A control method, device and computer readable storage medium of an electric counterbalance forklift truck

Abstract

This invention discloses a control method, device, and computer-readable storage medium for an electric counterbalance forklift. The method includes: after the controller receives the current speed and commanded speed of the electric counterbalance forklift, using the difference between the current speed and the commanded speed as an error speed, and calculating the current feedback control quantity based on the error speed; obtaining the current feedforward control quantity by querying a preset throttle speed data table based on the commanded speed; using the sum of the feedback control quantity and the feedforward control quantity as the current actual control quantity; outputting a braking signal with the maximum control quantity when the electric counterbalance forklift reaches the target position, and outputting a throttle signal with the actual control quantity when the electric counterbalance forklift has not reached the target position. This achieves a high-precision, low-latency control scheme for the electric counterbalance forklift, optimizing the multi-stage throttle and braking control mechanism of the electric counterbalance forklift.

Description

Technical Field

[0001] This invention relates to the field of electric forklift technology, and in particular to a control method, device and computer-readable storage medium for an electric counterbalance forklift. Background Technology

[0002] In the existing technology, for electric forklifts with throttle and braking systems, when the target speed of the electric forklift control point is known, the existing control methods are mainly of two types: one is to use machine learning to obtain the control quantities of throttle and brake; the other is to use a PID (Proportional Integral Derivative) controller to control throttle and brake.

[0003] However, the two types of solutions mentioned above have significant drawbacks when applied to the control of electric counterbalance forklifts (ACF): the former is based on machine learning and relies on a large amount of accurate known data, and it is difficult to find a suitable set of rules for electric counterbalance forklifts with large response delays, thus failing to meet the needs of all control scenarios; the latter, for electric counterbalance forklifts with large response delays, cannot track command speeds in a timely manner, resulting in poor curve tracking accuracy.

[0004] Therefore, how to provide a more precise control solution for current electric counterbalance forklifts has become an urgent technical problem to be solved. Summary of the Invention

[0005] To address the aforementioned technical deficiencies in the prior art, this invention proposes a control method for an electric counterbalance forklift, the method comprising:

[0006] After the controller receives the current speed and the commanded speed of the electric counterbalance forklift, it takes the difference between the current speed and the commanded speed as the error speed, and calculates the current feedback control quantity based on the error speed.

[0007] The controller retrieves the current feedforward control quantity from a preset throttle speed data table based on the commanded speed.

[0008] The sum of the feedback control quantity and the feedforward control quantity is taken as the current actual control quantity;

[0009] When the electric counterbalance forklift reaches the target position, a brake signal with the maximum control amount is output; when the electric counterbalance forklift has not reached the target position, a throttle signal with the actual control amount is output.

[0010] Optionally, the step of obtaining the current feedforward control quantity by querying a preset throttle speed data table based on the commanded speed by the controller includes:

[0011] Send multiple sets of throttle signals for control quantities to the electric counterbalance forklift;

[0012] After the electric counterbalance forklift stabilizes, multiple speed values ​​corresponding to the throttle signals of the multiple sets of control quantities are acquired, and the throttle speed data table is created based on the multiple sets of control quantities and the multiple sets of speed values.

[0013] Optionally, the step of outputting the throttle signal of the actual control quantity before the electric counterbalance forklift reaches the target position includes:

[0014] The preset starting mode of the electric counterbalance forklift;

[0015] The speed threshold of the preset start mode is set.

[0016] Optionally, the step of outputting the throttle signal of the actual control quantity before the electric counterbalance forklift reaches the target position includes:

[0017] The controller monitors the control points of the electric counterbalance forklift.

[0018] The feedback speed and target speed of the electric counterbalance forklift at the control point are obtained.

[0019] Optionally, the method further includes:

[0020] When the electric counterbalance forklift has not reached the target position, the magnitude relationship between the feedback speed and the target speed and the speed threshold is obtained;

[0021] When the feedback speed is less than the speed threshold and the target speed is greater than the speed threshold, the electric counterbalance forklift is determined to be in the starting mode.

[0022] Optionally, the method further includes:

[0023] The electric counterbalance forklift is preset with a first error threshold and a second error threshold in the starting mode, wherein the first error threshold is greater than the second error threshold;

[0024] The difference between the feedback speed and the target speed is taken as the speed error, and the relationship between the speed error and the first error threshold and / or the second error threshold is obtained.

[0025] Optionally, the method further includes:

[0026] Preset the first, second, and third scales from largest to smallest;

[0027] When the speed error is greater than the first error threshold, a throttle signal of the first proportion of the maximum throttle control amount is output; when the speed error is greater than the second error threshold and less than or equal to the first error threshold, a throttle signal of the second proportion of the maximum throttle control amount is output; when the speed error is less than or equal to the second error threshold, a throttle signal of the third proportion of the maximum throttle control amount is output.

[0028] Optionally, the step of outputting the throttle signal of the actual control quantity when the electric counterbalance forklift has not reached the target position includes:

[0029] When the feedback speed is greater than or equal to the speed threshold and the target speed is greater than the speed threshold, it is determined that the electric counterbalance forklift is in the normal mode after starting.

[0030] In the normal mode, if the electric counterbalance forklift does not reach the target position, the throttle signal of the actual control quantity is output.

[0031] The present invention also proposes a control device for an electric counterbalance forklift, the device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the control method for the electric counterbalance forklift as described in any of the preceding claims.

[0032] The present invention also proposes a computer-readable storage medium storing a control program for an electric counterbalance forklift, wherein the control program for the electric counterbalance forklift, when executed by a processor, implements the steps of the control method for the electric counterbalance forklift as described in any of the preceding claims.

[0033] The present invention discloses a control method, device, and computer-readable storage medium for an electric counterbalance forklift. After receiving the current speed and commanded speed of the electric counterbalance forklift, the controller uses the difference between the current speed and the commanded speed as an error speed and calculates the current feedback control quantity based on the error speed. The controller then retrieves the current feedforward control quantity from a preset throttle speed data table based on the commanded speed. The sum of the feedback control quantity and the feedforward control quantity is used as the current actual control quantity. When the electric counterbalance forklift reaches the target position, a braking signal with the maximum control quantity is output; when the electric counterbalance forklift has not reached the target position, a throttle signal with the actual control quantity is output. This achieves a high-precision, low-latency control scheme for an electric counterbalance forklift, optimizes the throttle and braking control mechanism of the electric counterbalance forklift in multiple stages, and improves the productivity of the electric counterbalance forklift. Attached Figure Description

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0035] Figure 1 This is the first flowchart of the control method for the electric counterbalance forklift of the present invention;

[0036] Figure 2 This is the second flowchart of the control method for the electric counterbalance forklift of the present invention;

[0037] Figure 3 This is the third flowchart of the control method for the electric counterbalance forklift of the present invention;

[0038] Figure 4 This is the fourth flowchart of the control method for the electric counterbalance forklift of the present invention;

[0039] Figure 5 This is the fifth flowchart of the control method for the electric counterbalance forklift of the present invention;

[0040] Figure 6 This is the sixth flowchart of the control method for the electric counterbalance forklift of the present invention;

[0041] Figure 7 This is the seventh flowchart of the control method for the electric counterbalance forklift of the present invention;

[0042] Figure 8 This is the eighth flowchart of the control method for the electric counterbalance forklift of the present invention;

[0043] Figure 9 This is a control principle diagram of the control method for the electric counterbalance forklift of the present invention;

[0044] Figure 10 This is a schematic diagram illustrating the throttle-speed relationship of the control method for the electric counterbalance forklift of the present invention. Detailed Implementation

[0045] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0046] In the following description, the use of suffixes such as "module," "part," or "unit" to denote elements is solely for the purpose of illustrative purposes and has no specific meaning in itself. Therefore, "module," "part," or "unit" may be used interchangeably.

[0047] Example 1

[0048] Figure 1 This is a flowchart of the first embodiment of the control method for an electric counterbalance forklift of the present invention. A control method for an electric counterbalance forklift, the method comprising:

[0049] S1. After the controller receives the current speed and the commanded speed of the electric counterbalance forklift, it takes the difference between the current speed and the commanded speed as the error speed, and calculates the current feedback control quantity based on the error speed.

[0050] S2. The controller retrieves the current feedforward control quantity from a preset throttle speed data table based on the commanded speed.

[0051] S3. The sum of the feedback control quantity and the feedforward control quantity is taken as the current actual control quantity;

[0052] S4. When the electric counterbalance forklift reaches the target position, output a brake signal with the maximum control amount; when the electric counterbalance forklift has not reached the target position, output a throttle signal with the actual control amount.

[0053] Please refer to Figure 9 In this context, Vel(i) represents the current command speed, PID Controller represents the controller, VelocityError represents the error speed, Feedforward represents the feedback control quantity, Car Model represents the vehicle mode, Position Reach represents the determination of whether the electric counterbalance forklift has reached the target position, Brake represents the brake, and Gas represents the throttle.

[0054] In this embodiment, if the current speed is V, and the controller receives an instruction to reach a speed Vel, the speed error (or error speed) Ve = V - Vel is calculated; Ve is processed by the PID controller to obtain the feedback control quantity uf; according to the preset throttle speed data table, the feedforward control quantity uff is obtained from Vel; the final control quantity u = uf + uff is calculated; at this time, if the vehicle reaches the target position, a braking signal is output, and the brake pedal is "pressed" to the bottom by outputting the braking signal with the maximum control quantity, controlling the vehicle to stop quickly; otherwise, the final control quantity u of the above throttle signal is output.

[0055] Specifically, in this embodiment, firstly, after the controller receives the current speed and commanded speed of the electric counterbalance forklift, the difference between the current speed and the commanded speed is used as the error speed, and the current feedback control quantity is calculated based on the error speed. Then, the controller queries a preset throttle speed data table based on the commanded speed to obtain the current feedforward control quantity. Next, the sum of the feedback control quantity and the feedforward control quantity is used as the current actual control quantity. Finally, when the electric counterbalance forklift reaches the target position, a brake signal with the maximum control quantity is output; when the electric counterbalance forklift has not reached the target position, a throttle signal with the actual control quantity is output. In this embodiment, the input quantities are the commanded speed and the actual speed of the drive wheels of the electric counterbalance forklift, and the output is the current throttle or brake control quantity. It can be seen that in this embodiment, by using an intelligent algorithm to control the throttle and brake pedals of the electric counterbalance forklift, the response and accuracy of the vehicle tracking the commanded speed are improved. Furthermore, through the above scheme, the longitudinal accuracy of the electric counterbalance forklift in position is within -4cm to 4cm. Among them, longitudinal positioning accuracy refers to the distance between the forklift control point and the final target position in the forklift's forward direction after the upper-level scheduling software gives a final target position.

[0056] Please refer to Figure 2 In this embodiment, the step of obtaining the current feedforward control quantity by querying a preset throttle speed data table based on the commanded speed by the controller includes:

[0057] S01. Send multiple sets of throttle signals for control quantities to the electric counterbalance forklift;

[0058] S02. After the electric counterbalance forklift speed stabilizes, acquire multiple speed values ​​corresponding to the throttle signals of the multiple sets of control quantities, and create the throttle speed data table based on the multiple sets of control quantities and the multiple sets of speed values.

[0059] Please refer to Figure 10 The x-axis represents the voltage value of the drive motor of the electric counterbalance forklift (in mV), and the y-axis represents the travel speed of the electric counterbalance forklift (in m / s). In this embodiment, multiple fixed sets of throttle control values ​​(1-100) are sent. After the speed of the electric counterbalance forklift stabilizes, the speed value of the electric counterbalance forklift is obtained. Thus, the speed value of the electric counterbalance forklift and the throttle control value correspond one-to-one, and the throttle speed data table of this embodiment is created accordingly.

[0060] Please refer to Figure 3 In this embodiment, before outputting the throttle signal of the actual control quantity when the electric counterbalance forklift has not reached the target position, the following steps are included:

[0061] S03. Preset the starting mode of the electric counterbalance forklift;

[0062] S04. Preset the speed threshold in the starting mode.

[0063] Please refer to Figure 4 In this embodiment, before outputting the throttle signal of the actual control quantity when the electric counterbalance forklift has not reached the target position, the following steps are included:

[0064] S05. Monitor the control points of the electric counterbalance forklift through the controller;

[0065] S06. Obtain the feedback speed and target speed of the electric counterbalance forklift at the control point.

[0066] Please refer to Figure 5 In this embodiment, the method further includes:

[0067] S51. When the electric counterbalance forklift has not reached the target position, obtain the relationship between the feedback speed and the target speed and the speed threshold, respectively.

[0068] S52. When the feedback speed is less than the speed threshold and the target speed is greater than the speed threshold, determine that the electric counterbalance forklift is in the starting mode.

[0069] Please refer to Figure 6 In this embodiment, the method further includes:

[0070] S53. A first error threshold and a second error threshold are preset for the electric counterbalance forklift in the starting mode, wherein the first error threshold is greater than the second error threshold;

[0071] S54. The difference between the feedback speed and the target speed is taken as the speed error, and the relationship between the speed error and the first error threshold and / or the second error threshold is obtained.

[0072] Please refer to Figure 7 In this embodiment, the method further includes:

[0073] S55, preset the first scale, second scale and third scale from large to small;

[0074] S56. When the speed error is greater than the first error threshold, output the throttle signal of the first proportional maximum throttle control amount; when the speed error is greater than the second error threshold and less than or equal to the first error threshold, output the throttle signal of the second proportional maximum throttle control amount; when the speed error is less than or equal to the second error threshold, output the throttle signal of the third proportional maximum throttle control amount.

[0075] In this embodiment, feedback is used as the vehicle's current feedback speed, reference as the vehicle's current target speed, and e as the speed error. This embodiment will use an early acceleration method to optimize the problem of large start-up delay in electric counterbalance forklifts. The specific strategy is as follows: when the current forklift control point speed feedback < 0.05 m / s and reference > 0.05 m / s, the start-up mode is entered, where e = reference - feedback. In the initial stage of the above start-up mode, the throttle control is increased to achieve rapid start-up. Wherein:

[0076] When e > 0.2, the output throttle gas = 100;

[0077] When e > 0.1, the output throttle gas = 100 * 0.9;

[0078] When e < 0.1, the output throttle gas = 100 * 0.8.

[0079] Please refer to Figure 8 In this embodiment, outputting the throttle signal of the actual control quantity when the electric counterbalance forklift has not reached the target position includes:

[0080] S41. When the feedback speed is greater than or equal to the speed threshold and the target speed is greater than the speed threshold, it is determined that the electric counterbalance forklift is in the normal mode after starting.

[0081] S42. In the normal mode, if the electric counterbalance forklift does not reach the target position, the throttle signal of the actual control quantity is output.

[0082] In this embodiment, during the travel phase after the start-up mode, normal control is performed according to the steps in the algorithm flow of the above embodiment.

[0083] As can be seen, in this embodiment, the control method of the electric counterbalance forklift differs from that of a typical automatic forklift. The ACF uses throttle and brakes to indirectly control vehicle speed, while a typical automatic forklift directly controls vehicle speed by controlling the motor's rotational speed. Therefore, this embodiment addresses the problem of excessive static response time in the ACF by predicting throttle advance during the start-up phase, thereby improving the speed tracking accuracy during the forklift's start-up. Furthermore, a speed feedforward + speed feedback control method is introduced, and the throttle-speed relationship table is calibrated, making the execution speed curve of the electric counterbalance forklift more closely match the command speed curve, further improving the speed control accuracy of the electric counterbalance forklift. Simultaneously, the longitudinal positioning error of the electric counterbalance forklift is kept within ±4cm.

[0084] The beneficial effects of this embodiment are as follows: after the controller receives the current speed and the commanded speed of the electric counterbalance forklift, it uses the difference between the current speed and the commanded speed as the error speed, and calculates the current feedback control quantity based on the error speed; the controller retrieves the current feedforward control quantity from a preset throttle speed data table based on the commanded speed; the sum of the feedback control quantity and the feedforward control quantity is used as the current actual control quantity; when the electric counterbalance forklift reaches the target position, a braking signal with the maximum control quantity is output; when the electric counterbalance forklift has not reached the target position, a throttle signal with the actual control quantity is output. This achieves a high-precision, low-latency electric counterbalance forklift control scheme, optimizes the throttle and braking control mechanism of the electric counterbalance forklift in multiple stages, and improves the productivity of the electric counterbalance forklift.

[0085] Example 9

[0086] Based on the above embodiments, the present invention also proposes a control device for an electric counterbalance forklift, the device including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the control method for the electric counterbalance forklift as described in any of the above embodiments.

[0087] It should be noted that the above-described device embodiments and method embodiments belong to the same concept. The specific implementation process can be found in the method embodiments, and the technical features in the method embodiments are also applicable to the device embodiments, which will not be repeated here.

[0088] Example 10

[0089] Based on the above embodiments, the present invention also proposes a computer-readable storage medium storing a control program for an electric counterbalance forklift, wherein the control program for the electric counterbalance forklift, when executed by a processor, implements the steps of the control method for the electric counterbalance forklift as described in any of the above embodiments.

[0090] It should be noted that the above-described medium embodiments and method embodiments belong to the same concept. The specific implementation process can be found in the method embodiments, and the technical features in the method embodiments are also applicable to the medium embodiments, which will not be repeated here.

[0091] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0092] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0093] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0094] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A control method for an electric counterbalance forklift, characterized in that, The method includes: After the controller receives the current speed and the commanded speed of the electric counterbalance forklift, it takes the difference between the current speed and the commanded speed as the error speed, and calculates the current feedback control quantity based on the error speed. The controller retrieves the current feedforward control quantity from a preset throttle speed data table based on the commanded speed. The sum of the feedback control quantity and the feedforward control quantity is taken as the current actual control quantity; When the electric counterbalance forklift reaches the target position, a brake signal with maximum control is output. When the electric counterbalance forklift has not reached the target position, a starting mode and a speed threshold in the starting mode are preset for the electric counterbalance forklift. The controller monitors the control point of the electric counterbalance forklift. The feedback speed and target speed of the electric counterbalance forklift at the control point are obtained. When the feedback speed is less than the speed threshold and the target speed is greater than the speed threshold, the electric counterbalance forklift is determined to be in the starting mode. When the feedback speed is greater than or equal to the speed threshold and the target speed is greater than the speed threshold, the electric counterbalance forklift is determined to be in the normal mode after starting. In the normal mode, a throttle signal with the actual control amount is output.

2. The control method for the electric counterbalance forklift according to claim 1, characterized in that, The step of obtaining the current feedforward control quantity by querying a preset throttle speed data table based on the commanded speed by the controller includes: Send multiple sets of throttle signals for control quantities to the electric counterbalance forklift; After the electric counterbalance forklift stabilizes, multiple speed values ​​corresponding to the throttle signals of the multiple sets of control quantities are acquired, and the throttle speed data table is created based on the multiple sets of control quantities and the multiple sets of speed values.

3. The control method for the electric counterbalance forklift according to claim 1, characterized in that, The method further includes: The electric counterbalance forklift is preset with a first error threshold and a second error threshold in the starting mode, wherein the first error threshold is greater than the second error threshold; The difference between the feedback speed and the target speed is taken as the speed error, and the relationship between the speed error and the first error threshold and / or the second error threshold is obtained.

4. The control method for the electric counterbalance forklift according to claim 3, characterized in that, The method further includes: Preset the first, second, and third scales from largest to smallest; When the speed error is greater than the first error threshold, a throttle signal of the first proportion of the maximum throttle control amount is output; when the speed error is greater than the second error threshold and less than or equal to the first error threshold, a throttle signal of the second proportion of the maximum throttle control amount is output; when the speed error is less than or equal to the second error threshold, a throttle signal of the third proportion of the maximum throttle control amount is output.

5. A control device for an electric counterbalance forklift, characterized in that, The device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the control method for the electric counterbalance forklift as described in any one of claims 1 to 4.

6. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a control program for an electric counterbalance forklift, which, when executed by a processor, implements the steps of the control method for an electric counterbalance forklift as described in any one of claims 1 to 4.

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