Robot thumb and corresponding control method

Abstract

An anthropomorphic robot hand comprises: a frame (00); four aligned fingers and respective actuation means to rotate the fingers relative to the frame (00); a metacarpal bone (10) fixed to the frame (00) so as to be able to rotate and translate along an axis of rotation (180) of the cylindrical joint; a thumb (11) fixed to the metacarpal bone (10) so as to be rotatable along an axis (140) of the rotary joint; means for actuating the thumb (11) and the metacarpal bone (10); the invention relates to a device for actuating a thumb and a metacarpal bone, characterized in that the device for actuating the thumb and the metacarpal bone comprises: a first sub-mechanism actuated by a first motor (M2) integral with the thumb (11) and configured to move, by means of a worm (R2), a ring gear (T2) fixed so as to engage with corresponding teeth provided on the metacarpal bone (10), the rotation of the proximal phalanx relative to the metacarpal bone corresponds to the rotation of the ring gear (T2); a second sub-mechanism actuated by a second motor (M3) integral with the frame (00) and configured to move, by a worm (R3), a ring (T3) configured to rotate, by a clutch (C1), the metacarpal bone (10) relative to the axis (180) of the cylindrical joint.

Description

Technical Field

[0001] This industrial invention patent application relates to a thumb for a robotic hand, which has high strength and flexibility, and is characterized by active flexion and controllable rotation achieved through active and passive means by the user. Background Technology

[0002] In the hands of many robots known in the prior art, the thumb moves via the same motor that controls the other fingers. Generally, in these cases, there is a first differential stage with its two outputs connected to the thumb and the other fingers respectively. However, this embodiment somewhat restricts the movement of the thumb to the movement of the other fingers and does not allow for all advantageous movement configurations. For example, it is impossible to open the thumb while clenching the other fingers, or vice versa. In other embodiments, the thumb is moved by a dedicated motor, thus involving a kinematically independent mechanism relative to the mechanism of the four aligned fingers.

[0003] In any case, the mechanism of the thumb should be able to: allow the metacarpals to rotate to move the thumb closer to or away from the metacarpals, and allow the two phalanges of the thumb to extend and clench. It also needs to coordinate with the four aligned fingers to control the thumb, including its position and the speed of extension and clenching, to provide the various grasping motions typically performed by the human hand.

[0004] Document EP2125091 provides the first solution to this control problem, which describes an anthropomorphic hand equipped with an EMG sensor and a sensor that measures the angle between the thumb and palm. The device configuration described in EP2125091 moves the fingers of the hand based on signals detected by the EMG device and signals emitted by the sensor measuring the angle between the thumb and palm, and blocks the movement of one or more fingers to obtain the desired configuration.

[0005] However, the problem of providing a thumb for a robot's hand remains unsolved, in order to overcome the limitations associated with the prior art and, in particular, to allow rotational movements to be performed actively by a motor controlled by sensor signals that detect the user's physiological parameters, and passively by the user's own contralateral limb, while being robust, compact, and allowing for easy replacement, such as in the event of a malfunction.

[0006] Another technical problem that remains unsolved in the existing technology is to provide a robotic thumb that patients can easily control all the movements they want to perform without having to choose different grips through complex muscle contractions.

[0007] However, the remaining technical problem is to provide a method for controlling a robotic hand that allows users to easily and immediately perform all possible grasping actions that a human hand can perform, based on physiological signals (EMG) detected on the user and the position of the hand itself.

[0008] More specifically, the problem of providing a robotic thumb that achieves the above objectives and exhibits excellent resistance to mechanical stress, liquid and powder penetration, thereby reducing the need for maintenance interventions during the service life of the equipment, remains unresolved.

[0009] However, the unresolved issue remains the provision of a prosthetic hand whose elastic elements can be adjusted without disassembling the device. In practice, for known devices, this prevents orthopedic technicians from performing fine-tuning to adapt its functionality to each individual user's preferences. Summary of the Invention

[0010] This invention achieves a predetermined objective because it is an anthropomorphic robotic hand comprising: a frame (00); a metacarpal bone (10) fixed to the frame (00) for rotation and translation along a rotation axis (180) of a cylindrical joint; a thumb (11) fixed to the metacarpal bone (10) for rotation along an axis (140) of the rotation joint; actuators for the thumb (11) and the metacarpal bone (10); at least two fingers fixed to the frame and corresponding actuators for driving the fingers, the fingers being oriented opposite to the thumb; characterized in that the actuators for the thumb and the metacarpal bone comprise: a first motor integrally formed with the thumb (11) A first submechanism actuated by a worm gear (R2) and configured to move a gear ring (T2) via a worm (R2), the gear ring being fixed to engage with corresponding teeth provided on the metacarpal (10), such that rotation of the proximal phalanx relative to the metacarpal corresponds to rotation of the gear ring (T2); a second submechanism actuated by a second motor (M3) integrated with the frame (00) and configured to move a ring (T3) via a worm gear (R3), the ring being configured to rotate the metacarpal (10) relative to the axis of rotation (180) of the cylindrical joint via a clutch (C1). Attached Figure Description

[0011] Figure 1 , 2 Figures 3 and 4 illustrate the kinematic scheme of the prosthesis according to the invention, with related nomenclature;

[0012] Figure 4 Two overall views of an uncovered prosthesis fitted with a thumb device according to the invention are shown from the back of the hand and the palm.

[0013] Figure 5 The kinematic scheme of the thumb and metacarpal bones used in the prosthesis according to the invention is shown;

[0014] Figure 6 An actuation sub-mechanism of the thumb actuated by a first motor is shown;

[0015] Figure 7 , 8 Figures 9 and 1 show various views of the submechanics of the metacarpal bone actuated by the second motor;

[0016] Figure 10 It shows three positions the thumb can take relative to the palm;

[0017] Figures 11 to 14 A schematic diagram illustrating the function of the Hall effect sensor equipped in the device according to the present invention is shown;

[0018] Figure 15 Some views are shown illustrating the implementation of the frame, thumb, and glove for covering the thumb according to the present invention;

[0019] Figure 16 Some exemplary views are shown, illustrating various possible grips using the device according to the invention. Detailed Implementation

[0020] As shown in the attached figures, and this does not limit the purpose of the invention, the prosthetic hand according to the invention comprises four fingers, corresponding to the index finger (II), middle finger (III), ring finger (IV), and little finger (V) of the human hand. Each finger includes the middle and distal phalanges (mp for the index finger, middle finger, ring finger, and little finger, respectively). II mp III mp IV and mp V ), proximal phalanges (pp for index, middle, ring, and little fingers respectively) II pp III pp IV and pp V ), and accessories (ap for index finger, middle finger, ring finger and little finger respectively) II ,ap III ,ap IV and AP V ).

[0021] The distal and proximal phalanges pass through the interphalangeal joints (IP) (IP for the index, middle, ring, and little fingers, respectively). II IP III IP IV and IP V The proximal phalanges are fixed together, and the metacarpophalangeal joints (MCPs for the index, middle, ring, and little fingers, respectively) are connected. II MCP III MCP IV and MCP VThe first of the two rotation axes is fixed to the appendage in the flexion-extension plane; then the appendage is fixed to the frame (00) representing the palm in the abduction-adduction plane via the second of the two rotation axes of the same metacarpophalangeal joint.

[0022] It should be noted that each finger can also have two phalanges, for example, to make very small hands, for which it is technically impossible or inconvenient to construct a device with three phalanges.

[0023] As can be seen in the attached diagram—for example, see [link to diagram]. Figure 1 —The prosthesis according to the invention also includes a finger corresponding to the thumb (I), the finger being formed by the proximal and distal phalanges (pp I Composed of, via the metacarpophalangeal joints (MCP) I ) fixed to the metacarpal (mc I The metacarpals are further connected by trapezoidal metacarpal joints (TM). I ) is fixed to the frame (00).

[0024] Furthermore, preferably, the hand according to the invention comprises four fingers corresponding to the index finger (II), middle finger (III), ring finger (IV), and little finger (V) of a human hand, and respective implementing means. In particular, the index and middle fingers are configured to be opposite the thumb (I) to perform various grasping actions required in daily life activities.

[0025] In the embodiments described below, the device has two degrees of freedom, determined by variables. This indicates that it refers to the first [number] of the thumb (I). The rotation of each joint (j=1 represents the trapezoidal metacarpophalangeal joint TM; j=2 represents the metacarpophalangeal joint MCP); the superscript k indicates the angle involved in the movement; flexion-extension angle (k=X) or abduction-adduction angle (k=Z). In these two degrees of freedom:

[0026] One of the degrees of freedom can be achieved by the proximal phalanx (pp) I The first motor (M2) within the unit is actively and bidirectionally controlled, corresponding to... Figure 7 The rotary joint shown by reference numeral (140) in the attached figure Obtained joint MCP I Flexion-extension movements;

[0027] Another degree of freedom can be actively and bidirectionally controlled by a second motor (M3) located in the palm (00), corresponding to... Figure 7 The cylindrical joint shown by reference numeral (180) in the attached figure. Permissible rotation to obtain trapezoidal metacarpal joint (TM) IThe abduction-adduction movement of the metacarpals; the cylindrical joint (180) also allows for vertical translation, which allows the metacarpals to be temporarily decoupled from the second motor (M3), thus allowing passive rotation relative to the user's contralateral limb. The degree of freedom.

[0028] Conveniently, the device according to the invention also includes a control electronic board configured to receive input control signals (preferably, but not limited to, via electromyography sensors) and control the equipped motor as a function of the control signals.

[0029] Furthermore, preferably, the control electronics are configured to receive input signals from all other sensors that may be equipped on the device, such as IMU sensors and position sensors, the functions of which will be explained below.

[0030] It should be noted that a rotary joint refers to a hinge coupling, which only allows relative rotation between two related elements and prevents relative translation, while a cylindrical joint refers to a coupling that allows relative rotation and relative translation along the axis of rotation.

[0031] In addition, it is equipped with two elastic elements (1111 and 1122), which are inserted into the trapezoidal metacarpal joint (TM). I The relative rotation between the two elements allows for small-angle rotation along two axes perpendicular to the joint axis to cushion potential impacts on the thumb (one of these rotations corresponds to an additional degree of freedom in the human hand). .

[0032] The frame is then preferably covered by a cover (01) to protect the device and the internal electronic board and to improve the appearance of the prosthesis so that it is as similar as possible to a human hand.

[0033] Due to the complexity of the device, it is deemed necessary to introduce a designated naming convention. The proximal and distal phalanges of the thumb are indicated by reference numeral (11), and the metacarpals by numerical reference numeral (10). The axis of rotation x of the thumb between the proximal phalanges and metacarpals (flexion / extension) is indicated by (140), while the axis of rotation of the metacarpals relative to the palm is indicated by (180). A preferred embodiment of the device is now described, with its kinematic scheme as follows: Figure 3 As shown.

[0034] It should be noted that, Figure 3 The right hand is shown as viewed from the back of the hand. Clearly, the same device can be implemented for the left hand. In the illustrated embodiment, the function of the anthropomorphic robotic hand is reproduced, equipped with four substantially aligned fingers, from the index finger to the little finger, and one opposing finger (thumb).

[0035] It should be noted that in this patent, "aligned fingers" refers to the fingers opposite the thumb, corresponding in the human hand to the index, middle, ring, and little fingers. It should also be noted that even though the device is described and shown with reference to four aligned fingers, the same device can be made with only two aligned fingers, or with four aligned fingers, where only two fingers are movable and the others are fixed, without departing from the purpose of the invention. In this way, a device with lower implementation cost is obtained, while the function of the metacarpals and thumb is no different from the function described and claimed herein.

[0036] The actuation mechanism for the thumb and metacarpals consists of two main submechanisms, each actuated by a different motor (M2, M3), or, for the second submechanism only, by the user's contralateral limb (e.g., the left limb, in the case of a prosthesis used for the right hand).

[0037] like Figure 6 As shown, the proximal phalanx (11) of the thumb is composed of a metal element (112) integral with a plastic cover (111). A motor (M2) is contained inside the proximal phalanx (11) of the thumb, and the motor housing is integral with the metal element (112).

[0038] The metacarpal (10) is conveniently composed of two sub-elements (101 and 102). The first sub-element (101) is fixed to the frame (00) at the axis of rotation (180) via a cylindrical joint, and the second sub-element (102) is fixed to the element (112) of the proximal phalanx (11) of the thumb at the axis of rotation (140) via a rotary joint. The two sub-elements (101) and (102) are integrally formed by a prismatic coupling, which is locked in place by bolts at the axis (160).

[0039] At the axis of rotation (140) between the element (102) of the metacarpal (10) and the element (112) of the proximal phalanx (11) of the thumb, and inside the element (112), a toothed ring (T2) is provided that idles along the axis of rotation (140) between the two elements. On one side of the toothed ring (T2), teeth are provided that mesh with multiple teeth on the second element (102) of the metacarpal (10). On the other side of the toothed ring (T2), a Bainstein washer (S1) is correspondingly provided between the toothed ring and the element (102).

[0040] The motor (M2) engages with the gear ring (T2) via a worm gear (R2), so that the proximal phalanx (11) of the thumb rotates relative to the metacarpal bone (10) about the axis of rotation (140) between a first position and a second position. In a preferred embodiment, the maximum permissible rotation between the first and second positions is 55°.

[0041] When the thumb contacts an object or is positioned at the thumb stop block, the movement of the proximal phalanx ceases, forcing the motor (M2) to stop. By controlling the motor current, the maximum applied torque is determined, thereby determining the maximum torque transmitted to the thumb that determines the gripping force. The speed of the gripping action can also be controlled by controlling the motor speed via the encoder (E2).

[0042] If the thumb is subjected to unexpected external stress, the Bassian washer (S1) is compressed, thereby allowing the toothed ring (T2) to translate along the axis of rotation (140), temporarily disengaging from the second element (102) of the metacarpal bone. In this way, the thumb rotates freely, absorbing the external stress, and thus its components are not damaged. The rigidity of the spring (S1) and the well-defined profiles of the teeth on the toothed ring (T2) and the second element (102) of the metacarpal bone ensure that the torque required to achieve this disengagement is higher than the torque applied by the motor (M2) to rotate the thumb (11), and lower than the torque that would damage the thumb components.

[0043] Therefore, in this way, the components are protected from unintended stresses that tend to flex or extend the thumb relative to the metacarpals, thus increasing the flexibility of the device and creating a "buffer zone" between the thumb and metacarpals, which guarantees a longer lifespan for the components used. Such measures are lacking in patents such as WO2021250233A1 and WO2022038506A1, while WO2020065266A1 uses a foldable rod-based system that allows the thumb to forcefully clench under external stress without damaging the device, but does not protect the thumb under stresses that tend to extend it. Therefore, such devices are more prone to breakage under external stress, which is the most common cause of breakage in such devices. In contrast, US11351042B2 provides one or more configurations in which the thumb includes a coupling system designed to protect the thumb from such uncontrolled stresses. This coupling system includes a driven element, a locking element, and a compression element, as in the case of this patent, but the substantial difference lies in the complexity of the structure. Specifically, the device according to the invention is characterized by its simple structure because it comprises very few components, unlike known devices which have many components, making the assembly more expensive and increasing the risk of system failure due to component breakage. For example, in cases where disassembly is required to replace components: in the device according to the invention, the components configuring the system can be accessed simply by removing the shaft provided at axis (180); in the case of US11351042B2, all components constituting the joint need to be removed from their respective positions. Components 103 and 104, integrated with the metacarpals, protect the device from external impacts.

[0044] Preferably, the thumb phalanx includes a pressure sensor at the fingertip, which is used to control the thumb motor and the behavior of other fingers.

[0045] In particular, because patients using prostheses lack clear proprioception of their limbs and when a grasp of an object is stable, the following situation may occur. For example, if a glass is grasped through the prosthesis and water is subsequently poured into it, as the amount of water in the glass increases (and therefore its weight increases), the prosthesis may not have enough strength to hold the glass, causing it to slip and fall. The function of the pressure sensor is to determine whether this occurs. To this end, the pressure sensor is configured to measure the pressure set between the fingertip and the grasped object, and the control board is configured to increase the applied torque when a decrease in pressure is detected. Therefore, if the object slips and the sensor measures a decrease in pressure, the device automatically closes without the patient's active control.

[0046] Specifically, the control board is configured to continuously detect the pressure applied by the fingertips on the object after a grasping action, and if this pressure decreases and the patient does not perform the action of opening the device, the control hand increases the gripping force until the sensor measures again the pressure value at least equal to the pressure value measured before the unexpected decrease in pressure.

[0047] like Figure 7 As shown, the motor (M3) is fixed to the frame (00) and engages with the ring (T3) via a worm gear (R3). This ring (T3) has teeth on its side surface that mesh with corresponding teeth on the side surface of the clutch (C1), which can rotate freely on the same axis of rotation (180). As shown in Figure (7), the clutch (C1) has holes along its entire periphery, the axes of which are parallel to the axis of rotation of the clutch itself, and are preferably, but not limited to, spaced apart from each other at 45°, wherein pins (P1) from the metacarpals (10) engage in the holes, thereby making the two components a single unit during rotation along the axis of rotation (180).

[0048] The metacarpal (10) is fixed to an axis integral with the frame at the axis of rotation (180) by two cylindrical joints. Between the axis and the metacarpal, at these two hinges, elastic cylinders (1111 and 1122) are introduced, which allow small-angle rotation in two planes perpendicular to the joint plane to cushion potential impacts to the thumb.

[0049] Therefore, motor M3 can rotate the ring (T3), which in turn rotates the clutch (C1), causing the metacarpal (00) to rotate around the axis (180). In this way, the thumb moves from a lateral position to a position opposite to the other fingers, and vice versa. Furthermore, in this configuration, the device cannot be reversed, so the worm gear prevents the thumb from rotating due to external stress, thus making the grip very secure.

[0050] Some known upper limb prostheses in the prior art have implemented devices that attempt to perform the same functions, such as the device described in US2018036145A1. However, the device is sometimes difficult to control: in fact, the user must be able to control finger flexion and thumb rotation, and since the user usually only has two control inputs (two surface electromyography sensors), the user uses two control inputs to achieve the "opening" and "clenching" movements of the fingers. In order to also be able to control rotational movements, the user is forced to perform complex muscle contraction patterns, which makes the control usually unintuitive and the learning time long.

[0051] Other devices on the market allow users to passively rotate their thumb, using the contralateral limb or an external opposing surface. However, to make the passive rotation of the thumb less strenuous and uncomfortable, such systems use friction-based or partially meshed devices between the metacarpals and the frame, which do not securely hold the components in place. Therefore, these devices are often subjected to involuntary actuation by unexpected external stresses, resulting in unintended thumb rotation and a less secure and reliable grip in everyday life.

[0052] The device described in WO2020065261 allows for active rotation via muscle control and “pseudo” passive rotation via a button located near the thumb, which the user can actuate with the contralateral limb, thereby causing motor actuation. However, this device does not allow thumb rotation when the hand is not powered, nor does it allow the metacarpal to be positioned in the intermediate position between two limiting blocks corresponding to the lateral position of the thumb (0°) and the thumb-index-little finger opposition (90°). In the case of the device according to the invention, instead, the user can disengage the metacarpal (10) from the clutch (C1) by vertically translating the metacarpal (10) upwards, thereby disengaging the pin (P1) of the metacarpal (10) from the hole of the clutch (C1) it engages. At this time, while keeping the metacarpal (10) raised, the user can rotate the pin 45° or 90° and then release it. A linear spring (110) located between the metacarpal and the frame brings the metacarpal back to the position, causing the pin (P1) to re-engage in the newly selected hole of the clutch (C1).

[0053] To make the operation easier, the hole on the clutch (C1) has a flared opening on the part facing the metacarpal bone to guide the pin (P1) of the metacarpal bone (10) toward the hole, even if the user does not perform the release at exactly the same time.

[0054] The rotation limit block is achieved by protrusions on the frame and metacarpals, which limit the maximum relative rotation between the two elements to 90°.

[0055] Therefore, the device just described overcomes the limitations of existing systems on the market, allowing for active and continuous thumb rotation via a motor (M3) and passive and intermittent thumb rotation via the user's contralateral limb in steps determined by the angular distance of a hole provided along the entire circumference of the clutch (C1), thus allowing for both high ease of use and a secure grip. This movement can also be achieved when the prosthesis is not powered, thereby increasing safety in dangerous situations requiring the release of the grip.

[0056] Furthermore, a Bass van der Wafer (S2) is provided between the clutch (C1) and the frame. When the thumb is subjected to high rotational stress, this spring is compressed, allowing the clutch (C1) to translate upward along the axis (180), disengaging the clutch from the ring (T3). In this way, the metacarpal bone rotates freely, absorbing external stress, and thus the components of the thumb are not damaged. The stiffness of the spring (S2) and the profile of the teeth on the ring (T3) and the clutch (C1) are precisely fixed so that the torque required to achieve disengagement is higher than the torque exerted by the motor (M3) rotating the metacarpal bone (10) and lower than the torque that would damage the thumb components.

[0057] A second Bass washer (S3) is also provided between the metacarpal and the frame, which functions to absorb impacts that tend to push the metacarpal (10) downward. For impacts that tend to push the metacarpal (10) upward, the same function is performed by a linear spring (110).

[0058] Therefore, in this way, the components are protected from unintended stresses that tend to translate the thumb upwards or downwards, as well as stresses that tend to rotate it inwards or outwards from the palm, thus increasing the flexibility of the device and creating a "buffer zone" between the thumb and palm, ensuring a longer lifespan for the components used. Patents such as WO2021250233 and WO2022038506A1 lack such measures and do not protect the thumb from stresses that tend to rotate the metacarpals inwards or outwards from the palm and move them upwards or downwards. The system provided in US11351042B2 instead primarily assigns the function of absorbing such stresses to the material used for user support, which is capable of elastic deformation. Therefore, under downward or upward impact, the support tends to rotate, and the actuator rotates accordingly, with the actuation device having two locking surfaces, one on the back of the hand and the other on the thumb, interlocking to prevent the other from rotating relative to it. Conversely, in the device according to the invention, the elements that absorb the impact that tends to rotate the thumb are a linear spring (110) and a Bavarian washer (S3), and the actuator support (and therefore the actuator itself) is not subjected to rotation after external stress because such support is fixed, as it is formed by the flange of the frame (00). Thus, the actuator does not have to directly follow the direction of the external stress, thereby achieving stability and less direct exposure to stress.

[0059] DE102021132277B3 also provides a system for protecting the thumb from external stress; however, it differs substantially in mechanical structure from the device aimed at the present invention: in this patent, there is no support designed to support the joint element, but rather the frame (00) itself is equipped with... Figure 7 The flanges shown (08, upper, and 09, lower) perform this function. Furthermore, for transmitting motion and imparting torsional rigidity, no other elements with external and / or internal teeth are needed, because it is the same pin that prevents the rotation of the metacarpal, acts as a connector on the upper part of the metacarpal, and thus rotates the thumb. This pin is made of a sufficiently rigid material and designed to perform this function.

[0060] When the metacarpal (10) comes into contact with the object being grasped (or reaches the limit block), the motor (M3) is forced to stop.

[0061] By controlling the motor current, the maximum applied torque is determined, thereby determining the maximum torque transmitted to the metacarpals that determines the gripping force. The motor speed can also be controlled via an encoder (E3) to control the speed of metacarpal movement and gripping force.

[0062] In the device according to the invention, the abduction-adduction axis (180) of the trapezoidal metacarpal joint is not required to be parallel to the axis of the forearm, as... Figure 4 As shown, however, it can be tilted relative to the axis of the forearm, with the aim of making the prosthesis more similar to a human hand. This tilt can be configured along the sagittal and coronal planes. This tilt is achieved by rotating the connecting flanges (08 and 09) from the frame (00) to the metacarpal (10) in two directions, respectively, by angles. and ( Figure 8 Therefore, the axis (180) of the metacarpal bone is first inclined along angle α, and then along angle α. The flanges of frame (00) are similarly tilted, becoming (08') and (09') respectively. This results in two parallel flanges, allowing for the assembly of the metacarpals, and thus the thumb, while maintaining the geometry of these components. In this way, the only component requiring modification is frame (99). Figure 9 .

[0063] In fact, unlike what happened in patent 102016000120646, this variant can be set up without modifying any components except the frame (00), which greatly simplifies the construction of other device variants.

[0064] In the case of the two submechanisms described, the use of a reduction unit with a worm gear, in addition to being equipped with a very compact way to perform deceleration and increase motor torque, is also an irreversible device: by acting on the thumb and metacarpal bones, this element cannot be re-extended because it is impossible to transmit the motion from the rings (R2, R3) to the motors (M2) and (M3) respectively.

[0065] Once the thumb and metacarpals are fully clenched, the motor can be turned off (thus saving battery power) because the grip remains stable regardless, as the fingers cannot be passively re-extended unless a possible safety device is used in a dangerous situation.

[0066] Furthermore, grip strength can be controlled by adjusting the motor current, which can be easily accomplished in several ways.

[0067] For example, the current can be controlled as a function of the number of signals read by the control electrode within a certain time interval (e.g., 1 signal per second for soft grip, 2 signals per second for medium grip, and 3 signals per second for strong grip).

[0068] Alternatively, the current drawn by the motor (and therefore the torque applied by the same motor, which determines the gripping force) can be controlled as a function of the signal strength detected by the electrodes, either in a direct proportional manner or in relation to it according to other calibration laws to be defined.

[0069] The compactness of the device allows the control panel (100) to also be placed inside the robot arm, such as Figure 4 As shown, the robotic arm thus achieves another level of modularity. This is particularly useful when it must be used by subjects with different levels of amputation: for example, for transradial amputations, a “wrist” or “forearm” module can be added to the robotic arm module, while for subwrist amputations, the robotic arm module can be used alone.

[0070] As is clearly understood from the previous description of the device, the function is completely similar for both the clenching and opening movements of the hand. In fact, all the connecting parts used are bidirectional (gears), and unidirectional elements (tendons, tension rods, etc.) are not used, as unidirectional elements have limitations in applying large forces and have greater internal friction.

[0071] Furthermore, because the device is isotropic due to its dedicated use of gear transmission, the gears apply a constant force regardless of the kinematic position of the fingers, thus ensuring constant performance throughout the workspace.

[0072] It is clear that the kinematic schemes shown are exemplary and do not limit the purpose of the invention. It should be noted that, for example, the size of the limb can be modified by changing the module or number of teeth of the gears or the size of the motor as needed.

[0073] As previously described, the device according to the invention allows for both active and passive rotation of the metacarpals relative to the palm. In particular, while the active rotation is continuous, the passive rotation allows the thumb to be positioned in three positions, such as... Figure 10 As shown:

[0074] - Lateral position (c), the thumb and palm are basically coplanar;

[0075] - Three-finger position (a): The thumb is opposite the index and middle fingers, thus forming an angle of about 90° with respect to the palm;

[0076] - Neutral position (b), between the two.

[0077] The device is configured to coordinate the clenching motion of the fingers and thumb via a control panel (100) to achieve all the major grips required in daily life.

[0078] Preferably, the device actually includes an inertial unit configured to acquire the orientation angle of the robotic hand relative to the horizontal direction, and configured to perform the following grasping based on signals detected by the electromyography sensor, the thumb position sensor, and the inertial unit:

[0079] 1- Three-finger grasp ( Figure 16-1 When the thumb is in the three-finger position, the tip of the thumb is pressed against the tips of the index and middle fingers, forming a clenched grip. This grip is ideal for grasping small objects.

[0080] 2- When the thumb and hand are configured similarly, but if the object being grasped is large, a strong grip is automatically performed. Figure 16-2 In this case, the fourth and fifth fingers of the robot hand also come into contact with the object being grasped.

[0081] 3- When the thumb is in the three-finger position and the hand is pointing downwards (between -80° and -90° relative to the horizontal) or upwards (between +80° and +90° relative to the horizontal), the thumb clenches behind the other fingers, locking the index and middle fingers in place. This creates a strong hook-like grip, which is useful for heavy objects if the hand is pointing downwards. Figure 16-3 (or, if the hand is facing upwards, it is used to grasp, for example, a handle on a bus.)

[0082] 4- "Handshake" grasping ( Figure 16-4 When the thumb is in a neutral position and the hand is at an interval between +90° and -80° relative to the horizontal plane, all fingers naturally clench together, creating an ideal grip for handshakes and similar actions.

[0083] 5- Typing grip ( Figure 16-5When the thumb is in a neutral position and the hand is pointing downwards (between -80° and -90° relative to the horizontal plane), the thumb clenches in front of the other fingers and rests against the side of the middle finger, thus providing a support base for the index finger, which can be used for typing on a keyboard.

[0084] 6- Lateral grip ( Figure 16-6 When the thumb is in a lateral position and the hand is fully clenched, the extension and clenching movements only control the extension and clenching of the thumb, without involving the other fingers, which thus provide stable support for keys, credit cards, or smartphones. To regain full control of the hand, the thumb needs to be fully extended again.

[0085] 7-Rest position ( Figure 16-7 (After fully extending your arms for 3 seconds, they will automatically move into a more natural and relaxed position.)

[0086] The various grip actuation angle values ​​can be modified by orthopedic technicians via hand-to-hand connection to appropriate software. This software also allows for the activation and deactivation of the described functions, providing patients with maximum personalization of the device's functionality.

[0087]

[0088] According to a preferred embodiment, the prosthetic hand according to the invention includes a thumb actuation device of the type described above and is equipped with a control system configured to prevent the user from performing complex muscle contraction patterns to perform all the main types of grasping required in a standard day.

[0089] Reference Appendix Figures 11 to 14 It should be noted that, according to a preferred embodiment, the device according to the present invention includes a thumb position sensor capable of determining the rotation angle of the metacarpal bone relative to the frame.

[0090] Specifically, the thumb position sensor includes: a Hall effect sensor (001) integrated with the frame (00) and two magnets (1001, 1002) integrated with the metacarpal bone (10).

[0091] The Hall effect sensor is equipped with two outputs: the first output is activated when a magnetic field is detected "outward" from the magnet that generates the magnetic field, and the second output is activated when the sensor detects a magnetic field entering "inward" from the magnet that generates the magnetic field.

[0092] The sensor detects changes in the magnetic field and generates a low logic level on the corresponding pin. Therefore, when a magnetic field is present, the sensor sets the pin to a low logic level, and when the magnetic field ceases to act, the corresponding pin is brought back to a high logic level.

[0093] By positioning two magnets (1001, 1002) on the metacarpal bone, oriented in opposite directions, two magnetic fields with opposite directions are generated, and three positions can be determined.

[0094] Two magnets are oriented in opposite directions, thus generating two magnetic fields in opposite directions.

[0095] Based on the position of the thumb relative to the palm, such as Figure 12 , 13 As shown in Figure 14, the two outputs of the Hall effect sensor can be: the first output is in a low logic state and the second output is in a high logic state, in which case the sensor will recognize a 90° rotation relative to the palm; both outputs are in a high logic state, in which case the sensor will recognize a 45° rotation relative to the palm; and the first output is in a high logic state and the second output is in a low logic state, in which case the sensor will recognize a 0° rotation relative to the palm.

[0096] Given that the presence of inertial sensors is known in the prior art, such as those described in EP2125091 or DE102021132277, the type of grip can be determined not only based on the thumb position but also on the hand orientation, thereby enabling the robotic hand to perform actions that are more similar to those performed by a human hand.

[0097] It should also be noted that the shaft at axis (160) is conveniently made of bolts, which can be tightened and loosened without removing other components of the hand, thus allowing for easy removal and replacement of the thumb in the event of breakage.

[0098] Upper limb prostheses are typically not designed for direct on-site repair by orthopedic technicians due to their highly complex design. Therefore, orthopedic technicians must send the device to the manufacturer's headquarters for any malfunction repairs, resulting in long wait times for users, high costs for manufacturers, and forcing manufacturers to send temporary replacement devices to users during the repair process. The few prostheses equipped with replaceable fingers often not only do not allow for thumb replacement but are also not waterproof because designing a reusable seal that functions between the finger and hand after finger removal and replacement by orthopedic technicians is technically very difficult.

[0099] The designed device overcomes this limitation by using a partial glove (60) that covers part of the thumb, metacarpals, and hand cover, and is sealed to the cover by suitable seats, with specific protrusions (61, 62) on the glove introduced into these seats. Figure 15 Specifically, the glove seal is ensured by the compression of these protrusions within the cover seat, achieved by making the diameter of these protrusions slightly smaller than that of the seat on the cover and the thickness slightly greater than that of the seat on the cover.

Claims

1. Anthropomorphic robot hand, including: -Frame (00); - Metacarpal (10), fixed to the frame (00) so that it can rotate and translate along the rotation axis (180) of the cylindrical joint; - Thumb (11), fixed to the metacarpal (10) so that it can rotate along the axis (140) of the rotational joint; -Actuation device for the thumb (11) and the metacarpal (10); - At least two fingers fixed to the frame and corresponding actuation devices for driving the fingers, the fingers being able to be positioned opposite the thumb; Its features The actuating devices for the thumb and the metacarpals include: - A first submechanism actuated by a first motor (M2) integrated with the thumb (11) and configured to move a gear ring (T2) via a worm gear (R2), the gear ring being fixed to engage with corresponding teeth provided on the metacarpal (10) such that rotation of the proximal phalanx relative to the metacarpal corresponds to rotation of the gear ring (T2). - A second submechanism actuated by a second motor (M3) integrated with the frame (00) and configured to move a ring (T3) via a worm gear (R3), the ring being configured to rotate the metacarpal (10) relative to the axis of rotation (180) of the cylindrical joint via a clutch (C1).

2. The anthropomorphic robot hand according to claim 1, characterized in that, The ring (T3) has a plurality of teeth on its side surface that mesh with corresponding teeth on the side surface of the clutch (C1), which rotates freely on the same axis of rotation (180) of the cylindrical joint.

3. The anthropomorphic robot hand according to claim 2, characterized in that, The actuation device further includes a Bavarian washer (S1) configured to be compressed under external stress, thereby allowing the toothed ring (T2) to translate along the axis (140) of the rotary joint and temporarily disengage from the corresponding tooth provided on the metacarpal (10).

4. The anthropomorphic robot hand according to claim 3, characterized in that, The rigidity of the spring (S1) and the profile of the teeth on the toothed ring (T2) and the metacarpal bone are clearly fixed such that the torque required to achieve this disengagement is higher than the torque applied by the motor (M2) to rotate the thumb (11).

5. The anthropomorphic robot hand according to claim 2, 3, or 4, characterized in that, The clutch (C1) is provided with a plurality of holes, the axes of which are parallel to the rotation axis of the clutch itself. The holes are configured to receive a pin (P1) integral with the metacarpal (10), so that the two elements are integral during rotation along the rotation axis (180) of the cylindrical joint. The holes are also configured to release the pin (P1) when the metacarpal translates along the rotation axis (180) of the cylindrical joint, so that the metacarpal can rotate freely relative to the frame (00). The actuation device further includes a spring (110) located between the metacarpal (10) and the frame (00), the spring (110) being configured to push the metacarpal (10) toward the clutch (C1) along the rotation axis of the cylindrical joint.

6. The anthropomorphic robot hand according to claim 5, characterized in that, The hole provided on the clutch (C1) has a flared opening in the portion facing the metacarpal bone, the flared opening being configured to facilitate the introduction of the pin (P1).

7. The anthropomorphic robot hand according to any one of the preceding claims, characterized in that, The second submechanism can be manually actuated by translating the metacarpal bone, causing the pin (P1) to disengage from the hole provided on the clutch.

8. The anthropomorphic robot hand according to any one of the preceding claims further includes a Bavarian washer (S2) located between the clutch (C1) and the frame (00), the Bavarian washer between the clutch and the frame being configured to be compressed under high rotational stress of the thumb, thereby allowing the clutch (C1) to translate upward along the axis of rotation (180) of the cylindrical joint, thereby disengaging the clutch from the ring (T3).

9. The anthropomorphic robot hand according to claim 8, characterized in that, The rigidity of the Bausch washer (S2) between the clutch and the frame makes the torque required to achieve this disengagement higher than the torque applied by the motor (M3) to rotate the metacarpal (10).

10. The anthropomorphic robot hand according to any one of the preceding claims, characterized in that, The metacarpal (10) is fixed by two cylindrical joints to an axis integral with the frame at the axis of rotation (180) of the cylindrical joints. Between the axis and the metacarpal, at these two hinges, elastic cylinders (1111 and 1122) are inserted, which allow small-angle rotation.

11. The anthropomorphic robot hand according to any one of the preceding claims, characterized in that, A second Bavarian washer (S3) is provided between the metacarpal and the frame. The function of the second Bavarian washer is to absorb impacts that tend to push the metacarpal (10) downward.

12. The anthropomorphic robot hand according to any one of the preceding claims further includes a control electronic board, the control electronic board being configured to receive input control signals from a user and control the motors (M2, M3) according to the control signals.

13. The humanoid robot hand according to any one of the preceding claims further includes a pressure sensor disposed at the tip of the thumb; and the control electronics are further configured to receive an input signal from the pressure sensor and, if the pressure sensor detects a decrease in applied pressure when the user does not extend the hand, increase the torque applied by the first motor (M2).

14. The anthropomorphic robot hand according to any one of the preceding claims, characterized in that, The axis of rotation (180) of the cylindrical joint is inclined relative to the axis of the forearm, and the inclination is achieved by rotating the two connecting flanges (08 and 09) that connect the frame (00) to the metacarpal (10).

15. The anthropomorphic robot hand according to any one of the preceding claims, characterized in that, The thumb is configured to take a position relative to the frame: - Lateral position (c), wherein the thumb is substantially coplanar with the palm (00); - Three-finger position (a), wherein the thumb forms an angle of approximately 90° with the palm (00); - Neutral position (b), between the first two positions.

16. The anthropomorphic robot hand according to any one of the preceding claims further includes a thumb position sensor configured to detect the angle formed by the thumb relative to the frame, and an inertial unit configured to detect the angle formed by the anthropomorphic robot hand in space.

17. The anthropomorphic robot hand according to claim 16, characterized in that, The thumb position sensor includes: a Hall effect sensor (001) integrated with the frame (00) and two magnets (1001, 1002) integrated with the metacarpal bone (10).

18. The anthropomorphic robot hand according to claim 16 or 17, characterized in that, The anthropomorphic robot hand is configured to change the type of grip to be performed based on signals detected by the electromyography sensor, the thumb position sensor, and the inertial unit.

19. The anthropomorphic robot hand according to any one of the preceding claims, characterized in that, The frame is covered by a cover (01) configured to protect the actuator and the internal control electronics board, and the anthropomorphic robot hand also includes a partial glove (60) configured to cover the thumb and the metacarpal bones and seal the cover.

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