End effector control method, mechanical equipment, electronic equipment and storage medium

Abstract

The invention discloses a control method of an end effector, mechanical equipment, electronic equipment and a storage medium, and belongs to the technical field of automatic control technologies. The control method of the end effector comprises the steps that the actual output force collected by the force sensor is obtained; the pressure, collected by the pressure sensor, in the pipeline is obtained, and inter-relay force is calculated according to the pressure in the pipeline; determining an output error according to a difference value between the actual output force and a target force, and setting weight information according to the output error; adjusting parameters are determined based on the weight information, the actual output force, the inter-force and the target force; and the pressure adjusting device is controlled to work according to the adjusting parameters, so that the end effector works according to the target force. According to the invention, the end effector can be accurately controlled to output stable force.

Description

Technical Field

[0001] The present application relates to the field of automatic control technologies, and particularly relates to a control method for an end effector, a mechanical device, an electronic device, and a storage medium. Background Art

[0002] Mechanical devices such as numerically controlled machine tools and stamping equipment are equipped with end effectors. An end effector suitable for force-stable control machining can perform surface strengthening treatment on the surface of a workpiece according to a set force.

[0003] During the process of the end effector performing surface strengthening on the workpiece, it is necessary for the end effector to output a stable acting force to ensure the machining quality. In related technologies, a force sensor is usually arranged on the surface where the end effector contacts the load, and the output force of the end effector is adjusted according to the measured value of the force sensor. However, the above adjustment method is easily affected by the superposition of pressure transmission delay and load mutation, and thus an overshoot phenomenon occurs; moreover, the measured value of the above force sensor is easily interfered, and the control accuracy is low.

[0004] Therefore, how to accurately control the end effector to output a stable force is a technical problem that those skilled in the art need to solve currently. Summary of the Invention

[0005] The purpose of the present application is to provide a control method for an end effector, a mechanical device, an electronic device, and a storage medium, which can accurately control the end effector to output a stable force.

[0006] To solve the above technical problem, the present application provides a control method for an end effector, which is applied to a controller of a mechanical device. The control method for the end effector includes:

[0007] Step 1: Obtain the actual output force collected by the force sensor; obtain the pressure in the pipeline collected by the pressure sensor, and calculate an indirect force according to the pressure in the pipeline; wherein, the indirect force is the acting force of the fluid on the end effector;

[0008] Step 2: Determine an output error according to the difference between the actual output force and the target force, and set weight information according to the output error; wherein, the weight information includes a first weight corresponding to the force sensor and a second weight corresponding to the pressure sensor;

[0009] Step 3: Determine an adjustment parameter based on the weight information, the actual output force, the indirect force, and the target force;

[0010] Step 4: Control the pressure regulating device to work according to the adjustment parameter, so that the end effector operates according to the target force.

[0011] Optionally, determine an output error based on the difference between the actual output force and the target force, and set weight information according to the output error, including:

[0012] Set the absolute value of the difference between the actual output force and the target force as the output error;

[0013] If the output error is less than or equal to a first threshold, set the first weight to a first fixed value and the second weight to a second fixed value;

[0014] If the output error is greater than the first threshold and less than a second threshold, set the first weight and the second weight according to the output error; wherein, the first weight is negatively correlated with the output error, and the second weight is positively correlated with the output error;

[0015] If the output error is greater than the second threshold, set the first weight to a third fixed value and the second weight to a fourth fixed value; wherein, the first fixed value is greater than the third fixed value, and the second fixed value is less than the fourth fixed value.

[0016] Optionally, determine an adjustment parameter based on the weight information, the actual output force, the indirect force, and the target force, including:

[0017] Take the difference between the target force and the actual output force as a first error;

[0018] Take the difference between the target force and the indirect force as a second error;

[0019] Perform weighted calculation on the first error and the second error based on the weight information to obtain a proportional term;

[0020] Perform differential calculation on the first error to obtain a differential term;

[0021] Determine the adjustment parameter according to the proportional term and the differential term.

[0022] Optionally, the calculation formula for the proportional term P is: , represents the proportional gain, represents the first weight, represents the target force, represents the actual output force, represents the second weight, represents the indirect force;

[0023] The calculation formula for the differential term D is: , represents the differential gain, represents the differential of the first error, and dt represents the differential with respect to time;

[0024] the adjustment parameter 。

[0025] Optionally, before setting the weight information according to the output error, it further includes:

[0026] setting the absolute value of the difference between the actual output force and the indirect force as the system residual;

[0027] judging whether the duration for which the system residual continuously exceeds a third threshold is greater than a first target duration;

[0028] if so, it is determined that a fault exists, and the control process of the end effector in the fault mode is started;

[0029] if not, the step of setting the weight information according to the output error is entered.

[0030] Optionally, the control process of the end effector in the fault mode includes:

[0031] determining a temporary adjustment parameter according to the actual output force or the indirect force, and controlling the pressure regulating device to work according to the temporary adjustment parameter;

[0032] if the duration for which the system residual continuously is less than or equal to the fourth threshold is greater than a second target duration, the step of setting the weight information according to the output error is entered; wherein, the third threshold is greater than or equal to the fourth threshold.

[0033] Optionally, the end effector is an actuator with a built-in hydraulic cylinder;

[0034] Correspondingly, calculating the indirect force according to the pressure in the pipeline includes:

[0035] calculating the indirect force according to the effective area of the hydraulic cylinder and the pressure in the pipeline.

[0036] This application also provides a mechanical device, which includes a controller, a pressure regulating device, a pressure sensor, an end effector and a force sensor. The end effector is an actuator driven by a fluid. The pressure regulating device is connected to the end effector through a preset pipeline. The pressure regulating device is used to regulate the pressure of the fluid in the preset pipeline. The pressure sensor is arranged in the preset pipeline, and the force sensor is arranged at the contact surface between the end effector and the load;

[0037] When the controller works, the operations performed include:

[0038] Step 1: Obtain the actual output force collected by the force sensor; obtain the pressure inside the pipeline collected by the pressure sensor, and calculate the indirect force according to the pressure inside the pipeline; wherein, the indirect force is the acting force of the fluid on the end effector.

[0039] Step 2: Determine the output error according to the difference between the actual output force and the target force, and set the weight information according to the output error; wherein, the weight information includes a first weight corresponding to the force sensor and a second weight corresponding to the pressure sensor.

[0040] Step 3: Determine the adjustment parameter based on the weight information, the actual output force, the indirect force, and the target force.

[0041] Step 4: Control the pressure regulating device to work according to the adjustment parameter, so that the end effector operates according to the target force.

[0042] The present application also provides a storage medium, on which a computer program is stored, and when the computer program is executed, the steps executed by the above control method of the end effector are realized.

[0043] The present application also provides an electronic device, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor calls the computer program in the memory, the steps executed by the above control method of the end effector are realized.

[0044] The present application provides a control method for an end effector. The actual output force of the end effector on the load is obtained through a force sensor, and the pressure inside the pipeline is also obtained through a pressure sensor, and the indirect force that can reflect the acting situation of the fluid on the end effector is calculated. The present application also calculates the output error between the actual output force and the target force, and sets the weight information of the force sensor and the pressure sensor according to the output error. The present application determines the adjustment parameter based on the weight information, the actual output force, the indirect force, and the target force, and performs pressure adjustment, so that the end effector outputs a stable target force to the load. In the above process, the force sensor and the pressure sensor jointly participate in the control process of the end effector, which can reduce the interference of the external environment on the control accuracy. The present application sets the weight information according to the output error, and can dynamically adjust the weights of the force sensor and the pressure sensor based on the actual working conditions, reducing the influence of pressure transmission delay and load mutation on the control effect of the end effector. Therefore, the present application can accurately control the end effector to output a stable force. The present application also provides a mechanical device, a storage medium, and an electronic device at the same time, which have the above beneficial effects and will not be elaborated here. Description of the Drawings

[0045] To more clearly illustrate the embodiments of the present application, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0046] Figure 1 Flow chart of a control method for an end effector provided by an embodiment of the present application;

[0047] Figure 2 Schematic diagram showing the relationship between the first output error and the first weight provided by an embodiment of the present application;

[0048] Figure 3 Schematic diagram showing the relationship between the second output error and the first weight provided by an embodiment of the present application;

[0049] Figure 4 Schematic diagram showing the relationship between the third output error and the first weight provided by an embodiment of the present application;

[0050] Figure 5 Schematic diagram showing the relationship between the fourth output error and the first weight provided by an embodiment of the present application;

[0051] Figure 6 Schematic diagram of a hydraulic system provided by an embodiment of the present application;

[0052] Figure 7 Logic block diagram of a force stability control system for a dynamic fusion hydraulic end effector provided by an embodiment of the present application;

[0053] Figure 8 Logic flow chart of a dynamic weight adjustment provided by an embodiment of the present application;

[0054] Figure 9 Fault detection logic diagram provided by an embodiment of the present application;

[0055] Figure 10 Another schematic diagram of a hydraulic system provided by an embodiment of the present application. Detailed implementation manners

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

[0057] At present, the force stability control of hydraulic or pneumatic control systems mainly relies on the traditional PID (Proportion Integral Differential) algorithm combined with single-sensor feedback; some improved solutions attempt multi-sensor data fusion, but their solutions only mix the signals of force sensors and pressure sensors according to fixed weights. In addition, passive compliance control and electric-driven end effectors can only be applied in specific scenarios, with fewer applicable scenarios. Although the above can meet some requirements in basic control scenarios, limited by the strong non-linear characteristics of the hydraulic system and complex working conditions, there are still significant technical bottlenecks. In view of the technical problems existing in the above related technologies, this embodiment provides a new control scheme for the end effector through the following embodiments, which can accurately control the end effector to output a stable force.

[0058] Please refer to the following Figure 1 , Figure 1 which is a flowchart of a control method for an end effector provided by an embodiment of the present application.

[0059] The specific steps may include:

[0060] S101: Obtain the actual output force collected by the force sensor;

[0061] Among them, this embodiment can be applied to the controller of mechanical equipment, and the mechanical equipment can be any automated equipment with a pressure regulating device and an end effector, such as a hydraulic press, an injection molding machine, a robot end tool, a numerical control machine tool, a construction machinery, etc. The above end effector is an actuator driven by a fluid, and the pressure regulating device is connected to the end effector through a preset pipeline, and the pressure regulating device is used to adjust the pressure of the fluid in the preset pipeline.

[0062] The above mechanical equipment also includes a pressure sensor and a force sensor. The pressure sensor is arranged in the preset pipeline, and the force sensor is arranged at the contact surface between the end effector and the load. The pressure sensor is used to detect the pressure magnitude in the preset pipeline, and the force sensor is used to detect the acting force magnitude of the end effector on the load. The actual output force, indirect force, and target force mentioned in this embodiment are all values used to describe the acting force magnitude.

[0063] In this embodiment, the end effector is a device installed at the end of a robotic arm or a driving device in mechanical equipment, and is used to perform surface treatment on the surface of a load according to a set force value. The load is the operating object of the end effector, such as workpieces such as metal parts, electronic components, and medical devices.

[0064] In this embodiment, the controller can be electrically connected to the force sensor, and the controller can obtain the actual output force collected by the force sensor. The above actual output force is the actual force exerted by the end effector on the load. As a feasible implementation manner, a plurality of force sensors can be arranged on the surface of the end effector, and the controller can calculate the above actual output force based on the signals collected by all the force sensors.

[0065] S102: Obtain the pressure inside the pipeline collected by the pressure sensor, and calculate the indirect force according to the pressure inside the pipeline;

[0066] Among them, in this embodiment, the controller can be electrically connected to the pressure sensor, and the controller can obtain the pressure inside the pipeline collected by the pressure sensor. The pressure inside the pipeline is the pressure of the fluid in the preset pipeline, and the above fluid can be a liquid or a gas. As a feasible implementation manner, a plurality of pressure sensors can be arranged in the above preset pipeline, and the controller can calculate the above pressure inside the pipeline based on the signals collected by all the pressure sensors.

[0067] On the basis of obtaining the pressure inside the pipeline, this step can calculate the force exerted by the fluid on the end effector according to the pressure inside the pipeline, that is, the indirect force.

[0068] In this embodiment, the operations of S101 and S102 can be respectively executed cyclically according to a certain period to determine the latest actual output force and indirect force. After obtaining the latest actual output force and indirect force, the related operations of S103 to S105 can be executed to realize the continuous control of the end effector.

[0069] As a feasible implementation manner, the above end effector can be an actuator with a built-in hydraulic cylinder; correspondingly, this embodiment can calculate the indirect force in the following manner: calculate the indirect force according to the effective area of the hydraulic cylinder and the pressure inside the pipeline. The effective area of the hydraulic cylinder refers to the actual area where the hydraulic oil acts on the piston. In this embodiment, the effective area can be calculated according to the diameter of the hydraulic cylinder, and the product of the effective area and the pressure inside the pipeline is used as the indirect force.

[0070] S103: Determine the output error according to the difference between the actual output force and the target force, and set the weight information according to the output error;

[0071] Before this step, the target force of the end effector can also be determined, that is, the magnitude of the force that the end effector needs to exert on the load. The target force can be a parameter input by the user on the operation interface, or a parameter transmitted by other terminals, or a parameter calculated during the working process of the mechanical equipment.

[0072] Among them, based on the obtained actual output force and target force, this step can determine the difference between the actual output force and the target force, that is, the output error. The above output error is used to describe the degree of difference between the force actually output by the end effector and the control target.

[0073] As a supplementary implementation manner, a plurality of force sensors are arranged on the surface of the end effector for measuring the forces at different positions. The force corresponding to each force sensor measurement value is set as the local output force. All local output forces are evaluated, and the local output forces with obvious deviations from the target force are excluded to eliminate the influence of outliers on the measurement results. Then, based on the positions of the force sensors, weighted calculation is performed on the remaining local output forces, and the weighted calculation result is used as the actual output force. Furthermore, the output error is determined based on the difference between the actual output force and the target force. The above local output forces with obvious deviations from the target force refer to: the local output forces whose absolute value of the difference from the target force is greater than the critical value.

[0074] This step can set weight information according to the above output error; the above weight information includes the first weight corresponding to the force sensor and the second weight corresponding to the pressure sensor. That is, this step can set the first weight corresponding to the force sensor and the second weight corresponding to the pressure sensor according to the output error.

[0075] The above first weight and second weight are used to determine whether to rely more on the actual output force or the indirect force during the control process, so as to flexibly adjust the control strategy according to the actual working conditions, reduce the influence of external interference and internal changes on the control effect of the end effector, and thus achieve more accurate and stable force control.

[0076] S104: Determine the adjustment parameter based on the weight information, the actual output force, the indirect force and the target force;

[0077] Among them, this step can perform weighted calculation on the actual output force, the indirect force and the target force based on the weight information, and then determine the adjustment parameter of the pressure regulating device according to the weighted calculation result, so as to change the pressure in the preset pipeline.

[0078] In the traditional scheme, a fixed weight fusion strategy is usually used to determine the adjustment parameter. However, this strategy cannot adapt to dynamic working conditions, has a response lag in large error scenarios, and has difficulties in multi-sensor data synchronization and lacks a fault tolerance mechanism. The dynamic weight fusion algorithm provided in this embodiment combines a force sensor and a pressure sensor to dynamically adjust the weight information for controlling the pressure regulating device, replacing the traditional fixed weight fusion method, and can overcome the problem of insufficient sensor fusion ability in the traditional scheme.

[0079] The above pressure regulating device can be selected from a servo directional valve, a proportional pressure reducing valve or a gas-liquid booster pump, or they can be used in combination. Correspondingly, the above adjustment parameters are the control quantities corresponding to the pressure regulating device, which are used to adjust the pressure in the preset pipeline to meet the requirement of the end effector for outputting a stable acting force on the load.

[0080] S105: Control the pressure regulating device to work according to the adjustment parameters, so that the end effector operates according to the target force.

[0081] Among them, the pressure regulating device can adjust the valve opening and the boosting ratio according to the above adjustment parameters, and then change the fluid pressure input to the end effector, so as to compensate for the influence of pressure transmission delay and load mutation, so that the end effector outputs a stable acting force on the load, and the actual output force is equal to the target force.

[0082] In this embodiment, the actual output force of the end effector on the load is obtained through a force sensor, and the pressure in the pipeline is also obtained through a pressure sensor and the indirect force reflecting the action of the fluid on the end effector is calculated. This embodiment also calculates the output error between the actual output force and the target force, and sets the weight information of the force sensor and the pressure sensor according to the output error. Based on the weight information, the actual output force, the indirect force and the target force, this embodiment determines the adjustment parameters and performs pressure adjustment, so that the end effector outputs a stable target force on the load. In the above process, the force sensor and the pressure sensor jointly participate in the control process of the end effector, which can reduce the interference of the external environment on the control accuracy. By setting the weight information according to the output error, this embodiment can dynamically adjust the weights of the force sensor and the pressure sensor based on the actual working conditions, and reduce the influence of pressure transmission delay and load mutation on the control effect of the end effector. Therefore, this embodiment can accurately control the end effector to output a stable force.

[0083] As a further introduction to Figure 1 the corresponding embodiment, the above embodiment can directly use the difference between the actual output force and the target force as the output error, or set the absolute value of the difference between the actual output force and the target force as the output error.

[0084] In this embodiment, the corresponding relationship between the output error and the weight information can be preset. After determining the output error, the first weight corresponding to the force sensor and the second weight corresponding to the pressure sensor can be determined based on the above corresponding relationship. In this embodiment, the corresponding relationship between the output error and the weight information can be determined according to the test data through actual tests or simulation tests on mechanical equipment. This embodiment adopts a dynamic weight fusion architecture that combines a force sensor and a pressure sensor, and proposes an adjustment mechanism for the first weight (i.e., the force sensor influence factor) and the second weight (i.e., the pressure sensor influence factor) that is adaptive based on the output error (i.e., the error range), which can avoid overshoot caused by the superposition of hydraulic pipeline pressure transmission delay and load mutation, and solve the problems of rigid fusion strategy and lag in dynamic response in traditional solutions.

[0085] This embodiment can stipulate that both the first weight and the second weight are greater than 0, and the sum of the first weight and the second weight is a fixed value, such as 1. Therefore, the corresponding relationship between the output error and the weight information can be the corresponding relationship between the output error and the first weight. After determining the first weight, the second weight can be obtained by subtracting the first weight from the fixed value. Similarly, the corresponding relationship between the output error and the weight information can also be the corresponding relationship between the output error and the second weight.

[0086] As a feasible implementation manner, this embodiment can use a decreasing function to describe the corresponding relationship between the output error and the first weight; please refer to Figure 2 and Figure 3 , Figure 2 which is the first schematic diagram of the relationship between the output error and the first weight provided by the embodiment of the present application, Figure 3 and is the second schematic diagram of the relationship between the output error and the first weight provided by the embodiment of the present application. The abscissa in the figure is the output error, and the ordinate is the first weight.

[0087] As a feasible implementation manner, this embodiment can use a piecewise function to describe the corresponding relationship between the output error and the first weight; please refer to Figure 4 , Figure 4 which is the third schematic diagram of the relationship between the output error and the first weight provided by the embodiment of the present application. The abscissa in the figure is the output error, and the ordinate is the first weight. .

[0088] Specifically, this embodiment can set the weight information in the following manner:

[0089] If the output error is less than or equal to the first threshold, the first weight is set to the first fixed value, and the second weight is set to the second fixed value;

[0090] If the output error is greater than the first threshold and less than the second threshold, set the first weight and the second weight according to the output error; wherein, the first weight is negatively correlated with the output error, and the second weight is positively correlated with the output error;

[0091] If the output error is greater than the second threshold, set the first weight to a third fixed value and the second weight to a fourth fixed value; wherein, the first fixed value is greater than the third fixed value, and the second fixed value is less than the fourth fixed value.

[0092] Before this step, the target force of the end effector can also be determined , that is, the force that the end effector needs to exert on the load. The above first threshold and second threshold can be set according to the target force . If the above first threshold is 2 , the second threshold is 5 , the first fixed value is 0.8, the second fixed value is 0.2, the third fixed value is 0.2, and the fourth fixed value is 0.8, then the relationship between the output error and the first weight is as Figure 5 shown Figure 5 , which is the fourth schematic diagram of the relationship between the output error and the first weight provided by the embodiments of the present application.

[0093] Due to the different installation positions, there is a contradiction between the accuracy and response speed of the force sensor and the pressure sensor, that is: the force sensor has high accuracy but has a delay, and the pressure sensor has a fast response but is vulnerable to pipeline noise interference. Through the above setting method of the first weight and the second weight, the advantages of the force sensor and the pressure sensor can be integrated to achieve high-precision, low-delay, and strong anti-interference ability of the end effector control. In addition, in the hydraulic control scenario, there is a situation where the valve flow gain drifts due to the change of the oil temperature, and the high-frequency noise of the pressure sensor reduces the signal-to-noise ratio. However, this embodiment can dynamically set the weights of the force sensor and the pressure sensor according to the actual working conditions, and can effectively cope with multi-source noise interference.

[0094] As for Figure 1For a further introduction of the corresponding embodiment, in the related art, the PID algorithm is usually used to control the pressure regulating device, but the above method is easily affected by non-linear interference. For example, the dead zone of the hydraulic valve and the compressibility of the oil will cause the force-displacement relationship to exhibit non-linear characteristics, which makes it difficult for the traditional PID algorithm to achieve accurate modeling. In addition, the integral term of the PID algorithm is prone to saturation when facing the dead zone of the hydraulic valve and friction non-linearity, thus causing overshoot and continuous oscillation problems. At the same time, although the model predictive control (MPC, Model Predictive Control) has high control accuracy, it depends on an accurate system model and has a high computational complexity, making it difficult to meet the requirements of real-time operation.

[0095] In view of the problems of rigid control algorithm and easy risk of integral saturation existing in the above PID algorithm, the present application provides a solution for determining the adjustment parameters of the pressure regulating device based on the PD (Proportional-Differential) algorithm. The specific process is as follows:

[0096] Step A1: Determine the target force of the end effector.

[0097] Step A2: Take the difference between the target force and the actual output force as the first error.

[0098] Step A3: Take the difference between the target force and the indirect force as the second error.

[0099] Step A4: Perform weighted calculation on the first error and the second error based on the weight information to obtain the proportional term.

[0100] Specifically, the calculation formula for the proportional term P is: , represents the proportional gain, represents the first weight, represents the target force, represents the actual output force, represents the second weight, represents the indirect force. As a feasible implementation, + = 1, is dynamically adjusted according to the magnitude of the output error.

[0101] Step A5: Perform differential calculation on the first error to obtain the differential term.

[0102] Specifically, the calculation formula for the differential term D is: , represents the differential gain, represents the differential of the first error, and dt represents the differential with respect to time.

[0103] Step A6: Determine the adjustment parameter according to the proportional term and the differential term.

[0104] Specifically, the adjustment parameter is calculated as follows:

[0105] .

[0106] This solution realizes a de-integrated PD control design, cancels the integral term of the traditional PID algorithm, solves the integral saturation problem caused by the non-linear characteristics of the hydraulic system (such as valve dead zone, friction), and is superior to the effect of the traditional PID algorithm with an integral term.

[0107] As a further introduction to the Figure 1 corresponding embodiment, before setting the weight information according to the output error, fault detection can also be performed in the following manner: set the absolute value of the difference between the actual output force and the indirect force as the system residual; determine whether the duration for which the system residual continuously exceeds the third threshold is greater than the first target duration; if so, determine that a fault exists and start the control process of the end effector in the fault mode; if not, enter the step of setting the weight information according to the output error.

[0108] Specifically, in this embodiment, a first timer can be started when the system residual exceeds the third threshold, and the first timer can be stopped and reset when the system residual is less than or equal to the third threshold; the time recorded by the first timer is the duration for which the system residual continuously exceeds the third threshold. If this duration is greater than the first target duration, it is determined that a fault exists, so as to start the control process of the end effector in the fault mode.

[0109] In the related art, the single-sensor solution has no redundant design. When the sensor fails, the system cannot degrade and operate, resulting in the interruption of processing. To address the above problems, this embodiment provides a control process for the end effector in the fault mode, which specifically includes: determining a temporary adjustment parameter according to the actual output force or the indirect force, and controlling the pressure adjustment device to operate according to the temporary adjustment parameter; if the duration for which the system residual continuously is less than or equal to the fourth threshold is greater than the second target duration, enter the step of setting the weight information according to the output error. Among them, the third threshold is greater than or equal to the fourth threshold.

[0110] In this embodiment, a second timer can be started when the system residual is less than or equal to the fourth threshold, and the second timer can be stopped and reset when the system residual exceeds the fourth threshold; the time recorded by the second timer is the duration for which the system residual continuously is less than or equal to the fourth threshold. If this duration is greater than the second target duration, it indicates that the fault has been recovered, and the step of setting the weight information according to the output error can be entered.

[0111] Specifically, during a fault, in this embodiment, the temporary adjustment parameters can be determined only using the actual output force, and the pressure adjustment device can be controlled to operate according to the temporary adjustment parameters. Or the temporary adjustment parameters can be determined only using the indirect force, and the pressure adjustment device can be controlled to operate according to the temporary adjustment parameters. If the temporary adjustment parameters are determined according to the actual output force, it is equivalent to setting the first weight to 1 and the second weight to 0. If the temporary adjustment parameters are determined according to the indirect force, it is equivalent to setting the first weight to 0 and the second weight to 1. Through the above solution, the defects of insufficient reliability and adaptability in the related art can be overcome.

[0112] The above embodiment of the present application provides a control logic integrating residual detection and mode switching. That is, when the duration for which the system residual continuously exceeds the third threshold is greater than the first target duration, it is determined that a fault exists. The first weight is set to 0, and the second weight is set to 1. At this time, only the pressure sensor works to maintain the fast response of the control. When the duration for which the system residual continuously is less than or equal to the fourth threshold is greater than the second target duration, the fault is recovered, and then the normal mode is switched back. The above dual-sensor fusion fault handling method integrates residual detection and degradation control logic, switches to the pure pressure sensor feedback mode when the force sensor fails, maintains the basic functions of the system, and improves the reliability of the end effector control.

[0113] The following uses an embodiment in actual application to illustrate the process described in the above embodiment.

[0114] This embodiment provides a hydraulic end effector force stability control system and method based on dual-sensor dynamic fusion, which is applicable to the force stability control processing method for workpiece surface strengthening and can perform surface treatment on the workpiece surface according to the set force value. This embodiment can be widely applied to intelligent manufacturing fields such as numerically controlled machine tools and stamping equipment that require precise force control.

[0115] Please refer to Figure 6 , Figure 6 which is a schematic diagram of a hydraulic system provided by an embodiment of the present application. Figure 1The mechanical equipment mentioned in the corresponding embodiment may also have the above hydraulic system. The hydraulic system includes a hydraulic box 1, a pump 2, a relief valve 3, a gas-liquid booster pump 4, a three-position four-way directional control valve 5, a pressure sensor 6, a flow regulating valve 7, an end effector 8, a force sensor 9, an air storage tank 10, a pneumatic proportional valve 11, and a proportional pressure reducing valve 12. The hydraulic oil is output by the pump 2, and the initial system pressure regulation is carried out through the relief valve 3. The relief valve 3 is equipped with a pressure sensor M, which can display the currently adjusted pressure value. Then, the system pressure increase is achieved through the gas-liquid booster pump 4, and the increased pressure value can be read through the pressure sensor after the gas-liquid booster pump 4. Then, the reversing function of the end effector 8 is achieved through the three-position four-way directional control valve 5, that is, the action of the end effector 8 is controlled. After reversing through the three-position four-way directional control valve 5, it enters the proportional pressure reducing valve 12 for pressure regulation. The pressure regulation of the proportional pressure reducing valve 12 adjusts the control amount of the proportional valve opening in a way of dual-sensor dynamic fusion. Finally, the flow rate is regulated through the flow regulating valve 7, and finally the output of the stable pressure of the end effector force is achieved. In this embodiment, the force sensor and the pressure sensor collect signals and transmit them to the controller, and the control unit transmits corresponding control instructions to the proportional pressure reducing valve.

[0116] The above force-stable control system for a hydraulic end effector based on dual-sensor dynamic fusion includes a data acquisition device, a controller (also known as a control unit), and an execution unit. Please refer to Figure 7 , Figure 7 which is a logic block diagram of a force-stable control system for a dynamic fusion hydraulic end effector provided by an embodiment of the present application. The data acquisition device includes a sensing unit and a target force setting unit. The sensing unit includes a force sensor and a pressure sensor. The force sensor collects the force value of the end effector (i.e., the actual output force), and the pressure sensor collects the pressure value of the system (i.e., the pressure in the pipeline). The target force setting unit is used to input the target force that the end effector needs to output to the controller. The above force sensor can be a high-precision force sensor installed on the contact surface between the hydraulic end effector and the load, with a range of 0 - 5000 N and an accuracy of 0.5 . N represents Newton. In this embodiment, the accuracy described in percentage and the accuracy presented in percentage are both defined based on the full scale (FS, Full Scale). The above pressure sensor can be a high-frequency pressure sensor integrated in the oil inlet cavity of the hydraulic cylinder, with a range of 0 - 10 MPa and an accuracy of 0.2 . MPa represents megapascal.

[0117] The carrier of the controller is a PLC (Programmable Logic Controller) programmable logic controller, which calculates the first weight corresponding to the force sensor using a dynamic fusion algorithm , and the second weight corresponding to the pressure sensor ; The controller can calculate the opening control amount of the proportional relief valve (i.e., the adjustment parameter of the proportional relief valve) through a control algorithm, and precisely control the end force value by using the proportional relief valve. The controller can also implement fault detection and switching logic. The above controller implants the control algorithm using a PLC, supports the access of force sensors and pressure sensors, and controls the opening of the proportional valve through the output module; the controller has a microsecond-level instruction cycle, which can meet the real-time requirements of dynamic weight adjustment; the controller can apply complex control strategies such as de-integrated PD algorithm, fault detection logic, and feedforward compensation.

[0118] The execution unit includes a proportional relief valve, a hydraulic cylinder, and an end effector. The proportional relief valve is mainly the execution carrier of the control algorithm, used to precisely control the output force F of the hydraulic cylinder by adjusting the flow rate to achieve stable force control of the end effector. The above hydraulic cylinder is built into the end effector. The parameters of the above proportional relief valve are as follows: flow rate 0 - 15 L / min, pressure rating 3 - 10 MPa, response sensitivity 0.5 , hysteresis 5 , repeatability accuracy 1 . The above hydraulic cylinder can be a double-acting hydraulic cylinder, and its parameters are as follows: cylinder diameter 63 mm, rod diameter 30 mm, stroke 30 mm, and a displacement sensor with an internal accuracy of 0.01 mm is installed.

[0119] This embodiment is implemented by a hydraulic pressure control method. The output force of the end effector is stably controlled by combining the measured value of the force sensor carried by the end effector and the measured value of the pressure sensor output by the proportional relief valve according to weight optimization. By obtaining the measured value of the force sensor of the end effector (i.e., the actual output force) and the measured value of the pressure sensor (i.e., the pressure in the pipeline), it is converted into an indirect force ( is the effective acting area of the hydraulic cylinder of the end effector), and then the target force (i.e., the stable force value to be achieved) is set. According to and error, the weight of the force sensor and the weight of the pressure sensor are dynamically adjusted to generate the proportional valve opening control amount u(t). When a force sensor failure is detected, it switches to the pure pressure feedback control mode. 、 and u(t) represent the first weight, the second weight, and the proportional valve opening control amount corresponding to the t-th moment.

[0120] Please refer to Figure 8 , Figure 8 which is a dynamic weight adjustment logic flowchart provided by an embodiment of the present application. The controller can perform the following operations:

[0121] Step B1: Obtain real-time data;

[0122] The above real-time data includes the target force , the measured value of the force sensor , and the measured value of the pressure sensor .

[0123] Step B2: Calculate the indirect force;

[0124] Among them, the target force can be sent by the host computer (such as a numerical control system), and the controller reads the measured value of the force sensor in real time and the measured value of the pressure sensor ;

[0125] The calculation formula for the indirect force is: , the effective area of the hydraulic cylinder , R is the diameter of the hydraulic cylinder, such as 63 mm.

[0126] Step B3: Calculate the output error;

[0127] Among them, the calculation formula for the output error ec is: .

[0128] Step B4: Determine the interval where the output error is located; if the output error is less than or equal to 2 , it means that it is in the steady state mode at this time, = 0.8, = 0.2, and the high-precision characteristics of the force sensor are preferentially used for control; if the output error is greater than 2 and less than 5 , it means that it is in the transition mode at this time, and it can be determined according to the following formula and : , = 1 - ; if the output error is greater than or equal to 5 , it means that it is in the dynamic mode at this time, = 0.2, = 0.8, and the fast response characteristics of the pressure sensor are preferentially used for control.

[0129] Step B5: Calculate the residual r; if r > 10 for 5 seconds continuously, then force = 0, = 1; otherwise, obtain the real-time data again;

[0130] Among them, the calculation formula of the residual (i.e., the system residual) r is .

[0131] Step B6: Output the weight;

[0132] The method of calculating the weight in the above step B4 reflects the dynamic fusion weight algorithm of the controller. The fusion error production algorithm of the controller is as follows: ; represents the calculation result of the fusion error production algorithm.

[0133] The de-integral PD control algorithm of the controller is as follows: ;

[0134] The above is the adjustment parameter at time t; represents the proportional gain tuned by the step response method; represents the differential gain calculated according to the critical oscillation period.

[0135] The healing logic of the controller includes a residual detection algorithm and a degradation control strategy. Please refer to Figure 9 , Figure 9 which is a fault detection logic diagram provided by an embodiment of the present application. After starting the normal control mode, after fusing the sensor data, the residual r is calculated. If r > 10 , and it lasts for more than 1 second, then enter the degradation control mode (at this time = 0, = 1); if r ≤ 10 , then continue to enter the normal control mode. In the degradation control mode, only the pressure sensor is used to calculate the control parameters until r ≤ 5 and it lasts for 2 seconds.

[0136] The residual detection algorithm is: by calculating the force value deviation between the force sensor and the pressure sensor in real time ; The fault determination condition is: r > 10 , and it lasts for more than 1 second, and it is determined as a fault accordingly.

[0137] The degradation control strategy is as follows: when a fault is triggered, forcibly set = 0, = 1, and only rely on the feedback of the pressure sensor. At this time, the adjustment parameter .

[0138] The fault recovery condition is r ≤ 5 Last for 2 seconds, and then it can automatically switch back to the normal mode.

[0139] In the scene of constant-force machining of a CNC machine tool cutter, the above-mentioned force stability control scheme for the hydraulic end effector based on dual-sensor dynamic fusion can be used. In the scene of constant-force machining of a CNC machine tool cutter, the end effector is the cutter, and the specific configuration parameters are as follows:

[0140] Hydraulic cylinder: cylinder diameter 63mm, stroke 50mm.

[0141] Proportional valve: flow rate 0 - 10L / min.

[0142] Force sensor: measuring range 0 - 5000N, accuracy 0.5 , installed at the tool clamping end.

[0143] The controller is configured with an analog input module and a PWM (Pulse Width Modulation) output module.

[0144] The pressure regulating device can be a proportional pressure reducing valve.

[0145] If the target force is 3000N, the dynamic weight adjustment process is as follows:

[0146] Steady state mode: If ≤60N, set =0.8, =0.2, the force sensor dominates the control, and the measured steady state error ≤ 30N.

[0147] Dynamic mode: When the tool pressure suddenly changes and the error ≥150N, set =0.2, =0.8, the pressure sensor responds quickly, and the adjustment time is 0.1 second.

[0148] This embodiment can simulate the failure of the force sensor (signal set to zero), and the residual =3000N. After 0.5 seconds, the degradation mode is triggered and switched to pure pressure feedback, and the measured error ≤ 90N.

[0149] The above-mentioned pressure regulating device can also be a servo direction valve. Please refer to Figure 10 , Figure 10 which is another schematic diagram of the hydraulic system provided by the embodiment of the present application. This hydraulic system includes a hydraulic box 1, a pump 2, a relief valve 3, a gas-liquid booster pump 4, a three-position four-way directional control valve 5, a pressure sensor 6, a flow regulating valve 7, an end effector 8, a force sensor 9, an air storage tank 10, a pneumatic proportional valve 11, and a servo direction valve 13.

[0150] An embodiment of the present application further provides a mechanical device, including a controller, a pressure regulating device, a pressure sensor, an end effector, and a force sensor. The end effector is an actuator driven by a fluid. The pressure regulating device is connected to the end effector through a preset pipeline. The pressure regulating device is used to adjust the pressure of the fluid in the preset pipeline. The pressure sensor is arranged in the preset pipeline, and the force sensor is arranged at the contact surface between the end effector and the load;

[0151] When the controller works, the operations performed include:

[0152] Obtain the actual output force collected by the force sensor;

[0153] Obtain the pressure in the pipeline collected by the pressure sensor, and calculate the indirect force according to the pressure in the pipeline; wherein, the indirect force is the acting force of the fluid on the end effector;

[0154] Determine the output error according to the difference between the actual output force and the target force, and set the weight information according to the output error; wherein, the weight information includes a first weight corresponding to the force sensor and a second weight corresponding to the pressure sensor;

[0155] Determine the adjustment parameter based on the weight information, the actual output force, the indirect force, and the target force;

[0156] Control the pressure regulating device to work according to the adjustment parameter, so that the end effector operates according to the target force.

[0157] The above-mentioned pressure regulating device includes any one or a combination of a servo direction valve, a proportional pressure reducing valve, and a gas-liquid booster pump.

[0158] Since the embodiments of the device part correspond to the embodiments of the method part, please refer to the description of the embodiments of the method part for the embodiments of the device part, and will not be elaborated here.

[0159] The present application also provides a storage medium, on which a computer program is stored. When the computer program is executed, the steps provided by the above embodiments can be implemented. The storage medium may include: various media that can store program codes such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disc.

[0160] The present application also provides an electronic device, which may include a memory and a processor. A computer program is stored in the memory. When the processor calls the computer program in the memory, the steps provided in the above embodiments can be implemented. Of course, the electronic device may also include various network interfaces, power supplies and other components.

[0161] The various embodiments in the specification are described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the similarities and common parts among the various embodiments, reference can be made to each other. For the device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description in the method section. It should be noted that for those of ordinary skill in the art in the technical field of the present application, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the present application.

[0162] It should also be noted that in this specification, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or device including the said element.

Claims

1. A control method for an end effector, characterized in that, A controller applied to a mechanical device, and the control method of the end effector includes: Step 1: Obtain the actual output force collected by the force sensor; obtain the pressure inside the pipeline collected by the pressure sensor, and calculate the indirect force according to the pressure inside the pipeline; wherein, the indirect force is the acting force of the fluid on the end effector; Step 2: Determine the output error according to the difference between the actual output force and the target force, and set the weight information according to the output error; wherein, the weight information includes a first weight corresponding to the force sensor and a second weight corresponding to the pressure sensor; Step 3: Determine the adjustment parameter based on the weight information, the actual output force, the indirect force, and the target force; Step 4: Control the pressure regulating device to work according to the adjustment parameter, so that the end effector operates according to the target force.

2. The control method of the end effector according to claim 1, characterized in that Determine the output error according to the difference between the actual output force and the target force, and set the weight information according to the output error, including: Set the absolute value of the difference between the actual output force and the target force as the output error; If the output error is less than or equal to the first threshold, set the first weight as a first fixed value and the second weight as a second fixed value; If the output error is greater than the first threshold and less than the second threshold, set the first weight and the second weight according to the output error; wherein, the first weight is negatively correlated with the output error, and the second weight is positively correlated with the output error; If the output error is greater than the second threshold, set the first weight as a third fixed value and the second weight as a fourth fixed value; wherein, the first fixed value is greater than the third fixed value, and the second fixed value is less than the fourth fixed value.

3. The control method of the end effector according to claim 1, characterized in that, Determine the adjustment parameter based on the weight information, the actual output force, the indirect force, and the target force, including: Take the difference between the target force and the actual output force as the first error; Take the difference between the target force and the indirect force as the second error; Perform weighted calculation on the first error and the second error based on the weight information to obtain a proportional term; Perform differential calculation on the first error to obtain a differential term; Determine the adjustment parameter according to the proportional term and the differential term.

4. The control method of the end effector according to claim 3, characterized in that, The calculation formula for the proportional term P is as follows: , represents the proportional gain, represents the first weight, represents the target force, represents the actual output force, represents the second weight, represents the indirect force; The calculation formula of the differential term D is as follows: , represents the differential gain, represents the differentiation of the first error, and dt represents the differentiation with respect to time; The adjustment parameter .

5. The control method of the end effector according to claim 1, characterized in that Before setting the weight information according to the output error, it further includes: Set the absolute value of the difference between the actual output force and the indirect force as the system residual; Judge whether the duration for which the system residual continuously exceeds the third threshold is greater than the first target duration; If so, determine that a fault exists and start the control process of the end effector in the fault mode; If not, enter the step of setting the weight information according to the output error.

6. The control method of the end effector according to claim 5, characterized in that, The control process of the end effector in the fault mode includes: Determine a temporary adjustment parameter according to the actual output force or the indirect force, and control the pressure regulating device to work according to the temporary adjustment parameter; If the duration for which the system residual continuously is less than or equal to the fourth threshold is greater than the second target duration, enter the step of setting the weight information according to the output error; wherein, the third threshold is greater than or equal to the fourth threshold.

7. The control method of the end effector according to claim 1, wherein The end effector is an actuator with a built-in hydraulic cylinder; Correspondingly, calculating the indirect force according to the pressure in the pipeline includes: Calculating the indirect force according to the effective area of the hydraulic cylinder and the pressure in the pipeline.

8. A mechanical device, characterized in that, The mechanical device includes a controller, a pressure regulating device, a pressure sensor, an end effector, and a force sensor. The end effector is an actuator driven by a fluid. The pressure regulating device is connected to the end effector through a preset pipeline. The pressure regulating device is used to adjust the pressure of the fluid in the preset pipeline. The pressure sensor is arranged in the preset pipeline. The force sensor is arranged at the contact surface between the end effector and the load; When the controller works, the operations performed include: Step 1: Obtain the actual output force collected by the force sensor; obtain the pressure in the pipeline collected by the pressure sensor, and calculate the indirect force according to the pressure in the pipeline; wherein, the indirect force is the acting force of the fluid on the end effector; Step 2: Determine the output error according to the difference between the actual output force and the target force, and set the weight information according to the output error; wherein, the weight information includes a first weight corresponding to the force sensor and a second weight corresponding to the pressure sensor; Step 3: Determine the adjustment parameter based on the weight information, the actual output force, the indirect force, and the target force; Step 4: Control the pressure regulating device to work according to the adjustment parameter, so that the end effector operates according to the target force.

9. An electronic device, characterized in that, It includes a memory and a processor. When the processor calls the computer program stored in the memory, the steps of the control method of the end effector according to any one of claims 1 to 7 are implemented.

10. A storage medium, characterized in that, The computer-executable instructions are stored in the storage medium. When the computer-executable instructions are loaded and executed by the processor, the steps of the control method of the end effector according to any one of claims 1 to 7 are implemented.

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