Multi-degree-of-freedom dexterous hand thumb structure and control method thereof

Abstract

The application relates to a multi-degree-of-freedom dexterous hand thumb structure and a control method thereof, and relates to the field of robot dexterous hands. According to the scheme, dexterous hand electric cylinders are inversely integrated in two knuckles, adjacent knuckles are directly driven to rotate by motor shafts, the transmission chain is short, and response is fast. Meanwhile, side swing electric cylinders are arranged above driven gear plates, a base support is fixed to a rotating base, three levels of movements of bending, side swing and overall rotation are decoupled in structure, four degrees of freedom do not interfere with each other, the overall rotation degree of freedom makes the thumb more easily form a finger posture with the remaining four fingers, and complex operations such as screwing and multi-angle pinching are adapted. The gear meshing mode is adopted for rotary drive, the electric cylinder is arranged on the side of the main body of the dexterous hand, and the constraint of the rotary torque output and the knuckle radial size is considered. A touch sensor is integrated at a finger tip, real-time feedback input is provided for a grasping torque closed loop, and a controller can dynamically adjust a knuckle output torque according to a contact state.

Description

Technical Field

[0001] This invention relates to the field of robotic dexterity hand technology, and in particular to a multi-degree-of-freedom dexterity hand thumb structure and its control method. Background Technology

[0002] As the core end effector for achieving fine manipulation and human-machine interaction, the dexterous hand of a humanoid robot directly determines the overall hand's operational capabilities through the configuration of its thumb's degrees of freedom and the degree of drive integration. Currently, thumb structures with combined flexion and lateral swing functions have become the mainstream technology in the industry, widely used in service robots, industrial assembly, and rehabilitation assistive devices. In conventional designs, the thumb typically adopts a multi-joint serial configuration. The drive sources for each degree of freedom are usually arranged at the end of the palm or forearm in the form of micro-motors with reducers, chord drives, or linkage mechanisms. Power is transmitted to the finger joints through a flexible transmission medium to achieve the thumb's flexion, extension, and lateral swinging movements.

[0003] However, the aforementioned existing technologies still have some shortcomings in practical applications: On the one hand, the layout of external drive plus remote transmission results in excessively long transmission links, and the tendon ropes or connecting rods have complex wiring in a narrow space, which not only increases friction loss and transmission clearance, but also makes it difficult to further reduce the structural volume of the thumb base, limiting the compact design of the overall size of the dexterous hand; on the other hand, the existing thumb structure generally lacks the overall rotational freedom around its own longitudinal axis, and the two degrees of freedom of bending and lateral swing are insufficient to cover the entire movement space of the human thumb, resulting in limited posture adaptability when facing complex operation tasks such as twisting and multi-angle pinching; in addition, most solutions do not integrate tactile sensing units at the fingertips, lacking real-time force feedback during the grasping process, and the controller can only rely on preset parameters to output open-loop torque, making it difficult to adaptively adjust the clamping force according to the actual contact state of the object, which can easily cause damage to fragile items or unstable gripping of rigid objects. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-degree-of-freedom dexterous hand thumb structure and its control method to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a multi-degree-of-freedom dexterous hand thumb structure, comprising: The first knuckle assembly includes a first knuckle of the thumb and a first knuckle dexterous cylinder. The first knuckle dexterous cylinder is built into the first knuckle of the thumb. The motor shaft of the first knuckle dexterous cylinder is connected to the second knuckle of the thumb. The motor shaft of the first knuckle dexterous cylinder forms a first knuckle rotation axis A to drive the first knuckle of the thumb to rotate relative to the second knuckle of the thumb around the first knuckle rotation axis A. The second knuckle assembly includes the second knuckle of the thumb and a second knuckle dexterous cylinder. The second knuckle dexterous cylinder is built into the second knuckle of the thumb. The motor shaft of the second knuckle dexterous cylinder is connected to the first base bracket and the second base bracket on both sides respectively. The motor shaft of the second knuckle dexterous cylinder forms the second knuckle rotation axis B to drive the second knuckle of the thumb to rotate around the second knuckle rotation axis B relative to the first base bracket and the second base bracket. A side-swing drive assembly includes a side-swing dexterous electric cylinder, a first rotating base, and a second rotating base. The motor shaft of the side-swing dexterous electric cylinder is connected to the first rotating base and the second rotating base on both sides, respectively. The motor shaft of the side-swing dexterous electric cylinder forms a side-swing shaft C to drive the first phalanx and the second phalanx of the thumb to rotate as a whole around the side-swing shaft C relative to the first rotating base and the second rotating base. A rotary drive assembly includes a rotary smart electric cylinder, a main drive gear, and a driven gear disk. The main drive gear is mounted on the motor shaft of the rotary smart electric cylinder. The main drive gear meshes with a gear on the driven gear disk. The rotary smart electric cylinder drives the driven gear disk to rotate through the main drive gear, thereby causing the first phalanx of the thumb, the second phalanx of the thumb, and the lateral swing drive assembly to rotate as a whole. The side-swinging dexterous electric cylinder is mounted on the driven gear disk, the first base bracket and the second base bracket are respectively fixed on the first rotating base and the second rotating base, and the rotating dexterous electric cylinder is mounted on the dexterous hand body.

[0006] In some embodiments, the first knuckle dexterous flashlight cylinder is inverted and built into the first knuckle of the thumb; The second knuckle dexterous flashlight cylinder is installed in the second knuckle of the thumb in an inverted manner.

[0007] In some embodiments, a tactile sensor is integrated at the tip of the first phalanx of the thumb.

[0008] In some embodiments, the motor shaft of the second knuckle-operated dexterous electric cylinder is connected to the first base bracket and the second base bracket respectively by screws on both sides; The motor shaft of the side-swinging dexterous electric cylinder is connected to the first rotating base and the second rotating base on both sides by screws.

[0009] In some embodiments, the main drive gear is fixed to the motor shaft of the rotary dexterous cylinder by screws.

[0010] In some embodiments, the side-swinging dexterous electric cylinder is fixed above the driven gear disk, and a bearing is interference-fitted onto a cylinder below the driven gear disk. The driven gear disk is rotatably connected to a bearing hole on the dexterous hand body through the bearing, which serves as a rotation center and provides support.

[0011] Secondly, the present invention provides a control method for a multi-degree-of-freedom dexterous hand thumb structure, applied to the multi-degree-of-freedom dexterous hand thumb structure as described above, comprising: The first knuckle is controlled to operate the dexterous electric cylinder, which drives the first knuckle of the thumb to rotate relative to the second knuckle of the thumb around the first knuckle rotation axis A through its motor shaft, thereby realizing the bending movement of the first knuckle; The second knuckle dexterous electric cylinder is controlled to work, and its motor shaft drives the second knuckle of the thumb to rotate around the second knuckle rotation axis B relative to the first base bracket and the second base bracket, thereby realizing the bending movement of the second knuckle. The side-swinging dexterous electric cylinder is controlled to work, and its motor shaft drives the first and second phalanges of the thumb to rotate as a whole around the side-swinging axis C relative to the first and second rotating bases, thereby realizing the side-swinging movement of the thumb; The rotating dexterous electric cylinder is controlled to operate, and its motor shaft drives the main drive gear to rotate, which in turn drives the driven gear disk to rotate, thereby realizing the overall rotational movement of the thumb.

[0012] In some embodiments, the method further includes: Acquire tactile signals collected by the tactile sensor; Based on the tactile signal, adjust the output torque of the first knuckle dexterous hand cylinder and / or the second knuckle dexterous hand cylinder.

[0013] In some embodiments, the first knuckle flexion movement, the second knuckle flexion movement, the thumb lateral swing movement, and the thumb overall rotation movement are independently driven and controlled by the first knuckle dexterous electric cylinder, the second knuckle dexterous electric cylinder, the lateral swing dexterous electric cylinder, and the rotation dexterous electric cylinder, respectively.

[0014] In some embodiments, the method further includes: Based on the target grasping posture, determine the target rotation angle of each of the first knuckle dexterous electric cylinder, the second knuckle dexterous electric cylinder, the side-swing dexterous electric cylinder, and the rotary dexterous electric cylinder; The motor shafts of the first knuckle dexterous hand cylinder, the second knuckle dexterous hand cylinder, the side-swing dexterous hand cylinder, and the rotary dexterous hand cylinder are respectively controlled to rotate to their respective target rotation angles.

[0015] The beneficial effects of the technical solution provided by this invention include at least the following: This technical solution integrates inverted electric cylinders within two finger joints, with the motor shaft directly driving the rotation of adjacent finger joints. This eliminates intermediate transmission links such as tendons and connecting rods, thus eliminating transmission backlash and return error. The control accuracy of each joint position directly depends on the resolution of the electric cylinder encoder, resulting in a short transmission chain and fast response. Simultaneously, by placing the lateral swing electric cylinder above the driven gear disk and fixing the base bracket to the rotating base, the three levels of motion—bending, lateral swing, and overall rotation—are structurally decoupled. The four degrees of freedom do not interfere with each other and can be controlled independently. The thumb's working space is significantly expanded compared to conventional solutions with only bending and lateral swing degrees of freedom. The overall rotational degree of freedom makes it easier for the thumb to form an opposing finger posture with the other four fingers, adapting to complex operations such as twisting and multi-angle pinching. The rotational drive uses a gear meshing method to place the electric cylinder on the side of the dexterous hand body, avoiding the need to add a drive source within the already compact finger joints, thus balancing the constraints of rotational torque output and finger joint radial dimensions. The fingertip-integrated tactile sensor provides real-time feedback input for the gripping torque closed loop, enabling the controller to dynamically adjust the output torque of the knuckles based on the contact state, reducing the risk of damage to fragile objects and slippage of rigid objects. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0017] Figure 1 A cross-sectional view of a multi-degree-of-freedom dexterous hand thumb structure provided by an exemplary embodiment of the present invention is shown.

[0018] Figure 2 A top view of a multi-degree-of-freedom dexterous hand thumb structure provided by an exemplary embodiment of the present invention is shown.

[0019] Figure 3 A schematic diagram of a rotary dexterous electric cylinder, a main drive gear, and a driven gear disk of a multi-degree-of-freedom dexterous hand thumb structure provided in an exemplary embodiment of the present invention is shown.

[0020] Figure 4 A flowchart illustrating a control method for a multi-degree-of-freedom dexterous hand thumb structure provided by an exemplary embodiment of the present invention is shown.

[0021] In the diagram: 1. First knuckle of the thumb; 2. Tactile sensor; 3. First knuckle dexterous cylinder; 4. Second knuckle of the thumb; 5. Second knuckle dexterous cylinder; 6. First base bracket; 7. Second base bracket; 8. First rotating base; 9. Second rotating base; 10. Side-swinging dexterous cylinder; 11. Driven gear plate; 12. Rotating dexterous cylinder; 13. Main drive gear; 14. Bearing. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] In this specification, identical components are represented by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "upper," and "lower" used in the following description refer to directions in the accompanying drawings, while the terms "bottom surface," "top surface," "inner," and "outer" refer to directions towards or away from a specific component. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this specification, "multiple" means two or more.

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] Example 1 like Figures 1 to 3 As shown, this embodiment provides a multi-degree-of-freedom dexterity hand thumb structure, including four functional modules: a first phalanx assembly, a second phalanx assembly, a lateral swing drive assembly, and a rotation drive assembly. The four functional modules are arranged in series from the fingertip side to the palm side, enabling the thumb to have four active degrees of freedom of movement: first phalanx bending, second phalanx bending, lateral swing, and overall rotation. This allows for multi-directional and multi-posture movement capabilities close to those of a human thumb within a limited structural space, meeting the needs of dexterity hands for enveloping and precisely grasping objects of various shapes and sizes.

[0026] The first joint assembly includes the first joint of the thumb 1 and a first joint dexterity cylinder 3. The first joint dexterity cylinder 3 is built into the first joint of the thumb 1, and its motor shaft is connected to the second joint of the thumb 4. The motor shaft of the first joint dexterity cylinder 3 forms the first joint rotation axis A. When the first joint dexterity cylinder 3 is energized, its motor shaft generates a rotational torque relative to the second joint of the thumb 4, driving the first joint of the thumb 1 to rotate around the first joint rotation axis A relative to the second joint of the thumb 4, thus achieving the bending and extension movements of the first joint. By embedding the drive cylinder inside the joint housing and connecting the motor shaft to the adjacent joint, the drive source and the motion joint are integrated into the same motion chain, avoiding the problems of exposed transmission links and cables caused by external drives. This effectively reduces the overall radial dimension of the thumb, improving the structural compactness and human-like appearance of the dexterity hand.

[0027] The second knuckle assembly includes the second knuckle of the thumb 4 and the second knuckle dexterous cylinder 5. The second knuckle dexterous cylinder 5 is built into the second knuckle of the thumb 4. The motor shaft of the second knuckle dexterous cylinder 5 is connected to the first base bracket 6 and the second base bracket 7 on both sides, forming the second knuckle rotation axis B. When the second knuckle dexterous cylinder 5 is energized, its motor shaft generates a rotational torque relative to the first base bracket 6 and the second base bracket 7, driving the second knuckle of the thumb 4 to rotate around the second knuckle rotation axis B relative to the first base bracket 6 and the second base bracket 7, thus achieving the bending and extending movements of the second knuckle. The first base bracket 6 and the second base bracket 7 are fixed to the first rotating base 8 and the second rotating base 9, respectively. The rotational motion of the second knuckle assembly is transmitted to the upper lateral swing drive assembly through the base brackets, forming a stable motion transmission link to ensure that the bending motion of the second knuckle is not interfered with by the lateral swing motion and the overall rotational motion.

[0028] The lateral swing drive assembly includes a lateral swing dexterous hand cylinder 10, a first rotating base 8, and a second rotating base 9. The motor shaft of the lateral swing dexterous hand cylinder 10 is connected to both sides of the first rotating base 8 and the second rotating base 9, respectively, forming a lateral swing axis C. When the lateral swing dexterous hand cylinder 10 is energized, its motor shaft generates a rotational torque relative to the first rotating base 8 and the second rotating base 9, driving the first phalanx 1 and the second phalanx 4 of the thumb to rotate as a whole around the lateral swing axis C relative to the first rotating base 8 and the second rotating base 9, thus realizing the lateral swinging motion of the thumb. This lateral swinging motion allows the thumb to deflect laterally within the palm plane, coordinating with the other four fingers to complete various grasping configurations such as interlocking and side pinching, significantly expanding the grasping posture space of the dexterous hand.

[0029] The rotary drive assembly includes a rotary dexterous hand cylinder 12, a main drive gear 13, and a driven gear disk 11. The main drive gear 13 is mounted on the motor shaft of the rotary dexterous hand cylinder 12, and meshes with the gears on the driven gear disk 11. The rotary dexterous hand cylinder 12 is mounted on the dexterous hand body. When the rotary dexterous hand cylinder 12 is powered on, its motor shaft drives the main drive gear 13 to rotate. The main drive gear 13 transmits the rotational motion to the driven gear disk 11 through meshing with the gears on the driven gear disk 11, driving the driven gear disk 11 to rotate around its own axis. This, in turn, drives the side-swinging dexterous hand cylinder 10, the first phalanx 1 of the thumb, and the second phalanx 4 of the thumb, which are mounted above the driven gear disk 11, to rotate as a whole, thus realizing the axial rotational movement of the thumb. By using gear transmission to place the rotary drive source on the main body of the dexterous hand, rather than integrating it inside the thumb knuckle, it avoids adding another set of drive cylinders in the already highly compact knuckle space. On the other hand, the gear meshing achieves speed reduction and torque increase, improving the output torque and positioning accuracy of the overall rotary motion.

[0030] The side-swinging dexterous electric cylinder 10 is mounted on the driven gear disk 11, so that the side-swinging drive assembly rotates synchronously with the driven gear disk 11, ensuring the correct kinematic coupling between the side-swinging motion and the overall rotational motion. The first base bracket 6 and the second base bracket 7 are respectively fixed on the first rotating base 8 and the second rotating base 9, so that the bending motion of the second knuckle assembly can be correctly transmitted to the side-swinging drive assembly.

[0031] In this embodiment, four dexterous electric cylinders independently drive four degrees of freedom of motion. There is no mechanical coupling or motion interference between the degrees of freedom. The control system can independently adjust the rotation angle and output torque of each degree of freedom, so that the thumb can reach any target posture in the workspace and meet the operation requirements of multi-task grasping.

[0032] Example 2 like Figures 1 to 3 As shown, this embodiment, based on embodiment one, further defines the installation method, connection method, and auxiliary structure of each dexterous electric cylinder: The first-joint dexterous electric cylinder 3 is inverted and built into the first joint 1 of the thumb, while the second-joint dexterous electric cylinder 5 is inverted and built into the second joint 4 of the thumb. The inverted design means that the output end of the electric cylinder, i.e., the motor shaft, faces the adjacent joint, while the fixed end of the cylinder body faces the fingertip of the same joint. With this inverted design, the motor shaft extends towards the joint's rotation center, allowing the rotational torque to act directly on the adjacent joint. This minimizes the transmission path, maximizes transmission efficiency, and reduces gaps and wear caused by intermediate transmission links. The cylinder body occupies space within the joint near the fingertip, while the space near the palm is used for wiring and connecting structures, maximizing the utilization of the joint's internal space. The inverted design also brings the cylinder's center of gravity closer to the joint root, reducing the rotational inertia of the moving parts and improving the response speed and dynamic performance of the joint's bending motion.

[0033] A tactile sensor 2 is integrated at the tip of the first joint 1 of the thumb. The tactile sensor 2 can sense the contact force, contact area, and contact position between the thumb tip and the object being grasped in real time. By placing the tactile sensor 2 at the fingertip, the thumb can obtain tactile feedback the moment it contacts the object. This provides the hardware basis for adjusting the output torque based on the tactile signal in subsequent control methods. This allows the dexterous hand to adaptively adjust the grasping force when grasping fragile, flexible, or objects of unknown shape, avoiding damage to the object due to excessive gripping force or slippage due to insufficient gripping force.

[0034] The motor shaft of the second-joint dexterous electric cylinder 5 is connected to the first base bracket 6 and the second base bracket 7 on both sides by screws. The motor shaft of the side-swinging dexterous electric cylinder 10 is connected to the first rotating base 8 and the second rotating base 9 on both sides by screws. The screw connection is a detachable connection, which can be quickly disassembled and assembled during the maintenance, replacement or debugging of the electric cylinder, reducing the difficulty of assembly and maintenance; the screw connection can provide sufficient connection rigidity and torsional resistance to ensure that the rotational torque output by the motor shaft is reliably transmitted to the base bracket and the rotating base, avoiding loosening or slippage during operation; the symmetrical arrangement of screws on both sides makes the force on the motor shaft symmetrical and balanced, eliminating the off-center load torque caused by unilateral connection, and extending the service life of the electric cylinder bearings and brackets.

[0035] The main drive gear 13 is fixed to the motor shaft of the rotary smart hand cylinder 12 by screws. By fixing the main drive gear 13 with screws, a rigid connection is formed between the main drive gear 13 and the motor shaft, ensuring that the torque output by the rotary smart hand cylinder 12 is transmitted to the main drive gear 13 without loss. At the same time, the screw fixing method facilitates the disassembly and replacement of the main drive gear 13, and can be carried out quickly when the gear wears or when it is necessary to replace the gear with a gear of different gear ratio.

[0036] A side-swinging dexterous electric cylinder 10 is fixed above the driven gear disk 11, and a bearing 14 is interference-fitted onto the cylinder below the driven gear disk 11. The driven gear disk 11 is rotatably connected to the bearing hole on the dexterous hand body through the bearing 14, which serves as the rotation center and provides support. The interference fit of the bearing 14 on the cylinder below the driven gear disk 11 ensures no relative rotation between the bearing 14 and the driven gear disk 11, guaranteeing coaxiality and transmission accuracy of the rotational motion. The bearing 14, embedded in the bearing hole on the dexterous hand body, provides radial support and axial positioning for the driven gear disk 11 and all moving components above it, bearing the radial and axial loads generated during thumb movement. It also provides a low-friction rotating pair for the rotation of the driven gear disk 11, allowing the rotating dexterous electric cylinder 12 to drive the driven gear disk 11 to rotate only by overcoming gear meshing friction and load torque, thus reducing the power consumption of the rotational drive components. The bearing 14 also serves as the rotation center, ensuring that the rotation axis of the driven gear disk 11 coincides with the geometric axis of the bearing hole on the dexterous hand body, thus avoiding eccentric oscillation during rotation and ensuring the kinematic accuracy of the overall rotation of the thumb.

[0037] Example 3 Combination Figures 1 to 4 This embodiment provides a control method for the thumb structure of a multi-degree-of-freedom dexterous hand, applied to the thumb structure of the multi-degree-of-freedom dexterous hand in Embodiment 1 or Embodiment 2. The method includes the following steps: Step S1: Control the first knuckle dexterous electric cylinder 3 to work, drive the first knuckle 1 of the thumb to rotate around the first knuckle rotation axis A relative to the second knuckle 4 of the thumb through its motor shaft, so as to realize the bending movement of the first knuckle.

[0038] Specifically, the controller sends a drive command to the first joint dexterous hand cylinder 3. Upon receiving the command, the motor inside the first joint dexterous hand cylinder 3 generates a rotational torque. This torque is transmitted through the motor shaft, i.e., the first joint rotation axis A, to the first joint 1 of the thumb, causing the first joint 1 of the thumb to rotate relative to the second joint 4 of the thumb around the first joint rotation axis A. The bending motion of the first joint allows the thumb tip to retract towards the palm, completing the pinching and locking action of the object.

[0039] Step S2: Control the second knuckle dexterous electric cylinder 5 to work, drive the second knuckle 4 of the thumb to rotate around the second knuckle rotation axis B relative to the first base bracket 6 and the second base bracket 7 through its motor shaft, so as to realize the bending movement of the second knuckle.

[0040] Specifically, the controller sends a drive command to the second knuckle dexterous cylinder 5. Upon receiving the command, the motor inside the second knuckle dexterous cylinder 5 generates a rotational torque. This torque is transmitted to the second knuckle 4 of the thumb via the motor shaft, i.e., the second knuckle rotation axis B, causing the second knuckle 4 of the thumb to rotate relative to the first base support 6 and the second base support 7 around the second knuckle rotation axis B. The bending motion of the second knuckle coordinates with the bending motion of the first knuckle, allowing the thumb to form bending shapes with different curvatures to adapt to the enveloping needs of objects of different sizes and shapes.

[0041] Step S3: Control the operation of the side-swinging dexterous electric cylinder 10, which drives the first phalanx 1 and the second phalanx 4 of the thumb to rotate around the side-swinging axis C relative to the first rotating base 8 and the second rotating base 9 through its motor shaft, thereby realizing the side-swinging movement of the thumb.

[0042] Specifically, the controller sends a drive command to the lateral swing dexterous hand cylinder 10. Upon receiving the command, the motor inside the lateral swing dexterous hand cylinder 10 generates a rotational torque. This torque acts on the first phalanx 1 and the second phalanx 4 of the thumb via the motor shaft, i.e., the lateral swing shaft C, causing the first phalanx 1 and the second phalanx 4 of the thumb to rotate as a whole around the lateral swing shaft C. This lateral swing motion causes the thumb to deflect laterally within the palmar plane, enabling thumb-palm and lateral gripping actions, thus expanding the types of grasping configurations available for dexterous hands.

[0043] Step S4: Control the operation of the rotary dexterous electric cylinder 12, which drives the main drive gear 13 to rotate through its motor shaft and drives the driven gear disk 11 to rotate, thereby realizing the overall rotational movement of the thumb.

[0044] Specifically, the controller sends a drive command to the rotary dexterous cylinder 12. Upon receiving the command, the motor inside the rotary dexterous cylinder 12 generates a rotational torque. This torque is transmitted through the motor shaft to the main drive gear 13. The main drive gear 13 meshes with the gear on the driven gear disk 11, transmitting the rotational motion to the driven gear disk 11. The driven gear disk 11 then drives the side-swinging dexterous cylinder 10, the first phalanx 1 of the thumb, and the second phalanx 4 of the thumb to rotate as a whole around the axis of the driven gear disk 11. This overall rotational motion of the thumb allows it to perform internal and external rotational movements around its own longitudinal axis, simulating the pronation and supination movements of the human thumb. This enables the dexterous hand to possess the necessary motor abilities to perform tasks such as twisting and screwing.

[0045] The execution order of steps S1 to S4 can be arbitrarily arranged and combined according to the actual needs of the crawling task, and can also be executed simultaneously. There is no necessary sequential dependency between the steps.

[0046] Example 4 Combination Figures 1 to 4Based on Embodiment 3, this embodiment further defines a torque adjustment control method based on tactile feedback. In addition to steps S1 to S4 of Embodiment 3, this method also includes the following steps: Step S5: Acquire the tactile signal collected by tactile sensor 2.

[0047] Specifically, after the tip of the first phalanx 1 of the thumb makes contact with an object, the tactile sensor 2 integrated at the tip of the first phalanx 1 of the thumb detects the contact force signal in real time and transmits the tactile signal to the controller. The tactile signal includes, but is not limited to, normal contact force, tangential friction force, and contact area distribution information. Real-time acquisition of the tactile signal enables the controller to grasp the actual contact state between the tip of the thumb and the object, providing feedback input for subsequent torque closed-loop control and avoiding problems caused by the controller performing open-loop control based solely on preset parameters, resulting in excessive or insufficient gripping force.

[0048] Step S6: Adjust the output torque of the first knuckle dexterous cylinder 3 and / or the second knuckle dexterous cylinder 5 according to the tactile signal.

[0049] Specifically, the controller compares the received tactile signal with a preset target contact force: when the tactile signal indicates that the actual contact force is less than the target contact force, the controller increases the output torque of the first knuckle dexterous hand cylinder 3 and / or the second knuckle dexterous hand cylinder 5, causing the first knuckle 1 and / or the second knuckle 4 of the thumb to further bend and retract, increasing the gripping force on the object; when the tactile signal indicates that the actual contact force reaches or exceeds the target contact force, the controller maintains or decreases the output torque to prevent the gripping force from continuing to increase. Through tactile feedback, a closed-loop torque control is formed, enabling the dexterous hand to adaptively adjust the gripping force according to the actual stiffness, shape, and surface characteristics of the object being grasped, effectively protecting fragile and flexible objects from damage while ensuring reliable gripping of rigid objects.

[0050] In this embodiment, the feedback signal from the tactile sensor 2 acts simultaneously on the first knuckle dexterous cylinder 3 and the second knuckle dexterous cylinder 5. The controller can adjust the output torque distribution ratio of the two cylinders according to the different contact positions in the tactile signal. When the tactile signal indicates that the contact point is close to the fingertip, the output torque of the first knuckle dexterous cylinder 3 is adjusted primarily; when the tactile signal indicates that the contact point is close to the joint between the first and second knuckles, the output torque of the second knuckle dexterous cylinder 5 is adjusted primarily. This torque distribution strategy matches the application position of the grasping force with the actual contact position, improving the stability of the grasp and the energy utilization efficiency.

[0051] Example 5 Combination Figures 1 to 4Based on Embodiment 3, this embodiment further defines an independent drive control method and an angle control method based on the target grasping posture. In this method: The bending motion of the first and second knuckles, the lateral swing motion of the thumb, and the overall rotational motion of the thumb are independently driven and controlled by the first knuckle dexterous cylinder 3, the second knuckle dexterous cylinder 5, the lateral swing dexterous cylinder 10, and the rotational dexterous cylinder 12, respectively. Independent drive control means that each of the four dexterous cylinders receives independent control commands and operates according to the required angle, speed, and torque. Changes in the motion state of one dexterous cylinder do not affect the motion states of the other three. With independent drive control, the motion control of each degree of freedom is decoupled, and the controller does not need to handle the kinematic coupling relationships between multiple degrees of freedom, reducing the complexity of the control algorithm. Each degree of freedom can be independently controlled for position, speed, or torque, meeting the differentiated requirements of motion accuracy and output torque for different grasping tasks. When a degree of freedom reaches the target position, the dexterous cylinder can enter a holding mode or a zero-torque mode to reduce power consumption without affecting the continued movement of the other degrees of freedom.

[0052] Furthermore, the method also includes the following steps: Step S7: Based on the target grasping posture, determine the target rotation angle of each of the first knuckle dexterous hand cylinder 3, the second knuckle dexterous hand cylinder 5, the side-swing dexterous hand cylinder 10, and the rotational dexterous hand cylinder 12.

[0053] Specifically, the controller receives target grasping posture commands input by the host system or operator. These target grasping postures include the target bending angle of the first phalanx 1 of the thumb, the target bending angle of the second phalanx 4 of the thumb, the target lateral tilt angle of the thumb relative to the palm, and the target rotation angle of the thumb around its longitudinal axis. Based on these target posture parameters, the controller uses inverse kinematics calculations to determine the first target angle required for the motor shaft of the first phalanx dexterous cylinder 3 to rotate, the second target angle required for the motor shaft of the second phalanx dexterous cylinder 5 to rotate, the third target angle required for the motor shaft of the lateral tilt dexterous cylinder 10 to rotate, and the fourth target angle required for the motor shaft of the rotation dexterous cylinder 12 to rotate. Through inverse kinematics calculations from the target posture to the target angles of each cylinder, the grasping requirements in the task space are mapped to drive commands in the joint space. This allows the operator or host system to describe only the desired thumb posture without calculating the rotation of each cylinder individually, simplifying the operation interface and reducing programming complexity.

[0054] Step S8: Control the motor shafts of the first knuckle dexterous hand cylinder 3, the second knuckle dexterous hand cylinder 5, the side-swing dexterous hand cylinder 10 and the rotary dexterous hand cylinder 12 to rotate to their respective target rotation angles.

[0055] Specifically, the controller simultaneously sends position control commands to four dexterous hand cylinders. The encoder inside each cylinder detects the actual rotation angle of the motor shaft in real time and feeds it back to the controller. The controller compares the actual rotation angle with the target rotation angle and drives the motor shaft to rotate to the target angle using a closed-loop control algorithm. When all four motor shafts of the dexterous hand cylinders reach their respective target rotation angles, the thumb reaches the target grasping posture. The simultaneous rotation of the four cylinders shortens the movement time from the initial posture to the target posture, improving the grasping response speed of the dexterous hand. Closed-loop position control ensures the positioning accuracy of each degree of freedom, enabling the thumb to accurately reach the target posture, meeting the requirements of applications with high positional accuracy, such as precision assembly and delicate operations.

[0056] It should be noted that the above embodiments one to five are not independent solutions. Those skilled in the art can combine the structural details in embodiment two with the method steps in embodiments three to five according to actual needs.

[0057] For example, in the angle control method based on target grasping posture in Embodiment 5, if a tactile sensor 2 is integrated at the tip of the first phalanx 1 of the thumb, then during the rotation of each dexterous electric cylinder to the target rotation angle in step S8, the controller can simultaneously execute the tactile feedback torque adjustment in steps S5 and S6 of Embodiment 4. That is, torque closed-loop control is superimposed on position closed-loop control to achieve position-torque hybrid control. This hybrid control method allows the thumb to correct the output torque in real time based on contact force feedback as it approaches the target posture, avoiding rigid collision of the thumb with the object surface at a preset speed, thus achieving compliant contact and adaptive grasping.

[0058] For example, in the structure of Embodiment 1, both the first knuckle-mounted dexterous electric cylinder 3 and the second knuckle-mounted dexterous electric cylinder 5 are inverted and built into the corresponding knuckles. In the control method of Embodiment 3, the correspondence between the rotation direction of the motor shaft of the first knuckle-mounted dexterous electric cylinder 3 and the bending direction of the knuckle is determined by the inverted mounting method. When generating drive commands, the controller maps the rotation direction of the motor shaft according to the inverted mounting direction of the cylinders to ensure that the control commands are consistent with the actual bending direction of the knuckles.

[0059] In the embodiments disclosed in this invention, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "linking" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments disclosed in this invention according to the specific circumstances.

[0060] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A multi-degree-of-freedom dexterous hand thumb structure, characterized in that, include: The first knuckle assembly includes a first knuckle of the thumb (1) and a first knuckle dexterous cylinder (3), the first knuckle dexterous cylinder (3) being built into the first knuckle of the thumb (1), the motor shaft of the first knuckle dexterous cylinder (3) being connected to the second knuckle of the thumb (4), the motor shaft of the first knuckle dexterous cylinder (3) forming a first knuckle rotation axis A to drive the first knuckle of the thumb (1) to rotate relative to the second knuckle of the thumb (4) around the first knuckle rotation axis A; The second knuckle assembly includes the second knuckle of the thumb (4) and the second knuckle dexterous cylinder (5). The second knuckle dexterous cylinder (5) is built into the second knuckle of the thumb (4). The motor shaft of the second knuckle dexterous cylinder (5) is connected to the first base bracket (6) and the second base bracket (7) on both sides respectively. The motor shaft of the second knuckle dexterous cylinder (5) constitutes the second knuckle rotation axis B to drive the second knuckle of the thumb (4) to rotate around the second knuckle rotation axis B relative to the first base bracket (6) and the second base bracket (7). The side-swing drive assembly includes a side-swing smart electric cylinder (10), a first rotating base (8) and a second rotating base (9). The motor shaft of the side-swing smart electric cylinder (10) is connected to the first rotating base (8) and the second rotating base (9) on both sides respectively. The motor shaft of the side-swing smart electric cylinder (10) forms a side-swing shaft C to drive the first phalanx (1) and the second phalanx (4) of the thumb to rotate around the side-swing shaft C relative to the first rotating base (8) and the second rotating base (9). The rotary drive assembly includes a rotary dexterous electric cylinder (12), a main drive gear (13), and a driven gear disk (11). The main drive gear (13) is mounted on the motor shaft of the rotary dexterous electric cylinder (12). The main drive gear (13) meshes with the gear on the driven gear disk (11). The rotary dexterous electric cylinder (12) drives the driven gear disk (11) to rotate through the main drive gear (13), thereby driving the first phalanx of the thumb (1), the second phalanx of the thumb (4), and the side-swing drive assembly to rotate as a whole. The side-swinging dexterous electric cylinder (10) is mounted on the driven gear disk (11), the first base bracket (6) and the second base bracket (7) are respectively fixed on the first rotating base (8) and the second rotating base (9), and the rotating dexterous electric cylinder (12) is mounted on the dexterous hand body.

2. The multi-degree-of-freedom dexterous hand thumb structure according to claim 1, characterized in that, The first knuckle dexterous hand cylinder (3) is installed in the first knuckle (1) of the thumb in an inverted manner; The second knuckle dexterous hand cylinder (5) is installed in the second knuckle of the thumb (4) in an inverted manner.

3. The multi-degree-of-freedom dexterous hand thumb structure according to claim 1, characterized in that, A tactile sensor (2) is integrated at the tip of the first phalanx (1) of the thumb.

4. The multi-degree-of-freedom dexterous hand thumb structure according to claim 1, characterized in that, The motor shaft of the second knuckle-operated dexterous electric cylinder (5) is connected to the first base bracket (6) and the second base bracket (7) respectively by screws on both sides; The motor shaft of the side-swinging dexterous electric cylinder (10) is connected to the first rotating base (8) and the second rotating base (9) respectively by screws.

5. The multi-degree-of-freedom dexterous hand thumb structure according to claim 1, characterized in that, The main drive gear (13) is fixed to the motor shaft of the rotary dexterous hand cylinder (12) by screws.

6. The multi-degree-of-freedom dexterous hand thumb structure according to claim 1, characterized in that, The side-swinging dexterous electric cylinder (10) is fixed above the driven gear disk (11). A bearing (14) is interference-fitted onto the cylinder below the driven gear disk (11). The driven gear disk (11) is rotatably connected to the bearing hole on the dexterous hand body through the bearing (14). The bearing (14) serves as a rotation center and provides support.

7. A control method for a multi-degree-of-freedom dexterous hand thumb structure, applied to the multi-degree-of-freedom dexterous hand thumb structure as described in any one of claims 1 to 6, characterized in that, include: Control the first knuckle dexterous electric cylinder (3) to work, drive the first knuckle (1) of the thumb to rotate relative to the second knuckle (4) of the thumb around the first knuckle rotation axis A through its motor shaft, so as to realize the bending movement of the first knuckle; The second knuckle dexterous electric cylinder (5) is controlled to work, and the second knuckle (4) of the thumb is driven to rotate around the second knuckle rotation axis B relative to the first base bracket (6) and the second base bracket (7) through its motor shaft, so as to realize the bending movement of the second knuckle; The side-swinging dexterous electric cylinder (10) is controlled to work, and the first phalanx (1) and the second phalanx (4) of the thumb are driven to rotate around the side-swinging axis C relative to the first rotating base (8) and the second rotating base (9) through its motor shaft, so as to realize the side-swinging movement of the thumb; The rotating dexterous electric cylinder (12) is controlled to work, and its motor shaft drives the main drive gear (13) to rotate and drive the driven gear disk (11) to rotate, thereby realizing the overall rotational movement of the thumb.

8. The control method for the thumb structure of a multi-degree-of-freedom dexterous hand according to claim 7, characterized in that, The method further includes: Acquire tactile signals collected by tactile sensor (2); Adjust the output torque of the first knuckle dexterous hand cylinder (3) and / or the second knuckle dexterous hand cylinder (5) according to the tactile signal.

9. The control method for the thumb structure of a multi-degree-of-freedom dexterous hand according to claim 7, characterized in that, The first knuckle bending motion, the second knuckle bending motion, the thumb side swing motion, and the thumb overall rotation motion are independently driven and controlled by the first knuckle dexterous electric cylinder (3), the second knuckle dexterous electric cylinder (5), the side swing dexterous electric cylinder (10), and the rotation dexterous electric cylinder (12), respectively.

10. The control method for the thumb structure of a multi-degree-of-freedom dexterous hand according to claim 7, characterized in that, The method further includes: Based on the target grasping posture, determine the target rotation angle of each of the first knuckle dexterous electric cylinder (3), the second knuckle dexterous electric cylinder (5), the side-swing dexterous electric cylinder (10), and the rotating dexterous electric cylinder (12); The motor shafts of the first knuckle dexterous electric cylinder (3), the second knuckle dexterous electric cylinder (5), the side-swing dexterous electric cylinder (10), and the rotary dexterous electric cylinder (12) are respectively controlled to rotate to their respective target rotation angles.

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