Multi-degree-of-freedom dexterous hand based on force position control and control method thereof

Abstract

The invention discloses a multi-degree-of-freedom dexterous hand based on force and position control and a control method thereof, belongs to the technical field of industrial robots and automation, and solves the problems that in the prior art, a dexterous hand is limited in flexibility, lacks a feedback system, is low in control precision and is high in design cost. The robot comprises a palm and a plurality of fingers, finger joints are provided with angle sensors, grasping surfaces are provided with pressure sensors, the angle sensors and the pressure sensors are connected with an external control system, the control method comprises six steps of task planning and the like, and accurate operation is achieved. Through multi-joint design, sensing feedback and force-position hybrid control, the flexibility and control precision of the dexterous hand are improved, the production and maintenance cost is reduced through the modular structure, the dexterous hand can adapt to complex industrial scenes, the high-precision and high-stability operation requirements are met, and the efficiency is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of industrial robots and automation technology, and in particular to a multi-degree-of-freedom dexterous hand based on force-position control and a control method thereof. Background Art

[0002] With the development of industrial automation, industrial dexterous hands are increasingly being used in manufacturing, assembly, and handling. While existing industrial dexterous hands can perform basic repetitive operations, their flexibility and precision are often limited, making them incapable of complex and delicate tasks. Furthermore, most dexterous hands lack real-time feedback capabilities in their control systems, making it difficult to adapt in dynamic environments. Consequently, existing technologies suffer from the following deficiencies: 1. Limited flexibility; 2. Lack of feedback system; 3. Low control accuracy.

[0003] Therefore, there is an urgent need for a multi-degree-of-freedom, high-precision industrial dexterous hand to adapt to the high-demand scenarios in modern production.

[0004] Most dexterous hands lack real-time feedback capabilities in their control systems, making it difficult to adapt in dynamic environments. Existing technologies therefore suffer from the following deficiencies: Limited flexibility: Most industrial dexterous hands lack multi-degree-of-freedom designs, making complex posture adjustments difficult. Lacking a feedback system, existing dexterous hands react slowly to changes in the external environment and lack the ability to adjust in real time. Control accuracy is low, and due to the limitations of existing control systems, high-precision operations are difficult to achieve. Furthermore, existing dexterous hands are expensive to design, making them difficult to meet the demands of cost-effective industrial production. Summary of the Invention

[0005] The present invention proposes a multi-degree-of-freedom dexterous hand based on force-position control. Through multi-joint modular structure design, integrated flexible sensing system and application of hybrid control algorithm, it solves the problems of limited flexibility, lack of feedback system, low control accuracy and high design cost of dexterous hands in the existing technology.

[0006] A multi-degree-of-freedom dexterous hand based on force-position control, comprising a palm and multiple fingers, wherein the multiple fingers are rotatably connected to the edge of the palm, and characterized in that an angle sensor is installed at the joint of each finger, and a pressure sensor is installed on the gripping surface of each finger, and both the angle sensor and the pressure sensor are connected to the external control system signal.

[0007] Furthermore, the plurality of fingers includes a thumb and four ordinary fingers, Each common finger includes a finger base joint, a proximal phalanx shell, a middle phalanx shell, and a fingertip. The palm is fixedly connected to one end of the finger base joint, and the other end of the finger base joint is rotatably connected to the proximal phalanx shell, the middle phalanx shell, and the fingertip in sequence. The thumb includes a thumb base joint, a proximal phalanx shell and a fingertip. One end of the thumb base joint is rotatably connected to the palm, and the other end of the thumb base joint, the proximal phalanx shell and the fingertip are rotatably connected in sequence. A driving unit is provided in each of the palm, the proximal phalanx housing and the middle phalanx housing. The driving unit includes a servo motor and a reducer. The output end of the servo motor is fixedly connected to the input end of the reducer.

[0008] Furthermore, an upper drive unit and a lower drive unit are installed in the proximal phalanx shell, and the upper drive unit and the lower drive unit are respectively installed in the upper and lower parts of the proximal phalanx shell. The output end of the reducer in the lower drive unit is fixedly connected to the upper end of the finger base joint or the thumb base joint, and the output end of the reducer in the upper drive unit is fixedly connected to the lower end of the middle phalanx shell.

[0009] Furthermore, a set of drive units is installed in the middle phalanx shell, and the set of drive units is installed in the upper part of the middle phalanx shell. The output end of the reducer in the set of drive units is fixedly connected to the lower end of the fingertip. The output end of the speed reducer located at the upper part of the proximal knuckle housing is fixedly connected to the lower part of the middle knuckle housing.

[0010] Furthermore, the middle phalanx shell includes a left middle phalanx shell and a right middle phalanx shell, the opening sides of the left middle phalanx shell and the right middle phalanx shell are relatively fixedly connected, and the proximal phalanx shell includes two parts with the same structure, and the opening sides of the two parts with the same structure are reversed, fitted and fixedly connected.

[0011] Furthermore, a set of drive units is fixedly installed in the palm corresponding to the base joint of the thumb. The output end of the reducer in the set of drive units is fixedly connected to the lower end of the base joint of the thumb, driving the thumb to rotate in the plane where the palm is located.

[0012] Furthermore, the output end of the reducer is a D-shaped worm, and the lower end of the fingertip, the lower end of the middle finger joint shell, the upper end of the finger base joint and the upper and lower ends of the thumb base joint are all provided with D-shaped through holes, which are tightly fitted and fixedly connected with the D-shaped worm.

[0013] Furthermore, pressure sensors are installed on the proximal knuckle housing, the middle knuckle housing and the fingertips, and an angle sensor is installed on the D-shaped worm of each reducer.

[0014] Furthermore, the external control system is electrically connected to the driving unit to control the movement of the driving unit.

[0015] A control method for a multi-degree-of-freedom dexterous hand based on force-position control is applied to the above-mentioned multi-degree-of-freedom dexterous hand based on force-position control. The driving method of the multi-degree-of-freedom dexterous hand comprises the following steps: S1. Determine the motion target and operation parameters of the dexterous hand based on the preset operation task, complete high-level task decomposition and path planning, and provide basic instructions for subsequent control; S2. Based on the task planning results, the motion trajectory of each joint of the dexterous hand is planned to ensure smooth and controllable motion and avoid shock or vibration caused by sudden speed changes during operation. S3, collecting contact force information and the motion state of each joint of the dexterous hand through pressure sensors and angle sensors, fusing the collected information, and generating feedback data for control; S4. Based on the fused feedback data, a force-position hybrid control strategy is adopted to coordinate the position and contact force of the dexterous hand, and the weights of position control and force control are dynamically adjusted according to the operation stage. S5. Perform closed-loop feedback control on the contact force, and dynamically adjust the control signal according to the deviation between the target contact force and the actual contact force, so that the actual contact force converges to the target value; S6. The generated control signal is transmitted to the driving unit of the dexterous hand, driving each joint to move according to the planned trajectory and control requirements to complete the preset operation task.

[0016] Beneficial effects of the present invention: The multi-degree-of-freedom dexterous hand based on force-position control and the control method thereof of the present invention have a multi-joint design that makes the dexterous hand highly flexible, capable of complex posture adjustments and fine operations, and can flexibly complete complex actions such as grasping and releasing to adapt to the requirements of different industrial tasks; the equipped intelligent control system is combined with a flexible sensing system, which can receive sensor feedback information in real time and adjust the action, and improves the response speed and control accuracy through multi-sensor data fusion, realizing precise control, which is suitable for industrial precision tasks; at the same time, the dexterous hand adopts a modular structural design, each module contains standardized drive units and joints, which can be reused between different models, and the drive system integrating the motor and transmission device reduces the number of parts and assembly time, significantly reducing production and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 Schematic diagram of the structure of a multi-degree-of-freedom dexterous hand based on force-position control according to the present invention; Figure 2 for Figure 1 Enlarged view of point A in the middle; Figure 3 Schematic diagram of the structure of a common finger; Figure 4 for Figure 3 Exploded diagram; Figure 5 Schematic diagram of the cross-sectional structure of an ordinary finger; Figure 6 for Figure 5 Enlarged view of point B in the middle; Figure 7 Schematic diagram of controller layering strategy; Figure 8 Schematic diagram of force position control strategy; Figure 9 This is the block diagram of the contact force feedback control algorithm; Figure 10 Schematic diagram of force analysis of the target object.

[0017] Among them, 1 is the fingertip, 2 is the pressure sensor, 3 is the angle sensor, 4 is the left shell of the middle phalanx, 5 is the right shell of the middle phalanx, 6 is the shell of the proximal phalanx, 7 is the base joint of the finger, 8 is the palm, 9 is the base joint of the thumb, 10 is the reducer, and 11 is the servo motor. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0019] Reference Figures 1-10 As shown, a multi-degree-of-freedom dexterous hand based on force-position control includes a palm 8 and multiple fingers, and the multiple fingers are rotatably connected to the edge of the palm 8. It is characterized in that an angle sensor 3 is installed at the joint of each finger, and a pressure sensor 2 is installed on the gripping surface of each finger. The angle sensor 3 and the pressure sensor 2 are both connected to the external control system signal.

[0020] Specifically, the multi-degree-of-freedom dexterous hand based on force-position control described in this embodiment achieves real-time and precise monitoring of the motion state of each joint and the gripping contact force of the dexterous hand by installing angle sensors at the joints of each finger and pressure sensors on the gripping surface, and connecting both to the external control system signal. This design enables the external control system to timely obtain the angle changes of finger movement and the force conditions of contact with objects, providing comprehensive and reliable feedback data for subsequent precise control, effectively solving the problems of limited flexibility and low control accuracy caused by the lack of real-time feedback in existing dexterous hands. The real-time capture of joint angles by angle sensors, combined with the dynamic perception of contact forces by pressure sensors, allows the dexterous hand to adjust its movements in a timely manner based on feedback information when performing complex industrial operations. This not only improves the flexibility and adaptability of operations, making it capable of performing delicate grasping, assembly and other tasks, but also enhances the stability of operations through the real-time feedback mechanism, avoiding damage to objects or operational errors caused by improper force or angle deviation, and overall meets the demand for highly flexible and high-precision dexterous hands in modern industrial production.

[0021] Furthermore, the plurality of fingers includes a thumb and four ordinary fingers, Each common finger includes a finger base joint 7, a proximal phalanx shell 6, a middle phalanx shell and a fingertip 1. The palm 8 is fixedly connected to one end of the finger base joint 7, and the other end of the finger base joint 7 is rotatably connected to the proximal phalanx shell 6, the middle phalanx shell and the fingertip 1 in sequence. The thumb includes a thumb base joint 9, a proximal phalanx shell 6 and a fingertip 1. One end of the thumb base joint is rotatably connected to the palm 8, and the other end of the thumb base joint 9, the proximal phalanx shell 6 and the fingertip 1 are rotatably connected in sequence. A driving unit is provided in the palm 8 , the proximal phalanx housing 6 and the middle phalanx housing. The driving unit includes a servo motor 11 and a reducer 10 . The output end of the servo motor 11 is fixedly connected to the input end of the reducer 10 .

[0022] Specifically, the multi-degree-of-freedom dexterous hand based on force-position control described in this embodiment is constructed by dividing the fingers into the thumb and four ordinary fingers, and designing adaptive structural components for each of them. The ordinary fingers are connected to the finger base joint 7, the proximal phalanx shell 6, the middle phalanx shell and the fingertip 1 in sequence, and the thumb is connected to the thumb base joint 9, the proximal phalanx shell 6 and the fingertip 1 in sequence. At the same time, a drive unit including a servo motor 11 and a reducer 10 is set in the palm 8, the proximal phalanx shell 6 and the middle phalanx shell, thereby achieving reasonable partitioning of the dexterous hand structure and precise power transmission. This design not only ensures the independence and flexibility of the movement of each finger, allowing ordinary fingers to complete complex multi-joint linkage movements, and the thumb can flexibly rotate within the plane of the palm 8 to adapt to different grasping scenarios, but also provides stable and controllable driving force for each joint through the cooperation of the servo motor 11 and the reducer 10, ensuring the accuracy of movement and torque output, and effectively solving the problems of insufficient flexibility and low power transmission efficiency of existing dexterous hands. In addition, the modular structure facilitates assembly and maintenance. The orderly connection of various components and the built-in design of the power unit not only optimize the overall layout of the dexterous hand, but also improves its adaptability and reliability in performing tasks such as grasping and assembly in industrial scenarios, meeting the high-precision and high-flexibility operation requirements.

[0023] Furthermore, an upper drive unit and a lower drive unit are installed in the proximal phalanx shell 6, and the upper drive unit and the lower drive unit are respectively installed in the upper and lower parts of the proximal phalanx shell 6. The output end of the reducer 10 in the lower drive unit is fixedly connected to the upper end of the finger base joint 7 or the thumb base joint 9, and the output end of the reducer 10 in the upper drive unit is fixedly connected to the lower end of the middle phalanx shell.

[0024] Specifically, in this embodiment, an upper drive unit and a lower drive unit are disposed within the proximal phalanx housing 6, and are mounted at the upper and lower portions of the housing 6, respectively. The output end of the reducer 10 of the lower drive unit is fixedly connected to the upper end of the base joint 7 of the finger or the base joint 9 of the thumb, while the output end of the reducer 10 of the upper drive unit is fixedly connected to the lower end of the housing 6 of the middle phalanx. This structural design enables precise drive and coordinated control of the proximal phalanx itself and subsequent joints. The independent layout of the upper and lower drive units not only ensures the flexible rotation of the proximal phalanx relative to the base joint, but also provides independent power sources for the movement of the middle phalanx and fingertip 1. This allows for the movement of each finger segment to be independent of each other and precisely controlled, significantly enhancing the finger's multi-degree-of-freedom motion capability and enabling more complex bending and extension movements to accommodate the grasping needs of objects of varying shapes and sizes. At the same time, this built-in drive unit layout optimizes the utilization of the internal space of the finger, reduces the redundancy of the external structure, makes the overall structure more compact, and cooperates with the stable output of the servo motor 11 and the reducer 10 to further enhance the stability and accuracy of the movement, effectively overcoming the problems of limited flexibility and low power transmission efficiency caused by unreasonable drive layout in existing dexterous hands.

[0025] Furthermore, a set of drive units is installed in the middle phalanx shell, and the set of drive units is installed in the upper part of the middle phalanx shell. The output end of the reducer 10 in the set of drive units is fixedly connected to the lower end of the fingertip 1. The output end of the speed reducer 10 located at the upper portion of the proximal phalanx housing 6 is fixedly connected to the lower portion of the middle phalanx housing.

[0026] Specifically, this embodiment incorporates a set of drive units within the upper portion of the middle phalanx housing, with the output end of its reducer 10 fixedly connected to the lower end of the fingertip 1. Simultaneously, the output end of the reducer 10 located above the proximal phalanx housing 6 is fixedly connected to the lower portion of the middle phalanx housing, forming a precise power transmission chain from the proximal phalanx to the middle phalanx and then to the fingertip 1. This design allows the middle phalanx to rotate independently driven by the proximal phalanx while independently driving the fingertips to perform movements such as bending, making multi-joint finger movements more coordinated and controllable. This significantly enhances the flexibility and precision of fingertip manipulation, allowing for the grasping and delicate manipulation of objects of varying shapes and sizes. The layered layout of the drive units not only fully utilizes the internal space within the phalanx, resulting in a more compact structure, but also ensures stable power transmission through the rigid connection between the reducer 10 and the various components, preventing looseness or lag during movement. This effectively addresses the issues of insufficient precision and poor coordination associated with discontinuous power transmission in existing dexterous hands, further enhancing their adaptability and reliability in scenarios such as industrial assembly and material handling, and ensuring the efficient completion of complex manipulation tasks.

[0027] Furthermore, the middle phalanx shell includes a left middle phalanx shell 4 and a right middle phalanx shell 5, the opening sides of which are relatively fixedly connected, and the proximal phalanx shell 6 includes two parts with the same structure, and the opening sides of the two parts with the same structure are reversed, fitted and fixedly connected.

[0028] Specifically, this embodiment divides the middle phalanx housing into a left phalanx housing 4 and a right phalanx housing 5, with their open sides fixedly connected relative to each other. Meanwhile, the proximal phalanx housing 6 is designed as two identical parts that are reversed and fixed together. This split housing design not only facilitates the installation and commissioning of internal components such as the drive unit and sensors, but also ensures the overall structural strength and sealing of the housing through precise fitting, preventing the ingress of dust and impurities that could affect the operation of internal components. The coordinated operation of the left and right phalanx housings allows the right housing to stably house the reduction motor, while the left housing reliably secures the motor and provides space for the sensor and wiring. The symmetrical design of the proximal phalanx housing 6 simplifies processing, reduces manufacturing costs, and facilitates quick disassembly for component replacement or overhaul when maintenance is required. This structure not only optimizes the utilization of the internal space of the phalanx, ensuring a compact and orderly layout of components, but also improves the maintainability and economical production of the dexterous hand, effectively resolving the assembly difficulties, maintenance difficulties, and high manufacturing costs associated with the integrated housing structure of existing dexterous hands.

[0029] Furthermore, a set of drive units is fixedly installed in the palm 8 corresponding to the thumb base joint 9, and the output end of the reducer 10 in the set of drive units is fixedly connected to the lower end of the thumb base joint 9, driving the thumb to rotate in the plane where the palm 8 is located.

[0030] Specifically, this embodiment achieves independent and precise control of the thumb's rotation within the plane of the palm 8 by fixedly installing a drive unit at the location corresponding to the thumb base joint 9 in the palm 8 and fixedly connecting the output end of the reducer 10 in the drive unit to the lower end of the thumb base joint 9. This design allows the thumb to flexibly adjust its position and angle within the plane of the palm 8, actively adapting to the coordination relationship with other fingers based on the shape and size of the grasped object, greatly expanding the grasping range and adaptability of the dexterous hand. Whether grasping small precision parts or larger objects, the flexible rotation of the thumb can form a stable grasping posture. At the same time, the direct connection between the drive unit and the thumb base joint 9 ensures efficient and stable power transmission, enabling rapid thumb rotation response and precise angle control, avoiding coordination errors caused by transmission lag or looseness, and effectively solving the problem of insufficient thumb flexibility and difficulty in adapting to complex grasping scenarios in existing dexterous hands.

[0031] Furthermore, the output end of the reducer 10 is a D-shaped worm, and the lower end of the fingertip 1, the lower end of the middle finger joint shell, the upper end of the finger base joint 7 and the upper and lower ends of the thumb base joint 9 are all provided with D-shaped through holes, which are tightly fitted and fixedly connected with the D-shaped worm.

[0032] Furthermore, this embodiment utilizes a D-shaped worm gear at the output end of the reducer 10 and correspondingly provides D-shaped through-holes at the lower end of the fingertip 1, the lower end of the middle phalanx housing, the upper end of the finger base joint 7, and the upper and lower ends of the thumb base joint 9. The non-circular nature of the D-shaped structure allows for a tight, secure connection. This design ensures a rigid connection and precise positioning during power transmission, effectively avoiding the relative rotation or slippage that can occur with traditional circular connections. This allows for efficient and lossless transmission of driving torque from the reducer to each joint and phalanx, ensuring the synchronization and accuracy of the movement of each component. Furthermore, the D-shaped fitting structure simplifies the assembly process, eliminating the need for additional locating pins or fasteners to achieve a reliable connection. This reduces assembly difficulty, the number of components, and helps control overall weight and manufacturing costs. Furthermore, this connection method facilitates disassembly and replacement during subsequent maintenance. If a component fails, it can be quickly detached and replaced, improving the maintainability of the dexterous hand and overall enhancing the stability and durability of the device in long-term industrial applications, better meeting the requirements of high-precision, high-reliability operation.

[0033] Furthermore, pressure sensors 2 are installed on the proximal phalanx housing 6 , the middle phalanx housing and the fingertips 1 , and angle sensors 3 are installed on the D-shaped worm of each reducer 10 .

[0034] Specifically, this embodiment achieves comprehensive and accurate monitoring of the contact force between the dexterous hand and the object, as well as the movement angles of each joint, by installing pressure sensors 2 on the proximal phalanx housing 6, the middle phalanx housing, and the fingertips 1, and installing angle sensors 3 on the D-shaped worm gear of each reducer 10. The pressure sensors 2 on the fingertips can capture the force applied to each knuckle in real time, ensuring that the force applied during grasping is controllable and preventing damage to the object due to excessive force or loss of the object due to insufficient force. The angle sensors 3 on the D-shaped worm gear of the reducer can accurately track the rotation angle of each joint, providing data support for precise control of the finger's movement trajectory. The layout design and functional coordination of this sensor enable the external control system to obtain real-time feedback of contact force and joint angle at the same time, providing a comprehensive and reliable basis for subsequent force-position hybrid control. It effectively solves the problems of control lag and poor operational stability caused by incomplete or insufficient sensor information in existing dexterous hands. When performing complex industrial tasks such as grasping and assembly, the dexterous hand can not only ensure the accuracy of movement angle but also flexibly adjust the contact force, significantly improving the adaptability and reliability of the operation, and better meeting the needs of modern industrial production for high-precision and high-stability dexterous hands.

[0035] Furthermore, the external control system is electrically connected to the driving unit to control the movement of the driving unit.

[0036] A control method for a multi-degree-of-freedom dexterous hand based on force-position control is applied to the above-mentioned multi-degree-of-freedom dexterous hand based on force-position control. The driving method of the multi-degree-of-freedom dexterous hand comprises the following steps: S1. Determine the motion target and operation parameters of the dexterous hand based on the preset operation task, complete high-level task decomposition and path planning, and provide basic instructions for subsequent control; S2. Based on the task planning results, the motion trajectory of each joint of the dexterous hand is planned to ensure smooth and controllable motion and avoid shock or vibration caused by sudden speed changes during operation. S3, collecting contact force information of the dexterous hand and the motion state of each joint through the pressure sensor 2 and the angle sensor 3, fusing the collected information and generating feedback data for control; S4. Based on the fused feedback data, a force-position hybrid control strategy is adopted to coordinate the position and contact force of the dexterous hand, and the weights of position control and force control are dynamically adjusted according to the operation stage. S5. Perform closed-loop feedback control on the contact force, and dynamically adjust the control signal according to the deviation between the target contact force and the actual contact force, so that the actual contact force converges to the target value; S6. The generated control signal is transmitted to the driving unit of the dexterous hand, driving each joint to move according to the planned trajectory and control requirements to complete the preset operation task.

[0037] Specifically, this embodiment forms a complete and coordinated control logic by sequentially executing the steps of task planning, trajectory planning, sensor data acquisition and fusion, force-position hybrid control, contact force closed-loop adjustment and drive execution, ensuring that the dexterous hand can efficiently and accurately complete the preset operation tasks. First, the operation goal is clarified through high-level task decomposition and path planning, providing a clear direction for subsequent control; the smooth trajectory based on this plan effectively avoids motion impact and ensures the stability of the operation; and the fusion processing of sensor data provides a comprehensive and reliable feedback basis for control decisions, enabling the system to grasp the finger movement state and contact force in real time; the force-position hybrid control strategy dynamically adjusts the weights of position and force control according to the operation stage, achieving the coordinated optimization of position accuracy and contact force stability; the closed-loop adjustment of contact force further ensures that the actual force converges to the target value, avoiding the problem of grasping too loose or too tight; finally, the control signal is converted into precise action through the drive unit to complete the operation task. This control method effectively solves the problems of response lag, insufficient precision, and poor adaptability in existing dexterous hand control, enabling the dexterous hand to flexibly respond to different operating tasks in complex industrial scenarios while maintaining high precision and high stability. It significantly improves its reliability and efficiency in tasks such as grasping and assembly, and meets the high requirements of modern industrial production for the control performance of dexterous hands.

[0038] Specific examples of the present invention are as follows: In response to the above problems, the present invention aims to provide a multi-degree-of-freedom industrial dexterous manipulator, which achieves simple structure, high flexibility and precise control through an innovatively designed multi-joint structure, flexible sensing system and force-position control module.

[0039] In the first aspect, the finger portion of the dexterous hand of the present invention mainly includes a proximal phalanx structure, a middle phalanx structure and a fingertip. The proximal phalanx structure is connected to the palm through a base joint, and the middle phalanx structure is rotationally connected to the reducer of the proximal phalanx through the right shell of the middle phalanx. The palm portion is connected to a plurality of finger portions, each finger portion is composed of a joint and a plurality of phalanxes, and the fingertip and middle phalanx each contain a joint. The three parts of the dexterous hand fingers (proximal phalanx, middle phalanx and fingertip) can be structurally separated, thereby enhancing the adaptability and maintainability of the dexterous hand. By adopting a multi-degree-of-freedom design, the dexterous hand can flexibly perform complex posture adjustments and fine operations to meet the requirements of different industrial tasks. The modular design of all joints and phalanxes allows the dexterous hand to be customized and optimized according to the requirements of different tasks, thereby reducing production and maintenance costs.

[0040] According to the first aspect, the palm part is mainly used to connect the thumb and the four fingers, and is equipped with a drive unit that drives the movement of the thumb. The palm is connected to the thumb part through the thumb base joint, and is connected to the four finger parts through the four finger base joints. The drive mechanisms of the finger parts are all installed in the knuckle shells, and each knuckle is equipped with an independent drive unit. The middle knuckle part includes a left knuckle shell, a right knuckle shell, a servo motor and a reducer. The drive unit of the middle knuckle mainly drives the rotation of the fingertips, so that the fingertips can bend and operate accurately when grasping objects. The proximal knuckle part includes two identical proximal knuckle shells, two servo motors and two reducers. The two drive units of the proximal knuckle part respectively drive the rotation of the proximal knuckle and the rotation of the middle knuckle, thereby achieving more flexible operation.

[0041] According to the first aspect, the proximal phalanx of the thumb is the same as the proximal phalanx of other fingers, except that the other side of the base joint of the thumb is connected to another drive unit for controlling the rotation of the thumb part in the palm plane, making the thumb more flexible during grasping. According to the first aspect, a D-shaped through hole with a diameter of 3mm is designed in the fingertip part, which is used to cooperate with the D-shaped worm at the output end of the reducer to provide power for the fingertip part. The middle phalanx part has a built-in drive unit for driving the distal joint to achieve fingertip bending movement. The middle phalanx shell is divided into two parts. The reduction motor is placed in the right shell of the middle phalanx, and the bottom is fixed to the middle joint. The joint is designed with a D-shaped through hole to transmit power; the left shell of the middle phalanx is used to fix the motor, and holes are designed to install angle sensors and arrange wires. Two drive units are built into the proximal phalanx part to drive the bending movement of the middle joint and proximal joint. The proximal phalanx shell is divided into two parts with the same structure. The motor fixing position and sensor installation position are designed on the shell respectively. The two parts are reversed, fitted and fixed.

[0042] According to the first aspect, the present invention adopts a design concept that integrates joints and transmission components, reducing the number of mechanical parts and simplifying the assembly process. The drive unit of each joint integrates a motor and a transmission device, reducing the number of parts. When a problem occurs in a certain part of the mechanical components, workers only need to disassemble the problematic component and replace it with a new one to solve the problem. In addition, the modular design allows the various parts of the dexterous hand to be customized and optimized according to the requirements of different tasks, which significantly improves the working efficiency of the dexterous hand.

[0043] Secondly, each finger contains three angle sensors and three pressure sensors, while the thumb contains three angle sensors and two pressure sensors. Each joint is equipped with an angle sensor to monitor changes in joint angle in real time. Each knuckle is equipped with a pressure sensor at the point of contact with an object to monitor changes in force applied to the knuckle in real time. These sensors not only provide accurate feedback on the joint's state but also sense the contact force of external objects, providing the necessary feedback data to the control system, enabling real-time monitoring and adjustment of finger movements.

[0044] According to the second aspect, each angle sensor cooperates with the D-shaped worm gear at the output end of the reducer, rotates along with the rotation of the fingertip joint, and can monitor the changes in the joint angle in real time. In the proximal phalanx, the angle sensor connected to the base joint monitors the rotation angle of the proximal phalanx, and the angle sensor connected to the middle phalanx detects the rotation angle of the middle phalanx. In the middle phalanx, its angle sensor monitors the rotation angle of the fingertip. When grasping an object, each phalanx is equipped with a pressure sensor at the position where it contacts the object, which is used to monitor the force applied to the grasped object in real time.

[0045] According to the second aspect, the present invention adopts a hierarchical control structure, which is divided into high-level task planning, middle-level force and position control, and low-level execution control, and each layer works together to achieve precise control.

[0046] According to the second aspect, the control system of the present invention is able to receive sensor feedback information in real time and accurately control the operating state of each drive unit based on the angle, force, and position changes of each joint and knuckle. Through a multi-sensor weighted fusion algorithm, the data from the angle sensor, pressure sensor, and position sensor are fused to generate high-precision joint angle, contact force, and position feedback signals. The real-time feedback and adaptive adjustment capabilities of the control system enable the dexterous hand to respond flexibly in complex environments, achieving higher operational accuracy and adaptability.

[0047] According to a second aspect, the position control module uses PID control, and the force control module uses impedance control. The position control module tracks the target position, and the force control module adjusts the contact force. The weights of position control and force control are dynamically adjusted according to the mission stage and environmental changes.

[0048] According to the second aspect, the multi-sensor weighted fusion algorithm dynamically assigns weights and integrates joint angles and contact forces to achieve stable grasping of the dexterous hand under the force / position hybrid control framework. The weighted fusion model is:

[0049] in, ,The weight distribution needs to be dynamically adjusted according to the control stage and ,contact state. : Controller gains for joint angles and contact forces. : Total contact force.

[0050] During the position control phase:

[0051] : Upper limit of sensor range. Smooth transition coefficient.

[0052] In the force control phase:

[0053] : Maximum allowable error of joint angle. : Position error influence coefficient.

[0054] During the position control phase, when the contact force is close to zero , completely dependent on joint angle tracking. In the contact transition phase, as the contact force increases, Gradually increase to achieve smooth switching. In the force control stage, if the joint angle error is small ( ), , completely dependent on force control.

[0055] According to the second aspect, in the first stage of the dexterous hand grasping the target object, directly controlling the joint angle to reach the target position at the maximum speed will lead to the following problems: 1. The speed at the moment the finger end contacts the object is too high, generating an instantaneous impact force, which may damage the object (such as brittle materials) or the internal transmission mechanism of the dexterous hand. 2. Sudden stops or rapid speed changes of the joints cause mechanical vibrations, reducing control accuracy. 3. Frequent starting and stopping of the motor increases energy consumption and shortens the life of the system. Therefore, smooth motion is required through trajectory planning to ensure that the finger approaches the target at a controllable speed and the speed is attenuated before contact. The position control is characterized in that the trajectory planning includes the following steps: calculating the target joint angle through inverse kinematics; generating a smooth trajectory in the joint space using a fifth-order polynomial interpolation; planning the end path using an S-shaped velocity curve in the Cartesian space; and adjusting the trajectory parameters online based on contact force feedback.

[0056] According to the second aspect, the present invention uses CFFCA (Contact Force Feedback Control Algorithm) to control the dexterous hand to grasp the target object. The grasping methods of the present invention include precise grasping and strong grasping. Precise grasping is also called fingertip grasping. In precise grasping, only the fingertips are in contact with the target object, the grasping dexterity is better, and it is suitable for grasping smaller objects. Strong grasping is also called envelope grasping. Both the phalanges and metacarpals are in contact with the target object, the grasping stability is better, and it is suitable for grasping larger objects. For envelope grasping, the distal phalanx, middle phalanx, proximal phalanx and metacarpal of the finger are in contact with the target object; for precise grasping, in single-finger precise grasping, only the distal phalanx and metacarpal are in contact with the target object, and at this time F i2 =F i3 =0, (i=1,2,3,4,5). In multi-finger precision grasping, only the distal phalanx touches the target object, and F i2 =F i3 =F i4 =0,(i=1,2,3,4,5).

[0057] According to the second aspect, the contact force feedback control algorithm achieves stable grasping through the following process: First, the minimum grasping force required is calculated based on the mass G and friction coefficient f of the target object. , to ensure that the object does not slip; then, the pressure sensors distributed on the dexterous fingers and metacarpal bones collect the force signals of each contact point in real time , and is summarized as the total contact force ΣF. The controller compares ΣF with Deviation , dynamically generate control signals. The algorithm uses an adaptive PID strategy to adjust the proportional and integral gains according to the error size and accumulated history ( ), to balance response speed and stability, while introducing dead zone threshold and speed limit to prevent oscillation. The DC motor receives the control signal Finally, the servo angle is adjusted by forward and reverse rotation to gradually converge the actual contact force to the target value, forming a closed-loop feedback.

[0058] Thirdly, the mechanical structure of the dexterous hand adopts a differentiated material selection design: the palm base, finger shell and joint connectors are made of carbon fiber reinforced composite materials (CFRP) to achieve an integrated lightweight configuration; transmission components such as joint bearings and gear sets are precision-cast using TC4 titanium alloy to ensure the structural strength of dynamic transmission; on the contact surface of the titanium alloy joint, a 50μm thick polyetheretherketone (PEEK) functional coating is covered by plasma spraying technology to form an interface strengthening layer.

[0059] According to the third aspect, CFRP, with its ultra-low density of 1.8-2.4g / cm³ and specific strength of 1500-2500MPa, reduces the weight of the finger module by 65% ​​compared to metal solutions while maintaining a load capacity of 300N. TC4 titanium alloy's 950MPa tensile strength and 0.02mm deformation tolerance under 10^7 cyclic loads give the joint long-term reliability against fatigue damage. PEEK coating achieves self-lubrication of the transmission interface and stability in low-temperature and high-temperature working conditions through a dynamic friction coefficient of 0.08-0.12 and an 87% wear rate reduction, ultimately achieving a comprehensive performance breakthrough of a system power-to-weight ratio of 1.2kW / kg and a transmission loss of less than 8%.

[0060] While the specific embodiments of the present invention have been described in detail above, these are intended to be exemplary only, and the present invention is not limited thereto. Any equivalent modifications or substitutions to the present invention that would be apparent to those skilled in the art are also within the scope of the present invention. Therefore, any equivalent modifications or substitutions made without departing from the spirit and scope of the present invention are intended to be encompassed within the scope of the present invention.

Claims

1. A multi-degree-of-freedom dexterous hand based on force-position control, the multi-degree-of-freedom dexterous hand based on force-position control comprising a palm (8) and a plurality of fingers, wherein the plurality of fingers are rotatably connected to the edge of the palm (8), characterized in that: An angle sensor (3) is installed at the joint of each finger, and a pressure sensor (2) is installed on the gripping surface of each finger. Both the angle sensor (3) and the pressure sensor (2) are connected to an external control system signal.

2. The multi-degree-of-freedom dexterous hand based on force-position control according to claim 1, characterized in that: Multiple fingers include the thumb and four ordinary fingers, Each common finger comprises a finger base joint (7), a proximal phalanx shell (6), a middle phalanx shell and a fingertip (1); the palm (8) is fixedly connected to one end of the finger base joint (7); and the other end of the finger base joint (7) is rotatably connected to the proximal phalanx shell (6), the middle phalanx shell and the fingertip (1) in sequence; The thumb includes a thumb base joint (9), a proximal phalanx shell (6) and a fingertip (1). One end of the thumb base joint is rotatably connected to the palm (8), and the other end of the thumb base joint (9), the proximal phalanx shell (6) and the fingertip (1) are rotatably connected in sequence. A drive unit is provided in each of the palm (8), the proximal phalanx housing (6), and the middle phalanx housing. The drive unit comprises a servo motor (11) and a reducer (10). The output end of the servo motor (11) is fixedly connected to the input end of the reducer (10).

3. The multi-degree-of-freedom dexterous hand based on force-position control according to claim 2, characterized in that: An upper drive unit and a lower drive unit are installed in the proximal phalanx housing (6), and the upper drive unit and the lower drive unit are respectively installed in the upper and lower parts of the proximal phalanx housing (6). The output end of the reducer (10) in the lower drive unit is fixedly connected to the upper end of the finger base joint (7) or the thumb base joint (9), and the output end of the reducer (10) in the upper drive unit is fixedly connected to the lower end of the middle phalanx housing.

4. The multi-degree-of-freedom dexterous hand based on force-position control according to claim 3, characterized in that: A set of drive units is installed in the middle phalanx shell, and the set of drive units is installed in the upper part of the middle phalanx shell. The output end of the reducer (10) in the set of drive units is fixedly connected to the lower end of the fingertip (1). The output end of the speed reducer (10) located at the upper part of the proximal phalanx housing (6) is fixedly connected to the lower part of the middle phalanx housing.

5. The multi-degree-of-freedom dexterous hand based on force-position control according to claim 4, characterized in that: The middle phalanx shell comprises a left middle phalanx shell (4) and a right middle phalanx shell (5), the opening sides of the left middle phalanx shell (4) and the right middle phalanx shell (5) being relatively fixedly connected, and the proximal phalanx shell (6) comprises two parts with the same structure, the opening sides of the two parts with the same structure being reversed, fitted and fixedly connected.

6. The multi-degree-of-freedom dexterous hand based on force-position control according to claim 5, characterized in that: A set of drive units is fixedly installed in the palm (8) at the position corresponding to the thumb base joint (9), and the output end of the reducer (10) in the set of drive units is fixedly connected to the lower end of the thumb base joint (9), driving the thumb to rotate in the plane where the palm (8) is located.

7. The multi-degree-of-freedom dexterous hand based on force-position control according to claim 6, characterized in that: The output end of the reducer (10) is a D-shaped worm, and the lower end of the fingertip (1), the lower end of the middle finger joint shell, the upper end of the finger base joint (7), and the upper end and lower end of the thumb base joint (9) are all provided with D-shaped through holes, and the D-shaped through holes are tightly matched with the D-shaped worm for fixed connection.

8. The multi-degree-of-freedom dexterous hand based on force-position control according to claim 7, characterized in that: Pressure sensors (2) are installed on the proximal knuckle housing (6), the middle knuckle housing, and the fingertips (1), and an angle sensor (3) is installed on the D-shaped worm of each reducer (10).

9. The multi-degree-of-freedom dexterous hand based on force-position control according to claim 8, characterized in that: The external control system is electrically connected to the driving unit to control the movement of the driving unit.

10. A control method for a multi-degree-of-freedom dexterous hand based on force-position control, applied to the multi-degree-of-freedom dexterous hand based on force-position control according to any one of claims 1 to 9, characterized in that: The driving method of the multi-degree-of-freedom dexterous hand comprises the following steps: S1. Determine the motion target and operation parameters of the dexterous hand based on the preset operation task, complete high-level task decomposition and path planning, and provide basic instructions for subsequent control; S2. Based on the task planning results, the motion trajectory of each joint of the dexterous hand is planned to ensure smooth and controllable motion and avoid shock or vibration caused by sudden speed changes during operation. S3, collecting contact force information of the dexterous hand and the motion state of each joint through the pressure sensor (2) and the angle sensor (3), fusing the collected information, and generating feedback data for control; S4. Based on the fused feedback data, a force-position hybrid control strategy is adopted to coordinate the position and contact force of the dexterous hand, and the weights of position control and force control are dynamically adjusted according to the operation stage. S5. Perform closed-loop feedback control on the contact force, and dynamically adjust the control signal according to the deviation between the target contact force and the actual contact force, so that the actual contact force converges to the target value; S6. The generated control signal is transmitted to the driving unit of the dexterous hand, driving each joint to move according to the planned trajectory and control requirements to complete the preset operation task.

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