Accurate modeling method for series-parallel connection structure of humanoid robot

Abstract

The invention belongs to the technical field of robot control, and discloses a humanoid robot series-parallel connection structure accurate modeling method, which comprises the following steps: respectively acquiring a first target parameter of a parallel connection type linear joint and a second target parameter of a series connection type linear joint, and calculating to obtain the length of the parallel connection type linear joint and the length of the series connection type linear joint; according to the first target parameter and the second target parameter, Jacobian matrixes of the parallel-connection type linear joint and the series-connection type linear joint are determined respectively, and thrust of a parallel-connection joint linear actuator and thrust of a series-connection joint linear actuator are determined respectively according to the torque of the joints and inversion of transposition of the Jacobian matrixes; and force-position hybrid control is conducted on the parallel joint linear actuator and the series joint linear actuator according to the length and the thrust. According to the invention, the motion of the linear joint of the series-parallel hybrid structure and the precise modeling of the mechanical model are realized, so that the stable force-position hybrid control is carried out on the motor.

Description

Technical Field

[0001] The present invention belongs to the technical field of robot control, and in particular relates to a method for accurately modeling a series-parallel structure of a humanoid robot. Background Art

[0002] Humanoid robots, as comprehensive vehicles integrating cutting-edge technologies such as artificial intelligence, high-end manufacturing, new materials, and novel actuators, are widely viewed as the next generation of disruptive products, following computers, smartphones, and new energy vehicles. However, existing research on control and actuation focuses on solving the kinematics of series or parallel structures composed of rotary motors (e.g., the classic Denavit-Hartenberg method and 321 configuration design). In contrast, general kinematic and mechanical modeling methods for hybrid series-parallel structures driven by linear motors (e.g., the combination of linear leg joints and rotary shoulder joints) remain lacking.

[0003] Specifically, the mechanical properties of linear joints (usually using a frameless torque motor + planetary roller screw / ball screw structure) are fundamentally different from those of rotary joints:

[0004] (1) Complexity of kinematic modeling:

[0005] Hybrid series-parallel structures require both direct kinematic analysis of the series chain and numerical solutions of the parallel chain (e.g., closed-loop constraint equations). The translational properties of linear joints violate the spherical wrist simplifications of traditional revolute joints. While existing methods (such as dual quaternion algebra and conformal geometry algebra) can improve computational efficiency, they lack universal adaptability for linear joints. In particular, there is a lack of a unified forward / inverse position solution framework for hybrid structures.

[0006] (2) Mechanical coupling and control challenges:

[0007] Linear joints require high-precision six-dimensional torque sensors for end-point force sensing. Their mechanical models must integrate joint torque sensor data with external impact buffering mechanisms (such as series elastic actuators). Hybrid force-position control must address the dynamic coupling between the rigid impact of the linear actuator and the series-parallel structure. Traditional torque control algorithms (which rely on current measurement) are insufficiently robust to nonlinear friction and inertial disturbances.

[0008] (3) Real-time and accuracy bottlenecks:

[0009] The high degrees of freedom (typically ≥28 DoF) of humanoid robots lead to complex dynamic models. The addition of linear joints further increases the computational burden of real-time motion planning, making it difficult for existing control architectures to meet millisecond-level response requirements. Sensor fusion errors (such as calibration deviations between joint encoders and torque sensors) can amplify model uncertainty in the hybrid structure, affecting gait balance and operational accuracy.

[0010] Therefore, how to accurately model the motion and mechanical models of linear joints with series-parallel hybrid structures and then perform stable force-position hybrid control of the motor is an urgent problem to be solved. Summary of the Invention

[0011] The purpose of the present invention is to provide a method for accurately modeling the serial-parallel structure of a humanoid robot, so as to achieve accurate modeling of the motion and mechanical models of the linear joints of the serial-parallel hybrid structure, and then perform stable force-position hybrid control on the motor.

[0012] To achieve the above object, the technical solution adopted by the present invention is:

[0013] A method for accurately modeling a series-parallel structure of a humanoid robot, comprising:

[0014] Obtaining a first target parameter of the parallel linear joint, determining a vector between the hinge point of the end of the parallel joint linear actuator and the universal joint relative to the origin of the calf reference system based on the first target parameter, obtaining a relative position vector of the parallel joint linear actuator based on the coordinates of the fixed point of the parallel joint linear actuator in the calf reference system, and obtaining a length of the parallel joint linear actuator based on the initial length of the parallel joint linear actuator and the relative position vector;

[0015] Obtaining a second target parameter of the series linear joint, determining an angle between the series linear joint and the transmission link based on the second target parameter, and determining a driving angle corresponding to a side of the series joint linear actuator within the triangular structure where the series joint linear actuator is located based on the angle between the series linear joint and the transmission link; and obtaining a length of the series joint linear actuator based on the driving angle;

[0016] The Jacobian matrices of the parallel linear joint and the series linear joint are determined according to the first target parameter and the second target parameter, respectively. The thrusts of the parallel joint linear actuator and the series joint linear actuator are determined according to the joint torque and the inverse of the transpose of the Jacobian matrix, respectively. The parallel joint linear actuator and the series joint linear actuator are subjected to force-position hybrid control according to the length and thrust.

[0017] Several optional methods are also provided below, but they are not intended to be additional limitations on the above-mentioned overall solution. They are merely further supplements or optimizations. Under the premise that there are no technical or logical contradictions, each optional method can be combined separately for the above-mentioned overall solution, or multiple optional methods can be combined.

[0018] Preferably, the first target parameters include the pitch angle and roll angle of the parallel linear joint, and determining the vector of the hinge point between the end of the parallel joint linear actuator and the universal joint relative to the origin of the calf reference system based on the first target parameters includes:

[0019] According to the pitch angle and the roll angle, the rotation matrix of the gimbal reference system relative to the shank reference system and the rotation matrix of the foot reference system relative to the gimbal reference system are determined, thereby obtaining the rotation matrix of the foot reference system relative to the shank reference system;

[0020] Obtain the coordinates of the hinge point between the end of the parallel joint linear actuator and the universal joint in the foot reference frame after the parallel linear joint rotates according to the pitch angle and roll angle;

[0021] Based on the rotation matrix of the foot reference system relative to the calf reference system, the coordinates of the hinge point of the end of the parallel joint linear actuator and the universal joint in the calf reference system are obtained, thereby obtaining the vector of the coordinates of the hinge point of the end of the parallel joint linear actuator and the universal joint in the calf reference system relative to the origin of the calf reference system.

[0022] Preferably, the coordinates of the fixed point of the parallel joint linear actuator in the calf reference system are combined to obtain the relative position vector of the parallel joint linear actuator, including:

[0023] According to the coordinates of the fixed point of the parallel joint linear actuator in the calf reference system and the origin of the calf reference system, the vector of the fixed point of the parallel joint linear actuator relative to the origin of the calf reference system is calculated;

[0024] The relative position vector of the parallel joint linear actuator is obtained by subtracting the vector of the fixed point of the parallel joint linear actuator relative to the origin of the calf reference system from the vector of the hinge point of the end of the parallel joint linear actuator and the universal joint relative to the origin of the calf reference system.

[0025] Preferably, the second target parameter includes a pitch angle of the series linear joint, and determining the angle between the series linear joint and the transmission connecting rod according to the second target parameter includes:

[0026] A quadrilateral structure consisting of a series linear joint and a transmission connecting rod;

[0027] Determine the length of the diagonal line in the quadrilateral structure starting from the angle between the series linear joint and the transmission link based on the pitch angle and the side length of the quadrilateral structure;

[0028] Based on the length of the diagonal line, determine the angle between the series linear joint and the transmission link, and the angles of the two sub-angles obtained by dividing the angle by the diagonal line;

[0029] The angle between the series linear joint and the transmission link is obtained by combining the angles of the two sub-angles.

[0030] Preferably, determining the length of a diagonal line starting from the angle between the series linear joint and the transmission link in the quadrilateral structure according to the pitch angle and the side length of the quadrilateral structure includes:

[0031] Obtain the angle of the angle with the rotation center of the serial linear joint as the vertex and the corresponding side as the diagonal line after the serial linear joint rotates according to the pitch angle;

[0032] Based on the angle of the angle and the length of the side of the quadrilateral structure connected to the rotation center of the series linear joint, the length of the diagonal line starting from the angle between the series linear joint and the transmission link in the quadrilateral structure is calculated.

[0033] Preferably, the determining of the driving angle corresponding to the side where the serial joint linear actuator is located in the triangular structure where the serial joint linear actuator is located includes:

[0034] Get the angle between two adjacent joint links of a serial linear joint;

[0035] Take the angle between the joint links, subtract the angle between the joint links and the transmission link and the transmission link angle itself to obtain the driving angle corresponding to the side where the series joint linear actuator is located.

[0036] Preferably, determining the Jacobian matrices of the parallel linear joint and the series linear joint according to the first target parameter and the second target parameter respectively includes:

[0037] Calculating a functional mapping relationship between the lengths of the parallel joint linear actuator and the series joint linear actuator and the first target parameter and the second target parameter respectively;

[0038] Determine partial derivative functions of the parallel joint linear actuator and the series joint linear actuator with respect to the first target parameter and the second target parameter respectively according to the function mapping relationship;

[0039] According to the partial derivative functions, the Jacobian matrices of parallel linear joints and serial linear joints are obtained respectively.

[0040] The precise modeling method for the serial-parallel structure of a humanoid robot provided by the present invention has the following beneficial effects compared with the prior art:

[0041] This invention primarily addresses the kinematic and mechanical problems of serial-parallel structures driven by linear motors in humanoid robot linear joints. The method is universally applicable to both two-degree-of-freedom systems driven by parallel linear motors and two-degree-of-freedom systems driven by serial linear motors. Multi-link structures can also be simplified and accurately modeled in this way. The connecting rod structure, joint rotation center, and mechanical structure parameters of the humanoid robot's linear joints can be obtained. Based on this connecting rod structure, the linear joint's connection mode can be determined, distinguishing it as a serial or parallel structure. The pitch angle of the serial joint can be obtained, and the displacement of the linear actuator of the serial joint can be determined based on the pitch angle. The pitch and roll angles of the parallel joint are obtained, and based on the pitch and roll angles, the coordinates of the hinge point between the end of the linear actuator and the connecting rod in the corresponding reference system and the Jacobian matrix are determined. Then, the relative position vector of the linear actuator is determined based on the coordinates of the hinge point between the linear actuator fixed point and the connecting rod and the hinge point between the end of the linear actuator and the connecting rod. Then, the length of the linear actuator is determined based on the initial length of the actuator and the relative position vector of the linear actuator. The thrust of the linear actuator is determined based on the joint torque and the transpose of the Jacobian matrix, thereby performing stable force-position hybrid control on the joint motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A flow chart of the method for accurately modeling the serial-parallel structure of a humanoid robot according to the present invention;

[0043] Figure 2 This is a schematic structural diagram of the parallel linear joint of the present invention;

[0044] Figure 3 Schematic diagram of the reference system definition in the parallel linear joint of the present invention;

[0045] Figure 4 This is a schematic structural diagram of the serial linear joint of the present invention;

[0046] Figure 5 This is a simplified structural diagram of the serial linear joint of the present invention. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0048] It should be noted that when a component is referred to as being “connected” to another component, it may be directly connected to the other component or there may be a component in the middle; when a component is referred to as being “fixed” to another component, it may be directly fixed to the other component or there may be a component in the middle.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0050] In order to provide a general kinematic and mechanical accurate modeling method for linear joints of series-parallel hybrid structure, this embodiment proposes the following Figure 1 A method for accurately modeling the serial-parallel structure of a humanoid robot is shown. The method first obtains the mechanical structural parameters of the humanoid robot's linear joints, including the connecting rod connection method, connecting rod length, initial angle between connecting rods, connecting rod range of motion, and joint rotation center. Based on the mechanical structural parameters, the linear joint connection method is determined, distinguishing between serial and parallel linear joints, and implementing force-position hybrid control for each type.

[0051] (1) Kinematic modeling and solution of parallel linear joints.

[0052] (1-1) Obtaining first target parameters of the parallel linear joint. In this embodiment, the first target parameters include the pitch angle and roll angle of the parallel linear joint, which are target angles that the parallel linear joint needs to achieve.

[0053] (1-2) Determine the vector of the joint point between the end of the parallel joint linear actuator and the universal joint relative to the origin of the calf reference system based on the first target parameter, including:

[0054] According to the pitch angle and the roll angle, the rotation matrix of the gimbal reference system relative to the shank reference system and the rotation matrix of the foot reference system relative to the gimbal reference system are determined, thereby obtaining the rotation matrix of the foot reference system relative to the shank reference system;

[0055] Obtain the coordinates of the hinge point between the end of the parallel joint linear actuator and the universal joint in the foot reference frame after the parallel linear joint rotates according to the pitch angle and roll angle;

[0056] Based on the rotation matrix of the foot reference system relative to the calf reference system, the coordinates of the hinge point of the end of the parallel joint linear actuator and the universal joint in the calf reference system are obtained, thereby obtaining the vector of the coordinates of the hinge point of the end of the parallel joint linear actuator and the universal joint in the calf reference system relative to the origin of the calf reference system.

[0057] It should be noted that in this embodiment, the coordinates are first obtained, and the transformed coordinates after the coordinate system is transformed according to the rotation matrix, and then the position vector between the two points is obtained. In other embodiments, the position vector in the original coordinate system can be calculated first, and then transformed to the target coordinate system according to the rotation matrix before participating in the calculation.

[0058] (1-3) Combined with the coordinates of the fixed point of the parallel joint linear actuator in the calf reference system, the relative position vector of the parallel joint linear actuator is obtained, including:

[0059] According to the coordinates of the fixed point of the parallel joint linear actuator in the calf reference system and the origin of the calf reference system, the vector of the fixed point of the parallel joint linear actuator relative to the origin of the calf reference system is calculated;

[0060] The relative position vector of the parallel joint linear actuator is obtained by subtracting the vector of the fixed point of the parallel joint linear actuator relative to the origin of the calf reference system from the vector of the hinge point of the end of the parallel joint linear actuator and the universal joint relative to the origin of the calf reference system.

[0061] (1-4) The length of the parallel joint linear actuator is obtained according to the initial length and relative position vector of the parallel joint linear actuator.

[0062] by Figure 2 The parallel linear joint shown in the figure is used as an example to further explain:

[0063] Figure 2 In the structure shown, there are parallel joint linear actuators connected in parallel and , the hinge point between the end of the parallel joint linear actuator and the (foot) universal joint is and , the (lower leg) fixed point of the parallel joint linear actuator is and ,in Located in and The midpoint of the dotted line segment, named the central fixed point, is used to control the pitch and roll of the humanoid robot's ankle joint through the extension and contraction of the parallel joint linear actuator.

[0064] Figure 3 for Figure 2 Definition of the reference frame for the parallel linear joint shown. Figure 3 (a) shows the shank reference frame and the universal joint reference frame. Figure 3 (b) shows the foot reference frame, where the calf reference frame , the origin is ; Foot reference system , the origin is ; Universal joint reference system , the origin is In the initial case, the calf reference frame , foot reference system , universal joint reference system The coordinate axes have the same orientation: the X-axis is forward, the Z-axis is upward, and the Y-axis is horizontal according to the right-hand rule. When the calf and foot move, the coordinate axes rotate with the direction of movement.

[0065] When determining the rotation matrix of the foot reference system relative to the calf reference system, the universal joint reference system is used for association. The rotation matrix of the universal joint reference system relative to the calf reference system is calculated first, and then the rotation matrix of the foot reference system relative to the universal joint reference system is calculated. The rotation matrix of the foot reference system relative to the calf reference system can be obtained by multiplying the two. The pitch angle is expressed as , the roll angle is expressed as , so the rotation matrix of the universal joint reference system with respect to the calf reference system is:

[0066]

[0067] The rotation matrix of the foot reference frame relative to the gimbal reference frame is:

[0068]

[0069] Therefore, the rotation matrix of the foot reference frame relative to the calf reference frame is:

[0070]

[0071]

[0072] Based on the known constants and rotation matrix, calculate the coordinates of the joint point between the end of the parallel joint linear actuator and the universal joint in the calf reference system relative to the vector of the origin of the calf reference system:

[0073]

[0074] Where, is the vector of the coordinate of the joint point between the end of the parallel joint linear actuator and the universal joint in the calf reference system relative to the origin of the calf reference system, is the vector of the coordinates of the joint point between the end of the parallel joint linear actuator and the universal joint in the calf reference system relative to the coordinates (constant) of the origin of the universal joint reference system in the calf reference system, is the coordinate vector of the origin of the calf reference system relative to the origin of the universal joint reference system under the calf reference system, is the vector of the coordinates (constant) of the joint point between the end of the parallel joint linear actuator and the universal joint in the foot reference system relative to the coordinates of the origin of the universal joint reference system in the foot reference system.

[0075] Then the relative position vector of the parallel joint linear actuator in the calf coordinate system is:

[0076]

[0077] Where, is the vector of the coordinates of the hinge point between the end of the parallel joint linear actuator and the universal joint in the calf reference system relative to the coordinates (constant) of the fixed point of the parallel joint actuator in the calf coordinate system, that is, the relative position vector of the parallel joint linear actuator in the calf coordinate system, is the vector of the coordinate of the fixed point of the parallel joint actuator in the calf coordinate system relative to the origin of the calf reference system.

[0078] Based on this, the rotation matrix is ​​first calculated and the coordinates of the actuator end and the universal joint in the calf coordinate system are determined. Then, the relative position vector of the actuator in the calf reference system is determined. Finally, the sum of the initial length and the relative position vector is taken as the length of the actuator to determine the relative displacement of the actuator.

[0079] (2) Kinematic modeling and solution of serial linear joints.

[0080] (2-1) Obtaining a second target parameter of the tandem linear joint. In this embodiment, the second target parameter is the pitch angle of the tandem linear joint, which is the target angle that the tandem linear joint needs to achieve. More specifically, the tandem linear joint in this embodiment includes a thigh joint and a knee joint, so the second target parameter includes the pitch angle of the thigh joint and the pitch angle of the knee joint.

[0081] (2-2) Determining the angle between the serial linear joint and the transmission link according to the second target parameter, including:

[0082] A quadrilateral structure consisting of a series linear joint and a transmission connecting rod;

[0083] Determine the length of the diagonal line in the quadrilateral structure starting from the angle between the series linear joint and the transmission link based on the pitch angle and the side length of the quadrilateral structure;

[0084] Based on the length of the diagonal line, determine the angle between the series linear joint and the transmission link, and the angles of the two sub-angles obtained by dividing the angle by the diagonal line;

[0085] The angle between the series linear joint and the transmission link is obtained by combining the angles of the two sub-angles.

[0086] The length of the diagonal line starting from the angle between the series linear joint and the transmission link in the quadrilateral structure is determined according to the pitch angle and the side length of the quadrilateral structure, including:

[0087] Obtain the angle of the angle with the rotation center of the serial linear joint as the vertex and the corresponding side as the diagonal line after the serial linear joint rotates according to the pitch angle;

[0088] Based on the angle of the angle and the length of the side of the quadrilateral structure connected to the rotation center of the series linear joint, the length of the diagonal line starting from the angle between the series linear joint and the transmission link in the quadrilateral structure is calculated.

[0089] (2-3) Based on the angle between the actuator and the transmission link, determine the driving angle corresponding to the side of the serial joint linear actuator in the triangular structure where the serial joint linear actuator is located. This includes:

[0090] Get the angle between two adjacent joint links of a serial linear joint;

[0091] Take the angle between the joint links, subtract the angle between the joint links and the transmission link and the transmission link angle itself to obtain the driving angle corresponding to the side where the series joint linear actuator is located.

[0092] (2-4) The length of the serial joint linear actuator is obtained according to the driving angle, including:

[0093] Obtain the connecting rod lengths on both sides of the driving connecting rod angle corresponding to the actuator side in the triangular structure where the serial joint linear actuator is located;

[0094] Determine the parameters of the law of cosines according to the length of the connecting rod;

[0095] The length of the actuator is determined according to the parameters of the law of cosines.

[0096] like Figure 4 As shown, in the thigh joint and knee joint structure, the thigh joint actuator is , the thigh joint fixed point is The hinge point between the end of the thigh joint actuator and the transmission link is , the center of rotation of the thigh joint is , the upper thigh joint head is , line segment The position is fixed and the thigh joint connecting rod is The thigh joint connecting rod is a whole and fixed in shape. The transmission connecting rod is and , the length of each link is known, through the thigh joint actuator The extension and contraction drive the transmission link to move, causing the thigh joint link to rotate around the center of rotation. Perform pitching motion, thereby driving the humanoid robot thigh to move; the knee joint actuator is The knee joint fixed point is The hinge point between the end of the knee joint actuator and the transmission link is The knee joint rotation center is , the knee joint link is , The angle remains unchanged, and the transmission connecting rod is and , through the knee actuator The extension and contraction drive the transmission link to move, causing the knee joint link to rotate around the center of rotation. Perform pitching motion, thereby driving the calf movement of the humanoid robot.

[0097] like Figure 5 As shown, the calculation process for the thigh joint is as follows:

[0098] Take the quadrilateral structure composed of the thigh joint and the transmission connecting rod , and connect the line segments ;Pick The initial angle of the series linear joint is obtained by adding the pitch angle of the thigh joint to the initial angle of the series linear joint. angle; according to Angles and line segments Length and line segments The length of the line segment is calculated using the law of cosines length; based on The length of each side is calculated using the law of cosines perspective, and based on The length of each side is calculated using the law of cosines angle, thus obtaining The angle between the serial linear joint and the transmission link is obtained. angle, minus Angle and angle, get The angle of the linear actuator of the series joint is the driving angle corresponding to the side where the linear actuator of the thigh joint is located. In, according to Angles and line segments Length and line segments The length of the line segment is calculated The length of the thigh joint actuator.

[0099] The calculation process for the knee joint is as follows:

[0100] Take the quadrilateral structure composed of the knee joint and the transmission connecting rod , and connect the line segments ;Pick The initial angle is 360 degrees minus The initial angle, knee pitch angle and , we get the serial linear joint rotated according to the pitch angle angle; according to Angles and line segments Length and line segments The length of the line segment is calculated using the law of cosines length; based on The length of each side is calculated using the law of cosines perspective, and based on The length of each side is calculated using the law of cosines angle, thus obtaining The angle between the serial linear joint and the transmission link; the connecting line segment ,according to Angles and line segments Length and line segments The length of the line segment is obtained by using the law of cosines length, and according to The length of each side, we get angle, according to and Angle determination Angle;

[0101] use angle, minus Angle and angle, get The angle of the linear actuator of the series joint is the driving angle corresponding to the side where the linear actuator of the knee joint is located. In, according to Angles and line segments Length and line segments The length of the line segment is calculated The length of the knee joint actuator.

[0102] (3) Mechanical modeling and solution for parallel linear joints and serial linear joints.

[0103] (3-1) Determining the Jacobian matrices of the parallel linear joint and the serial linear joint according to the first target parameter and the second target parameter, respectively, includes:

[0104] Calculating a functional mapping relationship between the lengths of the parallel joint linear actuator and the series joint linear actuator and the first target parameter and the second target parameter respectively;

[0105] Determine partial derivative functions of the parallel joint linear actuator and the series joint linear actuator with respect to the first target parameter and the second target parameter respectively according to the function mapping relationship;

[0106] According to the partial derivative functions, the Jacobian matrices of parallel linear joints and serial linear joints are obtained respectively.

[0107] (3-2) The thrust of the parallel joint linear actuator and the series joint linear actuator are determined based on the joint torque and the inverse of the transpose of the Jacobian matrix.

[0108] Under static equilibrium, the joint torque and thrust satisfy the principle of virtual work and have the following relationship:

[0109]

[0110] Therefore, the thrust calculation formula is:

[0111]

[0112] Transpose the Jacobian matrix Then calculate its inverse matrix , combined with the joint torque , the linear actuator thrust can be obtained .

[0113] (3-3) Force-position hybrid control is performed on the parallel joint linear actuator and the series joint linear actuator according to the length and thrust.

[0114] From the above, it can be seen that the motion and mechanics solution method for the linear joints of a humanoid robot provided in this embodiment can achieve the following: when the pitch angle and torque of the serial joints are known, how to move the driving actuator to move the thigh and knee joints to the target position?

[0115] Given the pitch and roll angles and torques of the parallel joint, how should the actuator be moved to move the ankle joint to the target position? The coordinates of the hinge point between the end of the linear actuator and the universal joint in the corresponding reference frame can be determined first, thereby obtaining the linear actuator vector to obtain the actuator length, and combining the inverse matrix of the Jacobian matrix transpose to obtain the actuator thrust. This method is based on geometric methods and is efficient and simple, and can achieve rapid control of the actuator.

[0116] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0117] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for accurately modeling the serial-parallel structure of a humanoid robot, characterized in that: The method for accurately modeling the serial-parallel structure of a humanoid robot comprises: Obtaining a first target parameter of the parallel linear joint, determining a vector between the hinge point of the end of the parallel joint linear actuator and the universal joint relative to the origin of the calf reference system based on the first target parameter, obtaining a relative position vector of the parallel joint linear actuator based on the coordinates of the fixed point of the parallel joint linear actuator in the calf reference system, and obtaining a length of the parallel joint linear actuator based on the initial length of the parallel joint linear actuator and the relative position vector; Obtaining a second target parameter of the series linear joint, determining an angle between the series linear joint and the transmission link based on the second target parameter, and determining a driving angle corresponding to a side of the series joint linear actuator within the triangular structure where the series joint linear actuator is located based on the angle between the series linear joint and the transmission link; and obtaining a length of the series joint linear actuator based on the driving angle; The Jacobian matrices of the parallel linear joint and the series linear joint are determined according to the first target parameter and the second target parameter, respectively. The thrusts of the parallel joint linear actuator and the series joint linear actuator are determined according to the joint torque and the inverse of the transpose of the Jacobian matrix, respectively. The parallel joint linear actuator and the series joint linear actuator are subjected to force-position hybrid control according to the length and thrust.

2. The method for accurately modeling the serial-parallel structure of a humanoid robot according to claim 1, characterized in that: The first target parameters include the pitch angle and roll angle of the parallel linear joint. Determining the vector of the hinge point between the end of the parallel joint linear actuator and the universal joint relative to the origin of the calf reference system based on the first target parameters includes: According to the pitch angle and the roll angle, the rotation matrix of the gimbal reference system relative to the shank reference system and the rotation matrix of the foot reference system relative to the gimbal reference system are determined, thereby obtaining the rotation matrix of the foot reference system relative to the shank reference system; Obtain the coordinates of the hinge point between the end of the parallel joint linear actuator and the universal joint in the foot reference frame after the parallel linear joint rotates according to the pitch angle and roll angle; Based on the rotation matrix of the foot reference system relative to the calf reference system, the coordinates of the hinge point of the end of the parallel joint linear actuator and the universal joint in the calf reference system are obtained, thereby obtaining the vector of the coordinates of the hinge point of the end of the parallel joint linear actuator and the universal joint in the calf reference system relative to the origin of the calf reference system.

3. The method for accurately modeling the serial-parallel structure of a humanoid robot according to claim 1, characterized in that: The method of obtaining the relative position vector of the parallel joint linear actuator by combining the coordinates of the fixed point of the parallel joint linear actuator in the calf reference system includes: According to the coordinates of the fixed point of the parallel joint linear actuator in the calf reference system and the origin of the calf reference system, the vector of the fixed point of the parallel joint linear actuator relative to the origin of the calf reference system is calculated; The relative position vector of the parallel joint linear actuator is obtained by subtracting the vector of the fixed point of the parallel joint linear actuator relative to the origin of the calf reference system from the vector of the hinge point of the end of the parallel joint linear actuator and the universal joint relative to the origin of the calf reference system.

4. The method for accurately modeling the serial-parallel structure of a humanoid robot according to claim 1, characterized in that: The second target parameter includes a pitch angle of the series linear joint, and determining the angle between the series linear joint and the transmission link according to the second target parameter includes: A quadrilateral structure consisting of a series linear joint and a transmission connecting rod; Determine the length of the diagonal line in the quadrilateral structure starting from the angle between the series linear joint and the transmission link based on the pitch angle and the side length of the quadrilateral structure; Based on the length of the diagonal line, determine the angle between the series linear joint and the transmission link, and the angles of the two sub-angles obtained by dividing the angle by the diagonal line; The angle between the series linear joint and the transmission link is obtained by combining the angles of the two sub-angles.

5. The method for accurately modeling the serial-parallel structure of a humanoid robot according to claim 4, characterized in that: Determining the length of a diagonal line starting from the angle between the series linear joint and the transmission link in the quadrilateral structure according to the pitch angle and the side length of the quadrilateral structure includes: Obtain the angle of the angle with the rotation center of the serial linear joint as the vertex and the corresponding side as the diagonal line after the serial linear joint rotates according to the pitch angle; Based on the angle of the angle and the length of the side of the quadrilateral structure connected to the rotation center of the series linear joint, the length of the diagonal line starting from the angle between the series linear joint and the transmission link in the quadrilateral structure is calculated.

6. The method for accurately modeling the serial-parallel structure of a humanoid robot according to claim 1, characterized in that: Determining the driving angle corresponding to the side where the serial joint linear actuator is located in the triangular structure where the serial joint linear actuator is located includes: Get the angle between two adjacent joint links of a serial linear joint; Take the angle between the joint links, subtract the angle between the joint links and the transmission link and the transmission link angle itself to obtain the driving angle corresponding to the side where the series joint linear actuator is located.

7. The method for accurately modeling the serial-parallel structure of a humanoid robot according to claim 1, characterized in that: The method of determining the Jacobian matrices of the parallel linear joint and the serial linear joint according to the first target parameter and the second target parameter respectively includes: Calculating a functional mapping relationship between the lengths of the parallel joint linear actuator and the series joint linear actuator and the first target parameter and the second target parameter respectively; Determine partial derivative functions of the parallel joint linear actuator and the series joint linear actuator with respect to the first target parameter and the second target parameter respectively according to the function mapping relationship; According to the partial derivative functions, the Jacobian matrices of parallel linear joints and serial linear joints are obtained respectively.

Images