Method for controlling cantilever crane, high-altitude operation equipment and machine readable storage medium

Abstract

The invention discloses a method for controlling a boom, high-altitude operation equipment and a machine readable storage medium, and belongs to the technical field of engineering machinery, the method comprises the steps that the target displacement amount of an executing mechanism of the boom in the next control period is obtained, and the executing mechanism of the boom comprises at least one of a rotary motor, a telescopic oil cylinder and a variable-amplitude oil cylinder; according to the target displacement, a target control current of the execution mechanism is determined based on a pre-constructed prediction model and a preset constraint condition, and the prediction model is used for predicting the corresponding displacement according to the input control current; and outputting the target control current of the execution mechanism to the execution mechanism so as to control the arm support to act. The control quantity of each execution mechanism of the boom can be determined by adopting the model prediction control method on the basis of the pre-constructed prediction model in combination with the preset constraint condition, so that the control error can be reduced, and the control stability can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of aerial machinery, and in particular to a method for controlling a boom, aerial work equipment and a machine-readable storage medium. Background Art

[0002] At present, there are two main methods for tracking the trajectory of the boom end point. One is closed-loop collaborative control, which uses the integrated sensor in the hydraulic system to track the trajectory; the other is a PID controller that includes feedforward, static deflection compensation, etc. However, since the control of the boom end point position involves multi-axis linkage control such as turntable rotation, boom amplitude change and boom extension, there is a strong coupling between the axes, and oscillation problems are prone to occur during the control process. The above control methods cannot avoid the control oscillation problem, and the boom has poor stability. Therefore, the boom end control method used in the prior art has the problem of poor stability. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a method for controlling a boom, aerial work equipment, and machine-readable storage medium, so as to solve the problem of poor stability of the boom end control method adopted in the prior art.

[0004] In order to achieve the above-mentioned object, a first aspect of an embodiment of the present application provides a method for controlling a boom, the method comprising:

[0005] Obtaining a target displacement of an actuator of the boom in the next control cycle, wherein the actuator of the boom includes at least one of a slewing motor, a telescopic cylinder, and a luffing cylinder;

[0006] According to the target displacement, based on a pre-built prediction model and preset constraints, a target control current of the actuator is determined, wherein the prediction model is used to predict the corresponding displacement according to the input control current;

[0007] The target control current of the actuator is output to the actuator to control the boom movement.

[0008] In an embodiment of the present application, according to the target displacement, based on a pre-built prediction model and preset constraints, the target control current of the actuator is determined, including: inputting the preset control current of the actuator into the prediction model to obtain the corresponding predicted displacement; determining the displacement error of the actuator according to the predicted displacement and the target displacement; adjusting the preset control current input into the prediction model according to the displacement error until the absolute value of the displacement error of the actuator is less than or equal to the corresponding preset error, and the corresponding system parameters meet the preset constraints, wherein the system parameters include the preset control current of the actuator, the total flow of the hydraulic system of the boom, the length of the boom, the pitch angle of the boom, and the slew angle of the boom; and determining the adjusted preset control current as the target control current.

[0009] In the embodiment of the present application, the preset constraint conditions include: the preset control current of the actuator is greater than or equal to the corresponding set current; the total flow of the hydraulic system of the boom is less than the preset flow;

[0010] The length of the boom is within a preset length range; the pitch angle of the boom is within a first preset angle range; and the rotation angle of the boom is within a second preset angle range.

[0011] In an embodiment of the present application, the method also includes: obtaining the current control current of the arm's actuator; determining the current change of the actuator based on the current control current and the preset control current; based on a pre-constructed objective function, determining the objective function value corresponding to the preset control current according to the displacement error and current change of the actuator; adjusting the preset control current until the objective function value is less than or equal to the preset function value.

[0012] In an embodiment of the present application, a preset control current of the actuator is input into a prediction model to obtain a corresponding predicted displacement, including: based on a pre-constructed mapping relationship between the control current of the actuator and the proportional valve flow, determining the corresponding proportional valve flow according to the preset control current; based on a pre-constructed mapping relationship between the proportional valve flow and the balancing valve flow of the actuator, determining the corresponding balancing valve flow according to the proportional valve flow; based on a pre-constructed mapping relationship between the balancing valve flow and the operating speed of the actuator, determining the corresponding operating speed according to the balancing valve flow; based on a pre-constructed mapping relationship between the operating speed and the displacement of the actuator, determining the predicted displacement of the actuator according to the operating speed.

[0013] In an embodiment of the present application, the method also includes: obtaining the actual displacement of the actuator after the arm moves; based on the prediction model, determining the target predicted displacement of the actuator according to the target control current of the actuator; determining the prediction error of the actuator according to the actual displacement and the target predicted displacement; and correcting the prediction model according to the prediction error feedback of the actuator.

[0014] In an embodiment of the present application, the prediction model is corrected based on the prediction error feedback of the actuator, including: correcting the displacement output by the prediction model based on the prediction error and a preset correction coefficient to obtain a corrected displacement.

[0015] In an embodiment of the present application, obtaining the target displacement of the actuator of the arm in the next control cycle includes: obtaining the current posture data of the arm and the target posture data of the next control cycle; and determining the target displacement of the actuator of the arm based on the current posture data and the target posture data.

[0016] A second aspect of an embodiment of the present application provides an aerial work equipment, which uses the above-mentioned method for controlling a boom to control the boom.

[0017] A third aspect of an embodiment of the present application provides a machine-readable storage medium, on which a program or instruction is stored. When the program or instruction is executed by a processor, the above-mentioned method for controlling an arm is implemented.

[0018] The above technical solution obtains the target displacement of the actuator of the boom in the next control cycle, wherein the actuator of the boom includes at least one of a slewing motor, a telescopic cylinder and a luffing cylinder, and then determines the target control current of the actuator according to the target displacement based on a pre-built prediction model and preset constraints, wherein the prediction model is used to predict the corresponding displacement according to the input control current, and finally outputs the target control current of the actuator to the actuator to control the action of the boom. The present application can adopt a model predictive control method based on a pre-built prediction model, combined with preset constraints, to determine the control amount of each actuator of the boom, which is conducive to reducing control errors and improving control stability.

[0019] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. In the accompanying drawings:

[0021] Figure 1 A schematic flow chart of a method for controlling a boom provided in an embodiment of the present application;

[0022] Figure 2 A structural block diagram of a boom end trajectory control device provided in a specific embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the specific implementation methods described herein are only used to illustrate and explain the embodiments of the present application, and are not used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0024] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0025] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0026] Figure 1 A flow chart of a method for controlling a boom provided in an embodiment of the present application. Figure 1 As shown, an embodiment of the present application provides a method for controlling an arm, which is described by taking the method applied to a processor as an example. The method may include the following steps.

[0027] Step S101, obtaining a target displacement of an actuator of the boom in the next control cycle, wherein the actuator of the boom includes at least one of a slewing motor, a telescopic cylinder and a luffing cylinder.

[0028] Step S102, determining a target control current of the actuator according to the target displacement based on a pre-built prediction model and preset constraints, wherein the prediction model is used to predict the corresponding displacement according to the input control current.

[0029] Step S103, outputting the target control current of the actuator to the actuator to control the boom movement.

[0030] Specifically, the actuators for controlling the movement of the end of the boom mainly include a slewing motor for controlling the rotation of the boom, a telescopic cylinder for controlling the extension of each arm section of the boom, and a variable-length cylinder for controlling the amplitude change of the boom. It can be understood that the control process of controlling the end of the boom to reach the target position from the current position can be decomposed into multiple control cycles, and the processor can obtain the target displacement of the actuator corresponding to the movement of the end of the boom from the position of the current control cycle to the position of the next control cycle. In one example, the target displacement can include the slewing displacement of the slewing motor of the boom, the cylinder length change of each telescopic cylinder on the boom, and the cylinder length change of each variable-length cylinder on the boom.

[0031] It can be understood that the traditional boom control method is usually a PID control method. Considering that the problem of boom end trajectory tracking is essentially a multi-axis linkage problem of the whole vehicle, there are at least three-axis linkages of turntable rotation, boom amplitude change and boom lifting. The coupling between the control loops is strong, which is easy to produce control oscillation and jitter, and the parameters are not easy to adjust. In order to ensure the stability of the boom control process, the embodiment of the present application adopts a model predictive control strategy to control the boom. Specifically, the target displacement of the boom's actuator is used as a reference trajectory. According to the pre-constructed prediction model in the control system, combined with the preset constraints, rolling optimization is implemented in the corresponding control cycle, and the control amount is continuously optimized in a limited step length to determine the target control current corresponding to the boom's actuator. Among them, the prediction model is used to predict the corresponding displacement according to the input control current. In one example, the prediction model is constructed according to the actual electrical, hydraulic and structural relationship of the whole vehicle, which can be the mathematical relationship between the solenoid valve control current of the actuator and the displacement of the actuator. The preset constraints are set based on the electromechanical and hydraulic characteristics of the actual system. In this way, compared with PID control, the predictive control method adopted in the embodiment of the present application comprehensively considers how to make the control error smaller and the control smoother when each control mechanism is given to control the current, so as to greatly reduce the control difficulty by giving the optimal control solution from the current control cycle to the next control cycle.

[0032] Finally, the controller can send the target control current of each actuator to the corresponding solenoid valve to adjust the size of the hydraulic valve opening and control the boom movement so that the end of the boom moves from the position of the current cycle to the corresponding position of the next cycle.

[0033] The above technical solution obtains the target displacement of the actuator of the boom in the next control cycle, wherein the actuator of the boom includes at least one of a slewing motor, a telescopic cylinder and a luffing cylinder, and then determines the target control current of the actuator according to the target displacement based on a pre-built prediction model and preset constraints, wherein the prediction model is used to predict the corresponding displacement according to the input control current, and finally outputs the target control current of the actuator to the actuator to control the action of the boom. The present application can adopt a model predictive control method based on a pre-built prediction model, combined with preset constraints, to determine the control amount of each actuator of the boom, which is conducive to reducing control errors and improving control stability.

[0034] In an embodiment of the present application, obtaining the target displacement of the actuator of the arm in the next control cycle includes: obtaining the current posture data of the arm and the target posture data of the next control cycle; and determining the target displacement of the actuator of the arm based on the current posture data and the target posture data.

[0035] It can be understood that the control process of controlling the end of the boom to reach the target position from the current position can be decomposed into multiple control cycles. The processor can determine the target displacement of the actuator corresponding to the movement of the end of the boom from the position of the current control cycle to the position of the next control cycle based on the posture data of the boom corresponding to the two adjacent cycles. Specifically, the current posture data of the boom in the current control cycle and the target posture data of the boom in the next control cycle are obtained, and the current position of the end of the boom is determined according to the current posture data based on the geometric structure relationship of the boom, and the target position of the end of the boom in the next cycle is determined according to the target posture data. Based on the current position and the next position, the target displacement of each actuator is obtained by converting the trigonometric function relationship. Among them, the posture data of the boom can be collected by multiple sensors, such as ultrasonic sensors, millimeter wave radar sensors, rope sensors, boom inclination sensors and rotary encoders, etc. The real-time posture of the boom is obtained by comprehensive calculation based on the data collected by each sensor. In this way, a data basis is provided for subsequent calculations.

[0036] In an embodiment of the present application, according to the target displacement, based on a pre-built prediction model and preset constraints, the target control current of the actuator is determined, including: inputting the preset control current of the actuator into the prediction model to obtain the corresponding predicted displacement; determining the displacement error of the actuator according to the predicted displacement and the target displacement; adjusting the preset control current input into the prediction model according to the displacement error until the absolute value of the displacement error of the actuator is less than or equal to the corresponding preset error, and the corresponding system parameters meet the preset constraints, wherein the system parameters include the preset control current of the actuator, the total flow of the hydraulic system of the boom, the length of the boom, the pitch angle of the boom, and the slew angle of the boom; and determining the adjusted preset control current as the target control current.

[0037] It can be understood that the preset control current can be set according to the actual situation of the whole vehicle. Preferably, the preset control current of the actuator can be the execution current of the current control cycle. The present application adopts the inverse operation method, based on the prediction model and the preset constraints, to solve the target control current of the actuator according to the target displacement of the actuator. Specifically, after the preset control current is input into the prediction model, the predicted displacement output by the model can be obtained, and then the difference between the predicted displacement and the target displacement is determined to obtain the displacement error of the actuator under the current preset control current. At the same time, the corresponding system parameters under the predicted control current are determined according to the intermediate quantity generated by the prediction model. The system parameters include the preset control current of the actuator, the total flow of the hydraulic system of the boom, the length of the boom, the pitch angle of the boom, and the rotation angle of the boom. Further, the absolute value of the displacement error is compared with the size relationship of the preset error, and at the same time, it is judged whether the system parameters meet the preset constraints.

[0038] In one example, when the absolute value of the displacement error is greater than the preset error, and / or the system parameters do not meet the constraints, it means that the current preset control current cannot guarantee the smoothness of the arm control. At this time, the preset control current input into the prediction model can be adjusted according to the displacement error until the absolute value of the displacement error of the actuator is less than or equal to the corresponding preset error, and the corresponding system parameters meet the preset constraints.

[0039] In another example, when the absolute value of the displacement error is less than or equal to the corresponding preset error and the corresponding system parameter satisfies the preset constraint condition, the adjusted preset control current corresponding to the moment is determined as the target control current. In this way, the target control current corresponding to each actuator is determined by performing a quadratic programming solution based on the prediction function and the preset constraint condition, which is conducive to providing the stability of the subsequent boom control.

[0040] In an embodiment of the present application, the preset constraints include: the preset control current of the actuator is greater than or equal to the corresponding set current; the total flow of the hydraulic system of the boom is less than the preset flow; the length of the boom is within a preset length range; the pitch angle of the boom is within a first preset angle range; and the rotation angle of the boom is within a second preset angle range.

[0041] Specifically, the embodiments of the present application design constraints in combination with the range of change of the control current, the maximum flow rate that can be provided by the hydraulic system of the whole vehicle, and the limit conditions of each mechanical component. The minimum value of the boom retraction current is particularly special in the control current. When the boom inclination angle is high, the extension length is long, and the load is heavy, it is necessary to consider appropriately increasing the starting value of the retraction current to avoid strong nonlinear sections and maintain stable control performance. In addition, the maximum flow rate that can be provided by the hydraulic pressure is added to the constraint condition, taking into account the load-sensitive characteristics of the hydraulic pressure. When the maximum flow rate is not enough to supply each compound action, it is distributed according to the load of each hydraulic component. At this time, the electro-hydraulic characteristics will have a lot of differences from the calibration curve. During the control process, the required total flow rate should be avoided as much as possible to avoid exceeding u; the maximum value can be provided. In an example, taking the boom actuator including a slewing motor, a telescopic cylinder, and a boom cylinder as an example, the preset constraint condition can be expressed as:

[0042]

[0043] Among them, U min =[u 1min ,u 2min ,u 3min ] is the set current of each actuator, the set current

[0044] ″′

[0045] is the minimum starting current (per thousandth) of the corresponding circuit of each actuator; f1(k), f2(k) and f3(k) are the flow rates of the corresponding circuits of each actuator, and their sum is the total flow rate of the hydraulic system. max is the preset flow, i.e. the maximum flow that the hydraulic system can provide; [L 1min ,L 1max ] is the preset length range, L 1min is the minimum length of the boom, L 1max is the maximum length of the boom; [θ 1min ,θ 1max ] is the first preset angle range, θ 1min is the minimum pitch angle of the boom, θ 1max is the maximum pitch angle of the boom; [θ 2min ,θ 2max ] is the second preset angle range, θ 2min is the minimum value of the boom rotation angle, θ 2max It is the maximum value of the arm rotation angle.

[0046] In this way, the constraints are designed in combination with the variation range of the control current, the maximum flow rate that the vehicle hydraulic system can provide, and the limit conditions of each mechanical component. For example, the limitation of the maximum flow rate that the system can provide is added to the constraints to avoid the problem of insufficient flow during the control process and the electro-hydraulic characteristic deviation caused by the load-sensitive characteristics of the hydraulic system.

[0047] In an embodiment of the present application, the method further includes: obtaining a current control current of an actuator of the arm; determining a current change of the actuator according to the current control current and a preset control current; determining a target function value corresponding to the preset control current according to a displacement error and a current change of the actuator based on a pre-constructed target function; adjusting the preset control current until the target function value is less than or equal to the preset function value;

[0048] It can be understood that the preset function value can be set according to the actual operation of the vehicle or user needs. In order to further improve the stability of the boom control, the embodiment of the present application can design the objective function according to the control error minimization requirements and the electrical, hydraulic and mechanical characteristics of the actual vehicle, and perform quadratic programming solution in combination with the prediction model, preset constraints and objective function to obtain the optimal control sequence that minimizes the objective function and satisfies all constraints at the same time, that is, the target control flow of each actuator, and send the control sequence to the vehicle through the controller to achieve smooth control of the boom.

[0049] Specifically, the objective function is mainly to minimize the control error, that is, the displacement error. At the same time, the objective function also needs to take into account the change amplitude of the control increment, that is, the current change of the actuator. The design here is mainly carried out from three aspects, aiming to maintain the comfort of the driving experience, maintain the system energy consumption at a normal or low level, and reduce the impact damage to the hydraulic and mechanical systems of the whole vehicle.

[0050] In an example, taking the boom actuator including a slewing motor, a telescopic cylinder, and a luffing cylinder as an example, the objective function can satisfy the following formula:

[0051]

[0052] in, represents the second norm of the displacement error, ‖ΔU(k+i|k)‖ represents the second norm of the current change, Ny is the prediction time domain, and Nu is the control time domain. J is the objective function value, Q is the preset displacement error weight matrix, and R is the preset current change weight matrix. is the displacement error of the actuator, is the displacement output by the prediction model, Y r (k) is the target displacement, and ΔU(k) ​​is the current change of the actuator.

[0053] In this way, the current change of the actuator is introduced into the objective function, and control oscillation, commutation shock, energy loss, etc. are considered and added to the construction of the control increment weight matrix. At the same time, the control oscillation and shock as well as the problem that the system may have a small energy depletion during the control process are considered.

[0054] In an embodiment of the present application, a preset control current of the actuator is input into a prediction model to obtain a corresponding predicted displacement, including: based on a pre-constructed mapping relationship between the control current of the actuator and the proportional valve flow, determining the corresponding proportional valve flow according to the preset control current; based on a pre-constructed mapping relationship between the proportional valve flow and the balancing valve flow of the actuator, determining the corresponding balancing valve flow according to the proportional valve flow; based on a pre-constructed mapping relationship between the balancing valve flow and the operating speed of the actuator, determining the corresponding operating speed according to the balancing valve flow; based on a pre-constructed mapping relationship between the operating speed and the displacement of the actuator, determining the predicted displacement of the actuator according to the operating speed.

[0055] Specifically, the mapping relationship between the control current and the proportional valve flow of the pre-constructed actuator is the basic electro-hydraulic characteristic relationship of the vehicle control system. In one example, the current and flow relationship curves of the slewing and main arm amplitude (extension) proportional valves can be linearly fitted based on the existing hydraulic test bench test data to obtain the mapping relationship between the control current and the proportional valve flow of the actuator. The mapping relationship between the proportional valve flow and the balance valve flow of the actuator is the nonlinear characteristic of the electro-hydraulic system. The actual vehicle test shows that when the boom amplitude is changed to more than 60 degrees and extended to close to the boom extension limit and the control current is small, the relationship between the current and the flow shows a strong nonlinearity; after studying the composition of the hydraulic system, it is analyzed that the nonlinearity mainly comes from the switching characteristics of the balance valve under negative load conditions. The characteristics are described by using a second-order discrete z-domain transfer function to obtain the mapping relationship between the proportional valve flow and the balance valve flow of the actuator. The mapping relationship between the balance valve flow and the operating speed of the actuator is the conversion relationship between the balance valve hydraulic flow and the cylinder (motor) movement speed; in an example, the movement speed of the hydraulic element can be calculated from the motor displacement of the rotary motor, the transmission ratio of the rotary mechanism, the cylinder diameter and rod diameter of the telescopic (variable amplitude) cylinder, etc., and the multiplication of the speed with the duration of the control cycle is the motor / cylinder displacement increment value at the current moment, thereby obtaining the mapping relationship between the operating speed and displacement of the actuator.

[0056] In this way, the prediction model is equipped with a fitting link for the nonlinear characteristics of the hydraulic system balance valve in order to address the nonlinear posture of the boom's pitch angle and extension length. This enhances the prediction model's ability to describe various system conditions and provides a solution to the control oscillation problem of ordinary PID control systems under extreme scenarios.

[0057] In an embodiment of the present application, the method also includes: obtaining the actual displacement of the actuator after the arm moves; based on the prediction model, determining the target predicted displacement of the actuator according to the target control current of the actuator; determining the prediction error of the actuator according to the actual displacement and the target predicted displacement; and correcting the prediction model according to the prediction error feedback of the actuator.

[0058] Specifically, the actual displacement of the actuator after the arm action can be obtained through the vehicle's long angle sensor, rotary encoder, etc. At the same time, according to the final control current, the target predicted displacement of the actuator can be determined through the prediction model. Then, according to the difference between the actual displacement and the target predicted displacement, the prediction error of the actuator can be determined, and finally, the prediction model can be corrected according to the prediction error feedback of the actuator. In this way, according to the actual displacement of the actuator, the prediction model can be calibrated in the next control cycle, which can achieve the optimization of the prediction model and continuously improve the accuracy of the prediction model.

[0059] In an embodiment of the present application, the prediction model is corrected based on the prediction error feedback of the actuator, including: correcting the displacement output by the prediction model based on the prediction error and a preset correction coefficient to obtain a corrected displacement.

[0060] Specifically, the preset correction coefficient can be set after the experiment. According to the preset error and the preset correction coefficient, the output value of the prediction model can be corrected in the next control cycle to obtain the corrected displacement. In this way, periodically performing feedback optimization on the prediction model is conducive to improving the accuracy of the prediction model.

[0061] Figure 2 This is a structural block diagram of a boom end trajectory control device provided in a specific embodiment of the present application. Figure 2 As shown, the tracking control of the terminal trajectory is achieved through various hardware devices loaded on the vehicle.

[0062] Hardware devices are mainly divided into four categories according to their functions, including:

[0063] 1. Operating handle and dial switch. Used to transmit the user's operating instructions to the device, switch the normal working mode and the terminal trajectory tracking control mode, switch the trajectory tracking direction, etc.

[0064] 2. Sensors. These include ultrasonic sensors, millimeter-wave radars, boom tilt sensors, rope sensors, and rotary encoders, which are used to obtain the current vehicle posture, the motion position of the boom end, etc. Specifically, the ultrasonic sensor can be fixed on the outer surface of the work platform by adding fixed tooling, and the millimeter-wave radar can be installed on the side close to the boom end. The two types of sensors monitor and record the relative position of the platform and the target in real time, making it easier for the control system to adjust the set trajectory in a timely manner.

[0065] 3. The vehicle controller is used to send a control current signal to the hydraulic solenoid valve according to the received posture, position information, user instructions, etc. according to the designed control method.

[0066] 4. Hydraulic solenoid valve, used to respond to the control signal sent by the controller, drive the turntable rotation mechanism, boom luffing mechanism, and boom telescopic mechanism to act according to the specified signal.

[0067] In a specific embodiment of the present application, the operation process of the control system when performing boom end trajectory tracking includes the following steps:

[0068] Step 1: The operator turns the switch to turn on the end trajectory tracking function, sets the end position of the boom at the initial rest as the starting coordinate P0, and determines the trajectory tracking direction (up, down, left, and right) through the operating handle.

[0069] Step 2: The planning layer plans the target boom end position P for the current control cycle k based on the real-time posture of the vehicle obtained by the planning layer based on the relative position between the vehicle and the target wall obtained by the ultrasonic sensor, millimeter wave radar and other ranging sensors, as well as the measurement data of the rope sensor, boom inclination sensor and rotary encoder. r (k), and use the information such as arm length, inclination angle, rotation angle, etc. to convert it into the target telescopic cylinder displacement y under this cycle through trigonometric function relationship 1r (k) Displacement of the variable amplitude cylinder y 2r (k), rotary motor displacement y 3r (k), that is, Y r (k) = [y 1r (k)y 2r (k)y 3r (k)] T .

[0070] Step 3: According to the prediction model designed in the control system (the mathematical relationship between the solenoid valve control current and the displacement of the hydraulic actuator), the constraints related to the actual system electromechanical and hydraulic characteristics, and the objective function, a rolling optimization is implemented in the kth control cycle, the control quantity (in this scheme, the input current of the corresponding cylinder and motor solenoid valve) is continuously optimized in a finite step length, and the predicted performance of the hydraulic actuator displacement under the control quantity is calculated. Select the optimal control current U(k)=[u1(k)u2(k)u3(k)] that minimizes the control error and satisfies all constraints. T , if it cannot be fully satisfied, the current suboptimal solution will also be selected.

[0071] Step 4: The controller sends the optimal control current to the corresponding solenoid valve, adjusts the opening of the hydraulic valve port, obtains the real-time data of the sensor from the bus, and calculates and converts the actual telescopic (amplitude) cylinder extension and rotation angle of the system to obtain Y(k) = [y1(k)y2(k)y3(k)] T .

[0072] Step 5: Calculate the output value Y(k) of the hydraulic actuator of the real system and the output value of the prediction model The difference is compensated in the update of the state variables of the model in the next control cycle to correct the model prediction error caused by model mismatch or environmental disturbance.

[0073] Step 6: If the operator does not issue a termination command for the end trajectory tracking, continue to repeat from step 2. If a termination command is issued, the control process ends.

[0074] In summary, this solution introduces a strong nonlinear link caused by hydraulic components into the prediction model. The overall control strategy has a strong ability to cope with nonlinearity, which can solve the problem of poor driving experience caused by PID control jitter under more extreme working conditions; the control oscillation and impact, and the minimization of energy loss are considered in the objective function, and the composition of the control increment weight matrix is ​​optimized. While maintaining stable control, the control sequence with low energy consumption is preferred; the constraint condition adds the maximum flow rate that the system can provide, and the range of the control sequence is controlled within the normal capacity boundary of the system. If you want to achieve the same effect using a PID control loop, you need to compile a large number of complex programs after the main PID module to supplement the limitations of the PID control itself. Therefore, compared with traditional PID control, the control difficulty of the embodiment of the present application is greatly reduced, and the stability of the boom control is higher.

[0075] An embodiment of the present application also provides an aerial work equipment configured to execute the method for controlling the boom in the above-mentioned embodiment.

[0076] An embodiment of the present application also provides a machine-readable storage medium, on which a program or instruction is stored. When the program or instruction is executed by a processor, the method for controlling the boom in the above-mentioned embodiment is implemented.

[0077] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0078] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems) and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0079] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0080] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0081] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0082] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0083] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0084] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0085] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for controlling a boom, characterized in that: The method comprises: Obtaining a target displacement of an actuator of the boom in a next control cycle, wherein the actuator of the boom includes at least one of a slewing motor, a telescopic cylinder, and a luffing cylinder; According to the target displacement, based on a pre-built prediction model and preset constraints, a target control current of the actuator is determined, wherein the prediction model is used to predict the corresponding displacement according to the input control current; The target control current of the actuator is output to the actuator to control the action of the boom.

2. The method according to claim 1, characterized in that Determining the target control current of the actuator according to the target displacement, based on a pre-built prediction model and preset constraints, includes: Inputting the preset control current of the actuator into the prediction model to obtain the corresponding predicted displacement; Determining a displacement error of the actuator according to the predicted displacement and the target displacement; According to the displacement error, the preset control current input to the prediction model is adjusted until the absolute value of the displacement error of the actuator is less than or equal to the corresponding preset error, and the corresponding system parameters meet the preset constraint conditions, wherein the system parameters include the preset control current of the actuator, the total flow of the hydraulic system of the boom, the length of the boom, the pitch angle of the boom, and the rotation angle of the boom; The adjusted preset control current is determined as the target control current.

3. The method according to claim 2, characterized in that The preset constraints include: The preset control current of the actuator is greater than or equal to the corresponding set current; The total flow of the hydraulic system of the boom is less than the preset flow; The length of the arm is within a preset length range; The pitch angle of the boom is within a first preset angle range; and The rotation angle of the arm is within a second preset angle range.

4. The method according to claim 2, characterized in that: The method further comprises: Obtaining a current control current of an actuator of the arm; Determining a current change amount of the actuator according to the current control current and the preset control current; Based on the pre-constructed objective function, the objective function value corresponding to the preset control current is determined according to the displacement error and the current change of the actuator; The preset control current is adjusted until the objective function value is less than or equal to the preset function value.

5. The method according to claim 2, characterized in that: The step of inputting the preset control current of the actuator into the prediction model to obtain the corresponding predicted displacement comprises: Based on the pre-built mapping relationship between the control current of the actuator and the proportional valve flow rate, determining the corresponding proportional valve flow rate according to the preset control current; Based on the pre-built mapping relationship between the proportional valve flow and the balancing valve flow of the actuator, determining the corresponding balancing valve flow according to the proportional valve flow; Based on the pre-built mapping relationship between the balancing valve flow rate and the operating speed of the actuator, determining the corresponding operating speed according to the balancing valve flow rate; Based on a pre-constructed mapping relationship between the operating speed and the displacement of the actuator, the predicted displacement of the actuator is determined according to the operating speed.

6. The method according to claim 1, characterized in that The method further comprises: Obtaining the actual displacement of the actuator after the boom moves; Based on the prediction model, determining a target predicted displacement of the actuator according to a target control current of the actuator; Determining a prediction error of the actuator according to the actual displacement and the target predicted displacement; The prediction model is corrected according to the prediction error feedback of the actuator.

7. The method according to claim 6, characterized in that The step of correcting the prediction model based on the prediction error feedback of the actuator includes: The displacement output by the prediction model is corrected according to the prediction error and a preset correction coefficient to obtain a corrected displacement.

8. The method according to claim 1, characterized in that The obtaining of the target displacement of the actuator of the boom in the next control cycle includes: Acquiring current posture data of the boom and target posture data of the next control cycle; The target displacement of the actuator of the boom is determined according to the current posture data and the target posture data.

9. A high-altitude working equipment, characterized in that: The boom is controlled by using the method for controlling the boom according to any one of claims 1 to 8.

10. A machine-readable storage medium storing a program or an instruction, characterized in that: When the program or the instruction is executed by a processor, the method for controlling a boom according to any one of claims 1 to 8 is implemented.

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