An underwater dexterous hand driven by tendon rope

Abstract

A tendon-driven underwater dexterous hand relates to the technical field of underwater dexterous hands. In order to solve the technical problems existing in the prior art, that is, the existing operational underwater robots have a single grasping method and poor flexibility, and that conventional underwater manipulators are difficult to perform efficient and lossless adaptive grasping of underwater creatures, the present invention provides a technical solution: a tendon-driven underwater dexterous hand, comprising a palm, thumb, index finger, middle finger, ring finger and little finger, characterized in that: the index finger, middle finger, ring finger and little finger comprise: distal phalanx, middle phalanx and proximal phalanx, imitating human knuckles; the thumb comprises proximal phalanx and distal phalanx, imitating human knuckles; the palm imitates the shape of a human palm and is respectively connected to the proximal phalanx of the thumb, index finger, middle finger, ring finger and little finger. It is suitable for use in the work of achieving efficient and lossless adaptive grasping of underwater creatures through a manipulator.

Description

Technical Field

[0001] The invention relates to the technical field of underwater dexterous hands, and in particular to an underwater dexterous hand driven by a tendon rope. Background Art

[0002] With the rapid development of the global economy and the continuous increase in population, humanity's demand for resources is increasing. To address resource and energy challenges, humanity has begun exploring the oceans for survival and development. Ocean resources account for 71% of the world's total resources. To meet my country's strategic needs for exploring and developing marine resources and developing deep-sea operation technologies, and to further develop its fundamental strategy of becoming a maritime power, operational underwater robots have become a relatively effective means of underwater operations. They can replace traditional manual methods to meet the needs of deep-sea operations, enabling large-scale, continuous operations in the deep sea, more effectively developing marine resources, and meeting the needs of operations in complex environments.

[0003] At present, there are the following problems with operational underwater robots:

[0004] The end effector of an underwater robot mainly relies on a manipulator. Currently, common underwater manipulators are generally composed of two or three single-degree-of-freedom fingers. This type of manipulator has the disadvantages of a single grasping method and poor flexibility.

[0005] Conventional underwater robots equipped with actuators struggle to perform relatively complex underwater grasping tasks, depending on the specific needs of underwater operations. For example, when grasping underwater organisms, conventional underwater manipulators struggle to perform efficient, non-destructive adaptive grasping due to the diverse shapes and textures of these organisms. Summary of the Invention

[0006] To solve the technical problems existing in the prior art, that is, existing operational underwater robots have a single grasping method and poor flexibility, and that conventional underwater manipulators are difficult to perform efficient and non-destructive adaptive grasping of underwater organisms, the present invention provides the following technical solutions:

[0007] A tendon-driven underwater dexterous hand, comprising a palm, thumb, index finger, middle finger, ring finger and little finger, characterized in that:

[0008] The index finger, middle finger, ring finger and little finger include distal phalanx, middle phalanx and proximal phalanx, which imitate the human knuckles;

[0009] The thumb includes a proximal knuckle and a distal knuckle, imitating human knuckles;

[0010] The palm imitates the shape of a human palm and is respectively connected to the proximal knuckles of the thumb, index finger, middle finger, ring finger and little finger.

[0011] Furthermore, a preferred embodiment is provided, wherein the distal phalanx includes a distal phalanx, a six-axis force sensor and a fingertip pressure block, the six-axis force sensor is installed at the front end of the distal phalanx, and the fingertip pressure block is installed at the front end of the six-axis force sensor.

[0012] Furthermore, a preferred embodiment is provided, wherein the middle phalanx includes a middle phalanx and a distal joint, and the middle phalanx is connected to the distal phalanx via the distal joint.

[0013] Furthermore, a preferred embodiment is provided, wherein the distal joint comprises a sheave, a bearing and an end cover, wherein the sheave is arranged at the end of the middle phalanx, the bearing is installed in the sheave, and the end cover closes the distal joint.

[0014] Furthermore, a preferred embodiment is provided, wherein the proximal phalanx includes a proximal phalanx and a base joint, the proximal phalanx is connected to the middle phalanx via a middle joint, and the base joint has the freedom of bending and lateral swing relative to the palm.

[0015] Furthermore, a preferred embodiment is provided, further comprising a driving module, wherein the driving module is connected to the thumb, index finger, middle finger, ring finger and little finger via tendon cords.

[0016] Based on the same inventive concept, the present invention also provides a method for controlling a tendon-driven underwater dexterous hand. The method is implemented based on the aforementioned tendon-driven underwater dexterous hand and includes the following steps:

[0017] Perform system initialization and parameter preset steps;

[0018] The step of performing kinematic modeling on the dexterous hand;

[0019] The steps of collecting force and position data of each joint of the thumb, index finger, middle finger, ring finger and little finger in real time, filtering and denoising the data, and correcting model errors;

[0020] The step of obtaining a control signal according to the force and position data and outputting the control signal.

[0021] Based on the same inventive concept, the present invention also provides a computer storage medium for storing a computer program. When the computer program is read by a computer, the computer executes the method described above.

[0022] Based on the same inventive concept, the present invention also provides a computer, comprising a processor and a storage medium. When the processor reads the computer program stored in the storage medium, the computer executes the method described above.

[0023] Based on the same inventive concept, the present invention also provides a computer program product, which is a computer program. When the computer program is executed, the method described above is implemented.

[0024] Compared with the prior art, the technical solution provided by the present invention is beneficial in that:

[0025] The present invention provides a tendon-driven underwater dexterous hand. Through system initialization and parameter setting, the necessary libraries and drivers are loaded, initial parameters are set, and all components are properly connected, laying the foundation for subsequent precise control. This approach enables the dexterous hand to maintain stable performance in diverse environments and improves grasping flexibility. Compared to traditional underwater manipulators, this method can better adapt to the changing underwater environment.

[0026] This invention provides a tendon-driven underwater dexterous hand. Using the DH parameter method, a kinematic model is established through a kinematic modeling step to calculate the initial position and posture of each finger joint. This approach ensures the precision and coordination of finger movements, enabling the dexterous hand to perform complex grasping tasks. Compared to simplified models used in other studies, this method offers higher accuracy and reliability.

[0027] The present invention provides a tendon-driven underwater dexterous hand. Through sensor data acquisition and processing steps, force sensors and position sensors are activated to collect real-time force and position data from each finger joint. This data is then filtered and de-noised to ensure accuracy and stability. This approach enables real-time adjustments during the grasping process, preventing grasping failures due to data errors. Compared to other underwater manipulator systems that lack real-time correction capabilities, this solution significantly improves the grasping success rate.

[0028] The present invention provides a tether-driven underwater dexterous hand. Through a control algorithm execution step, it calculates control signals for each joint based on real-time sensor data. It then uses a PID control algorithm to adjust the motor drive, ensuring that the fingers follow a predetermined trajectory. This approach enables the dexterous hand to precisely control tether tension and joint angles for various grasping tasks, improving operational accuracy and flexibility. Compared to the simple control strategies used in traditional manipulators, this solution can handle more complex grasping tasks.

[0029] The present invention provides a tendon-driven underwater dexterous hand. Through a feedback adjustment and optimization process, the hand monitors sensor feedback data during the finger grasping process, analyzes the grasping effect, and adjusts control parameters based on this feedback to optimize grasping force and joint motion trajectory. This approach enables the dexterous hand to continuously optimize its performance across different tasks, improving grasping effectiveness. Compared to existing designs that lack feedback optimization, this solution can maintain efficient and stable performance over long-term use.

[0030] The present invention provides a tendon-rope-driven underwater dexterous hand, which is suitable for use in the work of realizing efficient and lossless adaptive grasping of underwater organisms through a manipulator. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the overall structure of the underwater dexterous hand driven by tendon ropes;

[0032] Figure 2 This is a schematic diagram of the finger structure of an underwater dexterous hand;

[0033] Figure 3 This is a schematic diagram of the distal phalanx structure of the fingers of an underwater dexterous hand;

[0034] Figure 4 This is a schematic diagram of the distal joint structure of the fingers of the underwater dexterous hand;

[0035] Figure 5 This is a schematic diagram of the waterproof motor structure of the waterproof underwater dexterous hand;

[0036] Figure 6 is a schematic diagram of the thumb structure of the improved underwater dexterous hand;

[0037] Figure 7-8 This is a schematic diagram of the driving mode of the underwater dexterous hand;

[0038] Figure 9 This is a schematic diagram of the thumb drive method of the underwater dexterous hand;

[0039] Figure 10 This is a schematic diagram of the pinky finger drive method of the underwater dexterous hand;

[0040] Figure 11 This is a schematic diagram of the coordinate system of a single finger of the underwater dexterous hand;

[0041] Figure 12 This is a schematic diagram of the working space of a single finger of the underwater dexterous hand;

[0042] Figure 13 This is a schematic diagram of the definition of the angle of a single finger joint of the underwater dexterous hand;

[0043] Figure 14 This is a schematic diagram of the internal force distribution of the tendon rope of a single finger of an underwater dexterous hand.

[0044] 1 is the distal phalanx, 2 is the waterproof housing, 3 is the six-axis force sensor, 4 is the fingertip pressure block, 5 is the sealing ring, 6 is the groove wheel, 7 is the bearing, 8 is the end cover, 9 is the lower cover, 10 is the motor housing, 11 is the bearing, 12 is the housing, 13 is the grid ring, 14 is the gasket, 15 is the bearing, 16 is the reducer housing, 17 is the rigid wheel, 18 is the flexible wheel, 19 is the wave generator, 20 is the bearing, 21 is the motor shaft, 22 is the upper cover, 23 is the motor stator, 24 is the motor rotor, 25 is the distal phalanx, 26 is the distal joint , 27 is the proximal knuckle, 28 is the base joint, 29 is the sheave for adjusting the direction of the tendon rope, 30 is the sheave, 31 is the motor, 32 is the motor, 33 is the motor, 34 is the sheave for winding the tendon rope, 35 is the sheave, 36 is the sheave, 37 is the tendon rope, 38 is the tendon rope, 39 is the tendon rope, 40 is the tendon rope, 41 is the motor, 42 is the motor, 43 is the sheave, 44 is the sheave, 45 is the tendon rope, 46 is the tendon rope, 47 is the tendon rope, 48 is the motor, 49 is the motor, 50 is the tendon rope, 51 is the tendon rope, and 52 is the sheave. DETAILED DESCRIPTION

[0045] In order to make the advantages and benefits of the technical solution provided by the present invention more clearly reflected, the technical solution provided by the present invention is now further described in detail with reference to the accompanying drawings, specifically:

[0046] Embodiment 1: This embodiment provides a tendon-driven underwater dexterous hand, comprising a palm, thumb, index finger, middle finger, ring finger, and little finger, characterized in that:

[0047] The index finger, middle finger, ring finger and little finger include distal phalanx, middle phalanx and proximal phalanx, which imitate the human knuckles;

[0048] The thumb includes a proximal knuckle and a distal knuckle, imitating human knuckles;

[0049] The palm imitates the shape of a human palm and is respectively connected to the proximal knuckles of the thumb, index finger, middle finger, ring finger and little finger.

[0050] Specifically: The main components of the dexterous hand include:

[0051] Fingers (index, middle, and ring fingers)

[0052] Distal knuckle:

[0053] Components: distal phalanx, waterproof housing, six-axis force sensor, fingertip pressure block, sealing ring

[0054] Function: The distal phalanx is connected to the waterproof housing. The six-axis force sensor detects the grasping force. The fingertip pressure block increases the grasping area and transmits the force to the sensor. The sealing ring ensures watertightness.

[0055] Middle knuckle:

[0056] Components: middle phalanx, distal joint, middle joint

[0057] Function: The distal and medial joints consist of sheaves, bearings, and end caps that provide the tendon arrangement and allow flexion of the knuckle.

[0058] Proximal knuckle:

[0059] Components: proximal phalanx, base joint

[0060] Function: The base joint includes two degrees of freedom: bending and lateral swing, and is connected to the palm.

[0061] thumb

[0062] Structure: consists of base joints and knuckles with active and passive degrees of freedom for complex grasping tasks.

[0063] Function: Connected to the palm to provide auxiliary force for grasping objects.

[0064] little finger

[0065] Structure: Similar to fingers, including distal phalanx, middle phalanx and proximal phalanx.

[0066] Function: Connects to the palm to help grasp objects stably.

[0067] palm

[0068] Structure: Connects the thumb, fingers and little finger, and contains the drive module.

[0069] Function: Serves as the foundation of the overall structure, accommodating the motor and drive module.

[0070] Driver module

[0071] Components: composed of motor

[0072] Function: Drives the movement of each finger and joint through tendons.

[0073] The shape and connection relationship of the components

[0074] Distal phalanx: Long and narrow, located at the front end of the finger, connected to the waterproof housing and the six-axis force sensor.

[0075] Waterproof housing: covers the six-axis force sensor to ensure watertightness.

[0076] Six-axis force sensor: internal structure used to detect the force of the fingertips.

[0077] Finger tip pressure block: curved shape, increasing the gripping area.

[0078] Sealing ring: ring-shaped, used for waterproof sealing.

[0079] Sheaves, bearings, and end caps: These make up the joint structure, allowing the knuckle to bend and rotate.

[0080] Base joint: has two degrees of freedom, connected to the palm, and supports the bending and lateral swing of the knuckles.

[0081] Function and connection relationship

[0082] The distal joints, middle joints and base joints of the fingers are connected to the driving module through tendon ropes. The driving module controls the stretching and relaxation of the tendon ropes through motors to achieve the bending and extension of the fingers.

[0083] Thumb and pinky: Similar to fingers, they are connected to the actuation module via tendon cords, supporting complex grasping and stabilization operations.

[0084] In general, the dexterous hand uses a tendon-driven system to achieve the movement of each joint, and the fingers, thumb and little finger work together to complete the adaptive grasping of underwater creatures and other complex underwater operation tasks.

[0085] Implementation method 2. This implementation method further limits the underwater dexterous hand driven by a tendon rope provided in implementation method 1. The distal phalanx includes a distal phalanx, a six-axis force sensor and a fingertip pressure block. The six-axis force sensor is installed at the front end of the distal phalanx, and the fingertip pressure block is installed at the front end of the six-axis force sensor.

[0086] Implementation method three: This implementation method further limits the underwater dexterous hand driven by a tendon rope provided in implementation method one. The middle phalanx includes a middle phalanx and a distal joint, and the middle phalanx is connected to the distal phalanx through the distal joint.

[0087] Implementation method 4. This implementation method further limits the underwater dexterous hand driven by a tendon rope provided in implementation method 3. The distal joint includes a sheave, a bearing and an end cover. The sheave is arranged at the end of the middle phalanx, the bearing is installed in the sheave, and the end cover closes the distal joint.

[0088] Implementation method 5. This implementation method further limits the underwater dexterous hand driven by a tendon rope provided in implementation method 1. The proximal phalanx includes a proximal phalanx and a base joint. The proximal phalanx is connected to the middle phalanx through the middle joint. The base joint has the freedom of bending and lateral swing relative to the palm.

[0089] Implementation method 6. This implementation method further limits the underwater dexterous hand driven by tendons provided in implementation method 1, and further includes a driving module, which is connected to the thumb, index finger, middle finger, ring finger and little finger through tendons.

[0090] Embodiment 7: This embodiment provides a method for controlling a tendon-driven underwater dexterous hand. The method is based on the tendon-driven underwater dexterous hand provided in Embodiment 1 and includes the following steps:

[0091] Perform system initialization and parameter preset steps;

[0092] The step of performing kinematic modeling on the dexterous hand;

[0093] The steps of collecting force and position data of each joint of the thumb, index finger, middle finger, ring finger and little finger in real time, filtering and denoising the data, and correcting model errors;

[0094] The step of obtaining a control signal according to the force and position data and outputting the control signal.

[0095] Specifically: The technical solutions provided in this embodiment include:

[0096] Step 1: System initialization and parameter setting

[0097] Output: System initialization parameters

[0098] The system boots up, loading necessary libraries and drivers.

[0099] Set the initial parameters of the dexterous hand, including DH parameters, joint angles, tendon tension, etc.

[0100] Initialize the sensors and motors and make sure all components are connected properly.

[0101] Step 2: Kinematic Modeling

[0102] Input: System initialization parameters

[0103] Output: initial position and kinematic model of each joint

[0104] The kinematic model of the dexterous hand was established using the DH parameter method.

[0105] Calculate the initial position and posture of each finger joint.

[0106] Store the kinematic model for subsequent control and simulation.

[0107] Step 3: Sensor Data Collection and Processing

[0108] Input: initial position of each joint and kinematic model

[0109] Output: Real-time force sensor and position sensor data

[0110] Start the force sensor and position sensor to collect the force and position data of each finger joint in real time.

[0111] The collected data is filtered and denoised.

[0112] The processed data are compared with the initial kinematic model to correct the model error.

[0113] Step 4: Control Algorithm Execution

[0114] Input: Real-time force sensor and position sensor data

[0115] Output: control signal

[0116] Calculate the control signals of each joint based on real-time sensor data.

[0117] The PID control algorithm is used to adjust the motor drive to ensure that the finger moves along the predetermined trajectory.

[0118] The control signal is output to the motor drive module to adjust the tendon tension and joint angle in real time.

[0119] Step 5: Feedback Adjustment and Optimization

[0120] Input: control signal

[0121] Output: Optimized motion control parameters

[0122] Monitor sensor feedback data during finger grasping and analyze the grasping effect.

[0123] Adjust control parameters based on feedback data to optimize grasping force and joint motion trajectory.

[0124] The optimized control parameters are updated to the control algorithm to improve the success rate of subsequent grasping tasks.

[0125] Embodiment 8: This embodiment provides a computer storage medium for storing a computer program. When the computer program is read by a computer, the computer executes the method provided in embodiment 7.

[0126] Implementation method 9: This implementation method provides a computer, including a processor and a storage medium. When the processor reads the computer program stored in the storage medium, the computer executes the method provided in implementation method 7.

[0127] Embodiment 10: This embodiment provides a computer program product, which is a computer program. When the computer program is executed, the method provided in embodiment 7 is implemented.

[0128] Implementation Method 11: Combination Figure 1-14 This embodiment further describes the above technical solution in detail through specific examples, specifically:

[0129] 1. To meet the operational needs of underwater dexterous hands, this embodiment designs an underactuated dexterous hand finger. This manipulator finger structure has two active degrees of freedom and one passive degree of freedom. The dimensional parameters of the dexterous hand fingers are shown in the following table:

[0130]

[0131] The distal joint of the finger has a force sensing function. The distal joint of the finger consists of a six-axis force sensor, a waterproof housing for the force sensor, and a fingertip pressure block. The front end of the distal joint of the finger is a pressure block, which relies on the arc-shaped front end design to increase the friction on the target object during grasping and transmit information such as pressure and torque during grasping to the force sensor. In order to match the output force and size of the fingertip, a small-sized six-axis force sensor is used for the distal joint of the finger. At the same time, the waterproof housing of the six-axis force sensor is integrated with the housing design of the distal phalanx of the finger, so that the housing has both the waterproof function of the six-axis force sensor and the configuration of the distal joint of the finger, and can be connected to the middle joint of the finger.

[0132] 2. Design of a waterproof underwater dexterous hand drive motor

[0133] Due to the unique underwater working environment, and to ensure the flexibility and gripping force required by the underwater dexterous hand, the fingers of the underwater dexterous hand are driven by motors. When designing the underwater dexterous hand, the drive motor must be designed to be waterproof. This embodiment uses a Gly ring seal to complete the dynamic seal design of the motor, and uses a stainless steel motor shaft and harmonic reducer to enable the motor to achieve torque output in the underwater environment and drive the movement of the underwater dexterous hand.

[0134] 3. Improved underwater dexterous hand thumb and pinky finger structure design

[0135] In order to better adapt to the diverse appearances of targets in underwater grasping tasks, this embodiment adopts an improved thumb and little finger structure of the dexterous hand.

[0136] The thumb's flexion and extension envelope is underactuated, retaining one active degree of freedom. Furthermore, the thumb's base joint is positioned at a 45-degree angle to the palm. This, combined with the thumb's flexion, allows the thumb to reach the base joint of any index finger, facilitating grasping actions for various object shapes using the thumb and index finger of the dexterous hand.

[0137] The pinky finger's design is similar to the thumb's, both employing an underactuated mechanism with one active degree of freedom. However, the pinky finger utilizes a motor connected to the base joint, enabling it to rotate perpendicular to the direction of the palm. This allows the dexterous hand to adapt to a wider range of shapes while performing tasks, increasing its flexibility.

[0138] 4. Tendon-based underwater dexterous hand driving method

[0139] The underwater dexterous hand designed in this embodiment adopts a driving method of a tendon rope driven by a motor.

[0140] The thumb and pinky fingers are connected to two motors: one motor is connected to the base joint, enabling it to rotate in a specified direction; the other motor is connected to a tendon cord, which rotates around the base joint. The tendon cord is wrapped in a figure-eight pattern around the base joint and distal joint of the thumb and pinky fingers, allowing the distal joint to follow the base joint's movement, thus achieving finger flexion.

[0141] The index finger is connected to three motors. One motor is connected to the outer end of the base joint via a tendon cord. This motor drives the tendon cord to achieve lateral swing movement. The remaining two motors are connected to the base joint and the middle joint of the index finger, respectively. One motor is connected to the base joint and controls its flexion via a tendon cord. The other motor is connected to the middle joint and controls its flexion via a tendon cord. The distal joint is driven by a tendon cord wrapped between the distal and middle joints, completing the index finger's movement.

[0142] 5. Mathematical Modeling of Underwater Dexterous Hand Based on Tendon Rope

[0143] Forward kinematic modeling of fingers of an underwater dexterous hand.

[0144] The DH parameter method is used to solve the forward kinematics of a single finger of the dexterous hand. The coordinate system of each joint of the finger is established according to the DH parameter method.

[0145] Specifically:

[0146] like Figure 1-14 As shown, the tendon-driven underwater dexterous hand includes a thumb, fingers, little finger, palm and a driving module composed of a motor.

[0147] The fingers of the underwater dexterous hand are composed of three parts: the distal phalanx, the middle phalanx, and the proximal phalanx.

[0148] The distal phalanx consists of the distal phalanx 1, waterproof housing 2, six-axis force sensor 3, fingertip pressure block 4, and sealing ring 5. The distal phalanx is connected to the waterproof housing and serves as a container for the six-axis force sensor. A sealing ring is placed above the six-axis force sensor to ensure watertightness. The fingertip pressure block is designed with a curved shape to increase the effective grasping area during operation. It also transmits the force and torque applied to the fingertip during operation to the force sensor, providing information on the force output during grasping.

[0149] The middle phalanx consists of three parts: the distal joint, the middle phalanx, and the middle joint. Both the distal joint and the middle joint are composed of a sheave 6, a bearing 7, and an end cap 8. The sheave provides the structure for the tendon; the bearing and end cap form the joint, allowing the phalanx to flex around the joint.

[0150] The proximal phalanx consists of two parts: the base joint and the proximal phalanx. The base joint has two degrees of freedom: bending and lateral swing. The sheave, bearing, and end cap provide this bending freedom. The base joint is connected to the palm above and to a tendon below, which drives the base joint's lateral swing.

[0151] The waterproof motor of the dexterous hand includes: a lower cover 9, a motor housing 10, a bearing 11, a housing 12, a grid ring 13, a gasket 14, a bearing 15, a reducer housing 16, a rigid wheel 17, a flexspline 18, a wave generator 19, a bearing 20, a motor shaft 21, an upper cover 22, a motor stator 23, and a motor rotor 24. A sealing ring is used to seal between the lower cover 9 and the housing 10; the motor stator 23 is fixed inside the housing 10; the motor shaft 21 is connected to the rotor 24, and a bearing 11 is arranged at the upper end of the housing to ensure the rotation of the motor shaft. The housing 12 is arranged above the motor housing 10 to fix the grid ring 13. The grid ring 13 is in close contact with the motor shaft 21, providing waterproof protection for the stator and rotor parts inside the motor. The gasket 14 is fixed to the upper part of the housing 12 by a shaft shoulder and connects the reducer housing 16 and the flexspline 18 via a bearing 15. The wave generator 19 is connected to the flexspline 18 via bearings and sleeves, and the wave generator 19 is connected to the upper cover 22 via bearings 20. During operation, the motor rotor 23 drives the motor shaft 21 to rotate. The motor shaft rotates around the housing 10 via bearings 11, and the connection between the housing 12 and the grid ring 13 ensures waterproofing of the stator and rotor sections of the motor. The motor shaft 21 passes through the gasket 14 and rotates around the reducer housing 16 via bearings 15. The reducer housing 16 secures the reducer's rigid pulley 17. The gasket 14 is connected to the flexspline 18 via bearings 15, allowing the motor shaft to pass through the flexspline 18 and drive its rotation. The flexspline 18 and wave generator 19 are connected via sleeves, allowing rotation of both the flexspline and the wave generator. The wave generator is connected to the upper cover 22 via bearings 20, and the motor shaft 21 passes through the upper cover 22, allowing the motor's torque to be output through the motor shaft.

[0152] The thumb and pinky finger feature an improved design. The thumb consists of a distal phalanx 25, a distal joint 26, a proximal phalanx 27, and a base joint 28. The distal phalanx is similar in structure to the index finger, differing in that the fingertip pressure block is rounded to better accommodate the multi-angle contact required by the thumb during grasping tasks. The base joint structure accommodates both thumb flexion and sideways movement. The flexion mechanism is similar to that of other knuckles, consisting of a sheave, bearing, and end caps. One side of the sideways movement is connected to the palm, housing a bearing to facilitate thumb rotation around the palm. The other side is connected to a tendon tether, which controls the thumb's sideways movement. The base joint structure of the pinky and thumb differs. Sideways movement is achieved by directly connecting the base joint to a motor, while flexion is controlled by connecting the sheave of the base joint to the motor via a tendon tether.

[0153] The finger's drive system includes sheaves 29 and 30, which adjust the tendon cord's direction; motors 31, 32, and 33, which drive the tendon cord; and sheaves 34, 35, and 36, around which the tendon cord is wound. Motor 31 is connected to sheave 34 and to tendon cord 37, which passes through the base joint of the finger and connects to the middle joint. Tendon cord 37 has two parts: one runs from above the finger, over the base joint, and directly connects to sheave 34; the other passes from the bottom of sheave 29 and the top of sheave 30, and connects to sheave 34. When motor 31 rotates, the length of the tendon cord wrapped around the middle joint changes, causing the sheave at the middle joint to rotate. Tendon cord 38 has two parts, fixed to the distal and middle joints of the finger, respectively. When the middle joint rotates, the length of cord 38 wrapped around both joints changes, causing the distal joint to follow the rotation of the middle joint. Motor 32 is connected to sheave 35, and tendon cord 39 connects sheave 35 to the curved portion of the base joint of the finger. A portion of the tendon cord 39 passes over the base joint and connects directly to sheave 35. The other portion passes through the bottom of sheave 29 and the top of sheave 30, where it connects to sheave 35. When motor 32 rotates, the length of the tendon cord wrapped around the base joint of the finger changes, causing the proximal phalanx of the finger to rotate around the base joint. Motor 33 is connected to sheave 36; tendon cord 40 connects sheave 36 to the side-swing portion of the base joint of the finger. The movement of motor 33 drives tendon cord 40 and the side-swing portion of the base joint of the finger, completing the side-swing motion of the finger.

[0154] The thumb drive system includes motors 41 and 42; sheaves 43 and 44; and tendons 45, 46, and 47. Motor 41 is connected to sheave 43; tendon 46 connects the sheave at the base of the thumb's curved joint to sheave 43. When motor 41 moves, the length of tendon 46 wrapped around the base of the thumb changes, causing the curved joint to rotate. Tendon 45 connects the curved part of the base of the thumb and the distal joint. When the base of the thumb bends and rotates, the length of tendon 45 wrapped around both joints changes, driving the distal joint to follow. Motor 42 is connected to sheave 44; tendon 47 connects sheave 44 to the side swing portion of the base joint. When motor 42 moves, the length of the connected tendons changes, driving the base of the thumb to rotate, completing the side swing motion of the thumb.

[0155] The drive system for the little finger consists of motors 48 and 49; tendons 50 and 51; and a sheave 52. The lateral swing portion of the little finger's base joint is directly connected to motor 48. The rotation of motor 48 drives the base joint of the little finger to rotate, completing the lateral swing motion of the little finger. Motor 49 is connected to sheave 52. Tendon 50 connects the curved portion of the little finger's base joint to sheave 52, and tendon 51 connects the base joint and distal joint of the little finger. When motor 49 rotates, the length of tendon 50 wrapped around the base joint changes, causing the base joint to rotate. When the base joint rotates, the length of tendon 51 wrapped around the base joint and distal joint changes, causing the distal joint to follow the movement, completing flexion and extension of the little finger.

[0156] The coordinate system of each finger of the dexterous hand is established. Among them, O0 is the base coordinate system, O1 is the coordinate system of the finger lateral swing joint, O2-O4 are the coordinate systems of the base joint, middle joint, and distal joint of the finger, and O5 is the coordinate system of the fingertip. The above coordinate system rules combined with the joint angles and link parameters of the finger can be obtained as follows:

[0157]

[0158] The general form of the link transformation matrix is:

[0159]

[0160] Among them, s is the sine function sin, and c is the cosine function cos.

[0161] According to the above DH parameter table, the transformation matrix of each adjacent link starting from the base joint can be obtained

[0162]

[0163] Based on the above description, the transformation relationship from the finger base coordinate system to the fingertip coordinate system can be obtained:

[0164] 0 T5 = 0 T1 1 T2 2 T3 3 T4 4 T5

[0165] Below is the algebraic format representation:

[0166]

[0167] Among them:

[0168] r 11 =c4(c1c2c3-c1s2s3)-s4(c1c2s3+c1c3s2)

[0169] r 12 =-c4(c1c2s3+c1c3s2)-s4(c1c2c3-c1s2s3)

[0170] r 13 = s1

[0171] r 21 =c4(c2c3s1-s1s2s3)-s4(c2s1s2+c3s1s2)

[0172] r 22 =-c4(c2s1s3+c3s1s2)-s4(c2c3s1-s1s2s3)

[0173] r 23 = -c1

[0174] r 31 =c4(c2s3+c3s2)+s4(c2c3-s2s3)

[0175] r 32 =c4(c2c3-s2s3)-s4(c2s3+c3s2)

[0176] r 33 =0

[0177] p x =a1c1+a3(c1c2c3-c1s2s3)+a4(c4(c1c2c3-c1s2s3)-s4(c1c2s3+c1c3s2)+a2c1c2

[0178] p y =a4[c4(c2c3s1-s1s2s3)-s4(c2s1s3+c3s1s2)]+a1s1+r3(c2c3s1-s1s2s3)+a2c2s1

[0179] p z =a2s2+a4[c4(c2s3+c3s2)+s4(c2c3-s2s3)+a3(c2s3+c3s2)] Thus, substituting the length of each phalanx, we can obtain the relationship between the position of the fingertip in the base coordinate system and the joint angle:

[0180]

[0181] like Figure 7 As shown, based on Figure 6 The relationship between the position of the fingertip in the base coordinate system and the joint angle can be obtained by establishing the coordinate system as shown in the figure.

[0182] based on Figure 6 The kinematic modeling of a single finger and the dynamic modeling of a single finger are as follows:

[0183]

[0184] in:

[0185] q represents the finger joint angle vector; M all represents the total mass matrix, C is the Coriolis force term and the centrifugal force term, G is the total gravity term, D is the water resistance term, τ m is the input torque.

[0186] Formula b explains the overall mass matrix M all The composition of M represents the mass matrix of the knuckle, M add is the additional mass matrix of the knuckle in the water environment.

[0187] Formula c explains the additional mass matrix M add ρ is the density of water in the underwater environment, C m is the additional mass coefficient, V is the connecting rod volume of the knuckle, L is the connecting rod length of the knuckle, and ν& is the relative acceleration between the knuckle and the water environment.

[0188] Formula d is the total gravity term, which is the resultant of the gravity and buoyancy of the finger. G is the gravity of the knuckle, F float is the buoyancy of the knuckle in water, m is the mass of the knuckle, g is the gravity constant, ρ is the density of water in the underwater environment, and V is the volume of the connecting rod of the knuckle.

[0189] For formula e: Formula e explains the resistance term. C d is the water resistance coefficient, A p is the area of the connecting rod projection in the direction of motion, and v is the relative velocity of the knuckles.

[0190] like Figure 8As shown in the figure, the relationship between the driving space and joint space of a single finger of the dexterous hand is given. Assuming that the length of the tendon is fixed during the movement, we have:

[0191]

[0192] θ1R1=-θ2R2

[0193] in, is the angle of rotation of the driver guide wheel, θ i is the angle through which the fingers of the dexterous hand rotate, R i is the radius of each sheave. Combined with the parameters of the dexterous hand's fingers, the relationship between the drive space and the joint space is as follows:

[0194]

[0195] Inverse the above relationship matrix:

[0196]

[0197] like Figure 9 Figure 2 shows the internal force distribution of the tendon cables of a single finger of a dexterous hand. Assume the fingertip output force is F, the distance from the fingertip to the distal joint is L1, the distal joint rotation angle is θ3, and the tensions of the two tendons are F1 and F2, respectively. The mid-joint rotation angle is θ2, the tensions of the two tendons connected to the distal joint are F1 and F2, respectively, and the tensions of the two tendons connected to the base joint are F3 and F4, respectively. The base joint rotation angle is θ1, the tensions of the two tendons connected to the mid-joint are F3 and F4, respectively, and the tensions of the two tendons connected to the actuator are F5 and F6, respectively.

[0198] For distal joints:

[0199]

[0200] Where r3 is the radius of the distal joint and I3 is the moment of inertia of the distal joint.

[0201] The centering joints are:

[0202]

[0203] Among them, r2 is the radius of the middle joint, and I2 is the moment of inertia of the middle joint.

[0204] The base joints are:

[0205]

[0206] Where r1 is the radius of the base joint and I1 is the moment of inertia of the base joint.

[0207] Let x1 = θ3, x3=θ2, x5=θ1, F4-F3=u1, F6-F5=u2.

[0208] Depending on how the fingers of the dexterous hand work, there are:

[0209]

[0210] Let the length change of the tendon cord connected to the medial joint on the joint be y1, and the length change of the tendon cord connected to the distal joint on the joint be y2, then:

[0211]

[0212] This embodiment adopts the above technical solution, which has the following advantages:

[0213] 1. Design of an underwater dexterous hand for underwater operations solves the problem that conventional underwater manipulators have difficulty in adaptively and non-destructively grasping target objects with diverse appearances during underwater operations. This improves the flexibility of underwater manipulators and expands the scope of application of underwater operations.

[0214] 2. Design a waterproof motor structure for the underwater dexterous hand. For the small motor used in the dexterous hand, a dynamic seal using a Gly ring was designed to waterproof the stator and rotor of the motor while maintaining the motor size and avoiding the problem of the overall size of the dexterous hand being too large.

[0215] 3. The optimized thumb and little finger structure of the underwater dexterous hand gives the dexterous hand a larger grasping range and can better envelop the target object.

[0216] 4. Design a motor-tendon drive system for underwater dexterous hands. This system achieves underactuated motion, with the base and middle joints of the index finger active and the distal joint driven, and the base joints of the thumb and index finger active and the distal joint driven. This system can also adapt to the shape of the target object.

[0217] The above further describes the technical solution provided by the present invention in detail through several specific embodiments in order to highlight the advantages and benefits of the technical solution provided by the present invention. However, the several specific embodiments described above are not intended to limit the present invention. Any reasonable modification and improvement of the present invention, combination of embodiments and equivalent replacement based on the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for controlling an underwater dexterous hand driven by a tendon rope, including the palm, thumb, index finger, middle finger, ring finger and little finger. The index finger, middle finger, ring finger and little finger include: The distal knuckle, middle knuckle, and proximal knuckle imitate human knuckles; The thumb includes a proximal knuckle and a distal knuckle, imitating human knuckles; The palm imitates the shape of a human palm and is connected to the proximal knuckles of the thumb, index finger, middle finger, ring finger and little finger respectively; The method for controlling the underwater dexterous hand driven by the tendon rope comprises the following steps: Perform system initialization and parameter preset steps; The step of performing kinematic modeling on the dexterous hand; The steps of collecting force and position data of each joint of the thumb, index finger, middle finger, ring finger and little finger in real time, filtering and denoising the data, and correcting model errors; A step of obtaining a control signal according to the force and position data, and outputting the control signal; The kinematic modeling of a single finger and the dynamic modeling of a single finger are as follows: in: Represents the finger joint angle vector; represents the overall mass matrix, are the Coriolis force term and the centrifugal force term, is the total gravity term, is the water resistance term, is the input torque; formula The overall quality matrix is explained the composition of represents the mass matrix of the knuckle, is the additional mass matrix of the knuckle in the water environment; formula Explaining the added mass matrix the composition of is the density of water in the underwater environment, is the additional mass coefficient, is the connecting rod volume of the knuckle, is the connecting rod length of the knuckle, is the relative acceleration between the knuckle and the water environment; formula is the total gravity term, which is the resultant of the gravity and buoyancy of the finger; is the weight of the knuckle, is the buoyancy of the knuckle in water, is the mass of the knuckle, is the gravitational constant, is the density of water in the underwater environment, is the connecting rod volume of the knuckle; For the formula :formula The resistance term is explained; is the water resistance coefficient, is the area of the connecting rod projection in the direction of motion, is the relative speed of the knuckles; Assuming that the length of the tendon remains constant during the movement, we have: in, is the angle of rotation of the driver guide wheel, is the angle through which the fingers of the dexterous hand turn, is the radius of each sheave. Combined with the parameters of the fingers of the dexterous hand, the relationship between the drive space and the joint space is as follows: Inverse the above relationship matrix: The force distribution inside the tendon of a single finger of the dexterous hand is defined as follows: the fingertip output force is , the distance from the fingertip to the distal joint is , the distal joint rotation angle is The tensions of the two tendons are and ; The rotation angle of the middle joint is The tensions of the two tendons connected to the distal joint are and The tensions of the two tendons connected to the base joint are and ; The base joint rotation angle is The tensions of the two tendons connected to the middle joint are and , the tensions of the two tendons connected to the actuator are and ; For distal joints: in, is the radius of the distal joint, is the moment of inertia of the distal joint; The centering joints are: in, is the radius of the mid-joint, is the moment of inertia of the mid-joint; The base joints are: in, is the radius of the base joint, is the moment of inertia of the base joint; set up ; Depending on how the fingers of the dexterous hand work, there are: Let the length of the tendon connecting the middle joint change to , the length of the tendon cord connected to the distal joint changes at the joint , then: 。 2. The method for controlling the tendon-driven underwater dexterous hand according to claim 1, characterized in that: The distal phalanx includes a distal phalanx, a six-axis force sensor and a fingertip pressure block, wherein the six-axis force sensor is mounted on the front end of the distal phalanx, and the fingertip pressure block is mounted on the front end of the six-axis force sensor; The six-axis force sensor uses a sealing ring combined with a fingertip pressure block structure and a distal phalanx to form a waterproof and sealed force measurement space.

3. The method for controlling the tendon-driven underwater dexterous hand according to claim 1, characterized in that: The middle phalanx includes a middle phalanx and a distal joint, the middle phalanx being connected to the distal phalanx via the distal joint. The finger has two active degrees of freedom, the base joint and the middle joint, and one passive degree of freedom, the distal joint. The two active degrees of freedom, the base joint and the middle joint, of the finger are directly connected to a drive module, and the length of the tendon cord winding is changed by the rotation of the drive module motor to perform active movement. The distal joint is driven by the change in the length of the tendon cord connected to the medial joint and wrapped around the joint.

4. The method for controlling the tendon-driven underwater dexterous hand according to claim 3, characterized in that: The distal joint includes a sheave, a bearing and an end cover. The sheave is arranged at the end of the middle phalanx, the bearing is installed in the sheave, the end cover closes the distal joint, and the sheave is connected to the drive module through a tendon rope.

5. The method for controlling a tendon-driven underwater dexterous hand according to claim 1, characterized in that: The proximal phalanx includes a proximal phalanx and a base joint. The proximal phalanx is connected to the middle phalanx through a middle joint. The base joint has the freedom of bending and lateral swing relative to the palm.

6. The method for controlling a tendon-driven underwater dexterous hand according to claim 1, characterized in that: It also includes a driving module, which is connected to the thumb, index finger, middle finger, ring finger and little finger through a tendon rope. The driving module includes a waterproof motor, a shell, and a reducer. The motor shaft of the waterproof motor is connected to the tendon rope through a groove pulley.

7. A computer storage medium for storing a computer program, characterized in that When the computer program is read by a computer, the computer executes the method according to claim 1 .

8. A computer comprising a processor and a storage medium, characterized in that When the processor reads the computer program stored in the storage medium, the computer executes the method according to claim 1 .

9. A computer program product, being a computer program, characterized in that When the computer program is executed, the method according to claim 1 is implemented.

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