KR100708957B1 - A fuzzy control method of crawler excavator - Google Patents

Abstract

The present invention relates to a purge control method of an excavator engine and a pump.

The present invention provides an excavator control method using fuzzy modeling by setting an overload table and a load inference value table so as to be suitable for excavator characteristics, wherein the excavator pump pressure value and engine speed value are measured every constant interrupt occurrence. step; Calculating a change amount of the measured pressure value and speed value; A third step of determining the light weight of the load according to the calculation result; And according to the determination result, characterized in that it comprises a fourth step of controlling the engine speed and pump pressure.

The fuzzy control method of the excavator engine and the pump is a discretized linear pump using the overload table and the load inference value table to suit the excavator characteristics and the control characteristics of the excavator engine and the pump using the discharge pressure and discharge rate of the pump. By using the fuzzy modeling by calculating arithmetic from the model, there is an effect that it is possible to control the appropriate output system.

How to control purge of excavator engines / pumps

Description

A fuzzy control method of crawler excavator}

1 is a main configuration of a hydraulic excavator according to the present invention,

2 is a characteristic curve of an engine and a pump according to the present invention,

3 is a configuration diagram of a digital controller of a pump engine system according to the present invention;

4 is a P-Q characteristic curve according to the present invention,

5 is a derived load inference value table according to the present invention;

6 is a control flowchart of the entire system according to the present invention;

7 is a flowchart for controlling excavator engine speed and pump pressure according to the present invention;

8 is a flowchart for measuring an excavator pump input value and an engine speed value according to the present invention;

9 is a flow chart for calculating the amount of change in the measured pressure value and speed value according to the present invention;

10 is a flow chart for controlling engine speed and pump pressure in accordance with the present invention.

* Description of the main symbols in the drawings

10: pump controller 20: engine controller                 

30: pump 40: engine

The present invention relates to a fuzzy control method for an excavator engine and a pump, and more particularly, to fuzzy modeling by arithmetically calculating control characteristics of an excavator engine and a pump from discrete linear pump models using the discharge pressure and the discharge pressure change rate of the pump. The present invention relates to a fuzzy control method of an excavator engine and a pump which enables more efficient engine and pump control by improving output characteristics according to nonlinear characteristics.

In general, the control technology of a variable displacement pump used in a conventional excavator is mainly composed of a linear controller such as a proportional controller or a proportional-integral-differential (PID). Such a control system is difficult to model. Therefore, it was difficult to expect the same control characteristics. In addition, since the engine-pump system has nonlinearity and the engine speed is slower than the loaded load, it is difficult to properly control by simple PID control. There was also a disadvantage that the countermeasures against unnecessary engine power waste and overload were insufficient.

Accordingly, the present invention has been made to solve the above problems, by using a fuzzy modeling by calculating the arithmetic characteristics of the excavator engine and the pump control by arithmetic calculation from the discretized linear pump model using the discharge pressure and discharge pressure change rate of the pump The purpose of the present invention is to provide a fuzzy control method for an excavator engine and a pump that enables more efficient engine and pump control by improving output characteristics according to nonlinear characteristics.

In order to achieve the above object, the fuzzy control method of the excavator engine and the pump according to the present invention in the excavator control method using fuzzy modeling by setting an overload table and load inference value table to suit the characteristics of the excavator A first step of measuring an excavator pump pressure value and an engine speed value at each constant interrupt occurrence; Calculating a change amount of the measured pressure value and speed value; A third step of determining the light weight of the load according to the calculation result; And according to the determination result, characterized in that it comprises a fourth step of controlling the engine speed and pump pressure.

The first step includes the steps of measuring the analog pressure value of the pump every time a certain interrupt occurs; Converting the measured analog pressure value into a digital pressure value; Measuring a pulse signal of the engine every time a certain interrupt occurs; And converting the measured pulse signal into a digital speed value, wherein the second step includes: obtaining an effective pressure value by multiplying a gain value defined by the digital pressure value; Obtaining the pressure change amount by subtracting the effective pressure value from the previously measured effective pressure value; Adjusting the effective pressure value and the pressure change amount within a normal range; Obtaining a setpoint value set in an overload table corresponding to the adjusted effective pressure value and pressure change amount; And subtracting the measured speed value from the previously measured speed value to obtain a speed change amount.

The fourth step may include: performing proportional-integral-derivative (PID) control with respect to engine speed according to the determination result; And in accordance with the performance, giving a speed command to the engine controller and giving a command to the proportional valve to control the engine speed and the pump pressure.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

1 is a main configuration diagram of a hydraulic excavator according to the present invention, which can be divided into a cylinder block including an engine, a pump, and a control valve, and the discharge flow rate of the pump is determined in proportion to the input current of the electromagnetic proportional valve attached to the pump. do. The discharged pressure oil is delivered to various cylinders and motors through hydraulic hoses. The total flow rate to be supplied to each actuator of the excavator is determined and adjusted by the pump-engine controller.

Figure 2 shows the characteristic curve of the engine and the pump according to the present invention, the upper figure shows the torque and output, and the fuel consumption rate for the engine speed, the lower figure shows the horsepower line of the pump and the horsepower line of the engine PQ diagram Represented by The non-linear bending of the pump's horsepower line in the figure is because the pump consists of two, which makes it difficult to produce a proper output by general PID control that can be controlled linearly. Therefore, fuzzy modeling is used to allow control along the horsepower curve of nonlinear pumps. First, it is difficult to implement the above control algorithm in the analog type of the previous excavator, and the algorithm can be applied where the digital controller is designed.

3 is a schematic diagram of a digital controller of a pump-engine system according to the present invention, which controls a pump controller 10 and a throttle motor of an engine for controlling a pump and various solenoids and performing other functions. It consists of the engine controller 20 for doing so. The pump controller 10 includes an MCU unit 11 for operation, a solenoid driver unit 12 for opening and closing various hydraulic circuits, a PWM driver unit 13 for driving P / V, and a memory unit for storing information ( 14), A / D unit 15 for measuring pressure and the like, and W / S (Wave Shaping) unit 16 for measuring RPM and the like are largely configured. Then, the solenoid is opened and closed in accordance with the working conditions, the discharge pressure of the two pumps is input from the pump, the speed of the load is determined in consideration of the change ratio, and the engine controller 20 is given a speed command, and the proportional pressure reducing valve of the pump ( Give a command to 31). The engine controller 20 includes an MCU unit 21 for operation, an A / D unit 22 for receiving a command of a pump controller, a memory unit 23 for storing information, and a W / S for measuring RPM. Shaping) section 24, PWM driver section 25 for driving the throttle motor, etc. are large, and controls the throttle motor 41 in accordance with the command of the pump controller (10).

4 is a P-Q characteristic curve according to the present invention, based on the following system characteristics. If the pressure rises below the pressure at which pressure compensation begins on the P-Q diagram, no overload occurs. In the pressure section above the pressure at which pressure compensation starts from the slope of the P-Q diagram, the relative low pressure section causes a large change in load torque for the same pressure fluctuation compared to the high pressure section. Under the above conditions, the controller uses the fuzzy model of the load to determine the light weight of the load in real time, and when the engine can not handle the load with the set engine output during operation or the output remains compared to the load, the engine output is adjusted by adjusting the engine speed. To set up or down.

5 is a derived load inference value table according to the present invention. The difference between the output torque of the engine and the absorption torque of the pump is called an overload. In the present invention, fuzzy modeling is established by inferring the degree of load from the pump pressure and the rate of change of the pump pressure. For example, if the overload index is positive, the power is underpowered. If the overload index is negative, the power is overpowered. The pressure P ranges from 0 to 350 bar, divided by the concept of HI and LO, because the pressure naturally occurs when the engine is started, and the pressure cannot be negative or zero. Therefore, the pressure can be expressed as high and low, which is divided into four simple steps. The pressure change (dP) was divided into five stages in consideration of the case where there are many changes in the engine, starting from a low rpm and going to a high rpm, and when there is a large change in the change. Changes in each step move to the next level below -15 bar and up to +15 bar. So, if it is not changed to below or above, the current state is maintained. Pressures are LO, ML per rpm. The criteria for MH and HI change, which is related to the engine performance curve. The fuzzy control output is determined by the fuzzy controller and the fuzzy controller is approximated by the following control rules and language variables.                     

If pressure (P) = LO and pressure variation (dP) = PB then purge control output = PS

If pressure (P) = LO and pressure variation (dP) = PS then purge control output = PS

             ::

If pressure (P) = HI and pressure change (dP) = NB then purge control output = NS

For this rule, for example, if the pressure is LO and the pressure change is extreme, the load is high. However, since the pressure is the lowest, it may take a lot even at a small load, so set the load factor to PS. If the pressure is HI and the pressure change is PB, the load will be high, but the control range is in a very high position. In this way, the pressure and pressure change can be set accordingly. In addition, if the overload is continuously PB, the engine speed should be increased rather than pressure control, so the engine is adjusted to increase the rpm.

The control method according to the overload can be a combination of a method of changing the rated speed continuously and discontinuously in all areas. The method of continuously changing the rated speed in all areas is 40s% UP when the overload is PB, 20% when the overload is PS, and 20% when the overload is NS. DOWN), and if the overload is NB, reduce the rated speed by 40%. The method of discontinuously changing the rated speed based on the speeds for the 1st, 2nd, and 3rd speeds purges the upper and lower areas around the rated speed in each power mode. Raise (1 → 2, 2 → 3 speeds), and if the overload is net NB, decrease the rated speed (3 → 2, 2 → 1 speeds).

FIG. 6 is a control flowchart of the entire system according to the present invention, in which an initialization unit sets an interrupt initiation for generating an interrupt at a predetermined time interval and a load inference value table for fuzzy control, and from the outside of the controller at the time of initialization. There is a communication unit 93, various control algorithms 94, and an output unit 95 between an I / O input processing unit 92 for processing an input and a display device for indicating a current state. These routines poll continuously, executing the interrupt service when an interrupt occurs. The inference value is divided into 20 steps from -10 to +10. If it is 0, it is the government load, -10 is the overpower state, and +10 is the overload state. Make necessary values available every time status is determined.

FIG. 7 is a flowchart for controlling an excavator engine speed and a pump pressure according to the present invention. First, an excavator pump input value and an engine speed value are measured at each constant interrupt occurrence (110), and a change amount of the measured input value and the speed value is calculated. Calculate (120). Then, according to the calculation result, the controller determines the weight of the load in real time using fuzzy modeling of the load (130), and controls the engine speed and the pump pressure according to the determination result (140).

8 is a flowchart for measuring an excavator pump input value and an engine speed value according to the present invention. First, the pump pressure value is measured every time a predetermined interrupt occurs (111), and the measured pressure value is converted into a digital value through an analog-to-digital converter. Transform (112). Whenever a certain interrupt occurs, the engine rotates the pulse signal (113) and converts it into a digital speed value (114).

FIG. 9 is a flowchart for calculating a change amount of the measured pressure value and the speed value according to the present invention. First, the effective pressure value is obtained by multiplying the digital pressure value by an appropriate gain value according to the offset for each sensor to be measured (121). In step 122, the pressure change amount is obtained by subtracting the current valid pressure value from the previous valid pressure value. Then, if the pressure value is more than 350 bar, it is limited to 350 because it is a wrong input exceeding the reference range. If the pressure change is more than ± 100 per sample time, it is limited to ± 100 and adjusted within the normal range (123). In operation 124, a command value is obtained by a combination of the pressure P and the pressure change amount dP in the overload table preset for the characteristics of the excavator. As an example of setting up a table, the horizontal axis of the table can be divided into 31, including 0 for the change of ± 15 bar, and 36, including 0 for the 350 bar divided by 10. The speed change amount dV is obtained by subtracting the current speed value from the previous speed value (125).

Figure 10 is a flow chart for controlling the engine speed and the pump pressure according to the present invention, if the pressure change is high, so the engine rpm should be increased to perform PID control for the engine speed (141), and as a result the speed to the engine controller Commands are given to the command and proportional valve to control engine speed and pump pressure (142).

As described above, the fuzzy control method for an excavator engine and a pump includes setting an overload table and a load inference value table to suit the characteristics of the excavator, and using the discharge pressure and discharge rate of the pump to control the characteristics of the excavator engine and the pump. Arithmetic calculations from discrete linear pump models and fuzzy modeling have the effect of enabling proper output system control.

Claims (4)

A fuzzy control method for an excavator engine and a pump using fuzzy modeling in which an overload table and a load inference value table are set to be suitable for excavator characteristics, Measuring an excavator pump pressure value and an engine speed value at each constant interrupt occurrence; Calculating a change amount of the measured pump pressure value and engine speed value; Determining the light weight of the load based on the calculated change amount of the pump pressure value and the engine speed value; And And controlling the engine speed and the pump pressure according to the light weight of the determined load. The method of claim 1, wherein the measuring of the pump pressure value and the engine speed value comprises: Measuring the analog pressure value of the pump every time a certain interrupt occurs; Converting the measured analog pressure value into a digital pressure value; Measuring a pulse signal according to the speed of the engine each time a predetermined interrupt occurs; And And a method of converting the measured pulse signal into a current digital speed value. The method of claim 2, wherein the calculating of the change amount of the pump pressure value and the engine speed value comprises: Calculating a current effective pressure value by multiplying the digital pressure value by a predefined gain value; Obtaining a pressure change amount by subtracting the calculated current effective pressure value from a previously measured effective pressure value; Adjusting the current effective pressure value and the pressure change amount within a normal range; Obtaining a command value corresponding to the adjusted current effective pressure value and pressure change amount in an overload table previously stored; And And calculating the speed change amount by subtracting the measured current digital speed value from the previously measured digital speed value. 2. The method of claim 1, wherein controlling the engine speed and pump pressure comprises: Performing proportional-integral-derivation (PID) control for engine speed according to the determined weight of the load; And And controlling the engine speed and the pump pressure by giving a speed command to an engine controller and giving a command to the proportional valve according to the performance of the proportional-integral-derivative control.

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