Reorientable robotic gripper

Abstract

Reorientable robotic gripper (1) intended for a robotic arm (4) which has at least one degree of freedom and which further includes at one of its ends a gripper attachment interface (5), this gripper (1) having a base (3) equipped with a removable fixing device adapted to be mounted on the gripper attachment interface (5) of the robotic arm (4), the base (3) extending along an axis (A3) from the interface (5) of the robotic arm, this gripper (1) being adapted to grasp an object (2) and to modify the orientation of the grasped object relative to the base (3), this gripper (1) having: – a curved motion guide (9) carrying a movable support (10) which is adapted to describe a curved trajectory relative to the base (3); – an object grasping device (14) mounted for rotation around an axis of rotation (A14) on the movable support (10). Figure for the abbreviation: Fig.1

Description

Title of the invention: Reorientable robotic gripper technical field

[0001] The invention relates to the field of robotics and more specifically to the field of gripping accessories adapted to be mounted removably at the end of robotic arms.

[0002] The invention relates more particularly to reorientable robotic grippers, which have the ability to modify the position and orientation of a grasped object relative to their base. These grippers, which fall within the broader category of dexterous grippers, reproduce at least partially the ability of the human hand to manipulate an object after grasping it, so as to orient it in particular directions.

[0003] A prime example of dexterous manipulation is that of a human hand screwing in a nut or a light bulb. This operation involves complex and coordinated movements of the arm, wrist, and fingers, the fingers being capable of both translating the object and rotating it.

[0004] Reorientable robotic grippers are adapted to reproduce at least partially these capabilities. PREVIOUS ART

[0005] Most robotic grippers used in industry are not dexterous; that is, they consist of only a simple grasping element, which is thus located at the end of a robotic arm. Once the object is grasped, it cannot be repositioned relative to the gripper itself, and only the joints of the robotic arm allow the grasped object to move. Combined with vision systems or other sensors, these grippers are widely used in industry and are satisfactory for simple and repetitive tasks. However, they do not allow the reorientation of grasped objects and are therefore not suitable for complex tasks requiring gripper dexterity.

[0006] There are also dexterous grippers, which generally have several fingers. Each finger is usually equipped with two or three joints, or even more, allowing complex movements through finger coordination. These grippers allow the repositioning and reorientation of a grasped object within the gripper itself, without involving the joints of the associated robotic arm. These devices include anthropomorphic grippers with five fingers, attempting to reproduce the behavior of the human hand as closely as possible. These grippers can thus manipulate objects between their fingers to rotate them, reposition them, observe, etc. These grippers are, however, complex and are primarily developed in research laboratories. For example, these grippers can implement up to 20 degrees of freedom or more, and up to 42 associated motors. Due to their numerous joints and motors, they are fragile and require costly maintenance. Their high complexity leads to significant costs and reliability that is difficult to control, and they are therefore currently little used in industry. Description of the invention

[0007] The invention aims to improve prior art robotic grippers.

[0008] To this end, the invention relates to a reorientable robotic gripper for a robotic arm having at least one degree of freedom and further comprising at one of its ends a gripper attachment interface, this gripper comprising a base equipped with a removable fastening device adapted to be mounted on the gripper attachment interface of the robotic arm, the base extending along an axis from the interface of the robotic arm, this gripper being adapted to grasp an object and to modify the orientation of the grasped object relative to the base. This gripper comprises: - a curved motion guide carrying a movable support adapted to describe a curved trajectory relative to the base; - an object grasping device mounted to rotate about an axis of rotation on the moving support.

[0009] The invention makes it possible to decompose the functions performed by a robotic gripper, so as to obtain a gripper capable of grasping, manipulating and facilitating the use of an object, by maximizing the capabilities of the gripper, while limiting its level of complexity.

[0010] The invention is particularly suited to the deployment of dexterous gripping solutions in industry, with a gripper combining the following capabilities: - the gripping itself, which consists of grasping in the most stable way possible the most varied objects possible, whether with regard to their shape, size or weight; - the manipulation of the gripped objects, which consists of reorienting and moving the gripped objects within the gripper itself, if possible at high speed and over large amplitudes. This manipulation makes it possible to position and orient the gripped object in a more favorable configuration to carry out the desired tasks; - the use of captured objects, whether to gather information about the environment (for example, when the captured object is a camera), or to act on the environment with the captured object (for example, to perform insertion or screwing tasks, which is a very widespread need in industry). In the industrial sector, this use includes screwing screws or nuts into... In hard-to-reach environments, the insertion of special connectors or clips, etc., or, in agriculture, the complex movements required, for example, to pick fruits or vegetables.

[0011] These three different types of actions are often confused and / or considered together, and the performance of robotic grippers is generally evaluated only with regard to their gripping capabilities, without explicitly considering the manipulation of the grasped objects or the actions performed on the environment. Generally, it is the robot on which the gripper is mounted, and not the gripper itself, that allows the objects to be reoriented.

[0012] On the contrary, the invention makes it possible to reproduce effectively both these grasping and manipulation movements, efficiently and robustly, while allowing effective use of the grasped objects.

[0013] In particular, the particular arrangement of a base, means of movement and orientation (curved movement guide, plurality of optional curved and mobile rotating arms, optional repositioning table, etc.), a mobile support, and an object grasping member, allows a reorientation of the grasped object in particular in order to take advantage of the rotation of the interface (when it is a rotating interface) of the robotic arm carrying the gripper (the base is then mounted on a rotating gripper attachment interface which allows the rotation of this base around an axis), or the rotation of the grasping member around an axis integrated into the gripper. Parts can then be grasped so that, after reorientation, they are in the center of the gripper and in alignment with its base, which is driven in rotation by the interface (when it is a rotating interface) of the robotic arm, or in alignment with an axis of the gripper.The movements of the robotic arm are then limited to bringing the grasped object to the place where it is to be used; this use can then take place by a rotational movement of the base, using the rotation of the interface (when it is a rotating interface) of the robotic arm, or by a rotational movement around an axis integrated into the gripper, in both cases with very little or no stress on the other joints of the robotic arm, thanks to the reorientation of the grasped object.

[0014] According to a particular embodiment, the base can be mounted on a rotating gripper attachment interface that allows the rotating base to be rotated around an axis. For example, nuts gripped obliquely and / or offset from the center of the gripper can be reoriented and / or repositioned so that they can be screwed on simply by rotating an axis, with the option of this axis being located on the gripper or on the robotic arm. A complex screwing operation, following a random gripping operation, can thus be reduced, after appropriate reorientation and / or repositioning, to a simple rotation of an axis, rather than coordinated and large-amplitude movements of several or even all axes of the robotic arm.

[0015] The invention thus allows a grasping, a reorientation, and a use of the grasped objects made simple by the ability to align, or on the contrary to separate, the axis of the base of the gripper (which makes it possible to take advantage if necessary of a possible rotating interface of the robotic arm), or an axis of the gripper itself, and the axis of the object grasping organ, or a particular axis of the object itself.

[0016] The invention, by focusing on the functions of grasping, manipulating and using grasped objects, by decoupling and simplifying them, goes against the current paradigm in robotics, which consists of drawing inspiration from biomimicry and getting closer to the human hand when it comes to performing complex dexterous functions.

[0017] Fine manipulation, while ensuring the stability of the objects grasped, requires in this case perfect control of the movements of the grasping organs, which is very difficult or even impossible with the dexterous systems of the prior art comprising several dozen motors to coordinate and transmissions which introduce friction and hysteresis phenomena.

[0018] The gripper according to the invention may include the following additional features, alone or in combination:

[0019] - the curved trajectory of the moving support relative to the base includes at least a position in which the mobile support is positioned on the axis of the base;

[0020] - the curved motion guide is arranged so that the trajectory of the support mobile includes: at least one position in which the axis of rotation of the object grasping member is parallel to the axis of the base; and at least one position in which the axis of rotation of the object grasping member forms an angle with the axis of the base;

[0021] - the trajectory of the moving support includes: at least one position in which the axis of rotation of the object grasping member coincides with the axis of the base; and at least one position in which the axis of rotation of the object grasping member is concurrent with and forms an angle with the axis of the base;

[0022] - the curved motion guide comprises a circular arc portion, the support mobile thus exhibiting a portion of semi-circular trajectory;

[0023] - the trajectory of the moving support includes at least one position in which the axis the rotation of the object grasping device forms essentially a right angle with the axis of the base;

[0024] - the curved motion guide comprises a curved slide, and the movable support is formed by a slide engaged on this curved slide;

[0025] - the curved motion guide has a cantilevered portion such that said slide has a portion arranged opposite the axis of the base;

[0026] - the curved movement guide comprises at least two arms articulated by a pivot, one of the arms being fixed on the base, and another of the arms carrying the mobile support at its end, the mobile support then presenting a circular trajectory centered on said pivot;

[0027] - at least one of said arms is curved;

[0028] - the curved movement guide includes a suitable repositioning table to adjust its position along at least one direction in a plane intersecting the axis of the base;

[0029] - said repositioning table is adapted to adjust the position of the guide of curved movement along at least one direction in a plane perpendicular to the axis of the base;

[0030] - the curved motion guide includes an additional axis of rotation between said repositioning table and the rest of the curved movement guide;

[0031] - a pivot is mounted on the movable support, the object grasping member being mounted on this pivot;

[0032] - the object grasping device comprises a gripper including a base on which are mounted grasping fingers;

[0033] - said gripping fingers are telescopic;

[0034] - said clamp comprises two opposing grasping fingers;

[0035] - the two gripping fingers are adapted to grip onto an axis in such a way asymmetrical with respect to the axis of rotation of the object grasping device;

[0036] - the gripper includes rotary repositioning elements at the end of the grasping fingers, adapted to rotate the grasped object around an axis substantially orthogonal to the axis of rotation of the object grasping organ;

[0037] - the rotary repositioning elements comprise a clamping disc mounted on each grasping finger by a pivot;

[0038] - the object grasping device includes a repositioning table adapted to adjust its position along at least one direction in a plane intersecting the axis of rotation of the object grasping device;

[0039] - the repositioning table is adapted to adjust the position of the grasping member of object in at least one direction in a plane perpendicular to the axis of rotation of the object grasping device;

[0040] - the object grasping device comprises an additional axis of rotation between said repositioning table and the rest of the object capture device;

[0041] - the gripper includes a vision device adapted to control the modification of the position and / or orientation of the object being grasped relative to the base;

[0042] - the base is a rotating base around its axis. PRESENTATION OF THE FIGURES

[0043] Other features and advantages of the invention will become apparent from the following non-limiting description, with reference to the accompanying drawings in which:

[0044] - [Fig. 1] is a perspective view of an example of a gripper according to the invention;

[0045] - [Fig.2] illustrates another example of the gripper according to the invention;

[0046] - [Fig.3] illustrates the gripper of [Fig.1] in a different position;

[0047] - [Fig.4] illustrates another example of the gripper according to the invention;

[0048] - [Fig.5] illustrates the gripper of [Fig.4] in a different position;

[0049] - Figures 6, 7, 8, and 9 illustrate further examples of gripper according to the invention;

[0050] - [Fig. 10] illustrates the grasping of an object by the gripper;

[0051] - Figures [Fig. 11] and [Fig. 12] illustrate further examples of the gripper according to the invention;

[0052] - [Fig. 13] illustrates the gripper of [Fig. 12], devoid of its grasping organ;

[0053] - [Fig. 14] illustrates another example of the gripper according to the invention;

[0054] - [Fig. 15] illustrates the gripper of [Fig. 1] in a different position;

[0055] - Figures [Fig. 16] and [Fig. 17] illustrate a robotic arm equipped with a gripper according to the invention during operation;

[0056] - [Fig. 18] illustrates a gripper according to the invention, the object gripped being a tool;

[0057] - Figure 19 illustrates a gripper according to the invention, with a gripped object which is asymmetrical;

[0058] - [Fig.20] illustrates a gripper according to the invention, the object gripped being another tool.

[0059] The similar and common elements in the various examples and embodiments they carry the same reference numbers to the figures. DETAILED DESCRIPTION

[0060] The invention relates to a reorientable robotic gripper, that is to say a gripper in the field of robotics which is adapted to grasp an object and to manipulate it within itself.

[0061] This robotic gripper 1, being reorientable, is adapted to modify the orientation and / or position of the grasped object relative to its base 3. Thus, after grasping an object 2, the gripper 1 allows an internal reconfiguration allowing this grasped object 2 to be moved and in particular to modify its position and / or angular orientation relative to the base 3 to allow simplified use of the grasped object 2.

[0062] The robotic gripper is intended for a robotic arm 4 which has at least one degree of freedom and which further includes at one of its ends a gripper attachment interface 5. The gripper 1 includes a base 3 equipped with a removable fastening device adapted to be mounted on the gripper attachment interface 5. The gripper 1 is therefore adapted to grasping an object 2 and to modifying the orientation of the grasped object relative to the base 3 by means of: - a curved motion guide 9 carrying a movable support 10 which is adapted to describe a curved trajectory relative to the base 3; - an object grasping device 14 mounted mobilely in rotation, around an axis of rotation A14, on the mobile support 10.

[0063] The base 3 extends from the interface 5 of the robotic arm along an axis A3, illustrated in the figures. The axis A3 is a longitudinal axis through which the base 3 and the interface 5 are coupled.

[0064] In one embodiment, the robotic gripper is associated with a robotic arm 4 that has at least one degree of freedom and further includes at one of its ends a gripper attachment interface 5, which is a rotating interface. The gripper 1 then includes a base 3 equipped with a removable fastening device adapted to be mounted on the (rotating) gripper attachment interface 5 of the robotic arm, so as to be movable in rotation about the axis A3. The axis A3 is then an axis of rotation. In this case, the gripper has an optional, particularly advantageous feature in which the trajectory of the curved motion guide includes at least one position in which the movable support 10 is positioned on the axis A3 of the base 3, which is then an axis of rotation.

[0065] Note that when the turntable 5 is not rotating, the axis A3 is also present, as the last axis of the robotic arm, but is simply no longer an axis of rotation.

[0066] Alternatively, according to another embodiment, the gripper can be associated with a robotic arm 4 which has a non-rotating interface 5. The axis A3 is then a longitudinal axis. In this case, either the gripper itself has a pivot about axis A3 allowing the curved guide 9, the mobile support 10 and the gripping member 14 to rotate about axis A3, or the gripper does not have such a pivot and then, since interface 5 is not a rotating interface, axis A3 is not used.

[0067] Figures 1 to 11 and 15 to 17 illustrate examples where the grasped object is a nut that can then be screwed into a suitable location thanks to the dexterity properties of the gripper 1, in different positions, at different working angles, and taking into account environmental constraints. The nut is a particularly interesting illustrative example of an object requiring dexterity to be screwed in under difficult conditions. However, the invention also applies, with the dexterity provided, to any other object to be grasped and manipulated.

[0068] The gripper 1 is intended to be mounted on a robotic arm 4 which has at least one degree of freedom and which has, in addition to this degree of freedom, at one of its ends, a gripper attachment interface 5.

[0069] Figures 16 and 17 illustrate an example of a complete robotic arm 4, and the other figures represent only the end of the robotic arm 4.

[0070] The robotic arm 4 can implement any known kinematic chain allowing the movement of an end equipped with the interface 5 along at least one degree of freedom. The robotic arm is, for example, a multi-jointed arm comprising several rotational degrees of freedom in series (advanced multi-jointed arms generally comprise 6 to 8 rotational degrees of freedom in series and allow the positioning of the interface 5 located at their end in numerous positions and orientations). The robotic arm can also advantageously include, at its base, a parallel robot structure, for example of the "Delta" type, or a Cartesian XYZ structure, on which are located other axes of translation or rotation, and an end equipped with an interface 5. The robotic arm can also be extremely simple, with only one degree of freedom in addition to its interface 5, such as a rotating axis, or a rail.Parallel robots (such as "Gough-Stewart" type platforms, for example) or any other mechanism suitable for forming such a robotic arm can also be used.

[0071] In the illustrative example in the figures, the robotic arm 4 is a multi-jointed arm, the end of which includes the interface 5. If the interface 5 is a rotating interface, the interface 5 is mounted on the end 7 of the robotic arm 4 by means of a pivot 6 and a suitable motorization (not visible in the figures).

[0072] In the illustrative example in the figures, in a completely optional manner, the end 7 of the robotic arm 4 which carries the interface 5 is itself mobile in rotation along an axis A7 relative to an anterior portion 8 of the robotic arm 4.

[0073] Whatever the arrangement of the robotic arm 4, the latter therefore has an interface 5 at its end, allowing the gripper 1 to be mounted there, which will be adapted for the work for which the robotic arm 4 is intended.

[0074] The base 3 of the gripper 1 includes a removable mounting device adapted to be mounted on the interface 5 of the robotic arm 4. This removable mounting device can be any known means of mounting a tool on industrial equipment. The gripper 1 is, in fact, a tool that grasps objects 2 (these objects 2 may themselves be tools) to perform an action on the environment (physical action or information gathering, for example, if object 2 is a camera), in conjunction with the robotic arm 4. This mounting device can be implemented, for example, by a mounting plate mounted on the interface 5. This mounting plate is thus rotatable when the interface 5 is a rotating interface, and adapted to rotate the gripper 1 that will be mounted on this plate. The mounting can be carried out by production means such as quick-release tool holders by clipping or angular locking, by toggle devices, by screws, or by any other means.

[0075] The operation of mounting the gripper 1 on the interface 5 can be carried out by automated or manual means, or directly by the robotic arm 4, which itself retrieves the gripper 1 from a tool store, by connecting directly to it.

[0076] The gripper 1 is thus mounted directly in place of the conventional gripping means on a robotic arm 4. The gripper 1 has at least two motorized and controlled degrees of freedom, including at least one axis of rotation A14, and is associated in a conventional manner with appropriate control electronics.

[0077] When the interface 5 is a rotating interface, the base 3 of the gripper 1 is adapted to be pivoted around the axis A3, which is then advantageously coincident with the axis of rotation of the interface 5.

[0078] Fig. 1 and Fig. 3 illustrate, for example, two different angular positions of the gripper 1 thanks to the pivoting allowed around the axis A3 by the interface 5.

[0079] Depending on the robotic arm 4 on which the gripper 1 will be mounted, the base 3 has a continuous rotation capacity in both directions (suitable for example for screwing or unscrewing a screw or nut), or a rotation limited to a certain angular sector (suitable for example for setting up elements to be locked by rotation of a predetermined angle).

[0080] The gripper 1 further comprises a curved motion guide 9 which carries a movable support 10. The curved motion guide 9 is an element defined as being capable of imparting to the movable support 10 a curved trajectory relative to the base 3. This curved trajectory ensures that the grasped object 2 can undergo an angular reorientation along at least one axis, after its grasping.

[0081] The trajectory is defined at a minimum as being curved, that is to say, not rectilinear. This trajectory can also be, more precisely, for example, circular, which offers additional advantages.

[0082] The curved movement guide 9 can be made up of any mechanical element adapted to guide and motorize the movement of the mobile support 10, so that on the one hand this mobile support 10 can be moved, and on the other hand this movement takes place along the defined curved trajectory.

[0083] Within the framework of the invention, this curved trajectory contributes to the reorientable character of the gripper 1 by being one of the components which allow, by this curved trajectory, the change of angular orientation of the grasped object 2.

[0084] When the interface 5 is a rotating interface, the curved motion guide 9 is further arranged to optionally allow the mobile support 10 to follow a trajectory including at least one position where it is parallel to the axis A3 of rotation of the base 3, and advantageously disposed on the axis A3. The movable support 10 is considered to be disposed on the axis A3 when a portion of the movable support 10 is cut by the axis A3, as illustrated in figures 3 and 5.

[0085] The curved movement guide 9 is for example made by a slide 12 or a curved rail, as in the example of figures 1 to 3, 6 to 9, and 11 to 20. Such a slide 12 then has a curved shape for its function, and is fixed on the base 3. Advantageously, the slide 12 is semi-circular in shape to allow movement of the movable support 10 along an arc of a circle.

[0086] In this case, the movable support 10 consists of a suitably shaped slide, mounted on the slide 12, for example, by low-friction or roller bearings. In the illustrated examples, the slide 12 has a cantilevered portion 13 allowing a section of the slide 12 to be positioned facing the axis A3 (which is particularly advantageous when the interface 5 is a rotating interface). This provides a simple solution for allowing the movable support 10 to occupy a position where it is positioned on the axis A3, as illustrated in [Fig. 3].

[0087] The mobile support 10 is motorized on the slide 12 and controlled by a control electronic, so that the position of the mobile support 10 on the slide 12 is servo-controlled, in coordination with the other axes of the gripper itself and of the robotic arm 4.

[0088] Another concrete example of an embodiment of the curved motion guide 9 is illustrated in Figures 4 and 5. In this example, the curved motion guide 9 comprises several curved arms that are movable and rotate. In this example, the curved motion guide 9 comprises a first arm 9A which is fixed to the base 3 and a second arm 9B, connected by a pivot 11 to the first arm 9A. Preferably, at least one of the two arms 9A, 9B is curved. The movable support 10 is fixed on the second arm 9B, at its end opposite the pivot 11. The movable support 10 is thus also adapted to describe a curved trajectory relative to the base 3. In this example, it is a circular trajectory centered around the pivot 11. This trajectory of the movable support 10 also includes a position in which the movable support 10 is arranged on the axis A3 of the base, when the interface 5 is a rotating interface, as illustrated in [Fig.5] in which the axis A3 passes through the movable support 10. .

[0089] The pivot 11 is motorized and controlled by a control electronic, so that the orientation of the mobile support 10 relative to the base 3 is servo-controlled, in coordination with the other axes of the gripper itself and of the robotic arm 4.

[0090] Beyond these examples, the curved motion guide 9 can be implemented by any other curved rotation or translation device allowing the movable support 10 to follow a curved trajectory, preferably semi-circular, relative to the base 3, for example a series or parallel structure with cylindrical or spherical output movement, or a ball joint device, this trajectory optionally including at least one position in which the movable support 10 is positioned on the axis A3 of the base 3.

[0091] The gripper 1 further comprises an object grasping member 14, which is mounted movably in rotation on the movable support 10.

[0092] The mounting of the gripping element 14 on the mobile support 10 can be achieved by any means allowing controlled rotation of the gripping element 14 relative to the mobile support 10, around an axis A14. This mounting can notably be achieved in a conventional manner in robotics, by a motorized pivot 25 mounted on the mobile support 10 and on which the gripping element 14 is mounted. This motorized pivot 25 can be a bearing-mounted assembly associated with an onboard or remote motor.

[0093] The grasping device 14 can be any device enabling the grasping of an object 2 in the manner required for the intended application.

[0094] The invention lends itself to the implementation of both simple and complex grasping organs 14. However, one of the advantages of the invention is to allow dexterous movements of reorientation and readjustment of the grasped objects 2 within the gripper 1 with simple grasping organs 14, whereas these dexterous movements are reserved in the prior art for very complex grasping organs such as anthropomorphic robotic hands.

[0095] By way of illustrative examples, the seizure device 14 may include, in particular: - a two-finger gripper 15A and 15B, illustrated in particular in the examples of figures 1 and 2; - a three-finger gripper 15 with gripping fingers 15A, 15B, 15C, as illustrated in the example in [Fig.6]; - a 15-pronged clamp with a greater number of gripping fingers; - a magnetic gripping device 14, allowing the gripping of ferromagnetic objects 2 (a nut in the illustrated example), as in the example of [Fig.7]; - a grasping member 14 comprising at least one flexible deformable portion 16, as in the example of [Fig.8]; these flexible deformable portions 16 are common in the field of robotics and are formed for example by electro-active polymers or flexible deformable bodies provided with internal channels which, by variation of the pressure of a fluid in these internal channels, cause a tightening or loosening of the flexible deformable body 16 on the grasped object 2.

[0096] The grasping element 14 could also consist of a vacuum pouch (i.e., a flexible pouch capable of deforming to conform to the shape of an object to be grasped and filled with a fine powder consisting, for example, of coffee grounds or apricot kernel powder), this pouch being connected to a device allowing to create a vacuum within it, so as to compress and render almost rigid the powder filling this pocket, thus ensuring a firm grip on the object) arranged in place of the magnetic gripping element 14 of [Fig. 7], and it could comprise several vacuum pockets attached to the end of all or part of the gripper fingers of the gripper 15, whether the gripper 15 has two fingers, three fingers, or more than three fingers. Such vacuum pockets could also be arranged on all or part of the bodies constituting the gripper fingers and the body of the gripper, and not only at the ends of the gripper fingers.

[0097] The invention allows the implementation of a grasping member 14 which can be specific to a particular type of object or which can, on the contrary, be adaptable for a large number of objects to be grasped.

[0098] In the example illustrated in Figures 2, 4, 5, 19, and 20, the gripper 15 comprises two opposing grasping fingers 15A, 15B movable relative to a base 17. These fingers are simple, made of a single piece (but could also be made using several mechanical parts assembled together, and / or could optionally include removable jaws), and act by bringing them together or moving them apart. The closure of the grasping fingers 15A, 15B can be symmetrical and centered around the median plane of the base 17 or, alternatively, it can be asymmetrical, i.e., the grasping fingers 15A, 15B close while centered on an axis that is offset from the axis A14 of the grasping member 14 (as illustrated in [Fig. 19]). Symmetrical closure can, for example, be achieved when the movements of the gripping fingers are coupled and controlled by the same motor.An asymmetrical closure generally requires the use of two independent motors to control the movements of the gripping fingers 15A and 15B.

[0099] In the example illustrated in [Fig.9], the gripper 15 has two opposing gripping fingers 15A, 15B movable on a base 17, these gripping fingers 15A, 15B being telescopic with a retractable and deployable portion 18, adding an additional degree of freedom in gripping an object 2, or two if these telescopic movements are independent.

[0100] In the example illustrated in figures 1, 3, 11, 12, and 14 to 18, the gripper 15 comprises two opposing gripping fingers 15A, 15B movable on a base 17, with further rotating repositioning elements 19 mounted at the end of the fingers 15A, 15B.

[0101] The rotary repositioning elements 19 are, in this example, the terminal elements enabling the grasping of the object 2. These rotary repositioning elements 19 grasp the object 2, and provide an additional degree of freedom to the object 2, after its grasping, in rotation relative to the base 17.

[0102] Thanks to the rotating repositioning elements 19, the gripped object 2 is therefore rotationally mobile within the gripping member 14 (in this example, it is mobile relative to the base 17) and therefore in relation to the mobile support 10. The rotating repositioning elements 19 are adapted to rotate the grasped object 2 around an axis substantially orthogonal to the axis of rotation A14 of the grasping organ 14.

[0103] The mounting of the rotary repositioning elements 19 on the gripping fingers 15A, 15B can be achieved by any known mechanical means of pivot connection with motorization. In the illustrated example, the rotary repositioning element 19 consists of a clamping disc 20 mounted on a motorized and controlled pivot 21, which is fixed to the end of the gripping fingers 15A, 15B of the gripper 15.

[0104] Thanks to the rotating repositioning element 19, the gripper 1 benefits from an additional possibility of reorienting the gripped object 2, which can be advantageous for example for gripping objects 2 in bulk and in random angular orientations, as in the example of [Fig. 10] which illustrates the gripping of nuts arranged in a pile.

[0105] Once this object 2 is gripped, as illustrated for example in [Fig. 1], a rotation of the rotary repositioning element 19 can be driven to bring the gripped object 2 into another angular position, appropriate to the intended work. In the illustrated example, the rotary repositioning element contributes to positioning the screw axis of the nut on an axis parallel to, or coinciding with, the axis A14 of the gripping member.

[0106] The different types of object grasping members 14 can of course be combined. For example, the grasping member 14 can be a gripper 15 with two opposing grasping fingers 15A, 15B, which are also telescopic, and which have at their end rotating repositioning elements 19, as in the example illustrated in [Fig. II],

[0107] The movements of the curved movement guide 9 in rotation, of the mobile support 10, of the gripping member 14 (possibly with asymmetric grip), and of the possible rotating repositioning element 19, can be combined to bring the gripped object 2 into a particular working orientation (for example a nut oriented with its screw axis coincident with a rotation axis of the gripper 1).

[0108] The example illustrated in [Fig. 11] further includes a covering of elastic cushions 22 arranged on the clamping discs 20 of the rotating repositioning element 19, to conform to the shape of the grasped object 2, and / or to measure the grasping forces if it is instrumented for this purpose.

[0109] When the interface 5 is a rotating interface, the trajectory of the mobile support 10, permitted by the curved motion guide 9, allows the gripper to assume different configurations, including configurations where: - the rotation axis A14 of the gripping member 14 and the axis A3 of the base 3 are disjoint, that is to say that these two axes A3, A14 are not parallel, as in the example of figures 1, 2, 4, 6 to 9, 11, 12, 14, 15, and 17 to 20; - the rotation axis A14 of the gripping member 14 and the axis A3 of the base 3 are parallel, as in the example of figures 3, 5, and 16.

[0110] As illustrated in the figures, preferably, the curved motion guide 9, the movable support 10, and the gripping member 14 are arranged so that these axes A3, A14 are concurrent, which simplifies the control of the axes. The second configuration indicated previously (axes A3, A14 parallel) is then a configuration where these axes A3, A14 coincide.

[0111] The gripping member 14 may further include a repositioning table 23 in a plane intersecting and advantageously perpendicular to the axis of rotation A14 of the gripping member 14. The repositioning table 23 allows the position of the gripping member 14 to be adjusted in at least one direction in said plane intersecting and advantageously perpendicular to the axis A14. The movement of the gripping member 14 in this plane may be along one or more axes, and rectilinear or curved.

[0112] In the example of [Fig. 12], the gripping member 14 is equipped with such a repositioning table 23, and [Fig. 13] is an identical view but without the gripping member 14 to make the elements of the repositioning table 23 visible. In this illustrative example, the repositioning table 23 includes a carriage 24 which is movable in translation along two orthogonal rectilinear directions by means of a set of slides. The repositioning table 23 in this example thus consists of a conventional motorized Cartesian XY structure allowing the carriage 24 to be moved in the plane. The repositioning table 23 is part of the gripping member 14 and is here fixed directly on the pivot 25 of the mobile support 10 so that the rotation of the gripping member 14 around its axis A14 jointly drives the repositioning table 23 and the rest of the gripping member 14.Optionally, the gripping member 14 may also include an additional pivot 31 between the carriage 24 and the gripper 15, thus providing an optional additional axis of rotation.

[0113] Of course, any other solution allowing the gripper 15 to be moved in a plane intersecting and advantageously perpendicular to the axis of rotation A14 could also be used, for example a series Cartesian mechanism, a series mechanism with parallel rotating axes, a parallelogram, or a five-bar planar mechanism. Furthermore, the repositioning table 23 could have only one axis of translation, or conversely, three degrees of freedom in translation.

[0114] Furthermore, the curved motion guide 9 may also include such a repositioning table 26, as illustrated in [Fig. 14]. This repositioning table 26 is then arranged in a secant plane and advantageously perpendicular to the axis A3 of the base 3 (when the interface 5 is a rotating interface). The repositioning table 26 allows the position of the curved movement guide 9 to be adjusted along at least one direction in the said plane intersecting and advantageously perpendicular to the axis A3. The movement of the curved movement guide 9 in this plane can be along one or more axes, and rectilinear or curved.

[0115] In the example of [Fig. 14], the repositioning table 26 comprises a carriage 30 which is movable in translation along two orthogonal rectilinear directions by means of a set of slides. The repositioning table 26 in this example thus consists of a conventional motorized Cartesian XY structure allowing the carriage 30 to be moved in the plane. The repositioning table 26 is part of the curved motion guide 9 and is here fixed directly onto the base 3 so that its rotation about its axis A3 (when the interface 5 is a rotating interface) drives both the repositioning table 26 and the rest of the curved motion guide 9. Optionally, the curved motion guide 9 may also include an additional pivot 32 between the carriage 30 and the guiding means of the movable support 10 (the slide 12 in the illustrated example), thus providing an optional additional axis of rotation.

[0116] Of course, any other solution could be used for the repositioning table 26, such as, for example, a series Cartesian mechanism, a series mechanism with parallel rotating axes, a parallelogram, or a five-bar planar mechanism. The repositioning table 26 could also have only one axis of translation, or conversely, have three degrees of freedom in translation.

[0117] The gripper 1 may also include any control element such as one or more visual sensors, stroke and / or limit switch sensors, linear and / or angular positioning elements, etc., commonly used in robotics for the control of the various moving elements of the gripper 1. The gripper 1 includes, for example, a vision device 27 (2D or 3D camera, lidar, etc.) connected to a three-dimensional vision and positioning system, common in the field of robotics, and capable of calculating the configuration of the robot and / or the gripper with respect to the object to be grasped or grasped.

[0118] The gripper 1 which has just been described can be used in the manner indicated below.

[0119] The nut as grasped object 2, given as an example in the figures, is an example of an object whose grasping, reorientation, and use (here screwing) require a grasper 1 with qualities of dexterity.

[0120] The gripper 1 first grasps the object 2, even with random positioning, as illustrated in the example in [Fig. 10]. This grasping is optionally facilitated by rotary repositioning elements 19 or telescopic gripping fingers 15A, 15B.

[0121] Figures 1 or 2, for example, illustrate the object 2 in the gripper 1, after it has been grasped.

[0122] The object 2 is then reoriented, with the possibility of configuring the gripper 1 for example with the axis A14 of the grasping member 14 which forms an angle (for example perpendicular) with the axis A3 of the base 3 (case of [Fig.11], for example), or of configuring the gripper 1 for example with the axis A14 of the grasping member 14 parallel or coincident with the axis A3 of the base 3 (case of [Fig.3] or 5, for example).

[0123] In the case where the gripping member 14 has a rotating repositioning element 19, an additional axis of the gripped object can also be arranged parallel to, or coincide with, the axis A14 of the gripping member, or with the axis A3 of the base 3.

[0124] During the phases where the gripper 1 is configured with the axis A14 of the gripping member 14 aligned with the axis A3 of the base 3 (as illustrated in Figures 3 and 5), the rotation of the base 3 can be directly used to rotate the gripped object 2. In the example illustrated in [Fig. 16], the nut, after being reoriented, is screwed in this configuration.

[0125] Fig. 16 illustrates an example in which the robotic arm is used to screw nuts onto several faces of an industrial product under construction, and from several angles of attack.

[0126] In this configuration, the gripper takes advantage of the motorization of the interface 5 of the robotic arm 4, which is here a rotating interface that is generally powerful and can also be adapted for continuous rotation. When the two axes A3, A14 are aligned, the two associated motorizations can also act jointly, rotating both the base 3 and the gripping element 14, for example for faster screwing.

[0127] The gripping, reorientation, and power functions are thus advantageously decoupled with the gripper 1 which positions, and the robotic arm which enables screwing.

[0128] The robotic arm 4 equipped with the gripper 1 is implemented here in heterogeneous situations, where the dexterity of the gripper 1 is required. For example, [Fig. 17] schematically illustrates a situation subsequent to the operation of [Fig. 16], in which the robotic arm must screw on another nut in a location that does not allow the use of the configuration of [Fig. 16], due to an obstacle 29.

[0129] The gripper 1 is then reconfigured with the axis A14 of the grasping member 14 forming an angle with the axis A3 of the base 3 (as in Figures 2, 4, 11, for example). The robotic arm is then no longer used for the action on the grasped object 2 (the screwing in this example), but only to insert the gripper 1 between the obstacle 29 and the work area. Figure 17 illustrates a right angle between the two axes A3 and A14; however, the curved movement guide 9 allows for any other working angle.

[0130] Within the framework of the invention, the curved movement guide 9 has at least two functions: the reorientation of the grasped object 2, and the angular positioning of the axis A14 of the grasping member 14, when the latter is used for work on the grasped object (which can be the screwing of a nut as in the illustrated example, but also for example the positioning of a camera at a certain viewing angle).

[0131] Axis A3 (when interface 5 is a rotating interface) is therefore not used here for screwing, but only for positioning the gripped object, while axis A14 is used for screwing. The action on the gripped object 2 is then carried out with minimal movement, or with very little stress on the robotic arm 4.

[0132] In the illustrated example of screwing a nut, or any other helical element requiring translational support along the screwing axis, this support can be achieved by the robotic arm 4 itself, or by an internal element of the gripper 1 (telescopic elements of the gripping member 14, for example).

[0133] Fig. 18 illustrates an example where the grasped object 2 is a tool (a screwdriver, in the illustrated example) which can be grasped in this example by the grasping member 14 equipped with elastic cushions or vacuum pockets (i.e. flexible pockets capable of deforming to conform to the objects to be grasped and filled with a fine powder made up, for example, of coffee grounds or apricot kernel powder, connected to a device allowing a vacuum to be created in them, so as to compress and make almost rigid the powder filling these pockets, thus ensuring a firm grasp of the objects) 22. As previously explained, this screwdriver can be rotated either by the axis A3 of the base 3, or by the axis A14 of the grasping member 14, or even with these two axes A3, A14 in conjunction.

[0134] In the example illustrated in [Fig. 18], this screwdriver can be gripped in a random initial position, for example flat, and then used in another angular orientation.

[0135] These examples illustrate how the gripper 1, despite a complexity much lower than anthropomorphic prehensile hands, allows almost as many repositioning possibilities, and this with a more reliable grip, adapted to transmit more power, and presenting the reliability and cost required for industrial applications.

[0136] Figure 19 illustrates an additional possibility offered when the grasping member 14 can close asymmetrically. In this example, the grasping fingers 15A, 15B are both translationally mobile. independent on the base 17 of the clamp 15, so that a grasped object 2 can be translated on the base 17 along an axis perpendicular to the axis A14.

[0137] In the example illustrated in [Fig. 19], the grasped object 2 is an asymmetric screw, whose head and body are not coaxial. These screws are used in certain areas of industry for relatively rare specific needs and, in this example, represent a situation requiring complex means to automate production. In this example with interface 5, which is a rotating interface, the gripping member 14 will reposition the gripped object 2 using the gripper 15 so that the axis of rotation of the threaded part of the screw (and not that of the head of the screw) is coincident with the axis of rotation A14 of the gripping member 14. The gripper 1 will thus be able to screw this screw either by rotation around the axis A3 of the base 3 (having previously aligned the axis A14 with the axis A3 as in the configuration of [Fig. 16]), or with the axis A14 of the gripping member 14 (as in the configuration of [Fig. 17]).

[0138] Fig. 20 illustrates an additional possibility offered when the gripping member 14 includes a repositioning table 23. In this example, the repositioning table allows the gripper 15 to be offset relative to the axis A14 of rotation of the gripping member 14.

[0139] In the example illustrated in [Fig. 20], the grasped object 2 is an adjustable wrench, which must therefore be grasped by its handle, while the axis around which it must be rotated is located at the end of this handle. As before, this example illustrates a situation in which, in prior art, only a very complex anthropomorphic hand could use such a tool as a grasped object.

[0140] In this example, the repositioning table 23 will reposition the clamp 15 so that the axis of rotation of the screwing area (i.e. the axis of rotation of the nut when held in the wrench) is coaxial with the axis A14 of the gripping member 14. The gripper 1 will thus be able to screw a nut with the wrench as described above, either by rotation around the possible axis A3 of the base 3 (having previously aligned the axis A14 with the axis A3 as in the configuration of [Fig. 16]), or with the axis A14 of the gripping member 14 (as in the configuration of [Fig. 17]).

[0141] The invention thus enables the implementation of a gripper with a simple design and conventional construction elements in the field, and exhibiting significant dexterity qualities, capable of operations such as screwing screws or nuts in different configurations, without resorting to bulky and inflexible screw extensions, or of operations such as working with tools as grasped objects, and this in cluttered environments, in cavities, or in the presence of moving elements, with objects to be grasped presented in bulk, etc.

[0142] Various embodiments may be implemented. In particular, any known variant in the field of robotics may be implemented for the described translation and rotation axes, as well as the motorizations of these axes, their measurement means, their transmission means (linear or rotary motors, belt drives, motorized pivots, rack and pinion or toothed belt drives, etc.), and their control means.

[0143] The motorizations can thus be of any type commonly used in robotics, for example direct current motors (with or without an iron rotor), self-piloted synchronous motors (so-called "brushless"), pneumatic, hydraulic, thermal actuators, or even those using shape memory alloys, piezoelectric materials, or electro-active polymers, or any combination of these principles.These actuators, which can be used with any common type of reducer (e.g., gear, friction, belt, cable, ball screw, worm gear, or Harmonie Drive type, or any combination of these if they have multiple stages), can be positioned at the joints they drive, on the body immediately upstream or downstream of these joints, or they can be located further upstream or downstream of the gripper, using suitable transmission means (e.g., belts, cables, connecting rods, or other). These actuators can also be used in pairs at some or all joints (agonist and antagonist actuation), and they can be combined with elastic elements (linear or non-linear springs), arranged in series or parallel to the actuators, for measurement purposes (e.g.configuration of the type "series elastic actuators"), contributing to the forces of the actuators, or opposing them (e.g. return to neutral or reference position). Some joints may also be equipped with brakes, for example friction or powder brakes or based on the use of rheological fluids.

[0144] The measurement means may, for example, include linear or rotary joint position sensors (such as optical or magneto-optical encoders, Hall effect sensors, potentiometers, etc.), and / or force sensors (joint or arranged between interface 5 and the gripper, for example), and / or proximity sensors (for example, capacitive type) or tactile sensors, or one or more vision sensors (2D or 3D, in the visible or non-visible spectrum, multispectral or non-multispectral, integrated into the robot, the gripper, or any other element of the environment).

[0145] The control means can implement control modes based on position, force, impedance, or admittance, for example. These control means can be integrated into gripper-specific control units, or they can be integrated into the robot controller.

[0146] The illustrations are also simplified, particularly in their dimensioning, it being understood that the gripper 1 can be reinforced and dimensioned by all conventional means in mechanics, according to the forces and torques for which it is intended in the context of an application.

[0147] Furthermore, interface 5 can be a rotating interface, as in the illustrated examples, or a non-rotating interface. Axis A3 can then be represented by another pivot located elsewhere on the gripper. Thus, the gripper may not rotate around axis A3, with a non-rotating interface 5, and may only use the other degrees of freedom available to it, notably axis A14.

Claims

Demands

1. Reorientable robotic gripper (1) intended for a robotic arm (4) which has at least one degree of freedom and which further comprises at one of its ends a gripper attachment interface (5), this gripper (1) comprising a base (3) provided with a removable fixing device adapted to be mounted on the gripper attachment interface (5) of the robotic arm (4), the base (3) extending along an axis (A3) from the interface (5) of the robotic arm, this gripper (1) being adapted to grasp an object (2) and to modify the orientation of the grasped object with respect to the base (3), this gripper (1) being characterized in that it comprises: - a curved motion guide (9) carrying a movable support (10) which is adapted to describe a curved trajectory with respect to the base (3); - an object grasping device (14) mounted mobilely in rotation, around an axis of rotation (A14), on the mobile support (10).

2. Gripper according to claim 1, characterized in that the curved trajectory of the movable support (10) relative to the base (3) has at least one position in which the movable support (10) is positioned on the axis (A3) of the base (3).

3. Gripper according to claim 2, characterized in that the curved motion guide (9) is arranged so that the trajectory of the movable support (10) comprises: at least one position in which the axis of rotation (A14) of the object grasping member (14) is parallel to the axis (A3) of the base (3); and at least one position in which the axis of rotation (A14) of the object grasping member (14) forms an angle with the axis (A3) of the base (3).

4. Gripper according to claim 3, characterized in that the trajectory of the movable support (10) comprises: at least one position in which the axis of rotation (A14) of the object grasping member (14) coincides with the axis (A3) of the base (3); and at least one position in which the axis of rotation (A14) of the object grasping member (14) is concurrent with and forms an angle with the axis (A3) of the base (3).

5. A gripper according to any one of the preceding claims, characterized in that the curved motion guide (9) comprises a portion in an arc of a circle, the moving support thus presenting a portion of semi-circular trajectory.

6. Gripper according to any one of the preceding claims, characterized in that the trajectory of the movable support (10) has at least one position in which the axis of rotation (A 14) of the object grasping member (14) forms substantially a right angle with the axis (A3) of the base (3).

7. Gripper according to any one of the preceding claims, characterized in that the curved movement guide (9) comprises a curved slide (12), and in that the movable support (10) is formed of a slide engaged on this curved slide (12).

8. Gripper according to claim 7 when it depends on claim 2, characterized in that the curved movement guide (9) has an overhanging portion (13) such that said slide (12) has a portion arranged opposite the axis (A3) of the base (3).

9. Gripper according to any one of claims 1 to 6, characterized in that the curved motion guide (9) comprises at least two arms (9A, 9B) articulated by a pivot (11), one of the arms (9A) being fixed on the base (3), and another of the arms (9B) carrying the movable support (10) at its end, the movable support (10) then presenting a circular trajectory centered on said pivot (11).

10. Gripper according to claim 9, characterized in that at least one of said arms (9A, 9B) is curved.

11. Gripper according to any one of the preceding claims, characterized in that the curved motion guide (9) comprises a repositioning table (26) adapted to adjust its position in at least one direction in a plane intersecting the axis (A3) of the base (3).

12. Gripper according to claim 11, characterized in that said repositioning table (26) is adapted to adjust the position of the curved motion guide (9) in at least one direction in a plane perpendicular to the axis (A3) of the base (3).

13. Gripper according to claim 11 or 12, characterized in that the curved motion guide (9) has an additional axis of rotation (32) between said repositioning table (26) and the rest of the curved motion guide (9).

14. Gripper according to any one of the preceding claims, characterized in that a pivot (25) is mounted on the movable support (10), the object grasping member (14) being mounted on this pivot (25).

15. Gripper according to any one of the preceding claims, characterized in that the object grasping member (14) comprises a gripper (15) including a base (17) on which gripping fingers (15A, 15B, 15C) are mounted.

16. Gripper according to claim 15, characterized in that said gripping fingers (15A, 15B) are telescopic.

17. Gripper according to any one of claims 15 or 16, characterized in that said gripper (15) comprises two opposing gripping fingers (15A, 15B).

18. Gripper according to claim 17, characterized in that the two gripping fingers (15A, 15B) are adapted to grip on an axis asymmetrically with respect to the axis of rotation (A14) of the object grasping member (14).

19. Gripper according to any one of claims 15 to 18, characterized in that it comprises rotary repositioning elements (19) at the end of the gripping fingers (15A, 15B), adapted to rotate the grasped object around an axis substantially orthogonal to the axis of rotation (A14) of the object grasping member (14).

20. Gripper according to claim 19, characterized in that the rotary repositioning elements (19) comprise a clamping disc (20) mounted on each gripping finger (15A, 15B) by a pivot (21).

21. Gripper according to any one of the preceding claims, characterized in that the object grasping member (14) comprises a repositioning table (23) adapted to adjust its position in at least one direction in a plane intersecting the axis of rotation (A 14) of the object grasping member (14).

22. Gripper according to claim 21, characterized in that the repositioning table (23) is adapted to adjust the position of the object grasping member (14) in at least one direction in a plane perpendicular to the axis of rotation (A14) of the object grasping member (14).

23. A gripper according to claim 21 or 22, characterized in that the object-gripping member comprises an additional axis of rotation 24 between said repositioning table and the rest of the object capture device.

24. Gripper according to any one of the preceding claims, characterized in that it comprises a vision device (27) adapted to control the modification of the position and / or orientation of the grasped object relative to the base (3).

25. Gripper according to any one of the preceding claims, characterized in that the base (3) is a base rotating about its axis (A3).

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