Patent Publication Number: US-5893296-A

Title: Multiple rotatable links robotic manipulator

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to controlled motion mechanical members used as a mechanical manipulator and, more particularly, to a motion controllable mechanical manipulator which can be formed from repeated use of components of relatively few component types. 
     A strong desire for increased automation in the workplace, and a desire to increase the use of animated figures depicting animals, humans or other characters in entertainment and other situations, along with an increased ability to control such mechanical manipulators has led to substantial efforts in the development of robotics. As a result, substantial advances have occurred in many aspects of robotics. 
     Perhaps the most widely used controlled component in robotic systems is a mechanical manipulator, that portion of a robot used to change the position of orientation of selected objects engaged by that manipulator. In many instances, such mechanical manipulators are desired to have capabilities similar to those of the human wrist or shoulder, that is, exhibiting two or more degrees of freedom of motion. 
     Although a number of such mechanical manipulators have been developed which to a greater or lesser degree achieve some of these desires therefor, most have been relatively complicated devices requiring complicated components and difficult assembly procedures or both. Many, in addition, represent compromises in having relatively limited range, or singularities within the ranges, or other limitations in performance. Thus, there is a strong desire for a mechanical manipulator which can, under control of the user, position objects anywhere over at least a hemispherical surface without any singularities in the operation of the device in this range, and which can be made both reliably and inexpensively. 
     SUMMARY OF THE INVENTION 
     The present invention provides a controlled relative motion system comprising a base support, a pivot holder and a plurality of pivoting links. The pivoting links are rotatably coupled to both the base support and to members of the pivot holder to rotate about axes which extend in different directions for each of these rotatable couplings in a link typically in accord with specific geometrical arrangements, and in different directions from similar axes in another of such links. The pivot holder can serve as a further base for a second similar controlled motion member system, or the pivot holder can be linked with a second plurality of pivoting links to a manipulable support. Such a manipulable support can be a part of, or support for, further such systems, or both. These systems can be supported on rotatable mounting arrangements at the base supports or pivot holders. 
     Such systems can incorporate a variety of force imparting members to control movements of various ones of the pivoting links or pivot holder members. Such members may be electric motors or linear actuators, and may be connected to the system directly or through drive trains and the like. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 through 4 show perspective, elevation, plan and fragmentary views of an embodiment of the present invention, 
     FIG. 5 shows a top view of an alternative embodiment of the present invention, 
     FIGS. 6 through 8 show a perspective and two elevation views of an alternative embodiment of the present invention, 
     FIGS. 9 through 12 show various perspective views of the embodiment of the present invention shown in FIGS. 6 through 8, 
     FIGS. 13 through 15 show perspective, fragmentary and plan views of an alternative embodiment of the present invention, 
     FIGS. 16 through 22 show perspective views of alternative embodiments of the present invention, 
     FIGS. 23 and 24 show perspective and fragmentary views of an alternative embodiment of the present invention, 
     FIGS. 25 through 27 show perspective views of alternative embodiments of the present invention, 
     FIGS. 28A and 28B show partial fragmented elevation and partial plan views of an alternative embodiment of the present invention, and 
     FIGS. 29A and 29B show partial fragmented elevation and partial plan views of an alternative embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1, 2 and 3 show a first embodiment of a mechanical manipulator, or controlled member motion system, 10, which can have a very large output operating range in various configurations over which it is free of singularities, and which is operated by various force imparting devices directly or through various drive trains. FIG. 1 shows a perspective view of manipulator 10 with FIGS. 2 and 3 showing an elevation view and a top view thereof, respectively. Manipulator 10 is positioned on a mounting arrangement, 11, containing therein an electric motor arrangement, unseen in these figures, which can rotate mounting arrangement 11 in either the clockwise or counterclockwise direction as selected by the user to thereby carry the remainder of joint or manipulator 10 correspondingly with it in these directions. Directly supported on mounting arrangement 11 is a base support, 12, shown as truncated cylindrical shell structure though different geometrical shapes can be used. Support 12 has an opening, 13, extending vertically in these figures along the axis of radial symmetry for support 12 to parallel the outer curved sides thereof. Opening 13 extends through support 12 and from there through mounting arrangement 11 along the axis about which it is capable of rotating manipulator 10 so as to be capable of permitting some desired means extend therethrough such as electrical wiring, optical fibers or some mechanical arrangement, or some combination thereof. 
     Also shown supported directly on mounting arrangement 11 are a pair of rotary actuator support pedestals, 14, each of which is shown supporting an electric motor along with the direct mechanical interconnection between that electric motor and the remaining portions of manipulator 10. That is, a pair of electric motors, 15 and 16, are each mounted in the corresponding one of pedestals 14 by screws, 17, as can be better seen in FIG. 4 which is a fragmentary view of a portion of each of FIGS. 1, 2 and 3 with parts of this fragmentary view shown in cross section. Electric motor 16 has a shaft, 18, extending from the rotor thereof, which is directly affixed in an opening of a crank arm, 19. Crank arm 19 is directly affixed to a pivoting link, 20, by a further screw, 21. Rotation by the rotor in electric motor 16 clockwise or counterclockwise causes shaft 18 to rotate in a corresponding angular direction which in turn causes crank arm 19 to correspondingly rotate. 
     Such rotations by crank arm 19 forces pivoting link 20 to in turn rotate one way or the other about a pin, 22, on a pair of bearings, 23, around a rotation axis extending through pin 22 that is more or less perpendicular to the length of link 20. Shaft 22 is directly affixed in an opening in base support 12, and could be a pivot screw rather than a pin. Such a pivot screw is threaded at the end thereof opposite the screw head only a relatively short distance in from that end to permit its being screwed firmly into base support 12 but only a fixed distance therein to assure a selected length of the screw is exposed outside support 12 The surface of this exposed portion of the screw from support 12 to the screw head is smooth especially if no bearing or bushing is used between this screw and pivoting link 20 (lubrication at the least would be likely to be used in this situation). Typically, there will be used either bearing set 23 or a bushing between pin or pivot screw 22 and pivoting link 20. 
     An identical electric motor rotational drive system for forcing rotational motion of another pivoting link is provided in connection with electric motor 15. As seen in FIGS. 1, 2 and 3, a crank arm, 19&#39;, is affixed to the rotor shaft of motor 15 (this mechanical connection is unseen in FIGS. 1, 2 and 3) with the other end of crank arm 19&#39; being affixed by screw, 21&#39;, to a further pivoting link, 20&#39;, rotatably connected to base support 12. Thus, again, rotation of the rotor of electric motor 15 in either the clockwise or counterclockwise direction forces pivoting link 20&#39; to correspondingly rotate in either a clockwise or counterclockwise direction. Pivoting link 20&#39; can rotate on bearings about a pin or pivot screw, 22&#39;, not seen in these figures, affixed to base support 12, and again around an axis extending therethrough more or less perpendicular to the length of link 20&#39;. 
     Pivoting links 20 and 20&#39; are two pivoting links in a plurality of lower pivoting links in manipulator 10, this lower plurality further including two other pivoting links, 20&#34; and 20&#39;&#34;. These last two pivoting links are each capable of rotating on bearings about a corresponding one of pins or pivot screws, 22&#39; and 22&#39;&#34;, respectively, with the corresponding axis of rotation extending therethrough substantially perpendicular to the length of links 20&#34; and 20&#39;&#34;. Pins or pivot screws 22&#34; and 22&#39;&#34; are affixed to base support 12, and are seen in part in FIGS. 1 and 2. Each of pins or pivot screws 22, 22&#39;, 22&#34; and 22&#39;&#34; is affixed to base support 12 such that the corresponding one of the plurality of lower pivoting links rotatably coupled to base support 12 thereby rotates about an axis therethrough that intersects, and is perpendicular to, the axis of radial symmetry of support 12, with these rotation axes being separated from adjacent ones by equal angles measured about the symmetry axis, here 90°. 
     The lower plurality of pivoting links 20, 20&#39;, 20&#34; and 20&#39;&#34;, in addition to each having an end thereof being rotatably connected to base support 12 as described above, also each have the opposite end thereof rotatably connected by four further pins or pivot screws, 24, 24&#39;, 24&#34;and 24&#39;&#34;, to a pivot holder comprising four individual and separated pivot holder members, 25, 25&#39;, 25&#34; and 25&#39;&#34;, which have no direct connections therebetween. Each of these pivot holder members is formed as a truncated portion of a cylindrical shell about an axis of radial symmetry, and each is shown with a corresponding one of a set of holes, 26, 26&#39;, 26&#34; and 26&#39;&#34;, extending therethrough parallel to the outer curve surface thereof along the shell axis of radial symmetry. The outer curved surface of each such pivot holder member shell is pierced by its corresponding one of pins or pivot screws 24, 24&#39;, 24&#34; and 24&#39;&#34; in its being affixed therein. Each such pin or pivot screw has the end of the corresponding one of the lower plurality of pivoting links 20, 20&#39;, 20&#34; and 20&#39;&#34; coupled thereto so as to be able to rotate thereabout on bearings with the axis of rotation of this link about such pin or pivot screw being more or less parallel to the length of the link and intersecting the shell axis of radial symmetry. 
     The axis of rotation of each of the lower plurality of pivoting links 20, 20&#39;, 20&#34; and 20&#39;&#34; through a corresponding one of pins or pivot screws 24, 24&#39;, 24&#34; and 24&#39;&#34; in being rotatably coupled to a corresponding one of pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34;, and the axis of rotation of each of these links through a corresponding one of pins or pivot screws 22, 22&#39;, 22&#34; and 22&#39;&#34; in being rotatably coupled to base support 12 are, in each link instance, perpendicular to planes that intersect one another at substantially right angles. These rotation axes for each of these links are also oriented in directions differing from those in an adjacent link, i.e. the next link thereafter around base support 12. This allows pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34; to be moved by the corresponding pivoting links substantially with respect to base support 12, but for the same length links these pivot holder members will always be in a plane common thereto, and will move about a circle in such planes. 
     Although pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34; are shown in these figures as truncated portions of cylindrical shells, this shape is not required but instead other geometrical shapes could be used. One such shape clearly could be just the inside half these cylindrical shells which could result from dividing each of them vertically along the axis of radial symmetry. Another alternative would be a triangular block having a side thereof substantially perpendicular to the axis of rotation about which the pivoting link from the lower plurality thereof can rotate in being rotatably coupled thereto by its corresponding pin or pivot screw. 
     Manipulator 10 is shown in these figures having a further upper plurality of pivoting links. A corresponding one of this plurality is rotatably coupled to each of pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34; by a corresponding one of a further set of pins or pivot screws, 27, 27&#39;, 27&#34; and 27&#39;&#34;, again which pierce the outer curved shell surface of that member in being affixed therein. The axis of rotation of the corresponding one of this upper plurality of pivoting links, in being able to rotate about its pin or pivot screws 27, 27&#39;, 27&#34; and 27&#39;&#34;, is directed so as to be more or less parallel to the length of the link and to intersect the axis of radial symmetry of the corresponding one of pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34;. As a result, there is a corresponding one of a set of angles, 28, 28&#39;, 28&#34; and 28&#39;&#34;, of a selected angular magnitude between the axis of rotation of the pivoting link from the lower plurality thereof rotatably connected to each pivot holder member and the axis of rotation of the one of the upper plurality of pivoting links also rotatably connected thereto as shown in these figures. The selection of the magnitude of each of angles 28, 28&#39;, 28&#34; and 28&#39;&#34; effects the capabilities of manipulator 10 as will be described below. For any selected angle, increasing the diameter of the outer surface of the truncated cylindrical shell serving as pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34; will result in shortening the length of the pivoting links rotatably connected thereto from both the upper and the lower pluralities thereof. 
     Another set of pins or pivot screws, 29, 29&#39;, 29&#34; and 29&#39;&#34;, are each used at the opposite end of a corresponding one of the upper plurality of pivoting links, 30, 30&#39;, 30&#34; and 30&#39;&#34;. If manipulator 10 is constructed symmetrically above and below a plane including the axes of radial symmetry of each of pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34; (a horizontal plane in FIG. 2), i.e., angles 28, 28&#39;, 28&#34; and 28&#39;&#34; in these figures being bisected by such a common plane, the upper plurality of pivoting links 30, 30&#39;, 30&#34; and 30&#39;&#34; can be identical in construction with each other and with each of the lower plurality of pivoting links 20, 20&#39;, 20&#34; and 20&#39;&#34;. Although this is a significant economic factor in manufacturing significant numbers ofjoint or manipulator 10, this symmetry is not required for successful operation of such manipulators. However, the nature of the positioning of the output structure in such manipulators for a given rotation of the rotor shafts of motors 15 or 16 will change with differences in the portions of angles 28, 28&#39;, 28&#34; and 28&#39;&#34; above and below the horizon. Also, the lengths of pivoting links in the upper and lower pluralities thereof need not all be the same to have successful operation of manipulator 10 but, again, the pattern of the positioning of this output structure will change depending on such differences. 
     The output structure which is controlled in manipulator 10 by motion of the rotors of electric motors 15 and 16 has a hole, 31, provided therethrough to form a cylindrical shell resulting in a manipulable support, 32, forming this structure. Again, geometrical shapes other than such a cylindrical shell can be used, and again various items can be extended through opening 31 such as electrical wiring or optical fibers or, in this output situation, a further mechanical device supported on support 32, or some combination of such features or other alternatives. Each of pivoting links 30, 30&#39;, 30&#34; and 30&#39;&#34; in the upper plurality thereof is rotatably coupled by a corresponding one of pins or pivot screws 29, 29&#39;, 29&#34; and 29&#39;&#34; to manipulable support 32. Here too, each of pins or pivot screws 29, 29&#39;, 29&#34; and 29&#39;&#34; is affixed to support 32 such that the corresponding one of the plurality of upper pivoting links rotatably coupled to manipulable support 32 thereby rotates about an axis therethrough that intersects, and is perpendicular to, the axis of radial symmetry of support 32, with these rotation axes being separated from adjacent ones by equal angles measured about the symmetry axis, here again 90° because of the presence of four pivot links. Although the rotation axes of the pivoting links at the rotary couplings thereof to supports 12 and 32 are described as making equal angles with adjacent ones thereof as they occur about those supports, these angles need not be identical about either support, nor identical about one support with those about the other, to be able to position support 32 over a substantial angular range, though providing substantially such identities is often convenient. 
     The axis of rotation of such a one of pivoting links 30, 30&#39;, 30&#34; and 30&#39;&#34; in the upper plurality thereof about its pin or pivot screw coupling it to support 32 extends through that pin or screw more or less perpendicular to the direction of the length of that link, and substantially parallel to the axis of rotation about the pin or pivot screw rotatably coupling the corresponding one of pivoting links 20, 20&#39;, 20&#34; and 20&#39;&#34; in the lower plurality thereof to base support 12. The correspondence here between upper and lower plurality pivoting links is established by each being coupled to the same one of pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34;. Again here as for links in the lower plurality thereof, the axis of rotation of a pivot link 30, 30&#39;, 30&#34; or 30&#39;&#34; in the upper plurality thereof about its corresponding one of pins or pivot screws 27, 27&#39;, 27&#34; or 27&#39;&#34; is substantially perpendicular to a plane which intersects at substantially right angles that plane which is substantially perpendicular to the axis of rotation of that link about its corresponding one of pins 29, 29&#39;, 29&#34; or 29&#39;&#34;. 
     If crank arms 19 and 19&#39; are disconnected from the corresponding ones of pivoting links 20 and 20&#39; by removing corresponding screws 21 and 21&#39;, motors 15 and 16 would no longer be capable of operating joint or manipulator 10 to position manipulable support 32 at a desired position. However, in these circumstances, should the rotational driving system for rotating mounting arrangement 11 be activated, the system shown in FIGS. 1, 2 and 3 will operate as a flexible joint with manipulable support 32 following the rotation of mounting arrangement 11 and base support 12 to transmit that rotational motion to manipulable support 32 without requiring supports 12 and 32 to be axially aligned, i.e., the axis of radial symmetry of one can be at a substantial angle with respect to the radially symmetrical axis of the other. 
     The various structural components of joint or manipulator 10 described in connection with FIGS. 1 through 4 above are typically formed of a metal or metals, or alloys thereof, appropriate for the intended use, i.e. perhaps stainless steel for a medical use, aluminum or titanium where weight is a primary concern, etc. Many or all of these components could molded polymeric materials instead. 
     The top view of joint or manipulator 10 shown in FIG. 3 indicates that pivoting links 30, 30&#39;, 30&#34; and 30&#39;&#34; in the upper plurality thereof are assembled to be directly over the corresponding ones (connected to the same pivot holder member) of pivoting links 20, 20&#39;, 20&#34; and 20&#39;&#34; in the lower plurality thereof. That is, the pivoting links in the lower plurality thereof cannot be seen in FIG. 3 because the pivoting links in the upper plurality thereof are directly over them, requiring each combination of corresponding pivoting links from the upper and lower pluralities thereof to be both rotatably coupled to the same side of base support 12 and to the same side of manipulable support 32. This assembly pattern for the structure in manipulator 10 is not necessary, however, as each such combination can instead have the pivoting link from the upper plurality thereof and the pivoting link from the lower plurality thereof assembled on opposite sides of base support 12 and manipulable support 32 as is shown in FIG. 5. This results in a more even distribution of the pivot link masses about the central axis of joint or manipulator 10 extending toward the viewer through opening 31 and passing through unseen opening 13 there below for balance, and does not significantly affect the performance of the manipulator in positioning support 32 . 
     In a further alternative, a perspective view incorporating the configurational change shown in FIG. 5 is shown in FIG. 6 that corresponds to the perspective view shown in FIG. 1, and an elevation view for the FIG. 6 configuration is shown in FIG. 7 corresponding to the elevation view shown in FIG. 2. An alternative elevation view for the configuration shown in FIG. 6 is shown in FIG. 8 based on a shift of 45° in the point of view from that taken in FIG. 7. 
     A change in the configuration of the version of joint or manipulator 10 shown in FIGS. 6, 7 and 8 from the configuration shown in FIG. 5 is based on the reversal in the earlier choice of which link in a combination of two corresponding pivoting links rotatably coupled to a pivot holder member is chosen to extend from that member to base support 12 and manipulable support 32. That is, the pivoting links extending from each pivot holder member which were in the lower plurality of pivoting links in the examples shown in FIGS. 1, 2, 3 and 5 are now in the upper plurality in FIGS, 6, 7 and 8, and vice versa. This change, like the previous change in configuration in no longer having the pivoting links in the upper lower pluralities directly over one another, causes no limitation in the capabilities of manipulator 10 for positioning manipulable support 32 in any angular position desired. That is, manipulable support 32 can be placed in a particular desired angular position whether the configuration is that shown in FIGS. 1 through 3, or in the alternative configuration shown in FIG. 5, or in the further alternative configuration shown in FIGS. 6 through 8 resulting from particular patterns of assembling pivoting links to pivot holder members, and to base and manipulable supports 12 and 32. The designations used for the pivoting links in the upper and lower pluralities thereof in FIGS. 6 through 8 have not been changed because of the inconsequentiality of these assembly differences. 
     Finally, a further change in configuration of joint or manipulator 10 is shown in FIGS. 6 through 8 from the configurations shown in FIGS. 1, 2, 3 and 5, that change being the substitution of a motor driven, gear based drive train for directing motion of pivoting links in the lower plurality thereof for the direct connection of electric motors 15 and 16 to these links for that purpose. Thus, electric motor 15 is now carried in mounting arrangement 11 in FIGS. 6 through 8, and unseen in these figures, but an extension of its rotor shaft with a bevel gear affixed to the end thereof can be seen in these figures extending upward through mounting arrangement 11. This extended shaft and bevel gear affixed thereto form a combination together designated 15&#39;. A further bevel gear, 15&#34;, engaged with this first bevel gear, is affixed to pivoting link 20&#39; about pin or pivot screw 22&#39; so this link can again be rotated clockwise or counterclockwise about pin or pivot screw 22&#39; by rotation of the rotor shaft of unseen electric motor 15. Similarly, motor 16 is unseen in these figures in being supported under mounting arrangement 11, but an extension of its rotor shaft together with a bevel gear affixed on the end thereof as a combination, 16&#39;, engages a further bevel gear, 16&#34;, affixed to pivoting link 20 of the lower plurality of pivoting links about pin or pivot screw 22. Here too, rotation of the shaft of electric motor 16 either clockwise or counter clockwise allows rotating pivoting link 20 upward or downward about pin or pivot screw 22. 
     FIGS. 9 and 10 show perspective views of joint or manipulator 10 configured as in FIGS. 6 through 8 after rotation of shaft and gear combination 16&#39; rotating so as to position manipulable support 32 at approximately 45° down from the vertical position thereof in FIGS. 6 through 8 in a vertical plane containing the rotation axis extending through pin or pivot screw 22&#39; and passing through shaft and bevel gear combination 15&#39;. Such motion would result from the rotor of unseen motor 16 rotating shaft and bevel gear combination 16&#39; in a clockwise direction as seen in the figures with no rotation of the rotor of unseen motor 15. In FIG. 9, pivot holder member 25, and the ends of pivoting links 20 and 30 rotatably coupled thereto, have rotated upward from the positions they were in when manipulable support 32 was in the vertical position thereof shown in FIGS. 6 through 8 to enable support 32 to reach the position therefor shown in that figure. Similarly, pivot holder member 25&#34;, and the ends of pivoting links 20&#34; and 30&#34; rotatably coupled thereto, have rotated downward from the positions they were in when manipulable support 32 was in the vertical position therefor. 
     The rotation of these structural members and support 32 occurs primarily about a base center of rotational motion located at the intersection of the rotational axes through each of pins or pivot screws 22, 22&#39;, 22&#34; and 22&#39;&#34; on the axis of radial symmetry of the truncated cylindrical shell forming base support 12. This rotation of these structures and support 32 occurs also with a significant rotation of pivoting link 30&#39; and pivot holder member 25&#39; about pivoting link 20&#39;, and of pivoting link 30&#39;&#34; and pivot holder member 25&#39;&#34; about pivoting link 20&#39;&#34;, but without much movement of pivoting links 20&#39; and 20&#39;&#34; themselves because of the relatively little lateral movement required of the base of support 32 to which these links are coupled for that support to achieve the position therefor shown in FIG. 9. 
     However, as manipulable support 32 passes the location therefor shown in FIG. 9 in being rotated downward over shaft and gear combination 15&#39;, the lateral component of movement of the base portion of manipulable support 32 increases requiring corresponding lateral movements of pivoting links 30&#39; and 30&#39;&#34; therewith in view of their being rotatably coupled to support 32 by pins or pivot screws 29&#39; and 29&#39;&#34;. As can be seen in FIG. 10, this required lateral movement over shaft and gear combination 15&#39; of these coupled ends of pivoting links 30&#39; and 30&#39;&#34; requires that pivot holder members 25&#39; and 25&#39;&#34; and the ends of pivoting links 20&#39; and 20&#39;&#34; rotatably coupled thereto also rotate upward to facilitate this needed lateral movement by the ends of pivoting links 30&#39; and 30&#39;&#34; rotatably coupled to manipulable support 32. Such an arrangement, as can be seen in FIG. 10, allows manipulable support 32 to move from pointing vertically upward in FIGS. 6 through 8 to pointing in a direction that is around 45° above the horizontal as shown in FIG. 9, and then continue such movement to eventually point in a direction that is on the order of 45° below the horizontal. 
     Around this point in the motion of support 32, further downward rotation thereof is prevented by pivoting links 30&#39; and 30&#39;&#34; coming against pivoting link 30 to cause interference therebetween (of course, for different shaped structural components some other interference could occur such as between the pivot holding members to instead be the cause of termination of such downward motion). As this rotation is occurring and going from the position of manipulable support in FIG. 9 to that shown in FIG. 10, a significantly increased rotation occurs about a second or manipulable center of rotational motion located at the intersection of the axis of rotations passing through pins or pivot screws 29, 29&#39;, 29&#34; and 29&#39;&#34; on the radial axis of symmetry of manipulable support 32. During the movement of manipulable support 32 from the vertical position shown in FIGS. 6 through 8 over shaft and gear combination 15&#39; to the positions shown in FIGS. 9 and 10, pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34; remain in a common plane although the plane which changes its orientation and space with each increment of motion of support 32. 
     The situation of the structural members of joint or manipulator 10 changes somewhat when the downward movement of manipulable support 32 from the vertical position shown in FIGS. 6 through 8 is directed in a vertical plane that does not pass through two of pins or pivot screws 22, 22&#39;, 22&#34; and 22&#39;&#34; as occurs when the downward motion of manipulable support 32 was over shaft and gear combination 15&#39; so as to be in a plane passing through pins or pivot screws 22&#39; and 22&#39;&#34;. In this latter situation, the initial movement of manipulable support 32 involved the upward movement of pivot holder member 25 and the ends of pivoting links 20 and 30 coupled thereto, and the downward motion of pivot holder member 25&#34; and the ends of pivoting links 20&#34; and 30&#34; coupled thereto. There was little initial movement of either of pivoting links 20&#39; and 20&#39;&#34;; rather, there was primarily rotation about those pivoting links of pivoting links 30&#39; and 30&#39;&#34; along with pivot holder members 25&#39; and 25&#39;&#34;. 
     If, instead, the motion of manipulable support 32 from a vertical position downward occurs in the vertical plane which is at a 45° angle with respect to a plane intersecting pins or pivot screws 22&#39; and 22&#39;&#34;, i.e., a plane 45° from such a plane so as to occur halfway between pins or pivot screws 22&#39; and 22&#34;, all of the pivoting links in both the lower and upper pluralities thereof immediately show significant movement in correspondence with the start of this movement by support 32. Such a motion would result from the rotors of both unseen motors 15 and 16 rotating so as to rotate both shaft and bevel gear combination 15&#39; and shaft and bevel gear combination 16&#39;, respectively, equally in the clockwise direction as seen in the figures. The results of such movements are shown in FIG. 11 for reaching a first selected position in the movement of support 32, the combination of pivot holder member 25 and the ends of pivoting links 20 and 30 coupled thereto, along with the combination of pivot holder member 25&#39; and the ends of pivoting links 20&#39; and 30&#39; coupled thereto, having both moved upward to allow moving manipulable support 32 to approximately 45° downward from the initial vertical position shown therefor in FIGS. 6 through 8. On the other hand, the combination of pivot holder member 25&#39;&#34; and the ends of pivoting links 20&#39;&#34; and 30&#39;&#34; coupled thereto, along with the combination of pivot holder member 25&#34; and the ends of pivoting links 20&#34; and 30&#34; coupled thereto, have both moved downward to accommodate this motion of support 32. 
     These motions occur because, initially, of the lateral movement component of the base of manipulable support 32, which must be followed by each of the upper plurality of pivoting links 30, 30&#39;, 30&#34; and 30&#39;&#34; rotatably coupled thereto, thereby requiring the first two combinations to move upward and the second two combinations to move downward in accommodating that movement. The rotation about the manipulable center of motion increases as manipulable support 32 is moved further downward from the position shown therefor in FIG. 11 in the vertical plane indicated above to reaching the position shown therefor in FIG. 12 on the order of 45° below the horizontal. The downward motion of manipulable support 32 in this plane again is ended by interference occurring in the structural members, typically the coming together of pivoting links 30 and 30&#39;. 
     Again, over the range of motion of manipulable support 32 from the vertical position shown therefor in FIGS. 6, 7 and 8 through the position shown in FIG. 11 to the position reached in FIG. 12, pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34; remain in a common plane though one changing in space with every movement of support 32. Such a relationship will be maintained even if the angles 28, 28&#39;, 28&#34; and 28&#39;&#34; each have a larger though identical portion thereof on one side of such a common plane than on the other so as to result in the pivoting links in the upper plurality thereof being of a common length but differing from that of the common length of the pivoting links in the lower plurality thereof. Where the links in the upper plurality or lower plurality differ among the members thereof as well as differing from those in the other plurality because of differing angles at the pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34; between the rotational axes of the pins or pivot screws 24, 24&#39;, 24&#34; and 24&#39;&#34; and the rotational axes of the corresponding ones of pins or pivot screws 27, 27&#39;, 27&#34; and 27&#39;&#34;, manipulable support 32 can still be positioned over a useful angular range but such a common plane may not exist for all of pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34; during motions over that range. 
     Motions of manipulable support 32 from the vertical position therefor shown therefor in FIGS. 6 through 8 that are downward in vertical planes that are intermediate to those vertical planes in which such downward motion occurred in FIGS. 9 and 10, on the one hand, and in FIGS. 11 and 12, on the other, results in corresponding intermediate arrangements of the pivoting link and pivot holder member combinations described above in connection with the motion in the vertical plane connected with FIGS. 11 and 12. That is, as the selection of the vertical plane of downward motion for manipulable support 32 moves from the plane involved in FIGS. 11 and 12 toward the plane involved in FIGS. 9 and 10, or as manipulable support 32 in the position shown therefor in FIG. 12 moves directly toward the position shown therefor in FIG. 10, the combination of pivot holder member 25&#34; and the ends of pivoting links 20&#34; and 30&#34; coupled thereto remains in the rotated downward position but the combination of pivot holder member 25&#39;&#34; and the ends of pivoting links 20&#39;&#34; and 30&#39;&#34; coupled thereto is increasingly elevated. At the point where manipulable support 32 as directed to move reaches the position shown therefor in FIG. 10, this latter combination involving pivot holder member 25&#39;&#34; and the ends of pivoting links 20&#39;&#34; and 30&#39;&#34; coupled thereto reaches the full upward position therefor shown in FIG. 10. Similar results occur for all of the other vertical planes of downward motion of manipulable support 32 positioned around base support 12. 
     Even if angles 28, 28&#39;, 28&#34; and 28&#39;&#34; are chosen to be equal to one another and symmetrical about the common plane of the pivot holder members, different choices for that equal angular value will affect the capabilities of joint or manipulator 10 insofar as the extent thereof and the angular range of motion of manipulable support 32. Thus, a relatively smaller value for those angles but equal for each, such as the 45° choice made in the examples shown in FIGS. 1 through 12, will result in a relatively larger diameter circle on which pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34; can be positioned in the common planes they are in for corresponding positions of manipulable support 32. On the other hand, smaller angles generally tend to give a larger angular range of operation for manipulable support 32 because the coming together, or interference, of members 30, 30&#39;, 30&#34; and 30&#39;&#34; of the upper plurality of pivoting links near their rotary couplings to pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34; are avoided over a larger angular position range of support 32 since they are farther from one another in the initial vertical position of that support. 
     Generally, just the opposite conditions occur for choices of the equal angle which are relatively large, such a the choice of 90°, or even more such as 120°. Such choices lead to a relatively smaller diameter circle on which pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34; can be positioned in the common planes they share for corresponding positions of manipulable support 32, but interference between the structural members will occur for much less movement of manipulable support 32 to thereby limit the angular range in which manipulable support 32 can operate to being at latitudes well above the horizon to say nothing of being able to reach angular positions below the horizon as can manipulator 10 in the examples shown in FIGS. 10 and 12. 
     A further aid in increasing the angular operating range or positioning of manipulable support 32 is removing a pivoting link from the upper plurality thereof, its corresponding pivot holder member and the corresponding lower pivoting link, and symmetrically repositioning the remaining links and members about the supports. Removing some such components from manipulator 10 results in there being fewer such components remaining therein to interfere with one another which generally tends to increase the range of motion or positioning available to manipulable support 32. One example of such a reduced number of these pivot holder member and upper and lower pivoting links combinations is shown in FIGS. 13, 14 and 15. In this example, there are just three pivoting links in the upper plurality thereof and, similarly, just three pivoting links in the lower plurality thereof. 
     The odd number of pivoting links in the upper and lower pluralities thereof, distributed with equal angle separation about supports 32 and 12 in being rotatably coupled thereto, results in there being no pair of orthogonal axes with respect to this three pivot holder member joint or manipulator 10 shown in these figures along which the imposition of control forces will provide complete control of that manipulator as was possible with the examples having four pivoting links in the upper and lower plurality thereof as shown in FIGS. 1 through 12. Even if one combination of pivot holder member and the two connected pivoting links was moved to have the rotational axes of the two links with respect to the two supports orthogonal to similar axes of one of the other combinations so the angles between all three were no longer equal, the imposition of control forces along the orthogonal sets of such axes will be insufficient to provide adequate to provide complete control. Although there will be sufficient control to move the manipulable center of rotational motion in manipulable support 32 anywhere in a suitable angular range in either situation, there will be insufficient control to also maintain the desired orientation of the top or output surface of manipulable support 32. Such operating capability and such limits on control will usually be present even if different angular relationships are used between the rotational axes of upper level pivoting links in being coupled to manipulable support 32 than are used between the rotational axes of lower level pivoting links in being coupled to base support 12. 
     Thus, a third electric motor, 35, is added to the example shown in FIGS. 13, 14 and 15 because three electric motors, or three force imparting means of some kind operating through corresponding drive trains, are required to enable the positioning of the output support, or manipulable support 32, over the full possible angular range with good stability in reaching and maintaining a desired position therein. The same numerical designations are used in connection with the examples shown in FIGS. 13, 14 and 15 as have been used in the examples shown in FIGS. 1 through 12, but with the components having numerical designators including triple primes in these earlier examples being omitted in FIGS. 13, 14 and 15. 
     As can be seen in FIG. 14, the direct coupling of electric motor 16 to pivoting link 20 is the same for the system of FIGS. 13, 14 and 15 as it was for the system of FIGS. 1 through 4. This same motor-load coupling system is used in directly coupling electric motor 35 to pivoting link 20&#34; through using an added crank arm, 36, in the same position with respect to that motor and link as crank arm 19 is to the motor and link shown in FIG. 14. Pivoting links 20, 20&#39;, and 20&#34; in the lower plurality thereof, in addition to being directly coupled to the corresponding electric motors, are again rotatably coupled to base support 12 by pins 22, 22&#39; and 22&#34; being affixed in that support so as to permit these pivot arms to rotate thereabout on bearings not seen except for bearing set 23 seen in FIG. 14. Again, pivot screws could instead be used rather than pins, and in either case, pivot screws or pins 22, 22&#39; and 22&#34; are affixed in base support 12 such that the axis of rotation for the pivoting links rotating thereabout on bearings extends along the long axis of the pin or pivot screw. These pins or pivot screws 22, 22&#39; and 22&#34; are also affixed in base support 12 such that these rotation axes intersect one another at the axis of radial symmetry of the truncated cylindrical shell forming base support 12 (base center of rotational motion) with there being equal angles between these rotation axes, here 120°. 
     Similarly, pins or pivot screws 29, 29&#39; and 29&#34; are used in rotatably coupling pivoting links 30, 30&#39; and 30&#34; to manipulable support 32 with the axis of rotation of these pivoting links about these pins or pivot screws extending along the long axis of such pins or pivot screws. These axes, too, are separated by equal angles of 120° and intersect at the axis of radial symmetry of the truncated cylindrical shelf serving as manipulable support 32 (manipulable center of rotational motion). 
     The rotary couplings of lower plurality pivoting links 20, 20&#39;, 20&#34; and 20&#39;&#34; to base support 12 and to pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34;, and the rotary couplings of upper plurality pivoting links 30, 30&#39;, 30&#34; and 30&#39;&#34; to these same pivot holder members and to manipulable support 32, have in each instance above been described as being provided based on either pins or pivot screws. Such rotary couplings have been shown completed by the pivoting links involved being capable of pivoting around those pins or pivot screws on bearings, or possibly on bushings, or in some instances with the pivoting link surface directly against the pin or pivot screw surface with perhaps some lubrication therebetween. Such rotary coupling arrangements, however, are not the only possibilities. A further possibility is the use of hinges with two side members therein for affixing to the components that are to rotate with respect to each other with these side members being rotatably coupled to one another by a hinge pin which may be a separate component or integral with one of the members. Use of a hinge in joint or manipulator 10 has one side member of the hinge affixed to, or integral with, the pivoting link of interest, and with the other side member of the hinge being affixed to, or integral with, any of base support 12, pivot holder member 25, 25&#39;, 25&#34; and 25&#39;&#34;, or to manipulable support 32 as appropriate. In the affixing, or integrating, of the side members of a hinge being used to assemble pivoting links to such other members of joint or manipulator 10, the hinge is arranged so that the result is the hinge pin being positioned along the same axis as the rotational axis that extended through the pin or pivot screw in the earlier forms of the rotary coupling described above. 
     A further possibility in a hinged rotary coupling is the use of a so called &#34;living hinge&#34; in which the two sides of the hinge are each integral with one of the two corresponding structural members being hinged together to accomplish the affixing of the hinge sides thereto, and the hinge pin is provided by a thin portion of the material forming the hinge being continuously extended between these two corresponding structural members rather than by a separate pin. A joint or manipulator 10 embodying such &#34;living hinge&#34; structures is shown in FIG. 16. In this figure, structures having the same purpose as similar purpose components in the joints or manipulator examples previously given have retained the same numerical designations here as were used in the earlier examples. This is so even though there are significant structural differences in the structural members used in FIG. 16 as compared to similar purpose components used in the earlier examples because of the use of &#34;living hinges&#34; in the FIG. 16 system in place of the pins or pivot screws used in the earlier examples. 
     Thus, an output shaft, 15&#39;&#34;, extending from a linear actuator not shown in FIG. 16 (perhaps having one end thereof mounted on a mounting arrangement also not shown in FIG. 16) is used to rotate pivoting link 20&#39; about &#34;living hinge&#34; 22&#39; that connects that pivoting link to base support 12. In the same manner, an output shaft, 16&#39;&#34;, extending from a linear actuator not seen in FIG. 16 is used to rotate pivoting link 20 about &#34;living hinge&#34; 22 connecting it to base support 12. These &#34;living hinges&#34; replace corresponding pins or pivot screws 22&#39; and 22 in previous examples. Such &#34;living hinges&#34; are also provided in the structure of FIG. 16 for connecting pivoting links 20&#34; and 20&#39;&#34; to base support 12 to rotate thereabout although these hinges are unseen in that figure. The other &#34;living hinges&#34; provided in place of the pins or pivot screws used in the previous examples in FIGS. 1 through 15 are designated with the numerical designations in FIG. 16 that were used for such pins or pivot screws in the previous examples. 
     As can be seen, pivoting links 20, 20&#39;, 20&#34; and 20&#39;&#34; in the lower plurality thereof are formed as extended flat sheets with a more or less central ridge embossed therein for strength. Alternative to such a ridge for strengthening would be an edge flange along the long sides of the link bent at a significant angle with respect to the rest of the sheet, or a rigid backing strip affixed to the center of the link sheet, or the like. Pivoting links 30, 30&#39;, 30&#34; and 30&#39;&#34; in the upper plurality thereof are provided in the same manner. Pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34; are also provided as flat sheet portions. Base support 12 and manipulable support 32 are each provided as truncated cylindrical shell portions affixed to a four-arm cross with the arms being 90° apart and approximately the same length, the cylindrical shell portions being affixed to the region where these arms cross one another. 
     The construction of the upper and lower pluralities of pivoting links, the pivot holder members, and the &#34;living hinges&#34; therebetween used in place of pins or pivot screws in the structure of FIG. 16 allows the structure to be formed relatively inexpensively. One possibility is stamping, cutting or molding of upper and lower halves of joint or manipulator 10 with a dividing line being the intersection of pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34; with the horizontal plane common thereto at the point midway therein between the upper and lower pivoting link rotatably attached thereto by corresponding &#34;living hinges&#34;. Each such half so formed can then be assembled into the structure of joint or manipulator 10 in FIG. 16 by merely welding the two halves of each pivot holder member together if the material chosen is a weldable metal, or by adhering the two sides of each pivot holder member together if the material is a polymer or some other material suitably joined by adhesion. If, instead of the dividing line being in a common horizontal plane, the divide is made at the living hinges, and these hinges are made as bendable in one direction as the other, identical upper and lower halves can be made to reduce the number of different components used in the assembled manipulator. A further possibility is the provision of a three dimensional mold to form joint or manipulator 10 of FIG. 16 as a complete entity in a single molding process (except for the linear actuators in most instances). 
     The resulting structure in FIG. 16 for joint or manipulator 10 can be used to position manipulable support 32 therein anywhere over a wide angular range by forcing pivoting links 20 or 20&#39; to selected rotational positions about the corresponding portion of base support 12 to which they are rotatably coupled by &#34;living hinges&#34; 22 and 22&#39;, respectively. The performance of such a joint or manipulator 10 can be made quite repeatable if the structural members, especially the &#34;living hinges&#34; used therein, are carefully made with materials exhibiting the same properties from batch to batch as well as carefully maintaining essentially identical dimensions from batch to batch in each unit made such as by use of precise laser cutting techniques. In addition, joint or manipulator 10 can be made exceeding small by using these methods, such as cutting the halves and forming the living hinges all by the use of lasers. 
     In addition, such a joint or manipulator can be formed using alternative numbers of pivoting links in the upper and lower pluralities thereof, along with corresponding numbers of pivot holder members, as has been shown in previous examples where such pluralities have included alternative uses of both three and four links as described in FIGS. 1 through 16. The possible number of pivoting arms in each of the upper and lower pluralities, however, is not limited to these alternative numbers shown in the examples previously given. This is demonstrated by a further example shown in FIG. 17 where, arbitrarily, eight pivoting links are used in each of the upper and lower pluralities thereof. Base support 12 and manipulable support 32 are indicated in this structural arrangement for joint or manipulator 10 in FIG. 17, but separate designations are not provided for all eight pivoting links in each of the upper and lower pluralities thereof nor for the eight pivot holder members in view of the clear correspondence with the previous examples. 
     As indicated above, pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34; (or just 25, 25&#39;, 25&#34; in the situation of three links in the upper and lower pluralities thereof) remain in common planes during motions of manipulable support 32 in at least many configurations of joint or manipulator 10. Furthermore, in many of these configurations, these pivot holder members are also essentially only on a certain circle in the common planes which is of a substantially constant diameter. Because of these characteristics, these pivot holder members can be linked to one another to some degree as opposed to being free of any direct interconnections therebetween as seen in the examples described above in connection with FIGS. 1 through 17. Thus, FIG. 18 shows just a lower half of a joint of manipulator 10 as described above and shown in various configurations in FIGS. 1 through 12. Here, however, four pivot holder members, 45, 45&#39;, 45&#34; and 45&#39;&#34;, of somewhat different configuration compared to those in previous examples are provided, the difference being in the presence of a tab extending from the outside thereof away from the side of the member having pivoting links rotatably coupled thereto. These tabs extend outward along the midpoint common plane of pivot holder members 25, 25&#39;, 25&#34; and 25&#39;&#34;. The components shown in reduced manipulator 10&#39; of FIG. 18 have numerical designations there that are the same as those used for components in the structures of FIGS. 1 through 12 of a similar nature. 
     These tabs on these pivot holder members fit into a slot, 46, in a ring, 47, to thereby link the pivot holder members to one another to a degree. The tabs on each of pivot holders 45, 45&#39;, 45&#34; and 45&#39;&#34; can have hardened surfaces to permit the tab to serve as a slider, or can have slider bushings provided thereover, or can have a ball bearing captured on the end thereof for fitting into slot 46. Slot 46 may be provided with a bushing insert or ball bearings to further reduce the friction of the tabs on the pivot holder members moving therein. Provision of ring 46 as shown in FIG. 18 adds both rigidity and strength to the reduced form joint or manipulator, 10&#39;, shown there. 
     The presence of ring 46 allows providing other construction with respect to joint or manipulator 10&#39;, because a platform can be supported across that ring if desired by the user. One such possibility as shown in FIG. 19 where the provision of such a platform, 48, is used to support another such reduced manipulator 10&#39; thereon so as to allow stacking of such reduced manipulators. This presents an alternative way to provide an oriented platform capable of greater angular motion than would be available from a single reduced manipulator 10&#39; by itself. The numerical designations provided in FIG. 18 are not all repeated in FIG. 19, as referring to FIG. 18 makes clear the nature of the components in the stacked manipulators shown in FIG. 19. 
     Such a banding ring arrangement can also be provided, of course, for a full joint or manipulator 10 of the kind described in connection with FIGS. 1 through 15 insofar as providing pivot holder members with tabs extending on the outer sides thereof into the slot of such a surrounding ring to add rigidity and strength. However, because of the presence of the upper plurality of pivoting links 30, 30&#39;, 30&#34; and 30&#39;&#34; along with manipulable support 32 above that ring may interfere with providing a platform supported on the ring, another alternative is shown in FIG. 20. Here, arms, 56, 56&#39;, 56&#34; and 56&#39;&#34;, are affixed in corresponding ones of openings 26, 26&#39;, 26&#34; and 26&#39;&#34; in corresponding pivot holder member 25, 25&#39;, 25&#34; and 25&#39;&#34;. The opposite ends of arms 56, 56&#39;, 56&#34; and 56&#39;&#34; each fit into a slot, 57, in an interior platform, 58. Support arms 56, 56&#39;, 56&#34; and 56&#39;&#34; are affixed in the corresponding ones of the pivot holder members so as to bisect the angle between the rotation axis of the two pivoting links rotatably coupled to each of those members in supporting platform 58, i.e. extend along the common midpoint plane. Platform 58 in this joint interior location is available to, for instance, support additional mechanical instruments operating through opening 31 in manipulable support 32, or to support electronics or optic systems operating through that same opening in support 32. 
     Alternatively, support arms 56, 56&#39;, 56&#34; and 56&#39;&#34; can have the interior ends thereof formed as truncated cylindrical shell with these arms being of sufficient length, and of sufficient separation from the common plane in some instances, to allow them to be stacked over one another such that the axis of radial symmetry of each is aligned with the others. A rod, a pin, through the central opening of each such arm shell will hold them together along a common axis to again provide added strength and rigidity to the manipulator. Also, bearings or bushings may be provided between the shells and the pin to reduce friction. 
     Joint or manipulator 10 as shown in FIGS. 1 through 15 can also be repeated in a stacked fashion in much the same manner as reduced joint or manipulator 10&#39; of FIG. 18 was stacked in FIG. 19. Thus, in FIG. 21, one such joint or manipulator 10 is operably stacked upon another. In so doing, manipulable support 32 of the lower manipulator is combined with the base support of the upper manipulator through forming a common cylindrical shell that is designated 32, 12&#39;, there being an opening extending through this shell designated 31, 13&#39;. A lower sector gear, 65, is affixed to pivoting link 30&#39; of the lower manipulator by pin or pivot screw 29&#39;, and another lower sector gear, 66, is affixed to pivoting link 30 by pin or pivot screw 29. Similarly, a pair of upper sector gears, 65&#39; and 66&#39;, are affixed to two of the pivoting links in the lower plurality thereof for the upper manipulator, and each is engaged with a corresponding one of lower sector gears 65 and 66. 
     Thus, rotation of pivoting links 30 and 30&#39; of the lower manipulator in response to force imparting means rotating pivoting links in the lower plurality thereof in that manipulator will result in rotation of lower sector gear 65 and 66, respectively, and so of upper sector gears 65&#39; and 66&#39;, respectively, along with the lower plurality pivoting arms of the upper manipulator to which they are affixed. Such rotation will result in forcing the output structure, 32&#39; of the upper manipulator in FIG. 21 to correspondingly move. Most of the components in the upper manipulator are not given numerical designations here as their nature can be easily derived from considering a similar component in the lower manipulator in FIG. 21 and consulting the description of similar components in connection with the manipulators of FIGS. 1 through 12. 
     A further change in the system shown in FIG. 21 as compared with the similar manipulators shown in FIGS. 1 through 12 is the substitution of linear actuators for the directly and indirectly connected electric motors used in the examples of FIGS. 1 through 12. These linear actuators are rotatably coupled at one end thereof to mounting arrangement 11 and at the other end thereof to a corresponding one of the pivoting links in the lower plurality thereof in the lower manipulator of FIG. 21. Two of these linear actuators have been labeled 15&#39;&#34; and 16&#39;&#34; in accord with the use of two linear actuators carrying those designations in the system of FIG. 16. Here, however, two further linear actuators are also used to operate the two remaining pivoting links in the lower plurality thereof in this lower manipulator. These two other linear actuators have been designated 35&#39; and 35&#34; in accord with the designation of 35 for the added motor actuator used in connection of the system of FIG. 13. 
     A variation is shown in FIG. 22 in the use of linear actuators in connection with the examples of joint or manipulator 10 in FIGS. 1 through 12. The main mounting arrangement base, 11&#39;, supports a hollow support shaft, 11&#34;, extending upward therefrom to base support 12 of manipulator 10, but this shaft is divided into two sections by a slotted ball, 11&#39;&#34;, with the two sections affixed to opposite sides of this slotted ball to extend vertically to support 12. These two sections also extend more or less perpendicularly to a second generally transverse shaft, 71, extending through a slot, 72, in ball 11&#39;&#34; past the ball outer surface with slot 72 opening generally along the direction of shaft 71. Shaft 71 can rotate back and forth in slot 72 about a pin affixed in ball 11&#39;&#34; extending through a midpoint diameter of this shaft that is oriented perpendicular to the extent of support shaft 11&#34;. The portions of each end of shaft 71 extending past the ball outer surface are supported above a bearing interface, 73, by being inserted in bearings in openings in the upper half of a ring, 74, so as to be rotatably coupled to this upper half. Typically, the upper half of ring 74 is supported by the lower half thereof and the upper half thereof can rotate on bearings at interface 73 with respect to the lower half. A passageway in slotted ball 11&#39;&#34; bypassing slot 72 and meeting each section of shaft 11&#34; would allow a complete passageway from mounting arrangement base 11&#39; to opening 13 in base support 12. 
     Each of pivoting links 20, 20&#39;, 20&#34; and 20&#39;&#34; in the lower plurality thereof have a socket, 75, connected thereto. The top surface of ring 74 also has corresponding sockets, 76, connected thereto. Connecting rods, 77, with a ball at each end thereof extend between a corresponding one of sockets 76 on the surface of ring 74 and a socket 75 connected to a corresponding one of the pivoting links in the lower plurality thereof in manipulator 10, the balls on each end of each rod being fitted into the corresponding sockets. Thus, tilting the upper surface of ring 74 leads to pushing and pulling on pivoting link 20, 20&#39;, 20&#34; and 20&#39;&#34; in the lower plurality thereof so as to result in altering the position of manipulable support 32 as desired. 
     This tilting of the upper surface of ring 74 can be accomplished by tilting ring 74 back and forth about transverse shaft 71 rotatably coupled thereto, and by tilting ring 74 and transverse shaft 71 back and forth about the shaft midpoint pin, all through the extension and retraction of the output shafts of linear actuators 15&#39;&#34; and 16&#39;&#34; which are rotatably coupled to mounting arrangement main base 11&#39;. The output shafts of linear actuators 15&#39;&#34; and 16&#39;&#34; each have a socket, 78, connected thereto and corresponding sockets are connected to the bottom surface of ring 74 but are unseen in the view of FIG. 22. Connecting rods, 79, with a ball on each end thereof extend between the corresponding socket on the output shaft of each of the linear actuators and the corresponding sockets on the bottom surface of ring 74 with the end balls fitted into the corresponding sockets. Thus, extending and retracting the shafts of linear actuators 15&#39;&#34; and 16&#39;&#34; can tilt plate 74 in a direction desired to result in change in the position of manipulable support 32 in manipulator 10 as desired by the user. 
     In addition, shaft 11&#34; can be rotated within mounting arrangement main base 11&#39; to thereby rotate manipulator 10 without any rotation being required of linear actuators 15&#39;&#34; and 16&#39;&#34;, or of main base 11&#39; through the corresponding rotation of ball 11&#39;&#34; and the upper half of ring 74. Thus, roll motion of manipulator 10 is decoupled from the tilting forces provided by actuators 15&#39;&#34; and 16&#39;&#34; for positioning manipulable support 32. 
     A further possibility for providing manipulating forces to joint or manipulator 10 for positioning selected parts thereof is shown in FIG. 23. Here, entirely omitted are the electric motors and linear actuators used in previous examples to manipulate pivoting links in the lower plurality thereof in which they were supported directly by mounting arrangement 11, perhaps while extending through that mounting arrangement. Rather, two electric motors, 15 iv  and 16 iv , are each mounted on a corresponding one of a pair of modified pivot holders, 85 and 85&#39;, present in manipulator 10 in place of corresponding pivot holders 25 and 25&#39;. The other components shown in FIG. 23 have the same numerical designations as components of the same nature shown in the examples of FIGS. 1 through 12. 
     A fragmentary view of electric motor 16 iv  and pivot holder member 85 along with portions of pivoting links 20 and 30 is shown in FIG. 24 with a portion thereof shown in cross section. As can be seen there, the rotor shaft of motor 16 iv  serves as an alternative to pin or pivot screw 27 in extending from the rotor of the motor through pivot hole member 85 and a set of bearings, 86, contained therein to be affixed to pivoting link 30, this rotor shaft and pin being redesignated 87 in FIG. 24. Thus, rather than pivoting link 30 rotating about a pin 27 extending from pivot holding member 25 as before, motor 16 iv  directs the rotation of pivoting link 30 with respect to pivot member 85 through the degree of rotation of its rotor. Pivot holder member 85 is assembled to motor 16 iv  by a pair of screws, 88. Pin 24 is affixed in pivot holder member 85 just as it was affixed in pivot holder member 25 in the examples shown in FIGS. 1 through 12. Pivoting link 20 for the lower plurality thereof can rotate about pin 24 on a further set of bearings, 89, shown in dash line form in FIG. 24. 
     Rotation of rotor shaft 87 of electric motor 16 iv  will result in forcing manipulable support 32 to rotate initially about the base rotational center of rotational motion in base support 12 thereby rotating the combination of pivot holder member 85&#39; and the ends of pivoting links 20&#39; and 30&#39; rotatably coupled thereto along with the combination of pivot holder member 25&#39;&#34; and the ends of pivoting links 20&#39;&#34; and 30&#39;&#34; rotatably coupled thereto. Generally, rotation of the rotor of motor 15 iv  results in the rotation of the combination of pivot holder member 85 along with the ends of pivoting links 20 and 30 rotatably coupled thereto and the combination of pivot holder member 25&#34; and the ends of pivoting links 22&#34; and 30&#34; rotatably coupled thereto. Such rotations can, by causing the rotors of motors 15 iv  and 16 iv  singly or jointly to rotate, result in providing essentially all of the motions for manipulable support 32 that could be provided therefor in the examples shown in FIGS. 1 through 12. 
     A further variation of the system shown in FIG. 23 is to change joint or manipulator 10 from being supported through having base support 12 supported on mounting arrangement 11 to the alternative shown in FIG. 25 where it is supported through a pivoting holder member. This is accomplished by providing a further modified pivot holder member, 85&#39;&#34;, to replace pivot holder member 25&#39;&#34; with this modified pivot holder member having a provision therein allowing it to be mounted on a shaft 11&#34; supported on a main mounting arrangement plate 11&#39;. A modified base support, 12&#34;, rather than being directly supported by mounting arrangement 11 as before, is supported in FIG. 25 by the remaining portions of the structure of manipulator 10 mounted on shaft 11&#39; to thereby allow base support 12&#34; to become the output structure for the system. That is, rotation of the rotors of motors 15 iv  and 16 iv , along with the rotation of mounting plate 11&#39;, allows a further output device, 12&#39;&#34;, mounted on support 12&#34; to be placed anywhere over an area surrounding mounting arrangement plate 11&#39; and to have device 12&#39;&#34; presented at any of a wide range of angles at such a selected position. Manipulable support 32 is allowed to take whatever reactive position occurs in accommodating the placement of device 12&#39;&#34; as desired. 
     A further variant of the system shown in FIG. 23 involving applying motive force at the pivot holder members therein using a different kind of actuator as is shown in FIG. 26. There, linear actuators, 90, 91, 92 and 93, are each directly rotatably connected to and between adjacent pivot holder members, 95, 95&#39;, 95&#34; and 95&#39;&#34;. Although the minimum irreducible length of linear actuators 90, 91, 92 and 93 limits the amount of travel of two adjacent pivot holder members toward one another and so the angular range over which manipulable support 32 can be directed by these actuators, a small but precisely selectable angular range of motion is available to that support under the directions of these linear actuators. 
     This limited range of angular motion for manipulable support 32 can be increased by resort to another variation involving four linear actuators, but with one end of each rotatably mounted to base 11. The other end thereof can be connected through a capturing pulley connected to a corresponding one of a set of four cables each rotatably connected between adjacent pivot holder member pairs. This arrangement allows these linear actuators to again position manipulable support 32 over an angular range therefor by selectively pulling and releasing the corresponding pulley to which it is connected in concert with the others. 
     Although the various versions of the joint or manipulator 10 and 10&#39; described heretofore are all described as being operated by motive means or actuators, either rotational or linear, such a joint can also be used in relatively static situations. A typical use would be as a positionable support for a camera on a tripod, a representation of such an arrangement being provided in FIG. 27. Mounting arrangement 11 is provided as the three-legged tripod base supporting base support 12. 
     Joint 10, rather than having motors 15 and 16 connected to two of the pivoting links in the lower plurality thereof as in the examples of FIGS. 1 through 12, has instead a pair of handles, 96 and 97, fitted on round shafts with portions of these shafts, on the ends thereof opposite the handles, having threads therealong and diameters small enough to pass through holes in pivoting links 20 and 20&#39; into threaded holes (where pins or pivot screws 22 and 22&#39; were) in base support 12. At a length inward from these ends of these shafts equal to the thickness of these links at such holes therein plus a suitable fraction of the depths of the threaded holes in base support 12 a shoulder occurs beyond which the shaft has a greater diameter than the diameters of the holes in these pivoting links. Thus, the pivoting links can rotate about the smaller diameter portions of the shafts until the corresponding handle is sufficiently tightened manually to result in the shoulder on the shaft forcing the corresponding pivoting link against base support 12 to in effect lock it in whatever position it may be at the time of such tightening. By so capturing two of the pivot links in the lower plurality thereof by manually tightening handles 96 and 97 at some corresponding selected angles of rotation of these links about the handle shafts, manipulable support 32 can be fixedly positioned temporarily pointing in any direction over a wide range of angles to direct a camera mounted on manipulable support 32 toward the scene desired to be photographed. 
     In a further possible variation, the pivoting links and pivot holder members, and the base and manipulable supports, used in the various examples of joint or manipulator 10 in FIGS. 1 through 12 for instance, lend themselves to serving as conduits for fluid or light or the like. FIG. 28A is a fragmented elevation view partly in cross section of parts of a portion of a joint or manipulator 10 from the example in FIGS. 6 through 8 showing how a conduit path for fluids can be formed in these parts to permit passing of fluid from mounting arrangement 11 through base support 12, pivoting link 20&#39;, pivot holder member 25&#39;, pivoting link 30&#39; and manipulator support 32. FIG. 28B is a corresponding a top view in cross section of pivot holder 25&#39;, pivoting link 30&#39; and manipulator support 32 of part of the structure shown in FIG. 28A to show part of this same conduit path in these members. Note that pivoting links 20&#39; and 30&#39; rotate about sealed bushings, 98, having an open passageway therethrough, where they are rotatably coupled to base support 12, pivot holder member 25&#39; and manipulable support 32. 
     FIG. 29A shows the same fragmented elevation view, again partly in cross section, of the same conduit path through the same parts of the same manipulator portion as was shown in FIG. 28A but with the path made suitable for transferring a beam of light therealong rather than a fluid. This is accommodated by providing suitable mirrors, 99, at each point in which the light needs to change direction to be kept following the desired conduit path. FIG. 29B provides a top view in cross section of this same light path involving the same structures as were shown in FIG. 28B . 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.