JPH06159304A - Control device for hydraulic actuator - Google Patents

Abstract

PURPOSE:To carry out positioning and speed control with high accuracy by stopping an actuator after maintaining the actuator at low speed for a prescribed time just before stopping the actuator, and correcting a next low speed maintaining time by the difference between the stopping position thereof and a set target position. CONSTITUTION:In a control unit 4, the set data of a driving pattern and the like is taken from a setter 5, and a position signal is received from a position detector 2. When an actuator reaches a deceleration start position on the basis of a set data, a speed command is created so as to decelerate the actuator in compliance with a prescribed deceleration pattern, and a flow rate command signal is outputted to a proportional flow rate control valve 3 on the basis thereof. The actuator 1 is thus decelerated, and stopped after lapse of a prescribed time. And then the actuator 1 is stopped, a real stopping position signal is taken-in from a position detector 2, and a deviation between the stopping position and a set target position is found out, and then a deceleration maintain time in the driving pattern is corrected. Next deceleration is controlled by the corrected maintaining time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an open loop controller for a hydraulic actuator.

[0002]

2. Description of the Related Art Conventionally, as a device for accurately positioning a hydraulic actuator, a closed loop control device using a servo valve and a proportional flow control valve provided with a fixed position detector such as a limit switch at a predetermined position. A device for driving an open loop is known.

[0003]

However, although the former device described above can perform highly accurate positioning control, it has a problem that the device becomes complicated and manufacturing and maintenance costs increase. On the other hand, the latter device has a simple problem. Although the cost can be reduced by such a configuration, there is a problem in high-precision positioning control because the positioning accuracy is limited.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an open loop controller for a hydraulic actuator, which positions and speeds the hydraulic actuator with high accuracy.

[0005]

In the present invention, in FIG. 1, a hydraulic actuator 1 to which hydraulic pressure is supplied from a control valve 30, a means 20 for detecting a displacement amount of the hydraulic actuator 1, and a preset operation are provided. Means 2 for delivering a first speed command signal as a function of time based on the accelerated pattern
1, means 22 for determining a deceleration position from the detected displacement amount, and means 23 for transmitting a second speed command signal corresponding to a deceleration pattern preset based on the result of the determination as a function of time. A means 31 for driving the control valve 30 based on the speed command signal, and a means 24 for judging that the second speed command signal has been decelerated to a predetermined low speed.
A means 25 for holding the low speed for a preset time based on the result of this determination, a means 28 for setting the speed command signal to zero based on the passage of the holding time, and a stop based on the detected value of the displacement amount. A position detecting unit 26 and a unit 27 for correcting the predetermined holding time from the detected stop position and a preset stop target position are provided.

Further, the control valve is composed of a flow rate control valve having a flow rate estimating means.

[0007]

Therefore, immediately before the hydraulic actuator is stopped, a predetermined low speed is maintained for a predetermined time and then stopped, and the time for maintaining the predetermined low speed is determined by the difference between the actual stop position and the preset stop target position. Since the next drive of the hydraulic actuator is performed based on the corrected low speed holding time, it is possible to perform high-precision positioning by reducing the effect of temperature or load variation of the hydraulic actuator. Become.

Further, since the control valve is a flow rate control valve having a flow rate estimating means, it is possible to suppress the fluctuation of the speed of the hydraulic actuator due to the fluctuation of the load and improve the positioning accuracy.

[0009]

EXAMPLES Examples of the present invention are shown in FIGS.

In FIG. 2, reference numeral 1 denotes a hydraulic actuator driven by the liquid supplied from the proportional flow control valve 3, which is constituted by a hydraulic cylinder or the like as an example, and the hydraulic actuator 1 has a position detector 2 Are connected. The position detector 2 is composed of a stroke sensor, for example, and continuously detects the position of the hydraulic actuator 1 and sends a position signal to the control unit 4.

The control unit 4 includes a hydraulic actuator 1
The setting unit 5 for setting the drive pattern and the like is connected, and the control unit 4 drives the proportional flow control valve 3 to drive the hydraulic actuator based on the setting data from the setting unit 5 and the position signal from the position detector 2. Control 1

As shown in FIG. 3, the control unit 4 controls each data set by the setter 5, that is, the stop target position L.
3, deceleration start position L2, acceleration time T1, deceleration time T2,
The acceleration pattern VA (t) and the deceleration pattern VD (t), and the low speed holding time T3 calculated by the low speed holding time calculation circuit.
And a speed command generating circuit 40 that generates a speed command signal based on the data of the memory 44 and the position signal of the position detector 2, and a proportional flow rate by converting the speed command signal into a flow rate command signal. The command conversion circuit 41 for driving the control valve 3, the deceleration start position L2, the deceleration pattern VD (t), and the stop target position L3 stored in the memory 44.
From the stop position to the stop position, a low speed holding time calculation circuit 43 for calculating a time T3 for holding a predetermined low speed immediately before the stop, and a positioning for correcting the low speed holding time T3 from the stop position of the hydraulic actuator 1 and the stop target position L3. It is composed of a correction circuit 42.

FIG. 4 is a flow chart showing an example of control performed by the control unit 4, and FIG. 5 is a speed command generation circuit 4
FIG. 4 is a diagram showing the relationship between the speed command signal of 0 and time.
The flow of control will be described with reference to FIG.

In the flowchart of FIG. 4, in S1, the above-mentioned respective data instructed by the setting device 5 is read, and in S2.
Then, it is compared whether the data stored in the memory 44 and the data read from the setter 5 match. When the data of the setter 5 is changed, the deceleration pattern VD (t), the deceleration start position L2, and the stop target position L3 changed in S3.
On the basis of the
3 is calculated and stored in the memory 44.

If the start switch (not shown) of the setting device 5 is pressed in S4, the speed command generation circuit 4 is operated in S5.
0 generates a speed command signal as a function of time based on the acceleration pattern VA (t) of the memory 44, and the proportional flow rate control valve 3 opens based on the flow rate command signal converted by the command conversion circuit 41. The hydraulic actuator 1 is accelerated.

The acceleration of the hydraulic actuator 1 is continued until the deceleration start position L2 or a predetermined acceleration time T1 elapses (S6, S7). When the acceleration time T1 elapses in S7, the speed command signal at the end of acceleration is held in S8, and the hydraulic actuator 1 performs constant velocity motion.

When the position signal from the position detector 2 becomes equal to the deceleration start position L2 in S6 or S9, S10
The deceleration process starts at. In S10, a speed command signal as a function of time based on the deceleration pattern VD (t) stored in the memory 44 is generated by the speed command generation circuit 40, converted into a flow rate command signal by the command conversion circuit 41, and proportional flow rate control is performed. The valve 3 is gradually closed and the hydraulic actuator 1
Slows down.

In S11, it is determined whether or not a predetermined deceleration time T2 has elapsed. If the time T2 has not elapsed, the speed is further reduced in S10. If the deceleration time T2 has elapsed, the deceleration is stopped in S12 and the deceleration time T2 is reached. Holds the speed command signal at the time when has passed, and the hydraulic actuator 1 performs a uniform motion at a predetermined low speed.

The constant velocity motion at the low velocity is preset as the velocity immediately before the hydraulic actuator 1 is stopped.
The shock when the hydraulic actuator 1 is stopped is alleviated. This low speed holding time is the time T3 calculated in advance by the low speed holding time calculation circuit 43, and the predetermined low speed is held until the low speed holding time T3 elapses in S13.

When the elapse of time T3 is detected in S13,
In S14, the speed command generation circuit 40 sets the speed command signal to 0 and outputs it. The command conversion circuit 41 drives the proportional flow rate control valve 3 to close based on the speed command signal which has become 0 to stop the hydraulic actuator 1.

At this time, the hydraulic actuator 1 does not always stop at the target stop position L3, and when the actual stop position LS is smaller than the target stop position L3 as shown in FIG. 6 or as shown in FIG. Since the actual stop position LS may be larger than the target stop position L3, the low speed holding time T is lower than the stop position LS and the target stop position L3 after S15.
Correction of 3 is performed.

After the speed command signal is set to 0 in S14, in S15, the position correction circuit 42 waits for the stopped state of the hydraulic actuator 1 where the position signal from the position detector 2 becomes a constant value. A stop position error EL, which is the difference between the stop position LS and the target stop position L3, is obtained.

EL = LS-L3 Next, in S17, a correction value TE for correcting the predetermined low speed holding time T3 is obtained from the stop position error EL. The correction value TE is obtained from the following equation based on a preset constant K.

In TE = EL × K S18, the corrected low speed holding time T3 'is calculated from the calculated correction value TE.

T3 '= T3 + TE This calculated low speed holding time T3' is updated by storing it in the low speed holding time T3 of the memory 44 in S19, and the next driving of the hydraulic actuator 1 is based on the stop position error EL. Since it is performed by the corrected low speed holding time T3, it becomes possible to perform the positioning with high accuracy while suppressing the influence of the fluctuation of the temperature of the working liquid and the load of the hydraulic actuator.

In this way, the time T3 for holding the predetermined low speed is corrected based on the difference between the actual stop position LS and the target stop position L3, and the next driving is performed by the corrected low speed holding time T3. Therefore, it is possible to reduce the influence of the fluctuation of the temperature or the load of the hydraulic actuator 1 and perform highly accurate positioning by the open loop control device including the position detector 2 and the proportional flow rate control valve 3.

Although the proportional flow rate control valve 3 is disclosed as the control valve in the above embodiment, it is disclosed in JP-A-4-21018.
By adopting a valve for controlling the flow rate, which is disclosed in Japanese Patent Laid-Open No. 0-Gazette, while controlling the flow rate as the control valve, it is possible to suppress the fluctuation of the speed of the hydraulic actuator 1 due to the fluctuation of the load and the like. It is possible to improve the positioning accuracy.

Further, in the above embodiment, the acceleration pattern VA (t) and the deceleration pattern VD (t) are set at the time t.
Although it is disclosed as a linear function of, the speed pattern is not particularly limited, and any speed pattern can be used.

In the above embodiment, the acceleration pattern VA (t), the deceleration pattern VD (t), the deceleration start position L
2, stop target position L3, acceleration time T1, deceleration time T2,
The low speed holding time T3 is set for each cycle from the start to stop of the hydraulic actuator 1, and if the hydraulic actuator 1 reciprocates, at least two sets of respective data are set, and start and stop are performed. It suffices to set a plurality of sets of respective data corresponding to the cycle.

Although a hydraulic cylinder is disclosed as the hydraulic actuator 1 in the above embodiment, a swing type actuator or the like may be used although not shown, and a rotary encoder or the like may be applied as the position detector 2. Good.

In the above embodiment, the acceleration time T1
After the constant velocity motion is performed thereafter, when the vehicle reaches the deceleration position during the acceleration motion, it is possible to shift to the deceleration motion as shown in FIG. 8 by S6 in FIG.

[0032]

As described above, according to the present invention, the hydraulic actuator is held at a predetermined low speed for a predetermined time immediately before the hydraulic actuator is stopped, and then stopped, and then the hydraulic actuator is stopped at the actual stop position. Since it is corrected based on the difference between the target stop position and the preset stop position, and the next drive is performed by the corrected low speed holding time, the influence of temperature or load fluctuation can be reduced, and the configuration is simple. However, it is possible to perform highly accurate positioning.

Further, since a valve that controls the flow rate while estimating the passing flow rate is adopted as the control valve, it is possible to suppress the fluctuation of the speed of the hydraulic actuator due to the fluctuation of the load, and it is possible to improve the positioning accuracy. Becomes

[Brief description of drawings]

FIG. 1 is a diagram corresponding to a claim for the invention of claim 1.

FIG. 2 is a block diagram showing an embodiment of the present invention.

FIG. 3 is a block diagram of a control unit of the same.

FIG. 4 is a flowchart showing an example of control.

FIG. 5 is a graph showing a relationship between time and a speed command signal.

FIG. 6 is a graph showing a relationship between time and a speed command signal when LS <L3.

FIG. 7 is a graph showing a relationship between time and a speed command signal when LS> L3.

FIG. 8 is a graph showing a relationship between time and a speed command signal when reaching a deceleration start position during acceleration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic actuator 2 Position detector 3 Proportional flow control valve 4 Control unit 5 Setting device 20 Displacement amount detecting means 21 First speed command means 22 Deceleration position judging means 23 Second speed command means 24 Low speed judging means 25 Low speed holding Means 26 Stop position detecting means 27 Holding time correcting means 28 Drive stopping means 30 Control valve

Claims (2)

[Claims] 1. A hydraulic actuator receiving hydraulic pressure from a control valve, means for detecting a displacement amount of the hydraulic actuator, and a first speed command signal based on time based on a preset acceleration pattern. Means to send as a function,
Means for determining a deceleration position from the detected displacement amount, means for sending out a second speed command signal corresponding to a preset deceleration pattern based on the result of this judgment as a function of time, and the speed command signal A means for driving the control valve based on the above, a means for judging that the second speed command signal has been decelerated to a predetermined low speed, and a means for holding the low speed for a preset time based on the judgment result. , Means for setting the speed command signal to zero based on the passage of the holding time, means for detecting a stop position from the detected value of the displacement amount, and the means from the detected stop position and a preset stop target position A controller for a hydraulic actuator, comprising: a means for correcting a predetermined holding time. 2. The control device for a hydraulic actuator according to claim 1, wherein the control valve is a flow rate control valve including a flow rate estimating means.