FR2559283A1 - Articulation for a manipulator used for programming or control of a robot and articulated manipulator - Google Patents

Abstract

Articulation for a manipulator used for programming or control of a robot and articulated manipulator. A hollow body 14 contains a shaft 18 around which are mounted a rotation elastic return means 23 acting on two opposed flats 18A, a piston 20 activating this elastic return means 23 at will, a second piston 35 pushed by a spring 39 in order to clamp or free a disc 19 which is fixed to the shaft 18 with respect to an internal partition 31 in such a way that this articulation can have three separate states: free, locked, elastically returned to any locked position.

Description

 The subject of the invention is a joint which can be used for making the joints of the trunk, shoulder, elbow, wrist on a manipulator used to program or to control a robot having motorized joints in equal number.

 More precisely, the articulation of the invention is well suited to the production of a portable articulated manipulator, of reduced dimensions, usable as a master for direct control or programming by learning of one or more robots, or of a robot arm or wrist robot slaves.

 The invention also relates to a master manipulator provided with one or more articulations according to the invention.

Programming by learning robots is widely used in industry. Despite the existence and continuous development of symbolic languages for controlling robots, the advantage of the learning method is certain, either that it is only available for machines intended for the execution of simple tasks, or that it be used in addition to a main command by language. The ease of use and the performance of the learning method depend directly on the manual control used. We know the command by manipulator known as "button box", very widespread, but not very convenient, and the command by manipulator of the syntax type, much more effective in particular for the execution of continuous trajectories. articulated mechanics, operated by the operator, realizing a transposition between his own movements and those of the robot via a mechanical, electronic or computerized coordinate changer. We thus know handle type syntaxers,
puppet, or robot master.

 The articulation of the invention applies to the realization of a syntax of robot-maltre type, portable and of low cost, with coordinate changer of computer type, very effective because allowing a gestural command whose execution is turns out to be particularly natural.

 A coupling between a master organ and a slave organ has a much greater flexibility when it is possible to achieve at will either a so-called position positioning (P / P) coupling thanks to which the slave organ takes the same positions-as the marten organ , or a so-called position-speed (PV) coupling by which any separation of the master member from any initial position, results in a displacement in the same direction as the slave member at a speed which is a function of l importance of this spacing.

It appeared that a satisfactory operation of the maltre-slave assembly is obtained when the joints can be put in three defined states which are:
- the so-called free state (L) in which the master organ remains in indifferent equilibrium when it is left to itself; this condition requires a good balancing of the constituent parts of this body and a slight residual friction torque.

 This free state is desirable for position-position coupling (P / P).

 - the state called elastic return (RE) to any blocking position in which a return torque, which is preferably adjustable, returns the joint to any initial position after a distance from it of + 15 to 200.

 - the so-called blocking state (B) at any position in which the joint is blocked and no longer works.

 These last two states are desirable for position-speed coupling (P-V).

 The main purpose of the invention is to provide a joint which can be mounted on the trunk, shoulder, elbow or wrist of a master structure and which can be placed at will in any of the three states defined above. above.

A joint according to the invention for joining a first element to a second element comprises a hollow body having transverse internal faces limiting a recess with a longitudinal axis and intended to be fixed to the first element, a shaft supported freely in rotation in this hollow body coaxially with the longitudinal axis to extend in said recess and intended to be fixed to the second element 2 this shaft is provided on the one hand, with a blocking element extending opposite a first race inside of the hollow body, on the other, of an elastic return means in rotation comprising a first part which is applied elastically against 1 shaft and a second extending part. in race with a second inner ace of the hollow body; at least one piston is arranged around the shaft in the recess to slide in leaktight manner in the latter and along the shaft to act, at will, on the locking element or on the elastic return means
According to a first alternative embodiment of the invention, the piston is placed between the blocking element and the elastic return means in rotation, the assembly consisting of the blocking element, the piston and the elastic return means located between two interior faces of the recess, however channels are drilled through the wall of the hollow body to allow the arrival or the evacuation of hydraulic fluid on either side of the piston
According to a second alternative embodiment of the invention, the recess is divided by a partial transverse partition into two communicating volumes, the elastic return means and a first piston are mounted in a first volume, the locking element and a second piston are mounted in a second volume, channels are drilled through the wall of the hollow body to allow the arrival or evacuation of hydraulic fluid for the functional movements of the first and second piston.

 Preferably, the first piston is close to the partial transverse partition on one side thereof, the blocking element is close to the partial transverse partition on the other side thereof, this blocking element is crossed by holes in its part released from the partial transverse partition and the second piston is pushed back by a spring in the direction of the blocking element, the channels drilled through the body being situated so that the fluid under pressure pushes the pistons in them away from the partial transverse bulkhead.

 Advantageously, in one embodiment of the invention, the locking element is a disc transverse to the shaft which is fixed to the shaft or which forms an integral part of it, arranged to be clamped by a piston against an internal face. from the body.

 The elastic return means comprises a cylindrical envelope mounted in the body and having an opening transverse to the shaft, at least one piston mounted sliding in this transverse opening, a spring pressed against a stop at one end of the opening and pushing the piston against the shaft or against a part fixed to the latter; according to a first variant, the end of the piston close to the shaft has an end V-shaped face and a part fixed to the shaft is contained in this V-shaped face; according to a second variant, the shaft has two opposite parallel flats and there are two pistons arranged in opposite directions to each apply against a flat under the thrust of a corresponding spring.

 A master structure, in accordance with the invention, has an end part comprising three articulations in accordance with the first embodiment, and these three articulations are arranged with their concurrent longitudinal axes. Preferably, this structure also comprises, at points similar to an elbow, a shoulder and a trunk, three joints in accordance with the second embodiment of the invention.

The mechanical structure is completed by electronic and computer means which provide two main functions: - allowing dialogue between the operator and the structures
master and slave through a console
order, for example a low cost trade model
having a standard serial link; - ensure transmission to the slave structure and its
means for controlling position information
angularity of each joint and the state of these
(L, RE, B).

We will now give, without limiting intention and without excluding any variant, a description of two embodiments with reference to the accompanying drawings in which:
FIG. 1 is a schematic representation of a master structure with 6 axes of rotation using the articulation of the invention,
FIG. 2 is a view in section through a plane passing through the axis, along II-II of FIG. 3, of a first embodiment of the invention,
FIG. 3 is a sectional view along III-III of FIG. 2,
FIG. 4 is a sectional view through a plane passing through the axis, according to IV-IV of FIG. 5 of a second embodiment of the invention,
FIG. 5 is a sectional view along VV of FIG. 4,
- Figure 6 is a sectional view similar to Figure 5 showing an alternative embodiment of the elastic return means of the invention.

The structure represented in FIG. 1 comprises the two embodiments of the invention, the simplest mode of FIGS. 2 and 3 to form so-called wrist joints designated by the general reference P and the most improved mode of FIGS. 3 and 4 to constitute so-called elbow and trunk joints designated by the general reference C. In this example, there are therefore three wrist joints P at the extreme part of the arm. The most extreme joint
P1 is mounted on a branch 1 of a bracket 2 to 900, the second branch 3 of which carries a second articulation P2.

This is also joined to a branch 4 of a bracket 5 to 900, the second branch 6 of which is joined to the third articulation P3. In this way, the brackets 2 and 5 having their branches located in parallel planes, with their angles arranged in opposition; the axes of rotation of the shafts of the most extreme joint P1, of the second joint P2 and of the third joint P3 are concurrent.

The third joint P3 is joined to a branch 7 of a bracket 8 to 900, the second branch 9 of which is joined in the region of the elbow via the first joint C1 at the end of an arm 10. The latter is articulated in the shoulder region at the top of a trunk 11 via the second articulation
C2. The trunk 11 is itself mounted to rotate on a base 12 thanks to a trunk joint C3.

 The articulations C and P of the invention can be used otherwise on wrists, arms, robots, or manipulators having a different structure and an identical or different number of axes of articulation.

 Reference will now be made more specifically to FIGS. 2 and 3 to describe the simplest embodiment of the invention.

 A hollow body 14 is intended to be fixed to a first element to be articulated, for example a branch of a square 2,5, 8. It has internal faces 15 which limit a recess 16 with a longitudinal geometric axis 17.

A shaft 18 is supported in the hollow body 14 coaxial with the longitudinal geometric axis 17. It projects at one end to be fixed to a second element to be articulated, for example another branch of a bracket 2, 5, 8. This shaft 18 passes through the recess 16 and inside it is provided with a blocking element constituted by a disc 19 fixed in transverse position to the shaft 18 and placed, at least in part, opposite an inner face 15 of the recess 16.

 A piston 20 is inserted into the recess 16, around the shaft 18, pollr being able to slide in a sealed manner in the direction of the geometric axis 17. This piston 20 has a lateral face 20E adjacent to the disc 19 by which it can be applies against the latter in order to immobilize it against the internal face of the body 14. In this situation the articulation is in the blocking state (B) since the shaft 18 is immobilized with respect to the body 14.

 On the side of the opposite face 20 B of the piston 20 is formed in the recess 16. a chamber 21 for supplying pressurized fluid placed in communication with a supply channel 22. This chamber 21 contains an elastic return means in rotation designated by the general reference 23, better visible in FIG. 3. In this example, this elastic return means 23 comprises a cylindrical envelope 24 in which is provided a transverse and diametral opening 25 which contains two pison 26 sliding in the radial direction, on either side of 11 shaft 18. Between these two pistons 26, this shaft 18 is reduced in size inside the casing 24 to present two opposite parallel flats 18A against which the two pistons 26 are applied .The latter are pushed towards the flats 18A by two springs 27, the opposite end of which bears against a stop 28 screwed into the cylindrical casing 24.

 When the cylindrical envelope 24 is left free in the chamber 21, the assembly of the elastic return means rotates with the shaft 18 inside the body 14.

But when this same casing 24 is immobilized with respect to the body 14 while the pistons 26 retain their sliding freedom in the radial direction, the shaft 18 can rotate. The flats 18A are set obliquely to the pistons 26 by pushing the latter against the effect of the springs 27. In this situation, as long as the pistons 26 remain in contact respectively with opposite longitudinal edges of the flats 18A, they exert on the shaft 18 a return torque which tends to return this shaft to its initial position visible in FIG. 3 in which the two pistons are each applied to the entire surface of a flat 18A. The joint is then in the elastic return state (RE).

 The elastic return means 23 is placed in the chamber 21 between an inner face 15 of the body 14 and the face 20B of the piston 20. Another chamber 29 which communicates with a supply channel 30 is provided on the side of the face 20A of this piston 20. The disc 19 is located in this other chamber 29 and it is perforated to be traversed by the pressurized fluid. This pushes the piston 20 which then firmly applies the envelope 24 against the inner surface 15 of the body 14 and immobilizes it. This immobilization takes place at any rotational position of the shaft 18. The two opposite pistons 26 which act on the flats 18A have a fairly small dimension compared to that of the opening 25 in which they are housed so as not to be in contact with the piston 20.

Thus the elastic recall explained above occurs without any hindrance.

 The envelope 24 is also perforated in the direction of the axis 17, like the disc 19 so that it is freely traversed by the pressurized fluid which can be sent into the chamber 21.

 In the absence of pressure in the two chambers 21 and 29, the piston 20 does not immobilize the disc 19 or the casing 24, so that the shaft 18 is free to rotate.

 It will be rotated that in this example of FIGS. 2, 3 of an articulation P, the piston 20 is placed between the blocking element constituted by the disc 19 and the elastic return means 23, inside the recess 16 .

 We will now describe the articulation illustrated by FIGS. 4 and 5. We will use the same numerical references to designate identical or analogous parts having the same functions. We will mainly insist on the differences which exist between these two examples of realization. The hollow body 14 is intended to be fixed, for example, to the second branch 9 of the bracket 8; this body 14 contains the shaft 18 which is intended to be fixed to the arm 10 (FIG. 1). In the recess 16 are mounted, around the shaft 18 and the geometric axis 17, from a face internal 15 of the recess 21, firstly the elastic return means 23, then the piston 20 serving to immobilize the casing 24 of this return means 23, finally the locking element 19 also constituted here by a disc 19 which is an integral part of the tree 18.

 The main difference with the previous example is that the piston 29 only serves to immobilize the envelope 24 of the elastic return means 23, when it is pushed back until it comes into contact by its face 20A with this envelope 24. Between the piston 20 and the disc 19 there is a partial transverse partition 31 which is open at its center to let the shaft pass through. It has internal faces 15 and it divides the recess 16 into two volumes. A first volume contains the elastic return means 23, the piston 20 and a fluid chamber 32 which communicates with a supply channel 33. The second volume contains the disc 19 pierced with holes 19A, a fluid chamber 34 and a second piston 35. of fluid 34 communicates through the holes 19A of the disc 19 and through the central opening of the partition 31 with the fluid chamber 32. In addition, the second piston 35 and the hollow body 14 have, in correspondence, shoulders 36 which limit an annular chamber 37. This communicates as with a second supply channel 38. A return spring 39 is mounted between the second piston 35 and the end wall adjacent to the hollow body 14 to push this second piston 35 towards the disc 19.

 The operation of this joint C is as follows.

 In the absence of pressure in the two chambers 32 and 37, the elastic return means 23 is free and without effect, the second piston 35 is pushed by the spring 39 against the disc 19 which 8 ss 1 clamps against the transverse partition 31 , so that the joint is blocked, at least up to a certain value of the torque which can be determined in advance. The joint is in the locked state (B).

 When fluid under pressure is sent to the chamber 37 alone, the second piston 35 is moved away from the disc 19. The articulation is free and is in the state (L).

 When fluid under pressure is sent to the chamber 32 alone, this fluid also arrives in the chamber 34, through the disc 19 and it acts both on the two pistons 20 and 35 by moving them away from the transverse partition 31. The piston 20 immobilizes the casing 14 of the elastic return means 23 as explained above; the piston 35 is moved away from the disc 19 which it releases. The joint is then in the state of elastic return (RE).

 In short, the essential difference between the two joints C and P is that, in the absence of pressurized fluid, the joint C is blocked by the effect of the spring 39 while the joint P is free.

 In FIG. 4, it can be seen that the shaft 18 is extended outside the casing 14, at its end opposite to that where the arm 10 is located, up to a sensor 40, of potentiometric type for example, which makes it possible to measure the angular position of this tree.

Figure 6 relates to an alternative embodiment of the elastic return means 23 In this variant, the en = Jeloppe 24 mounted inside the hollow body 14 has a transverse opening 25 which contains only a single piston 26 ç the latter is pushed by a spring 27 which bears against a screwed stop 28. The piston 26 has an end free face 26A cut in V. In this face V is contained a longitudinal lug 18B which is part of the shaft 18 and which is eccentric with respect to the geometric axis 17. Any angular displacement of 1 shaft 18 which separates the lug 13B from the plane of symmetry of the face 26A in
V causes an elastic return to its initial position visible in FIG. 6. This occurs when the casing 24 is immobilized in rotation relative to the shaft 18
In an alternative embodiment, the arm 10 is extended beyond its articulation with the trunk II and the articulation C1 is mounted at the end of the extension 10A shown in phantom in FIG. 1.

A toothed belt 1OB transmits the movement of rotation of the elbow axis, that is to say the bracket 8 to which the three wrist joints P1 to P3 are fixed. This arrangement makes it possible to obtain a structure with indifferent equilibrium around the shoulder axis.

Claims (10)

 1. Joint to join a first element to a second element of an articulated structure of the master type, characterized in that it comprises on the one hand, a hollow body (14) having transverse internal faces (15) limiting a recess (16) with longitudinal axis (17), intended to be fixed to the first element; on the other hand, a shaft (18) mounted to rotate freely in this hollow body coaxially with the longitudinal axis (17), intended to be fixed to the second element; this shaft (18) is provided inside the recess (16) with a blocking element (19) placed opposite a first inner face (15), and with an elastic return means in rotation (23) having at least one envelope (24) surrounding the shaft (18), disposed opposite a second inner face (15), with a transverse opening (25) containing at least one piston (26) applied elastically against the shaft (18), however at least one piston (20-) is arranged in the recess (16) around the shaft (18) to tighten, as desired, the locking element (19) or the elastic return means in rotation (23) against the corresponding inner face (15).  2. Joint according to claim 1, characterized in that a single piston (20) is disposed between the locking element (19) and the elastic return means in rotation (23), fluid supply chambers under pressure (21,29) being provided on either side of this piston (20) and respectively containing the locking element (19) and the elastic return means (23).  3. Joint according to claim 1, characterized in that a partial transverse partition (31) with internal faces (15) divides the recess (16) dVune part into a first volume which contains the elastic return means (23), the piston (20), a fluid chamber (32), this piston (20) being close to said partition (31), on the other hand in a second volume which contains the locking element (19) near said partition (31), a fluid chamber (34), a second piston (35), a spring (39) pushing this second piston (35) towards the locking element (19), the hollow body (14) and the second piston (35) having corresponding shoulders (36) which limit an annular fluid chamber (37), the fluid chambers (32, 34) close to the piston (20) and the second piston (35) respectively in communication through the partial transverse partition (31) and through the blocking element (19) pierced with holes (19A).  4. Joint according to any one of claims 1 to 3, characterized in that the locking element is a disc (19) transverse to the longitudinal axis tel7), which is integral with the shaft (18).  5. Joint according to claim 1, characterized in that the shaft (18) has inside the envelope (24) of the elastic return means (23) two flats (18A) parallel, two pistons (26) are mounted in the transverse opening (25) and each pushed by a corresponding spring (27) against a flat (18A).  6. Joint according to claim 1 characterized in that the shaft (18) is provided inside the envelope (24) with a longitudinal lug (1BB) eccentric with respect to the longitudinal axis (17), a single piston (26) is mounted in the transverse opening (25) with a free end face (26A) cut into a V, to contain the longitudinal lug (18B).  7. articulated master structure, characterized in that it is provided at its free end with three articulations, according to claim 2, these three articulations comprising an extreme articulation (P1) followed by an intermediate articulation (P2) and a third articulation (P3), the longitudinal axes of the extreme articulation (P1) of the second articulation (P2) and of the third articulation (P3) being concurrent.  8. Master structure according to claim 7 characterized in that it further comprises, on the one hand between its end part and an arm (10), on the other hand between this arm (10) and a trunk (11) , two joints (C1, C2) according to claim 3.  9. Master structure according to claim 8, characterized in that it further comprises a third articulation (C3) according to claim 3 mounted between the trunk (11) and a nozzle (12) supporting this trunk.  10. Structure according to claim 8, characterized in that the arm (10) has an extension (10A) beyond its articulation with the trunk (11), the articulation (C1) between the end part and this arm (10) is mounted at the end of this extension (10A) and joined by a belt (10B) to the axis of articulation of said end part.