A control method, device and medium of a swing motor of an excavator

Abstract

The application discloses a control method, device and medium of a revolving motor of an excavator, and the method comprises the following steps: determining a revolving action of the excavator, controlling a hydraulic pump of the excavator according to the revolving action, so that the hydraulic pump current is executed according to a first slope set in advance; determining a preset overflow pressure, determining a control current according to the overflow pressure; determining a preset current target value and a preset acceleration time, determining a second slope according to the control current, the current target value and the acceleration time, and controlling the hydraulic pump, so that the hydraulic pump current is executed according to the second slope. When the revolving action is started, the current slope of the overflow stage of the revolving motor is matched and controlled, the overflow loss of the revolving overflow valve is reduced, the energy-saving control in the accelerating stage of the single revolving action is realized, the control performance is not affected, and the method has the advantages of economy, practicability and reliability, and is convenient to implement in the electric control system of the excavator.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of computers, and particularly relates to a control method and device for a rotary motor of a excavator and a medium. BACKGROUND

[0002] Hydraulic excavators are widely used in various construction fields, and the hydraulic excavator has the disadvantage of high oil consumption. How to improve the energy utilization efficiency of the excavator has always been the focus of relevant technical personnel and has always been a difficult technical problem to overcome. When the hydraulic excavator is braked, due to the large inertia of the rotating platform, the rotary motor will not stop rotating immediately, it will continue to rotate and compress the oil at the oil outlet, so that the rotary motor oil outlet generates instantaneous high-pressure oil, and the oil is overflowed from the overflow valve. In this process, the kinetic energy of the rotating platform is converted into the heat energy of the oil, so as to achieve the purpose of braking the rotating platform. In a typical working cycle of the excavator, the rotary motor needs to be started and braked twice. Under long-time work, the energy wasted by the rotary motor braking overflow is very large. SUMMARY

[0003] In order to solve the above problems, the present application provides a control method for a rotary motor of a excavator, comprising: determining a rotary action of the excavator, controlling a hydraulic pump of the excavator according to the rotary action, so that the hydraulic pump current is executed according to a first slope set in advance; determining a pre-set overflow pressure, determining a control current according to the overflow pressure; determining a pre-set current target value and a pre-set acceleration time, determining a second slope according to the control current, the current target value and the acceleration time, and controlling the hydraulic pump so that the hydraulic pump current is executed according to the second slope.

[0004] In one example, the control current is determined according to the overflow pressure, specifically comprising: determining the overflow pressure by the controller of the excavator, judging the pressure of the hydraulic pump according to the overflow pressure; if the pressure of the hydraulic pump is equal to the overflow pressure, the current value corresponding to the pressure is determined to determine the control current.

[0005] In one example, the second slope is determined according to the control current, the current target value and the acceleration time, specifically comprising: the calculation formula of the second slope is:

[0006]

[0007] Wherein, Ramp2 is the second slope, iPumpGoal is the current target value, iPumpStart is the control current, and T is the acceleration time.

[0008] In one example, after the hydraulic pump current is executed according to the second slope, the method further comprises: acquiring the hydraulic pump current in real time by the controller of the excavator, and judging the hydraulic pump current according to the current target value; if the hydraulic pump current is equal to the current target value, the hydraulic pump is controlled to keep the hydraulic pump current.

[0009] In one example, determining the swing action of the excavator specifically comprises: determining a handle operation signal of the excavator, and transmitting the handle operation signal to the controller of the excavator; receiving the handle operation signal by the controller, and determining the swing action of the excavator according to the handle operation signal.

[0010] In one example, before the hydraulic pump of the excavator is controlled according to the swing action, the method further comprises: starting the hydraulic pump according to the handle operation signal to increase the hydraulic pump current from an initial current, wherein the initial current is 0.

[0011] In one example, determining the pre-set current target value specifically comprises: determining a motor displacement of the hydraulic pump, and determining a motor output speed corresponding to the swing action, determining an output flow of the hydraulic pump according to the motor displacement and the motor output speed, and determining the current target value according to the output flow of the hydraulic pump.

[0012] In one example, determining the pre-set acceleration time specifically comprises: determining a first time point when the pressure of the hydraulic pump is equal to the overflow pressure; determining a swing time according to the swing action, and determining a second time point according to the swing time; determining the difference between the second time point and the first time point to determine the acceleration time.

[0013] On the other hand, the application also proposes a control device of an excavator swing motor, comprising: at least one processor; and a memory in communication connection with the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the control device of the excavator swing motor to perform: determining a swing action of an excavator, controlling a hydraulic pump of the excavator according to the swing action to execute a hydraulic pump current according to a pre-set first slope; determining a pre-set overflow pressure, determining a control current according to the overflow pressure; determining a pre-set current target value and a pre-set acceleration time, determining a second slope according to the control current, the current target value and the acceleration time, and controlling the hydraulic pump to execute the hydraulic pump current according to the second slope.

[0014] In another aspect, the application also provides a non-volatile computer storage medium, which stores computer executable instructions configured to determine a slewing action of an excavator, control a hydraulic pump of the excavator according to the slewing action, so that a hydraulic pump current is executed according to a first preset slope; determine a preset relief pressure, determine a control current according to the relief pressure; determine a preset current target value and a preset acceleration time, determine a second slope according to the control current, the current target value and the acceleration time, and control the hydraulic pump so that the hydraulic pump current is executed according to the second slope.

[0015] The application matches and controls the current slope of the overflow stage of the slewing motor when the slewing action is started, reduces the overflow loss of the slewing overflow valve under the premise of ensuring the overflow pressure, realizes the energy-saving control of the slewing single-action acceleration stage, has no influence on the operation, and has economy, practicability and reliability, and is convenient to implement in the excavator electric control system. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which are included to provide a further understanding of the application and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

[0017] Figure 1 FIG. 1 is a flowchart of a control method of a slewing motor of an excavator according to an embodiment of the application;

[0018] Figure 2 FIG. 4 is a schematic diagram of the change of the hydraulic pump current according to an embodiment of the application;

[0019] Figure 3 FIG. 5 is a schematic diagram of the change of the pump pressure according to an embodiment of the application;

[0020] Figure 4 FIG. 6 is a schematic diagram of a control device of a slewing motor of an excavator according to an embodiment of the application. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the application clearer, the technical scheme of the application will be described in detail below with reference to the embodiments of the application and the corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0022] The technical scheme provided by each embodiment of the application will be described in detail below with reference to the drawings.

[0023] In the hydraulic pump current, that is, the hydraulic pump output flow and the swing motor demand flow matching process, the pump output flow is often too much, causing the swing motor overflow flow loss, causing resource waste, poor economy.

[0024] As shown in Figure 1 To solve the above problems, the control method of the excavator swing motor provided by the embodiments of the application, the method comprises:

[0025] S101, determine the swing action of the excavator, control the hydraulic pump of the excavator according to the swing action, so that the hydraulic pump current is executed according to the first slope set in advance.

[0026] The application is based on the circuit of the hydraulic pump controlling the swing motor in the hydraulic system of the excavator, the hydraulic pump current control is the main control object, and the output pressure of the hydraulic pump and the handle operation signal are the main input signals.

[0027] The controller determines whether the current is a swing operation according to the handle operation signal. If the swing operation is performed, the hydraulic pump current iPump is controlled to increase according to the initial slope Ramp1 (referred to as the first slope herein). The initial slope Ramp1 is a calibratable variable, which represents the initial current change rate of the hydraulic pump when starting to execute. The larger the corresponding value is, the more "shocking" the swing operation starting feeling is; the smaller the corresponding value is, the more "soft" the swing operation starting feeling is. The larger the current is, the faster the hydraulic pump pressure building process is.

[0028] S102, determine the pre-set relief pressure, and determine the control current according to the relief pressure.

[0029] The controller determines whether the pump pressure pPump is equal to the relief pressure pRelief of the swing motor relief valve. If not, the process of S101 is continued. If yes, the current iPump (referred to as the control current herein) when pPump=PRelief is obtained, which is denoted as iPumpStart. At this time, the hydraulic pressure reaches the swing motor relief pressure. The relief pressure pRelief of the motor relief valve can be flexibly matched according to the parameters of different types of relief valves, which is a calibratable variable.

[0030] S103, determine the pre-set current target value and the pre-set acceleration time, determine the second slope according to the control current, the current target value and the acceleration time, and control the hydraulic pump so that the hydraulic pump current is executed according to the second slope

[0031] The hydraulic pump current iPump continues to increase, executing a new ramp rate, Ramp2 (herein referred to as the second ramp). The swing acceleration phase is considered complete when the hydraulic pump current iPump reaches the target hydraulic pump current iPumpGoal. The target hydraulic pump current iPumpGoal is determined based on the required swing motor speed and can be tailored to different speed requirements. A higher target current value indicates a higher speed.

[0032] In one embodiment, the calculation formula of the second slope is:

[0033]

[0034] Here, Ramp2 is the second slope, iPumpGoal is the target current value, iPumpStart is the control current, and T is the acceleration time. T is determined based on the desired acceleration experience during the acceleration phase. A larger value results in a smaller Ramp2, resulting in a stronger acceleration sensation, but also less significant energy savings. This value can be adjusted flexibly based on debugging needs.

[0035] In one embodiment, an excavator has a required swing motor speed. This requirement is closely related to the hydraulic pump's output flow rate, as shown by the relationship: Hydraulic Motor Output Speed ​​= Hydraulic Pump Output Flow Rate / Hydraulic Motor Displacement, where hydraulic motor displacement is a physical characteristic of the hydraulic motor. Therefore, hydraulic pump output flow rate = engine speed × hydraulic pump control current. Therefore, when the engine speed is constant, a higher hydraulic pump control current means a higher swing motor output speed. Therefore, the hydraulic pump target current iPumpGoal is the target hydraulic pump current value required to meet the required hydraulic motor output speed. The specific value needs to be determined based on the specific excavator requirements.

[0036] In one embodiment, a higher pump current results in a steeper ramp, which translates to faster and more aggressive swing acceleration. However, for excavators, faster isn't always better; a certain degree of compliance is necessary. Therefore, adjusting the current slope Ramp1 adjusts the acceleration sensation during the initial phase of the movement. When the pump pressure reaches the swing motor overflow pressure, the pump current at that point is directly defined as the hydraulic pump control current iPumpStart. With the hydraulic pump target current iPumpGoal pre-set, only T needs to be adjusted. A larger T results in slower second-stage acceleration, while a smaller T results in faster second-stage acceleration, thus achieving two-stage acceleration control. For example, the swing time is determined based on the actual swing speed, and T is then determined based on the swing time. When the hydraulic pump pressure equals the overflow pressure, the corresponding first time point is determined. The swing time is determined based on the swing movement, and the second time point is determined based on the swing time. The difference between the second time point and the first time point is determined to determine the acceleration time.

[0037] As Figure 2 shown, before the pump pressure pPump = PRelief, the pump current iPump increases with a slope Ramp1 until pPump = PRelief is met, as Figure 3 shown, note the iPump at this time as iPumpStart, and the pump current iPump executes a new slope Ramp2 until iPump = iPumpGoal, at which point the current is held constant.

[0038] In one embodiment, the hydraulic pump is started according to the handle operation signal, so that the hydraulic pump current increases from an initial current, wherein the initial current is 0.

[0039] In one embodiment, the relief pressure is determined by the controller of the excavator, and the pressure of the hydraulic pump is determined according to the relief pressure; if the pressure of the hydraulic pump is equal to the relief pressure, the current value corresponding to the pressure is determined to determine the control current.

[0040] In one embodiment, the handle operation signal of the excavator is determined, and the handle operation signal is transmitted to the controller of the excavator; the handle operation signal is received by the controller, and the slewing action of the excavator is determined according to the handle operation signal.

[0041] As Figure 4 shown, the embodiment of the present application also provides a control device of an excavator slewing motor, comprising:

[0042] at least one processor; and,

[0043] a memory in communication connection with the at least one processor; wherein,

[0044] The memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable a control device of an excavator slewing motor to perform:

[0045] determine the slewing action of the excavator, and control the hydraulic pump of the excavator according to the slewing action, so that the hydraulic pump current is executed according to a first slope set in advance;

[0046] determine a relief pressure set in advance, and determine a control current according to the relief pressure;

[0047] determine a current target value set in advance and an acceleration time set in advance, determine a second slope according to the control current, the current target value and the acceleration time, and control the hydraulic pump so that the hydraulic pump current is executed according to the second slope.

[0048] The embodiment of the present application further provides a non-volatile computer storage medium, which stores computer executable instructions, and the computer executable instructions are configured as follows:

[0049] determining a slewing action of the excavator, controlling a hydraulic pump of the excavator according to the slewing action, so that a hydraulic pump current is executed according to a first slope set in advance;

[0050] determining a preset relief pressure, determining a control current according to the relief pressure;

[0051] determining a preset current target value and a preset acceleration time, determining a second slope according to the control current, the current target value and the acceleration time, and controlling the hydraulic pump so that the hydraulic pump current is executed according to the second slope.

[0052] In the 1990s, it was quite obvious to distinguish whether an improvement in a technology was in hardware (e.g., improvement in circuit structures of diodes, transistors, switches, etc.) or in software (improvement in method flow). However, as technology has evolved, many improvements in method flow today can be considered as direct improvements in hardware circuit structures. Designers almost always obtain the corresponding hardware circuit structures by programming the improved method flow into hardware circuits. Therefore, it cannot be said that an improvement in a method flow cannot be implemented by hardware entity modules. For example, a programmable logic device (PLD) such as a field programmable gate array (FPGA) is an integrated circuit whose logic function is determined by user programming of the device. A digital system is "integrated" on a piece of PLD by the designer programming it by himself, without having to ask a chip manufacturer to design and manufacture a special integrated circuit chip. Moreover, instead of manually fabricating an integrated circuit chip, this programming is now mostly implemented by "logic compiler" software, which is similar to the software compiler used when developing a program, and the original code before compilation also has to be written in a specific programming language, which is called a hardware description language (HDL), and there are many such languages, such as ABEL (Advanced Boolean Expression Language), AHDL (Altera Hardware Description Language), Confluence, CUPL (Cornell University Programming Language), HDCal, JHDL (Java Hardware Description Language), Lava, Lola, MyHDL, PALASM, RHDL (Ruby Hardware Description Language), etc., and the most commonly used are VHDL (Very-High-Speed Integrated Circuit Hardware Description Language) and Verilog. Those skilled in the art should be aware that, as long as the method flow is logically programmed in the above-mentioned hardware description languages and programmed into an integrated circuit, a hardware circuit implementing the logical method flow can be easily obtained.

[0053] The controller can be implemented in any suitable way, for example, the controller can take the form of a microprocessor or processor and a computer readable medium storing computer readable program code, such as software or firmware, executable by the (micro)processor, logic gates, switches, an application specific integrated circuit (ASIC), a programmable logic controller and an embedded microcontroller, examples of which include but are not limited to the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20 and Silicone Labs C8051F320, the memory controller can also be implemented as part of the control logic of the memory. Those skilled in the art will also know that, in addition to implementing the controller in pure computer readable program code, it is also possible to implement the same functionality in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers and embedded microcontrollers by logically programming the method steps. Such a controller can therefore be considered a hardware component, and the means included therein for implementing the various functions can also be considered structures within the hardware component. Alternatively, or even additionally, the means for implementing the various functions can be considered both software modules implementing the method and structures within the hardware component.

[0054] The systems, apparatuses, modules or units illustrated by the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer can be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0055] For the convenience of description, the above apparatuses are described in various units respectively according to their functions. Of course, the functions of the units can be implemented in one or more software and / or hardware in the implementation of the present specification.

[0056] Each of the embodiments in the present application is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. Each embodiment mainly describes the differences from other embodiments. In particular, the device and medium embodiments are basically similar to the method embodiments, and thus the description is relatively simple, and the relevant parts can be referred to the part of the method embodiment.

[0057] The device and medium provided by the embodiments of the present application are one-to-one corresponding, and therefore, the device and medium also have similar beneficial technical effects to the corresponding method. Since the beneficial technical effects of the method have been described in detail above, the beneficial technical effects of the device and medium will not be described here again.

[0058] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. In addition, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage, etc.) containing computer-usable program code.

[0059] The present application is described with reference to flowcharts and / or block diagrams of the method, device (system), and computer program product according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus generate a means for implementing the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 means for carrying out the functions specified in one or more flows and / or blocks.

[0060] These computer program instructions can also be stored in a computer-readable memory that can direct the computer or other programmable data processing apparatus to work in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including instruction means, which implements the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 means for carrying out the functions specified in one or more flows and / or blocks.

[0061] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus, so that a series of operation steps are performed on the computer or other programmable data processing apparatus to produce a computer-implemented process, so that the instructions executed on the computer or other programmable data processing apparatus provide a means for implementing the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 means for carrying out the functions specified in one or more flows and / or blocks.

[0062] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memories.

[0063] Memory can include non-persistent memory and / or volatile memory, such as random access memory (RAM) and / or cache memory, etc. in the form of a computer-readable medium, read only memory (ROM), or flash memory, etc. Memory is an example of computer-readable media.

[0064] Computer-readable media includes permanent and non-permanent, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read only memory (ROM), electrically erasable programmable read only memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), digital versatile disc (DVD), or other optical storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible to a computing device. According to the definition herein, computer-readable media does not include transitory media, such as modulated data signals and carrier waves.

[0065] It should also be noted that the terms "comprising", "containing", or any other variant thereof are intended to cover a non-exclusive inclusion, such that a process, method, article or apparatus that comprises a list of elements does not include only those elements recited, but can also include other elements not expressly listed or inherent to such process, method, article or apparatus. Without further limitation, an element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0066] The above merely provides an example of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the scope of claims of the present application.

Claims

1. A control method of a swing motor of a shovel, characterized by, The method comprises the following steps: determining the slewing action of the excavator, and controlling the hydraulic pump of the excavator according to the slewing action, so that the hydraulic pump current is executed according to a preset first slope; determining a preset relief pressure, and determining the control current according to the relief pressure; determining a preset current target value and a preset acceleration time, determining a second slope according to the control current, the current target value and the acceleration time, and controlling the hydraulic pump so that the hydraulic pump current is executed according to the second slope; determining the control current according to the relief pressure, specifically comprising: determining the relief pressure by the controller of the excavator, and judging the pressure of the hydraulic pump according to the relief pressure; if the pressure of the hydraulic pump is equal to the relief pressure, determining the current value corresponding to the pressure to determine the control current; determining the second slope according to the control current, the current target value and the acceleration time, specifically comprising: the calculation formula of the second slope is: wherein is the second slope, is the current target value, is the control current, is the acceleration time.

2. The method of claim 1, wherein, after the hydraulic pump current is executed according to the second slope, the method further comprises: real-time acquisition of the hydraulic pump current by the controller of the excavator, and judgment of the hydraulic pump current according to the current target value; if the hydraulic pump current is equal to the current target value, the hydraulic pump is controlled to keep the hydraulic pump current.

3. The method of claim 1, wherein, determining the slewing action of the excavator, specifically comprising: determining the handle operation signal of the excavator, and transmitting the handle operation signal to the controller of the excavator; receiving the handle operation signal by the controller, and determining the slewing action of the excavator according to the handle operation signal.

4. The method of claim 3, wherein, Before controlling the hydraulic pump of the excavator according to the slewing action, the method further comprises: starting the hydraulic pump according to the handle operation signal, so that the hydraulic pump current starts to increase from an initial current, wherein the initial current is 0.

5. The method of claim 1, wherein, determining a preset current target value, specifically comprising: determining the motor displacement of the hydraulic pump, and determining the motor output speed corresponding to the slewing action, determining the output flow of the hydraulic pump according to the motor displacement and the motor output speed, and determining the current target value according to the output flow of the hydraulic pump.

6. The method of claim 1, wherein, determining a preset acceleration time, specifically comprising: when the pressure of the hydraulic pump is equal to the relief pressure, determining a first time point corresponding thereto; determining the slewing time according to the slewing action, and determining a second time point according to the slewing time; determining the difference between the second time point and the first time point to determine the acceleration time.

7. A control device for an excavator rotary motor, characterized in that: comprise: at least one processor; and a memory connected in communication with the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the control device of the excavator slewing motor to perform: determining the slewing action of the excavator, and controlling the hydraulic pump of the excavator according to the slewing action, so that the hydraulic pump current is executed according to a preset first slope; Determine a preset relief pressure, determine a control current according to the relief pressure; Determine a preset current target value and a preset acceleration time, determine a second slope according to the control current, the current target value and the acceleration time, and control the hydraulic pump so that the hydraulic pump current is executed according to the second slope; Determine a control current according to the relief pressure, specifically including: Determine the relief pressure through the controller of the excavator, and judge the pressure of the hydraulic pump according to the relief pressure; If the pressure of the hydraulic pump is equal to the relief pressure, determine the current value corresponding to the pressure to determine the control current; Determine a second slope according to the control current, the current target value and the acceleration time, specifically including: The calculation formula of the second slope is: wherein is the second slope, is the current target value, is the control current, is the acceleration time.

8. A non-volatile computer storage medium storing computer-executable instructions, characterized in that: The computer executable instructions are set to: Determine the slewing action of the excavator, control the hydraulic pump of the excavator according to the slewing action, so that the hydraulic pump current is executed according to a preset first slope; Determine a preset relief pressure, determine a control current according to the relief pressure; Determine a preset current target value and a preset acceleration time, determine a second slope according to the control current, the current target value and the acceleration time, and control the hydraulic pump so that the hydraulic pump current is executed according to the second slope; Determine a control current according to the relief pressure, specifically including: Determine the relief pressure through the controller of the excavator, and judge the pressure of the hydraulic pump according to the relief pressure; If the pressure of the hydraulic pump is equal to the relief pressure, determine the current value corresponding to the pressure to determine the control current; Determine a second slope according to the control current, the current target value and the acceleration time, specifically including: The calculation formula of the second slope is: wherein is the second slope, is the current target value, is the control current, is the acceleration time.

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