Cooperative control method for movable arm of electric loader

Abstract

The invention discloses a cooperative control method for a movable arm of an electric loader in the technical field of electric control of engineering machinery. The method comprises the following steps that the real-time position of a movable arm electric cylinder, the output torque, the displacement and turning angle of a bucket, the stress at the connecting hinge point of the movable arm and the bucket, a walking gear signal and the torque of the walking gear signal are collected, the collected data are processed through a working condition recognition model to obtain the working condition type of the electric loader, and a cooperative mode judging device judges the working condition of the electric loader according to the working condition type. Meanwhile, a movable arm cooperation mode is selected according to rules provided by a user-defined rule base, a movable arm cooperation mode signal is output, a movable arm synchronous controller outputs a double-cylinder cooperation control signal, and a motor driver adjusts the output rotating speed of movable arm electric cylinder servo motors on the two sides according to the received movable arm cooperation control signal; the electric cylinders are driven to output ideal displacement or torque, efficient cooperative control over the movable arm electric cylinders on the two sides of the electric loader is achieved, and the operation safety and the operation efficiency of a working device of the electric loader are improved.

Description

Technical Field

[0001] The invention relates to the technical field of electric control of engineering machinery, and in particular to a method for coordinated control of an electric loader boom. Background Art

[0002] As an important machine model in the existing engineering field, loaders are widely used in key tasks such as mining transportation and urban construction, but traditional fuel loaders have serious carbon emission problems. With the increasing consumption of traditional energy and the increasing prominence of environmental problems, the electrification upgrade of loaders has become an important measure for my country 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, an independent motor drive system is configured for each wheel 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 the operation, the working device has not yet achieved pure electrification and still retains the traditional hydraulic drive mode. Compared with the pure electric drive mode, this traditional hydraulically driven working device adopts a multi-stage transmission mode of "power source-pump oil supply-valve flow distribution", which leads to step-by-step energy loss during the transmission process and low energy utilization. At the same time, the inherent strong nonlinear characteristics of the working device hydraulic system, complex dynamic response, and control accuracy are also difficult to meet the future work device efficient unmanned operation requirements. Therefore, it is urgent to upgrade the loader's working device to electrification to achieve full electrification of the loader.

[0003] The working device of an electric loader is mainly divided into two parts: the boom and the bucket. Since the boom system has electric cylinders on both sides, the main difficulty in the electric control of the loader working device is how to synchronously control the electric cylinders on both sides of the boom system. At present, some studies have tried to adopt a position coordination control strategy to keep the output displacement of the boom electric cylinder consistent and achieve coordination of the booms on both sides under normal working conditions. However, the complex cyclic working conditions of the loader will lead to frequent eccentric loading. This single position coordination mode cannot effectively deal with the unbalanced state caused by severe eccentric loading, which will lead to imbalance and damage of the boom structure, seriously affecting the operating safety of the electric loader working device. At the same time, this single position coordination mode lacks attention to the output torque of the boom electric cylinder. Therefore, in the case of eccentric loading, the boom electric cylinder on the lighter load side will produce excess torque output, resulting in torque loss of the boom electric cylinder and reducing the energy utilization efficiency of the electric loader working device. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] Therefore, the purpose of the present invention is to provide a method for coordinated control of the boom of an electric loader, which realizes efficient coordinated control of the electric cylinders of the booms on both sides of the electric loader and improves the operating 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 invention, the present invention provides the following technical solutions: A method for coordinated control of an electric loader boom, comprising: S1. Install sensors on the boom, bucket and travel drive part to collect data, including the real-time position of the boom electric cylinder, output torque, bucket displacement and flip angle, force at the hinge point between the boom and bucket, travel gear signal and torque data; S2. The collected data is passed through the working condition identification model to obtain the working condition type of the electric loader. The collaborative mode determiner selects the boom collaborative mode based on the working condition type and the rules provided by the custom rule library, and outputs the boom collaborative mode signal; S3, the boom synchronization controller calculates the error of the feedback signal according to the received boom coordination mode signal, and performs calculation and compensation in the coordination controller, and finally outputs the dual-cylinder coordination control signal; S4. The motor driver adjusts the output speed of the servo motors of the electric cylinders of the booms on both sides according to the received boom cooperative control signal to drive the electric cylinders to output the ideal displacement or torque. At the same time, the sensor installed at the end of the electric cylinder is used to collect displacement or torque data in real time and feed it back to the boom cooperative controller to dynamically adjust the cooperative control mode, thereby realizing efficient cooperative movement between the booms on both sides.

[0007] As a preferred scheme of the coordinated control method of the boom of an electric loader described in the present invention, in step S1, position sensors are used to collect the real-time displacement of the boom and the bucket electric cylinder, angle sensors are used to collect the lifting angle of the boom and the flip angle of the bucket, force sensors are used to collect the force at the hinge point between the bucket and the boom, and digital signal collectors and torque sensors are used to collect the gear signal of the walking drive and the walking torque.

[0008] As a preferred scheme of the electric loader boom coordinated control method described in the present invention, in step S2, the specific steps of obtaining the electric loader working condition type through the working condition identification model using the collected data are as follows: the collected boom electric cylinder displacement, output torque, bucket displacement and flip angle, travel gear signal and torque are used as feature inputs, and then, according to the feature inputs, a random forest algorithm is used to divide multiple sample data sets, and independent judgments are made through the constructed multiple decision tree classifiers, and finally, the algorithm voting mechanism is used to accurately identify the current electric loader working condition type.

[0009] As a preferred solution of the electric loader boom coordinated control method of the present invention, in step S2, a coordinated mode judge is designed based on a rule base and a working condition identification model, wherein the logical judgment rules of the judge are as follows: ; in, is the collaborative mode signal, is the location coordination mode signal, is the torque coordination mode signal; , The torque corresponding to the left and right double booms, It is defined as the maximum difference between the load torque of the left and right booms, and is used to determine whether the boom is in an eccentric load state; is the output displacement of the left boom electric cylinder, is the output displacement of the right boom electric cylinder, It is defined as the maximum difference in output displacement of the electric cylinders of the left and right booms, to ensure the structural safety of the boom and bucket.

[0010] As a preferred scheme of the electric loader boom cooperative control method described in the present invention, in step S3, the synchronous controller designs the cooperative controller according to the received boom cooperative mode signal by using cross-coupling technology and PID control algorithm, and outputs the dual-cylinder cooperative control signal under the corresponding boom cooperative mode, and the dual-cylinder cooperative control signal under the boom cooperative mode includes a position cooperative mode and a torque cooperative mode.

[0011] As a preferred solution of the electric loader boom coordinated control method of the present invention, the position coordination mode requires that the output displacement of the electric cylinders on both sides of the boom remain consistent in real time, and the specific implementation steps are as follows: Step 1: Calculate the synchronous error of the output displacement of the electric cylinders of the two sides of the boom according to the following formula ,in, ; in: and They are the output displacements of the left and right boom electric cylinders respectively; Step 2: Use PID control algorithm to design synchronization controller and use feedback synchronization error Calculate the output compensation, and finally output the dual-cylinder position coordinated control signal according to the coefficient allocation method. The formula is as follows: ; in, , and are the three design coefficients of the PID control algorithm in the position coordination mode, and is the coupling coefficient of the left and right boom electric cylinders in the position coordination mode, which is calculated by the following formula and satisfies the relationship + =1; ; in: and are the output displacements of the left and right boom electric cylinders, It is the ideal reference displacement of the left and right boom electric cylinders.

[0012] As a preferred solution of the electric loader boom coordinated control method of the present invention, the torque coordination 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 electric cylinders on both sides of the boom and the load torque they bear in the torque coordination mode according to the following formula ; ; in: is the output torque of the electric cylinders of the left and right booms, is the load torque of the electric cylinders of the left and right booms calculated by the following formula, ; ; in, is the collected force, is the lever arm, i.e. the distance between the connection hinge and the electric cylinder of the boom; Step 2: Use PID control algorithm to design synchronous controller and use the feedback synchronization difference Calculate the output dual-cylinder torque coordinated control signal, the formula is as follows: ; in, , and are the three design coefficients of the PID control algorithm in the torque coordination mode.

[0013] Compared with the prior art, the present invention has the following beneficial effects: the present invention comprehensively considers the position coordination and torque coordination modes of the loader boom electric cylinder, establishes a dynamic switching mechanism between position coordination and torque coordination under different operating conditions and degrees of unbalanced load, overcomes the structural imbalance and energy loss problems of the loader boom system under a single position coordination control mode, realizes efficient coordinated control of the boom electric cylinders on both sides of the electric loader, and improves the operating safety and efficiency of the electric loader working device. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below in combination with the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them: Figure 1 It is a flow chart of a method for coordinated control of an electric loader boom according to the present invention; Figure 2 The present invention discloses an identification flow chart of an operating condition identification model of an electric loader boom cooperative control method. DETAILED DESCRIPTION

[0015] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0016] like Figure 1 As shown, the present invention is first generally introduced. The research route of the electric loader boom coordinated control method is as follows: Figure 1 As shown, the specific steps mainly include: Step 1, data acquisition input: various sensors are installed on the boom, bucket and travel drive parts for data acquisition, and the relevant parameters of each part under the working state are collected to obtain the real-time position of the boom electric cylinder, the output torque, the bucket displacement and flip angle, the force at the hinge point between the boom and the bucket, the travel gear signal and its torque as the data input of the system.

[0017] Step 2, boom coordination mode determiner determines output: the collected data is passed through the working condition identification model to obtain the working condition type of the electric loader. The coordination mode determiner selects the boom coordination mode based on the working condition type and the rules provided by the custom rule library, and outputs the boom coordination mode signal.

[0018] Step 3, the boom synchronization controller outputs a coordination signal: the boom synchronization controller calculates the error of the feedback signal according to the received boom coordination mode signal, and performs calculation and compensation in the coordination controller, and finally outputs a dual-cylinder coordination control signal.

[0019] Step 4, boom electric cylinder execution and data feedback: The motor driver adjusts the output speed of the boom electric cylinder servo motors on both sides according to the boom coordinated control signal received to drive the electric cylinder to output the ideal displacement or torque. At the same time, the displacement or torque data is collected in real time by the sensor installed at the end of the electric cylinder, and fed back to the boom coordinated controller to dynamically adjust the coordinated control mode, thereby achieving efficient coordinated movement between the booms on both sides.

[0020] More specifically, the present invention first performs data acquisition input to provide a decision-making basis for subsequent working condition identification and collaborative controller output, based on the working condition identification model and the data requirements for dynamic switching of the boom position and torque dual collaborative modes. To this end, in the above step 1, position sensors are used to collect the real-time displacement of the boom and bucket electric cylinder respectively; angle sensors are used to collect the lifting angle of the boom and the flip angle of the bucket; force sensors are used to collect the force at the hinge point where the bucket and the boom are connected; and digital signal collectors and torque sensors are used to collect the gear signal of the walking drive and the walking torque.

[0021] Secondly, the collaborative controller, as the core module of the present invention, is mainly composed of a working condition identification model, a collaborative mode judge, a rule base and a synchronous controller. The working condition identification model, the collaborative mode judge, the rule base and the synchronous controller are introduced in detail below.

[0022] At present, the working environment of electric loaders is complex and changeable, the load changes greatly in the cycle working conditions, and the working methods are diverse, which makes it difficult to formulate the working condition standards of electric loaders and the parameters collected at the working device are complex and redundant. Therefore, based on the "V"-shaped working mode of common electric loaders and combined with the actual application background of the present invention, the present invention selects no-load forward, shovel working condition, full-load moving, unloading working condition and no-load reverse as representative working condition categories, and uses the random forest algorithm to construct a working condition recognition model.

[0023] Research routes for electric loader operating condition identification Figure 2 As shown in the figure, first, the system takes the collected boom electric cylinder displacement, output torque, bucket displacement and flip angle, travel gear signal and torque as feature input. Then, according to the feature input, the random forest algorithm is used to divide multiple sample data sets, and independent judgments are made through the constructed multiple decision tree classifiers. Finally, the algorithm voting mechanism is used to accurately identify the current working condition type of the electric loader.

[0024] Relying on the rule base and working condition identification model, a collaborative mode judge is designed, where the logical judgment rules of the judge are as follows: (1) The relevant parameters are defined as follows: is the collaborative mode signal, is the location coordination mode signal, is the torque coordination mode signal; , The torque corresponding to the left and right double booms, It is defined as the maximum difference between the load torque of the left and right booms, and is used to determine whether the boom is in an eccentric load state; is the output displacement of the left boom electric cylinder, is the output displacement of the right boom electric cylinder, It is defined as the maximum difference in output displacement of the electric cylinders of the left and right booms, to ensure the structural safety of the boom and bucket.

[0025] According to the received boom cooperative mode signal, the synchronous controller uses cross-coupling technology and PID control algorithm to design the cooperative controller, and outputs the dual-cylinder cooperative control signal under the corresponding boom cooperative mode.

[0026] 1. Location Collaboration Mode The position coordination mode requires that the output displacement of the electric cylinders on both sides of the boom remain consistent in real time. The specific implementation steps are as follows: Step 1: Calculate the synchronous error of the output displacement of the electric cylinders of the two sides of the boom according to the following formula 2 .

[0027] (2) in: and They are the output displacements of the left and right boom electric cylinders respectively.

[0028] Step 2: Use PID control algorithm to design synchronization controller and use feedback synchronization error Calculate the output compensation, and finally output the dual-cylinder position coordinated control signal according to the coefficient allocation method (Formula 3).

[0029] (3) in, , and are the three design coefficients of the PID control algorithm in the position coordination mode, and is the coupling coefficient of the left and right boom electric cylinders in the position coordination mode, which is calculated by the following formula 4 and satisfies the relationship + =1.

[0030] (4) in: and are the output displacements of the left and right boom electric cylinders, It is the ideal reference displacement of the left and right boom electric cylinders.

[0031] 2. Torque coordination mode Common methods for collecting torque data include direct sensor collection and indirect torque calculation. The present invention comprehensively considers the shortcomings of directly installing a torque sensor on the boom electric cylinder, such as low efficiency, easy damage and large errors. A force sensor is used to collect the force at the hinge point between the bucket and the boom, and the load torque applied by the bucket to the boom is indirectly calculated through the torque calculation formula, as shown in Formula 5 below.

[0032] (5) in, is the collected force, The lever arm is the distance between the hinge point and the boom electric cylinder.

[0033] The torque coordination mode requires that the output torque of the boom electric cylinder and the load torque borne by the boom be consistent. The specific implementation steps are as follows: Step 1: Calculate the difference between the output torque of the electric cylinders of the two arms and the load torque they bear in the torque coordination mode according to the following 6 .

[0034] (6) in: is the output torque of the electric cylinders of the left and right booms, is the load torque of the electric cylinders of the left and right booms calculated by equation 5.

[0035] Step 2: Use PID control algorithm to design synchronous controller and use the feedback synchronization difference Calculate and output the dual-cylinder torque cooperative control signal (Equation 7).

[0036] (7) in, , and are the three design coefficients of the PID control algorithm in the torque coordination mode.

[0037] Although the present invention has been described above with reference to the embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed in the present invention may be used in combination with each other in any manner, and the fact that these combinations are not exhaustively described in this specification is only for the sake of omitting space and saving resources. 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 loader boom, characterized in that: include: S1. Install sensors on the boom, bucket and travel drive part to collect data, including the real-time position of the boom electric cylinder, output torque, bucket displacement and flip angle, force at the hinge point between the boom and bucket, travel gear signal and torque data; S2. The collected data is passed through the working condition identification model to obtain the working condition type of the electric loader. The collaborative mode determiner selects the boom collaborative mode based on the working condition type and the rules provided by the custom rule library, and outputs the boom collaborative mode signal; S3, the boom synchronization controller calculates the error of the feedback signal according to the received boom coordination mode signal, and performs calculation and compensation in the coordination controller, and finally outputs the dual-cylinder coordination control signal; S4. The motor driver adjusts the output speed of the servo motors of the electric cylinders of the booms on both sides according to the received boom cooperative control signal to drive the electric cylinders to output the ideal displacement or torque. At the same time, the sensor installed at the end of the electric cylinder is used to collect displacement or torque data in real time and feed it back to the boom cooperative controller to dynamically adjust the cooperative control mode, thereby realizing efficient cooperative movement between the booms on both sides.

2. The electric loader boom coordinated control method according to claim 1, characterized in that: In step S1, position sensors are used to collect the real-time displacement of the boom and bucket electric cylinder, angle sensors are used to collect the lifting angle of the boom and the flip angle of the bucket, force sensors are used to collect the force at the hinge point between the bucket and the boom, and digital signal collectors and torque sensors are used to collect the gear signal of the walking drive and the walking torque.

3. The electric loader boom coordinated control method according to claim 1, characterized in that: In step S2, the specific steps of obtaining the working condition type of the electric loader by passing the collected data through the working condition identification model are as follows: the collected boom electric cylinder displacement, output torque, bucket displacement and flip angle, travel gear signal and torque are used as feature inputs, and then, according to the feature inputs, a random forest algorithm is used to divide multiple sample data sets, and independent judgments are made through the constructed multiple decision tree classifiers, and finally, the working condition type of the current electric loader is accurately identified through the algorithm voting mechanism.

4. The method for coordinated control of an electric loader boom according to claim 1, characterized in that: In step S2, a collaborative mode judge is designed based on the rule base and the working condition identification model, wherein the logical judgment rules of the judge are as follows: ； in, is the collaborative mode signal, is the location coordination mode signal, is the torque coordination mode signal; , The torque corresponding to the left and right double booms, It is defined as the maximum difference between the load torque of the left and right booms, and is used to determine whether the boom is in an eccentric load state; is the output displacement of the left boom electric cylinder, is the output displacement of the right boom electric cylinder, It is defined as the maximum difference in output displacement of the electric cylinders of the left and right booms, to ensure the structural safety of the boom and bucket.

5. The electric loader boom coordinated control method according to claim 1, characterized in that: In step S3, the synchronous controller designs a collaborative controller using cross-coupling technology and PID control algorithm according to the received boom collaborative mode signal, and outputs a dual-cylinder collaborative control signal under the corresponding boom collaborative mode, wherein the dual-cylinder collaborative control signal under the boom collaborative mode includes a position collaborative mode and a torque collaborative mode.

6. The electric loader boom coordinated control method according to claim 5, characterized in that: The position coordination mode requires that the output displacement of the electric cylinders on both sides of the boom remain consistent in real time. The specific implementation steps are as follows: Step 1: Calculate the synchronous error of the output displacement of the electric cylinders of the two sides of the boom according to the following formula ,in, ； in: and They are the output displacements of the left and right boom electric cylinders respectively; Step 2: Use PID control algorithm to design synchronization controller and use feedback synchronization error Calculate the output compensation, and finally output the dual-cylinder position coordinated control signal according to the coefficient allocation method. The formula is as follows: ； in, , and are the three design coefficients of the PID control algorithm in the position coordination mode, and is the coupling coefficient of the left and right boom electric cylinders in the position coordination mode, which is calculated by the following formula and satisfies the relationship + =1; ； in: and are the output displacements of the left and right boom electric cylinders, It is the ideal reference displacement of the left and right boom electric cylinders.

7. The electric loader boom coordinated control method according to claim 5, characterized in that: 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: 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 formula ; ； in: is the output torque of the electric cylinders of the left and right booms, is the load torque of the electric cylinders of the left and right booms calculated by the following formula, ; ； in, is the collected force, is the lever arm, i.e. the distance between the connection hinge and the electric cylinder of the boom; Step 2: Use PID control algorithm to design synchronous controller and use the feedback synchronization difference Calculate the output dual-cylinder torque coordinated control signal, 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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