Servo Control Method and System for Multi-Joint Hydraulic Robotic Arm Based on Slipform Adaptation

Abstract

This invention proposes a servo control method and system for a multi-joint hydraulic manipulator based on sliding mode adaptation, relating to the field of hydraulic equipment servo control technology. Based on the manipulator's current pose and received command information, the method generates the end effector trajectory within the workspace and calculates the desired angular displacement, angular velocity, and angular acceleration of each joint. It then obtains the actual angular displacement of each joint under the current pose and calculates the actual angular velocity. Based on the desired angular displacement, angular velocity, and angular acceleration, and the actual angular displacement, angular velocity, and angular acceleration, combined with the manipulator's dynamics model, the method calculates the driving force of each joint. Based on the desired angular displacement, actual angular displacement, and driving force of each joint, a sliding mode surface is constructed, the adaptive rate is updated, and sliding mode adaptive control is performed on the manipulator. This invention enables precise position control of multi-axis hydraulic actuators with positional characteristics, achieving coordinated control of complex motion laws between multiple axes.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic equipment servo control technology, and particularly relates to a servo control method and system for multi-joint hydraulic robotic arms based on slid adaptive control. 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] With the rapid development of electronic technology, computer technology, automatic control technology, and precision machining technology, the research and development and production technology of motor-driven industrial robots, from servo motors, multi-axis controllers, reducers, sensors to system integration, has become very mature, reaching the level of mass production and installation. They are widely used in industrial production scenarios such as automated welding, handling, loading and unloading, assembly, grinding, and spraying. The installed capacity of industrial robots has become an important indicator for measuring the level of industrial automation in a country.

[0004] Although motor-driven industrial robots are technologically mature, offer high motion precision, and are low-cost, leading to their widespread application in industrial production, their low power-to-weight ratio and the difficulty in providing high-level protection for electrical components, such as waterproofing, explosion-proofing, dustproofing, and electromagnetic interference resistance, prevent their application in harsh working environments such as high-altitude power grid operations, equipment maintenance and waste disposal in nuclear radiation environments, underwater equipment installation and exploration in the ocean, and underground spraying and material handling in coal mines. In contrast, hydraulic robotic arms offer higher power density and stronger protective performance. They can be designed with high levels of protection, including waterproofing, radiation protection, and explosion-proofing, to meet the specific needs of the working environment. This allows them to replace or assist humans in harsh working conditions, demonstrating significant research value and broad application prospects.

[0005] Currently, there are no mass-produced and applied multi-joint hydraulic robotic arms in China; they are still in the experimental prototype stage, developed for specific application scenarios. Each joint of the robotic arm uses an independent PID servo control method, and at the operational level, it mainly employs master-slave remote operation or kinematics-based motion control methods. These control methods not only have poor control accuracy but are also prone to oscillation or crawling. Furthermore, there are no multi-axis hydraulic servo controller products specifically designed for use with multi-joint hydraulic robotic arms. Therefore, existing multi-joint hydraulic robotic arm control technology severely restricts the development of automation and unmanned operation in dangerous and harsh environments such as underwater, nuclear radiation, and flammable and explosive environments. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this invention provides a servo control method and system for a multi-joint hydraulic robotic arm based on sliding diaphragm adaptive control. It considers the characteristic variables after linearization of the actual servo output model of the hydraulic drive system: driving force and hydraulic cylinder length change rate. Both characteristic variables are adaptively controlled, and the robustness of sliding diaphragm control is combined to eliminate the influence of nonlinear factors such as servo valve hysteresis, leakage, zero drift and hydraulic cylinder friction, so as to achieve coordinated control of complex motion laws between multiple axes.

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

[0008] The first aspect of this invention provides a servo control method for a multi-joint hydraulic robotic arm based on synovial adaptive control.

[0009] A servo control method for a multi-joint hydraulic robotic arm based on slippery membrane adaptive control includes:

[0010] Based on the current pose of the robotic arm and the received command information, the motion trajectory of the robotic arm end effector in the workspace is generated, and the expected angular displacement, angular velocity and angular acceleration of each joint are solved.

[0011] Obtain the actual angular displacement of each joint of the robotic arm in its current pose, and calculate the actual angular velocity of each joint in its current pose;

[0012] Based on the expected angular displacement, angular velocity, and angular acceleration of each joint, and the actual angular displacement and angular velocity of each joint under the current pose, combined with the dynamic model of the robotic arm, the driving force required for each joint to control is calculated.

[0013] Based on the expected angular displacement, actual angular displacement, and driving force of each joint, a sliding surface is constructed. The adaptive rate is updated according to the driving force of each joint and the rate of change of hydraulic cylinder length required for control, and the robotic arm is subjected to sliding adaptive control.

[0014] Furthermore, using preset point-to-point, circular arc, electronic gear, or polynomial trajectory planning programs, the end effector motion trajectory of the robotic arm within the workspace can be generated.

[0015] Furthermore, the specific steps for solving for the desired angular displacement, angular velocity, and angular acceleration of each joint are as follows:

[0016] Based on the kinematic model of the robotic arm, the end effector motion trajectory in the workspace is mapped to the angular displacement curves of each joint of the robotic arm in the joint space.

[0017] In the angular displacement curves of each joint of the robotic arm within the joint space, after smoothing using a trajectory planning method based on fifth-order polynomial interpolation, the expected angular displacement, angular velocity, and angular acceleration of each joint are calculated.

[0018] Furthermore, the calculation of the actual angular velocity of each joint in the current pose specifically involves using a third-order integrator chain differentiator to calculate the actual angular velocity of each joint.

[0019] Furthermore, the driving forces required for each joint in the calculation control are specifically as follows:

[0020] Based on the desired angular acceleration and the current pose of the robotic arm, the joint torque is obtained. Combining the mapping relationship between the hydraulic cylinder output force and the joint torque, the driving force of each joint is calculated, including the output force of the linear hydraulic cylinder and the output torque of the swing hydraulic cylinder.

[0021] Furthermore, the synovial surface specifically comprises:

[0022] s = e = q d -q

[0023] Where, q d Let e ​​represent the desired joint angular displacement, q represent the current joint angular displacement, and e = q. d -q represents the angular displacement error of the joint.

[0024] Furthermore, the formula for the adaptive rate is:

[0025]

[0026] in, f is the rate of change of the hydraulic cylinder length. c To control the required driving force, s is the sliding surface. This is an estimate of the system parameter 'a' that is continuously updated using an adaptive rate. Let γ be the estimated value of the system parameter b, which is continuously updated using the adaptive rate, and let γ be the adaptive control parameter matrix.

[0027] Furthermore, the servo control signal is a servo control voltage signal, which is converted into a current signal and fed to the servo valve to control the movement of the robotic arm;

[0028] The specific formula for the servo control voltage signal is as follows:

[0029]

[0030] Where u is the servo control voltage signal. This is an estimate of the system parameter 'a' that is continuously updated using an adaptive rate. Let be the rate of change of the desired linear displacement obtained from the desired trajectory. f is an estimate of the system parameter b that is continuously updated using the adaptive rate. c To control the required driving force of each joint, k is the exponential approach control parameter, η is the constant velocity approach control parameter, and s is the synovial surface.

[0031] The second aspect of the present invention provides a servo control system for a multi-joint hydraulic robotic arm based on synovial adaptive servo control.

[0032] The servo control system for a multi-joint hydraulic robotic arm based on gliding adaptation includes a first calculation module, a second calculation module, a third calculation module, and an adaptive control module.

[0033] The first calculation module is configured to generate the end effector trajectory of the robotic arm in the workspace based on the current pose of the robotic arm and the received instruction information, and to solve for the expected angular displacement, angular velocity and angular acceleration of each joint.

[0034] The second calculation module is configured to: obtain the actual angular displacement of each joint under the current pose of the robotic arm, and calculate the actual angular velocity of each joint under the current pose;

[0035] The third calculation module is configured to: calculate the driving force required for each joint for control based on the expected angular displacement, angular velocity, and angular acceleration of each joint and the actual angular displacement, angular velocity, and angular acceleration of each joint under the current pose, combined with the dynamic model of the robotic arm;

[0036] The adaptive control module is configured to: construct a sliding surface based on the desired angular displacement, actual angular displacement and driving force of each joint, and update the adaptive rate according to the driving force of each joint and the change rate of hydraulic cylinder length required for control, so as to perform sliding adaptive control on the robotic arm.

[0037] A third aspect of the present invention provides a servo control device for a multi-joint hydraulic robotic arm based on synovial adaptive servo control.

[0038] A servo control device for a multi-joint hydraulic robotic arm based on sliding diaphragm adaptive control includes a core controller, an encoder signal acquisition module, an analog output module, and a voltage-to-current conversion module.

[0039] The core controller receives instructions from the user or host computer, runs the servo control method, and outputs servo control signals;

[0040] The encoder signal acquisition module performs kinematic calculations on the joint angles of each joint to obtain the current pose of the robotic arm, and then transmits it to the core controller.

[0041] The analog output module is connected to the core controller and converts the servo control signal into an adjustable continuous voltage signal through digital-to-analog conversion.

[0042] The voltage-to-current conversion module converts the voltage signal output by the analog output module into a current control signal for the electro-hydraulic servo valve. The electro-hydraulic servo valve controls the flow of hydraulic oil into and out of the hydraulic cylinder based on the received current signal, thereby controlling the movement of each joint of the robotic arm.

[0043] The servo control method is the servo control method for a multi-joint hydraulic robotic arm based on gliding adaptation provided in the first aspect of the present invention.

[0044] The above one or more technical solutions have the following beneficial effects:

[0045] When performing adaptive sliding diaphragm control, this invention considers the characteristic variables of the actual servo output model of the hydraulic drive system after linearization: driving force and hydraulic cylinder length change rate. Both characteristic variables are adaptively controlled, and the robustness of sliding diaphragm control is combined to eliminate the influence of nonlinear factors such as servo valve hysteresis, leakage, zero drift and hydraulic cylinder friction. In other words, this invention performs precise position control on multi-axis hydraulic actuators and realizes coordinated control of complex motion laws between multiple axes.

[0046] This invention provides operators with a user-friendly interactive mode by connecting to a host computer, multi-axis serial / parallel master hand, multi-axis joystick, touch screen and other diverse command input devices through various communication methods, thereby reducing operator fatigue caused by long-term monotonous operation.

[0047] This invention incorporates a typical kinematic model of a multi-axis serial robotic arm, which can automatically map from the operating space to the joint space, reducing the difficulty of motion planning for multi-axis hydraulic robotic arms.

[0048] This invention incorporates point-to-point, circular arc, electronic gear, and polynomial trajectory motion planning and control functions, and can directly generate motion control programs through command input.

[0049] 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

[0050] 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.

[0051] Figure 1 This is a flowchart of the method in the first embodiment.

[0052] Figure 2 The flowchart shows the control algorithm for the first embodiment.

[0053] Figure 3 This is a schematic diagram of the servo algorithm for the first embodiment of a multi-joint hydraulic robotic arm.

[0054] Figure 4 This is a structural diagram of the device according to the third embodiment. Detailed Implementation

[0055] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0056] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0057] Example 1

[0058] In one or more embodiments, a servo control method for a multi-joint hydraulic robotic arm based on sluice film adaptation is disclosed, such as... Figure 1 As shown, it includes the following steps:

[0059] Step S1: Based on the current pose of the robotic arm and the received instruction information, generate the motion trajectory of the robotic arm end effector in the workspace, and solve for the expected angular displacement, angular velocity and angular acceleration of each joint;

[0060] Step S2: Obtain the actual angular displacement of each joint in the current pose of the robotic arm, and calculate the actual angular velocity of each joint in the current pose;

[0061] Step S3: Based on the expected angular displacement, angular velocity, and angular acceleration of each joint, and the actual angular displacement and angular velocity of each joint under the current pose, and combined with the robotic arm dynamics model, calculate the driving force required for each joint for control.

[0062] Step S4: Based on the expected angular displacement, actual angular displacement and driving force of each joint, construct the sliding surface, update the adaptive rate according to the driving force of each joint and the change rate of hydraulic cylinder length required for control, and perform sliding adaptive control on the robotic arm.

[0063] The implementation process of the servo control method for a multi-joint hydraulic robotic arm based on synovial adaptive control in this embodiment will be described in detail below.

[0064] Multi-joint hydraulic robotic arms are mostly serial topologies and can be in different forms such as 4-axis, 5-axis, and 6-axis. This embodiment can be applied to the control of various multi-joint hydraulic robotic arms by setting the topology and parameters of the robotic arm.

[0065] The following is in conjunction with the appendix Figure 2 The given control algorithm flowchart provides a detailed description of the specific implementation of the servo control method for a multi-joint hydraulic robotic arm:

[0066] The hydraulic robotic arm servo controller is activated, automatically executing a self-test program to identify external connected devices, load the robot kinematics model built into the controller, and initialize the robotic arm's kinematic and dynamic parameters.

[0067] After the self-test is passed, the external hydraulic station of the robotic arm is turned on to supply high-pressure hydraulic oil to the robotic arm. The controller detects whether the hydraulic oil pressure and temperature in the hydraulic robotic arm oil circuit are within the normal working range to prevent damage to hydraulic seals, pipelines or actuators due to excessive hydraulic oil pressure and temperature. Insufficient pressure will affect the working performance of the robotic arm. If the hydraulic oil pressure and temperature are abnormal, the controller will issue an alarm message; otherwise, it will enter the standby mode to receive operation commands.

[0068] When the controller receives a command from an external host computer, remote control master hand, multi-axis joystick or touch screen, it first determines whether it is a stop command. If it is a stop command, it resets the robotic arm to the long-term stop position and stops running the control program. If it is not a stop command, it reads the current position information of the robotic arm end effector in the workspace through the encoder signal acquisition module.

[0069] The controller automatically determines whether the given work position or trajectory is entirely within the workspace of the robotic arm. If so, it generates the desired end trajectory based on the current posture of the robotic arm and the received instruction information, using preset point-to-point, circular arc, electronic gear, or polynomial trajectory planning programs within the controller. When the given work position or trajectory is outside the workspace, the controller issues an alarm. The operator can specify several key points in the original instruction through the human-machine interface, and the controller will regenerate a trajectory within the workspace that is closest to the target trajectory.

[0070] After completing the end-effector trajectory planning, the controller first maps the end-effector trajectory in the workspace to the angular displacement curves of each joint in the joint space based on the kinematic model, and selects several path points in the curves, and associates the path points with time.

[0071] To ensure the smoothness of the robotic arm's operation, the angular velocity and angular acceleration trajectories of each joint should be smooth and uninterrupted. Furthermore, in order to eliminate the impact caused by the sudden changes in control signals when the robotic arm starts and stops, it is necessary to constrain the angular velocity and angular acceleration at the initial and stopping moments of the trajectory.

[0072] Therefore, a trajectory planning method using quintic polynomial interpolation is employed to smooth the trajectory within the joint space. The mathematical expression of the quintic polynomial is as follows:

[0073]

[0074] Wherein, θ(t), and These represent the interpolated joint displacement, velocity, and acceleration variables, respectively; t is the time variable; and a0...a5 are undetermined coefficients.

[0075] After adding constraints to the angular velocities and angular accelerations at the start and end points, the initial time t0 = 0 and the cutoff time t are obtained. f The solution for the fifth-order polynomial interpolation is:

[0076]

[0077] Wherein, θ0, and Let t represent the desired initial joint displacement, velocity, and acceleration, respectively. f θ is the deadline. f , and These represent the joint displacement, velocity, and acceleration at the desired cutoff time, respectively.

[0078] By combining the trajectories of all intermediate start and end points, the desired trajectories of the robotic arm's joints can be obtained.

[0079] Based on the inverse dynamics model of the robotic arm, the current pose information, and the desired trajectory, the expected driving force / torque of each joint is calculated. The actual driving force / torque of the joint can be indirectly calculated by reading the pressure of the two chambers of the hydraulic cylinder through the analog input module, or by reading the multi-dimensional force sensor data at the end of the robotic arm through the analog input module, and further calculating the end load through the robotic arm dynamics model, and feeding it back to the teleoperator, providing the operator with a certain proportion of force feedback, and reducing the operator's fatigue during long-term operation.

[0080] like Figure 3 As shown, after obtaining the desired angular displacement and feedback angular displacement of each joint, a third-order integrator chain differentiator is used to calculate the feedback angular velocity and angular acceleration of each joint. The continuous-time state-space equation of the third-order integrator chain differentiator is:

[0081]

[0082] Where a1, b1, and c1 are a set of constants, ε is a constant related to the system response characteristics, and θ is the raw data read by the control system from the sensor; when b1×c1>a1, according to the Hurwitz stability criterion, the system is asymptotically stable, where the smaller ε is, the faster the system response. x1, x2, and x3 are the state variables in the state-space equation. When the system is asymptotically stable, x1→θ, and the values ​​of joint angular velocity and angular acceleration can be approximated by x2 and x3.

[0083] Real-time control systems cannot achieve continuous-time chain differentiation, but the continuous-time state-space equations can be discretized using the bilinear transformation method. The specific form of this method is as follows:

[0084]

[0085]

[0086]

[0087]

[0088] Where T is the time constant in seconds, I is the identity matrix, and A, B, C, and D are the system matrix, control matrix, output matrix, and direct transfer matrix of the continuous-time state-space equations, respectively. d B d C d and D d These are the discretized system matrix, control matrix, output matrix, and direct transfer matrix.

[0089] Due to the lack of precise servo valve and hydraulic cylinder model parameters, it is first necessary to obtain rough estimates of the model parameters through experiments in engineering. These rough estimates can be determined by observing the motion of the open-loop system. During the extension and retraction of the hydraulic cylinder, a control signal is directly given, and the motion of the hydraulic cylinder in different directions is observed. The joint force values ​​and the rate of change of the hydraulic cylinder length are recorded. Based on the servo valve control current i... v With cylinder speed Hydraulic cylinder output force f c To determine the linear relationship between them, the least squares method is used to determine a rough range of parameter values.

[0090] After obtaining the approximate range of servo valve model parameters, an adaptive sliding diaphragm control algorithm combining torque calculation is used for servo control; the designed sliding diaphragm surface is as follows:

[0091] s = e = q d -q

[0092] Where, q d Let e ​​represent the desired joint angular displacement, q represent the current joint angular displacement, and e = q. d -q represents the position tracking error, i.e., the angular displacement error.

[0093] The linearized model of the hydraulic cylinder is simplified to: Δ represents the modeling error. For linear hydraulic cylinders... For the rate of change of linear displacement, f c For the output force; for the swing cylinder For the rate of change of angular displacement, f c Let be the joint torque, and a and b be the linearized model parameters; take Let a be an estimate. Given an estimate of b, the adaptive rate is designed as follows:

[0094]

[0095] in, f is the rate of change of the hydraulic cylinder length. c The driving force is s, where s is the sliding surface. This is an estimate of the system parameter 'a' that is continuously updated using an adaptive rate. Let γ be the estimated value of the system parameter b, which is continuously updated using the adaptive rate, and let γ be the adaptive control parameter matrix. During the control process, the control system is continuously adjusted according to the adaptive rate.

[0096] To make the designed sliding surface s→0, the sliding control algorithm uses an exponential approach law. Let k be the exponentially approaching control parameter and η be the constant velocity approaching control parameter. Then, the adaptive sliding diaphragm control law is designed as follows:

[0097]

[0098] Where u is the servo control voltage signal. This is an estimate of the system parameter 'a' that is continuously updated using an adaptive rate. The desired linear displacement change rate is obtained from the desired trajectory (for the swing cylinder, it is the desired angular velocity). f is an estimate of the system parameter b that is continuously updated using the adaptive rate. c To control the required driving force of each joint, k is the exponential approach control parameter, η is the constant velocity approach control parameter, and s is the synovial surface.

[0099] The above index is approaching the middle. The term ensures that the approach velocity gradually decreases from a large value to zero, which not only shortens the approach time but also makes the velocity of the moving point when it reaches the sliding surface very small. However, in simple exponential approach, the moving point approaches the switching surface a gradual process and cannot guarantee reaching it within a finite time. Therefore, there is no sliding mode on the switching surface. So, a constant velocity approach term needs to be added. By ensuring that the approach velocity is η instead of zero when s approaches zero, we can guarantee arrival in a finite time.

[0100] In the servo operation of a hydraulic robotic arm, in order to ensure rapid approach while reducing chattering, k should be increased while η is decreased.

[0101] To eliminate the coupling between the components of a hydraulic robotic arm, control requires the use of a calculated torque method. This is based on a known robotic arm dynamics model. In the case of a given control law f c The value of f for the swing cylinder. cThis is the joint torque τ. However, for linear cylinders, the mapping relationship between the hydraulic cylinder output force and the joint torque needs to be considered. The magnitude of the torque τ is equal to the force multiplied by its effective working length. Let the output force of the hydraulic actuator be f. ci The effective length is denoted as l. ei Then the joint torque τ i for:

[0102] τ i =f ci l ei =f ci l i2 sin(q i )

[0103]

[0104] Among them, l i1 and l i2 Let l be the structural constant of the robotic arm. ki It is a variable related to the joint angular displacement q, and the subscripts i = 2, 3, 5 correspond to three rotary joints using linear cylinders.

[0105] The desired angular acceleration and the current pose of the robotic arm are calculated based on the trajectory to obtain the joint torque. Based on the mapping relationship between the hydraulic cylinder output force and the joint torque, the output force of the linear hydraulic cylinder and the output torque of the oscillating hydraulic cylinder are calculated respectively. Let q and q represent the joint angular acceleration vectors of a given trajectory. This represents the angular displacement and angular velocity vectors of the joints in the current pose of the robotic arm. Here is the mass matrix of the robotic arm. For centrifugal force and Coriolis force vectors, This is the gravity vector.

[0106] When the current motion trajectory is completed, the robotic arm stops in the current pose and waits for new instructions until it receives a new motion instruction or a stop instruction.

[0107] Example 2

[0108] In one or more embodiments, a servo control system for a multi-joint hydraulic robotic arm based on sluice film adaptation is disclosed, including a first calculation module, a second calculation module, a third calculation module, and an adaptive control module:

[0109] The first calculation module is configured to generate the end effector trajectory of the robotic arm in the workspace based on the current pose of the robotic arm and the received instruction information, and to solve for the expected angular displacement, angular velocity and angular acceleration of each joint.

[0110] The second calculation module is configured to: obtain the actual angular displacement of each joint under the current pose of the robotic arm, and calculate the actual angular velocity of each joint under the current pose;

[0111] The third calculation module is configured to: calculate the driving force required for each joint for control based on the expected angular displacement, angular velocity, and angular acceleration of each joint and the actual angular displacement, angular velocity, and angular acceleration of each joint under the current pose, combined with the dynamic model of the robotic arm;

[0112] The adaptive control module is configured to: construct a sliding surface based on the desired angular displacement, actual angular displacement and driving force of each joint, and update the adaptive rate according to the driving force of each joint and the change rate of hydraulic cylinder length required for control, so as to perform sliding adaptive control on the robotic arm.

[0113] Example 3

[0114] In one or more embodiments, a servo control device for a multi-joint hydraulic robotic arm based on synovial adaptive design is disclosed, such as... Figure 4 As shown, it includes a core controller, an encoder signal acquisition module, an analog input module, an analog output module, a voltage-to-current conversion module, and a human-machine interface device.

[0115] The core controller receives instructions from the user or host computer, runs the servo control method of Example 1, and outputs servo control signals based on feedback information. To facilitate user operation, the core controller has built-in point-to-point, circular arc, and polynomial trajectory encapsulation instruction programs, as well as electronic gear instruction programs for precise coupling motion of multiple joints. Users can quickly generate motion control programs through instruction and parameter input.

[0116] The encoder signal acquisition module converts the encoder signal and uses a high-speed conversion chip to convert the RS422 communication protocol signal from the encoder end into a TTL signal that can be read by the core controller. The encoder is used to acquire the joint angle of each joint. The encoder signal acquisition module performs kinematic calculations to obtain the current pose of the robotic arm and transmits it to the core controller.

[0117] The analog input module is used to acquire analog signals from the force sensor, oil temperature sensor, and pressure sensor on the robotic arm, and transmit them to the core controller through the internal analog-to-digital converter module.

[0118] The analog output module, connected to the core controller, converts the calculation results of the servo control method into an adjustable continuous voltage signal through digital-to-analog conversion.

[0119] The voltage-to-current conversion module converts the voltage signal output by the analog output module into a current control signal for the electro-hydraulic servo valve. The electro-hydraulic servo valve controls the flow of hydraulic oil into and out of the hydraulic cylinder based on the received current signal, thereby controlling the movement of each joint of the robotic arm.

[0120] Human-machine interaction devices commonly used in hydraulic robotic arm control systems include multi-axis serial / parallel master arms, multi-axis joysticks, touch screens, and host computers. These devices can be connected to the core controller through different hardware interfaces and data transmission protocols for inputting robotic arm control commands or master-slave control. Simultaneously, they can use sensors to feed back the status information of the robotic arm to the operator.

[0121] The host computer connects to the core controller via an Ethernet bus to achieve data interaction between the two. The core controller can be a high-performance NI board-type industrial computer, a box-type industrial control computer, or other high-performance embedded controller. The host computer sends various motion commands to the core controller through its UI interface and receives the data returned by the core controller. Its interface displays the hydraulic system pressure, temperature, and changes in various working states such as the displacement of the robotic arm joints, the end effector posture, and the load. It can also intuitively control the robotic arm.

[0122] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A servo control method for a multi-joint hydraulic robotic arm based on sliding diaphragm adaptation, characterized in that, include: Based on the current pose of the robotic arm and the received command information, the motion trajectory of the robotic arm end effector in the workspace is generated, and the expected angular displacement, angular velocity and angular acceleration of each joint are solved. Obtain the actual angular displacement of each joint of the robotic arm in its current pose, and calculate the actual angular velocity of each joint in its current pose; Based on the expected angular displacement, angular velocity, and angular acceleration of each joint, and the actual angular displacement and angular velocity of each joint under the current pose, combined with the dynamic model of the robotic arm, the driving force required for each joint to control is calculated. Based on the expected angular displacement, actual angular displacement and driving force of each joint, a sliding surface is constructed. According to the driving force of each joint and the rate of change of hydraulic cylinder length required for control, the adaptive rate is updated to perform sliding adaptive control on the robotic arm. The synovial adaptive control first calculates the angular displacement error of each joint based on the expected and actual angular displacements of each joint to obtain the synovial surface; then, according to the driving force of each joint and the change rate of the hydraulic cylinder length required for control, it updates the adaptive rate of the hydraulic cylinder model to obtain the servo control signal and control the movement of the robotic arm. The synovial surface is specifically: in, This represents the desired joint angular displacement. This indicates the current joint angular displacement. This indicates the angular displacement error of the joint; The formula for the adaptive rate is: in, The rate of change of the hydraulic cylinder length. As the driving force, For the synovial surface, System parameters that are continuously updated using adaptive rate The estimated value, System parameters that are continuously updated using adaptive rate The estimated value, This is the adaptive control parameter matrix; The servo control signal is a servo control voltage signal, which is converted into a current signal and sent to the servo valve to control the movement of the robotic arm. The specific formula for the servo control voltage signal is as follows: in, For servo control voltage signal, System parameters that are continuously updated using adaptive rate The estimated value, Let be the rate of change of the desired linear displacement obtained from the desired trajectory. System parameters that are continuously updated using adaptive rate The estimated value, To control the required driving force of each joint, For exponential approach control parameters, To achieve constant velocity approach control parameters, It is the synovial surface.

2. The servo control method for a multi-joint hydraulic robotic arm based on gliding adaptation as described in claim 1, characterized in that, Using preset point-to-point, circular arc, electronic gear, or polynomial trajectory planning programs, generate the end effector motion trajectory of the robotic arm within the workspace.

3. The servo control method for a multi-joint hydraulic robotic arm based on sliding diaphragm adaptation as described in claim 2, characterized in that, The specific steps for calculating the desired angular displacement, angular velocity, and angular acceleration of each joint are as follows: Based on the kinematic model of the robotic arm, the end effector motion trajectory in the workspace is mapped to the angular displacement curves of each joint of the robotic arm in the joint space. In the angular displacement curves of each joint of the robotic arm within the joint space, after smoothing using a trajectory planning method based on fifth-order polynomial interpolation, the expected angular displacement, angular velocity, and angular acceleration of each joint are calculated.

4. The servo control method for a multi-joint hydraulic robotic arm based on gliding adaptation as described in claim 1, characterized in that, The calculation of the actual angular velocity of each joint under the current pose is specifically performed by using a third-order integrator chain differentiator to calculate the actual angular velocity of each joint.

5. The servo control method for a multi-joint hydraulic robotic arm based on gliding adaptation as described in claim 1, characterized in that, The driving forces required for each joint in the calculation and control are specifically as follows: Based on the desired angular acceleration and the current pose of the robotic arm, the joint torque is obtained. Combining the mapping relationship between the hydraulic cylinder output force and the joint torque, the driving force of each joint is calculated, including the output force of the linear hydraulic cylinder and the output torque of the swing hydraulic cylinder.

6. A servo control system for a multi-joint hydraulic robotic arm based on gliding membrane adaptation, characterized in that, It includes a first calculation module, a second calculation module, a third calculation module, and an adaptive control module: The first calculation module is configured to generate the end effector trajectory of the robotic arm in the workspace based on the current pose of the robotic arm and the received instruction information, and to solve for the expected angular displacement, angular velocity and angular acceleration of each joint. The second calculation module is configured to: obtain the actual angular displacement of each joint under the current pose of the robotic arm, and calculate the actual angular velocity of each joint under the current pose; The third calculation module is configured to calculate the driving force required for each joint for control based on the expected angular displacement, angular velocity, and angular acceleration of each joint and the actual angular displacement and angular velocity of each joint under the current pose, combined with the dynamic model of the robotic arm. The adaptive control module is configured to: construct a sliding surface based on the desired angular displacement, actual angular displacement, and driving force of each joint; update the adaptive rate according to the driving force of each joint and the rate of change of the hydraulic cylinder length required for control; and perform sliding adaptive control on the robotic arm. The synovial adaptive control first calculates the angular displacement error of each joint based on the expected and actual angular displacements of each joint to obtain the synovial surface; then, according to the driving force of each joint and the change rate of the hydraulic cylinder length required for control, it updates the adaptive rate of the hydraulic cylinder model to obtain the servo control signal and control the movement of the robotic arm. The synovial surface is specifically: in, This represents the desired joint angular displacement. This indicates the current joint angular displacement. This indicates the angular displacement error of the joint; The formula for the adaptive rate is: in, The rate of change of the hydraulic cylinder length. As the driving force, For the synovial surface, System parameters that are continuously updated using adaptive rate The estimated value, System parameters that are continuously updated using adaptive rate The estimated value, This is the adaptive control parameter matrix; The servo control signal is a servo control voltage signal, which is converted into a current signal and sent to the servo valve to control the movement of the robotic arm. The specific formula for the servo control voltage signal is as follows: in, For servo control voltage signal, System parameters that are continuously updated using adaptive rate The estimated value, Let be the rate of change of the desired linear displacement obtained from the desired trajectory. System parameters that are continuously updated using adaptive rate The estimated value, To control the required driving force of each joint, For exponential approach control parameters, To achieve constant velocity approach control parameters, It is the synovial surface.

7. A servo control device for a multi-joint hydraulic robotic arm based on gliding membrane self-adaptation, characterized in that, It includes a core controller, an encoder signal acquisition module, an analog output module, and a voltage-to-current conversion module; The core controller receives instructions from the user or host computer, runs the servo control method, and outputs servo control signals; The encoder signal acquisition module performs kinematic calculations on the joint angles of each joint to obtain the current pose of the robotic arm, and then transmits it to the core controller. The analog output module is connected to the core controller and converts the servo control signal into an adjustable continuous voltage signal through digital-to-analog conversion. The voltage-to-current conversion module converts the voltage signal output by the analog output module into a current control signal for the electro-hydraulic servo valve. The electro-hydraulic servo valve controls the flow of hydraulic oil into and out of the hydraulic cylinder based on the received current signal, thereby controlling the movement of each joint of the robotic arm. The servo control method is the servo control method for a multi-joint hydraulic robotic arm based on synovial adaptive control as described in any one of claims 1-5.

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