End contact force control method and system for hydraulically driven mobile robotic machine

Abstract

The application discloses a hydraulic driving mobile operation robot end contact force control method and relates to the field of robot force control. The method comprises the following steps: defining a coordinate system and describing the state of a four-legged robot; based on the state of the four-legged robot, considering the kinematic contact constraint of the force and torque of the operation end of a mechanical arm, and considering the foot end contact constraint of the robot, a robot floating base dynamics model based on the contact constraint is obtained; an interactive operation task is decomposed into a motion control subtask and a force control subtask, and a planned expected output is obtained; decision variables of a control system are defined, and a linear relationship expression of the actual output of the system about the decision variables is determined; a control architecture is designed, the decision variables are solved, and the control decision variables are adjusted so that the actual output of the system tends to the expected output; and force control is performed on the robot based on the solved decision variables. The output force of the leg-foot floating base is used to realize the force / motion hybrid control of the operation end.

Description

Technical Field

[0001] This invention belongs to the field of robot end-effector force control technology, and particularly relates to a method and system for controlling the end-effector contact force of a hydraulically driven mobile robot. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Mobile work robots integrate mobile robots and multi-link robotic arms, expanding workspace while improving the ability to perform complex tasks, and have broad application prospects. Due to the high power density and strong explosive force of hydraulic systems, hydraulically driven mobile work robots are widely used in various high-load operation scenarios such as engineering construction, disaster relief, and scientific exploration, which is unmatched by electrically driven mobile work robots.

[0004] With the increasing number of human-machine-environment interaction tasks, there are higher requirements for the operational compliance of mobile robots. Currently, research on mobile interactive tasks has achieved preliminary results in electrically driven lightweight mobile robots. Hydraulic mobile robots are mostly used for tasks such as material handling and obstacle clearing that do not require interaction. Unfortunately, research on interactive operation control of hydraulic platforms is limited, which significantly restricts their application. However, hydraulic platforms need to provide precise contact forces for specific tasks to improve operational quality.

[0005] However, the inventors discovered that the adjustment range of the end-effector output force of the hydraulic mobile robot for interactive operations in the prior art is relatively limited. It neither fully utilizes the advantages of the hydraulic system for high-load operation, nor can it properly ensure that the hydraulic mobile robot maintains appropriate contact force during interactive operations, which is not conducive to improving the versatility of the hydraulic mobile robot. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this invention provides an end-effector contact force control method and system for a hydraulically driven mobile robot, and designs an interactive force control strategy for a hydraulically driven mobile robotic arm, which realizes force / motion hybrid control of the end-effector through the output force of the floating base of the legs.

[0007] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions:

[0008] The first aspect of the present invention provides a method for controlling the end contact force of a hydraulically driven mobile robot.

[0009] A method for controlling the end-effector contact force of a hydraulically driven mobile robot includes the following steps:

[0010] Define a coordinate system to describe the state of the quadruped robot;

[0011] By treating the robotic arm as a linkage structure and considering the state of the quadruped robot, we can obtain a dynamic model of the robot's floating base based on contact constraints by taking into account the kinematic contact constraints of the force and torque at the end of the robotic arm and the contact constraints of the robot's feet.

[0012] The interactive task is decomposed into a motion control subtask and a force control subtask. The motion control subtask uses a proportional-derivative control method to plan the desired acceleration, while the force control subtask obtains the planned desired output through a force control strategy based on direct force feedback.

[0013] Define the decision variables of the control system, express the actual output of the system and the decision variables as a linear relationship, and determine the linear relationship expression of the actual output of the system with respect to the decision variables based on the dynamic model of the robot floating base, the kinematic contact constraints of the force and torque at the end of the robotic arm and the foot contact constraints.

[0014] Design a control architecture for the robot's end-effector contact force. Based on the linear relationship expression of the actual system output with respect to decision variables, use a quadratic optimization method to solve for the decision variables and adjust the control decision variables to make the actual system output tend to the desired output.

[0015] Based on the solved decision variables, force control is applied to the robot.

[0016] Furthermore, a coordinate system is defined to describe the state of the quadruped robot, specifically including:

[0017] Define an inertial coordinate system {I} = {O} I ,x I ,y I ,z I Any object placed at the origin O I The unit vector is {x} I ,y I ,z I}, where z I The direction is opposite to the direction of gravity; the robot's torso coordinate system {R} = {O} R ,x R ,y R ,z R Fixedly connected to the robot's torso, vector x R Along the robot's direction of travel, vector y R To the left of the robot's direction of travel; define {E} = {O E ,x E ,y E ,z E Let z be the robot's end-effector coordinate system.E Along the axial direction of the end of the operation; in n j Each joint degree of freedom plus n, representing trunk position and posture. b One virtual degree of freedom; the generalized spatial variables of the robot system are represented as:

[0018] q = [q b T ,q j T ] T

[0019] Where: q b q represents the position and orientation of the robot's torso. j Represents robot n j Joint variables.

[0020] Furthermore, considering the kinematic contact constraints of the forces and torques at the end effector of the robotic arm, and simultaneously considering the contact constraints at the robot's feet, a dynamic model of the robot's floating base based on contact constraints is obtained, specifically including:

[0021] By applying kinematic contact constraints to the force and torque at the end effector of the robotic arm, the mathematical expression for the acceleration level of the contact constraints at the end effector is obtained; the task in the direction where no position constraints are applied to the end effector of the robotic arm is completed by position control, thus obtaining the motion task expression for the direction where no constraints are applied to the end effector of the robotic arm.

[0022] Considering that the robot's foot does not slip when it touches the ground, a foot contact constraint is added, and the mathematical expression for the acceleration level of the foot contact constraint is obtained; the Jacobian matrix of the leg is calculated based on the leg structure, and the motion task expression of the robot's swing leg is obtained based on the Jacobian matrix of the leg;

[0023] Based on the mathematical expressions for the acceleration levels of the robotic arm's end-effector contact constraints and the foot-effector contact constraints, a dynamic model of the robot's floating base is obtained.

[0024] Furthermore, the dynamic model of the robot's floating base is as follows:

[0025]

[0026] Where M represents the robot's inertia matrix; C is the robot's Coriolis force and centripetal force matrix; g is the robot's gravity vector; S τ T The matrix for selecting the drive joints; τ is the torque of the robot's drive joints; f A This represents the force and torque applied to the target object at the end of the working load. This represents the interaction force and torque between the robot's foot and the ground; S AA positive semi-definite matrix, J, is used to select the direction in which motion constraints are applied. A A matrix for converting the velocity of the robot's end effector into generalized joint velocities; It is the Jacobian matrix that maps the foot state to the generalized joint space.

[0027] Furthermore, the expression for the planned expected output is:

[0028]

[0029] Where: p R Indicates trunk movement, p J Indicates joint movement, f A Indicates contact force output, Indicates end motion, This represents the swinging leg movement; variables marked with a superscript 'd' represent the expected control variables; K P,T K D,T They are positive definite matrices, representing the proportional and differential gain matrices respectively. M = {R, J, A, L} represents trunk movement, joint movement, end-effector movement, and swing leg movement respectively. Indicates the actual measured contact force; K P,F This represents the proportional matrix for adjusting the contact force.

[0030] Furthermore, the actual linear relationship expression of the system output regarding the decision variables is as follows:

[0031] w = Au + B

[0032] Where: u represents the decision variable; ω represents the actual output of the system; A and B are represented as:

[0033]

[0034]

[0035] It is the selection matrix for applying positional constraints; The Jacobian matrix representing the legs.

[0036] Furthermore, the control architecture regarding decision variables, expected output, and actual system output is as follows:

[0037]

[0038]

[0039] u l ≤u≤u u

[0040] Hf c ≤h

[0041] The decision variable of the control system is u = [τ]. T ,f A T ,f L T ] T Where W is a positive definite matrix used to set the robot's task priority and avoid task failures caused by task conflicts; S is a positive definite matrix used to minimize the system input u; u l u u These are the upper and lower bounds of the decision variable u; The Jacobian matrix represents the motion of the robotic arm's end effector and the leg's end effector; H = [H f T H j T ] T This represents the system inequality constraints that include friction stacks and joint constraints.

[0042] Friction stack constraints are a well-known optimization method for legged robots, and will not be elaborated upon here.

[0043] A second aspect of the present invention provides an end-effector contact force control system for a hydraulically driven mobile robot.

[0044] The end-effector contact force control system of a hydraulically driven mobile robot includes:

[0045] The state description module is configured to define a coordinate system and describe the state of the quadruped robot.

[0046] The robot floating base dynamics model construction module is configured to: treat the robotic arm as a linkage structure, based on the state of the quadruped robot, consider the kinematic contact constraints of the force and torque at the end of the robotic arm, and at the same time consider the contact constraints of the robot's feet, to obtain a robot floating base dynamics model based on contact constraints;

[0047] The expected output planning module is configured to decompose the interactive task into a motion control subtask and a force control subtask. The motion control subtask uses a proportional-derivative control method to plan the expected acceleration, while the force control subtask obtains the planned expected output through a force control strategy based on direct force feedback.

[0048] The linear relationship expression establishment module is configured to: define the decision variables of the control system, express the actual output of the system and the decision variables as a linear relationship, and determine the linear relationship expression of the actual output of the system with respect to the decision variables based on the dynamic model of the robot floating base, the kinematic contact constraints of the force and torque at the end of the robotic arm and the foot contact constraints;

[0049] The decision variable solving module is configured to: design a control architecture for decision variables, desired output, and actual system output; solve for decision variables using a quadratic optimization method based on the linear relationship expression of actual system output with respect to decision variables; and adjust the control decision variables to make the actual system output tend toward the desired output.

[0050] The force control module is configured to perform force control on the robot based on the solved decision variables.

[0051] A third aspect of the present invention provides a computer-readable storage medium having a program stored thereon that, when executed by a processor, implements the steps of the end-effector contact force control method for a hydraulically driven mobile work robot as described in the first aspect of the present invention.

[0052] The fourth aspect of the present invention provides an electronic device including a memory, a processor, and a program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the end-effector contact force control method for a hydraulically driven mobile work robot as described in the first aspect of the present invention.

[0053] The above one or more technical solutions have the following beneficial effects:

[0054] (1) This invention discloses an end contact force control method and system for a hydraulically driven mobile robot. In the control strategy, multiple tasks such as torso movement, end motion, interactive force control, and leg movement, as well as multiple constraints such as joint constraints and friction cones, are transformed into a multi-objective optimization problem. The priority between each task is coordinated through a weight matrix to avoid conflicts between multiple tasks.

[0055] (2) This invention decomposes the position control and force control spaces by motion constraints, and designs control laws in their respective motion spaces for control. This solves the conflict between the base output force and the current legged robot based on dynamic optimization control framework, realizes the coordinated output of torso movement and force, can adjust the range of end output force over a wide range, give full play to the advantage of the hydraulic system that can perform heavy load operations, and can maintain appropriate contact force in interactive operations, thereby improving the versatility of hydraulic mobile operation robot.

[0056] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0057] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0058] Figure 1A schematic diagram showing the establishment of the coordinate system for the first embodiment.

[0059] Figure 2 This is a flowchart of the method in the first embodiment. Detailed Implementation

[0060] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, 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.

[0061] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0062] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0063] The overall concept proposed in this invention is as follows:

[0064] Due to the highly nonlinear dynamic characteristics of mobile hydraulic manipulators, model simplification and parameter uncertainties during control lead to model inaccuracies. Furthermore, the large weight and working distance of multi-link hydraulic manipulators result in high moment of inertia, making force control challenging. Hydraulic quadruped robots typically have three active joints in their leg structure, which is simpler and easier to control than multi-degree-of-freedom manipulators. Additionally, legged robots possess redundancy, enabling motion and force control at the end effector via a quadrupedal base. Utilizing these characteristics, force control at the end effector of a mobile manipulator can be achieved through a force-controlled base, thus avoiding the difficulties of force control in multi-degree-of-freedom hydraulic manipulators. Therefore, this invention designs an interactive force control strategy for hydraulically driven mobile manipulators, achieving hybrid force / motion control at the end effector through the output force of the floating leg base.

[0065] Example 1

[0066] This embodiment discloses a method for controlling the end contact force of a hydraulically driven mobile robot.

[0067] like Figure 1-2 As shown, the end-effector contact force control method for a hydraulically driven mobile robot includes the following steps:

[0068] Define a coordinate system to describe the state of the quadruped robot;

[0069] By treating the robotic arm as a linkage structure and considering the state of the quadruped robot, we can obtain a dynamic model of the robot's floating base based on contact constraints by taking into account the kinematic contact constraints of the force and torque at the end of the robotic arm and the contact constraints of the robot's feet.

[0070] The interactive task is decomposed into a motion control subtask and a force control subtask. The motion control subtask uses a proportional-derivative control method to plan the desired acceleration, while the force control subtask obtains the planned desired output through a force control strategy based on direct force feedback.

[0071] Define the decision variables of the control system, express the actual output of the system and the decision variables as a linear relationship, and determine the linear relationship expression of the actual output of the system with respect to the decision variables based on the dynamic model of the robot floating base, the kinematic contact constraints of the force and torque at the end of the robotic arm and the foot contact constraints.

[0072] Design a control architecture for the robot's end-effector contact force. Based on the linear relationship expression of the actual system output with respect to decision variables, use a quadratic optimization method to solve for the decision variables and adjust the control decision variables to make the actual system output tend to the desired output.

[0073] Based on the solved decision variables, force control is applied to the robot.

[0074] Specifically, the specific embodiments of the present invention include two aspects: dynamic modeling based on contact constraints and design of a multi-task contact force control method.

[0075] 1. Dynamic modeling based on contact constraints

[0076] like Figure 1 As shown, to describe the state of the quadruped robot, an inertial coordinate system {I} = {O} is defined. I ,x I ,y I ,z I Any object placed at the origin O I The unit vector is {x} I ,y I ,z I}, where z I The direction is opposite to the direction of gravity. The robot's torso coordinate system {R}={O} R ,x R ,y R ,z R Fixedly connected to the robot's torso, vector x R Along the robot's direction of travel, vector y R To the left of the robot's direction of travel. Define {E} = {O} E ,x E ,y E ,z E Let z be the robot's end-effector coordinate system. E Along the axial direction at the end of the operation. To describe the floating base platform, in n j Each joint degree of freedom plus n, representing trunk position and posture.b One virtual degree of freedom. The generalized spatial variables of the robot system can be represented as:

[0077] q = [q b T ,q j T ] T (1)

[0078] Where q b This indicates the position and orientation of the robot's torso. q j Represents robot n j Joint variables.

[0079] The h in the text A This indicates the position and orientation of the working load in contact with the target object in the inertial coordinate system, represented by... This indicates the position and posture of the quadruped robot's feet interacting with the ground. A This represents the force and torque applied to the target object at the end of the working load. This represents the interaction force and torque between the robot's foot and the ground.

[0080] By treating the airborne robotic arm as a linkage structure, we can obtain the mapping relationship between the velocity of the robotic arm's end effector and the torso's center of mass:

[0081]

[0082] r ab Let r be the position vector from the end of the operation to the center of mass of the torso. ab× Let J be the skew-symmetric matrix representing the cross product, and let I and 0 represent the identity matrix and the zero matrix, respectively. A The velocity at the end of the robot's work load can be converted into a generalized joint velocity, and only matrix J needs to be modified when changing different tools. A .

[0083] The robot's work object is assumed to be rigid and smooth, an assumption suitable for practical industrial scenarios such as grinding and welding. The application of force and torque requires corresponding positional constraints, therefore kinematic constraints need to be applied to the end effector of the moving robotic arm to describe the interaction contact model.

[0084]

[0085] Where S A A positive semi-definite matrix, used to select the direction in which motion constraints are applied; the number of motion constraint directions is n. c In each interactive task, S A The value remains unchanged. Using a kinematic model, the end-effector contact constraint is mapped to the generalized joint space:

[0086]

[0087] in Differentiating equation (4) with respect to time yields the mathematical expression for the acceleration level of the end-effector contact constraint:

[0088]

[0089] The remaining directions without positional constraints complete the task through positional control, and their constraint expression can be written as:

[0090]

[0091] in in It is the selection matrix for applying positional constraints, and it is matrix S. A Supplement, v A This indicates the velocity in the direction where no position constraint is applied at the end.

[0092] Differentiating equation (6) with respect to time yields the unconstrained motion task of the robotic arm's end effector:

[0093]

[0094] To prevent the robot's feet from slipping when they touch the ground, we added... Due to the constraints, the number of foot-to-ground contact constraints is n. k The constraint of foot contact with the ground in the generalized joint space can be represented as:

[0095]

[0096] here It is the Jacobian matrix that maps the foot state to the generalized joint space. Differentiating equation (8) with respect to time yields the mathematical expression for the acceleration level of the foot contact constraint:

[0097]

[0098] Simultaneously, the Jacobian matrix J calculated based on the leg structure... L f It can achieve the end velocity v of the swing leg. L Mapping to generalized joint space:

[0099]

[0100] Differentiating equation (10) with respect to time yields the robot's swing leg motion task:

[0101]

[0102] Based on the above derivation of the contact constraints at the end of the mobile robotic arm and its feet, the dynamic model of the robot's floating base can be expressed as:

[0103]

[0104] Where M is the robot's inertia matrix, C is the robot's Coriolis force and centripetal force matrix, g is the robot's gravity vector, and S... τ T The matrix is ​​selected to drive the joints, where τ is the torque of the robot's drive joints.

[0105] 2. Contact Force Control Method Based on Multi-Task Optimization

[0106] The block diagram of the mobile contact force control method of the present invention is as follows: Figure 2 As shown, the robot divides the contact force operation task into a motion control part and a force control part through motion constraints. The force control part uses a control method based on direct force feedback, while the motion control part uses proportional-derivative control to design the desired acceleration. Finally, multiple control tasks and multiple constraints are transformed into a multi-task quadratic optimization problem for solution.

[0107] Because robot contact operations involve multiple tasks, including trunk movements... R Joint movement p J Contact force output f A End motion and swing leg exercise Therefore, the system output is defined as...

[0108]

[0109] Furthermore, this paper defines the decision variables of the control system as follows:

[0110] u = [τ] T ,f A T ,f L T ] T (14)

[0111] (1) Motion / force hybrid control

[0112] Based on the motion constraints derived earlier, the interactive task is decomposed into a motion control subtask and a force control subtask. The motion subtask uses a proportional-derivative control method to plan the desired acceleration, while the force control subtask employs a direct force feedback-based force control strategy, incorporating data from actual force sensors to compensate for disturbances such as friction. The planned desired output ω... * It can be represented as:

[0113]

[0114] Among them, variables marked with the superscript 'd' represent expected control variables. K P,T K D,T These are positive definite matrices, representing the proportional and differential gain matrices respectively. T = {R, J, A, L} represents trunk movement, joint movement, end-effector movement, and swing leg movement respectively. K represents the actual measured contact force. P,F This represents the proportional matrix for adjusting the contact force.

[0115] (2) Multi-task optimization control

[0116] Combining the dynamic model of the floating base based on contact constraints (12) derived above, the end effector motion task (7) of the robotic arm, and the motion task of the swing leg (11), the relationship between the system output ω and the decision variable u can be expressed in the following form:

[0117] w = Au + B (16)

[0118] Where A and B do not contain the control input u, A and B can be represented as:

[0119]

[0120]

[0121] By adjusting the control input u, ω is made to tend towards ω. * Since ω and u are linearly related in equation (16), this paper uses a quadratic optimization method to solve for the decision variable u, and the control architecture adopts the following form:

[0122]

[0123] Where W is a positive definite matrix used to set the robot's task priorities and avoid task failures caused by task conflicts. S is a positive definite matrix used to minimize the system input u. l u u It controls the upper and lower bounds of the input variable u. This represents the Jacobian matrix containing the motion of the robotic arm's end effector and the leg's end effector. H = [H f T H j T ] T This represents the system inequality constraints that include friction stacks and joint constraints.

[0124] Example 2

[0125] This embodiment discloses an end-effector contact force control system for a hydraulically driven mobile robot.

[0126] The end-effector contact force control system of a hydraulically driven mobile robot includes:

[0127] The state description module is configured to define a coordinate system and describe the state of the quadruped robot.

[0128] The robot floating base dynamics model construction module is configured to: treat the robotic arm as a linkage structure, based on the state of the quadruped robot, consider the kinematic contact constraints of the force and torque at the end of the robotic arm, and at the same time consider the contact constraints of the robot's feet, to obtain a robot floating base dynamics model based on contact constraints;

[0129] The expected output planning module is configured to decompose the interactive task into a motion control subtask and a force control subtask. The motion control subtask uses a proportional-derivative control method to plan the expected acceleration, while the force control subtask obtains the planned expected output through a force control strategy based on direct force feedback.

[0130] The linear relationship expression establishment module is configured to: define the decision variables of the control system, express the actual output of the system and the decision variables as a linear relationship, and determine the linear relationship expression of the actual output of the system with respect to the decision variables based on the dynamic model of the robot floating base, the kinematic contact constraints of the force and torque at the end of the robotic arm and the foot contact constraints;

[0131] The decision variable solving module is configured to: design a control architecture for the robot's end-effector contact force; solve the decision variables using a quadratic optimization method based on the linear relationship expression of the actual system output with respect to the decision variables; and adjust the control decision variables to make the actual system output tend towards the desired output.

[0132] The force control module is configured to perform force control on the robot based on the solved decision variables.

[0133] Example 3

[0134] The purpose of this embodiment is to provide a computer-readable storage medium.

[0135] A computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the steps of the end-effector contact force control method for a hydraulically driven mobile work robot as described in Embodiment 1 of this disclosure.

[0136] Example 4

[0137] The purpose of this embodiment is to provide an electronic device.

[0138] An electronic device includes a memory, a processor, and a program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps in the end-effector contact force control method for a hydraulically driven mobile robot as described in Embodiment 1 of this disclosure.

[0139] The steps and methods involved in the apparatuses of Embodiments 2, 3, and 4 above correspond to those in Embodiment 1. For specific implementation details, please refer to the relevant description section of Embodiment 1. The term "computer-readable storage medium" should be understood as a single medium or multiple media including one or more instruction sets; it should also be understood as including any medium capable of storing, encoding, or carrying an instruction set for execution by a processor and enabling the processor to perform any of the methods in this invention.

[0140] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0141] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for controlling an end contact force of a hydraulic drive mobile work robot, characterized by, The method comprises the following steps: defining a coordinate system to describe the state of the quadruped robot; considering the kinematic contact constraints of the force and torque of the mechanical arm work end and the foot end contact constraints of the robot, obtaining a robot floating base dynamics model based on the contact constraints; decomposing the interactive work task into a motion control subtask and a force control subtask, wherein the motion control subtask adopts a proportional differential control mode to plan an expected acceleration, and the force control subtask obtains a planned expected output through a force control strategy based on direct force feedback; defining decision variables of the control system, expressing the system actual output and the decision variables as a linear relationship, determining a linear relationship expression of the system actual output with respect to the decision variables based on the robot floating base dynamics model, the kinematic contact constraints of the force and torque of the mechanical arm work end, and the foot end contact constraints; designing a control architecture with respect to the robot end contact force, adopting a quadratic optimization method to solve the decision variables based on the linear relationship expression of the system actual output with respect to the decision variables, and adjusting the control decision variables to make the system actual output tend to the expected output; controlling the robot based on the solved decision variables.

2. The hydraulic drive mobile work robot's end contact force control method according to claim 1, characterized by, defining a coordinate system to describe the state of the quadruped robot, specifically comprising: The inertial coordinate system is defined as , is the coordinate origin, and the unit vector is , where the direction is opposite to the direction of gravity; the robot trunk coordinate system is fixedly connected at the robot trunk, and the vector is along the forward direction of the robot, and the vector is along the left side of the forward direction of the robot; the definition is the robot end coordinate system, where is along the axial direction of the work end; in one joint degree of freedom plus one virtual degree of freedom representing the trunk position and posture; the robot system generalized space variable is represented as: wherein: represents the position and pose of the robot trunk, represents the robot joint variables.

3. The hydraulic drive mobile work robot's end contact force control method according to claim 1, characterized by, considering the kinematic contact constraints of the force and torque of the mechanical arm work end and the foot end contact constraints of the robot, obtaining a robot floating base dynamics model based on the contact constraints, specifically comprising: applying kinematic contact constraints to the force and torque of the mechanical arm work end to obtain an acceleration level mathematical expression of the mechanical arm work end contact constraints; completing the task through position control in a direction of the mechanical arm work end to which no position constraint is applied, to obtain a motion task expression of the direction of the mechanical arm work end to which no constraint is applied; considering that the robot foot end does not slip when touching the ground, adding a foot ground contact constraint to obtain an acceleration level mathematical expression of the foot end contact constraint; calculating a leg Jacobian matrix based on the leg structure, and obtaining a motion task expression of the robot swing leg based on the leg Jacobian matrix; obtaining a robot floating base dynamics model based on the acceleration level mathematical expression of the mechanical arm work end contact constraint and the acceleration level mathematical expression of the foot end contact constraint.

4. The hydraulic drive mobile work robot's end contact force control method according to claim 2, characterized by, The robot floating base dynamics model is: wherein, represents the robot inertia matrix; is the robot Coriolis and centripetal force matrix; is the robot gravity vector; is the drive joint selection matrix; is the robot drive joint torque; represents the force and torque exerted by the work load end-effector on the target object, represents the interaction force and torque between the robot foot and the ground; , is a positive semi-definite matrix used to select the direction of motion constraint application, is the matrix that transforms the velocity of the robot work load end-effector to the generalized joint velocity; is the Jacobian matrix that maps the foot state to the generalized joint space.

5. The hydraulic drive mobile work robot's end contact force control method according to claim 4, characterized by, The expression of the planned expected output is: wherein: represents trunk motion, represents joint motion, represents end-effector motion, represents swing leg motion; variables annotated with a superscript represent desired control variables; is a positive definite matrix representing proportional, derivative gain matrices, represent trunk motion, joint motion, end-effector motion, and swing leg motion, respectively; represents actual measured contact forces; represents a proportional matrix that regulates contact forces.

6. The hydraulic drive mobile work robot's end contact force control method according to claim 5, characterized by, The linear relationship expression of the system actual output with respect to the decision variables is: wherein: denotes a decision variable; denotes the actual output of the system; and is represented as: , is a selection matrix for the position constraint application; denotes the Jacobian matrix of the leg.

7. The hydraulic drive mobile work robot's end contact force control method according to claim 6, characterized by, The control architecture with respect to the decision variables, the expected output and the system actual output is specifically: where the decision variables of the control system are ; where, is a positive definite matrix, which is used to set the priority of the robot tasks to avoid the failure of the working tasks caused by task conflicts; is a positive definite matrix, which is used to minimize the system input ; , is the upper and lower bounds of the decision variables ; represents the Jacobian matrix containing the motion of the end of the mechanical arm and the end of the leg; represents the system inequality constraints containing the friction stack and joint limits.

8. A hydraulic drive mobile work robot end contact force control system characterized by: comprising: a state description module configured to define a coordinate system to describe the state of the quadruped robot; a robot floating base dynamics model construction module configured to consider the kinematic contact constraints of the force and torque of the mechanical arm work end and the foot end contact constraints of the robot, and obtain a robot floating base dynamics model based on the contact constraints; a control architecture with respect to the decision variables, the expected output and the system actual output is specifically: The expected output planning module is configured to decompose the interactive work task into a motion control subtask and a force control subtask, wherein the motion control subtask is planned in a proportional differential control mode to plan an expected acceleration, and the force control subtask is obtained by a force control strategy based on direct force feedback to plan an expected output; The linear relationship expression establishing module is configured to define decision variables of the control system, express the system actual output and the decision variables as a linear relationship, determine a linear relationship expression of the system actual output with respect to the decision variables based on a robot floating base dynamics model, a kinematic contact constraint of force and torque of a work end of the robot arm, and a foot end contact constraint, and determine a linear relationship expression of the system actual output with respect to the decision variables based on the robot floating base dynamics model, the kinematic contact constraint of force and torque of the work end of the robot arm, and the foot end contact constraint. The decision variable solving module is configured to design a control architecture with respect to the robot end contact force, solve the decision variables by using a quadratic optimization method based on the linear relationship expression of the system actual output with respect to the decision variables, and adjust the control decision variables to make the system actual output tend to the expected output. The force control module is configured to perform force control on the robot based on the solved decision variables.

9. A computer-readable storage medium having stored thereon a program, characterized in that, The program is executed by the processor to implement the steps in the end contact force control method of the hydraulic drive mobile work robot according to any one of claims 1-7.

10. An electronic device comprising a memory, a processor, and a program stored in the memory and capable of running on the processor, characterized by The processor executes the program to implement the steps in the end contact force control method of the hydraulic drive mobile work robot according to any one of claims 1-7.

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