A control system and method for a dexterous hand

Abstract

The application discloses a control system and method of a dexterous hand, wherein the system comprises a dexterous hand body, a control module, a power module, a camera, a sensor module and an upper computer; the dexterous hand body comprises a palm base and a plurality of finger units, each of the finger units comprises a finger base, a fingertip module and a plurality of knuckles, the finger base is fixedly installed on the palm base, and each of the finger units comprises a plurality of rudders for controlling the motion of the finger unit; the fingertip module comprises a fingertip, a tendon, a fingertip base and a fingertip fixing frame, the tendon and the fingertip are made of a flexible elastic material, the fingertip is installed on the fingertip fixing frame, and the tendon is used for connecting the fingertip fixing frame and the fingertip base; the power module is used for supplying power to the whole system; the camera is arranged on the palm base and is used for collecting visual image information; the control module is connected with the camera, each sensor in the sensor module and each rudder through signal lines and is connected with the upper computer.

Description

Technical Field

[0001] This invention relates to the field of dexterity technology, and in particular to a control system and method for dexterity. Background Technology

[0002] As an important end effector for humanoid robots, dexterous hands have the advantages and characteristics of high flexibility and versatility compared to traditional robotic hands that can only perform specific tasks. They can endow robots with more precise operation capabilities and stronger environmental adaptability, and are an important way to promote humanoid robots toward general artificial intelligence.

[0003] Current research on dexterous hands mainly focuses on dexterous hands made of rigid materials and soft dexterous hands made of artificial muscles. Dexterous hands made of rigid materials have the advantages of high energy conversion efficiency and good force control, but their rigid structure poses safety hazards when manipulating fragile objects and engaging in human-computer interaction, making them difficult to apply to everyday tasks. Soft dexterous hands made of artificial muscles have the advantages of convenient energy storage, good compliance, and high safety, but their dynamic control performance is relatively poor.

[0004] Therefore, in order to balance the safety and dynamic control performance of the dexterous hand, it is necessary to improve the structure, control system, and control algorithm of the dexterous hand. Summary of the Invention

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A control system for a dexterous hand includes a dexterous hand body, a control module, a power module, a camera, a sensor module, and a host computer;

[0007] The dexterous hand body includes a palm base and multiple finger units. Each finger unit includes a finger base, a fingertip module and multiple phalanges. The finger base is fixedly installed on the palm base, and each finger unit includes multiple servo motors to control its own movement.

[0008] The fingertip module includes a fingertip, a tendon, a fingertip base, and a fingertip fixing frame. The tendon and fingertip are made of a soft, elastic material. The fingertip is mounted on the fingertip fixing frame, and the tendon is used to connect the fingertip fixing frame and the fingertip base.

[0009] The power module is used to supply power to the entire system;

[0010] The camera is mounted on the palm base and is used to collect visual image information;

[0011] The control module is connected to the camera, each sensor in the sensor module and each servo motor via signal lines, and is also connected to the host computer.

[0012] The control module is used to receive information collected by the camera and sensor modules, send the current motion status of each servo motor to the host computer, and receive control commands sent by the host computer to realize closed-loop control of the dexterous hand body.

[0013] In some embodiments, for any finger unit, each phalanx includes a phalanx support and a phalanx servo fixedly mounted on the phalanx support, and a finger base servo is also fixedly mounted on the base of the finger.

[0014] In sequence from the base of the finger to the fingertip, the base of the finger servo controls the movement of the first phalanx, the last phalanx servo controls the movement of the fingertip base, and the other phalanx servos control the movement of the next phalanx.

[0015] In some embodiments, for any finger unit, the plurality of phalanges include a first phalange, a second phalange and a third phalange, the first phalange including a first phalange servo and a first phalange support, the second phalange including a second phalange servo and a second phalange support, and the third phalange including a third phalange servo and a third phalange support.

[0016] In some embodiments, the number of finger units is five, including one thumb unit and four ordinary finger units with the same structure;

[0017] For the thumb unit, the finger base servo is used to control the flexion and extension movement of the first phalanx, the first phalanx servo is used to control the rotation movement of the second phalanx, the second phalanx servo is used to control the flexion and extension movement of the third phalanx, and the third phalanx servo is used to control the flexion and extension movement of the fingertip base.

[0018] For any ordinary finger unit, the finger base servo is used to control the flexion and extension movement of the first phalanx, the first phalanx servo is used to control the lateral movement of the second phalanx, the second phalanx servo is used to control the flexion and extension movement of the third phalanx, and the third phalanx servo is used to control the flexion and extension movement of the fingertip base.

[0019] In some embodiments, a plurality of palm base servos are also installed on the palm base, and the plurality of palm base servos correspond one-to-one with a plurality of finger units;

[0020] Each palm-based servo motor is equipped with a steel wire, and a winding wheel is fixedly installed on the output shaft of the palm-based servo motor;

[0021] One end of the steel wire is wound around the winding wheel, and the other end is fixedly connected to the side of the fingertip fixing frame facing the palm base;

[0022] The hand-based servo motor is used to control the bending of the tendon via a steel wire.

[0023] In some embodiments, the system further includes an I / O module and a remote controller. The I / O module is used to send control commands from the remote controller to the control module to realize the human-computer interaction function of the dexterous hand.

[0024] Another aspect of the present invention provides a control method for a dexterous hand, employing the aforementioned control system for a dexterous hand, and comprising the following steps:

[0025] S1. Establish a kinematic model of a dexterous hand. When modeling any finger unit, the first phalanx servo, the second phalanx servo, the third phalanx servo, and the finger base servo are used together as the four rotational joints of the finger unit.

[0026] S2. For any finger unit, the host computer sends an instruction to the control module for that finger unit to obtain the desired position of the finger unit's end.

[0027] S3. Based on the kinematic model established in step S1, calculate the spatial vector of the rotational joint corresponding to the finger unit through inverse kinematic mapping.

[0028] S4. Then, calculate the servo drive vector corresponding to the spatial vector of the rotary joint through inverse kinematic mapping.

[0029] S5. Control the working state of the corresponding servo motor according to the calculation results in step S4.

[0030] In some embodiments, step S1, the step of establishing the kinematic model of the dexterous hand, specifically includes:

[0031] Establish a coordinate system for each rotary joint, denoted as O. i -X i Y i Z i (i = 1, 2, 3, 4), the origin O in the coordinate system i Located at the geometric center of the servo, Z i The axis orientation is the direction of the output axis, X i The axis direction is the direction that the finger unit points when it is fully extended. Finally, the Y-axis is selected according to the right-hand coordinate system rules. i The orientation of the axis;

[0032] The DH parameter table for each revolute joint is derived. Based on the chain rule, the derivation formula for the homogeneous transformation matrix of the (i+1)th revolute joint relative to the ith revolute joint is shown below:

[0033]

[0034] In equation (1), R X (α iDescribe the rotational joint first around X i Axis rotation α i Angle, then through translation transformation D X (a i ) so that the joint is along X i Axis translation a i Distance, then transformed by rotation R Z (θ i+1 ) around Z i+1 Axis rotation θ i+1 Angle, finally transformed by translation D Z (d i+1 Along Z i+1 Axis translation d i+1 The distance, i.e., realizing the rotational transformation from the i-th rotational joint to the (i+1)-th rotational joint, and obtaining The general expression:

[0035]

[0036] To make the expression concise, define Based on the derived DH parameter table, the homogeneous transformation matrix of each rotational joint is derived. As shown in the following formula:

[0037]

[0038] Among them, matrix and The definitions are shown in equations (4), (5), (6), and (7):

[0039]

[0040] Furthermore, for the sake of concise description (3) The elements of the definition (3) Equation (3) can be rearranged as follows:

[0041]

[0042] The specific mathematical formulas for each element are shown below:

[0043]

[0044] In the above formula, we define Thus, Equations (8) and (9) describe the influence of the rotational joint variables on the position and posture of the finger unit end.

[0045] In some embodiments, in step S3, for any finger unit, referring to equation (8), its end-position vector is expressed as: The desired position vector is represented as x * =[p x * p y * p z * ] T Define the space vector of the rotational joint as Where θ i (i = 1, 2, 3, 4) represents the rotation angle of the i-th servo motor. The goal of the inverse kinematics mapping calculation is to obtain the desired position vector x. * The spatial vector q of the revolute joint is obtained by solving for the following derivation:

[0046] Multiply the left side of equation (8) by a homogeneous transformation matrix get:

[0047]

[0048] Given that the first row and fourth column, the second row and fourth column, and the third row and fourth column of the left and right matrices in equation (10) are equal, we can obtain:

[0049]

[0050] From the second equation in (11), we can solve for θ1:

[0051]

[0052] Squaring the first and third equations in equation (11) yields θ3:

[0053]

[0054] in, In the above formula, θ3 has two solutions, and the value is taken as the one closest to the current position;

[0055] Substituting θ1 and θ3 into equation (11), we obtain θ2:

[0056]

[0057] Let equation (8) be multiplied on the left at the same time. get:

[0058]

[0059] Given that the first row and first column of the left and right sides of equation (15) are equal to the second row and second column, we get:

[0060] θ4=Atan2(s4,c4), (16)

[0061] The mathematical descriptions of s4 and c4 are as follows:

[0062]

[0063] Where r 11 r 21 r 31 As shown in equation (9);

[0064] Combining equations (12), (13), (14), and (16), the desired position vector x is thus given. * Then, the spatial vector q of the rotational joint can be calculated through inverse kinematic mapping.

[0065] In some embodiments, in step S4, the servo drive vector is defined. Where u i (i = 1, 2, 3, 4) represents the driving voltage of the i-th servo. The goal of the inverse kinematics mapping calculation is to solve for the corresponding servo driving vector u through the spatial vector q of the rotary joint. The specific derivation process is as follows:

[0066] The positive kinematic mapping from the servo drive vector to the rotary joint space vector is a linear mapping, that is:

[0067] q = Au (19)

[0068] Where A is a diagonal matrix, A = diag[0.24 0.24 0.24] T The mathematical description of the corresponding inverse kinematic mapping is as follows:

[0069] u = A -1 q (20).

[0070] Compared with the prior art, the beneficial effects of the dexterous hand control system and method provided by the present invention are as follows: The present invention adopts a special control system and method, and combines rigid knuckles with flexible fingertips and tendons, effectively balancing control dynamic performance and safety performance; thus, the dexterous hand has better compliance and higher safety performance than the dexterous hand based on rigid materials, and has higher control precision and better dynamic control performance than the soft dexterous hand based on artificial muscles. Attached Figure Description

[0071] Figure 1 A schematic diagram of the control system for the dexterous hand provided by the present invention;

[0072] Figure 2 A schematic diagram of the dexterous hand itself;

[0073] Figure 3 This is a schematic diagram of a typical finger unit;

[0074] Figure 4 This is a schematic diagram of the thumb finger unit;

[0075] Figure 5 A schematic diagram of the hand-based servo motor and related structures;

[0076] Figure 6 This is a diagram showing the connection point between two knuckles;

[0077] Figure 7 This is a schematic diagram of establishing a coordinate system for each rotational joint of a finger unit.

[0078] Explanation of icon numbers:

[0079] 1. First knuckle; 11. First knuckle support; 12. First knuckle servo; 13. Second bevel gear; 2. Second knuckle; 21. Second knuckle support; 22. Second knuckle servo; 23. Output shaft; 24. Hex bolt; 3. Third knuckle; 31. Third knuckle support; 32. Third knuckle servo; 4. Hand base; 41. Hand base servo; 42. Steel wire; 43. Winding reel; 5. Finger base servo; 51. First bevel gear; 6. Fingertip; 7. Tendon; 8. Fingertip base; 9. Fingertip retainer; 10. Ordinary finger unit; 20. Thumb unit; 100. Control module; 200. Power module; 300. Camera; 400. Sensor module; 500. Host computer; 600. I / O module; 700. Remote control. Detailed Implementation

[0080] To make the technical means, creative features, objectives and effects of this invention easier to understand, the following detailed embodiments further illustrate how this invention is implemented.

[0081] Reference Figures 1-3As shown in one specific embodiment, the present invention provides a control system for a dexterous hand, including a dexterous hand body, a control module 100, a power module 200, a camera 300, a sensor module 400, and a host computer 500; the dexterous hand body includes a palm base 4 and multiple finger units, each finger unit including a finger base, a fingertip module, and multiple phalanges, the finger base being fixedly mounted on the palm base 4, and each finger unit including multiple servo motors to control its own movement; the fingertip module includes a fingertip 6, a tendon 7, a fingertip base 8, and a fingertip fixing frame 9, the tendon 7 and the fingertip 6 being made of a soft elastic material, and the fingertip... The fingertip support 6 is mounted on the fingertip holder 9, and the tendon 7 is used to connect the fingertip holder 9 and the fingertip base 8; the power module 200 is used to power the entire system; the camera 300 is set on the palm base 4 and is used to collect visual image information; the control module 100 is connected to the camera 300, each sensor in the sensor module 400 and each servo motor through signal lines, and is connected to the host computer 500; the control module 100 is used to receive the information collected by the camera 300 and the sensor module 400, and send the current motion status of each servo motor to the host computer 500, and at the same time receive the control commands sent by the host computer 500 to realize the closed-loop control of the dexterous hand body.

[0082] Furthermore, the control system for the dexterous hand provided by the present invention also includes an I / O module 600 and a remote controller 700. The I / O module 600 is used to send control commands from the remote controller 700 to the control module 100 to realize the human-computer interaction function of the dexterous hand.

[0083] In this embodiment, the control module 100 can be an STM32F103 microcontroller, and the sensor module can include multiple visual and tactile sensors, which are respectively set at different positions of the dexterous hand. The control module 100 can be connected to each servo and sensor via serial communication, and is physically connected to the host computer 500 via USB, using serial communication to send the current motion status of each servo to the host computer.

[0084] Furthermore, for any finger unit, each phalanx includes a phalanx support and a phalanx servo fixedly mounted on the phalanx support, and a finger base servo 5 is also fixedly mounted on the base of the finger; in the order from the base of the finger to the fingertip 6, the finger base servo 5 is used to control the movement of the first phalanx, the last phalanx servo is used to control the movement of the fingertip base 8, and the other phalanx servos are used to control the movement of the next phalanx.

[0085] Additionally, refer to Figure 3As shown, the two ends of the tendon 7 can be connected to the fingertip base 8 and fingertip fixation frame 9 on the upper and lower sides through straight grooves. The fingertip 6 can be glued to the fingertip fixation frame 9, thus realizing the coupling of rigid and flexible mechanisms. The tendon 7 and fingertip 6 are made of soft elastic material, such as silicone casting; the rigid mechanisms such as the fingertip base 8 and knuckle support can be made using 3D printing technology.

[0086] Preferably, for any finger unit, the multiple phalanges include a first phalange 1, a second phalange 2, and a third phalange 3. The first phalange 1 includes a first phalange servo 12 and a first phalange support 11. The second phalange 2 includes a second phalange servo 22 and a second phalange support 21. The third phalange 3 includes a third phalange servo 32 and a third phalange support 31.

[0087] Preferably, the number of finger units is five, including one thumb unit 20 and four ordinary finger units 10 with the same structure.

[0088] Further reference Figure 4 As shown, for the thumb unit 20, the finger base servo 5 is used to control the flexion and extension movement of the first phalanx 1, the first phalanx servo 12 is used to control the rotation movement of the second phalanx 2, the second phalanx servo 22 is used to control the flexion and extension movement of the third phalanx 3, and the third phalanx servo 32 is used to control the flexion and extension movement of the fingertip base 8.

[0089] Specifically, for the thumb unit 20, the output shafts of the finger base servo 5, the second knuckle servo 22, and the third knuckle servo 32 are all perpendicular to the direction when the thumb unit 20 is extended, and the output shaft of the first knuckle servo 12 is consistent with the direction when the thumb unit 20 is extended. Furthermore, the output shaft of the finger base servo 5 is fixedly connected to the bottom side of the first knuckle support 11, the output shaft of the second knuckle servo 22 is fixedly connected to the bottom side of the third knuckle support 31, and the output shaft of the third knuckle servo 32 is fixedly connected to the bottom side of the fingertip base 8, thereby realizing the control of flexion and extension movements; the output shaft of the first knuckle servo 12 is fixedly connected to the bottom surface of the second knuckle support 21, thereby realizing the control of rotational movements.

[0090] Reference Figure 3 As shown, for any ordinary finger unit 10, the finger base servo 5 is used to control the flexion and extension movement of the first phalanx 1, the first phalanx servo 12 is used to control the lateral movement of the second phalanx 2, the second phalanx servo 22 is used to control the flexion and extension movement of the third phalanx 3, and the third phalanx servo 32 is used to control the flexion and extension movement of the fingertip base 8.

[0091] Specifically, for any ordinary finger unit 10, the direction of the output shaft of the finger base servo 5 is consistent with the direction when the ordinary finger unit 10 is straight, and the directions of the output shafts of the first knuckle servo 12, the second knuckle servo 22, and the third knuckle servo 32 are all perpendicular to the direction when the ordinary finger unit 10 is straight; the output shaft of the finger base servo 5 is fixedly connected to a first bevel gear 51, and the bottom end of the first knuckle support 11 is fixedly connected to a second bevel gear 13, the first bevel gear 51 and the second bevel gear 13 meshing with each other and The angle between the two is 90 degrees, thereby transmitting the motion of the servo output shaft to the first phalanx 1 to control the flexion and extension of the first phalanx 1; the output shaft of the first phalanx servo 12 is fixedly connected to the middle side of the second phalanx bracket 21 to control the lateral swing of the second phalanx 2; the output shaft of the second phalanx servo 22 is fixedly connected to the bottom side of the third phalanx bracket 31 to control the flexion and extension of the third phalanx 3; the output shaft of the third phalanx servo 32 is fixedly connected to the bottom side of the fingertip base 8 to control the flexion and extension of the fingertip base 8.

[0092] It is evident that the transmission design of this dexterous hand references the structure and function of the human hand, employing two different transmission design methods for the thumb and other fingers. Because the thumb is located on the front side of the other four fingers and possesses the ability to oppose itself, it can perform opposing movements (approaching or moving away from each other) with one or more other fingers. Therefore, the thumb occupies a crucial position among all parts of the human hand.

[0093] In this embodiment, the thumb unit 20's palm-opposing ability is achieved by the coordinated work of the thumb unit 20's rotational degree of freedom and the remaining flexion and extension degrees of freedom. Multiple flexion and extension degrees of freedom work together to achieve the thumb's bending function, while the rotational degree of freedom is achieved by the second phalanx 2 rotating around the output shaft of the first phalanx servo motor 12, realizing a function similar to the joints in the human hand, expanding the range of motion of the thumb unit 20, and enabling the thumb unit 20 to complete palm-opposing and palm-resisting movements.

[0094] For the ordinary finger unit 10, in order to improve structural compactness, the finger base servo 5 and the first phalanx support 11 are connected by two bevel gears, thereby realizing the motion transmission of flexion and extension degrees of freedom within a limited space. Multiple flexion and extension degrees of freedom work together to achieve the function of finger bending; while the lateral swing degree of freedom is realized by the rotation of the second phalanx 2 around the output shaft of the first phalanx servo 12, realizing the lateral swing motion of the finger on the horizontal plane, thus making the movement of the dexterous hand fingers more flexible, and at the same time increasing the redundancy of the dexterous hand's degrees of freedom.

[0095] Based on the analysis of human hand structure and finger function, this dexterous hand was designed with two different finger transmission methods, enabling the dexterous hand to complete both palm-opposing and palm-fighting movements.

[0096] Further reference Figure 5 As shown, preferably, a plurality of palm base servos 41 are also installed on the palm base 4, and the plurality of palm base servos 41 correspond one-to-one with a plurality of finger units; each palm base servo 41 is equipped with a steel wire 42, and a winding wheel 43 is fixedly installed on the output shaft of the palm base servo 41; one end of the steel wire 42 is wound on the winding wheel 43, and the other end is fixedly connected to the side of the fingertip fixing frame 9 facing the palm base 4; the palm base servo 41 is used to control the bending of the tendon 7 through the steel wire 42.

[0097] Furthermore, the steel wire 42 can pass through a pre-set hole on the fingertip base 8 and then be fixedly connected to the fingertip fixing frame 9 to limit the range of motion of the steel wire 42. The output shaft of the hand base servo motor 41 drives the winding wheel 43 to rotate forward or backward, controlling the stretching motion of the steel wire 42. When the steel wire 42 pulls the tendon 7, it causes the tendon 7 to bend under force; when the tension of the steel wire 42 on the tendon 7 decreases, the tendon 7 returns to its original position under its own elastic force. In this way, reliable control of the fingertip bending freedom is achieved, meeting the design requirements of compliance and safety performance for this dexterous hand.

[0098] As can be seen, in this embodiment, each finger is equipped with five servo motors: a palm base servo motor 41, a finger base servo motor 5, and three knuckle servo motors. That is, each finger has five degrees of freedom, so that the rigid-flexible coupled dexterous hand exhibits kinematic characteristics and configuration similar to the human hand, achieving the purpose of dexterous movement.

[0099] Furthermore, considering the requirements of the dexterous hand for control precision and dynamic performance, this rigid-flexible coupled dexterous hand adopts a simple, integrated drive design. The servo motor can be the HTS-20L type. (Refer to...) Figure 6 As shown, when a servo motor is connected to its driving structure, taking the second knuckle servo motor 22 and the third knuckle support 31 of the thumb unit 20 as an example, the lower end of the third knuckle support 31 has a threaded hole. A hexagonal bolt 24 is used to fix the third knuckle support 31 to the output shaft 23 of the second knuckle servo motor 22, thereby transmitting the rotation of the output shaft 23 to the third knuckle support 31. In this way, the offset angle of each knuckle on the control surface can be precisely controlled, achieving simple and efficient motion transmission between different knuckle levels, thus enabling the dexterous hand's palm-on-palm capability. Except for special cases (such as the finger base servo motor 5 of the ordinary finger unit 10 being connected to the first knuckle support 11 via two bevel gears), most servos and their driving structures can achieve motion transmission in a similar manner.

[0100] Another aspect of the present invention provides a control method for a dexterous hand, employing the aforementioned control system for a dexterous hand, and comprising the following steps:

[0101] S1. Establish a kinematic model of a dexterous hand. When modeling any finger unit, the first phalanx servo 12, the second phalanx servo 22, the third phalanx servo 32, and the finger base servo 5 are used together as the four rotational joints of the finger unit.

[0102] Understandably, although each finger unit has five degrees of freedom, including the four servos mentioned above as four rotational units and a finger base servo 5 for controlling the bending of the tendon 7, the finger base servo 5 operates relatively independently. It controls the corresponding tendon 7 one-to-one via the wire 42. When the operation of other servos causes a change in the overall position of the finger unit, the finger base servo 5 only needs to maintain the bending angle of the tendon 7 in the required state. Therefore, it is only necessary to model the other four servos as rotational joints.

[0103] The specific steps for establishing a kinematic model of a dexterous hand include:

[0104] Reference Figure 7 As shown, this figure corresponds to Figure 3 The modeling of the ordinary finger unit 10 in the image can be understood to follow the same principle as that of the thumb unit 20; a coordinate system is established for each rotational joint, represented as O. i -X i Y i Z i (i = 1, 2, 3, 4), the origin O in the coordinate system i Located at the geometric center of the servo, Z i The axis orientation is the direction of the output axis, X i The axis direction is the direction that the finger unit points when it is fully extended. Finally, the Y-axis is selected according to the right-hand coordinate system rules. i The orientation of the axis;

[0105] The DH parameter table for each rotary joint is derived, as shown in Table 1:

[0106] Table 1. DH Parameters of Rotational Joints

[0107]

[0108] Based on the chain rule, the derivation formula for the homogeneous transformation matrix of the (i+1)th rotation joint relative to the ith rotation joint is as follows:

[0109]

[0110] In equation (1), R X (α i Describe the rotational joint first around X i Axis rotation α i Angle, then through translation transformation D X (ai ) so that the joint is along X i Axis translation a i Distance, then transformed by rotation R Z (θ i+1 ) around Z i+1 Axis rotation θ i+1 Angle, finally transformed by translation D Z (d i+1 Along Z i+1 Axis translation d i+1 The distance, i.e., realizing the rotational transformation from the i-th rotational joint to the (i+1)-th rotational joint, and obtaining The general expression:

[0111]

[0112] To make the expression concise, define Based on the derived DH parameter table, the homogeneous transformation matrix of each rotational joint is derived. As shown in the following formula:

[0113]

[0114] Among them, matrix and The definitions are shown in equations (4), (5), (6), and (7):

[0115]

[0116] Furthermore, for the sake of concise description (3) The elements of the definition (3) Equation (3) can be rearranged as follows:

[0117]

[0118] The specific mathematical formulas for each element are shown below:

[0119]

[0120] In the above formula, we define Thus, Equations (8) and (9) describe the influence of the rotational joint variables on the position and posture of the finger unit end.

[0121] S2. For any finger unit, the host computer 500 sends an instruction to the control module 100 for that finger unit to obtain the desired position of the finger unit's end.

[0122] S3. Based on the kinematic model established in step S1, calculate the spatial vector of the rotational joint corresponding to the finger unit through inverse kinematic mapping.

[0123] For any finger unit, referring to equation (8), its end-position vector is expressed as: The desired position vector is represented as x * =[p x * p y * p z * ] T Define the space vector of the rotational joint as Where θ i (i = 1, 2, 3, 4) represents the rotation angle of the i-th servo motor. The goal of the inverse kinematics mapping calculation is to obtain the desired position vector x. * The spatial vector q of the revolute joint is obtained by solving for the following derivation:

[0124] Multiply the left side of equation (8) by a homogeneous transformation matrix get:

[0125]

[0126] Given that the first row and fourth column, the second row and fourth column, and the third row and fourth column of the left and right matrices in equation (10) are equal, we can obtain:

[0127]

[0128] From the second equation in (11), we can solve for θ1:

[0129]

[0130] Squaring the first and third equations in equation (11) yields θ3:

[0131]

[0132] in, In the above formula, θ3 has two solutions, and the value is taken as the one closest to the current position;

[0133] Substituting θ1 and θ3 into equation (11), we obtain θ2:

[0134]

[0135] Let equation (8) be multiplied on the left at the same time. get:

[0136]

[0137] Given that the first row and first column of the left and right sides of equation (15) are equal to the second row and second column, we get:

[0138] θ4=Atan2(s4,c4), (16)

[0139] The mathematical descriptions of s4 and c4 are as follows:

[0140]

[0141] Where r 11 r 21 r 31 As shown in equation (9);

[0142] Combining equations (12), (13), (14), and (16), the desired position vector x is thus given. * Then, the spatial vector q of the rotational joint can be calculated through inverse kinematic mapping.

[0143] S4. Then, calculate the servo drive vector corresponding to the spatial vector of the rotary joint through inverse kinematic mapping.

[0144] Define servo drive vector Where u i (i = 1, 2, 3, 4) represents the driving voltage of the i-th servo. The goal of the inverse kinematics mapping calculation is to solve for the corresponding servo driving vector u through the spatial vector q of the rotary joint. The specific derivation process is as follows:

[0145] The positive kinematic mapping from the servo drive vector to the rotary joint space vector is a linear mapping, that is:

[0146] q = Au (19)

[0147] Where A is a diagonal matrix, A = diag[0.24 0.24 0.24] T The mathematical description of the corresponding inverse kinematic mapping is as follows:

[0148] u = A -1 q (20).

[0149] S5. Control the working state of the corresponding servo motor according to the calculation results in step S4.

[0150] As can be seen, according to the dexterous hand control method provided by the present invention, given the desired position of the fingertip, the spatial vector of the rotational joint is calculated by inverse kinematic mapping, and the servo drive vector is further calculated by inverse kinematic mapping, so that the precise control of the fingertip position can be achieved.

[0151] In summary, this invention employs a special control system and method, combining rigid knuckles with flexible fingertips and tendons, effectively balancing control dynamic performance and safety performance. As a result, the dexterous hand has better compliance and higher safety performance compared to dexterous hands based on rigid materials, and higher control precision and better dynamic control performance compared to soft dexterous hands based on artificial muscles.

[0152] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A control system for a dexterous hand, characterized in that, It includes a dexterous hand body, a control module (100), a power module (200), a camera (300), a sensor module (400), and a host computer (500). The dexterous hand body includes a palm base (4) and multiple finger units. Each finger unit includes a finger base, a fingertip module and multiple phalanges. The finger base is fixedly installed on the palm base (4). Each finger unit includes multiple servo motors to control its own movement. The fingertip module includes a fingertip (6), a tendon (7), a fingertip base (8), and a fingertip fixing frame (9). The tendon (7) and the fingertip (6) are made of a soft elastic material. The fingertip (6) is mounted on the fingertip fixing frame (9). The tendon (7) is used to connect the fingertip fixing frame (9) and the fingertip base (8). The power module (200) is used to supply power to the entire system; The camera (300) is mounted on the palm base (4) and is used to collect visual image information; The control module (100) is connected to each sensor in the camera (300), the sensor module (400), and each servo motor via signal lines, and is also connected to the host computer (500). The control module (100) is used to receive information collected by the camera (300) and the sensor module (400), and send the current motion status of each servo motor to the host computer (500). At the same time, it receives control commands sent by the host computer (500) to realize closed-loop control of the dexterous hand body. For any finger unit, each phalanx includes a phalanx support and a phalanx servo fixedly mounted on the phalanx support, and a finger base servo is also fixedly mounted on the base of the finger (5). In the order from the base of the finger to the fingertip (6), the base of the finger servo (5) is used to control the movement of the first phalanx, the last phalanx servo is used to control the movement of the fingertip base (8), and the other phalanx servos are used to control the movement of the next phalanx. For any finger unit, multiple phalanges include a first phalanx (1), a second phalanx (2), and a third phalanx (3). The first phalanx (1) includes a first phalanx servo (12) and a first phalanx support (11). The second phalanx (2) includes a second phalanx servo (22) and a second phalanx support (21). The third phalanx (3) includes a third phalanx servo (32) and a third phalanx support (31). The number of finger units is five, including one thumb unit (20) and four ordinary finger units (10) with the same structure. For the thumb unit (20), the finger base servo (5) is used to control the flexion and extension movement of the first phalanx (1), the first phalanx servo (12) is used to control the rotation movement of the second phalanx (2), the second phalanx servo (22) is used to control the flexion and extension movement of the third phalanx (3), and the third phalanx servo (32) is used to control the flexion and extension movement of the fingertip base (8); For any ordinary finger unit (10), the finger base servo (5) is used to control the flexion and extension movement of the first phalanx (1), the first phalanx servo (12) is used to control the lateral movement of the second phalanx (2), the second phalanx servo (22) is used to control the flexion and extension movement of the third phalanx (3), and the third phalanx servo (32) is used to control the flexion and extension movement of the fingertip base (8); For the thumb unit (20), the output shafts of the finger base servo (5), the second knuckle servo (22) and the third knuckle servo (32) are all perpendicular to the direction when the thumb unit (20) is extended, and the output shaft of the first knuckle servo (12) is consistent with the direction when the thumb unit (20) is extended. For any ordinary finger unit (10), the direction of the output shaft of the finger base servo (5) is consistent with the direction when the ordinary finger unit (10) is straight. The directions of the output shafts of the first knuckle servo (12), the second knuckle servo (22) and the third knuckle servo (32) are all perpendicular to the direction when the ordinary finger unit (10) is straight.

2. The control system for a dexterous hand according to claim 1, characterized in that, The palm base (4) is also equipped with multiple palm base servo motors (41), and the multiple palm base servo motors (41) correspond one-to-one with multiple finger units; Each palm-based servo motor (41) is equipped with a steel wire (42), and a winding wheel (43) is fixedly installed on the output shaft of the palm-based servo motor (41). One end of the steel wire (42) is wound on the winding wheel (43), and the other end is fixedly connected to the side of the fingertip fixing bracket (9) facing the palm base (4); The hand base servo (41) is used to control the bending of the tendon (7) via a steel wire (42).

3. The control system for a dexterous hand according to claim 1, characterized in that, It also includes an I / O module (600) and a remote controller (700), wherein the I / O module (600) is used to send control commands from the remote controller (700) to the control module (100) to realize the human-computer interaction function of the dexterous hand.

4. A method for controlling a dexterous hand, characterized in that, The control system of the dexterous hand according to any one of claims 1-3 includes the following steps: S1. Establish a kinematic model of a dexterous hand. When modeling any finger unit, the first phalanx servo (12), the second phalanx servo (22), the third phalanx servo (32), and the finger base servo (5) are used together as the four rotational joints of the finger unit. S2. For any finger unit, the host computer (500) sends an instruction to the control module (100) for that finger unit to obtain the desired position of the end of the finger unit. S3. Based on the kinematic model established in step S1, calculate the spatial vector of the rotational joint corresponding to the finger unit through inverse kinematic mapping. S4. Then, calculate the servo drive vector corresponding to the spatial vector of the rotary joint through inverse kinematic mapping. S5. Control the working state of the corresponding servo motor according to the calculation results in step S4.

5. The method for controlling a dexterous hand according to claim 4, characterized in that, In step S1, the steps for establishing the kinematic model of the dexterous hand specifically include: Establish a coordinate system for each rotary joint, denoted as follows: ( i =1,2,3,4), the origin of the coordinate system Located at the geometric center of the servo motor, The shaft orientation is the direction of the output shaft. The axis direction is the direction that the finger unit points when it is fully extended, and it is finally selected using the right-hand coordinate system rules. The orientation of the axis; The DH parameter table for each revolute joint is derived. Based on the chain rule, the derivation formula for the homogeneous transformation matrix of the (i+1)th revolute joint relative to the ith revolute joint is shown below: (1) In equation (1), Describe the rotational joint first around Axis rotation Angle, then through translation transformation Make the joint along Axis translation Distance, then transformed by rotation Around Axis rotation Angle, finally transformed by translation. Along Axis translation Distance, i.e., achieving distance from the first i The first rotational joint to the... i +1 rotational transformation of the revolute joints, and obtain The general expression: (2) To make the expression concise, define , Based on the derived DH parameter table, the homogeneous transformation matrix of each rotational joint is derived. As shown in the following formula: (3) Among them, matrix , , and The definitions are shown in equations (4), (5), (6), and (7): (4) (5) (6) (7) Furthermore, for the sake of concise description (3) The elements of , in definition (3), , Equation (3) can be rearranged as follows: (8) The specific mathematical formulas for each element are shown below: (9) In the above formula, we define , , , Thus, equations (8) and (9) describe the influence of the rotational joint variables on the position and posture of the finger unit end.

6. The method for controlling a dexterous hand according to claim 5, characterized in that, In step S3, for any finger unit, referring to equation (8), its end-position vector is expressed as: The desired position vector is represented as Define the space vector of the rotation joint as ,in ( i =1,2,3,4) represents the first... i The rotation angle of each servo motor, the goal of inverse kinematics mapping calculation is to obtain the desired position vector. Solve for the spatial vector of the revolute joint. The specific derivation process is as follows: Multiply the left side of equation (8) by a homogeneous transformation matrix ,get: (10) Given that the first row and fourth column, the second row and fourth column, and the third row and fourth column of the left and right matrices in equation (10) are equal, we can obtain: (11) From the second equation in equation (11), we can obtain : (12) Squaring the first and third equations in equation (11) yields : (13) in, In the above formula There are two solutions; the value chosen is the one closest to the current position. Will , Substituting into equation (11), we get : (14) Let equation (8) be multiplied on the left at the same time. ,get: (15) Given that the first row and first column of the left and right sides of equation (15) are equal to the second row and second column, we get: (16) in and The mathematical description is as follows: ， (17) ， (18) in , , As shown in equation (9); Combining equations (12), (13), (14), and (16), the desired position vector is thus given. Then, the spatial vector of the rotational joint can be calculated through inverse kinematic mapping. .

7. The method for controlling a dexterous hand according to claim 6, characterized in that, In step S4, the servo drive vector is defined. ,in ( i =1,2,3,4) represents the first... i The driving voltage of each servo motor, the goal of the inverse kinematics mapping calculation is to obtain the spatial vector of the rotational joint. Solve for the corresponding servo drive vector The specific derivation process is as follows: The positive kinematic mapping from the servo drive vector to the rotary joint space vector is a linear mapping, that is: (19) Among them is diagonal matrix The mathematical description of the corresponding inverse kinematic mapping is as follows: (20)。

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