Electric-powered loader boom cooperative control method

Abstract

The application discloses an electric loader arm cooperative control method in the field of electric control technology of engineering machinery, and steps are as follows: collecting real-time position of an arm electric cylinder, output torque size, bucket displacement and turning angle size, force size at a connecting hinge point between the arm and the bucket, walking gear position signal and its torque size, obtaining an electric loader working condition type through a working condition identification model from the collected data, simultaneously selecting an arm cooperative mode according to the working condition type and rules provided by a self-defined rule library by a cooperative mode judging device, and outputting an arm cooperative mode signal, a double-cylinder cooperative control signal output by an arm synchronous controller and an output rotating speed of a servo motor of the two-side arm electric cylinder of the motor driver according to the received arm cooperative control signal, so that the electric cylinder outputs ideal displacement or torque size, efficient cooperative control of the two-side arm electric cylinder of the electric loader is realized, and operation safety and operation efficiency of a working device of the electric loader are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric control of engineering machinery, in particular to a method for cooperative control of an electric loader boom. BACKGROUND

[0002] As an important model in the existing engineering field, loaders are widely used in key tasks such as mine transportation and urban construction, but traditional fuel loaders have serious carbon emission problems. With the increasing consumption of traditional energy and the increasing environmental problems, the electrification of loaders has become an important measure for China to achieve "green" and "sustainable" development. In the early stage of loader electrification, high-power motors are mainly used to replace internal combustion engines as the power source of the whole machine. In order to further improve the electrification level of the loader, independent motor drive systems are configured for each wheel, so as to realize the electrification of the loader chassis system. However, due to the complex multi-structure coupling of the loader working device and the continuous external load changes during operation, the working device has not yet realized pure electrification, and the traditional hydraulic driving mode is still retained. Compared with the pure electric driving mode, the working device of this traditional hydraulic driving adopts a multi-stage transmission mode of "power source-pump oil-valve flow distribution", which causes energy to be gradually lost in the transmission process, resulting in low energy utilization rate. At the same time, the inherent strong nonlinear characteristics of the working device hydraulic system, the dynamic response is complex, and the control accuracy is also difficult to meet the future working device high-efficiency unmanned operation demand. Therefore, it is urgent to upgrade the working device of the loader to realize the full electrification of the loader.

[0003] The working device of the electric loader mainly includes a boom and a bucket, and the boom system is equipped with electric cylinders on both sides. Therefore, the main difficulty of electric control of the working device of the loader is how to synchronously control the electric cylinders on both sides of the boom system. Current research attempts to use position cooperative control strategy to make the output displacement of the boom electric cylinder consistent, so as to realize the cooperation of the two booms under normal working conditions. However, the complex cyclic operation conditions of the loader will lead to frequent unbalanced loading. This single position cooperative mode cannot effectively cope with the unbalanced state caused by serious unbalanced loading, thereby causing the imbalance of the boom structure and seriously affecting the operation safety of the working device of the electric loader. At the same time, this single position cooperative mode lacks attention to the output torque of the boom electric cylinder. Therefore, under the condition of unbalanced loading, the boom electric cylinder on the side with lighter load will produce excess torque output, thereby causing torque loss of the boom electric cylinder and reducing the energy utilization efficiency of the working device of the electric loader. SUMMARY

[0004] This section is intended to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract of the specification and the title of the application in order to avoid obscuring the purpose of this section, the abstract of the specification and the title of the application, and such simplifications or omissions are not to be construed as limiting the scope of the present application.

[0005] Therefore, the purpose of the present application is to provide an electric loader boom cooperative control method, which realizes efficient cooperative control of the electric cylinders of the booms on both sides of the electric loader, and improves the operation safety and efficiency of the working device of the electric loader.

[0006] To solve the above technical problems, according to one aspect of the present application, the present application provides the following technical solutions:

[0007] An electric loader boom cooperative control method comprises:

[0008] S1, sensors are installed on the boom, the bucket and the walking driving part to collect data, including the real-time position of the boom electric cylinder, the output torque size, the displacement and the turning angle size of the bucket, the force size at the hinge point connecting the boom and the bucket, the walking gear signal and the torque size data;

[0009] S2, the collected data is subjected to a working condition identification model to obtain the working condition type of the electric loader, a cooperative mode judging device selects the boom cooperative mode according to the working condition type and relying on the rules provided by a self-defined rule library, and outputs a boom cooperative mode signal;

[0010] S3, a boom synchronous controller calculates the error of the feedback signal according to the received boom cooperative mode signal, and performs calculation and compensation in the cooperative controller, and finally outputs a double-cylinder cooperative control signal;

[0011] S4, a motor driver adjusts the output speed of the servo motors of the booms on both sides according to the received double-cylinder cooperative control signal, so as to drive the electric cylinders to output ideal displacement or torque size, at the same time, the displacement or torque data collected by the sensors installed at the ends of the electric cylinders are fed back to the boom cooperative controller, so as to dynamically adjust the cooperative control mode, thereby realizing efficient cooperative movement between the booms on both sides.

[0012] As a preferred scheme of the electric loader boom cooperative control method, in step S1, a position sensor is used to collect the real-time displacement of the boom and the bucket electric cylinder, an angle sensor is used to collect the lifting angle of the boom and the turning angle of the bucket, a force sensor is used to collect the force size at the hinge point connecting the bucket and the boom, and a digital signal collector and a torque sensor are used to collect the gear signal and the walking torque size of the walking driving.

[0013] As a preferred scheme of the electric loader arm cooperative control method, in step S2, the specific steps of obtaining the electric loader working condition type through the working condition recognition model are as follows: the collected boom electric cylinder displacement, output torque size, bucket displacement and turning angle size, walking gear signal and torque size are taken as feature inputs, then, according to the feature inputs, a plurality of sample data sets are divided by using a random forest algorithm, and independent judgment is performed through a plurality of decision tree classifiers constructed, and finally the working condition type of the current electric loader is accurately recognized through an algorithm voting mechanism.

[0014] As a preferred scheme of the electric loader arm cooperative control method, in step S2, the cooperative mode judge is designed relying on the rule base and the working condition recognition model, wherein the logical judgment rules of the judge are as follows:

[0015]

[0016] Among them, is a cooperative mode signal, is a position cooperative mode signal, is a torque cooperative mode signal; 、 respectively correspond to the torque sizes of the left and right arms, defined as the maximum difference of the load torque sizes of the left and right arms, used to judge whether the arm is in an unbalanced load state; is the output displacement of the left arm electric cylinder, is the output displacement of the right arm electric cylinder, defined as the maximum difference of the output displacements of the left and right arm electric cylinders, used to ensure the structural safety of the arm and the bucket.

[0017] As a preferred scheme of the electric loader arm cooperative control method, in step S3, the synchronization controller is designed by using cross-coupling technology and PID control algorithm according to the received arm cooperative mode signal, and outputs the double-cylinder cooperative control signal in the corresponding arm cooperative mode, wherein the double-cylinder cooperative control signal in the arm cooperative mode includes the position cooperative mode and the torque cooperative mode.

[0018] As a preferred scheme of the electric loader arm cooperative control method, in the position cooperative mode, the output displacements of the two arms are required to be consistent in real time, and the specific implementation steps are as follows:

[0019] Step 1: calculate the synchronization error of the output displacements of the two arms according to the following formula Among them,

[0020]

[0021] wherein: and are the output displacements of the left and right two boom electric cylinders respectively;

[0022] Step2: a synchronous controller is designed by using a PID control algorithm, and the synchronous error is fed back to calculate the output compensation, and finally the double-cylinder position collaborative control signal is output according to the coefficient distribution method, and the formula is as follows:

[0023]

[0024] wherein, , and are three design coefficients of the PID control algorithm in the position collaborative mode, and are the coupling coefficients of the left and right boom electric cylinders in the position collaborative mode, which are calculated by the following formula, and simultaneously satisfy the relationship + =1;

[0025]

[0026] wherein: and are the output displacements of the left and right two boom electric cylinders respectively, is the ideal reference displacement of the left and right two boom electric cylinders.

[0027] As a preferred scheme of the electric loader boom collaborative control method, in the torque collaborative mode, the output torque of the boom electric cylinder and the load torque borne by the boom are required to be consistent, and the specific implementation steps are as follows:

[0028] Step1: the difference between the output torque of the two-side boom electric cylinder and the load torque borne by each side in the torque collaborative mode is calculated according to the following formula ;

[0029]

[0030] wherein: is the output torque of the left and right two boom electric cylinders, is the load torque of the left and right two boom electric cylinders calculated by the following formula, ;

[0031]

[0032] wherein, is the force collected, L is the length of the force arm, i.e., the distance between the connecting hinge point and the electric cylinder of the movable arm;

[0033] Step 2: A synchronous controller is designed using a PID control algorithm, and the feedback synchronization difference is used The output double-cylinder torque coordination control signal is calculated, and the formula is as follows:

[0034]

[0035] wherein, , and are three design coefficients of the PID control algorithm in the torque coordination mode.

[0036] Compared with the prior art, the present application has the beneficial effects that: the present application comprehensively considers the position coordination and torque coordination modes of the electric cylinder of the movable arm of the loader, establishes a dynamic switching mechanism between the position coordination and the torque coordination under different working conditions and different load degrees, overcomes the structural imbalance and energy loss problems of the loader movable arm system under a single position coordination control mode, realizes efficient coordinated control of the electric cylinders on both sides of the movable arm of the electric loader, and improves the operation safety and efficiency of the working device of the electric loader. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the present application will be described in detail below in combination with the drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. Among them:

[0038] Figure 1 is a flowchart of the electric loader movable arm coordination control method of the present application;

[0039] Figure 2 is a recognition flowchart of the working condition recognition model of the electric loader movable arm coordination control method of the present application. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present application clearer, the embodiments of the present application will be described in further detail below in combination with the drawings.

[0041] As shown in Figure 1 , first, the present application is generally introduced, and the research route of the electric loader movable arm coordination control method is as shown in Figure 1 , which specifically mainly includes the following steps:

[0042] Step 1, data acquisition input: various sensors are installed on the boom, bucket and walking driving part to collect data, collect relevant parameters of each part in working state, obtain real-time position of boom electric cylinder, output torque size, bucket displacement and turning angle size, force size at the hinge point connecting the boom and the bucket, walking gear position signal and torque size as data input of the system.

[0043] Step 2, boom coordination mode judge output: the collected data is subjected to a working condition identification model to obtain the working condition type of the electric loader, the coordination mode judge selects the boom coordination mode according to the working condition type and relying on the rules provided by the self-defined rule library, and outputs the boom coordination mode signal.

[0044] Step 3, boom synchronization controller outputs coordination signal: the boom synchronization controller calculates the error of the feedback signal according to the received boom coordination mode signal, and calculates and compensates in the coordination controller, and finally outputs the double-cylinder coordination control signal.

[0045] Step 4, boom electric cylinder execution and data feedback: the motor driver adjusts the output speed of the servo motor of the two-side boom electric cylinder according to the received double-cylinder coordination control signal, to drive the electric cylinder to output ideal displacement or torque size. At the same time, the displacement or torque data collected by the sensor installed at the end of the electric cylinder is fed back to the boom coordination controller to dynamically adjust the coordination control mode, so as to realize efficient coordinated movement between the two booms.

[0046] More specifically, the present application primarily performs data acquisition input to provide decision basis for subsequent working condition identification and coordination controller output. According to the data required for working condition identification model and boom position, torque double coordination mode dynamic switching, in step 1 above, a position sensor is used to collect real-time displacement of the boom and bucket electric cylinder; an angle sensor is used to collect the lifting angle of the boom and the turning angle of the bucket; a force sensor is used to collect the force at the hinge point connecting the bucket and the boom; a digital signal collector and a torque sensor are used to collect the gear position signal and walking torque of the walking driving.

[0047] Secondly, the coordination controller is the core module of the present application, mainly composed of working condition identification model, coordination mode judge, rule library and synchronization controller. The working condition identification model, coordination mode judge, rule library and synchronization controller are described in detail below.

[0048] The working condition of the electric loader is difficult to standardize, and the parameters collected at the working device are complex and redundant. Therefore, the present application selects the no-load forward, digging condition, full-load movement, unloading condition and no-load reverse as representative working condition categories according to the common V-shaped working mode of the electric loader, and constructs a working condition recognition model using the random forest algorithm.

[0049] The working condition recognition research route of the electric loader is as shown in Figure 2 First, the system collects the boom electric cylinder displacement, output torque size, bucket displacement and turning angle size, walking gear signal and torque size as feature input. Then, according to the feature input, the random forest algorithm is used to divide multiple sample data sets, and independent judgment is made through the constructed multiple decision tree classifiers. Finally, the current working condition type of the electric loader is accurately recognized through the algorithm voting mechanism.

[0050] Relying on the rule base and the working condition recognition model, a cooperative mode judge is designed, and the logical judgment rules of the judge are as follows:

[0051] (1)

[0052] The related parameters are defined as follows: is the cooperative mode signal, is the position cooperative mode signal, is the torque cooperative mode signal; , respectively correspond to the torque size of the left and right double booms, is defined as the maximum difference between the load torques of the left and right booms, which is used to judge whether the boom is in an unbalanced state; is the output displacement of the left boom electric cylinder, is the output displacement of the right boom electric cylinder, is defined as the maximum difference between the output displacements of the left and right boom electric cylinders, which is used to ensure the structural safety of the boom and the bucket.

[0053] The synchronous controller designs the cooperative controller using cross-coupling technology and PID control algorithm according to the received boom cooperative mode signal, and outputs the double-cylinder cooperative control signal in the corresponding boom cooperative mode.

[0054] 1. Position cooperative mode

[0055] The position cooperative mode requires that the output displacements of the two boom electric cylinders are real-time consistent, and the specific implementation steps are as follows:

[0056] Step1: Calculate the synchronization error of the output displacement of the two side boom electric cylinders according to the following formula 2 .

[0057] (2)

[0058] wherein: and are the output displacements of the left and right boom electric cylinders, respectively.

[0059] Step2: Design a synchronization controller using a PID control algorithm, and calculate the output compensation using the feedback synchronization error Finally, output the double-cylinder position coordination control signal according to the coefficient distribution method (formula 3).

[0060] (3)

[0061] wherein, , and are the three design coefficients of the PID control algorithm in the position coordination mode, and are the coupling coefficients of the left and right boom electric cylinders in the position coordination mode, calculated by formula 4 below, while satisfying the relationship + =1.

[0062] (4)

[0063] wherein: and are the output displacements of the left and right boom electric cylinders, respectively, is the ideal reference displacement of the left and right boom electric cylinders.

[0064] 2. Torque coordination mode

[0065] The common methods for collecting torque data are direct sensor collection and indirect torque calculation. The present application considers the disadvantages of low efficiency, easy damage and large error of directly installing a torque sensor on the boom electric cylinder, and uses a force sensor to collect the force at the hinge point connecting the bucket and the boom, and indirectly measures the load torque applied by the bucket to the boom through a torque calculation formula, as shown in formula 5 below.

[0066] (5)

[0067] wherein, is the collected force, is the force arm, i.e. the distance between the connecting hinge point and the boom electric cylinder.

[0068] The torque coordination mode requires that the output torque of the boom electric cylinder and the load torque borne by the boom are consistent. The specific implementation steps are as follows:

[0069] Step 1: Calculate the difference between the output torque of the electric cylinders on both sides of the boom and the load torque they bear in the torque coordination mode according to the following 6 .

[0070] (6)

[0071] in: is the output torque of the electric cylinders of the left and right booms, is the load torque of the left and right boom electric cylinders calculated by Equation 5.

[0072] Step 2: Use PID control algorithm to design synchronous controller and use the feedback synchronization difference Calculate and output the dual-cylinder torque coordinated control signal (Equation 7).

[0073] (7)

[0074] in, 、 and are the three design coefficients of the PID control algorithm in the torque coordination mode.

[0075] Although the present invention has been described above with reference to embodiments, various modifications may be made thereto and equivalent components may be substituted without departing from the scope of the present invention. In particular, as long as there are no structural conflicts, the various features of the embodiments disclosed herein may be combined with each other in any manner, and the omission of an exhaustive description of such combinations in this specification is solely for the sake of space and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for coordinated control of an electric-powered loader boom, characterized in that, The method comprises the following steps: S1, sensors are installed on the boom, bucket and walking driving part to collect data, including real-time position of the boom electric cylinder, output torque size, bucket displacement and turning angle size, force size at the hinge point connecting the boom and the bucket, walking gear signal and torque size data; S2, the collected data is subjected to a working condition recognition model to obtain the working condition type of the electric loader, a collaborative mode judging device selects the boom collaborative mode according to the working condition type and rules provided by a self-defined rule base, and outputs a boom collaborative mode signal; S3, a boom synchronous controller calculates the error of the feedback signal according to the received boom collaborative mode signal, and performs calculation and compensation in the collaborative controller, and finally outputs a double-cylinder collaborative control signal; S4, a motor driver adjusts the output speed of the servo motors of the two boom electric cylinders according to the received double-cylinder collaborative control signal, to drive the electric cylinders to output ideal displacement or torque size, and at the same time, real-time displacement or torque data collected by the sensors installed at the ends of the electric cylinders is fed back to the boom collaborative controller, to dynamically adjust the collaborative control mode, so as to realize efficient collaborative movement between the two booms.

2. The method of claim 1, wherein, In step S1, position sensors are used to collect the real-time displacement of the boom and bucket electric cylinders, angle sensors are used to collect the lifting angle of the boom and the turning angle of the bucket, force sensors are used to collect the force size at the hinge point connecting the bucket and the boom, and digital signal collectors and torque sensors are used to collect the gear signal and walking torque size of the walking driving.

3. The method of claim 1, wherein, In step S2, the specific steps of obtaining the working condition type of the electric loader through the working condition recognition model are as follows: the collected boom electric cylinder displacement, output torque size, bucket displacement and turning angle size, walking gear signal and torque size are input as features, then a plurality of sample data sets are divided by using a random forest algorithm, independent judgment is performed through a plurality of decision tree classifiers, and finally the working condition type of the current electric loader is accurately recognized through an algorithm voting mechanism.

4. The method of claim 1, wherein, In step S2, a collaborative mode judging device is designed relying on the rule base and the working condition recognition model, wherein the logical judgment rules of the judging device are as follows: ； wherein, is a position cooperative mode signal, is a position cooperative mode signal, is a torque cooperative mode signal; , respectively correspond to the torque of the left and right dual-arms, defined as the maximum difference of the load torque of the left and right arms, used to determine whether the arm is in an unbalanced state; is the output displacement of the left arm electric cylinder, is the output displacement of the right arm electric cylinder, defined as the maximum difference of the output displacement of the left and right arm electric cylinders, used to ensure the structural safety of the arm and the bucket.

5. The method of claim 1, wherein, In step S3, the synchronous controller designs the collaborative controller by using cross-coupling technology and PID control algorithm according to the received boom collaborative mode signal, and outputs the double-cylinder collaborative control signal in the corresponding boom collaborative mode, wherein the double-cylinder collaborative control signal in the boom collaborative mode includes a position collaborative mode and a torque collaborative mode.

6. The method of claim 5, wherein, The position collaborative mode requires that the output displacements of the two electric cylinders of the boom are consistent in real time, and the specific implementation steps are as follows: Step 1: Calculate the synchronization error of the output displacement of the two side boom electric cylinders according to the following formula wherein, ； wherein: and are the output displacements of the left and right boom electric cylinders, respectively. Step2: The PID control algorithm is used to design the synchronization controller, and the feedback synchronization error is used to adjust the synchronization controller The output compensation is calculated, and finally the double-cylinder position cooperative control signal is output according to the coefficient distribution method, and the formula is as follows: ； wherein, , and are three design coefficients of the PID control algorithm in the position coordination mode, and are the coupling coefficients of the left and right boom electric cylinders in the position coordination mode, which are calculated from the following formula, while satisfying the relationship + =1; ； wherein: and are the output displacements of the left and right boom electric cylinders, respectively, are the ideal reference displacements of the left and right boom electric cylinders.

7. The method of claim 5, wherein, The torque collaborative mode requires that the output torque of the boom electric cylinder and the load torque borne by the boom are consistent, and the specific implementation steps are as follows: Step 1: Calculate the difference between the output torque of the two side boom electric cylinders and the load torque they bear in the torque coordination mode according to the following formula ; ； wherein: is the output torque of the left and right side boom electric cylinders, is the load torque of the left and right side boom electric cylinders calculated by the following equation, ; ； wherein, is the force collected, is the arm of force, i.e. the distance between the hinge point and the boom electric cylinder. Step2: Design the synchronization controller by PID control algorithm, and use the feedback synchronization difference The output dual-cylinder torque coordination control signal is calculated, and the formula is as follows: ； in, 、 and are the three design coefficients of the PID control algorithm in the torque coordination mode.

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