A preset time convergent robot active anti-interference and control method and device

Abstract

The application belongs to the technical field of robot anti-interference, and discloses a preset time convergence robot active anti-interference and control method and device, which comprises the following steps: constructing an equivalent input interference state space model of a robot controlled system; constructing a preset time equivalent input interference estimator based on the equivalent input interference state space model; giving a reference input of the robot controlled system, obtaining a control signal after the reference input passes through a controller, taking the control signal as an input of the preset time equivalent input interference estimator, taking an output of the preset time equivalent input interference estimator and the equivalent input interference as a control input of the robot controlled system, and obtaining an output of the robot controlled system. The preset time equivalent input interference estimator is designed, so that the reconstruction speed of the estimator to the disturbance is improved, the disturbance estimation error is effectively reduced, and the comprehensive performance of the robot controlled system is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of robot anti-interference, and particularly relates to a robot active anti-interference and control method and device with preset time convergence. BACKGROUND

[0002] During the execution of a task by a robot, the system often faces the influence of interference factors such as changes in load inertia, unstructured external disturbance forces, friction, model mismatch, etc. These interferences can cause system oscillation, control precision decline, and further lead to increased trajectory tracking error and accelerated mechanical wear, and even affect the safe and stable operation of the system. In order to suppress such disturbances, in recent years, the Equivalent Input Disturbance (EID) estimator has been widely researched and applied. The core idea is to model the disturbance as a "virtual input" of the system, estimate and compensate the disturbance in real time through the construction of a state observer, so as to improve the anti-interference and tracking performance of the system.

[0003] Although the above method has achieved good results in many types of robot systems, its gradual stable form design, i.e. the system error gradually approaches zero in infinite time, makes the error convergence speed greatly affected by the initial state of the system, lacking precise control over the disturbance response time; and in high dynamic motion control of the robot, the slow error convergence speed will affect the real-time control precision of the system. Although the concept of "Prescribed-Time Observer" is proposed in the literature "Prescribed-Time Observers for Linear Systems in Observer Canonical Form", its design is based on the time-varying gain tending to infinity at a preset convergence time, achieving fixed-time convergence independent of the initial condition. However, its definition can only achieve a preset convergence time T, and there is no further design for the part exceeding the preset convergence time T, resulting in limited application scenarios. At the same time, its design is limited to state observers and cannot estimate and compensate external disturbances of the system. Therefore, a new disturbance estimation method is urgently needed, which not only realizes error stable zero in a preset time, but also has the characteristics of strong robustness, clear parameters, and excellent anti-noise performance in design, to meet the dual needs of fast response and high-precision disturbance compensation of the robot system. SUMMARY

[0004] The purpose of the present application is to provide a robot active anti-interference and control method and device with preset time convergence, which improves the reconstruction speed of the estimator for disturbances and effectively reduces the disturbance estimation error through the design of a preset time equivalent input disturbance estimator, thereby improving the comprehensive performance of the controlled system of the robot.

[0005] To achieve the above object, the technical scheme adopted by the present application is:

[0006] The first aspect provides a preset time convergent robot active anti-interference and control method, comprising:

[0007] constructing an equivalent input interference state space model of a robot controlled system;

[0008] constructing a preset time equivalent input interference estimator based on the equivalent input interference state space model, comprising: designing a variable scale function, and constructing a preset time state observer based on the equivalent input interference state space model and the variable scale function; and constructing a preset time filter based on the variable scale function;

[0009] given a reference input of the robot controlled system, the reference input obtains a control signal after passing through a controller, the control signal is taken as an input of the preset time equivalent input interference estimator, and an output of the preset time equivalent input interference estimator and the control signal are taken as a control input of the robot controlled system, so as to obtain an output of the robot controlled system.

[0010] The following also provides several optional modes, but not as an additional limitation of the above general scheme, just a further supplement or preferred, without technical or logical contradiction, each optional mode can be combined with the above general scheme alone, and can also be combined between multiple optional modes.

[0011] As a preferred, the constructing an equivalent input interference state space model of a robot controlled system comprises:

[0012] constructing a state space model containing a state of the robot controlled system, a control input of the robot controlled system and an external disturbance;

[0013] defining an equivalent input interference of the robot controlled system, removing the external disturbance in the state space model, and superimposing the equivalent input interference on the control input to obtain the equivalent input interference state space model.

[0014] As a preferred, the variable scale function contains two time periods, the first time period is from an observation starting time to a preset convergence time, and the second time period is from the preset convergence time to infinity;

[0015] and in the first time period, the function value of the variable scale function is monotonically increasing, and when approaching the preset convergence time, the function value of the variable scale function tends to positive infinity; in the second time period, the function value of the variable scale function is a constant value.

[0016] As preferred, the derivative of the state of the robot controlled system estimated by the preset time state observer comprises three parts, respectively: the state of the robot controlled system estimated by the preset time state observer, the output of the controller, and a gain term.

[0017] The gain term is the product of the difference between the output of the robot controlled system and the output of the robot controlled system estimated by the preset time state observer, and the gain of the preset time state observer.

[0018] As preferred, the gain of the preset time state observer is designed as a recursive function of the variable scale function which is monotonically increasing within the preset convergence time.

[0019] As preferred, the estimation error of the preset time state observer is the difference between the real state of the robot controlled system and the state estimated by the preset time state observer.

[0020] The equivalent input disturbance estimation value output by the preset time state observer is the product of the gain matrix of the preset time state observer of all orders of the robot controlled system, the estimation error matrix of the preset time state observer of all orders of the robot controlled system, and the generalized inverse of the input matrix of the robot controlled system.

[0021] As preferred, the time constant term of the preset time filter introduces a variable scale function, and the output of the preset time filter is positively correlated with the inverse of the variable scale function.

[0022] The second aspect provides a preset time convergence robot active anti-interference and control device, comprising a processor and a memory storing a plurality of computer instructions, and the computer instructions are executed by the processor to realize the steps of the preset time convergence robot active anti-interference and control method.

[0023] In order to reduce the influence of the change of load inertia of the robot controlled system, external disturbance and other factors on the motion control performance during operation, and at the same time consider the interference of measurement noise on the disturbance estimation accuracy and the overall performance of the system, the present application based on the equivalent input disturbance estimator, proposes a preset time convergence robot active anti-interference and control method and device. The method designs an equivalent input disturbance estimator based on preset time, and the control architecture comprises a preset time state observer and a preset time filter. The preset time equivalent input disturbance estimator realizes accurate estimation of the total disturbance of the system within the preset convergence time by designing a variable scale function, and introduces a compensation signal of the disturbance estimation in the control input of the motion system, so as to realize active suppression of the total disturbance of the system. By designing the preset time observer, the disturbance estimation error is effectively reduced, so as to improve the comprehensive performance of the robot controlled system. The method of the present application provides important technical support for high-precision control of robots. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 This is a flowchart of the robot active anti-interference and control method with preset time convergence according to the present invention;

[0025] Figure 2 This is a control block diagram of the preset time equivalent input interference estimator of the present invention;

[0026] Figure 3 This is a trajectory comparison diagram of the comparative experiment conducted in the motion control system of the robotic arm according to the present invention;

[0027] Figure 4 This is a comparison diagram of the position-step trajectory on a two-dimensional plane in the comparative experiment of the present invention in the motion control system of the robotic arm.

[0028] Figure 5 This is a two-dimensional plane comparison diagram of contact force and step count in the comparative experiment of the present invention in the motion control system of the robotic arm. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0031] Example 1:

[0032] like Figure 1 As shown, this embodiment provides a robot active anti-interference and control method with preset time convergence, applicable to linear dynamic systems with observable structures, including the following steps:

[0033] Step 1: Construct the equivalent input disturbance state space model of the robot controlled system.

[0034] First, a state-space model is constructed, including the state of the robot controlled system, the control input of the robot controlled system, and external disturbances, as follows:

[0035]

[0036] Then, equivalent input disturbance control is introduced, and the definition is... for The equivalent input disturbance state space model of the robot controlled system at time t is:

[0037]

[0038] wherein is the state of the robot controlled system at time t, is the derivative of the state , is the control input of the robot controlled system at time t, is the output of the robot controlled system at time t, is the state matrix, the input matrix and the output matrix of the robot controlled system with controllability and observability respectively, denotes the external disturbance, is the gain matrix corresponding to the external disturbance.

[0039] Step 2, as shown in Figure 2 , the preset time equivalent input disturbance estimator is constructed based on the equivalent input disturbance state space model, including: designing a variable scale function, and constructing a preset time state observer based on the equivalent input disturbance state space model and the variable scale function; and constructing a preset time filter based on the variable scale function.

[0040] Step 2-1, designing a variable scale function: the variable scale function obtained in this embodiment contains two time periods, the first time period is from the observation starting time to the preset convergence time, and the second time period is from the preset convergence time to infinity; and in the first time period, the function value of the variable scale function is monotonically increasing, and the function value of the variable scale function tends to positive infinity when approaching the preset convergence time; in the second time period, the function value of the variable scale function is a constant value. A variable scale function satisfying the above conditions provided in this embodiment is as follows:

[0041]

[0042] wherein is the preset convergence time, which is set to 0.15 seconds in this embodiment, is the observation starting time, which is set to 0 seconds in this embodiment, is a positive design parameter, and the function value of the variable scale function is monotonically increasing in the time period and tends to infinity at .

[0043] Step 2-2: Based on the variable scaling function and the equivalent input disturbance state space model, design a preset time observer, and obtain the state observation value based on the output of the robot controlled system and the gain of the preset time state observer.

[0044] In this embodiment, the derivative of the robot-controlled system's state estimated by the preset time state observer comprises three parts: the estimated state term of the robot-controlled system, the controller's output term, and the gain term. The gain term is the product of the difference between the robot-controlled system's output and the output estimated by the preset time state observer, and the gain of the preset time state observer. The formula is expressed as follows:

[0045]

[0046] In the formula yes The state (i.e., state observation value) estimated by the time-preset state observer is set at a certain time. It is the estimated state. The derivative of It is the output of the controller. yes Output of the robot controlled system The estimated value, This is the gain of the preset time-state observer, which is designed as a monotonically increasing recursive function with respect to a variable scaling function within a preset convergence time, expressed by the following formula:

[0047] when At that time, the gain is expressed as follows:

[0048]

[0049] when When the gain is given, it is expressed as follows:

[0050]

[0051] In the formula, Let the total order of the robot-controlled system be denoted as . and These are the ordinal numbers of the order, Indicates the preset time state observer number The gain of the order, For the first The first constant of order, It is the second constant. To preset the convergence time, For the first order to the second order The change value of the order, For the first order to the second order The change value of the order, represents the gain of the preset time state observer at the i-th order, is the first constant of the i-th order, is the change value from the i-th order to the (i+1)-th order, is the power of the variable scale function represents the gain of the preset time state observer at the i-th order, is the first constant of the i-th order, is the change value from the i-th order to the (i+1)-th order, is the change value from the i-th order to the (i+1)-th order, is the power of the variable scale function is the change value from the i-th order to the (i+1)-th order, is the change value from the i-th order to the (i+1)-th order, is the power of the variable scale function is the power of the variable scale function

[0052] And the change value setting rule is as follows:

[0053] When , the value of the change value is 1;

[0054] When , the value of the change value is 0;

[0055] When , if , the value of the change value is , at this time, it satisfies ; if , the value of the change value is , at this time, it satisfies ; wherein is the change value from the i-th order to the (i+1)-th order, is the change value from the i-th order to the (i+1)-th order.

[0056] Step 2-3, define the estimation error of the preset time state observer as the true state of the robot controlled system and the state estimated by the preset time state observer ​​​​​​​​​​​​​​​​​the difference between the preset time state observer and the real state of the robot controlled system, combined with the order of the robot controlled system, the estimation error of the preset time state observer of the first order is obtained , so that the dynamic estimation error can be obtained as follows:

[0057]

[0058] where is the real state of the robot controlled system of the first order at time is the estimated state of the preset time state observer of the first order at time is the estimation error of the first order is the derivative of the estimation error of the first order is the estimation error of the first order of the preset time state observer is the derivative of the estimation error of the first order is the estimation error of the first order of the preset time state observer is the derivative of the estimation error of the first order is the estimation error of the first order of the preset time state observer is the estimation error of the first order of the preset time state observer .

[0059] By introducing a specific time-varying coordinate transformation for the observer error state and selecting a corresponding time-varying observer gain , the preset time stability of the above dynamic error can be achieved. Under this design, the error system converges within a preset convergence time , which is independent of the initial conditions.

[0060] The equivalent input disturbance estimation value of the preset time state observer output is The gain matrix of the preset time state observer of all orders , the estimation error matrix of the preset time state observer of all orders , and the generalized inverse of the input matrix of the robot controlled system are multiplied. The formula is expressed as .

[0061] Step 2-4, since the estimation error is used to calculate the preset time equivalent input disturbance estimator estimation, if the equivalent input disturbance estimation value is directly used to compensate for external disturbances , there is a causality problem. Therefore, it is necessary to filter and obtain the filtered equivalent input disturbance estimation value . According to the variable scale function ​​The preset time filter is designed, and in the embodiment, a time constant term of the preset time filter introduces a variable scale function, and the preset time filter is positively correlated with the inverse of the variable scale function. In the embodiment, the time constant term provides a specific way of taking the inverse of the variable scale function, and then subtracting the inverse of the variable scale function from 1 and multiplying the result by the time constant. The formula is as follows:

[0062]

[0063] In the formula, is the preset time filter, , is the filter time constant, is the time constant term of the preset time filter after introducing the variable scale function.

[0064] Step 3, given the reference input of the robot controlled system , the reference input passes through the controller to obtain the control signal , the control signal is taken as the input of the preset time equivalent input disturbance estimator to obtain the output of the preset time equivalent input disturbance estimator , the output and the control signal are taken as the control input of the robot controlled system , and the output of the robot controlled system is obtained .

[0065] In the mechanical arm motion control system, a time-varying contact force is applied to the mechanical arm to test the performance of the method (referred to as PTEID method) under dynamic interaction conditions. The comparison method is the traditional equivalent input disturbance estimator (referred to as EID method). The experiment shows the results in the time-varying contact force field: Figure 3 shows the trajectory of the end effector, which is a comparison chart of position and standardized step number; Figure 4 (a) and Figure 4 (b) show the trajectories in the x and y directions, respectively; Figure 5 (a) and Figure 5 (b) show the estimation results of the contact force (in Newton) applied in the x and y directions. Obviously, the method of the present application can provide faster and more accurate force estimation than the traditional equivalent input disturbance estimator, and the control speed and control accuracy are effectively improved.

[0066] Embodiment 2:

[0067] The embodiment provides a preset-time convergent robot active anti-interference and control device, which comprises a processor and a memory storing a plurality of computer instructions, and the computer instructions are used to realize steps of a preset-time convergent robot active anti-interference and control method when the processor executes the computer instructions.

[0068] The specific limitation of the preset-time convergent robot active anti-interference and control device can refer to the limitation of the preset-time convergent robot active anti-interference and control method, which will not be repeated here.

[0069] The memory and the processor are directly or indirectly electrically connected to realize the transmission or interaction of data. For example, the elements can be electrically connected to each other through one or more communication buses or signal lines. The memory stores a computer program that can run on the processor, and the processor realizes the method by running the computer program stored in the memory.

[0070] The memory can be, but is not limited to, a random access memory (RAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM) and the like. The memory is used to store a program, and the processor executes the program after receiving an execution instruction.

[0071] The processor can be an integrated circuit chip with data processing capability. The processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP) and the like. The processor can realize or execute the methods, steps and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0072] The technical features of the above-described embodiments can be combined in any manner. In order to make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist contradictions, it should be considered that the combinations are within the scope of the present disclosure.

[0073] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but should not be understood as a limitation on the scope of the application. It should be noted that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, which are within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A preset time convergent robot active anti-jamming and control method, characterized in that, The preset-time converging robot active anti-interference and control method comprises the following steps: An equivalent input interference state space model of a robot controlled system is constructed; The preset time equivalent input disturbance estimator is constructed based on the equivalent input disturbance state space model, comprising: designing a variable scale function, and constructing a preset time state observer based on the equivalent input disturbance state space model and the variable scale function; and constructing a preset time filter based on the variable scale function; wherein the variable scale function is designed as follows: as follows: ； In the formula is a preset convergence time, is an observation start time, is a positive design parameter; and the time constant term of the preset time filter introduces a variable scale function, and the output of the preset time filter is positively correlated with the inverse of the variable scale function; A reference input of the robot controlled system is given, and the reference input is used to obtain a control signal after passing through a controller.

2. The pre-set time converging robot active anti-jamming and control method of claim 1, wherein, The control signal is used as an input of a preset-time equivalent input interference estimator. The output of the preset-time equivalent input interference estimator and the control signal are used as a control input of the robot controlled system to obtain an output of the robot controlled system. The preset-time converging robot active anti-interference and control method comprises the following steps:

3. The pre-set time converging robot active anti-jamming and control method of claim 1, wherein, An equivalent input interference state space model of a robot controlled system is constructed; A state space model containing the state of the robot controlled system, the control input of the robot controlled system and external disturbance is constructed.

4. The pre-set time converging robot active anti-jamming and control method of claim 3, wherein, An equivalent input interference of the robot controlled system is defined, the external disturbance in the state space model is removed, and the equivalent input interference is superimposed on the control input to obtain the equivalent input interference state space model.

5. The pre-set time converging robot active anti-jamming and control method of claim 1, wherein, The variable scale function comprises two time periods. In the first time period from the observation start time to the preset convergence time, the function value of the variable scale function monotonically increases, and when approaching the preset convergence time, the function value of the variable scale function tends to positive infinity.

6. The pre-set time converging robot active anti-jamming and control method of claim 1, wherein, In the second time period, the function value of the variable scale function is a constant value. The gain of the preset-time state observer is designed as a recursive function of the variable scale function which monotonically increases in the preset convergence time.

7. A preset time convergent robot active anti-jamming and control device, comprising a processor and a memory having a plurality of computer instructions stored therein, characterized in that, The derivative of the estimated state of the robot controlled system of the preset-time state observer comprises three parts, which are the estimated state of the robot controlled system, the output of the controller and the gain term. The gain term is the product of the difference between the output of the robot controlled system and the estimated output of the robot controlled system of the preset-time state observer and the gain of the preset-time state observer. The estimation error of the preset-time state observer is the difference between the true state of the robot controlled system and the estimated state of the preset-time state observer. The equivalent input interference estimation value output by the preset-time state observer is the product of the gain matrix of the preset-time state observer of all orders of the robot controlled system, the estimation error matrix of the preset-time state observer of all orders of the robot controlled system and the generalized inverse of the input matrix of the robot controlled system. The computer instructions are executed by the processor to realize the steps of the preset-time converging robot active anti-interference and control method in any one of claims 1 to 6.

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