Robot and control method adapted to reorient an object grasped by the robot.

Abstract

A robot comprising an electronic control unit (9) and a hand (8) having a plate (10) carrying a plurality of contact gripping elements (11, 20, 30) connected to the electronic control unit (9), characterized in that the gripping elements (11, 20, 30) are arranged to hold the same object stationary in a coordinate system (x, y, z) of the hand (8) by means of a first gripping configuration and a second gripping configuration distinct from the first gripping configuration, and in that the electronic control unit (9) is arranged to control the gripping elements (11, 20, 30) to grasp the object by activating the first gripping configuration, then activating the second gripping configuration while keeping the first gripping configuration active, and then deactivating the first gripping configuration. (Figure from the abstract: Fig. 2)

Description

Title of the invention: Robot and control method adapted to reorient an object grasped by the robot.

[0001] The present invention relates to the field of robotics and more particularly to that of object grasping.

[0002] BACKGROUND OF THE INVENTION

[0003] A manipulation robot generally comprises a hand including a plate (which, in a human hand, can be likened to the proximal part, palm and back of the hand), a plurality of articulated fingers mounted on the plate, a motorization for moving the fingers and an electronic control unit connected to the motorization and programmed to move the fingers so as to grasp and then release an object.

[0004] Such handling robots are used for example to move parts in production lines.

[0005] The part is presented on a support, and the robot hand is approached to grasp the part, either by wrapping its fingers around a portion of the part (with all the fingers and the hand's mounting plate then in contact with the part) or by pinching the part between the distal ends of two or more fingers. The configuration of the finger interaction zones with the part is fixed and is determined by the hand's position relative to the part at the moment of grasping. It is understood that the fingers may obscure portions of the part that require intervention, for example, for machining, visual inspection, or the application of a coating layer. To modify this configuration of the finger interaction zones with the part, it is necessary to reposition the part, change the hand's orientation relative to the part, and then grasp the part again with this new orientation.Alternatively, the part can be transferred to another robot for the necessary intervention.

[0006] Such an approach leads to an increase in cycle time, thus penalizing the productivity of the manufacturing line, or requires the acquisition of a new robot, increasing the investments to be made for manufacturing.

[0007] SUBJECT OF THE INVENTION

[0008] The invention is intended in particular to remedy at least in part the aforementioned drawbacks. Summary of the invention

[0009] To this end, the invention provides a robot comprising an electronic control unit and a hand having a plate carrying a plurality of contact-gripping elements connected to the electronic control unit. The gripping elements are arranged to hold the same object immobile in a The hand is guided by a first gripping configuration and a second gripping configuration distinct from the first gripping configuration. The electronic control unit is arranged to command the gripping elements to grasp the object by activating the first gripping configuration, then activating the second gripping configuration while keeping the first gripping configuration active, and then deactivating the first gripping configuration.

[0010] Thus, the change in gripping configuration is carried out in the robot's hand and, as the object remains fixed in the robot's hand during the change in gripping configuration, it is not necessary to use object detection means to know where the part is relative to the robot during and after the change in gripping configuration.

[0011] According to optional features, used individually or in whole or in combination: - the gripping elements include fingers mounted on the plate and at least part of which is associated with a motorization connected to the electronic control unit which is arranged to move the fingers, the fingers comprising at least a first pair of opposing fingers arranged to exert a clamping force along a first axis corresponding to the first gripping configuration; - the fingers include a second pair of opposing fingers arranged to exert a clamping force along a second axis distinct from the first axis, corresponding to the second gripping configuration; - at least one of the fingers includes a base mounted on the plate to pivot around an axis normal to the plate; - the plate comprises two parts, each bearing at least one of the fingers; - the two parts of the plate are movable relative to each other; - the two platinum parts are fixed relative to each other and form between them an angle of approximately 90°; - the gripping elements include a pneumatic suction cup arranged to suction a surface of the object in the second gripping configuration; - the gripping elements include a magnet arranged to magnetically attract a surface of the object in the second gripping configuration.

[0012] The invention also relates to a method of controlling such a robot.

[0013] Other features and advantages of the invention will become apparent from the following description of a particular and non-limiting embodiment of the invention. Brief description of the drawings

[0014] Reference will be made to the attached drawings, among which:

[0015] [Fig-1] is a schematic view of a robot according to the invention;

[0016] [Fig.2] is a perspective view of a hand of this robot, according to a first mode of realization ;

[0017] [Fig.3] is a perspective view showing the grasping of a part by said hand of the robot according to a first gripping configuration, this part resting on a support;

[0018] [Fig.4] is a view analogous to [Fig.3], the part having been detached from the support by the movement of the robot's hand;

[0019] [Fig.5] is a perspective view showing the first phase of a change in configuration of the part being gripped by the robot's hand, from a different viewing angle than that shown in figures 3 and 4;

[0020] [Fig.6] is a perspective view showing the second phase of the change of configuration of the part grasped by the robot's hand, from a different viewing angle than that of [Fig.5];

[0021] [Fig.7] is a perspective view showing the gripping of the part according to the second robot hand gripping configuration, the robot hand having been rotated to place the part in a different orientation;

[0022] [Fig.8] is a perspective view of the robot's hand, after release of the piece ;

[0023] [Fig.9] is a schematic elevation view of a robot hand, according to a second method of implementation;

[0024] [Fig. 10] is a schematic elevation view of a robot hand, according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] With reference to [Fig. 1], the invention is described herein in application to a robot comprising a rotating motorized base 1, a first segment 2 connected to the rotating motorized base 1 by a motorized joint 3, a second segment 4 connected to the first segment 2 by a motorized joint 5, a wrist 6 connected to the second segment 4 by a motorized joint 7, and a hand 8 attached to the wrist 6. The motorized joints 3, 5, and 7 are single-axis or multi-axis and incorporate motors connected to an electronic control unit 9 programmed to control the movements of the different parts of the robot. This robot architecture is known per se and will not be described in further detail here.

[0026] Also with reference to [Fig.2] and according to a first embodiment, the hand 8 here comprises a plate 10 and fingers 11 forming gripping elements.

[0027] The plate 10 comprises a first part of plate 10.1 and a second part of plate 10.2 which are rigidly connected to each other to form an angle of approximately 90° between them.

[0028] Each platinum part 10.1, 10.2 carries fingers 11 (denoted 11.1, 11.2 depending on whether they are carried by the platinum part 10.1 or by the platinum part 10.2). All the fingers 11 are identical here and each finger 11 comprises: a cylindrical housing 12 fixed to the plate 10, a base 13 mounted to pivot in the housing 12 around a central axis of the housing 12, a proximal phalanx 14 articulated on the base 13 around a first axis perpendicular to the central axis of the housing 12, an intermediate phalanx 15 articulated on the proximal phalanx 14 around a second axis perpendicular to the central axis of the housing 12, and a distal phalanx 16 articulated on the intermediate phalanx 15 around a third axis perpendicular to the central axis of the housing 12. The finger 11 also comprises a first motor driving the base 13 in rotation relative to the housing 12 and a second motor to move each phalanx.The second motorization may include as many actuators as joints or a number of actuators less than the number of joints (in which case finger 11 is said to be under-actuated). The motorizations are connected to the electronic control unit 9, which is programmed to move the fingers 11 in order to implement the control method according to the invention.

[0029] The fingers 11 are arranged to hold the same object immobile in an x, y, z frame of the hand 8 by a first gripping configuration and a second gripping configuration distinct from the first gripping configuration, and the electronic control unit 09 is arranged to command the fingers 11 to grasp the object by activating the first gripping configuration, then activating the second gripping configuration while keeping the first gripping configuration active, then deactivating the first gripping configuration.

[0030] The control method of the invention will now be described in detail in relation to the grasping of an object consisting of a parallelepiped piece 200 having two large sides 201 and two small sides 202 bordering two main faces 203.

[0031] At the initial moment, the part 200 rests on a support 300 by one of its main faces 203 and the gripper 8 is approached to grasp the part 200 by activating the first grasping configuration ([Fig.3]).

[0032] The first gripping configuration consists of applying the free end of the distal phalanges 16 of fingers 11.1 in opposition against the two long sides 201. Each of the fingers 11.1 is thus oriented around the axis of the housing 12 to form two pairs of opposing fingers 11.1 and the fingers 11.1 of each of the pairs of fingers are controlled to pinch part 200 between them by applying the free ends of the distal phalanges 16 of the fingers 11.1 against the two long sides 201. The fingers 11.1 thus hold part 200 in a fixed position in the x, y, z coordinate system of the hand 8. The fingers 11.2 are controlled to be in a spread-out position so as not to interfere with either the fingers 11.1 or with part 200.

[0033] The robot is then commanded to move the hand 8 so as to lift the part 200 and move it away from the support 300 ([Fig. 4]) in order to perform one or more operations on the part 200, the details of which are irrelevant to the invention. It should be noted that the fingers 11.2 have been moved as far away from the part 200 as possible so as not to obscure it or hinder the approach of a tool or the view of the part, depending on the operation to be performed (for example).

[0034] The electronic control unit 9 then activates the second gripping configuration by commanding the fingers 11.2 to apply the free ends of the distal phalanges 16 of fingers 11.2 in opposition against the two main surfaces 203 ([Fig. 5]). During this operation, the first gripping configuration remains activated so that the distal ends of all fingers 11.1, 11.2 are in contact with the part 200, whose position in the x, y, z coordinate system is unchanged.

[0035] The electronic control unit 9 then deactivates the first gripping configuration by commanding the fingers 11.1 to move the free ends of the distal phalanges 16 of the fingers 11.1 away from the long sides 201 of the part 200 ([Fig. 6]). During this operation, the second gripping configuration remains activated so that the distal ends of all the fingers 11.2 are in contact with the part 200, whose position in the x, y, z coordinate system remains unchanged.

[0036] The robot is then commanded to move the hand 8 so as to perform one or more operations on the part 200, the content of which is irrelevant to the invention. It should be noted that the fingers 11.1 have been folded back against the plate 10.1 and the housings 12 in such a way that they do not obscure the part 200 and do not hinder the approach of a tool (for example).

[0037] After the operation or operations in question have been carried out, the robot is commanded to place the part 200 on the support 300 but with a final orientation different from the initial orientation: the part 200 must be placed so as to rest by one of the long sides 201 on the support 300.

[0038] The electronic control unit 9 then commands the robot to operate a pivot of the wrist 6 so as to present said large side 201 downwards and then to move the hand 8 so as to place said large side 201 on the support 300 ([Fig.7]).

[0039] Once the large side 201 is on the support 300, the electronic control unit 9 commands the deactivation of the second gripping configuration by opening the fingers 11.2 in opposition so as to release the part 200 ([Fig.8]).

[0040] The two other embodiments of the hand 8 will now be described in relation to figures 9 and 10.

[0041] In these, the hand 8 includes a plate 10 on which are articulated fingers 11 in opposition controlled to grasp the part according to a first gripping configuration similar to that previously described.

[0042] In the second embodiment of [Fig.9], the hand includes an additional gripping element in the form of an electromagnet 20 here mounted on a telescopic actuator 21 extending in a median position between the fingers 11.

[0043] When the first gripping configuration is activated and the part is grasped by the fingers 11, the part 200 has one of its surfaces 203 facing the permanent magnet 21 but at a distance from it.

[0044] The electronic control unit 9 then activates the second gripping configuration by commanding the extension of the telescopic actuator 21 to bring the electromagnet 20 into contact with the main surface 203 opposite and the power supply to the electromagnet 20 to attract the part 200 (which must obviously be in a material containing iron or nickel).

[0045] The electronic control unit 9 then deactivates the first gripping configuration by commanding the fingers 11 to release the part 200. During this operation, the second gripping configuration remains activated so that the position of the part 200 in the x, y, z coordinate system is unchanged.

[0046] In the third embodiment of [Fig.9], the hand includes an additional gripping element in the form of at least one suction cup 30 here mounted on the plate 8 in a median position between the fingers 11. The suction cup 30 is connected to a vacuum circuit via a valve controlled by the electronic control unit.

[0047] The operation is similar to that of the second embodiment.

[0048] Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0049] In particular, the robot may have a different structure from that described and comprise more or fewer segments, or be of the hexapod type.

[0050] The hand may have a different structure from that described and include more or fewer fingers.

[0051] The fingers may not be mounted pivotally on the plate.

[0052] Some fingers can be replaced by a fixed stop pin mounted opposite one of the articulated fingers, the part being pinched between the fixed stop pin and the articulated finger according to the first gripping configuration.

[0053] The gripping elements may have a different structure from that described and include, for example, an electrostatic gripper.

[0054] The plate can be in one piece or comprise several parts of plates fixed relative to each other, or movable relative to each other manually for adjustment purposes or motorized to adapt the shape and / or dimensions of the plate to the shape of the part to be gripped.

[0055] The electronic control unit 9 may include a processor and memory containing a computer program executable by the processor, a dedicated ASIC-type processor, and an FPGA-type programmable logic array. The electronic control unit 9 may be centralized for all motors or may include a subunit for controlling the arm joints and a subunit for controlling the hand. The subunit for controlling the hand may be located on the hand, as close as possible to the motor(s) being controlled.

[0056] The robot can include means for detecting parts to be grasped in order to have relative autonomy in grasping (for example when parts arrive without a predefined orientation on a conveyor) or on the contrary be completely slave (for example when each part to be grasped is arranged in a precise position and orientation).

Claims

Demands

1. Robot comprising an electronic control unit (9) and a hand (8) having a plate (10) carrying a plurality of contact gripping elements (11, 20, 30) connected to the electronic control unit (9), characterized in that the gripping elements (11, 20, 30) are arranged to hold the same object immobile in a frame (x, y, z) of the hand (8) by a first gripping configuration and a second gripping configuration distinct from the first gripping configuration, and in that the electronic control unit (9) is arranged to command the gripping elements (11, 20, 30) to grasp the object by activating the first gripping configuration, then activating the second gripping configuration while keeping the first gripping configuration active, then deactivating the first gripping configuration.

2. Robot according to claim 1, wherein the gripping elements (11, 20, 30) comprise fingers (11) mounted on the plate (8) and at least a part of which is associated with a motorization connected to the electronic control unit (9) which is arranged to move the fingers, the fingers (11) comprising at least a first pair of opposing fingers (11.1) arranged to exert a clamping force along a first axis corresponding to the first gripping configuration.

3. Robot according to claim 2, wherein the fingers (11) comprise a second pair of opposing fingers (11.2) arranged to exert a clamping force along a second axis distinct from the first axis, corresponding to the second gripping configuration.

4. Robot according to claim 2 or 3, wherein at least one of the fingers (11) comprises a base (13) mounted on the plate (10) to pivot about an axis normal to the plate (10).

5. Robot according to claim 2 or 3 or 4, wherein the plate (10) comprises two parts (10.1, 10.2) each carrying at least one of the fingers (11.1, 11.2).

6. Robot according to claim 5, wherein the two platinum parts (10.1, 10.2) are movable relative to each other.

7. Robot according to claim 5, wherein the two platinum parts (10.1, 10.2) are fixed relative to each other and form an angle of approximately 90° between them.

8. Robot according to claim 2, wherein the gripping elements include a pneumatic suction cup (30) arranged to suction a surface of the object in the second gripping configuration.

9. Robot according to claim 2, wherein the gripping elements include a magnet (20) arranged to magnetically attract a surface of the object in the second gripping configuration.

10. A method for controlling a robot according to any one of the preceding claims, comprising the steps of: - controlling the gripping elements (11, 20, 30) to grasp an object by activating the first gripping configuration, - then controlling the gripping elements (11, 20, 30) to grasp the object by activating the second gripping configuration while keeping the first gripping configuration active, - then controlling the gripping elements (11, 20, 30) to partially release the object by deactivating the first gripping configuration.

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