A method for accurate modeling of serial and parallel structures of humanoid robots

Abstract

This invention belongs to the field of robot control technology and discloses a method for accurate modeling of parallel-parallel structures in humanoid robots. The method includes obtaining first target parameters for parallel linear joints and second target parameters for series linear joints, calculating the lengths of the parallel and series linear joints, determining the Jacobian matrices of the parallel and series linear joints based on the first and second target parameters, determining the thrust of the linear actuators of the parallel and series joints based on the joint torques and the inverse of the transpose of the Jacobian matrix, and performing force-position hybrid control on the linear actuators of the parallel and series joints based on the lengths and thrusts. This invention achieves accurate modeling of the motion and mechanics of linear joints in a hybrid parallel-parallel structure, thereby enabling stable force-position hybrid control of the motors.

Description

Technical Field

[0001] This invention belongs to the field of robot control technology, specifically relating to a method for accurate modeling of the serial and parallel structure of a humanoid robot. Background Technology

[0002] Humanoid robots, as a comprehensive carrier integrating cutting-edge technologies such as artificial intelligence, high-end manufacturing, new materials, and novel actuators, are widely regarded as the next disruptive product after computers, smartphones, and new energy vehicles. However, at the control and execution level, existing research mainly focuses on solving the kinematics of series or parallel structures composed of rotary motors (such as the classic Denavit-Hartenberg method and 321 configuration design). In contrast, there is still a gap in general kinematic and mechanical modeling methods for hybrid series-parallel structures driven by linear motors (such as the combination of linear joints in the legs and rotational shoulder joints).

[0003] Specifically, the mechanical characteristics of linear joints (typically employing a frameless torque motor + planetary roller screw / ball screw structure) differ fundamentally from those of rotary joints:

[0004] (1) Complexity of kinematic modeling:

[0005] Hybrid series-parallel structures require simultaneous handling of the direct kinematic analysis of the series chains and the numerical solution of the parallel chains (such as closed-loop constraint equations). The translational characteristics of linear joints break the spherical wrist simplification assumption of traditional rotary joints. Existing methods (such as biquaternion algebra and conformal geometric algebra) can improve computational efficiency, but they lack general adaptability to linear joints, especially lacking 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 to achieve end-effector force sensing, and their mechanical models need to integrate joint torque sensing data with external impact buffering mechanisms (such as series elastic actuators). Force-position hybrid control needs to solve the problem of rigid impact from linear actuators and dynamic coupling between series and parallel structures. Traditional torque control algorithms (relying on current measurement) are not robust enough to nonlinear friction and inertial disturbances.

[0008] (3) Real-time performance 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, and existing control architectures struggle to meet millisecond-level response requirements. Sensor fusion errors (such as calibration deviations between joint encoders and torque sensors) amplify the model uncertainties of hybrid structures, affecting gait balance and operational accuracy.

[0010] Therefore, how to accurately model the motion and mechanics of linear joints in a series-parallel hybrid structure, 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 this invention is to provide a method for accurate modeling of the series-parallel structure of a humanoid robot, which enables accurate modeling of the motion and mechanical models of linear joints in a series-parallel hybrid structure, thereby enabling stable force-position hybrid control of the motor.

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

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

[0014] Obtain the first target parameter of the parallel linear joint, determine the vector of the hinge point of the parallel joint linear actuator end and the universal joint relative to the origin of the lower leg reference system based on the first target parameter, obtain 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 lower leg reference system, and obtain the length of the parallel joint linear actuator based on the initial length of the parallel joint linear actuator and the relative position vector.

[0015] Obtain the second target parameter of the tandem linear joint, determine the angle between the tandem linear joint and the transmission link based on the second target parameter, determine the driving angle corresponding to the side of the tandem linear joint actuator under the triangular structure where the tandem linear joint actuator is located, based on the driving angle; obtain the length of the tandem linear joint 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 thrust 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. Force-position hybrid control is performed on the parallel joint linear actuator and the series joint linear actuator according to the length and the thrust, respectively.

[0017] Several alternative methods are provided below, but they are not intended as additional limitations on the overall solution above. They are merely further additions or optimizations. Provided there are no technical or logical contradictions, each alternative method can be combined individually with respect to the overall solution above, or multiple alternative methods can be combined with each other.

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

[0019] Based on the pitch and roll angles, determine the rotation matrix of the gimbal reference system relative to the lower leg reference system, and the rotation matrix of the foot reference system relative to the gimbal reference system, thereby obtaining the rotation matrix of the foot reference system relative to the lower leg reference system.

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

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

[0022] Preferably, the relative position vector of the parallel joint linear actuator is obtained by combining the coordinates of the fixed point of the combined parallel joint linear actuator in the lower leg reference system, including:

[0023] Based on the coordinates of the fixed point of the parallel joint linear actuator in the lower leg reference system and the origin of the lower leg reference system, calculate the vector of the fixed point of the parallel joint linear actuator relative to the origin of the lower leg reference system;

[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 lower leg reference system from the vector of the hinge point of the universal joint at the end of the parallel joint linear actuator relative to the origin of the lower leg reference system.

[0025] Preferably, the second target parameter includes the pitch angle of the tandem linear joint, and determining the angle between the tandem linear joint and the transmission link based on the second target parameter includes:

[0026] It adopts a quadrilateral structure composed of a series linear joint and a transmission link;

[0027] Based on the pitch angle and the side length of the quadrilateral structure, determine the length of the diagonal line in the quadrilateral structure that originates from the angle between the tandem linear joint and the transmission link.

[0028] Based on the length of the diagonal, the angle between the tandem linear joint and the transmission link is determined by the angles of the two sub-angles obtained by dividing the diagonal.

[0029] By combining the angles of the two sub-angles, the angle between the tandem linear joint and the transmission link is obtained.

[0030] Preferably, determining the length of the diagonal of the quadrilateral structure, originating from the angle between the tandem linear joint and the transmission link, based on the pitch angle and the side length of the quadrilateral structure, includes:

[0031] Obtain the angle of the tandem linear joint after it has rotated according to the pitch angle, with the rotation center of the tandem linear joint as the vertex and the corresponding side as the diagonal;

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

[0033] Preferably, determining the included angle of the drive corresponding to the side where the tandem joint linear actuator is located within the triangular structure includes:

[0034] Obtain the included angle between two adjacent joint links in a tandem linear joint;

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

[0036] Preferably, determining the Jacobian matrix of the parallel linear joint and the tandem linear joint based on the first target parameter and the second target parameter respectively includes:

[0037] Calculate the functional mapping relationship between the lengths of the parallel joint linear actuator and the serial joint linear actuator with respect to the first target parameter and the second target parameter, respectively;

[0038] The partial derivative functions of the parallel joint linear actuator and the serial joint linear actuator with respect to the first target parameter and the second target parameter are determined according to the function mapping relationship.

[0039] The Jacobian matrices for parallel and tandem linear joints are obtained based on the partial derivatives.

[0040] The accurate modeling method for the series and parallel structure of humanoid robots provided by this invention has the following advantages compared with the prior art:

[0041] This invention primarily solves the kinematics and mechanics problems of linear motor-driven series-parallel structures in humanoid robots with linear joints. The method is applicable to both two-degree-of-freedom systems driven by parallel linear motors and two-degree-of-freedom systems driven by series linear motors. It can also simplify multi-link structures to achieve accurate modeling. The method obtains the parameters of the link structure, joint rotation center, and mechanical structure of the humanoid robot's linear joints, determines the connection method of the linear joints based on the link structure, classifying them as series or parallel structures, obtains the pitch angle of the series joints, and determines the displacement of the linear actuators of the series joints based on the pitch angle. The pitch and roll angles of the parallel joint are obtained. 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 frame 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 fixed point of the linear actuator 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. Based on the joint torque and the transpose of the Jacobian matrix, the thrust of the linear actuator is determined, thereby performing stable force-position hybrid control of the joint motor. Attached Figure Description

[0042] Figure 1 This is a flowchart of the precise modeling method for the series and parallel structure of a humanoid robot according to the present invention;

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

[0044] Figure 3 This is a schematic diagram illustrating the definition of the reference system in the parallel linear joint of the present invention;

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

[0046] Figure 5 This is a simplified structural diagram of the tandem linear joint of the present invention. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] It should be noted that when a component is said to be "connected" to another component, it can be directly connected to the other component or it can be connected to a component in between; when a component is said to be "fixed" to another component, it can be directly fixed to the other component or it can be connected to a component in between.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0050] This embodiment proposes a general kinematic and mechanically accurate modeling method for linear joints in series-parallel hybrid structures, as follows: Figure 1 This invention presents a method for accurate modeling of the series-parallel structure of a humanoid robot. First, the mechanical structural parameters of the linear joints of the humanoid robot are obtained, including: link connection method, link length, initial angle between links, range of motion of the links, and joint rotation center. Based on the mechanical structural parameters, the connection method of the linear joints is determined, classifying them into series linear joints or parallel linear joints, and force-position hybrid control is implemented for each.

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

[0052] (1-1) Obtain the 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 the target angles that the parallel linear joint needs to achieve.

[0053] (1-2) Determine 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 lower leg reference frame based on the first target parameter, including:

[0054] Based on the pitch and roll angles, determine the rotation matrix of the gimbal reference system relative to the lower leg reference system, and the rotation matrix of the foot reference system relative to the gimbal reference system, thereby obtaining the rotation matrix of the foot reference system relative to the lower leg reference system.

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

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

[0057] It should be noted that in this embodiment, the coordinates are first obtained, and the transformed coordinates after the coordinate system transformation are obtained according to the rotation matrix. 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 being used in the calculation.

[0058] (1-3) The relative position vector of the parallel joint linear actuator is obtained by combining the coordinates of the fixed point of the parallel joint linear actuator in the lower leg reference system, including:

[0059] Based on the coordinates of the fixed point of the parallel joint linear actuator in the lower leg reference system and the origin of the lower leg reference system, calculate the vector of the fixed point of the parallel joint linear actuator relative to the origin of the lower leg reference system;

[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 lower leg reference system from the vector of the hinge point of the universal joint at the end of the parallel joint linear actuator relative to the origin of the lower leg reference system.

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

[0062] by Figure 2 The parallel linear joint shown below is used as an example to further illustrate this:

[0063] Figure 2 The structure shown has parallel joint linear actuators. and The hinge point between the end of the parallel joint linear actuator and the (foot) universal joint is and The (lower leg) fixing point of the parallel joint linear actuator is and ,in Located in and The midpoint of the line segment is named the center fixed point. The pitch and roll of the humanoid robot's ankle joint are controlled by the extension and retraction of the parallel joint linear actuator.

[0064] Figure 3 for Figure 2 The reference frame definition for the parallel linear joint shown is given. Figure 3 (a) shows the lower leg reference frame and the gimbal reference frame. Figure 3 (b) shows the foot reference frame, in which the lower leg reference frame is shown. The origin is Foot reference system The origin is Universal joint reference system The origin is In the initial case, the lower leg reference frame... Foot reference system Universal joint reference system The coordinate axes share the same direction: the X-axis points forward, the Z-axis points upward, and the Y-axis is represented horizontally according to the right-hand rule. As the lower leg and foot move, the coordinate axes will rotate in the direction of movement.

[0065] To determine the rotation matrix of the foot reference frame relative to the lower leg reference frame, a gimbal reference frame is used for association. First, the rotation matrix of the gimbal reference frame relative to the lower leg reference frame is calculated, followed by the rotation matrix of the foot reference frame relative to the gimbal reference frame. Multiplying the two matrices yields the rotation matrix of the foot reference frame relative to the lower leg reference frame, where the pitch angle is expressed as... The roll angle is expressed as Therefore, the rotation matrix of the gimbal reference frame about the lower leg reference frame is obtained as follows:

[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 lower leg reference frame is:

[0070]

[0071]

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

[0073]

[0074] In the formula, Let be the vector of the coordinates of the hinge point between the end of the parallel joint linear actuator and the universal joint in the lower leg reference frame, relative to the origin of the lower leg reference frame. This is a vector representing the coordinates (constant) of the hinge point between the end of the parallel joint linear actuator and the universal joint in the lower leg reference frame relative to the origin of the universal joint reference frame in the lower leg reference frame. The vector representing the coordinates of the origin of the lower leg reference frame relative to the origin of the gimbal reference frame below the lower leg reference frame. It is the vector of the coordinates (constant) of the hinge point between the end of the parallel joint linear actuator and the universal joint in the foot reference frame relative to the coordinates of the origin of the universal joint reference frame in the foot reference frame.

[0075] The relative position vector of the parallel joint linear actuator in the lower leg coordinate system is:

[0076]

[0077] In the formula, This is the vector representing the coordinates (constant) of the hinge point between the end of the parallel joint linear actuator and the universal joint in the lower leg reference system relative to the coordinates (constant) of the fixed point of the parallel joint actuator in the lower leg coordinate system; that is, the relative position vector of the parallel joint linear actuator in the lower leg coordinate system. The vector is the coordinate of the fixed point of the parallel joint actuator in the lower leg coordinate system relative to the origin of the lower leg reference system.

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

[0079] (2) Kinematic modeling and solution for tandem linear joints.

[0080] (2-1) Obtain the 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 the thigh joint and the 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) Determine the angle between the tandem linear joint and the transmission link based on the second target parameter, including:

[0082] It adopts a quadrilateral structure composed of a series linear joint and a transmission link;

[0083] Based on the pitch angle and the side length of the quadrilateral structure, determine the length of the diagonal line in the quadrilateral structure that originates from the angle between the tandem linear joint and the transmission link.

[0084] Based on the length of the diagonal, the angle between the tandem linear joint and the transmission link is determined by the angles of the two sub-angles obtained by dividing the diagonal.

[0085] By combining the angles of the two sub-angles, the angle between the tandem linear joint and the transmission link is obtained.

[0086] Specifically, based on the pitch angle and the side length of the quadrilateral structure, the length of the diagonal line originating from the angle between the tandem linear joint and the transmission link in the quadrilateral structure is determined, including:

[0087] Obtain the angle of the tandem linear joint after it has rotated according to the pitch angle, with the rotation center of the tandem linear joint as the vertex and the corresponding side as the diagonal;

[0088] Based on the angle of the angle and the side length of the side connected to the rotation center of the series linear joint in the quadrilateral structure, the length of the diagonal line originating 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 tandem joint linear actuator within the triangular structure. This includes:

[0090] Obtain the included angle between two adjacent joint links in a tandem linear joint;

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

[0092] (2-4) The length of the tandem joint linear actuator is obtained based on the driving angle, including:

[0093] Under the triangular structure where the tandem joint linear actuator is located, obtain the lengths of the two connecting rods on the sides of the drive connecting rod angle corresponding to the side where the actuator is located;

[0094] Determine the parameters of the cosine theorem based on the length of the connecting rod;

[0095] The length of the actuator is determined based on the parameters of the cosine theorem.

[0096] like Figure 4 As shown, in the structures of the thigh and knee joints, the thigh joint actuator is... The fixation point of the thigh joint 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 link is The thigh joint linkage is a single unit with a fixed shape, while the transmission linkage is... and The lengths of each link are known, and the actuator is activated via the thigh joint. The extension and retraction of the link drives the transmission linkage to move, causing the thigh joint linkage to rotate around the center of rotation. The robot performs pitching motions, thereby moving its thighs; the knee joint actuator is... The knee joint fixation point is The hinge point between the end of the knee joint actuator and the transmission link is The center of rotation of the knee joint is The knee joint link is , The angle remains unchanged, and the transmission link is and via knee joint actuator The extension and retraction of the knee joint linkage drives the transmission link to move, causing the knee joint link to rotate around the center of rotation. The robot makes pitching motions, which in turn move the humanoid robot's lower legs.

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

[0098] The quadrilateral structure formed by the thigh joint and the transmission link. and connect the line segments ;Pick The initial angle is added to the pitch angle of the thigh joint to obtain the result of the tandem linear joint rotating according to the pitch angle. Angle; according to Angles and line segments Length and line segment The length of the line segment is calculated using the law of cosines. Length; based on The lengths of each side are calculated using the law of cosines. From the perspective, and based on The lengths of each side are calculated using the law of cosines. From the angle, thus obtaining The angle, that is, the angle between the tandem linear joint and the transmission link; obtain Angle, subtract Angle and From the angle, we can obtain The angle, that is, the driving angle corresponding to the side where the tandem joint linear actuator is located; at the thigh joint linear actuator... In China, according to Angles and line segments Length and line segment The length of the line segment is calculated. The length of the thigh joint actuator is the length of the actuator.

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

[0100] The quadrilateral structure formed by the knee joint and the transmission link is adopted. and connect the line segments ;Pick The initial angle, subtracted from 360 degrees The initial angle, the pitch angle of the knee joint, and After the tandem linear joint rotates according to the pitch angle, Angle; according to Angles and line segments Length and line segment The length of the line segment is calculated using the law of cosines. Length; based on The lengths of each side are calculated using the law of cosines. From the perspective, and based on The lengths of each side are calculated using the law of cosines. From the angle, thus obtaining The angle, that is, the angle between the tandem linear joint and the transmission link; connecting line segment ,according to Angles and line segments Length and line segment The length of the line segment is obtained using the law of cosines. The length, and according to The lengths of each side are obtained. Angle, according to and Angle determination Angle;

[0101] use Angle, subtract Angle and From the angle, we can obtain The angle, that is, the driving angle corresponding to the side where the tandem joint linear actuator is located; in the knee joint linear actuator... In China, according to Angles and line segments Length and line segment 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 series linear joints.

[0103] (3-1) Determine the Jacobian matrices of the parallel linear joint and the tandem linear joint based on the first objective parameter and the second objective parameter, respectively, including:

[0104] Calculate the functional mapping relationship between the lengths of the parallel joint linear actuator and the serial joint linear actuator with respect to the first target parameter and the second target parameter, respectively;

[0105] The partial derivative functions of the parallel joint linear actuator and the serial joint linear actuator with respect to the first target parameter and the second target parameter are determined according to the function mapping relationship.

[0106] The Jacobian matrices for parallel and tandem linear joints are obtained based on the partial derivatives.

[0107] (3-2) Determine the thrust of the parallel joint linear actuator and the series joint linear actuator respectively based on the torque of the joint 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 formula for calculating thrust is:

[0111]

[0112] Transpose the Jacobian matrix Then calculate its inverse matrix. Combined with joint torque The thrust of the linear actuator can then be calculated. .

[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 respectively.

[0114] As can be seen from the above, the method for solving the motion and mechanics of linear joints in a humanoid robot provided in this embodiment can, given the pitch angle and torque of the series joints, determine how the drive actuator should move to move the thigh and knee joints to a target position.

[0115] Given the pitch and roll angles and torque of a parallel joint, to determine how the actuator should move to move the ankle joint to the target position, we can first determine the coordinates of the hinge point between the end of the linear actuator and the universal joint in the corresponding reference frame, thereby obtaining the linear actuator vector and the actuator length. Then, we can combine the inverse of the Jacobian matrix transpose to obtain the actuator thrust. This method is based on geometry, is efficient and simple, and can quickly control the actuator.

[0116] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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 embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for accurate modeling of the series-parallel structure of a humanoid robot, characterized in that, The method for accurate modeling of the series-parallel structure of the humanoid robot includes: Obtain the first target parameter of the parallel linear joint, determine the vector of the hinge point of the parallel joint linear actuator end and the universal joint relative to the origin of the lower leg reference system based on the first target parameter, obtain 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 lower leg reference system, and obtain the length of the parallel joint linear actuator based on the initial length of the parallel joint linear actuator and the relative position vector. Obtain the second target parameter of the tandem linear joint, determine the angle between the tandem linear joint and the transmission link based on the second target parameter, determine the driving angle corresponding to the side of the tandem linear joint actuator under the triangular structure where the tandem linear joint actuator is located, based on the driving angle; obtain the length of the tandem linear joint 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 thrust 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. Force-position hybrid control is performed on the parallel joint linear actuator and the series joint linear actuator according to the length and the thrust, respectively.

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

3. The method for accurate modeling of the series-parallel structure of a humanoid robot according to claim 1, characterized in that, The relative position vector of the parallel joint linear actuator is obtained by combining the coordinates of the fixed point of the parallel joint linear actuator in the lower leg reference system, including: Based on the coordinates of the fixed point of the parallel joint linear actuator in the lower leg reference system and the origin of the lower leg reference system, calculate the vector of the fixed point of the parallel joint linear actuator relative to the origin of the lower leg reference system; 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 lower leg reference system from the vector of the hinge point of the universal joint at the end of the parallel joint linear actuator relative to the origin of the lower leg reference system.

4. The method for accurate modeling of the series-parallel structure of a humanoid robot according to claim 1, characterized in that, The second target parameter includes the pitch angle of the tandem linear joint. Determining the angle between the tandem linear joint and the transmission link based on the second target parameter includes: It adopts a quadrilateral structure composed of a series linear joint and a transmission link; Based on the pitch angle and the side length of the quadrilateral structure, determine the length of the diagonal line in the quadrilateral structure that originates from the angle between the tandem linear joint and the transmission link. Based on the length of the diagonal, the angle between the tandem linear joint and the transmission link is determined by the angles of the two sub-angles obtained by dividing the diagonal. By combining the angles of the two sub-angles, the angle between the tandem linear joint and the transmission link is obtained.

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

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

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

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