A four-legged robot single leg sliding mode control method based on an interference observer

Abstract

The present application relates to a kind of four-legged robot single leg sliding mode control method based on interference observer, belong to robot control technical field.First, the trajectory of four-legged robot single leg in swing phase is established;Then, the kinematic model of four-legged robot single leg is established, to realize the conversion of foot target position and corresponding joint angle;On this basis, non-singular terminal sliding mode controller is designed to deal with the dynamics control under the condition of no interference;Finally, combined with sliding mode controller and interference estimation, the final composite control strategy is designed, the stable tracking of robot joint angle is realized, so as to improve the anti-interference performance of single leg system.The present application utilizes the combination of finite time interference observer and non-singular terminal sliding mode controller, designs a kind of composite controller, to improve the foot trajectory tracking accuracy and system robustness of four-legged robot, eliminate the uncertainty caused by external disturbance and modeling error suffered by robot.

Description

Technical Field

[0001] This invention belongs to the field of robot control technology and relates to a single-leg sliding mode control method for a quadruped robot based on an interference observer. Background Technology

[0002] Quadruped robots, due to their advantages of good stability and strong adaptability, outperform traditional wheeled or tracked robots in complex terrain. With the development of robotics technology, achieving stable control of quadruped robots has become a key research focus. Accurate tracking of foot trajectories is crucial. Traditional foot trajectory tracking control methods, such as proportional-derivative (PD) controllers based on virtual models, often struggle to simultaneously achieve tracking accuracy and robustness of the control system when faced with complex external disturbances and uncertainties. Sliding mode control, as a nonlinear control method, is widely used in robot control due to its strong robustness to system parameter uncertainties and external disturbances. However, traditional sliding mode control methods have limited convergence and anti-interference capabilities, and terminal sliding mode suffers from singularity issues. To address this, the Non-Singular Terminal Sliding Mode Controller (NTSMC) has been proposed. By designing special sliding surfaces, it enables the system state to converge within a finite time, thereby improving the response speed and accuracy of the control system. However, when NTSMC is used alone, it still cannot completely eliminate the influence of external disturbances on the system. To further enhance the robustness of single-leg trajectory tracking in quadruped robots, the Finite Time Disturbance Observer (FTDO) serves as an effective compensation strategy, capable of estimating and compensating for external disturbances in real time. Combining the FTDO with a non-singular end-of-arm sliding mode controller can better handle foot trajectory tracking tasks in complex environments, improving system stability and control accuracy. Therefore, to meet the requirements of single-leg trajectory tracking in quadruped robots, a control method combining the FTDO and non-singular end-of-arm sliding mode controller needs to be proposed to achieve higher accuracy and robustness in foot trajectory tracking control. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a single-leg sliding mode control method for quadruped robots based on a disturbance observer. By combining a finite-time disturbance observer with a non-singular terminal sliding mode controller, a composite controller is designed to improve the accuracy of foot trajectory tracking and system robustness of the quadruped robot, and to eliminate uncertainties caused by external disturbances and modeling errors.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A single-leg sliding mode control method for a quadruped robot based on an interference observer includes the following steps:

[0006] Establish the foot trajectory of a quadruped robot's single leg during the swinging phase;

[0007] Establish a kinematic model of a single leg of a quadruped robot to realize the conversion between the target position of the foot and the corresponding joint angle;

[0008] Establish a dynamic model of a single leg of a quadruped robot;

[0009] Establish a non-singular sliding mode controller for a single leg of a quadruped robot under interference-free conditions;

[0010] Estimating unknown disturbances in the system using a finite-time disturbance observer;

[0011] Design a single-leg composite controller for a quadruped robot under interference conditions to achieve stable tracking of the robot's preset joint angles.

[0012] The steps for establishing a non-singular sliding mode controller for a single leg of a quadruped robot under interference-free conditions are as follows:

[0013] The single-leg composite controller of the quadruped robot can be represented as a dynamic model based on joint angles, as shown in the following formula:

[0014]

[0015] in,

[0016] Joint torque;

[0017] It is a positive definite symmetric inertial matrix;

[0018] It is a matrix composed of centrifugal force and Coriolis force;

[0019] The gravity matrix;

[0020] The expected joint acceleration;

[0021] For angle tracking error: ;

[0022] in, For the ideal angle of tracking, , , , These are the rotation angles of the hip, thigh, and calf joints, respectively.

[0023] , , For positive integers, ;

[0024] For sliding surfaces: ;

[0025] in, This is the first derivative of the angle tracking error;

[0026] The estimated value of system interference: ;

[0027] in, This is the gain coefficient. , , The joint angular velocity, The auxiliary state vector introduced in the finite-time disturbance observer is expressed by the following formula: ;

[0028] Under the condition of no interference, the single-leg controller of the quadruped robot is a non-singular end sliding mode controller, which can be represented by a dynamic model based on joint angles, as shown in the following formula:

[0029] .

[0030] The steps for designing a single-leg composite controller for a quadruped robot under interference conditions to achieve stable tracking of preset joint angles of the robot are as follows:

[0031] Under disturbance conditions, the dynamic equation of a single leg of a quadruped robot is expressed as follows:

[0032]

[0033] in, , , This indicates the uncertainty of the system model parameters. Let be the nominal positive definite symmetric inertial matrix.

[0034] The nominal matrix consists of centrifugal force and Coriolis force. For the nominal gravity matrix, External interference;

[0035] Concentrated disturbances consisting of model uncertainty, joint friction, and load variation. It can be expressed as the following formula:

[0036]

[0037] Combining an observer with a non-singular terminal sliding mode controller, the single-leg composite controller of the quadruped robot is represented by a dynamic model based on joint angles, as shown in the following formula:

[0038]

[0039] The following formula is further obtained:

[0040] .

[0041] The single leg of the quadruped robot consists of three links connected to the joints of the body: the hip, the thigh, and the lower leg. These three links constitute corresponding joints. The hip joint is responsible for the left-right movement of the single leg of the quadruped robot, while the thigh and lower leg joints are responsible for the forward-backward movement of the single leg of the quadruped robot.

[0042] The steps for establishing the foot trajectory of a single leg of a quadruped robot during the swinging phase are as follows:

[0043] The trajectory of the foot of the quadruped robot during the swinging phase is established by the following formula:

[0044]

[0045] in, For the foot end Direction and trajectory;

[0046] For the foot end Direction and trajectory;

[0047] For the foot at Initial position in the direction;

[0048] The duration of the foot trajectory;

[0049] For the foot at End position in the direction;

[0050] For the foot at Initial velocity in the direction;

[0051] This represents the termination time of the foot's trajectory;

[0052] For the foot at Initial position in the direction;

[0053] For the foot at The height of the intermediate control point in the direction.

[0054] The step of establishing a kinematic model of a single leg of a quadruped robot to achieve the conversion between the target position of the foot and the corresponding joint angle is as follows:

[0055] Let the coordinate system of the hip joint be {1}, the coordinate system of the thigh joint be {2}, the coordinate system of the lower leg joint be {3}, the coordinate system of the foot end be {4}, and the coordinate system of the base be {0}. The origins of coordinate systems {0}, {1}, and {2} are set on the axes of the fuselage joint and the thigh joint. The relationship between the angles of the foot end, with the origin of the foot end coordinate system {4}, and each joint is expressed by the following formula:

[0056]

[0057]

[0058] in, , , The foot ends are respectively at x , y , Degrees of freedom in direction; , , These are the lengths of the hip, thigh, and calf joints, respectively.

[0059] The inverse kinematics equations for a single leg of the quadruped robot are established, expressed as follows:

[0060]

[0061] in, The foot is defined as a preset trajectory on each coordinate axis. The equivalent height coordinates obtained by coordinate transformation during the inverse kinematics solution process for the pre-defined trajectory of the foot are calculated as follows:

[0062]

[0063]

[0064]

[0065] .

[0066] The steps for establishing the dynamic model of a single leg of the quadruped robot are as follows:

[0067] The dynamic equation model of a single leg of a quadruped robot is established, expressed as the following formula:

[0068]

[0069] in, For the mass matrix parameters, The parameters are the Coriolis force and centripetal force matrix parameters. These are the parameters of the gravity matrix. For the torque of each joint; , , These are the joint angular accelerations of the hip, thigh, and lower leg, respectively. , , These are the joint angular velocities of the hip, thigh, and lower leg, respectively; the calculation process is as follows:

[0070]

[0071]

[0072]

[0073]

[0074]

[0075] in, These are the moments of inertia of the hip, thigh, and calf connecting rods, respectively. For the mass of each link, Let be the distance from the center of mass of each link to the coordinate system in which the link is located. This represents the distance from the center of mass of each link to the coordinate system of the link above it.

[0076] The beneficial effects of this invention are as follows:

[0077] By combining a finite-time disturbance observer with a non-singular terminal sliding mode controller, the tracking accuracy and robustness of the quadruped robot's foot trajectory in complex environments are effectively improved. This composite control strategy eliminates uncertainties caused by external disturbances and modeling errors, achieving stable tracking of the robot's joint angles. By establishing detailed kinematic and dynamic models of a single leg of the quadruped robot, the conversion between the target foot position and the corresponding joint angle can be accurately realized, providing a solid foundation for subsequent control strategies.

[0078] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0079] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0080] Figure 1 This is a three-dimensional spatial diagram of the trajectory of the right foreleg of a quadruped robot according to a specific embodiment of the present invention.

[0081] Figure 2 This is a schematic diagram of a single leg of a quadruped robot according to a specific embodiment of the present invention;

[0082] Figure 3 This is a control flowchart of a single-leg composite controller for a quadruped robot according to a specific embodiment of the present invention.

[0083] Figure 4 This is a three-dimensional spatial comparison diagram of foot trajectory during the control process of a virtual model controller and a composite controller according to a specific embodiment of the present invention;

[0084] Figure 5 This invention relates to a specific embodiment of foot trajectory control during a process based on a virtual model controller and a composite controller. Directional comparison chart;

[0085] Figure 6 This invention relates to a specific embodiment of foot trajectory control during a process based on a virtual model controller and a composite controller. y Directional comparison chart;

[0086] Figure 7 This invention relates to a specific embodiment of foot trajectory control during a process based on a virtual model controller and a composite controller. Directional comparison chart;

[0087] Figure 8 This is a diagram showing the interference estimation curve of a finite-time interference observer according to a specific embodiment of the present invention. Detailed Implementation

[0088] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0089] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0090] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0091] This invention proposes a single-leg sliding mode control method for quadruped robots based on a disturbance observer. By combining a finite-time disturbance observer with a non-singular terminal sliding mode controller, a composite controller is designed to improve the tracking accuracy of the quadruped robot's foot trajectory and the system's robustness, and to eliminate uncertainties caused by external disturbances and modeling errors.

[0092] First, the foot trajectory of a single leg of the quadruped robot during the swinging phase is established. Next, a kinematic model of the single leg is built to realize the conversion between the target foot position and the corresponding joint angle. Then, a dynamic model of the single leg is established. Based on this, a non-singular end effector sliding mode controller is designed to handle dynamic control under disturbance-free conditions. Finally, combining the sliding mode controller and disturbance estimation, a final composite control strategy is designed to achieve stable tracking of the robot's joint angles, thereby improving the disturbance rejection performance of the single-leg system. A specific implementation includes the following steps:

[0093] Step 1: Establish the foot trajectory of a single leg of the quadruped robot during the swinging phase:

[0094] Gait refers to the sequence of movements of the legs of a quadruped robot in time and space, with a periodic gait typically used on flat ground. The gait cycle refers to the process of one heel striking the ground and then the other heel striking the ground again during walking, usually divided into two phases: the support phase and the swing phase. The support phase is when the foot touches the ground and bears the body weight, while the swing phase is when the foot moves in the air without touching the ground.

[0095] This invention mainly relates to a control method for the oscillating phase. Please refer to [link / reference]. Figure 1 This is a three-dimensional spatial diagram of the preset trajectory of the right foreleg of a quadruped robot according to a specific embodiment of the present invention. x The axis indicates the direction of travel. ，y The axis indicates the direction of lateral movement. ，z The axis represents the height direction. The preset foot trajectory in this embodiment is the trajectory during the swing phase, expressed by the following formula:

[0096]

[0097] in, For the foot end Direction and trajectory; For the foot end Direction and trajectory; For the foot at Initial position in the direction; The duration of the foot trajectory; For the foot at End position in the direction; For the foot at Initial velocity in the direction; This represents the termination time of the foot's trajectory; For the foot at Initial position in the direction; For the foot at The height of the intermediate control point in the direction.

[0098] Step 2: Establish a single-leg kinematic model of the quadruped robot:

[0099] Please see Figure 2 This is a schematic diagram of a single leg of a quadruped robot according to a specific embodiment of the present invention. The single leg of the quadruped robot is mainly composed of three links connected to the joints of the robot body: the hip, the thigh, and the lower leg. These three links constitute corresponding joints. Among them, the hip joint is mainly responsible for the left-right movement of the single leg of the quadruped robot, while the thigh and lower leg joints are responsible for the forward-backward movement of the single leg of the quadruped robot.

[0100] like Figure 2As shown, the hip joint coordinate system is {1}, the thigh joint coordinate system is {2}, the lower leg joint coordinate system is {3}, and the foot coordinate system is {4}. Furthermore, the {0} coordinate system is defined as the base coordinate system. To simplify the homogeneous transformation matrix between the coordinate systems, the origins of coordinate systems {0}, {1}, and {2} are all placed on the axes of the body joint and the thigh joint. The relationship between the foot of the quadruped robot, with coordinate system {4} as its origin, and the angles of each joint is expressed by the following formula:

[0101]

[0102]

[0103] in, For the foot at Degrees of freedom in direction, For the foot at Degrees of freedom in direction, For the foot at Degrees of freedom in direction; The length of the hip joint of the quadruped robot's leg. The length of the thigh joint of the quadruped robot's leg. The length of the lower leg joint of the quadruped robot; This refers to the rotation angle of the hip joint of the quadruped robot's leg. This refers to the rotation angle of the thigh joint of the quadruped robot's leg. This refers to the rotation angle of the lower leg joint of the quadruped robot.

[0104] To convert the preset foot trajectory into joint angles for control, the inverse kinematics equation for a single leg of the quadruped robot is expressed as the following formula:

[0105]

[0106] in, The foot follows a preset trajectory on each coordinate axis. The equivalent height coordinates are obtained through coordinate transformation during the inverse kinematics solution process for the pre-defined trajectory of the foot. The calculation process for other parameters is as follows:

[0107]

[0108]

[0109]

[0110]

[0111] Step 3: Establish the dynamic equation model of a single leg of the quadruped robot based on the joint parameters, expressed as the following formula:

[0112]

[0113] in, For the mass matrix parameters, The parameters are the Coriolis force and centripetal force matrix parameters. These are the parameters of the gravity matrix. For the torque of each joint; , , These are the joint angular accelerations of the hip, thigh, and lower leg of the quadruped robot, respectively. , , These are the joint angular velocities of the hip, thigh, and lower leg of the quadruped robot, respectively.

[0114] The calculation process for each parameter is as follows:

[0115]

[0116]

[0117]

[0118]

[0119]

[0120] in, Let represent the moments of inertia of the hip, thigh, and lower leg links of the quadruped robot, respectively. Indicates the mass of each link. This represents the distance from the center of mass of each link to the coordinate system in which the link is located. This represents the distance from the center of mass of each link to the coordinate system of the link above it.

[0121] Step 4: Design a single-leg composite controller for the quadruped robot:

[0122] Since the output of the quadruped robot's single-leg composite controller is the joint torque of the quadruped robot's hip, thigh, and lower leg, the quadruped robot's single-leg composite controller can be represented as a dynamic model based on joint angles, as shown in the following formula:

[0123]

[0124] in, Joint torque; It is a positive definite symmetric inertial matrix; It is a matrix composed of centrifugal force and Coriolis force; The gravity matrix; The expected joint acceleration;

[0125] For angle tracking error, ;in, For the ideal angle of tracking, ;

[0126] , , For positive integers, ;

[0127] For sliding surfaces: ;in, This is the first derivative of the angle tracking error;

[0128] This is an estimate of the system interference.

[0129] The design of a single-leg composite controller for a quadruped robot includes the following steps:

[0130] 1) Design a single-leg non-singular sliding mode controller for a quadruped robot under interference-free conditions:

[0131] Considering the absence of interference, based on the single-leg dynamics model of the quadruped robot, the single-leg composite controller of the quadruped robot is a non-singular end sliding mode controller, expressed as a dynamics model based on joint angles, as shown in the following formula:

[0132]

[0133] 2) Design a finite-time disturbance observer:

[0134] The robustness of the control system can be improved by estimating unknown disturbances in the system using a finite-time disturbance observer. First, to facilitate observer design, a vector is defined. It can be expressed as the following formula:

[0135]

[0136] in, The joint angular velocity, This is an auxiliary state vector introduced in a finite-time disturbance observer. The derivative value is expressed by the following formula:

[0137]

[0138] in, The estimated value of the system disturbance is expressed by the following formula:

[0139]

[0140] in, This is the gain coefficient. .

[0141] 3) Design a single-leg composite controller for a quadruped robot under interference conditions:

[0142] Considering the presence of disturbances, the dynamic equation of a single leg of a quadruped robot can be expressed as follows:

[0143]

[0144] in, , , This indicates the uncertainty of the system model parameters; Let be the nominal positive definite symmetric inertial matrix.

[0145] The nominal matrix consists of centrifugal force and Coriolis force. For the nominal gravity matrix, External interference.

[0146] Concentrated disturbances consisting of model uncertainty, joint friction, and load variation. It can be expressed as the following formula:

[0147]

[0148] Combining an observer with a non-singular terminal sliding mode controller, the single-leg composite controller of the quadruped robot is represented by a dynamic model based on joint angles, as shown in the following formula:

[0149]

[0150] The following formula is further obtained:

[0151]

[0152] Please see Figure 3 The diagram below illustrates the control flow of a quadruped robot single-leg composite controller according to a specific embodiment of the present invention, demonstrating the working principle of single-leg end-effector trajectory tracking: First, a trajectory generator is used to calculate the expected trajectory of the foot; then, the inverse kinematics equation of the single leg is used to convert the expected trajectory into angular rotation of each joint; next, the difference between the expected angle and the actual angle is used to obtain the angle error, and a non-singular end-effector sliding mode controller is built by combining four sets of robot single-leg dynamic equations; based on this, a finite-time disturbance observer is established to estimate the unmodeled dynamics and disturbances of the system, and the final composite control strategy is designed.

[0153] Please see Figure 4 This is a three-dimensional spatial comparison diagram of foot trajectory during the control process of a virtual model controller and a composite controller according to a specific embodiment of the present invention; please refer to [link / reference]. Figures 5-7 This is a specific embodiment of the present invention regarding foot trajectory during the control process based on a virtual model controller and a composite controller. , y , Directional comparison chart.

[0154] 0.1 seconds after system startup, disturbances are simultaneously applied to both the virtual model-based controller and the composite controller, and the results are compared. Figures 4-7 The tracking performance of each controller in the model shows that the virtual model-based controller has a large trajectory tracking error and is difficult to achieve the desired effect of accurately tracking the curve. In contrast, the composite controller can accurately track the desired curve even after being subjected to interference, and its trajectory tracking performance remains good. Therefore, the composite controller in this embodiment can effectively suppress interference and improve the robustness of the system.

[0155] Please see Figure 8 The figure shows the interference estimation curves of a finite-time interference observer according to a specific embodiment of the present invention. It can be seen from the external interference curves and the estimated disturbance curves of each joint that the joint torques estimated by the finite-time interference observer basically coincide with the given joint torque curves. Therefore, the estimation system of the finite-time interference observer proposed in this invention has good unknown interference estimation performance.

[0156] This invention combines a finite-time disturbance observer with a non-singular terminal sliding mode controller, effectively improving the foot trajectory tracking accuracy and system robustness of a quadruped robot in complex environments. This composite control strategy eliminates uncertainties caused by external disturbances and modeling errors, achieving stable tracking of the robot's joint angles. By establishing detailed kinematic and dynamic models of a single leg of the quadruped robot, the conversion between the target foot position and the corresponding joint angle can be accurately realized, providing a solid foundation for subsequent control strategies. Experimental results show that even under disturbance, the composite controller maintains good trajectory tracking performance, significantly outperforming traditional virtual model-based control methods. The disturbance estimation curve of the finite-time disturbance observer is highly consistent with the actual disturbance, further verifying the effectiveness and accuracy of the proposed method.

[0157] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A single-leg sliding mode control method for a quadruped robot based on an interference observer, characterized in that, Includes the following steps: Establish the foot trajectory of a quadruped robot's single leg during the swinging phase; Establish a kinematic model of a single leg of a quadruped robot to realize the conversion between the target position of the foot and the corresponding joint angle; Establish a dynamic model of a single leg of a quadruped robot; Establish a non-singular sliding mode controller for a single leg of a quadruped robot under interference-free conditions; Estimating unknown disturbances in the system using a finite-time disturbance observer; Design a single-leg composite controller for a quadruped robot under interference conditions to achieve stable tracking of preset joint angles of the robot; The steps for establishing a non-singular sliding mode controller for a single leg of a quadruped robot under interference-free conditions are as follows: The single-leg composite controller of the quadruped robot can be represented as a dynamic model based on joint angles, as shown in the following formula: in, Joint torque; It is a positive definite symmetric inertial matrix; It is a matrix composed of centrifugal force and Coriolis force; The gravity matrix; The expected joint acceleration; For angle tracking error: ; in, For the ideal angle of tracking, , , , These are the rotation angles of the hip, thigh, and calf joints, respectively. , , For positive integers, ; For sliding surfaces: ; in, This is the first derivative of the angle tracking error; The estimated value of system interference: ; in, This is the gain coefficient. , , The joint angular velocity, The auxiliary state vector introduced in the finite-time disturbance observer is expressed by the following formula: ; Under the condition of no interference, the single-leg controller of the quadruped robot is a non-singular end sliding mode controller, which can be represented by a dynamic model based on joint angles, as shown in the following formula: ； The steps for designing a single-leg composite controller for a quadruped robot under interference conditions to achieve stable tracking of preset joint angles of the robot are as follows: Under disturbance conditions, the dynamic equation of a single leg of a quadruped robot is expressed as follows: in, , , This indicates the uncertainty of the system model parameters. Let be the nominal positive definite symmetric inertial matrix. The nominal matrix consists of centrifugal force and Coriolis force. For the nominal gravity matrix, External interference; Concentrated disturbances consisting of model uncertainty, joint friction, and load variation. It can be expressed as the following formula: Combining an observer with a non-singular terminal sliding mode controller, the single-leg composite controller of the quadruped robot is represented by a dynamic model based on joint angles, as shown in the following formula: The following formula is further obtained: 。 2. The single-leg sliding mode control method for a quadruped robot based on an interference observer according to claim 1, characterized in that: The single leg of the quadruped robot consists of three links connected to the joints of the body: the hip, the thigh, and the lower leg. These three links constitute corresponding joints. The hip joint is responsible for the left-right movement of the single leg of the quadruped robot, while the thigh and lower leg joints are responsible for the forward-backward movement of the single leg of the quadruped robot.

3. The method for single-leg sliding mode control of a quadruped robot based on an interference observer according to claim 2, characterized in that, The steps for establishing the foot trajectory of a single leg of a quadruped robot during the swinging phase are as follows: The trajectory of the foot of the quadruped robot during the swinging phase is established by the following formula: in, For the foot end Direction and trajectory; For the foot end Direction and trajectory; For the foot at Initial position in the direction; The duration of the foot trajectory; For the foot at End position in the direction; For the foot at Initial velocity in the direction; This represents the termination time of the foot's trajectory; For the foot at Initial position in the direction; For the foot at The height of the intermediate control point in the direction.

4. The single-leg sliding mode control method for a quadruped robot based on an interference observer according to claim 3, characterized in that, The step of establishing a kinematic model of a single leg of a quadruped robot to achieve the conversion between the target position of the foot and the corresponding joint angle is as follows: Let the coordinate system of the hip joint be {1}, the coordinate system of the thigh joint be {2}, the coordinate system of the lower leg joint be {3}, the coordinate system of the foot end be {4}, and the coordinate system of the base be {0}. The origins of coordinate systems {0}, {1}, and {2} are set on the axes of the fuselage joint and the thigh joint. The relationship between the angles of the foot end, with the origin of the foot end coordinate system {4}, and each joint is expressed by the following formula: in, , , The foot ends are respectively at x , y , Degrees of freedom in direction; , , These are the lengths of the hip, thigh, and calf joints, respectively. The inverse kinematics equations for a single leg of the quadruped robot are established, expressed as follows: in, The foot is defined as a preset trajectory on each coordinate axis. The equivalent height coordinates obtained by coordinate transformation during the inverse kinematics solution process for the pre-defined trajectory of the foot are calculated as follows: 。 5. The single-leg sliding mode control method for a quadruped robot based on an interference observer according to claim 4, characterized in that, The steps for establishing the dynamic model of a single leg of the quadruped robot are as follows: The dynamic equation model of a single leg of a quadruped robot is established, expressed as the following formula: in, For the mass matrix parameters, The parameters are the Coriolis force and centripetal force matrix parameters. These are the parameters of the gravity matrix. For the torque of each joint; , , These are the joint angular accelerations of the hip, thigh, and lower leg, respectively. , , These are the joint angular velocities of the hip, thigh, and lower leg, respectively; the calculation process is as follows: in, These are the moments of inertia of the hip, thigh, and calf connecting rods, respectively. For the mass of each link, Let be the distance from the center of mass of each link to the coordinate system in which the link is located. This represents the distance from the center of mass of each link to the coordinate system of the link above it.

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