Adaptive grasping finger for the surface of a solid sample of complex and varied shape.

Abstract

A mechanical gripper finger device adapts to the surface of a complex and varied solid sample. The invention relates to a gripper finger device that improves the chances of gripping a complex solid sample using a mechanical gripper. It consists of a frame (1); via pivot joints, the flexible connecting rod (2) and the rigid connecting rod (4) are attached. The pad (3) is pivotally connected to the connecting rods (2) and (4). The force transmission rod (5) is connected to the connecting rod (4) and to the linear actuator with axis (O). The movement of the connecting rod (4), generated by the connecting rod (5), brings the pad (3) into contact with the sample, causing compressional deformation of the flexible connecting rod (2) and influencing the distribution of the gripping force of the pad on the sample surface. Figure for the abbreviation: Figure 1

Description

Title of the invention: Adaptive gripping finger for the surface of a solid sample of complex and varied shape. Technical field of the invention

[0001] The present invention relates to a gripping finger with a deformable parallelogram architecture to adapt to the surfaces of a solid sample in order to maximize its gripping performance and minimize damage to the sample. This is particularly relevant for use in mechanical grippers for solid samples, e.g., three-finger grippers or two-finger grippers. Previous technique

[0002] The rigid parallelogram is traditionally used for its reliability and ease of implementation. This has the advantage of keeping the gripper pads of a gripper in the same orientation throughout the movement. However, this results in an inability to adapt to the surface of a sample, which reduces the contact area and the probability of gripping a solid sample with a complex and varied shape.

[0003] The use of the rigid parallelogram can damage fragile samples of a solid nature during gripping efforts due to the deformation intolerances of this type of mechanism.

[0004] The rigid parallelogram is a mechanical system which can prove to be too rigid, this can limit the system's ability to cope with shocks, vibrations or certain mechanical stresses. Technical solution

[0005] The device according to the invention overcomes these drawbacks. Indeed, the rigid parallelogram mechanism replaces the system's external rigid connecting rod with a flexible connecting rod acting like a spring. When a force is applied to the pad of the deformable parallelogram, the external connecting rod compresses, passively orienting the pad onto the surface of the solid sample and thus maximizing the contact area between the gripper pad and the sample. The orientation of the pad and the distribution of force on the surface of the solid sample increase the probability of successful gripping and significantly reduce the risk of damaging the solid sample. The flexible connecting rod also allows the gripper to withstand certain mechanical stresses such as shocks, vibrations, or mechanical strain, thereby improving its long-term durability.

[0006] The attached drawings illustrate the invention: Brief description of the figures

[0007] Fig. 1 represents, in side view, the architecture of the invention representing a finger of a 3-finger mechanical gripper.

[0008] Figure [Fig.2] represents, in isometric view, the adaptation of the fingers on a 2-finger mechanical gripper.

[0009] Fig. 3 represents, in isometric view, the adaptation of the fingers on a three-finger mechanical gripper.

[0010] With reference to these drawings, the device comprises a frame (1), to which are fixed the flexible connecting rod (2) and the rigid connecting rod (4). The pad (3) is connected by pivot joints to the connecting rods. The force transmission connecting rod (5) is connected by a pivot joint to the rigid connecting rod (4).

[0011] With reference to these drawings, the force transmission link (5) transmits a force enabling the finger to bend inwards or unfold outwards as shown in [Fig. 4]. Through contact with the solid object to be picked up and the force transmitted by the linear actuator (6) attached to the force transmission link (5), the flexible link (2) is compressed and acts on the orientation of the pad (3).

[0012] Fig. 4 represents the typical kinematics of the orientation of a finger that has been fitted onto a 3-finger mechanical gripper with the system of the invention.

[0013] Fig. 5 represents the typical kinematics from a video of the test of a prototype 3-finger gripper mainly produced by 3D printing. Description of the implementation methods

[0014] With reference to these drawings and according to the particular methods of embodiment and assembly: - The system's structure is similar to that of a rigid parallelogram. The external rigid link is replaced by a flexible link (2), capable of absorbing a compressive force like a spring. - All the parts of a finger are assembled on the same plane. - The base of the parallelogram is said to be constructed (1) and serves as a spatial reference. - The pad (3) is the part connecting the upper pivots of the rigid link (4) and the flexible link (2). - The initiation of the parallelogram's movement is generated by the force transmission link (5) attached to the rigid link (4) by a pivot joint. The force is transmitted by a linear actuator with axis (O, y) attached directly to the force transmission link (5) by a pivot joint, and thus drives the movement of the rest of the finger. - The pivots of these systems can be materialized by any type of mechanical element fulfilling the function of a pivot (e.g., bearing). - The initial inclination of the skate (3) of this system can be chosen by choosing an initial length of flexible link (2) different from that of the rigid link (4). - The flexible connecting rod (2) has an arc-shaped form allowing it to act like a spring. It is possible to change the rigidity characteristics of this connecting rod by modifying: its thickness, its radius of curvature. - The skate (3) has a mechanical stop whose role is to orient the skate orthogonally to the plane of the base of the frame (1) when the gripper is open to its maximum. - The flexible connecting rod (2) can be made by 3D printing by depositing materials layer by layer, by molding plastic material or by a metallic equivalent such as a spring tab.

[0015] The finger shown can be mounted on a 2-finger mechanical gripper as illustrated in [Fig. 2]. These fingers are oriented face to face with each other, having a plane of symmetry. The fingers are actuated by a single common linear actuator by means of a pivot joint connecting the force transmission rods (5) of each finger.

[0016] The finger shown can be mounted on a 3-finger mechanical gripper as illustrated in Figure 3, these fingers being oriented towards the center of the gripper along the central axis (O, y). The fingers are actuated by a single common linear actuator by means of a pivot joint connecting the force transmission rods (5) of each finger. List of reference signs:

[0017] 1: Building

[0018] 2: Flexible connecting rod

[0019] 3: Skate

[0020] 4: Rigid connecting rod

[0021] 5: Force transmission link

[0022] 6: Linear actuator

[0023] 7: Sample wall

Claims

Demands

1. A sample grasping finger (7) comprising a flexible link (2), a rigid link (4), a pad (3) connected to the flexible (2) and rigid (4) links by pivot joint, a force transmission link (5) connected by pivot joint to the rigid link (4), the flexible link (2) having an arc-shaped form enabling it to act as a spring.

2. Gripping finger according to claim 1, the flexible connecting rod (2) being formed by the 3D printing technique by layer-by-layer deposition of material, by molding of plastic material or by a metallic equivalent such as a spring tab.

3. Finger according to any one of the preceding claims, the initial length of the flexible link (2) being greater than the length of the rigid link (4) in order to slightly orient the pad towards the inside of the gripper.

4. A gripper comprising two or three fingers according to any one of the preceding claims, the gripper comprising a frame (1) on which the fingers are mounted by means of flexible (2), rigid (4) and force transmission (5) connecting rods, the fingers being actuated by a single common linear actuator (6) by means of a pivot linkage connecting the force transmission rods (5) of each finger.

5. Gripper according to the preceding claim, the pad (3) having a mechanical stop whose role is to orient the pad (3) orthogonally to the plane of the base of the frame (1) when the gripper is fully open.

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