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EP-4536446-B1 - UNDERACTUATED ROBOTIC HAND

EP4536446B1EP 4536446 B1EP4536446 B1EP 4536446B1EP-4536446-B1

Inventors

  • ZAPPATORE, Giovanni Antonio
  • LONGO, Alberto
  • DIMASTROGIOVANNI, Mauro
  • TINELLA, Domenico
  • ACCOGLI, Andrea

Dates

Publication Date
20260513
Application Date
20230612

Claims (15)

  1. Mechanism for moving the four aligned fingers (2, 3, 4, 5) of an anthropomorphic hand, comprising a motor (M1) and three differential stages configured to transmit motion from said motor (M1) to said aligned fingers (2, 3, 4, 5), wherein : - said differential stages are bevel gear differential stages, each comprising a train carrier (14, 24, 34) and two sun gears (15, 16, 25, 26, 35, 36); - said differential stages are arranged so that the axes of rotation of said train carriers (14, 15, 16) are aligned; - said motor (M1) is configured to move directly the train carrier (14, 24, 34) of one of said differential stages by means of a coupling between a worm screw (R1) on the motor and a crown on the train carrier (14, 24, 34) of one of said differential stages ; - said differential stages are configured so that at least one of the sun gears of said differential stage moved by the motor M1 is integral to the train carrier of a second differential stage adjacent thereto; - said differential stages are configured to move said four aligned fingers (2, 3, 4, 5) by means of four of said sun gears (15, 16, 25, 26, 35, 36); - the sun gear not engaged in the movement of said aligned fingers and not integral to the train carrier of said second differential stage is integral to the train carrier of said third differential stage characterised in that the differential stage moved by said motor (M1) is a lateral stage of said three aligned differential stages, and in that said lateral differential stage has a sun gear (26) integral to the train carrier (14) of the differential stage adjacent thereto and the other sun gear (25) configured to control the movement of the index finger of said anthropomorphic hand.
  2. Anthropomorphic robotic hand comprising a mechanism for moving the four aligned fingers (2, 3, 4, 5) according to claim 1
  3. Anthropomorphic robotic hand according to claim 2, further comprising a frame (00) and four aligned fingers, each comprising two phalanges and one appendix hinged to each other in pairs around a relative axis of rotation, said fingers being configured so that the appendixes of the fingers from index finger to ring finger are hinged to said frame (00) at the axis of rotation (260) relative to the movement of adduction-abduction of the appendix (23) with respect to the frame (00).
  4. Anthropomorphic robotic hand according to claim 3, characterized in that said three differential stages are contained inside a cylindrical recess suitably obtained in the frame (00), open only on one side to allow its introduction, and in that said hand comprises also a closing lid (C1) of said recess and in that between the differential train and the frame, inside the recess, it is provided a linear spring (300), said spring being configured so that it is compressed after translation of said three differential stages inside said cylindrical recess.
  5. Anthropomorphic robotic hand according to claim 4, characterized in that said lid (C1) is provided with a central hole and comprises a button (P1) which is free to translate along the axis of rotation of the differential train, configured so that a pressure on said button (P1) makes said three differential stages translate along their own axis, disengaging the sun gears (25), (26), (35), (36) respectively from the fingers (2), (3), (4) and (5) and compressing the spring (300).
  6. Anthropomorphic robotic hand according to one of claims 3 to 5, characterized in that it further comprises a plurality of elastic elements (214, 314, 414, 514) interposed between appendixes and frame in order to deaden potential blows received by said fingers (2,3,4 and 5).
  7. Anthropomorphic robotic hand according to one of claims 3 to 6, further comprising a palm and characterized in that it further comprises elastic elements (215, 315, 415, 515) interposed between the frame (00) and the appendixes, configured to deform elastically and to allow a translation of the appendixes with respect to the palm.
  8. Anthropomorphic robotic hand according to one of claims 3 to 7, characterized in that each of said fingers comprises a first toothed pulley (212) positioned at the axis of rotation (240) between proximal phalanx (22) and appendix (23), idle with respect to such axis of rotation, and a gear integral thereto (2024) engages with a transmission gear (213) idle with respect to the an axis of rotation (270) on the appendix (23) and configured to engage with a sun gear (25) of one of said differential stages, so that said sun gear can transmit the torque deriving from said motor (M1) to said transmission gear (213).
  9. Anthropomorphic robotic hand according to claim 8, characterized in that said first toothed pulleys of each of said aligned fingers (212, 312, 412, 512) are constituted by one toothed pulley, realized as a whole with the respective shaft (212, 312, 412 and 512), integrally mounted to a gear (2024), said gear being configured to engage with the relative transmission gear (213), said toothed pulley being connected by means of a toothed belt (211) to a following pulley (210), having axis of rotation (220) coincident with the relative axis of rotation between proximal phalanx (22) and distal phalanx (21).
  10. Anthropomorphic robotic hand according to one of claims 3 to 9, further comprising a finger corresponding to the thumb (I), a metacarpus and a relative actuation mechanism.
  11. Anthropomorphic robotic hand according to one of claims 3 to 10, further comprising a control electronic board configured to receive in input control signals by the user and to control said motor M1 as a function of said control signals.
  12. Anthropomorphic robotic hand according to one of claims 8 to 11, characterized in that the toothed pulleys coupling the various fingers to the frame are configured so that the index finger (2) is inclined of 5° to the middle finger (3), the ring finger (4) is inclined of 5° to the middle finger (3) but in the opposite direction to the index finger (2), and the little finger (5) is inclined of 10° to the middle finger (3) in the same direction of the ring finger (4).
  13. Anthropomorphic robotic hand according to one of claims 3 to 12, further comprising a plurality of gloves (29, 39, 49, 59) realized in elastic material, each configured to cover a respective finger from outside and integrally installed to the appendixes (23) of each finger, said gloves (29, 39, 49, 59) being installed so that when the appendix (23) is introduced in the frame (00), the glove (29) is compressed between the appendix (23) and an elastic collar (214) integral to the frame (00), thus sealing the whole mechanism on the frontal side.
  14. Anthropomorphic robotic hand according to one of claims 3 to 13, characterized in that the phalanges inside each finger are moved, each one with respect to the adjacent phalanx, by means of a train of idle gears, in odd number, with the first and the last gear of said train of gears positioned at the relative axis of rotation between phalanges, and the last gear of the train integral to the last phalanx.
  15. Anthropomorphic robotic hand according to one of claims 3 to 14, characterized in that said sun gears (15, 16, 25, 26, 35, 36) by means of which said differential stages move said four aligned fingers (2, 3, 4, 5) are spherical gears, and engage with the respective spherical gears (213), idle with respect to their own shaft, installed at said axis of rotation (270) on the appendix, the appendix (23) being also hinged to the frame at an axis of rotation (260) perpendicular to said axis of rotation (270).

Description

INTRODUCTION The present Patent application for industrial invention relates to an underactuated robotic hand which is highly robust, both in terms of capability to resist to outer stresses (compliance) and degree of resistance to the penetration of liquid and solid particles. In particular, the present application relates to a control mechanism of the four aligned fingers of an anthropomorphic hand. TECHNICAL FIELD The definition "robotic hand" refers to a device with anthropomorphic inspiration. The robotic hands proposed in literature can be divided in three main categories according to the number of their degrees of freedom (DOF) and of their degrees of actuation (DOA): fully actuated, underactuated and redundantly actuated. Fully actuated robotic hands have a number of degrees of freedom equal to the number of degrees of actuation. Underactuated robotic hands have a number of degrees of freedom higher than the number of degrees of actuation. Redundantly actuated robotic hands have a number of degrees of freedom lower than the number of degrees of actuation. Fully actuated robotic hands, while capable of efficient grasping, are extremely complex, and this leads to high costs and an overall lack of robustness. And this is especially true for redundantly actuated robotic hands. This is the main reason why, recently, the interest in the design of underactuated robotic hands has increased. The basic idea of the underactuation in the robotic grasping is to use a mechanic system that, by means of passive elements as springs and mechanical limits, can automatically adapt to the specific shape of the grasped object, so that the number of required actuators is lower than the number of DOF. This results in simpler control systems and in a reduction of the manipulator costs. One of the manners to obtain an underactuated mechanism is to use differential systems which automatically distribute an input to several outputs, the ratio between such outputs being defined by their kinematic state and by design parameters of the mechanism itself. In order to obtain more than two outputs, several differential modules can be used, configured in series or in parallel according to the needs, each one adding 1 DOF to the system. So, (n - 1) differential stages are generally needed to obtain n outputs. PRIOR ART In particular, at the state of the art, there are known underactuated robotic hands which use one or more differential stages to transmit motion to the various fingers. One example in described in document KR100848170. Another example is described in JP2001277175, wherein a robotic hand is described, whose kinematic scheme, extracted by said document, is shown in figure 0. Documents US 2020/047351, US 5 447 403, WO 2004/026540, US 2015/182353, CN 105 583 839, US 4 986 723 and CN 109 227 583 disclose examples of robotic multi-articulated fingers and of robotic hands with multi-articulated fingers comprising differential gears for the under-actuation of the hand. TECHNICAL PROBLEM Yet, it remains unsolved the problem to provide an underactuated robotic hand which allows a simple actuation of all the aligned fingers, which is structurally robust and which allows a simple replacement of the fingers, for example in case of failure, and adjustment of the mechanism of the same, and which is also highly resistant to mechanical stresses and to the penetration of liquids and powders, so that the need of maintenance interventions during the useful life of the device is reduced. Another technical problem, unsolved at the state of the art, is to provide a highly underactuated robotic hand, with a mechanism based on gears and toothed belts and without using unidirectional actuation means, such as tendons, so to have a highly repeatable behavior and so easily controllable by the user. Yet, another technical problem, solved by the present invention, is to provide an anthropomorphic hand with dimensions and weight comparable to the ones of a normal limb, by reducing the number of active components (motors) so to reduce the weight of the device and to increase its usability. Another problem solved by the hand according to the present invention is to provide an underactuated robotic hand, whose mechanism allows to imitate the human hand functionality as accurately as possible, and which allows in particular to distribute the tightening torque differently among the various fingers, as it occurs in a human hand. Finally, a technical problem solved by the present invention is to provide an underactuated robotic hand, whose fingers phalanges dimensions can be modified without needing a re-design of the mechanism and without modifying the grasping behavior of the device. BRIEF DESCRIPTION The present invention realizes the prefixed aims since it is a mechanism for moving the four aligned fingers (2, 3, 4, 5) of an anthropomorphic hand, comprising a motor (M1) and three differential stages configured to transmit motion from said motor (M1) to sai