Trajectory tracking robust control method and system for three-degree-of-freedom hydraulic mechanical arm

Abstract

The invention discloses a trajectory tracking robust control method and system for a three-degree-of-freedom hydraulic mechanical arm, and relates to the technical field of automatic control. The method comprises the steps that a dynamic model is built for the three-degree-of-freedom hydraulic mechanical arm; according to the dynamic model and an output force model of the hydraulic valve control cylinder system, modeling is conducted on a hydraulic actuator, and a second-order model is obtained; designing a super-spiral sliding mode controller for the second-order model; determining an error angle between the expected joint angle and an actual joint angle of a joint in the three-degree-of-freedom hydraulic mechanical arm; inputting the error angle into a super-spiral sliding mode controller to obtain a control quantity; and according to the control quantity, the system uncertainty parameters and the external disturbance parameters, a hydraulic valve control cylinder system is controlled to move, and then a hydraulic actuator is driven to enable the three-degree-of-freedom hydraulic mechanical arm to move. According to the method, the system uncertainty and the external disturbance are hidden in the high-order derivative of the control law through the super-spiral sliding mode controller, the buffeting amplitude is remarkably reduced, the anti-interference capability is improved, and the robustness is kept.

Description

Technical Field

[0001] The present application relates to the field of automatic control technology, and in particular to a trajectory tracking robust control method and system for a three-degree-of-freedom hydraulic manipulator. Background Art

[0002] At present, there are still great challenges in the high-precision tracking control method of the end position and trajectory of multi-degree-of-freedom hydraulic manipulators. First of all, the hydraulic drive manipulator system is a complex system with high nonlinearity. The design and use of various controllers often require a very precise passive system. This precision is generally reflected in two aspects: first, it comes from the precision of internal model parameters, including such as manipulator parameters, hydraulic system parameters, kinematic and dynamic parameters, etc.; second, it comes from the precision of external disturbance assessment of the system, including such as ambient temperature, unexpected vibration, contact force mutation, etc. Current technologies such as traditional controller PID, linearized synovial SMC; optimal controller linear quadratic regulation, model predictive control and other control methods all need to rely on accurate hydraulic actuator models, and the bulk modulus and flow coefficient of the oil are easily affected by factors such as temperature and pollution, resulting in model mismatch. Secondly, hydraulic manipulators usually need to be equipped with high-precision velocity sensors to obtain angular velocity signals, but such sensors are expensive and easily interfered with in oily and vibrating environments. At the same time, when the manipulator is under heavy load or external disturbance, the transmission control method does not explicitly compensate for hydraulic dynamics (such as pressure fluctuations and flow nonlinearity), which leads to increased tracking errors or instability, reducing the life of hydraulic components. Finally, traditional synovial controllers rely on the switching term of the sign function sign(s), which causes high-frequency jitter in control inputs such as (servo valve drive voltage) and accelerates mechanical wear of the system. Summary of the invention

[0003] The main purpose of the embodiments of the present application is to propose a trajectory tracking robust control method and system for a three-degree-of-freedom hydraulic manipulator to improve interference resistance and robustness.

[0004] To achieve the above object, one aspect of an embodiment of the present application proposes a trajectory tracking robust control method for a three-degree-of-freedom hydraulic manipulator, the method comprising the following steps:

[0005] Constructing a dynamic model for a three-degree-of-freedom hydraulic mechanical arm; wherein the three-degree-of-freedom hydraulic mechanical arm is driven by a hydraulic valve-controlled cylinder system;

[0006] Modeling the hydraulic actuator according to the dynamic model and using the output force model of the hydraulic valve-controlled cylinder system to obtain a second-order model;

[0007] Designing a super-helical synovial controller for the second-order model;

[0008] determining an error angle between a desired joint angle and an actual joint angle of a joint in the three-degree-of-freedom hydraulic robotic arm;

[0009] Inputting the error angle into the super spiral synovial controller to obtain a control amount;

[0010] The movement of the hydraulic valve-controlled cylinder system is controlled according to the control quantity, system uncertainty parameters and external disturbance parameters, thereby driving the hydraulic actuator to move the three-degree-of-freedom hydraulic mechanical arm.

[0011] In some embodiments, constructing a dynamic model for a three-degree-of-freedom hydraulic mechanical arm comprises the following steps:

[0012] The dynamic model of the three-degree-of-freedom hydraulic manipulator is constructed using the Lagrangian method:

[0013]

[0014] Where θ=[θ 1 ,θ 2 θ 3 ] T is the joint angle; τ=[τ 1 ,τ 2 ,τ 3 ] T is the joint torque output by the hydraulic actuator; M is the joint space inertia force matrix; C is the Coriolis force and centrifugal force coupling matrix; G is the gravity load; F f is the friction of the system.

[0015] In some embodiments, modeling the hydraulic actuator according to the dynamic model and using the output force model of the hydraulic valve-controlled cylinder system to obtain a second-order model includes the following steps:

[0016] The actual joint angle is obtained by using angle encoders arranged at each rotating joint of the three-degree-of-freedom hydraulic mechanical arm; the hydraulic pressure is respectively obtained by using pressure sensors arranged at the oil inlet and oil return ports of the hydraulic cylinder and the pressure drop at the valve port is obtained by difference; the displacement of the servo valve core is measured by using a displacement sensor arranged inside the servo valve;

[0017] The output force model of the hydraulic valve-controlled cylinder system is constructed as follows:

[0018]

[0019] Among them, K hi is the gain coefficient of the hydraulic valve-controlled cylinder system, x vi is the servo valve core displacement, ΔP i is the valve port pressure drop, B hi is the hydraulic damping coefficient, fvi is the nonlinear friction force; is the actual joint angular velocity;

[0020] Defining the state variables of the system and then constructing the second-order model according to the dynamic model;

[0021] The state variables are:

[0022]

[0023] The second-order model is:

[0024]

[0025] In some embodiments, designing a super spiral synovial controller for the second-order model comprises the following steps:

[0026] The synovial surface of the superhelical synovial controller is defined as:

[0027] s=[s 1 ,s 2 ,s 3 ] T ;

[0028] The sliding surface is expressed as a linear combination of tracking errors:

[0029]

[0030] e i =θ i -θ i,d ;

[0031] Among them, i=[1,2,3]; θ i,d is the expected joint angle; e i is the error joint angle; i >0 is the sliding film surface slope parameter, which is used to determine the error convergence speed;

[0032] The input of the superhelical synovial controller is defined to include an equivalent control term and a superhelical compensation term;

[0033] τ=τ eq +τ sts ;

[0034] Where, τ represents the input of the superhelical synovial controller, τ eq is the equivalent control term used to offset the nominal dynamics; τ sts is the superhelix compensation term, used to compensate for the system uncertainty parameter and the external disturbance parameter;

[0035]

[0036] Where α = diag(α 1 ,α 2 ,α 3 ), β=diag(β 1 ,β 2 ,β 3 ) is the gain coefficient of the superhelical synovial controller;

[0037] Define the extended state variable as:

[0038] z i =∫sign(s i )dt;

[0039] Then the control law of the super spiral sliding film controller is obtained as follows:

[0040]

[0041] In some embodiments, determining the error angle between the expected joint angle and the actual joint angle of the joint in the three-degree-of-freedom hydraulic mechanical arm comprises the following steps:

[0042] Obtaining the expected joint angle;

[0043] Obtaining the actual joint angle through an angle encoder;

[0044] The expected joint angle is subtracted from the actual joint angle to obtain the error angle.

[0045] In some embodiments, the step of inputting the error angle into the super spiral synovial controller to obtain a control amount comprises the following steps:

[0046] Determining the joint velocity corresponding to the actual joint angle by a synovial membrane observer;

[0047] The error angle and the joint speed are input into the super spiral synovial controller to obtain the control amount.

[0048] In some embodiments, the method further comprises the following steps:

[0049] All sensors in the three-degree-of-freedom hydraulic mechanical arm are synchronized in hardware through a unified clock source PTP protocol.

[0050] To achieve the above object, another aspect of the embodiment of the present application provides a trajectory tracking robust control system for a three-degree-of-freedom hydraulic manipulator, the control system comprising:

[0051] A dynamic modeling module, used to construct a dynamic model for a three-degree-of-freedom hydraulic mechanical arm; wherein the three-degree-of-freedom hydraulic mechanical arm is driven by a hydraulic valve-controlled cylinder system;

[0052] A second-order modeling module, used to model the hydraulic actuator according to the dynamic model and the output force model of the hydraulic valve-controlled cylinder system to obtain a second-order model;

[0053] A controller design module, used for designing a super spiral synovial controller for the second-order model;

[0054] an error determination module for determining an error angle between a desired joint angle and an actual joint angle of a joint in the three-degree-of-freedom hydraulic mechanical arm;

[0055] A control amount determination module, used for inputting the error angle into the super spiral synovial controller to obtain a control amount;

[0056] A drive control module is used to control the movement of the hydraulic valve-controlled cylinder system according to the control quantity, system uncertainty parameters and external disturbance parameters, and then drive the hydraulic actuator to move the three-degree-of-freedom hydraulic mechanical arm.

[0057] To achieve the above objective, another aspect of an embodiment of the present application provides an electronic device, the electronic device comprising a memory and a processor, the memory storing a computer program, and the processor implementing the above method when executing the computer program.

[0058] To achieve the above objective, another aspect of an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program implements the above method when executed by a processor.

[0059] The embodiments of the present application include at least the following beneficial effects:

[0060] The present application can construct a dynamic model for a three-degree-of-freedom hydraulic mechanical arm; wherein the three-degree-of-freedom hydraulic mechanical arm is driven by a hydraulic valve-controlled cylinder system; the hydraulic actuator is modeled according to the dynamic model and the output force model of the hydraulic valve-controlled cylinder system to obtain a second-order model; a super-spiral synovial controller is designed for the second-order model; the error angle between the expected joint angle and the actual joint angle of the joint in the three-degree-of-freedom hydraulic mechanical arm is determined; the error angle is input into the super-spiral synovial controller to obtain the control quantity; the movement of the hydraulic valve-controlled cylinder system is controlled according to the control quantity, the system uncertainty parameter and the external disturbance parameter, thereby driving the hydraulic actuator to move the three-degree-of-freedom hydraulic mechanical arm. The present application uses a super-spiral synovial controller to hide the high-frequency switching system uncertainty parameters and external disturbance parameters in the high-order derivatives of the control law, significantly reducing the jitter amplitude and improving the anti-interference ability while maintaining robustness. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0062] Figure 1 A schematic flow chart of a trajectory tracking robust control method for a three-degree-of-freedom hydraulic manipulator provided in an embodiment of the present application;

[0063] Figure 2 A simplified diagram of the overall structure of a multi-degree-of-freedom hydraulic mechanical arm driven by a hydraulic valve-controlled cylinder system provided in an embodiment of the present application;

[0064] Figure 3 A diagram of components of a hydraulic valve-controlled cylinder system provided in an embodiment of the present application;

[0065] Figure 4 An example flow chart of a trajectory tracking robust control method for a three-degree-of-freedom hydraulic manipulator provided in an embodiment of the present application;

[0066] Figure 5 A block diagram of a closed-loop control system of a three-degree-of-freedom hydraulic manipulator based on a super-helical synovial membrane provided in an embodiment of the present application;

[0067] Figure 6 A schematic diagram of the structure of a trajectory tracking robust control system for a three-degree-of-freedom hydraulic manipulator provided in an embodiment of the present application;

[0068] Figure 7 A schematic diagram of the hardware structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0069] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the embodiments of the present application. They are only examples of devices and methods consistent with some aspects of the embodiments of the present application as detailed in the attached claims.

[0070] It is understood that the terms "first", "second", etc. used in this application can be used to describe various concepts in this article, but unless otherwise specified, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another concept. For example, without departing from the scope of the embodiment of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the words "if" and "if" as used herein can be interpreted as "at the time of" or "when" or "in response to determination".

[0071] The terms "at least one", "multiple", "each", "any", etc. used in this application, at least one includes one, two or more, multiple includes two or more, each refers to each of the corresponding multiple, and any refers to any one of the multiple.

[0072] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0073] Before describing the embodiments of the present application in detail, some related technologies involved in the embodiments of the present application are first described as follows:

[0074] In the application field of electro-hydraulic servo technology, hydraulic valve-controlled cylinder systems are widely used to drive the movement of actuator terminals, such as multi-degree-of-freedom hydraulic mechanical arm systems. In view of the following defects of existing control technology, the technical problems to be solved by this application are as follows:

[0075] Aiming at the problem of traditional controller's dependence on the strong nonlinear model of hydraulic system, that is, the high precision of hydraulic manipulator (manufacturing tolerance, assembly error), hydraulic actuator model (flow-pressure equation, friction model, etc.), and hydraulic system parameters (such as oil bulk modulus, flow coefficient), this design is based on adaptive gain super-helical sliding film control. By dynamically adjusting the controller gain (α, β), the model uncertainty is compensated to reduce the dependence on the precise model. At the same time, the high-order sliding mode algorithm and integral compensation term are used to hide the high-frequency switching in the high-order derivative of the control law, which significantly reduces the jitter amplitude while maintaining robustness.

[0076] In response to the high cost and noise sensitivity of traditional rotational joint speed measurement, that is, the cost of high-precision speed sensors is generally high and they are easily affected by noise in oily and vibrating environments, the synovial membrane observer integrated in this application only requires joint position signals to estimate joint speed in real time, avoiding direct measurement, reducing hardware costs, and suppressing noise effects through the Robin observation algorithm.

[0077] In order to improve the anti-disturbance capability of the hydraulic-mechanical arm coupling system, that is, when the hydraulic mechanical arm is under heavy load or external disturbance (such as sudden change in contact force), the traditional control method does not explicitly compensate for the hydraulic dynamics (such as pressure fluctuations, flow nonlinearity), which leads to increased tracking error or even instability. This application constructs a joint dynamics-hydraulic coupling model, embeds the hydraulic actuator pressure dynamic equation in the super-helical controller framework, and compensates for disturbances such as oil compressibility and valve port flow nonlinearity in real time.

[0078] Reference Figure 1 The embodiment of the present application provides a trajectory tracking robust control method for a three-degree-of-freedom hydraulic manipulator. The method may include but is not limited to S100 to S150, which are as follows:

[0079] S100: constructing a dynamic model for a three-degree-of-freedom hydraulic mechanical arm; wherein the three-degree-of-freedom hydraulic mechanical arm is driven by a hydraulic valve-controlled cylinder system;

[0080] S110: Modeling the hydraulic actuator according to the dynamic model and the output force model of the hydraulic valve-controlled cylinder system to obtain a second-order model;

[0081] S120: designing a super spiral synovial controller for the second-order model;

[0082] S130: Determine an error angle between a desired joint angle and an actual joint angle of a joint in the three-degree-of-freedom hydraulic mechanical arm;

[0083] S140: inputting the error angle into the super spiral synovial controller to obtain a control value;

[0084] S150: Controlling the movement of the hydraulic valve-controlled cylinder system according to the control quantity, system uncertainty parameters and external disturbance parameters, and then driving the hydraulic actuator to move the three-degree-of-freedom hydraulic mechanical arm.

[0085] Optionally, constructing a dynamic model for a three-degree-of-freedom hydraulic mechanical arm comprises the following steps:

[0086] The dynamic model of the three-degree-of-freedom hydraulic manipulator is constructed using the Lagrangian method:

[0087]

[0088] Where θ=[θ 1 ,θ 2 θ 3 ] T is the joint angle; τ=[τ 1 ,τ 2 ,τ 3 ] Tis the joint torque output by the hydraulic actuator; M is the joint space inertia force matrix; C is the Coriolis force and centrifugal force coupling matrix; G is the gravity load; E f is the friction of the system.

[0089] Optionally, modeling the hydraulic actuator according to the dynamic model and using the output force model of the hydraulic valve-controlled cylinder system to obtain a second-order model includes the following steps:

[0090] The actual joint angle is obtained by using angle encoders arranged at each rotating joint of the three-degree-of-freedom hydraulic mechanical arm; the hydraulic pressure is respectively obtained by using pressure sensors arranged at the oil inlet and oil return ports of the hydraulic cylinder and the pressure drop at the valve port is obtained by difference; the displacement of the servo valve core is measured by using a displacement sensor arranged inside the servo valve;

[0091] The output force model of the hydraulic valve-controlled cylinder system is constructed as follows:

[0092]

[0093] Among them, K hi is the gain coefficient of the hydraulic valve-controlled cylinder system, x vi is the servo valve core displacement, ΔP i is the valve port pressure drop, B hi is the hydraulic damping coefficient, f vi is the nonlinear friction force; is the actual joint angular velocity;

[0094] Defining the state variables of the system and then constructing the second-order model according to the dynamic model;

[0095] The state variables are:

[0096]

[0097] The second-order model is:

[0098]

[0099] Optionally, designing a super spiral synovial controller for the second-order model comprises the following steps:

[0100] The synovial surface of the superhelical synovial controller is defined as:

[0101] s=[s 1 ,s 2 ,s 3 ] T ;

[0102] The sliding surface is expressed as a linear combination of tracking errors:

[0103]

[0104] e i =θ i -θ i,d ;

[0105] Among them, i=[1,2,3]; θ i,d is the expected joint angle; e i is the error joint angle; i >0 is the sliding film surface slope parameter, which is used to determine the error convergence speed;

[0106] The input of the superhelical synovial controller is defined to include an equivalent control term and a superhelical compensation term;

[0107] τ=τ eq +τ sts ;

[0108] Where, τ represents the input of the superhelical synovial controller, τ eq is the equivalent control term used to offset the nominal dynamics; τ sts is the superhelix compensation term, used to compensate for the system uncertainty parameter and the external disturbance parameter;

[0109]

[0110] Where α = diag(α 1 ,α 2 ,α 3 ), β=diag(β 1 ,β 2 ,β 3 ) is the gain coefficient of the superhelical synovial controller;

[0111] Define the extended state variable as:

[0112] z i =∫sign(s i )dt;

[0113] Then the control law of the super spiral sliding film controller is obtained as follows:

[0114]

[0115] Optionally, determining the error angle between the expected joint angle and the actual joint angle of the joint in the three-degree-of-freedom hydraulic mechanical arm comprises the following steps:

[0116] Obtaining the expected joint angle;

[0117] Obtaining the actual joint angle through an angle encoder;

[0118] The expected joint angle is subtracted from the actual joint angle to obtain the error angle.

[0119] Optionally, the step of inputting the error angle into the super spiral synovial controller to obtain a control amount comprises the following steps:

[0120] Determining the joint velocity corresponding to the actual joint angle by a synovial membrane observer;

[0121] The error angle and the joint speed are input into the super spiral synovial controller to obtain the control amount.

[0122] Optionally, the method further comprises the following steps:

[0123] All sensors in the three-degree-of-freedom hydraulic mechanical arm are synchronized in hardware through a unified clock source PTP protocol.

[0124] Next, the solution of the embodiment of the present application will be introduced and explained in detail with reference to specific application examples.

[0125] ① In the process of completing this embodiment, the necessary components of the hydraulic valve-controlled cylinder system include: hydraulic cylinder, proportional valve, displacement sensor, pressure sensor, and angle encoder.

[0126] ②Configuration relationship: The proportional valve is connected to the rod chamber and rodless chamber of the hydraulic cylinder through a pipeline loop; the displacement sensor is arranged inside the servo valve, the pressure sensor is arranged near the oil inlet and outlet of the hydraulic cylinder, and the angle encoder is arranged on the rotating joint of the robotic arm.

[0127] ③The connection circuits of all components of the valve-controlled cylinder are completed through hydraulic oil pipes, and then integrated into the three-degree-of-freedom robotic arm to achieve one-arm-one-drive.

[0128] The simplified diagram of the overall structure of the multi-degree-of-freedom hydraulic mechanical arm driven by the hydraulic valve-controlled cylinder system and the components of the hydraulic valve-controlled cylinder system are shown in the figure below. Figure 2 , Figure 3 shown.

[0129] Reference Figure 4 , this embodiment may include the following solutions:

[0130] 1. First, this embodiment can perform dynamic modeling on the system of the three-degree-of-freedom hydraulic mechanical arm to obtain the expression relationship between the system input and output, and use the Lagrangian method to obtain the system equation:

[0131]

[0132] In the formula, θ=[θ 1 ,θ 2 θ3 ] T is the joint angle position; τ=[τ 1 ,τ 2 ,τ 3 ] T is the joint torque output by the hydraulic actuator; M is the joint space inertia force matrix; C is the coupling matrix of Coriolis force and centrifugal force; G is the gravity load; F f For friction.

[0133] 2. Each joint of the robot arm is driven by a hydraulic valve-controlled cylinder system. Specifically, the servo proportional valve can connect the rod and rodless chambers of the hydraulic cylinder through hydraulic pipes, and control the flow into the two chambers to control the reciprocating motion of the hydraulic cylinder. The valve-controlled cylinder system is constructed and the dynamic model of the hydraulic cylinder motion is obtained. The system output force is obtained as follows:

[0134]

[0135] In the formula, K hi is the hydraulic system gain coefficient, x vi is the servo valve spool displacement, ΔP i is the valve port pressure drop, B hi

[0136] is the hydraulic damping coefficient, f vi is the nonlinear friction force, is the actual joint angular velocity.

[0137] 3. Use the angle encoders arranged at each rotating joint to obtain the actual joint position θ i , the pressure sensor data arranged near the oil inlet and return port of the hydraulic cylinder is subtracted to obtain the valve port pressure drop ΔP i , the displacement sensor arranged inside the servo valve measures the displacement x of the servo valve core vi .

[0138] 4. Secondly, in order to facilitate the design of the super-helical synovial film controller in the future, it is necessary to obtain the system state space equation, so the state variables of the system are defined:

[0139]

[0140] The system model is rewritten as:

[0141]

[0142] 5. Finally, based on the above second-order system model, a super-helical sliding film controller is constructed, which can effectively suppress the chattering problem of traditional sliding film control without measuring the acceleration signal. The specific steps are as follows:

[0143] ST1: Synovial surface design.

[0144] Define the controller sliding membrane surface:

[0145] s=[s 1 ,s 2 ,s 3 ] T (5)

[0146] And the linear combination of tracking errors is expressed as follows:

[0147]

[0148] e i =θ i -θ i,d (7)

[0149] In the formula, i=[1,2,3]; θ i,d is the desired angle of the joint; e i is the joint angle error; i >0 is the sliding film surface slope parameter, which determines the error convergence speed.

[0150] ST2: Control law design:

[0151] According to the hydraulic manipulator dynamics model of formula (1), the controller input is decomposed into equivalent control terms and superhelical compensation terms:

[0152] τ=τ eq +τ sts (8)

[0153] In the formula, τ eq is an equivalent control term used to offset the nominal dynamics; τ sts is the super-helical compensation term, which is used to compensate for model uncertainty and hydraulic system disturbance:

[0154]

[0155] Where α=diag(α 1 ,α 2 ,α 3 ), β=diag(β 1 ,β 2 ,β 3 ) is the gain coefficient of the superhelical sliding film controller.

[0156] 6. In order to facilitate the actual implementation of the controller, define the extended state variable z i =∫sign(s i )dt, rewrite the above control law as follows:

[0157]

[0158] 7. In summary, the block diagram of the closed-loop control system of the three-degree-of-freedom hydraulic manipulator based on the super-helical synovial membrane of this embodiment is as follows: Figure 5 shown.

[0159] 8. At the same time, since each sensor has its own clock source and different sampling frequency, and a certain delay will be generated in the process of data preprocessing, transmission, and calculation of each device, in order to ensure the consistency of the state time of the actual system in the control algorithm, all the above-mentioned sensors must be synchronized in hardware through the unified clock source PTP protocol.

[0160] The technical solution of this embodiment is based on the collaborative design of super-spiral sliding mode control (STSMC) and sliding mode observer (SMO). It can bring inevitable application value for the strong nonlinearity, multiple disturbances and high coupling characteristics of the hydraulic manipulator: for industrial scenarios, it is suitable for hydraulic drive scenarios such as mining machinery and heavy-load handling robots that require high anti-disturbance and low jitter; for precision operations, it can be used for tasks that require strict trajectory accuracy, such as aerospace assembly and nuclear facility maintenance; for cost-sensitive fields: it reduces system costs by reducing the number of sensors, and is suitable for upgrading small and medium-sized hydraulic equipment.

[0161] The above technical solution can directly produce the following beneficial effects:

[0162] I. Significantly suppress control chattering: Through the high-order sliding mode characteristics of the superhelical algorithm, the sign function switching term of the traditional sliding mode control is converted into a continuous integral compensation, the chattering amplitude of the control input is reduced, the mechanical wear of the hydraulic actuator (such as servo valve, hydraulic cylinder) is reduced, and the service life is extended. At the same time, the excitation of the unmodeled high-frequency dynamics of the system is avoided, and the closed-loop stability is improved.

[0163] II. Reduce hardware cost and complexity: The integrated sliding mode observer (SMO) only requires joint position sensors to estimate angular velocity in real time. The velocity estimation error is less than 0.5 rad / s, which reduces the reliance on high-cost speed measuring devices, reduces hardware costs, and suppresses observation noise through saturation functions, thereby improving the reliability of the system in oil pollution and vibration scenarios.

[0164] Reference Figure 6 The embodiment of the present application also provides a trajectory tracking robust control system for a three-degree-of-freedom hydraulic mechanical arm, which can implement the above-mentioned trajectory tracking robust control method for a three-degree-of-freedom hydraulic mechanical arm. The control system includes:

[0165] A dynamic modeling module, used to construct a dynamic model for a three-degree-of-freedom hydraulic mechanical arm; wherein the three-degree-of-freedom hydraulic mechanical arm is driven by a hydraulic valve-controlled cylinder system;

[0166] A second-order modeling module, used to model the hydraulic actuator according to the dynamic model and the output force model of the hydraulic valve-controlled cylinder system to obtain a second-order model;

[0167] A controller design module, used for designing a super spiral synovial controller for the second-order model;

[0168] an error determination module for determining an error angle between a desired joint angle and an actual joint angle of a joint in the three-degree-of-freedom hydraulic mechanical arm;

[0169] A control amount determination module, used for inputting the error angle into the super spiral synovial controller to obtain a control amount;

[0170] A drive control module is used to control the movement of the hydraulic valve-controlled cylinder system according to the control quantity, system uncertainty parameters and external disturbance parameters, and then drive the hydraulic actuator to move the three-degree-of-freedom hydraulic mechanical arm.

[0171] It can be understood that the contents of the above method embodiments are all applicable to the present system embodiments, the functions specifically implemented by the present system embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0172] The embodiment of the present application also provides an electronic device, the electronic device includes a memory and a processor, the memory stores a computer program, and the processor implements the method of the embodiment of the present application when executing the computer program. The electronic device can be any intelligent terminal including a tablet computer, a car computer, etc.

[0173] It can be understood that the contents of the above method embodiments are all applicable to the embodiments of the present device, the functions specifically implemented by the embodiments of the present device are the same as those of the method of the present application, and the beneficial effects achieved are also the same as those achieved by the method of the present application.

[0174] See also Figure 7 , Figure 7 The hardware structure of an electronic device of another embodiment is illustrated, and the electronic device includes:

[0175] The processor 701 may be implemented by a general-purpose CPU (Central Processing Unit), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of the present application;

[0176] The memory 702 may be implemented in the form of a read-only memory (ROM), a static storage device, a dynamic storage device, or a random access memory (RAM). The memory 702 may store an operating system and other application programs. When the technical solutions provided in the embodiments of this specification are implemented by software or firmware, the relevant program codes are stored in the memory 702, and the processor 701 calls and executes the methods of the embodiments of this application.

[0177] Input / output interface 703, used to implement information input and output;

[0178] Communication interface 704, used to realize communication interaction between the device and other devices, which can be realized through wired mode (such as USB, network cable, etc.) or wireless mode (such as mobile network, WIFI, Bluetooth, etc.);

[0179] A bus 705 that transmits information between the various components of the device (e.g., the processor 701, the memory 702, the input / output interface 703, and the communication interface 704);

[0180] The processor 701 , the memory 702 , the input / output interface 703 and the communication interface 704 are connected to each other in communication within the device via a bus 705 .

[0181] An embodiment of the present application further provides a computer-readable storage medium, which stores a computer program, and the computer program implements the method of the present application when executed by a processor.

[0182] It can be understood that the contents of the above method embodiments are all applicable to the present storage medium embodiments, the functions specifically implemented by the present storage medium embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0183] The memory, as a non-transient computer-readable storage medium, can be used to store non-transient software programs and non-transient computer executable programs. In addition, the memory may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some embodiments, the memory may optionally include a memory remotely disposed relative to the processor, and these remote memories may be connected to the processor via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0184] The embodiments described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. Those skilled in the art will appreciate that with the evolution of technology and the emergence of new application scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0185] Those skilled in the art will appreciate that the technical solutions shown in the figures do not constitute a limitation on the embodiments of the present application, and may include more or fewer steps than shown in the figures, or a combination of certain steps, or different steps.

[0186] The system embodiment described above is merely illustrative, wherein the modules described as separate components may or may not be physically separated, i.e., may be located in one place, or may be distributed on multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment.

[0187] Those skilled in the art will appreciate that all or some of the steps in the methods disclosed above, and the functional modules / units in the systems and devices may be implemented as software, firmware, hardware, or a suitable combination thereof.

[0188] The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or modules is not necessarily limited to those steps or modules clearly listed, but may include other steps or modules that are not clearly listed or inherent to these processes, methods, products or devices.

[0189] It should be understood that in the present application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0190] In the several embodiments provided in the present application, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the system embodiments described above are only schematic. For example, the division of the above modules is only a logical function division. There may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of systems or modules, which can be electrical, mechanical or other forms.

[0191] The modules described above as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed on multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0192] In addition, each functional module in each embodiment of the present application can be integrated into a processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The above integrated modules can be implemented in the form of hardware or software functional modules.

[0193] If the integrated module is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including multiple instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, referred to as ROM), random access memory (Random Access Memory, referred to as RAM), disk or optical disk and other media that can store programs.

[0194] The preferred embodiments of the present invention are described above with reference to the accompanying drawings, but the scope of the rights of the present invention is not limited thereto. Any modification, equivalent substitution and improvement made by a person skilled in the art without departing from the scope and essence of the present invention should be within the scope of the rights of the present invention.

Claims

1. A trajectory tracking robust control method for a three-degree-of-freedom hydraulic manipulator, characterized in that: The method comprises the following steps: Constructing a dynamic model for a three-degree-of-freedom hydraulic mechanical arm; wherein the three-degree-of-freedom hydraulic mechanical arm is driven by a hydraulic valve-controlled cylinder system; Modeling the hydraulic actuator according to the dynamic model and using the output force model of the hydraulic valve-controlled cylinder system to obtain a second-order model; Designing a super-helical synovial controller for the second-order model; determining an error angle between a desired joint angle and an actual joint angle of a joint in the three-degree-of-freedom hydraulic robotic arm; Inputting the error angle into the super spiral synovial controller to obtain a control amount; The movement of the hydraulic valve-controlled cylinder system is controlled according to the control quantity, system uncertainty parameters and external disturbance parameters, thereby driving the hydraulic actuator to move the three-degree-of-freedom hydraulic mechanical arm.

2. The trajectory tracking robust control method of a three-degree-of-freedom hydraulic manipulator according to claim 1 is characterized in that: The method of constructing a dynamic model for a three-degree-of-freedom hydraulic mechanical arm comprises the following steps: The dynamic model of the three-degree-of-freedom hydraulic manipulator is constructed using the Lagrangian method: Where θ=[θ1,θ2θ3] T is the joint angle; τ=[τ1,τ2,τ3] T is the joint torque output by the hydraulic actuator; M is the joint space inertia force matrix; C is the Coriolis force and centrifugal force coupling matrix; G is the gravity load; F f is the friction of the system.

3. The trajectory tracking robust control method of a three-degree-of-freedom hydraulic manipulator according to claim 1 is characterized in that: The method of modeling the hydraulic actuator according to the dynamic model and using the output force model of the hydraulic valve-controlled cylinder system to obtain a second-order model includes the following steps: The actual joint angle is obtained by using angle encoders arranged at each rotating joint of the three-degree-of-freedom hydraulic mechanical arm; the hydraulic pressure is respectively obtained by using pressure sensors arranged at the oil inlet and oil return ports of the hydraulic cylinder and the pressure drop at the valve port is obtained by difference; the displacement of the servo valve core is measured by using a displacement sensor arranged inside the servo valve; The output force model of the hydraulic valve-controlled cylinder system is constructed as follows: Among them, K hi is the gain coefficient of the hydraulic valve-controlled cylinder system, x vi is the servo valve core displacement, ΔP i is the valve port pressure drop, B hi is the hydraulic damping coefficient, f vi is the nonlinear friction force; is the actual joint angular velocity; Defining the state variables of the system and then constructing the second-order model according to the dynamic model; The state variables are: The second-order model is:

4. The trajectory tracking robust control method of a three-degree-of-freedom hydraulic manipulator according to claim 1, characterized in that: The method of designing a super spiral synovial controller for the second-order model comprises the following steps: The synovial surface of the superhelical synovial controller is defined as: <h2 style=";text-align:left;direction:ltr">s = [s1,s2,s3]<h2 style=";text-align:left;direction:ltr"> T <h2 style=";text-align:left;direction:ltr"> ; The sliding surface is expressed as a linear combination of tracking errors: e i =θ i -θ i,d ; Among them, i=[1,2,3]; θ i,d is the expected joint angle; e i is the error joint angle; i >0 is the sliding film surface slope parameter, which is used to determine the error convergence speed; The input of the superhelical synovial controller is defined to include an equivalent control term and a superhelical compensation term; τ=τ eq +t sts ; Where, τ represents the input of the superhelical synovial controller, τ eq is the equivalent control term used to offset the nominal dynamics; τ sts is the superhelix compensation term, used to compensate for the system uncertainty parameter and the external disturbance parameter; Wherein, α=diag(α1,α2,α3), β=diag(β1,β2,β3) are the gain coefficients of the super-helical sliding film controller; Define the extended state variable as: z i =∫sign(s i )dt; Then the control law of the super spiral sliding film controller is obtained as follows:

5. The trajectory tracking robust control method of a three-degree-of-freedom hydraulic manipulator according to claim 1, characterized in that: Determining the error angle between the expected joint angle and the actual joint angle of the joint in the three-degree-of-freedom hydraulic mechanical arm comprises the following steps: Obtaining the expected joint angle; Obtaining the actual joint angle through an angle encoder; The expected joint angle is subtracted from the actual joint angle to obtain the error angle.

6. The trajectory tracking robust control method of a three-degree-of-freedom hydraulic manipulator according to claim 1, characterized in that: The step of inputting the error angle into the super spiral synovial controller to obtain a control amount comprises the following steps: Determining the joint velocity corresponding to the actual joint angle by a synovial membrane observer; The error angle and the joint speed are input into the super spiral synovial controller to obtain the control amount.

7. A trajectory tracking robust control method for a three-degree-of-freedom hydraulic manipulator according to any one of claims 1 to 6, characterized in that: The method further comprises the following steps: All sensors in the three-degree-of-freedom hydraulic mechanical arm are synchronized in hardware through a unified clock source PTP protocol.

8. A trajectory tracking robust control system for a three-degree-of-freedom hydraulic manipulator, characterized in that: The control system comprises: A dynamic modeling module, used to construct a dynamic model for a three-degree-of-freedom hydraulic mechanical arm; wherein the three-degree-of-freedom hydraulic mechanical arm is driven by a hydraulic valve-controlled cylinder system; A second-order modeling module, used to model the hydraulic actuator according to the dynamic model and the output force model of the hydraulic valve-controlled cylinder system to obtain a second-order model; A controller design module, used for designing a super spiral synovial controller for the second-order model; an error determination module for determining an error angle between a desired joint angle and an actual joint angle of a joint in the three-degree-of-freedom hydraulic mechanical arm; A control amount determination module, used for inputting the error angle into the super spiral synovial controller to obtain a control amount; A drive control module is used to control the movement of the hydraulic valve-controlled cylinder system according to the control quantity, system uncertainty parameters and external disturbance parameters, and then drive the hydraulic actuator to move the three-degree-of-freedom hydraulic mechanical arm.

9. An electronic device, characterized in that: The electronic device comprises a memory and a processor, the memory stores a computer program, and the processor implements the method according to any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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