Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
  • B25J18/00—Arms
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
  • B25J9/00—Programme-controlled manipulators
  • B25J9/10—Programme-controlled manipulators characterised by positioning means for manipulator elements
  • B25J9/106—Programme-controlled manipulators characterised by positioning means for manipulator elements with articulated links
  • B25J9/1065—Programme-controlled manipulators characterised by positioning means for manipulator elements with articulated links with parallelograms
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
  • B25J17/00—Joints
  • B25J17/02—Wrist joints
  • B25J17/0258—Two-dimensional joints
  • B25J17/0266—Two-dimensional joints comprising more than two actuating or connecting rods
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S901/00—Robots
  • Y10S901/14—Arm movement, spatial
  • Y10S901/15—Jointed arm
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T74/00—Machine element or mechanism
  • Y10T74/20—Control lever and linkage systems
  • Y10T74/20207—Multiple controlling elements for single controlled element
  • Y10T74/20305—Robotic arm
  • Y10T74/20329—Joint between elements

Definitions

• Parallel robot with two degrees of freedom presenting two kinematic chains whose stiffness in bending is maximized.
• the field of the invention is that of the design and manufacture of manipulator robots. More specifically, the invention relates to a parallel robot with two degrees of freedom of translation, designed for applications involving the placement of components or objects at high speed, these applications being commonly referred to as "pick and place” .
• Robots used for high-speed handling applications are few. Robots of this type can however be classified into two main categories:
• serial robots composed of a succession of rigid elements and motorized joints, thus forming an open kinematic chain, the driven member being connected to the base by a single kinematic chain;
• parallel robots composed of at least two kinematic chains, connecting the base to the driven member, commonly referred to as the "platform", thus forming a closed architecture.
• Each category can be further broken down into sub categories based on the robot's number of degrees of freedom.
• These robots have four degrees of freedom: 3 translations and 1 rotation of the controlled organ.
• parallel architecture robots have the advantage of minimizing moving masses, especially when the motors are fixed on the base, which improves the dynamic performance.
• closed architectures intrinsically generate a greater stiffness of the kinematic chains implemented.
• Robots of this type have greater acceleration capabilities (ranging from 15 G to 25 G) than serial robots, with Adept cycle times ranging from 0.25 s to 0.33 s.
• robots are useful in many tasks, such as handling operations between two conveyors or assembly components.
• robots space-architecture robots, whose movements of certain elements take place in non-parallel planes.
• the most commonly used robots are planar robots.
• we know robots such as those illustrated in Figures 1 and 2, the constant orientation of the platform is maintained through the use of planar parallelograms, which allow only translations between solids. They can be either driven by rotary motors, or in some cases by linear motors.
• this achieves cycle times of 1.7 s, accelerations of 18 G and a repeatability of 0.5 mm. Its acceleration capabilities are limited because of the planar architecture which has a lower stiffness since it is subjected to bending stresses in the direction normal to the plane of displacement.
• This robot described by the patent document published under the number WO-2009/089916, has the particularity of having a kinematic spatial chain, that is to say that, although the movements of the platform remain in a plane , the movements of some other elements constituting the kinematic chains may not be made in this plane.
• the robot consists of four legs connecting the fixed base to the mobile platform, each leg consisting of an arm and a spatial parallelogram consisting of two bars connected at their ends to the platform and the arm by ball joints.
• the architecture of this robot is designed in such a way that many bending stresses are removed, improving the stiffness of the robot and thus reducing the masses in motion.
• Such a robot achieves accelerations greater than 50 G, Adept cycle times of 0.25 s.
• the architecture of the robot is complex (with its four legs), tending to increase the difficulty of identification models used to control the robot, which can therefore be imprecise and, therefore, deteriorate the final accuracy of the robot;
• the invention particularly aims to overcome the disadvantages of the prior art.
• the object of the invention is to propose a parallel robot with two degrees of freedom of translation with a maximized flexural stiffness which makes it possible to improve the acceleration capacities, and therefore the speeds, of the robot and / or get better final precision.
• the invention also aims to reduce the complexity of the architecture compared to some robots of the prior art.
• Another object of the invention is to provide such a robot which limits the maintenance operations.
• a parallel robot composed of two kinematic chains connecting a base to a platform intended to be displaced with respect to the base , of the type having only two degrees of freedom so that the platform is movable relative to the base in a plane (x, z) of a space (x, y, z) in which the directions x, y and z are orthogonal to each other, the kinematic chains each having an elbow connecting a proximal sub-chain, itself connected to the base, and a distal substring, itself connected to the platform, said proximal sub-chain being intended to drive the bend in translation in the plane (x , z).
• the distal substring of at least one of the two kinematic chains comprises two bars spaced from each other in the direction (y), a first end of each bar being connected to said elbow by a linking system composed of two axes pivots orthogonal to each other, the axes of the two pivots of the connection system of one of the bars each forming a non-zero angle with the axes of the two pivots of the connection system of the other bar, the second end of each bar being connected to said platform by a connection system also composed of two axis pivots orthogonal to each other, the axes of the two pivots of the connection system of one of the bars each forming a non-zero angle with the axes of the two pivots of the connection system of the other bar.
• the connecting systems connecting the bars of the distal substring on the one hand to the elbow and, on the other hand, to the platform allow to work the bars of the distal substring only in tension and / or in compression and / or in torsion.
• all the bending stresses are reported at the level of the proximal sub-chain, which is an element of which robot designers classically manage to adapt the characteristics to withstand bending stresses without significantly impairing accuracy and / or or the pace of the robot.
• a robot according to the invention comprises many fewer elements subjected to these bending stresses.
• it is inherently steeper than existing planar robots. This makes it possible to lighten the mass of the moving elements and to improve the acceleration capabilities and / or its accuracy.
• the architecture according to the invention is at least twice as light as a robot such as that illustrated in FIG.
• a robot according to the invention has a space of bigger work and fewer moving masses.
• the architecture of a robot according to the invention is about one and a half times lighter than the robot described by the document WO-2009/089916.
• the improvement of the stiffness and the reduction of the moving masses of a robot according to the invention makes it possible to lead to an improvement in its acceleration capabilities and to an improvement in its accuracy with respect to the robot of the invention.
• prior art the working space (area swept by the mobile platform in the Cartesian space) is larger with a robot according to the invention.
• the architecture of a robot according to the invention only implements two kinematic chains, and does not implement ball joints. On the contrary, all these connections can be made using bearings, which are by default well suited to high speed movements in the mechanisms. It results from these advantages, a reduction of maintenance operations and ease of control of the robot to obtain a very good accuracy.
• the two pivots connecting said bar to the elbows are grouped together in a gimbal for at least one of the bars.
• the two pivots connecting said bar to the platform are grouped together in a gimbal for at least one of the bars.
• the implementation of one and / or the other of these characteristics makes it possible to obtain a robot of greater compactness.
• the axes of the two pivots at one end of the bar are parallel to the axes of the pivots at the other end of the bar.
• the proximal substring comprises two parallel sides defining with the base and the elbow a parallelogram.
• each side is advantageously connected to the base by a pivot.
• each kinematic chain is connected to the base by at least one motorized pivot.
• each side is advantageously connected to the bend also by a pivot.
• the pivots that connect the two sides to the base and the elbow are all parallel to each other.
• At least one of the sides comprises two parallel rods.
• the proximal substring comprises a set of three links linking the base to the elbow, a first of which is connected at each of its ends by two pivots and the other two of which are each connected on the one hand to the base by a connection system composed of two axes pivots orthogonal to each other and, on the other hand, to the elbow also by a connection system composed of two axes pivots orthogonal to each other.
• the proximal substring comprises two segments interconnected by a prismatic connection, one of the segments being connected to the base and the other segment being connected to the platform.
• Figures 1 and 2 are robots of the prior art
• FIG. 3 is a schematic perspective view of a robot according to a first embodiment of the invention
• Figures 4 and 5 are diagrams illustrating the numbering rules of the directions Xkji, ykji and ⁇ ;
• Figure 6 is a partial kinematic representation of the robot illustrated in Figure 3;
• FIG. 7 is a partial kinematic representation of a robot according to a second embodiment of the invention
• FIG. 8 is a partial kinematic representation of a robot according to a third embodiment of the invention
• Fig. 9 is a partial kinematic representation of a robot and a fourth embodiment of the invention
• FIG. 10 is a partial kinematic representation of a robot according to a fifth embodiment of the invention.
• a parallel robot according to the invention comprises two kinematic chains 1, 2, each connecting the base 3 to the platform 4 (constituting the driven mobile member), intended to be displaced with respect to the base (constituting the fixed organ).
• Such a robot has only two degrees of freedom of translation so that the platform 4 can be moved relative to the base in a plane x 0 , z 0 of a space (xo, yo, z 0 ) in which the directions xo, yo and z 0 are orthogonal to each other and define a three-dimensional space.
• Each cinematic chain (where both s are identical) comprises:
• the elbow 1 1 connects, by a system of connections described in more detail later, the proximal substring and the distal substring.
• the proximal substring is connected by one of its ends to the elbow 1 1, and the other of its ends to the base 3, this via pivot type links.
• the distal substring is connected on the one hand to the elbow 11, and on the other hand to the platform by a connection system also described in more detail later.
• the distal substring of the two kinematic chains of the robot comprises two bars 120, 121 spaced apart from each other in the y direction.
• the bars 120, 121 are not parallel to each other and extend symmetrically with respect to a median axis connecting the bend 11 and the platform 4 between the lower and upper ends of the bars. 120, 121.
• joints between the bars of the distal substring and the elbow on the one hand, and the platform on the other hand are designed so that:
• the end of the upper bar 120 is connected to the bend 11 by a connecting system composed of two axes pivots orthogonal to each other;
• the upper end of the bar 121 is connected to the bend 11 by a connecting system composed of two axes pivots orthogonal to each other;
• the lower end of the bar 120 is connected to the platform 4 by a connecting system also composed of two axes pivots orthogonal to each other; the lower end of the bar 121 is connected to the platform 4 by a connecting system also composed of two axes of pins orthogonal to each other.
• the axes of the two pivots of the connecting system connecting the upper end of the bar 120 with the elbow 11 each form a non-zero angle with the axes of the two pivots of the connecting system connecting the upper end of the bar 121 with the elbow 11.
• connection systems of the lower ends of the bars 120, 121 More specifically, the axes of the two pivots of the connection system connecting the lower end of the bar 120 with the platform 4 each form a non-zero angle with the axes of the two pivots of the connecting system connecting the lower end of the bar 121 with the platform.
• the axes of the two pivots of the connecting system at one end of the bar are parallel to the axes of the two pivots of the connecting system at the other end of the bar.
• FIG. 6 kinematically represents one of the kinematic chains of a robot according to a first embodiment of the invention.
• the distal substring is designed as follows:
• the bar 120 is connected to the bend 1 1 by a set of two pivots 50, 5 1, the pivot 51 having a pivot axis yni and the pivot 50 having a pivot axis z 2 n orthogonal to the pivot axis ym;
• the bar 120 is connected to the platform 4 by two pivots 52, 53, the pivot 52 having a pivot axis ym (therefore parallel to that of the pivot axis of the pivot 5 1) and the pivot 53 having an axis pivoting z 2 n (so parallel to the pivot axis of the pivot 50) orthogonal to the pivot axis ym;
• the bar 121 is connected to the bend 1 1 by two pivots 60, 61, the pivot 61 having a pivot axis ym and the pivot 60 having a pivot axis Z221 orthogonal to the pivot axis ym;
• the bar 121 is connected to the platform 4 by two pivots 62, 63, the pivot 62 having a pivot axis ym (thus parallel to the axis of the pivot 61) and the pivot 63 having a pivot axis z 2 2i (therefore parallel to the axis of the pivot 60).
• the pivot axes ym and ym respectively of the pivots 51 and 61 are neither parallel nor merged. It is the same for the pivot axes yi n and y m respectively pivots 52 and 62.
• the proximal sub-chain 10 is constituted by two parallel sides 101, 102, defining a parallelogram with the base 3 and with the bend 11.
• the upper ends of the bars 101, 102 are connected to the base 3 each by a pivot connection 70, 71.
• the pivots 70, 71 have pivot axes parallel to each other, in the direction y 0 of the reference 3 ⁇ 4, y 0 , z 0 associated with the base 3.
• the lower ends of the bars 101, 102 are connected to the bend 11 each by a pivot 72, 73.
• the pivots 72, 73 have pivot axes parallel to each other extending in the direction yo.
• the axes of the pivots 70, 71 are therefore parallel to each other and parallel to the pivot axes of the pivots 72, 73.
• the robot furthermore has the following characteristics:
• the bars 120, 121 are non-parallel, and extend symmetrically on either side of a median axis connecting the points 123, 124 (the point 123 being the point centered between the lower ends of the bars 120, 121 at the level of platform 4 and the point 124 being the point centered between the upper ends of the bars 120, 121 at the elbow 1 1);
• the base 3 is part of a plane P 0 defined by the direction x 0 , yo of a reference xo, zo associated with the base, the platform 4 s' registering in a plane P2 parallel to the plane Po;
• the bend 11 is in a plane Pi, parallel to the plane P 0 , in which the directions ym and ym are inscribed.
• one of the pivots 70, 71 respectively connecting the bars 101, 102 to the base 3 is actuated by a motor fixed on the base 3.
• Figure 7 illustrates a second embodiment of the invention.
• pivots 50, 51 of the connecting system connecting the bar 120 to the elbow 1 1 are grouped within a universal joint 54 whose pivot axes are orthogonal and take the directions of yni and z 2 u pivots 50, 51;
• pivots 52, 53 of the connecting system connecting the leg 120 to the platform 4 are grouped in a universal joint 55 whose orthogonal axes take the directions ym and z 2 n pivots 52, 53;
• the pivots 60, 61 of the connecting system connecting the bar 121 to the elbow 1 1 are grouped together in a cardan shaft 64 whose orthogonal axes take the direction yi 2 i and z 2 2i of the pivots 61,
• the pivots 62, 63 of the connecting system connecting the bar 121 to the platform 4 are grouped in a universal joint 65 whose orthogonal axes take the directions ym and z 22 i pivots 62, 63.
• FIG. 8 illustrates, in kinematic form, a variant of the kinematic chain illustrated in FIG. 7. According to the variant illustrated in FIG. 8, the connection systems connecting the bars 120, 121 to the bend 11 and to the platform 4 are retained.
• the parallelogram of the proximal substring 10 is replaced by two segments 103, 104 interconnected by a prismatic connection 105, the segment 103 being connected to the base 3 and the segment 104 being connected to the elbow 11.
• the proximal substring has been modified in order to improve its stiffness in flexion, without, however, changing the movement of the elbow (translation relative to the base).
• one of the sub-assemblies of the parallelogram formed by the proximal substring 10 has been doubled in order to improve its bending stiffness.
• the proximal substring 10 thus consists of two subassemblies forming two parallel sides of a parallelogram, namely:
• a first subassembly constituted by a bead 101
• a second subassembly consisting of two rods 1020 and 1021 parallel to each other.
• first subassembly therefore define a parallelogram with the base 3 and the bend 1 1. It should be noted that the first subassembly could also consist of two rods parallel to each other according to another alternative.
• the parallelogram of the proximal substring is deleted and replaced by a set of three bars.
• the bar number 106 is the actuated bar of the system, therefore the one that is connected to the motor placed on the base. It is connected to the elbow by a pivot axis y 0 .
• the base is also connected to the elbow by the bars 107, 108 via cardan links (or orthogonal pivots), respectively 1070 and 1080 fixed at their ends.
• the axes of the two gimbals 1070, 1071 of the bar 107 are parallel to each other.
• the y and y axes 14 must not be parallel to each other.
• This type of system allows a circular translation of the elbow. Its main advantage is as follows: bars 107 and 108, thanks to the arrangement particular cardan links, are solicited only in traction / compression / torsion. Thus, the stiffness of the proximal portion is greatly increased by this system. It should however be noted that the bar 106 is always biased in bending, this stress being minimized by the use of the mechanism composed of bars 107 and 108.

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• Engineering & Computer Science (AREA)
• Robotics (AREA)
• Mechanical Engineering (AREA)
• Transmission Devices (AREA)
• Manipulator (AREA)

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• 2010
  • 2010-11-22 FR FR1004525A patent/FR2967603B1/fr not_active Expired - Fee Related
• 2011
  • 2011-11-21 JP JP2013540316A patent/JP5871943B2/ja not_active Expired - Fee Related
  • 2011-11-21 US US13/989,002 patent/US20140020500A1/en not_active Abandoned
  • 2011-11-21 EP EP11785671.6A patent/EP2643127A1/de not_active Withdrawn
  • 2011-11-21 WO PCT/EP2011/070598 patent/WO2012069430A1/fr active Application Filing

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