Hydraulic excavator control method, device and hydraulic excavator

Abstract

The present application provides a hydraulic excavator control method, device and hydraulic excavator, the method comprising: determining a target PID control parameter according to the current driving stage in each sampling period; calculating an integral suppression parameter according to the trajectory deviation at the current moment; calculating an integral control parameter according to the trajectory deviation, a target control amount at the previous moment, and a final control amount at the previous moment; calculating a PID control output according to the integral suppression parameter, the integral control parameter, and the target PID control parameter; determining a target dead zone offset compensation currently used according to the PID control output, and compensating the PID control output according to the target dead zone offset compensation to obtain the target control amount at the current moment; using a saturation function to limit the target control amount to obtain the final control amount at the current moment, and controlling the actuator according to the final control amount.

Description

Technical Field

[0001] The present application relates to the technical field of hydraulic excavators, and in particular to a hydraulic excavator control method, device and hydraulic excavator. Background Art

[0002] As an important engineering equipment, hydraulic excavator plays a key role in modern construction, mining and infrastructure construction. In recent years, in order to improve production efficiency, reduce energy consumption, ensure safety and reduce operating burden, hydraulic excavator intelligent control technology has gradually emerged.

[0003] There are many types of construction contents for hydraulic excavators. Different driving forms are required according to the types of tasks and operation characteristics. In the execution of typical tasks such as shifting and excavation, there are a large number of links executed with single joint timing, such as the rotation of the bucket, unloading, and lifting of the boom. When performing tasks, hydraulic excavators not only have system flow coupling (the flow of each hydraulic component in the hydraulic system affects each other, causing changes in system flow to affect the working state of other components, thereby causing nonlinear system behavior), but are also affected by inertia and the nonlinearity of the hydraulic system structure. These nonlinear effects cause conventional control methods to have insufficient control accuracy and stability for hydraulic excavators. Therefore, how to intelligently control hydraulic excavators to solve the problem of insufficient control accuracy and stability of hydraulic excavators caused by the strong nonlinearity of the electromechanical-hydraulic coupling system has become the focus of current research. Summary of the invention

[0004] In view of this, the present application provides a hydraulic excavator control method, device and hydraulic excavator, so as to provide a control method to solve the problem of insufficient control accuracy and stability of the hydraulic excavator due to the strong nonlinearity of the electromechanical-hydraulic coupling system.

[0005] Specifically, the present application is implemented through the following technical solutions:

[0006] A first aspect of the present application provides a hydraulic excavator control method, the method comprising:

[0007] For the actuator to be controlled, in each sampling period, according to the current driving stage, a target PID control parameter corresponding to the current driving stage is determined; wherein different driving stages correspond to different PID control parameters;

[0008] Calculating an integral suppression parameter according to the trajectory deviation at the current moment; wherein the integral suppression parameter increases as the trajectory deviation decreases;

[0009] Calculating an integral control parameter according to the trajectory deviation, the target control amount at the previous moment, and the final control amount at the previous moment;

[0010] Calculating a PID control output according to the integral suppression parameter, the integral control parameter, and the target PID control parameter;

[0011] Determine the target dead zone offset compensation currently used according to the PID control output, and compensate the PID control output according to the target dead zone offset compensation to obtain the target control amount at the current moment;

[0012] The target control amount is limited by using a saturation function to obtain a final control amount at the current moment, and the actuator is controlled according to the final control amount.

[0013] A second aspect of the present application provides a hydraulic excavator control device, which is applied to a hydraulic excavator and includes a control module, a parameter adjustment module and an output compensation module; wherein:

[0014] The parameter adjustment module is used to determine, for the actuator to be controlled, a target PID control parameter corresponding to the current driving stage according to the current driving stage in each sampling period; wherein the PID control parameters corresponding to different driving stages are different;

[0015] The parameter adjustment module is used to calculate an integral suppression parameter according to the trajectory deviation; wherein the integral suppression parameter increases as the trajectory deviation decreases;

[0016] The parameter adjustment module is used to calculate the integral control parameter according to the trajectory deviation, the target control amount at the previous moment, and the final control amount at the previous moment;

[0017] The control module is used to calculate the PID control output according to the integral suppression parameter, the integral control parameter, and the target PID control parameter;

[0018] The output compensation module is used to determine the target dead zone offset compensation currently adopted according to the PID control output, and compensate the PID control output according to the target dead zone offset compensation to obtain the target control amount at the current moment;

[0019] The output compensation module is further used to use a saturation function to perform a limiting operation on the target control amount to obtain a final control amount at the current moment, and control the actuator according to the final control amount.

[0020] The third aspect of the present application provides a hydraulic excavator, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of any one of the methods provided in the first aspect of the present application are implemented.

[0021] The fourth aspect of the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any one of the methods provided in the first aspect of the present application.

[0022] The hydraulic excavator control method, device and hydraulic excavator provided by the present application, on the first hand, by determining the target PID control parameters corresponding to the current driving stage, different PID control parameters can be selected in different driving stages to adapt to the control asymmetry caused by load influence and improve the control accuracy; on the second hand, in the present application, when calculating the PID control output, through the integral control parameters, the integration can be stopped when the system deviation and the output control deviation are in the same direction, and the integration can be strengthened in the opposite direction, thereby ensuring that the adjustment time is shortened without affecting the steady-state accuracy and improving the dynamic performance of the cylinder system. Through the integral suppression parameter, the integral action can be suppressed when the system deviation is large, preventing integral saturation and excessive overshoot, and dominating the output control amount when the system deviation is small, which is conducive to further improving the steady-state accuracy; on the third aspect, in the present application, after the PID control output is calculated, the target dead zone offset compensation is determined according to the PID control output, and then the PID control output is compensated using the target dead zone offset compensation. In this way, on the one hand, the control dead zone phenomenon can be avoided, and then the nonlinear relationship between the control current and the valve core displacement caused by the dead zone phenomenon can be avoided, thereby avoiding the problem of low control accuracy caused by the nonlinear relationship, and improving the control accuracy; on the other hand, through compensation, the problem of the control amount generating current being insufficient to drive the valve core to generate flow due to the small trajectory deviation can be avoided, and then the problem of insufficient control accuracy and stability caused by the control amount generating current being insufficient to drive the valve core to generate flow can be avoided, and the control accuracy and control stability can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A flowchart of a first embodiment of a hydraulic excavator control method provided in the present application;

[0024] Figure 2 A flowchart of a second embodiment of a hydraulic excavator control method provided in this application;

[0025] Figure 3 A control principle diagram of a hydraulic excavator shown as an exemplary embodiment of the present application;

[0026] Figure 4 This is a schematic diagram of the step response of each joint when the hydraulic excavator is controlled by the traditional PID control method;

[0027] Figure 5 This is a schematic diagram of the step response of each joint after the response speed is improved according to an exemplary embodiment of the present application;

[0028] Figure 6 This is a rendering of a sinusoidal signal tracking experiment based on the hydraulic excavator control method provided by the present application;

[0029] Figure 7 This is a rendering of an excavation operation trajectory shown in an exemplary embodiment of the present application;

[0030] Figure 8 A hardware structure diagram of the hydraulic excavator in which the hydraulic excavator control device provided in this application is located;

[0031] Fig. 9 This is a structural schematic diagram of Example 1 of the hydraulic excavator control device provided in this application. DETAILED DESCRIPTION

[0032] Here, exemplary embodiments are described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application.

[0033] The terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used in this article refers to and includes any or all possible combinations of one or more associated listed items.

[0034] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope 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 word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0035] Specific embodiments are given below to introduce the technical solution of the present application in detail.

[0036] Figure 1 This is a flow chart of the first embodiment of the hydraulic excavator control method provided by this application. Figure 1 , the method provided in this embodiment may include:

[0037] S101. For an actuator to be controlled, in each sampling period, according to the current driving stage, determine a target PID control parameter corresponding to the current driving stage; wherein different driving stages correspond to different PID control parameters.

[0038] Specifically, the hydraulic excavator control method and device provided in this embodiment are applied to the hydraulic excavator to control the hydraulic excavator. When implemented specifically, they can be applied to the controller of the hydraulic excavator.

[0039] The actuator to be controlled can be the boom, dipper arm, bucket, rotation, etc. on the hydraulic excavator. It should be noted that when the hydraulic excavator performs certain tasks, there are links that are performed by a single joint. At this time, the single joint needs to be independently controlled. The single joint is the actuator to be controlled. For example, in typical tasks such as shifting and excavation, it is necessary to control the rotation of the bucket. At this time, the bucket is the actuator to be controlled. For another example, in certain tasks, it is necessary to control the lifting of the boom. At this time, the boom is the actuator to be controlled. The following explanation takes the boom as an example of the actuator to be controlled.

[0040] It should be noted that the sampling period refers to the time interval between each control calculation and output of the control command by the hydraulic excavator. The sampling period is set according to actual needs and is not limited in this embodiment.

[0041] It should be noted that due to the asymmetry of the hydraulic cylinder and the load of the hydraulic excavator drive, the hydraulic system is directional, that is, there is a forward drive stage and a reverse drive stage.

[0042] Specifically, the forward driving phase and the reverse driving phase of the hydraulic excavator refer to two different phases of the excavator's execution of actions, which phases usually occur when the hydraulic excavator performs a specific operation.

[0043] In the forward drive phase, the hydraulic system applies force to push the excavator to perform specific actions, such as lifting the arm, extending the dipper, opening the bucket, etc. In this phase, the work of the hydraulic cylinder or hydraulic motor increases the energy of the system, so that the excavator's actuator moves in the specified direction. For example, when the excavator needs to extend the digging range, the hydraulic system will apply force to push the dipper forward.

[0044] In the reverse drive phase, the hydraulic system reverses its action to perform the opposite action. For example, retracting the arm, retracting the dipper, closing the bucket, etc. In this phase, the working direction of the hydraulic cylinder or hydraulic motor changes, and the direction of the force is opposite to that in the forward drive phase. For example, when the excavator needs to retract the dipper to fit into a narrow working space, the hydraulic system will apply force to retract the dipper.

[0045] It is understandable that, when the valve body parameters are the same, there are certain differences in the forward and reverse driving characteristics, which may lead to differences in the forward and reverse direction of the position servo tracking error under the same control structure.

[0046] However, according to the hydraulic excavator drive test, the forward and reverse hydraulic cylinders run at stable and similar speeds with the same control amount. The reason is that in actual situations, the proportional valve parameters of the hydraulic excavator will be fine-tuned according to the flow characteristics of the hydraulic cylinder to structurally compensate for the directionality of the hydraulic system. Therefore, the influence of the asymmetric hydraulic cylinder flow characteristics is ignored in the control.

[0047] Different PID control parameters are designed to deal with the control asymmetry caused by load influence, that is, different PID control parameters are used when the current driving stage is different.

[0048] In a specific implementation, in a possible implementation, the target PID control parameter can be determined according to the following method:

[0049] When the current driving stage is the forward driving stage, the target PID control parameters are determined to be the first group of control parameters; when the current driving stage is the reverse driving stage, the target PID control parameters are determined to be the second group of control parameters; wherein each parameter in the first group of control parameters is greater than each parameter in the second group of control parameters.

[0050] It can be understood that the PID control parameters include proportional gain, integral gain and differential gain. It is the proportional gain. Generally, the response speed of the system is proportional to its size. However, if it is too large, it may cause the system to oscillate or even diverge. It is the integral gain, which reflects the accumulation of deviation and can improve the system response, but it is mainly used to eliminate the steady-state error of the system. Too large a value can easily lead to system instability. The reason is that the integration in the large deviation stage often causes the system response to overshoot too much, and at the same time causes the adjustment time to become longer. It is the differential gain, which is proportional to the rate of change of the system error. It can shorten the steady-state adjustment time. However, the error change rate is easily affected by system interference. When the interference is too large, the error change rate cannot reflect the true free convergence situation and may aggravate the system oscillation.

[0051] For the convenience of explanation, the first set of control parameters is recorded as: , , The second set of control parameters is recorded as: , , ,in, , , .

[0052] It should be noted that in the forward driving stage, the driving area is large, the load is large, and the impedance mode is used. Therefore, in the forward driving stage, the PID control parameters are set relatively large.

[0053] S102. Calculate an integral suppression parameter according to the trajectory deviation at the current moment; wherein the integral suppression parameter increases as the trajectory deviation decreases.

[0054] Specifically, in a possible implementation, the integral suppression parameter may be calculated according to the following formula:

[0055] ,

[0056] Among them, the is the integral suppression parameter; is a preset coefficient less than 0; is the trajectory deviation.

[0057] S103, calculating an integral control parameter according to the trajectory deviation, the target control amount at the previous moment, and the final control amount at the previous moment.

[0058] In specific implementation, the integral control parameter can be calculated according to the following formula:

[0059] ,

[0060] ,

[0061] Among them, the is the integral control parameter, is the trajectory deviation, is the target control amount at the previous moment, is the final control amount at the previous moment.

[0062] It should be noted that, from the above formula, the final control quantity when the output is saturated is It will no longer change with the target control amount. At this time, the trajectory deviation If the output deviation (output deviation is ) have the same sign, then Will be set to 0 to implement the limiting operation of the integral link. On the contrary, if the trajectory deviation and the output deviation have opposite signs, it indicates that it is in the clearing integral stage. Set to 1 to restore normal integration, thereby ensuring that dynamic performance is improved without affecting steady-state accuracy.

[0063] S104, calculating a PID control output according to the integral suppression parameter, the integral control parameter, and the target PID control parameter.

[0064] In a specific implementation, in a possible implementation manner, the specific implementation process of this step may include:

[0065] (1) Calculating an output of an integral controller according to the integral suppression parameter, the integral control parameter, and a proportional gain and an integral gain among the target PID control parameters.

[0066] In specific implementation, the output of the integral controller can be calculated by referring to the following formula:

[0067] ,

[0068] Among them, the is the output of the integral controller;

[0069] Said is the proportional gain;

[0070] Said is the integral gain;

[0071] Said is the integral control parameter;

[0072] Said is the integral suppression parameter;

[0073] Said is the trajectory deviation;

[0074] Said is the sampling period.

[0075] After discretization, the output of the integral controller can be calculated according to the following formula:

[0076] ,

[0077] in, is the output of the integral controller, is the proportional gain, is the integral gain, is the integral control parameter, is the integral suppression parameter, is the trajectory deviation within the sampling period, Equal to 0 to t.

[0078] (2) Calculate the output of the proportional controller and the output of the differential controller according to the proportional coefficient and the differential coefficient in the target PID control parameters.

[0079] Specifically, the output of the differential controller can be calculated as follows:

[0080] ,

[0081] in, is the output of the derivative controller, is the differential gain in the target PID control parameter, is the proportional gain in the target PID control parameter.

[0082] After discretization, the output of the derivative controller can be calculated according to the following formula:

[0083] ,

[0084] in, is the output of the differential controller at time t, is the sampling period of the control system. is the trajectory deviation at the current moment, is the trajectory deviation at the previous moment.

[0085] Similarly, the output of the proportional controller can be calculated as follows:

[0086] ,

[0087] in, is the output of the proportional controller at time t, is the trajectory deviation at the current moment, is the proportional gain in the target PID control parameter.

[0088] (3) Calculating the PID control output amount based on the output of the proportional controller, the output of the integral controller, and the output of the differential controller.

[0089] Specifically, the PID control output is calculated according to the following formula:

[0090] ,

[0091] in: is the PID control output; is the output of the proportional controller, the is the output of the integral controller, is the output of the differential controller.

[0092] That is, the PID control output can be calculated according to the following formula:

[0093] ;

[0094] After discretization, the PID control output can be calculated according to the following formula:

[0095] .

[0096] It should be noted that ,make ,make , the above formula can be simplified to:

[0097] .

[0098] It should be noted that the control of the hydraulic system of a hydraulic excavator must not only meet the accuracy requirements, but also take safety into consideration. As heavy engineering equipment, it is necessary to ensure that the working device is controlled to run at medium and low speeds without causing large overshoot.

[0099] However, due to the hysteresis effect of integral control, the rise time is relatively long when the step response has a large deviation. The integration of the error by the PID controller may cause the output to reach saturation. Continuing the integration will make it difficult to eliminate the integral value after the error reverses, causing a large overshoot of the system, and also prolonging the adjustment time of the system. In this application, the overshoot effect during the response rise process is suppressed by reducing the error overshoot under the starting conditions, so that the excavator PID control can obtain good response performance.

[0100] In summary, in order to improve the performance of the single working device hydraulic cylinder PID controller and further optimize the PID control strategy, in this application, the integral control parameter can be used to suppress the integral effect when the system deviation is large. The integral suppression parameter can stop the integration when the output is saturated.

[0101] According to the calculation formula of the integral suppression parameter, the final control amount when the output is saturated is It will no longer change with the target control amount. At this time, the trajectory deviation If the output deviation (output deviation is ) have the same sign, then Will be set to 0 to implement the limiting operation of the integral link. On the contrary, if the trajectory deviation and the output deviation have opposite signs, it indicates that it is in the clearing integral stage. Set to 1 to restore normal integration, thereby ensuring that dynamic performance is improved without affecting steady-state accuracy.

[0102] The calculation formula of the integral control parameter shows that in the initial stage of response, the trajectory deviation is large. Smaller, through It can inhibit the integral link of the PID controller and prevent excessive overshoot caused by integral saturation. After that, as the control proceeds, the trajectory deviation gradually decreases. It gradually increases until it reaches the maximum value when the control amount is close to the target value. At this time, the integral link dominates the output control amount, which is beneficial to improve the steady-state accuracy.

[0103] It should be noted that in the actual deployment process, in order to reduce the controller overhead, the incremental method is used instead of the position control, and the final control amount is calculated according to the following formula:

[0104] .

[0105] The hydraulic excavator control method provided in this embodiment can suppress the integral action when the system deviation is large and stop the integration when the output is saturated through the integral suppression parameter and the integral control parameter, thereby further improving the control performance and improving the control accuracy and stability.

[0106] S105 . Determine a target dead zone offset compensation currently used according to the PID control output, and compensate the PID control output according to the target dead zone offset compensation to obtain a target control amount at a current moment.

[0107] It should be noted that an important factor in the nonlinear characteristics of the hydraulic system is the dead zone phenomenon of the control, which mainly exists in the pilot proportional valve and main valve link of the hydraulic system in the hydraulic excavator. The existence of the dead zone greatly affects the performance of the control system. On the one hand, it will cause a strong nonlinear relationship between the control current and the valve core displacement, so that the control amount cannot be completely converted into the output flow, resulting in a decrease in the dynamic performance of the control. On the other hand, when there is a small trajectory deviation, the current generated by the control amount will not be enough to drive the valve core to generate flow, resulting in a decrease in the steady-state accuracy of the system control. Therefore, in order to improve the control performance, it is necessary to compensate the PID control output.

[0108] In specific implementation, the target dead zone offset compensation can be calculated according to the following formula:

[0109] (1) When the PID control output is greater than zero, the target dead zone offset compensation is determined to be a positive dead zone compensation amount; wherein the positive dead zone compensation amount is a critical control amount when the actuator generates a positive motion from an intermediate position when the control amount increases positively from 0.

[0110] (2) When the PID control output is equal to 0, the target dead zone offset compensation is determined to be 0.

[0111] (3) When the PID control output is less than 0, the target dead zone offset compensation is determined to be a negative dead zone compensation amount; wherein the negative dead zone compensation amount is a critical current value when the actuator generates a negative movement from the intermediate position when the control amount increases negatively from 0.

[0112] As described above, the target dead zone offset compensation is related to the direction of the PID control output. The target dead zone offset compensation can be determined according to the following formula:

[0113] ,

[0114] in, is the PID control output; Represents the target dead zone compensation amount; Represents the positive dead zone compensation amount; Represents the negative dead zone compensation amount.

[0115] It should be noted that the positive dead zone compensation and negative dead zone compensation are obtained through experimental measurement. In addition, since each valve core is independently driven and has different control characteristics, different actuators correspond to different positive dead zone compensation and different negative dead zone compensation, which need to be measured separately.

[0116] The following takes the boom as an example to illustrate the method of obtaining the positive dead zone compensation and the negative dead zone compensation. Specifically, the boom, dipper stick, bucket, etc. are initialized to the middle position of the working range, and other actuators are turned off to independently control the boom. After that, the controller starts to increase the current from I=0mA in a positive direction until the boom generates positive movement and records the critical current value at this time. The critical current value is the positive dead zone compensation. Furthermore, the controller starts to increase the current from I=0mA in a negative direction, that is, the current is applied to the other side of the valve core until the boom generates negative movement and records the critical current value at this time. The critical current value is the negative dead zone compensation. It should be noted that the positive dead zone compensation and negative dead zone compensation of other actuators can be obtained by similar experiments, which will not be repeated here.

[0117] It should be noted that the experiment also calculated the dead zone compensation amount at different initial positions, but since the change of the dead zone compensation amount calculated from different initial positions is very small, the influence of the initial position on the dead zone compensation amount is ignored here. Referring to Table 1, Table 1 shows the dead zone compensation amount of each actuator shown in an exemplary embodiment of the present application:

[0118] Table 1

[0119]

[0120] Specifically, when compensating the PID control output according to the target dead zone offset compensation, the target dead zone offset compensation can be directly added to the PID control output to obtain the target control amount at the current moment.

[0121] That is, when the PID control output is compensated according to the target dead zone offset compensation, the PID control output may be compensated according to the following formula:

[0122] ,

[0123] in, is the target control amount at the current moment, is the PID control output at the current moment, is the target dead zone offset compensation.

[0124] S106. Using a saturation function, perform a limiting operation on the target control amount to obtain a final control amount at the current moment, and control the actuator according to the final control amount.

[0125] Specifically, the target control amount can be limited according to the following method:

[0126] ,

[0127] in, is the final control amount; is the target control amount at the current moment; is a saturation function.

[0128] Specifically, when the target control amount reaches the saturation upper limit, due to the effect of the saturation function, the final control amount no longer increases, and the final control amount output at this time is the saturation upper limit. It should be noted that the saturation upper limit is determined by the current output capacity of the hydraulic excavator.

[0129] The hydraulic excavator control method provided in this embodiment, on the one hand, by determining the target PID control parameters corresponding to the current driving stage, different PID control parameters can be selected in different driving stages to adapt to the control asymmetry caused by load influence and improve the control accuracy; on the second hand, in this application, when calculating the PID control output, through the integral control parameters, it is possible to stop the integration when the system deviation and the output control deviation are in the same direction, and strengthen the integration when they are in the opposite direction, thereby ensuring that the adjustment time is shortened without affecting the steady-state accuracy and improving the dynamic performance of the cylinder system. Through the integral suppression parameter, the integral action can be suppressed when the system deviation is large, preventing integral saturation and excessive overshoot, and dominating the output control amount when the system deviation is small, which is conducive to further improving the steady-state accuracy; thirdly, after calculating the PID control output, the target dead zone offset compensation is determined according to the PID control output, and then the PID control output is compensated by using the target dead zone offset compensation. In this way, on the one hand, the control dead zone phenomenon can be avoided, and then the nonlinear relationship between the control current and the valve core displacement caused by the dead zone phenomenon can be avoided, thereby avoiding the problem of low control accuracy caused by the nonlinear relationship, and improving the control accuracy; on the other hand, through compensation, the problem that the control amount generated current is insufficient to drive the valve core to generate flow due to the small trajectory deviation can be avoided, and then the problem of insufficient control accuracy and stability caused by the control amount generated current is insufficient to drive the valve core to generate flow can be avoided, and the control accuracy and control stability can be improved.

[0130] Figure 2 This is a flow chart of Embodiment 2 of the hydraulic excavator control method provided in this application. Figure 3 This is a control schematic diagram of a hydraulic excavator shown in an exemplary embodiment of the present application. Figure 2 and Figure 3 The hydraulic excavator control method provided in this embodiment may include:

[0131] S201 . For an actuator to be controlled, in each sampling period, calculate a deviation change rate according to a trajectory deviation of the actuator at the current moment.

[0132] Specifically, the trajectory deviation of the actuator to be controlled at the current moment represents the difference between the actual trajectory and the target trajectory of the actuator to be controlled at the current moment.

[0133] In specific implementation, the deviation change rate can be calculated according to the following formula:

[0134] ,

[0135] in, is the trajectory deviation at the current moment;

[0136] e˙(t) is the calculated deviation change rate.

[0137] It should be noted that after discretization, the deviation change rate can be calculated according to the following formula:

[0138] ,

[0139] Wherein, e˙(k) is the calculated deviation change rate; is the trajectory deviation at the current moment; is the trajectory deviation at the previous moment; is the sampling period.

[0140] S202. Determine the current driving stage according to the deviation change rate; wherein the current driving stage is a forward driving stage or a reverse driving stage.

[0141] Specifically, when the deviation change rate is greater than or equal to zero, it is determined that the current driving stage is the forward driving stage, and when the deviation change rate is less than zero, it is determined that the current driving stage is the reverse driving stage.

[0142] S203. Determine a target PID control parameter corresponding to the current driving stage according to the current driving stage; wherein different driving stages correspond to different PID control parameters.

[0143] S204. Calculate an integral suppression parameter according to the trajectory deviation at the current moment; wherein the integral suppression parameter increases as the trajectory deviation decreases.

[0144] S205, calculating an integral control parameter according to the trajectory deviation, the target control amount at the previous moment, and the final control amount at the previous moment.

[0145] S206. Calculate the output of the integral controller according to the integral suppression parameter, the integral control parameter, and the integral gain in the target PID control parameter.

[0146] S207. Calculate the output of the proportional controller and the output of the differential controller according to the proportional gain and the differential gain in the target PID control parameters.

[0147] S208. Calculate the PID control output according to the output of the proportional controller, the output of the integral controller, and the output of the differential controller.

[0148] S209: Determine the target dead zone offset compensation currently used according to the PID control output, and compensate the PID control output according to the target dead zone offset compensation to obtain the target control amount at the current moment.

[0149] S210, using a saturation function to perform a limiting operation on the target control amount to obtain a final control amount at a current moment, and controlling the actuator according to the final control amount.

[0150] Specifically, the specific implementation process and implementation principle of steps S203 to S210 can be found in the description of the relevant technology, which will not be repeated here.

[0151] Furthermore, in order to verify the actual effect of the hydraulic excavator control method provided in the present application, a nonlinear model of the hydraulic system was established based on the analysis, and a simulation analysis of the electromechanical-hydraulic system of the excavator working device was performed based on the principle of nonlinear modeling.

[0152] Specifically, a control system is built in Simulink based on the control method provided in this application, and the optimized PID controller and the original PID controller are simulated.

[0153] Assume that the initial position of the hydraulic cylinder of the boom, dipper rod and bucket system is the middle position, the initial speed is 0, the pressure of the rodless chamber and the rod chamber is 30 bar and 32 bar respectively, and the initial position of the valve core is in the middle position. The load Fl is 15000N, 10000N, and 5000N respectively. Considering the trajectory interval output by the planning system and some special cases, the maximum stroke of the step response is set to 50mm.

[0154] The step response of each joint of the working device using the traditional PID controller is as follows Figure 4 As shown ( Figure 4 The figure is a schematic diagram of the step response of each joint when the hydraulic excavator is controlled by the traditional PID control method). In order to prevent the system from overshooting, the system error dynamics is designed as a critical damping situation. It can be seen that there is no overshoot in the step response at this time, but the dynamic response speed is insufficient. The maximum response time of the boom is about 2s, which is not suitable for trajectory tracking. Therefore, in order to improve the dynamic response performance of the system, the PID proportional integral control coefficient should be appropriately increased, but it may cause overshoot in a small range during the system response process.

[0155] Figure 5 This is a schematic diagram of the step response of each joint after improving the response speed, shown as an exemplary embodiment of the present application, wherein the red color is the response curve of the traditional PID controller, and the yellow color is the response curve of the hydraulic excavator control method provided by the present application. The two controllers use the same parameters in the simulation.

[0156] Reference Figure 5It can be seen that the system response is improved when using the traditional PID controller, but there are problems such as large overshoot and long response time. However, using the method provided by this application, the system overshoot is about 5%, and the adjustment time is short, only about 0.9s. The boom, dipper rod, and bucket have different response performances due to their different structural characteristic parameters.

[0157] Therefore, the method provided in the present application can overcome the integral saturation problem of the system, concentrate the integral weight at the position with smaller error and cut off the error integral when the output is saturated, thereby suppressing control overshoot while meeting the system responsiveness, and on the other hand, it can also greatly speed up the system's recovery to stability.

[0158] Figure 6 The following is a rendering of a sinusoidal signal tracking experiment based on the method provided by the present application. It can be seen that under the control strategy provided by the present application, the boom, the dipper arm, and the bucket can all achieve dynamic tracking of the trajectory, and there is a lag of about 0.28s in the tracking. Figure 7 This is a rendering of an excavation operation trajectory shown in an exemplary embodiment of the present application, refer to Figure 7 It can be seen that the method provided in this application is suitable for single actuator control of the hydraulic system of the excavation robot.

[0159] Corresponding to the aforementioned embodiment of a hydraulic excavator control method, the present application also provides an embodiment of a hydraulic excavator control device.

[0160] The embodiment of a hydraulic excavator control device of the present application can be applied to a hydraulic excavator. The device embodiment can be implemented by software, or by hardware or a combination of software and hardware. Taking software implementation as an example, as a device in a logical sense, the processor of the hydraulic excavator in which it is located reads the corresponding computer program instructions in the non-volatile memory into the memory and runs them. From the hardware level, if Figure 8 As shown, it is a hardware structure diagram of the hydraulic excavator where the hydraulic excavator control device of the present application is located, except Figure 8 In addition to the processor, memory, network interface, and non-volatile memory shown, the hydraulic excavator in which the device in the embodiment is located may also include other hardware according to the actual function of the hydraulic excavator, which will not be described in detail.

[0161] Fig. 9 This is a structural diagram of the first embodiment of the hydraulic excavator control device provided by this application. Fig. 9 The device provided in this embodiment is applied to a hydraulic excavator, and the device includes a control module 910, a parameter adjustment module 920 and an output compensation module 930; wherein,

[0162] The parameter adjustment module 920 is used to determine, for the actuator to be controlled, a target PID control parameter corresponding to the current driving stage according to the current driving stage in each sampling period; wherein the PID control parameters corresponding to different driving stages are different;

[0163] The parameter adjustment module 920 is used to calculate the integral suppression parameter according to the trajectory deviation at the current moment; wherein the integral suppression parameter increases as the trajectory deviation decreases;

[0164] The parameter adjustment module 920 is used to calculate the integral control parameter according to the trajectory deviation, the target control amount at the previous moment, and the final control amount at the previous moment;

[0165] The control module 910 is used to calculate the PID control output according to the integral suppression parameter, the integral control parameter, and the target PID control parameter;

[0166] The output compensation module 930 is used to determine the target dead zone offset compensation currently adopted according to the PID control output, and compensate the PID control output according to the target dead zone offset compensation to obtain the target control amount at the current moment;

[0167] The output compensation module 930 is further used to use a saturation function to perform a limiting operation on the target control amount to obtain a final control amount at a current moment, and control the actuator according to the final control amount.

[0168] The device of this embodiment can be used to perform Figure 1 The steps, specific implementation principles and implementation processes of the method embodiment shown are similar and will not be repeated here.

[0169] Please continue to refer to Figure 8 The present application also provides a hydraulic excavator, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of any one of the methods provided in the first aspect of the present application are implemented.

[0170] The present application also provides a computer-readable storage medium having a computer program stored thereon, and when the program is executed by a processor, the steps of any one of the methods provided in the present application are implemented.

[0171] The implementation process of the functions and effects of each unit in the above-mentioned device is specifically described in the implementation process of the corresponding steps in the above-mentioned method, and will not be repeated here.

[0172] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present application scheme. A person of ordinary skill in the art can understand and implement it without paying any creative work.

[0173] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A hydraulic excavator control method, characterized in that: The hydraulic excavator control method is applied to a hydraulic excavator, and the method comprises: For the actuator to be controlled, in each sampling period, according to the current driving stage, a target PID control parameter corresponding to the current driving stage is determined; wherein different driving stages correspond to different PID control parameters; Calculating an integral suppression parameter according to the trajectory deviation at the current moment; wherein the integral suppression parameter increases as the trajectory deviation decreases; Calculating an integral control parameter according to the trajectory deviation, the target control amount at the previous moment, and the final control amount at the previous moment; Calculating a PID control output according to the integral suppression parameter, the integral control parameter, and the target PID control parameter; Determine the target dead zone offset compensation currently used according to the PID control output, and compensate the PID control output according to the target dead zone offset compensation to obtain the target control amount at the current moment; The target control amount is limited by using a saturation function to obtain a final control amount at the current moment, and the actuator is controlled according to the final control amount.

2. The method according to claim 1, calculating the PID control output according to the integral suppression parameter, the integral control parameter, and the target PID control parameter, comprising: Calculating the output of the integral controller according to the integral suppression parameter, the integral control parameter, and the proportional gain and the integral gain in the target PID control parameter; Calculating the output of the proportional controller and the output of the differential controller according to the proportional coefficient and the differential coefficient in the target PID control parameter; The PID control output is calculated based on the output of the proportional controller, the output of the integral controller, and the output of the differential controller.

3. The method according to claim 2, characterized in that The step of calculating the output of the integral controller according to the integral suppression parameter, the integral control parameter, and the proportional gain and the integral gain in the target PID control parameter comprises: The output of the integral controller is calculated according to the following formula: ， Among them, the is the output of the integral controller; Said is the proportional gain; Said is the integral gain; Said is the integral control parameter; Said is the integral suppression parameter; Said is the trajectory deviation; Said is the sampling period.

4. The method according to claim 1, characterized in that: According to the trajectory deviation, an integral suppression parameter is calculated, including: The integral suppression parameter is calculated according to the following formula: ， Among them, the is the integral suppression parameter; Said is a preset coefficient less than 0; Said is the trajectory deviation.

5. The method according to claim 1, characterized in that The step of calculating the integral control parameter according to the trajectory deviation, the target control amount at the previous moment, and the final control amount at the previous moment includes: The integral control parameter is calculated according to the following formula: ， ， Among them, the is the integral control parameter; Said is the trajectory deviation; Said is the target control amount at the previous moment; Said is the final control amount at the previous moment.

6. The method according to claim 1, characterized in that The step of determining a target PID control parameter corresponding to the current driving stage according to the current driving stage includes: When the current driving stage is a forward driving stage, determining the target PID control parameters to be a first group of control parameters; When the current driving stage is a reverse driving stage, the target PID control parameters are determined to be a second group of control parameters; wherein each parameter in the first group of control parameters is greater than each parameter in the second group of control parameters.

7. The method according to claim 1, characterized in that Determining the target dead zone offset compensation currently used according to the PID control output includes: When the PID control output is greater than zero, the target dead zone offset compensation is determined to be a positive dead zone compensation amount; wherein the positive dead zone compensation amount is a critical control amount when the actuator generates a positive motion from an intermediate position when the control amount increases positively from 0; When the PID control output is equal to 0, determining the target dead zone offset compensation to be 0; When the PID control output is less than 0, the target dead zone offset compensation is determined to be a negative dead zone compensation; wherein the negative dead zone compensation is a critical current value when the actuator generates negative movement from the intermediate position when the control amount increases negatively from 0.

8. The method according to claim 1, characterized in that Before determining the target PID control parameter corresponding to the current driving stage according to the current driving stage, the method further includes: Calculating a deviation change rate according to the trajectory deviation; The current driving stage is determined according to the deviation change rate; when the deviation change rate is greater than or equal to zero, the current driving stage is determined to be the forward driving stage, and when the deviation change rate is less than zero, the current driving stage is determined to be the reverse driving stage.

9. A hydraulic excavator control device, characterized in that: The device is applied to a hydraulic excavator, and comprises a control module, a parameter adjustment module and an output compensation module; wherein, The parameter adjustment module is used to determine, for the actuator to be controlled, a target PID control parameter corresponding to the current driving stage according to the current driving stage in each sampling period; wherein the PID control parameters corresponding to different driving stages are different; The parameter adjustment module is used to calculate the integral suppression parameter according to the trajectory deviation at the current moment; wherein the integral suppression parameter increases as the trajectory deviation decreases; The parameter adjustment module is used to calculate the integral control parameter according to the trajectory deviation, the target control amount at the previous moment, and the final control amount at the previous moment; The control module is used to calculate the PID control output according to the integral suppression parameter, the integral control parameter, and the target PID control parameter; The output compensation module is used to determine the target dead zone offset compensation currently adopted according to the PID control output, and compensate the PID control output according to the target dead zone offset compensation to obtain the target control amount at the current moment; The output compensation module is further used to use a saturation function to perform a limiting operation on the target control amount to obtain a final control amount at the current moment, and control the actuator according to the final control amount.

10. A hydraulic excavator, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method according to any one of claims 1 to 8 when executing the program.

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