means are to protrude inward. Accordingly, although
the transmission means impinge upon the vertical ring 221b at the point where
that ring passes just inside the horizontal ring 221a, the stem impinges
upon the vertical ring 221b at the point where that ring passes just
outside the horizontal ring 221a.
A solution is to introduce the transmission means into the interior
space at a point along the inside of the ring 221a that is diametrally opposite
the stem 233a on that same ring. This condition establishes that only when the
outward-projecting stem 233a is rotated almost halfway around in either direction
to impinge upon the vertical ring, where it passes just outside the horizontal
ring, will the transmission means approach impingement upon the vertical ring
where it passes just inside.
To prevent potential damage through actual impingement of the transmission
means, the area through which the transmission means protrude inward need only
be made slightly narrower in angular extent than the stem. Fig. 12 illustrates
part of the mechanics for laying the transmission means along a route where they
cannot impede the angular operating range of either stem and where they cannot
Specifically, the wires, optical fibers, tubing or the like are preferably
introduced into the joint through or along one stem 233a, and can then be routed
along circumferential paths 262a as for example within grooves 263a in an outer
surface of the associated ring 221a. Alternatively they may be routed along an
inner surface, or embedded within the ring; or some of the transmission means
may follow one path while other transmission means follow one or more different
paths. In any of these cases, the transmission means follow the ring to a point
(not visible in Fig. 12) that is diametrically opposite the entry stem 233a.
At that point the transmission means pass from the ring into the
inner structure, and more specifically into the space between the two "horizontal"
slotted discs 211a-213a, 211a&min; -- that is, between the two "horizontal" discs
210a and 210a&min; of Figs. 6 and 7. From that entry region, the transmission means
lead to the similar space 269 (Fig. 12) that is between the two "vertical" discs
210b and 210b&min; of Figs. 6 and 7.
From this latter cavity 269, the flexible transmission means pass
through (or into, or attach to) the "vertical" ring 221b. In the particular system
illustrated in Fig. 12, they again follow an exterior circumferential path 262b,
laid along grooves 263b in the exterior surface of the ring, to the stem 233b of
the "vertical" ring 221b. The transmission means 261b then pass through or along
that stem 233b and out of the joint.
Whereas Fig. 12 illustrates an assembly that incorporates exterior
ring gears like the gear 250 in Fig. 10, Fig. 12a illustrates the incorporation
of an interior ring gear 552 like the gear 552, 552&min; in Fig. 11. Here the
motor shaft 543a passes entirely through, rather than being journalled in, the
disc 513a -- so that the drive pinion can be engaged with the ring gear 552a
inside the space between the two horizontal discs 513a, 513a&min;.
As will be noted, the system of Fig. 12a is otherwise very similar
to Fig. 12, following all of the same principles just detailed for angular alignment
of the ring-gear gap, and for location of the inward-protrusion point of the transmission
means from each ring 521a, 521b&min;. Particularly included in Fig. 12a are the
central cavity 569 that makes possible the use of flexible transmission means;
and a motor bracket 548a which, as shown, can secure the motor casing 541a to a
different disc 511b than the disc 513a through which the motor shaft 543a
The external appearance of the Fig. 12a system appears in perspective
in Fig. 13, which as will be understood is very similar in appearance to the system
of Fig. 12 -- the major difference being that the drive pinions and ring gears
are concealed out of view inside the Fig. 13 structure. Fig. 13 also illustrates
that the shapes of the stems 233a, 233b need not be mutually identical, and in
fact can be virtually arbitrary provided that they are not so wide -- in their
respective directions 235a-235a&min;, 235b-235b&min; of rotation -- as to unduly
limit their angular operating ranges.
In Fig. 13 as in earlier illustrations, the motors are shown as mounted
to the inner guide structure. This is not a necessary condition, and as will be
shown later the motors can be mounted to the rings -- or even in the stems.
Fig. 14 can be understood to illustrate the same joint, but more
explicitly in the inertial frame. That is to say, one stem 233a is mounted to a
generally stationary base 271; and accordingly that stem 233a and its associated
ring 221a-222a are themselves generally stationary -- although, if desired, an
additional degree of freedom can be obtained by rotation of the stem 233a, about
its own axis, relative to the base 271 or relative to the ring 221a-222a.
In this case the relative motion of that stem 233a and ring 221a-222a
with respect to the inner guide structure 211a-211b&min; etc. accordingly takes
the form of rotation of the guide structure -- within the stationary
ring. The relative motion of the second ring 221b-222b then is the more intuitively
direct rotation of that second ring about the guide structure.
A representative article is shown as mounted to the second stem 233b,
for rotation with the second ring 221b, 222b. This is a type of item which may
be usefully positioned automatically, or by manual operation of a gear-to-gear
mechanism for fine adjustment -- or even by completely manual operation.
Accordingly although, as noted above, the elements marked 240a and
240b in Fig. 14 may represent the motors discussed earlier in connection with Figs.
12, 12a and 13, these elements 240a, 240b are to be taken as alternatively
certain other mechanical components. First, they can be manually rotated knobs,
connected to drive pinions 244a, 244b of Fig. 12 -- to advance the mechanism along
the two ring gears as in the automatic operation described previously.
Second, the elements 240a, 240b can be taken instead simply as handles
for direct manipulation of the rings 221a, 221b. In this variant of the Fig. 14
embodiment, there are no internal gears at all -- neither pinions nor ring gears
-- and the relative rotation of the rings 221a, 221b with respect to the inner
guides 210a, 210a&min;, 210b, 210b&min; is effected simply as a sliding motion.
If desired the handles 240a, 240b can be rotatably fixed to screw
shafts that are threaded into the inner guide structure. They can thereby also
serve as screw clamps, to hold the respective rings 221a, 221b in place on the
All of these Fig. 14 variants just discussed are fully compatible
with flux transmission through the joint, as already described.
Appearing in each of Figs. 7, 12, 13 and 14 is a conspicuous substructure,
the internal-corner shape formed by the two circular-segmental disc portions 211a
and 211b&min; in the upper-right quadrant of the illustration. These two segments
211a, 211b&min; intersect at an internal-corner line 211ab -- as pointed out above
in discussion of Fig. 2, with respect to the analogous segmental surfaces 13a,
13b and the corner line 13ab.
This observation has led me to realize that these corner shapes themselves,
rather than the individual discs, can be treated as the fundamental units of the
inner guide structure. Each of the corner shapes can be isolated as a one-piece
element 310ab, shown in Fig. 15.
Here the two adjacent segments are 313a (with circular-segmental
guide edge 315a) and 311b (with a like track 315b). These intersect along the internal-corner
Also appearing in Fig. 15 are two purely geometric reference lines:
radii ra and rb of the two circles of which
the guide edges 315a, 315b are respective segments. These radii are both constructed
perpendicular to the corner line 311b/313a; therefore their respective intersections
with that corner line represent the closest points along that line to the
centers of the two circles respectively.
Fig. 15 thus demonstrates that the centers of the two circles are
mutually offset along the intersection line 311b/313a. To couch this in more mechanical
terms, since only the segments rather than the full circles are present, the centers
of the two segments are mutually offset.
The article shown in Fig. 15 is somewhat abstract in that the two
segments are joined only along a geometric line, which of course as no structural
strength. The two segments accordingly can be extended, along their common corner
line, to form a solid connection region as illustrated most clearly in Figs. 17,
18, 19, 21 and 23.
Fig. 16 shows a full array of four corners 310ab, 310ab&min;, 310a&min;b
and 310a&min;b&min; used in an operating joint according to my invention. The segments
that make up these four corners are identified according to the reference-numeral
notation defined earlier in this document.
By careful consideration of Fig. 16 one can recognize that the diagonally
opposite corners 310ab and 310a&min;b&min; are identical to each other, and accordingly
this pair of corners is interchangeable. Similarly, the remaining two diagonally
opposite corners 310a&min;b and 310ab&min; are identical to each other -- constituting
another pair of interchangeable corners.
The structure does, however, have an asymmetry or handedness. The
two pairs are different from one another, and not interchangeable.
This is very important as a practical matter as it means that two different types
of corners, not just one type, must be manufactured.
The geometry of the Fig. 16 corner array can be maintained by the
rings that rotate upon it, while conversely the rings are kept in position by the
corner array. In other words, the structural elements can be made mutually interdependent,
as shown in Fig. 17.
For this purpose the edges 315a, 315a&min;, 315b, 315b&min; of the
corner segments are formed with dovetail cross-sections as illustrated, to engage
complementary shapes (like those shown in Fig. 8 at 226a, 226a&min;, 226b, 226b&min;)
along the inner edges of the rings 320a, 320b. As Fig. 17 makes clear, the interior
cavity 369 of the corner-guide structure is even more open or unobstructed than
that of the crossed-disc structure discussed earlier.
In the system of Fig. 17, it is particularly easy to lock the rings
320a, 320b in place on the guide structure. This can be accomplished simply by
passing a bolt or the like (not shown) diagonally through holes (not shown) in
any two opposite corners -- e. g., between the corner 311a&min;/313b&min;
and the corner 311b/313a -- and tightening the bolt to jam the entire assembly.
Figs. 18 and 19 show a similar structure, using square-cross-section
guide edges, that is assembled from split rings 321a, 321a&min;, 322b, 322b&min;
that have integrally formed split stems 333a, 333a&min;, 333b, 333b&min;. Only
one ring actually need be split, to allow interlocking; but splitting both reduces
tooling cost. Flux-transmission means can be threaded through holes 337a, 337b-337b&min;
in the half-stems 333a, 333b.
This corner-guide embodiment can be adapted for heavier-duty applications,
and motorized as well. If desired, the motors can be mounted in the stems; the
result is closely related to an embodiment first presented in my above-mentioned
earlier patent applications and repeated here at Fig. 20.
The toroids 721 and 731 of Fig. 20 are provided, around the peripheries
of their central apertures, with internal grooves. Internal rings 781 and 791 respectively
are fitted within these grooves.
The internal rings 781 and 791 are mutually interlocked, and are
mutually fixed at a common area 788 along the inner peripheries of both rings.
The rings 781 and 791 are provided with force-transmitting surfaces 782 and 792
The force-transmitting surfaces 782 and 792 are thus defined along
very generally circular paths within the respective toroids. Disposed in respective
engagement with these surfaces 782 and 792 are mating force-transmitting elements
713 and 743.
These elements 713 and 743 are mounted for rotation in the respective
toroidal bodies 721 and 731. Although the force-transmitting elements 713 and 743
are free to rotate about their own axes, those axes are fixed in position along
the endless toroidal bodies 721, 731.
The force-transmitting elements 713 and 743 are so shaped, and are
engaged with the force-transmitting surfaces 782 and 792 in such a way, that when
the elements 713 and 743 rotate they force the force-transmitting surfaces 782
and 792 to move relative to the rotational-axis locations. In other words, the
force-transmitting surfaces 782 and 792 are forced to move within the grooves
in the toroidal bodies 721 and 731.
Such motion of the surfaces 782 and 792 of course requires motion
of the inner rings 781 and 791 along which the force-transmitting surfaces are
defined. Consequently the inner rings 781 and 791 rotate relative to the toroids
721 and 731.
Connection elements 711 and 741 are provided on the toroids 721 and
731, at the fixed positions desired for the rotational axes of the force-transmitting
elements 713 and 743. Motor casings 756 and 757 are fixed to the connection points
711, 741, and the driveshafts 712 and 742 of the motors are journalled through
the bodies of the toroids 721 and 731.
The ends of these driveshafts remote from their motors are fixed
to the force-transmitting elements 713 and 743 in such a way that operation of
the motors rotates the force-transmitting elements, resulting as previously stated
in motion of the inner rings 781 and 791 relative to the toroidal bodies 721 and
For greatest strength and transmission of relatively large forces,
the force-transmitting surfaces 782 and 792 may be annular gear teeth defined in
the rings 781 and 791. The force-transmitting elements 713 and 743, naturally,
are then pinion gears adapted to drive the gear teeth 782 and 792.
Various sorts of gears may be employed, including the bevel ring
gears 782, 792 and matching conical pinions 713, 743 illustrated in Fig. 20. Straight
and even helical drive gears may be substituted for various purposes, with appropriate
reconfiguration of the two ring gears 781, 791.
The selection of particular gearing forms should be appropriate to
the different force levels, speeds, and other details of each application at hand.
Suitable selection and design criteria for such gearing will be clear to those
skilled in the art of mechanical design.
As will also be clear to such skilled artisans, it is not necessary
to use gears at all. Rather, for some applications, a traction surface may be substituted
for either or both of the gear sets 782 and 792; and mating drive wheels may be
substituted for either or both of the pinions 713 and 743.
Suitable materials for both the traction surface at 782 or 792 and
the drive wheels at 713 or 743 may include elastomers with various degrees of resiliency
and tack. Generally smoother operation and finer adjustment increments will be
available with such systems, though for relatively lower levels of transmitted
The motors 756 and 757 may be entirely concealed within the connection
points 711, 741 or even within the toroidal bodies 721, 731; or they may be in
plain view. The motors may share the connection points 711, 741 with articles
to be connected to the joint for mutual motion; or separate connection means
for such articles may be provided along the peripheries of the toroids.
Furthermore, the motors may be electrical, air, or liquid motors.
Their electrical, air or liquid drive power may be supplied through separate conductive
wiring or tubing; or preferably, as suggested earlier, through the joint itself.
Study of Fig. 20, in conjunction with other disclosures in my earlier
patent applications, will reveal that the inclusion of electrical, optical or fluid
circuits within the joint is entirely compatible with the provision of tractive
surfaces and elements per Fig. 20. Consequently power, fluids, or optical radiation,
or any combinations of these, to manipulate the joint itself may be supplied through
the joint as well as power, fluids or radiation, or combinations thereof, for other
Fig. 20 may also be taken as representing a joystick device in which
the joint is manipulated manually. In such a device the elements 756 and 757 are
not motors, but instead are electrical-signal or fluid-motion generators responsive
to the motion of the joint.
Not only conventional electrical generators or alternators, but also
modern electromechanical sensors (such as finely graduated radial-contact arrays)
or electromagnetic angular-motion sensors or counters may be employed for optimum
economy, and/or compatibility with modern digital-logic utilization circuits.
With all of this in mind, I shall now proceed to disclose a motorized
variant of my corner-guide, hollow-inner-structure system introduced in Figs. 15
through 19 above. The corner guides in this motorized variant appear in Fig. 21,
together with ring gears 350a, 350b. The gear teeth 352a, 352b are on the outer
peripheries of the gears 350a, 350b, rather than the inner peripheries as in Figs.
10 through 12.
One ring gear 350a has clearance holes 354a for attachment by screws
to the corresponding threaded holes 355a in the two forward and vertical (as pictured)
corner segments 313a and 311a. The gap 353a in the ring gear 350a in this embodiment
is positioned to coincide with the space between those two corner segments 313a,
This configuration will satisfy by default the earlier-mentioned
condition that the ring-gear gap be opposite to the motor-pinion-gear drive point
when the joint is fully extended -- because the motor is itself in the stem (as
in Fig. 20), and at full extension the stem is aligned with the space between the
corner segments 313a, 311a.
Fig. 21 also shows conical rollers 329a&min;, 329b&min; mounted to
the inward-facing surfaces of the corner guides, adjacent to the arcuate edges.
Three rollers are shown for each segment; this gives a reasonable practical tradeoff
between kinematics and force bearing, and will be suitable for many light-duty
or medium-duty applications. For heavier systems, more rollers may be used.
Fig. 22 shows a suitable ring for use with the corner guides and
ring gears of Fig. 21. As will be recognized, this ring includes flux-transmission
means 328b-328b&min; and is substantially identical with those used in the system
of Fig. 12. Here, however, the ducktail grooves 326b, 326b&min; will ride on the
conical rollers 329a&min;, 329b&min; just discussed, rather than on angled edges
of the corner guides themselves as in Fig. 12.
Figs. 23 through 26 illustrate the resulting complete assembly, which
is drawn broken away at 399 for a view of the interior. The features that are
substantially the same as those in embodiments already discussed will not be described
again here; the system of reference-numeral prefixes and suffixes previously established
may be helpful in interpreting portions of these drawings.
Motors 341a, 341b are mounted within the stem casings 333a, 333b
respectively. Each motor shaft 343a, 343b carries a worm 344a, 344b. A cross-shaft
347b in the stem casing 333b carries and is keyed to a worm gear 345b to engage
the worm 344b; and also carries and is keyed to a pair of spur gears 346b, 346b&min;
that engage the ring gears 351b.
By means of this arrangement, the motor 341b drives the spurs 346b,
346b&min; -- through the worm 344b, worm gear 344b, and cross-shaft 347b -- to
run along the exterior teeth 352b of the ring gear 351b, and thereby to rotate
the stem 333b itself, and with it the "horizontal" disc 321b, relative to the
inner structure. Through a similar drive train the motor 341a on the stem 333a
of the "vertical" disc 321a rotates that disc relative to the inner structure.
If desired, one of the stems 333a can be eliminated and the associated
working head or the like flush-mounted or recessed in the corresponding vertical
ring 321a. The motor 341a too can be mounted within the disc, a smaller-diameter
ring gear 351a employed, and the spur gears 346a thereby recessed relative to
the exterior cylindrical surface of the ring 321a. These changes would permit the
vertical ring 321a to operate through more than one complete rotation -- except
that provision must be made to protect the flexible flux-transmission means against
damage by impingement on the horizontal ring 321b.
One way to do that is to take advantage of the extra clearance available
inside the vertical ring 321a, as I have generally suggested by analogy in discussion
of Fig. 4 (see the exposed inner-cylinder gap surface 19b in that drawing). To
provide such clearance, the vertical ring 321a can be made larger than the horizontal
ring 321b, or the two rings can simply be mounted with their centers slightly
Then, with careful design of the transmission-means harness 364 (Fig.
24) within the internal structure, the transmission means 364 can be rotated past
the vertical ring 321b. A coiled or automatically fed harness, for example, may
permit as many as two to four full rotations or even more; however, I have not
explored such potentialities in great detail.
Figs. 27 through 35 exemplify various interesting characteristics
of my invention. Fig. 27, which is a variant of the embodiment illustrated in Figs.
13 and 14, shows that four motors 240a1, 240a1&min;, 240a2, 240a2&min; can be
mounted to drive the "horizontal" ring, and if desired a like array of motors can
be mounted to drive the "vertical" ring, in applications requiring additional
None of these motors impairs the free motion of either ring, since
all eight motors are mounted to the inner guide structure and none is in the line
of motion of either stem. Even further motive force can be provided without changing
the geometry of the motors or of the system, simply by ganging additional motors
on the drive-shafts of any of the eight motors that are illustrated.
The motor 240a1&min; that appears in the upper right-hand quadrant
of the Fig. 27 assembly, driving the horizontal ring, is engaging the same ring
gear as the motor 240a1 in the upper left-hand quadrant. A single separate ring
can be installed in the lower half of the horizontal ring to accommodate two lower
motors 240a2, 240a2&min; driving that ring. Of course the same observations apply
equally to the vertical ring and its motors.
Besides illustrating where additional force-applying elements can
be installed, Fig. 27 also helps to clarify the more general point that the spaces
in the four quadrants (between the lines of motion of the two stems) are available
for installation of virtually any additional equipment, provided that it is installed
to the inner guide structure rather than to the rings. In fact, within those four
quadrants the guide structure need not be, or remain, an "inner" structure at all
-- since it can be extended far beyond the radii of the rings, beyond the radius
of at least one stem, and even beyond the radius of a working head or the like
installed on a stem.
Fig. 28 shows that two, three or even more joints can be arranged
in cascade -- that is, the output stem 433b1 of the first stage can double as the
input stem 433a2 of the second; and similarly for the common stem 433b2/433a3
interconnecting the second and third stages. As illustrated, a joint 422a1-422b1
that supports other joints 422a2-422b2, 422a3-422b3 can be made heavier in construction
and can be provided with additional power 440b1, 440b&min;1, etc. as may be appropriate.
A flux 466 can be delivered through all of the joints in series to
a flux-transmission-means termination or discharge device 465. Of course a flux
can also be utilized to control any of the three joints, or can be delivered from
any intermediate point along the system as desired.
Figs. 29 and 29a show that the crossed-disc guide structure of Figs.
7 through 12a can be combined with the stem-mounted motor arrangements of Figs.
20, 23 and 26. (A variation appearing in Figs. 29, 29a is that only one spur-and-ring-gear
train is used for each ring, rather than two as in Figs. 20 and 23.)
Conversely, Fig. 30 shows that the corner guide system of Figs. 15
through 19, and Figs. 21 and 23, can be combined with the side-mounted motor arrangements
of Figs. 12 through 14.
Figs. 31 through 34 illustrate an extremely inexpensive assembly,
related to that of Fig. 18, in which each ring is formed as a shallow "C" channel
922a, 922b (see cross-section in Fig. 32), bent into a horseshoe shape as shown
in Fig. 31, and fitted with an insert 933a, 933b that has a near-half-circle inner
end 923a&min;, 923b&min; and a rectangular outer end.
The corner guides have slotted edges 915a, 915a&min; as shown in
Fig. 33; and the inward-protruding flanges 921b, 921b&min; (Fig. 32) that give
the channel its "C" cross-section fit into these slots as shown in Fig. 34, to
serve as followers.
The rectangular outer ends of the two ring assemblies 921a-933a,
921b-933b serve as the stems. As will be appreciated, these stems are quite wide
along their direction of rotation, and accordingly limit the angular range of
rotation more than the stems in earlier-discussed embodiments.
Flux-transmission means can be passed through the straight access
holes 937a, 937b: these holes enter the central cavity off-center to help clear
the opposing rings in the straight or extended configuration of the joint; and
the rings are further apart, center-to-center, than in the previously discussed
embodiments -- so that the transmission means can bypass the opposing rings without
the need for routing around to the point diametrically opposite the stem. In the
assembled system, however, the transmission means will be visible where they pass
between the inner end of each access hole and the interior cavity of the joint.
If desired the "C" channels and inserts can be extended to serve
as long arms, the arms and the rings thus being in effect unitary. This system
can be applied in cascade as in Fig. 28 -- but using between each two adjacent
stages a single "C" channel that wraps around corner guides of
both stages and has its two cut-off ends abutting each other partway between.
The above-mentioned compromises in angular operating range and in
visibility of the transmission means inside the joint are tradeoffs in the interest
of an extremely economical assembly that is particularly suited to implementation
in lightweight construction for office or consumer applications such as a desk-mounted
Fig. 35 emphasizes the point made earlier, in reference to Fig. 27
and elsewhere, that the so-called "inner" guide structure can extend well beyond
the radii of either or both rings, and can be of entirely arbitrary shape. The
guide structure must provide the necessary guide surfaces -- either arcuate edges
or tracks, or a sufficient number of point contacts -- to constrain the rings
or other outer bodies to systematic movement.
Here the guide structure 1011/1013 is a rigid figurine. The guide
surfaces for the ring 1020a that appears to be angled in the drawing are provided
at the figure's waist 1015a1, left palm 1015a2, and right palm 1015a3. Those for
the ring 1020b that appears to be vertical are at the figure's neck and shoulders
1015b1, right knee 1015b2, left foot 1015b3 and buttocks 1015b4.
Despite use of this arbitrarily shaped guide structure, the Fig.
35 apparatus is a fully functioning joint, with unimpaired angular range of stem
rotation. Flux transmission is not readily provided by flexible means Passing
from the rings into and through the guide structure 1011/1013; but could be provided
by means of slip rings, brushes, or sliding fiber or tube connections.
Furthermore the invention has the following advantageous features:
- 1. the substantially circular part of each track is shaped substantially as
more than half of a circle;
another part of each guide has a substantially noncircular
the cutout slot in each guide extends from the substantially
noncircular part of that guide into the substantially circular part of the track
in that guide.
- 2. the substantially circular part of each track is shaped substantially as
more than half of a circle;
another part of each guide has a substantially noncircular
the cutout slot in each guide extends from the substantially
noncircular part of that guide into the substantially circular part of the track
in that guide, past the center of the circle of the substantially circular part
of that track; and within the substantially circular part the cutout slot is disposed
- 3. the guides are generally planar discs;
the slots of each guide pair are mutually substantially equal
in width and are mutually aligned; and
each pair is spaced apart so that the distance between the
outer surfaces of the two guides is, at least roughly, equal to the widths of the
slots in the other pair.
- 4. each guide has an edge, a section of which is shaped substantially as a
portion of a circle; and
said part of each guide that defines a track is said substantially
circular section of the edge of that guide;
the circular parts of the two guide edges of each guide pair
are substantially conaxial; and
the guide edges form said two mutually fixed pairs of substantially
- 5. the substantially circular part of each guide is shaped substantially as
an entire circle, except that the cutout slot extends substantially from a substantially
circular edge of the guide generally diametrally past the center of the guide.
- 6. flux-utilization means mounted to the body-constraining structure and connected
to receive flux from the flexible flux-transmission means;
whereby flux is transmitted by the flux-transmission means
from said at least one body to the flux-utilization means, through the hollow
enclosure, notwithstanding said rotational motion of the bodies relative to the
- 7. the flux-utilization means comprise motor means driven by the flux to power
said rotational motion of the bodies relative to the tracks.
- 8. the flexible flux-transmission means are connected to both bodies;
whereby flux is transmitted by the flexible flux-transmission
means from one body to the other, through the hollow enclosure, notwithstanding
said rotational motion of the bodies relative to the tracks.
- 9. flux-utilization means mounted on said other body and connected to receive
flux from the flexible flux-transmission means.
- 10. a base for supporting the bodies;
a first stem extending from said one body for mounting said
one body to the base; and
a second stem extending from said other body to support the
whereby, in said rotation of the bodies relative to the tracks:
said body-constraining structure rotates
within said one body and relative to the base, and
said other body rotates upon said body-constraining
wherein said rotational motion of the bodies relative to the
tracks is angularly limited substantially only by engagement of the second stem
with said one body and of the first stem with said other body.
- 11. the flux-utilization means comprise motor means mounted on the second stem,
and driven by the flux to power said rotational motion of said other body relative
to the body-constraining structure.
- 12. the corner guides are held in their array by substantially only the bodies
and followers; and the bodies are held in relative position for said systematic
mutual movement by substantially only the corner guides and tracks.
- 13. each corner guide comprises a pair of mutually angled plates, each plate
defining one of said circular-segment tracks.
- 14. each plate has an edge, a section of which is shaped substantially as a
segment of a circle; and
said part of each plate that defines a track is said substantially
circular section of the edge of that plate; and
the two circular-segment edges of each corner guide have mutually
- 15. flux-utilization means mounted to the body-constraining structure and connected
to receive flux from the flexible flux-transmission means;
whereby flux is transmitted by the flux-transmission means
from said at least one body to the flux-utilization means, through the hollow enclosure,
notwithstanding said rotational motion of the bodies relative to the tracks.
- 16 the flux-utilization means comprise motor means driven by the flux to power
said rotational motion of the bodies relative to the tracks.
- 17. each body has a central axis; and
the body-constraining structure comprises a pair of interconnected
a first one of the tracks being supported
by a first body, for rotation of the first track about the central axis of the
first body, and
a second one of the tracks supporting
a second body, for rotation of the second body about its own central axis;
whereby said systematic mutual movement comprises rotation
of each body about its own central axis, relative to the interconnected tracks.
- 18. means, associated with the body-constraining structure, for transmitting
a flux from one of the bodies.
- 19. the transmitting means transmit a flux from one of the bodies to the other
- 20. the force-applying device comprises a discrete motor; and
the transmitting means transmit a flux of a power-conveying
medium from said one of the bodies to power the motor.
- 21. the flux-transmitting means comprise a flexible transmission line, fixed
to said one of the bodies, for carrying the flux of power-conveying medium.
- 22. the body-constraining structure comprises a hollow portion for passage
of the transmission line;
whereby the flexible transmission line transmits power to
the motor through the hollow portion of the body-constraining structure, notwithstanding
said powered systematic mutual movement.
- 23. the body-constraining structure comprises two pairs of notched substantially
each disc defines a cutout slot;
the two discs of each pair are spaced apart, substantially
planar, and mutually parallel and conaxial, and the slots are mutually aligned;
the two pairs of discs are interfitted by insertion of each
pair into the slots of the other pair.
- 24. a stem connected to said at least one of the bodies, for attachment of
the body to an article;
wherein the motor is mounted to the stem.