JPH08177087A - Controller of construction machinery - Google Patents

Abstract

PURPOSE: To improve the response of a controller for construction machines. CONSTITUTION: When starting to drive a load 4, a pilot pressure signal of a changeover valve 5, a delivery pressure signal of a hydraulic pump 1a and a slant angle signal of the hydraulic pump are input in a controller 2. The controller 2 operates an aimed value of the slant angle of the hydraulic pump 1a on the basis of a smaller pressure signal in the pilot pressure signal and the delivery pressure signal. The aimed value is input in an aimed value limiter and set so that the upper limit thereof is smaller than the maximum slant angle of the hydraulic pump 1a and also the lower limit thereof is larger than the minimum slant ange. Next, the deviation between the aimed value and the measured value of the slant angle is operated and an instruction value showing a new slant angle is operated on the basis of the integral value of deviation. The instruction is transmitted to the hydraulic pump 1a through a regulator 1b to alter the slant angle thereof. In this way, the instruction value can be overshot.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a construction machine, which controls a control target based on a deviation between an actual measurement value and a target value of a control value indicating a control magnitude of the control target.

[0002]

2. Description of the Related Art As a construction machine equipped with a control device of this type, there is a wheel type hydraulic excavator as shown in FIG. 5, for example. In FIG. 5, reference numeral 51 is a hydraulic motor, and the rotation of the hydraulic motor 51 drives the rear wheels 54 via the transmission 52 and the propeller shaft 53 to drive the vehicle. The boom cylinder 55 is expanded and contracted by the rotation of the hydraulic motor 51, and the boom 56, which is a part of the front attachment, is moved up and down.

FIG. 6 is a control block diagram for controlling a tilting angle of a variable displacement hydraulic pump (hereinafter simply referred to as a hydraulic pump) (not shown) for driving the hydraulic motor 51 of FIG.
In FIG. 6, reference numeral 101 denotes a target value calculation circuit that calculates a target value of the tilt angle of the hydraulic pump that is the controlled object 1 based on a predetermined formula. The target value calculation circuit 101 includes an operation lever (not shown). A signal corresponding to the operation amount is input. 10
Reference numeral 2 is a target value limiter that corrects the target value so that the target value calculated by the target value calculation circuit 101 falls within a range of predetermined upper limit value and lower limit value.

As shown in FIG. 7, a target value limiter 102
Is a target value set within this range, with an upper limit value being a value larger than the maximum tilt angle of the hydraulic pump by an upper limit value, and a lower limit value being a value smaller by a predetermined angle than the minimum tilt angle of the hydraulic pump.
That is, the target value limiter 102 reliably changes the tilt angle to the maximum tilt angle or the minimum tilt angle even if the maximum tilt angle and the minimum tilt angle of the hydraulic pump change due to manufacturing error, assembly error, or the like. As much as possible, the target value setting range is a range with a little margin from the range determined by the maximum tilt angle and the minimum tilt angle. By providing the target value limiter 102, the target value does not largely deviate from the range determined by the maximum tilt angle and the minimum tilt angle, and the deviation between the target value and the actually measured value becomes small.

In FIG. 6, 103 is a tilt angle detector for measuring the tilt angle of the hydraulic pump, and 104 is a tilt angle detector 1.
The difference unit calculates the deviation between the actual value of the tilt angle detected by 03 and the target value output from the target value limiter 102. Reference numeral 105 denotes a steady-state deviation compensator that integrates the deviation calculated by the differencer 104, and 106 outputs a command value for changing the tilt angle of the hydraulic pump based on the integrated value output from the steady-state deviation compensator 105. It is a stabilization compensator (for example, a PID compensator).

Reference numeral 107 is a command value limiter which corrects the command value so that the command value falls within a range of predetermined upper limit value and lower limit value. As shown in FIG. 8, the command value limiter 10
7, the upper limit value is a value larger than the actual measurement value corresponding to the maximum tilt angle by the upper limit value, and the lower limit value is the predetermined value smaller than the actual measurement value corresponding to the minimum tilt angle, and the command value is set within this range.

The reason for providing the command value limiter 107 is mainly for the following reason. Even if the tilt angle of the hydraulic pump reaches the maximum tilt angle, an angle smaller than the maximum tilt angle may be measured due to an error in the mounting position of the tilt angle detector 103 or the like. Further, since the target value limiter 102 sets the upper limit value to a value that is larger than the maximum tilt angle by a predetermined angle, as shown in FIG. 9, the measured tilt angle value (two-dot chain line in the figure).
A certain deviation may occur between the target value and the target value (solid line in the figure). Since this deviation continues to increase due to the integration action of the steady deviation compensator 105, the stabilization compensator 106 outputs a command value that rises to the right as shown by the one-dot chain line in an attempt to eliminate this deviation.

If the target value suddenly decreases in this state, the command value also decreases accordingly, but the tilt angle actually begins to change after the time when the command value and the measured value become substantially equal. Therefore, as shown by the arrow range in the drawing, a response delay occurs for a predetermined time from the change of the target value to the actual change of the tilt angle. On the other hand, the command value limiter 10
If 7, the command value does not reach a certain level or more even if there is a certain deviation between the target tilt angle and the actual tilt angle, as shown in FIG. The delay is shorter than in FIG.

[0009]

In order to improve the responsiveness of the hydraulic pump, it is necessary to overshoot or undershoot the command value. For example, in order to increase the tilt angle in a short time when the tilt angle of the hydraulic pump is sufficiently small, it is desirable to overshoot the command value as shown by the dotted line in FIG. This allows
The tilt angle can be increased in a short time.

However, as shown in FIG. 6, the command value limiter 1
When 07 is provided, the upper limit value of the command value is limited as shown by the chain double-dashed line in FIG. 11, so the command value cannot be overshooted and the responsiveness deteriorates. . Further, if an attempt is made to respond by force, the command value will vibrate and the stability will deteriorate.

An object of the present invention is to provide a control device for a construction machine capable of improving responsiveness when controlling an object to be controlled without impairing its stability.

[0012]

The present invention will be described with reference to FIGS. 1 and 2 showing an embodiment.
Target value calculating circuit 101A for calculating a target value indicating the control magnitude of the target value, and a target value limit for limiting the size of the target value so that the calculated target value falls within a range of predetermined upper limit value and lower limit value. A circuit 102A, a control value measuring means 9 for measuring a control value indicating an actual control magnitude of the controlled object 1, and a deviation calculation circuit 104A for calculating a deviation between a limited target value and the measured control value. , An integrating circuit 105A for integrating the calculated deviation, and a command value calculating circuit 10 for calculating a command value for changing the control value based on the integrated deviation.
6A is applied to a control device for a construction machine, and the target value is set so that the upper limit value of the target value is smaller than the upper limit value of the control value and the lower limit value of the target value is larger than the lower limit value of the control value. The above object is achieved by configuring the limiting circuit 102A. The invention according to claim 2 is a target value calculation circuit 101A for calculating a target value of the pump displacement angle of the variable displacement hydraulic pump 1a, and the calculated target value is within a range of predetermined upper and lower limit values. As described above, the target value limiting circuit 102A for limiting the magnitude of the target value, the limit value measuring means for measuring the pump displacement angle, and the deviation for calculating the deviation between the limited target value and the measured pump displacement angle Arithmetic circuit 10
4A and an integrating circuit 105A for integrating the calculated deviation
And a command value calculation circuit 106A that calculates a command value for changing the pump tilt angle based on the integrated deviation, and is applied to a control device for a construction machine. The target value limiting circuit 1 is designed so that it is smaller than the maximum tilt angle of the pump 1a, and the lower limit value of the target value is larger than the minimum tilt angle of the variable displacement hydraulic pump 1a.
By configuring 02A, the above object is achieved.
According to a third aspect of the present invention, in the construction machine control device according to the second aspect, the hydraulic actuator 3 driven by the discharge oil from the variable displacement hydraulic pump 1a, the variable displacement hydraulic pump 1a and the hydraulic actuator 3 are used. And a control valve 5 that is provided between the control valve 5 and the control valve 5 that controls the supply of the discharge oil to the hydraulic actuator 3 by the pilot pressure according to the operation amount of the operation lever 7, and the discharge pressure measurement that measures the discharge pressure of the variable displacement hydraulic pump 1a The target value calculating circuit 101A is provided with the means 10 so that the smaller one of the target tilt angle obtained based on the pilot pressure and the target tilt angle obtained based on the discharge pressure is used as the target value. It is what constitutes.

[0013]

According to the first aspect of the invention, the target value indicating the magnitude of control of the controlled object is calculated by the target value calculation circuit. The calculated target value is input to the target value limiting circuit 101A,
The size of the target value is limited so that it falls within the range of the predetermined upper limit value and lower limit value. On the other hand, the control value measuring means 9 measures a control value indicating the magnitude of the actual control of the controlled object. Both the target value limited by the target value limiting circuit 101A and the control value measured by the control value measuring means 9 are input to the deviation calculating circuit 104A, and the deviation between the target value and the control value is calculated. This deviation is integrated by the integration circuit 105A, and the command value calculation circuit 106A calculates a command value based on the integrated value to minimize the deviation, and changes the control value based on the calculated command value. In the above calculation, by setting the upper limit value of the target value calculated by the target value calculation circuit 101A to be smaller than the upper limit value of the control value and making the lower limit value of the target value larger than the lower limit value of the control value, The command value calculated by the value calculation circuit 106A can be overshot or undershooted. In the second aspect of the invention, the target value of the pump displacement angle of the variable displacement hydraulic pump is calculated by the target value calculation circuit. The calculated target value is input to the target value calculation circuit, and the size of the target value is limited so that it falls within a range of predetermined upper limit value and lower limit value. On the other hand, the control value measuring means measures the pump tilt angle. The target value limited by the target value limiting circuit and the control value measured by the control value measuring means are both input to the deviation calculating circuit, and the deviation between the target value and the control value is calculated.
This deviation is integrated by the integration circuit, and the command value calculation circuit calculates the command value for changing the control value based on the integrated value. In the above calculation, the upper limit value of the target value of the pump tilt angle calculated by the target value calculation circuit 101A should be smaller than the maximum tilt angle, and the lower limit value of the target value should be larger than the minimum tilt angle. Command value calculation circuit 1
The command value calculated by 06A can be made to overshoot or undershoot. In the invention according to claim 3, the hydraulic actuator 3
Switching means 5 for switching whether or not the discharge oil is supplied to
The target value is calculated based on the smaller one of the pilot pressure of 1 and the discharge pressure of the variable displacement hydraulic pump 1a to reduce the deviation between the target value and the actually measured value.

Incidentally, in the section of means and action for solving the above-mentioned problems for explaining the constitution of the present invention, the drawings of the embodiments are used for the sake of easy understanding of the present invention. It is not limited to.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a diagram showing an embodiment in which a control device for a construction machine according to the present invention is applied to pump tilt angle control of a hydraulic excavator. In FIG. 1, reference numeral 1 denotes a control target that is drive-controlled by a controller 2, and is a hydraulic pump 1a.
And a regulator 1b for controlling the tilt angle of the hydraulic pump 1a. Reference numeral 3 is a hydraulic motor that drives the load 4 by the oil discharged from the hydraulic pump 1a. Reference numeral 5 denotes a switching valve that switches between supplying the oil discharged from the hydraulic pump 1a to the hydraulic motor 3 and returning the oil to the tank 6.

Reference numeral 7 is an operating lever for controlling the switching direction of the switching valve 5, and the pilot pressure of the pilot port 5a of the switching valve 5 changes depending on the operation amount of the operating lever 7, whereby the switching direction of the switching valve 5 is changed. Change. Specifically, when the load 4 is not driven, the load 4 is shown at the position "b" shown in the figure, and when the load 4 is driven in the direction A shown, the load 4 is shown at the position "a" shown in the figure. In the case of driving in the B direction, the positions are switched to the positions shown in "C". 8 is a pilot port 5a of the switching valve 5
A pilot pressure detector for detecting the pilot pressure of the hydraulic pump 1; a tilt angle detector 9 for detecting the tilt angle of the hydraulic pump 1a;
Is a pump discharge pressure detector for detecting the discharge pressure of the hydraulic pump 1a.

FIG. 2 is a block diagram showing the internal structure of the controller 2, and the same components as those in FIG. 6 described above are designated by the same reference numerals. In FIG. 2, 101A is a target value calculation circuit for calculating the target value of the tilt angle of the hydraulic pump 1a, and the pilot pressure signal detected by the pilot pressure detector 8 and the discharge detected by the pump discharge pressure detector 10 are indicated. The pressure signal and are input. The target value calculation circuit 101A detects the target tilt angle based on the smaller one of the tilt angle calculated based on the pilot pressure signal and the tilt angle calculated based on the discharge pressure signal.

Reference numeral 102A is a target value limiter for converting the target value of the tilt angle into a voltage value and for limiting the voltage so that the voltage value falls within a predetermined upper and lower limit range. As shown in FIG. 3, the target value limiter of this embodiment has a voltage value V corresponding to the maximum tilt angle of the hydraulic pump 1a.
A value smaller than max by a predetermined value Vall is set as an upper limit value, and a value larger than the voltage value Vmin corresponding to the minimum tilt angle of the hydraulic pump 1a by a predetermined value Vall is set as a lower limit value, and the target value is limited within this range. The predetermined value Vall is the hydraulic pump 1
It is set in consideration of the manufacturing error and the assembly error of a.

Returning to FIG. 2, 104A is a difference device for calculating the deviation between the output of the target value limiter 102A and the actual value of the tilt angle detected by the tilt angle detector 9, and 105A is an output from the difference device 104A. The steady deviation compensator 106A that integrates the generated deviation is a stabilization compensator 106A that outputs a command value for changing the tilt angle of the hydraulic pump 1a based on the integrated value output from the steady deviation compensator 105A. . The command value output from the stabilization compensator 106A is the regulator 1
It is input to b and converted into a signal for driving the hydraulic pump 1a.

Next, the operation of the construction machine controller configured as described above will be described. When the load 4 is not driven, the switching valve 5 is set to the “b” position in FIG. 1, and the pipeline connecting the hydraulic pump 1a and the hydraulic motor 3 is cut off. In this state, the operator operates the operation lever 7
When is operated, a pilot pressure is applied to the pilot port 5a of the switching valve 5, and the switching valve 5 is switched to the “A” position or the “C” position. Thereby, the hydraulic pump 1
The oil discharged from a flows to the hydraulic motor 3 via the switching valve 5, and the drive of the load 4 is started.

At this time, the controller 2 sends a signal indicating the pilot pressure of the pilot port 5a (pilot pressure signal).
And a signal indicating the discharge pressure of the hydraulic pump 1a (discharge pressure signal)
And a signal indicating the tilt angle of the hydraulic pump 1a (tilt angle signal). The controller 2 outputs the smaller angle value of the tilt angle obtained by the pilot pressure signal and the tilt angle obtained by the discharge pressure signal as the target value of the tilt angle of the hydraulic pump 1a. This target value is input to the target value limiter 102A, the upper limit value and the lower limit value are limited, and then the deviation between the target value and the measured value of the tilt angle is calculated, and a new value is integrated based on the integrated value of this deviation. A command value indicating the tilt angle is calculated. This command value is sent to the hydraulic pump 1a via the regulator 1b, and the tilt angle is changed.

In such an operation, the target value limiter 102A of this embodiment makes the upper limit of the target value smaller than the maximum tilt angle of the hydraulic pump 1a, and the lower limit value of the target value below the minimum tilt angle. Since the value is set large, the tilt angle can be actually changed to the upper limit or the lower limit of the target value, and the deviation between the target value and the tilt angle does not occur. Therefore, it is possible to overshoot or undershoot the command value without providing a command value limiter as in the conventional case.

FIG. 4 shows a command value, a target value, a measured value of the tilt angle when control is performed in this embodiment (hereinafter referred to as a measured value during control), and a case where control is not performed in this embodiment. FIG. 6 is a diagram showing how measured values of tilt angles (hereinafter, referred to as measured values during no control) change with time. FIG. 4 shows a state in which the target value is changed stepwise. The command value is indicated by a one-dot chain line, the target value is indicated by a solid line, the actual measurement value during control is indicated by a two-dot chain line, and the actual measurement value during no control is indicated. It is indicated by a broken line.

Since the present embodiment does not limit the command value,
When the deviation between the target value and the measured value is large, as at time t1 in FIG. 4, the command value can be overshot, and the measured value can be brought closer to the target value more quickly. Therefore, the responsiveness is improved as compared with the conventional case. Also,
Since it is not necessary to provide the command value limiter 107 shown in FIG. 6, the internal structure of the controller 2 is simplified.

In the above embodiment, the case where the present invention is applied to the tilt angle control device for a variable displacement hydraulic pump has been described. However, the controlled object of the present invention is not limited to this, and for example, the tilt displacement of a variable displacement hydraulic pump is used. It is widely applicable to angular velocity control, discharge flow rate and discharge pressure control of various pumps, engine speed control, motor / cylinder position / speed control, and work arm position / speed control. As the stabilization compensator of the above embodiment, for example, a PID compensator based on the classical control theory or a state feedback compensator based on the modern control theory may be used. Each component inside the controller shown in the figure may be configured by hardware or software.

In the embodiment constructed as described above, the target value limiter 102A serves as the target value limiting circuit, the tilt angle detector 9 serves as the control value measuring means, the differentiator 104A serves as the deviation calculating circuit, and the steady-state deviation is provided. The compensator 105A serves as an integration circuit, the stabilization compensator 106A serves as a command value calculation circuit, the hydraulic motor 3 serves as a hydraulic actuator, the switching valve 5 serves as a switching means, and the pump discharge pressure detector 10 serves as a discharge pressure measuring means. Correspond.

[0027]

As described in detail above, according to the present invention, the upper limit value of the target value is made smaller than the upper limit value of the control value, and the lower limit value of the target value is made larger than the lower limit value of the control value. Therefore, even if the target value is maximized or minimized, the deviation between the measured value and the target value does not occur. Therefore, the command value limiter provided in the conventional device is not required, so that the command value for changing the control value can be overshooted or undershot, and the responsiveness at the time of controlling the controlled object can be improved. And the stability is improved. According to the invention described in claim 2, the upper limit value of the target value of the tilt angle of the variable displacement hydraulic pump is made smaller than the maximum tilt angle,
To make the lower limit of the target value larger than the minimum tilt angle,
The command value for changing the tilt angle can be overshot or undershooted, and the responsiveness and stability when changing the tilt angle are improved. According to the invention of claim 3, the target value is calculated based on the smaller one of the pilot pressure for switching the switching means and the discharge pressure of the hydraulic pump.
The deviation between the measured value and the target value of the tilt angle can be reduced.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a control device that controls a pump tilt angle of a hydraulic excavator.

FIG. 2 is a block diagram showing the internal configuration of the controller shown in FIG.

FIG. 3 is a diagram showing characteristics of a target value limiter of the present embodiment.

FIG. 4 is a diagram showing a temporal change of a command value, a target value, an actual measurement value during control and an actual measurement value during no control in the present embodiment.

FIG. 5 is a view showing the outer appearance of a wheel hydraulic excavator.

FIG. 6 is a block diagram of a control device for a conventional construction machine.

FIG. 7 is a diagram showing characteristics of a conventional target value limiter.

FIG. 8 is a diagram showing characteristics of a conventional stabilization compensator.

FIG. 9 is a diagram showing a response delay when a command value limiter is not provided.

FIG. 10 is a diagram showing a response delay when a command value limiter is provided.

FIG. 11 is a diagram showing a temporal change of a conventional command value, a target value, a measured value during control, and a measured value during no control.

[Explanation of symbols]

 1 Control target 2 Controller 3 Hydraulic motor 4 Load 5 Switching valve 6 Tank 7 Operating lever 8 Pilot pressure detector 9 Tilt angle detector 10 Discharge pressure detector 101, 101A Target value calculation circuit 102, 102A Target value limiter 104, 104A Difference device 105,105A Steady-state compensator 106,106A Stabilization compensator

Claims (3)

[Claims] 1. A target value calculation circuit for calculating a target value indicating the magnitude of control of a controlled object, and a target value calculation circuit for calculating the target value so that the calculated target value falls within a range of predetermined upper and lower limits. A target value limiting circuit for limiting the magnitude, a control value measuring means for measuring a control value indicating the magnitude of the actual control of the controlled object, and a deviation between the limited target value and the measured control value A deviation calculation circuit that calculates a deviation, an integration circuit that integrates the calculated deviation, and a command value calculation circuit that calculates a command value for changing the control value based on the integrated deviation, The target value limiting circuit is configured such that the upper limit value of the target value is smaller than the upper limit value of the control value, and the lower limit value of the target value is larger than the lower limit value of the control value. Control device. 2. A target value calculation circuit for calculating a target value of a pump displacement angle of a variable displacement hydraulic pump, and the target value so that the calculated target value falls within a range of predetermined upper and lower limits. A target value limiting circuit that limits the magnitude of the pump displacement, a limit value measuring unit that measures the pump displacement angle, and a deviation calculation circuit that calculates the deviation between the limited target value and the measured pump displacement angle. A target value limiting circuit for calculating a command value for changing the pump tilt angle based on the integrated deviation, and an integration circuit for integrating the calculated deviation. Is characterized in that the upper limit of the target value is smaller than the maximum tilt angle of the variable displacement hydraulic pump, and the lower limit of the target value is larger than the minimum tilt angle of the variable displacement hydraulic pump. Construction machine Mechanical control device. 3. The control device for a construction machine according to claim 2, wherein the hydraulic actuator driven by the oil discharged from the variable displacement hydraulic pump and the variable actuator provided between the variable displacement hydraulic pump and the hydraulic actuator. A control valve for controlling the supply of the discharge oil to the hydraulic actuator by a pilot pressure according to the operation amount of the operation lever, and a discharge pressure measuring means for measuring the discharge pressure of the variable displacement hydraulic pump, The target value calculation circuit sets the smaller one of the target tilt angle obtained based on the pilot pressure and the target tilt angle obtained based on the discharge pressure as the target value. Control equipment for construction machinery.