JPH02292502A - Control device for fluid actuator - Google Patents

Abstract

PURPOSE:To remove deviation, which is caused by overshoot or temperature drift, by setting up a first integrating means with small gain which outputs control signals after integrating deviation signals, a second integrating means with large gain, and a switching means for the second integrating means which operates when a fluid actuator reaches a stationary state. CONSTITUTION:There are subtracter 3 which outputs deviation signals Ve created by subtracting speed inspection signals Vf from speed command signals Vi, a first integrating device 4 with small gain which integrates the deviation signals Ve, and a second integrating device 5 with large gain for removing drift. There are also a switching means 6 which switches the deviation signals Ve over to the first integrating device 4 when the oil pressure cylinder is in a non-stationary state while to a second integrating device 5 when in a stationary state, and an adding device 7 which outputs speed control signals Vc, which are calculated by adding signals from both integrating devices, to a control objective block 1. Consequently, overshoot is eliminated and stationary deviation by temperature drift can be made zero.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a control device that performs feedback control of a fluid actuator driven by working fluid passing through a solenoid valve based on a position detection signal thereof.

BACKGROUND ART Conventionally, as this type of control device, there is one shown in FIG. 4, for example. This control device selectively supplies pressurized oil from a hydraulic source 23 to the boats at both ends of the hydraulic cylinder 21 via an electromagnetic proportional control valve 22, and a sensor 24 that detects the speed of the rod 21a of the hydraulic cylinder 21. The speed detection signal f and the speed command signal Vi representing the target speed
is manually input to the controller 25, the controller 25 calculates the deviation Vi-Vf between both signals, performs compensation calculation regarding control characteristics on this, and outputs it to the solenoid 22a of the electromagnetic proportional control valve 22 as the speed control signal Vc. It is.

By the way, the viscosity of hydraulic oil decreases as the temperature rises, so when the opening degree of the electromagnetic proportional control valve 22 is constant, a larger amount of hydraulic oil is supplied to the hydraulic cylinder 21 as the temperature increases. Therefore, hydraulic cylinder 2! In order to keep the forward speed constant, the speed control signal Vc output from the controller 25 is increased as the temperature increases, as shown in FIG. Is it necessary to switch to the right symbol position? In other words, a drift occurs in the speed control signal Vc due to changes in oil temperature. Since it is difficult to analytically eliminate this temperature drift of the speed control signal Vc by detecting oil temperature changes, the controller 25 uses the deviation signal Vi-V in the controller 25.
An integral circuit for integrally compensating r is provided to output a speed control signal offset by temperature drift, thereby eliminating steady-state deviations in cylinder speed.

<Problems to be Solved by the Invention> However, the conventional control device described above has an integrating circuit in the controller 25, and this integrating circuit simply integrates the deviation signal, so there are the following problems. That is,
When the integral gain is increased so as to eliminate the steady-state deviation B due to temperature deformation, the control valve 22 is increased by the speed control signal Vc.
The response (cylinder speed) of the hydraulic cylinder 21 driven via the cylinder 21 produces an overburning point A with respect to the target speed Vi, as shown in FIG. 5(b). On the other hand, if the integral gain is made small, temperature drift cannot be eliminated.

Therefore, an object of the present invention is to separately install an integrating means for integrating the original detection signal in order to compensate for the control characteristics, and an integrating means for canceling the detection signal due to temperature drift in a control device. While maintaining the fluid actuator with good control characteristics without bar shoot etc.
It is an object of the present invention to provide a control device for a fluid actuator that can completely eliminate steady state deviation due to temperature drift.

Means for Solving the Problems> In order to achieve the above object, the fluid actuator control device of the present invention, as illustrated in FIG. Receiving a detection signal Vr from the sensor 24 that detects the operation,
The deviation signal Ve obtained by subtracting this detection signal vr from the command signal Vi is subjected to a compensation calculation and outputted to the solenoid valve 22 as the control signal Vc, and the deviation signal Ve is integrated to compensate for the control characteristics. and a second integrating means 4 with a large gain that integrates the deviation signal Ve and outputs it as a control signal Vc in order to eliminate the drift of the control signal due to temperature fluctuation. 5, a switch in which the first integrating means 4 is operated during unsteady operation of the fluid actuator 2I, and the second integrating means 5 is operated in place of the first integrating means 4 when the fluid actuator 21 reaches a steady state; It is characterized in that means 6 is provided.

Further, as illustrated in FIG. 2, the switching stage 6 of the control device is omitted, and the deviation signal Ve
Bypass filter 12 that allows only middle high frequency signals to pass through
It is also possible to configure a control device by providing a low-pass filter 13 that passes only the low-frequency signal in the deviation signal before the second integrating means 15.

Effect> Immediately after startup. When the fluid actuator 21 is in an unsteady state, such as immediately before stopping, the switching means 6 operates the I-th integration means 4 with a small gain, and the deviation signal Ve (-Vi-V
D is integrated, compensated to improve transient response characteristics, and output as a control signal Vc. Therefore, the response of the fluid actuator 21 driven by the working fluid passing through the electromagnetic valve 22 controlled by this control signal Vc is made to follow changes in the command signal without causing vibration or overshoot, improving control characteristics. . Next, the fluid actuator 2
1 reaches a steady state, the switching means 6 causes the second integrating means 5 with a large gain to operate in place of the first integrating means 4, integrates the deviation signal Ve, and performs compensation to eliminate temperature drift. and outputs it as a control signal Vc.

Therefore, there is no steady-state deviation in the movement of the fluid actuator 2I driven by the working fluid passing through the electromagnetic valve 22 controlled by this control signal Vc, and the fluid actuator 2
The movement of I changes in accordance with the command signal Vi.In addition, in a control device in which the switching means 6 is omitted and a high-pass filter l2 and a low-pass filter 13 are provided, the bypass filter changes according to the temperature drift in the deviation signal Ve. While the low-frequency signal is cut and output to the first integrating means 14, the low-pass filter 13 cuts the high-frequency signal in the deviation signal Ve and outputs it to the second integrating means 15. The integrating means 14 compensates for control characteristics, and the second integrating means I5 compensates for temperature drift. In addition, in this control device, since both the integrating means 14 and 15 operate at all times, it is possible to immediately respond to disturbances other than temperature drift even in a steady state.

Example Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 is a block diagram showing an example of a control system of a fluid actuator equipped with a control device of the present invention, and this control system includes the same hydraulic power source 23. Electromagnetic proportional control valve 22. The controller 2 includes a controlled object block 1 having a hydraulic cylinder 21 and a speed sensor 24 and outputting a speed detection signal Vf in response to a speed control signal Vc, and each block surrounded by a broken line in the figure.

The controller 2 subtracts the speed detection signal vr fed back from the speed sensor 24 of the controlled block I from the speed command signal Vi, and generates a deviation signal Ve (=Vi-
A subtracter 3 that outputs VD, a first integrator 4 with a small gain (for example, 5 or less) that integrates the deviation signal Ve to compensate for the control characteristics, and a first integrator 4 with a small gain (for example, 5 or less) to eliminate the drift of the speed control signal Vc due to temperature fluctuations. The deviation signal Ve from the second integrator 5 with a large gain (for example, 50 or more) that integrates the deviation signal Ve and the subtracter 3 is sent to the first integrator 4 during the unsteady operation of the hydraulic cylinder 21, When the second integrator 5
a switch means 6 for manually switching the integrators 4 and 5;
It is composed of an adder 7 which adds the signals from and outputs it to the controlled block l as a speed control signal Vc. Note that the switch 6 determines whether the operation of the hydraulic cylinder 21 is in a steady state based on changes in the speed command signal Vi and the speed detection signal vr, and automatically switches the deviation signal Ve. It looks like this.

The control of the hydraulic cylinder 21 by the controller 2 having the above configuration will be described next.

The speed sensor 24 in the controlled block 1 detects the speed of the rod 21a of the hydraulic cylinder 21 and outputs a speed detection signal Vr to the subtracter 3 of the controller 2. Subtractor 3
subtracts this speed detection signal vr from the speed command signal Vi and outputs a deviation signal Ve (=ViVr). Now, when the hydraulic cylinder 21 is in an unsteady operating state, such as immediately after starting or immediately before stopping, the switch means 6 detects this, switches, and inputs the deviation signal Ve to the first integrator 4. Then, the first integrator 4 having a small gain integrates the deviation signal Ve, performs compensation to improve the transient response characteristics, and outputs the result. Next, the adder 7 connects the second integrator 5
Since there is no output signal from the I-th integrator 4, the output signal from the I-th integrator 4 is outputted to the electromagnetic proportional control valve 22 of the controlled block 1 as the speed control signal Vc. Therefore, the hydraulic cylinder 2 is driven by the pressure oil passing through this control valve 22! response (
cylinder speed), vibration and overshoot (Fig. 5 (
(See b)) can be made to follow changes in the speed command signal Vi, and control characteristics such as transient response are improved.

Next, when the speed of the hydraulic cylinder 21 reaches a steady operating state where the speed is substantially constant, the switch 6 detects this, switches, and inputs the deviation signal Ve to the second integrator 5. Then, the second integrator 5 having a large gain integrates the deviation signal Ve, performs compensation to eliminate temperature drift, and outputs the result. Next, the adder 7 adds the output signal from the second integrator 5 and the final output signal integrally compensated by the first integrator 4 during operation, but the latter signal is mostly Since the output signal is 0, the output signal created by integrating the former large gain is output to the control valve 22 as the speed control signal Vc. Therefore, the steady deviation of the speed of the hydraulic cylinder 21 driven by the pressure oil passing through the control valve 22 (see B in FIG. 5(b)) becomes 0, and the cylinder speed changes in accordance with the speed command signal Vi. I will do it.

FIG. 2 is a block diagram showing another embodiment of the control device of the present invention. This control device omits the switch means 3 of the controller 2 described in FIG.
A bypass filter 12 and a low-pass filter 13 are provided between the integrator 14, the second integrator 15, and the subtracter 3, respectively, and the output signal of the adder 7 is amplified to generate the speed control signal Vc.
An amplifier 16 is provided to output the signal as follows. As shown in FIG. 3(a), the bypass filter 12 receives the deviation signal Ve.
Only the original signal components whose frequencies are F1 or higher are passed to the first integrator 14, and the low-pass filter 13 is configured as shown in FIG.
As shown in b), only signal components whose frequency due to temperature drift in the deviation signal Ve is F or less are passed to the second integrator 15. The first integrator 14 integrates the respective signal components to compensate for the control characteristics, and the second integrator 15 integrates the respective signal components to compensate for temperature drift. Note that both integrators 14.1
It does not matter whether the gain of 5 is large or small.

Therefore, this control device also operates in the same manner as the embodiment described in FIG. 1, and the speed control characteristics such as the transient response of the hydraulic cylinder 21 are improved, and the steady-state deviation of the speed becomes O. Furthermore, in this control device, since both integrators 1, 4, and 5 operate constantly, temperature drift can be eliminated even in an unsteady state, and deviations caused by disturbances other than temperature drift can be compensated for even in a steady state. Hydraulic cylinder 2
The rigidity at the time of positioning can be increased, and desired control characteristics can always be maintained.

In the above embodiment, the controller 2 is configured as an analog circuit, but it can also be digitized using a known method and configured as software such as an integral program or a filter program that drives a computer serving as a controller.

Moreover, the fluid actuator is not limited to the hydraulic cylinder of the embodiment, but the control target can also be the position of the fluid actuator.

Furthermore, it goes without saying that the present invention is not limited to the illustrated embodiment.

Effects of the Invention> As is clear from the above description, the fluid actuator control device of the present invention is capable of controlling the deviation signal Ve between the operating state detection signal vr and the command signal Vi of the fluid actuator driven by the working fluid passing through the electromagnetic valve. In the control signal Vc that is compensated for and output to the solenoid valve as the control signal Vc, the deviation signal Ve in an unsteady state is integrated by the first integrating means using a switching means, a bypass filter, or a low-pass filter to obtain a transient response. While compensating the characteristics, the deviation signal Ve in the steady state is integrated by the second integrating means to eliminate temperature drift, and the output signals from both integrating means are output as the control signal Vc, so that the fluid actuator While maintaining good control characteristics without overshoot etc., the steady-state eccentric system due to temperature drift can be reduced to zero.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a control system of a fluid actuator equipped with one embodiment of the control device of the present invention, FIG. 2 is a similar plot diagram with another embodiment, and FIG. Figure 2 is a diagram showing the characteristics of the filter, Figure 4 is an overall diagram showing the conventional control system, and Figures 5 (a) and (b) are diagrams showing the temperature drift of the conventional control signal and the response of the cylinder speed. be. 1...Controlled object, 2...Controller, 3...Subtractor, 4.14...1th integrator, 5.15...2nd
Integrator, 7... Addition device, 12... High-pass filter, 13... Low-pass filter, Vi... Speed command signal, vr... Speed detection signal, Ve... Deviation signal, V
c...Speed control signal. Patent applicant Agent: Daikin Industries, Ltd.
Person Patent attorney Aoyama Aoyama and others Figure 3 Figure 5

Claims (2)

[Claims] (1) A sensor (24) that detects the operation of a fluid actuator (21) driven by working fluid passing through a solenoid valve (22).
) and receives the detection signal (Vf) from
) is subtracted from the command signal (Vi) to obtain the deviation signal (Ve
) in a fluid actuator control device that performs a compensation calculation on the control signal (Vc) and outputs it to the electromagnetic valve (22) as a control signal (Vc). ), and a second integrating means (4) with a large gain, which integrates the deviation signal (Ve) and outputs it as a control signal (Vc) in order to eliminate drift due to temperature fluctuations, etc. (5), and when the fluid actuator (21) is in unsteady operation, the first
The integrating means (4) is operated and the fluid actuator (21
) reaches a steady state, switching means (6) operates the second integrating means (5) instead of the first integrating means (4);
) A control device for a fluid actuator. (2) A sensor (24) that detects the operation of a fluid actuator (21) driven by the working fluid passing through a solenoid valve (22).
) and receives the detection signal (Vf) from
) is subtracted from the command signal (Vi) to obtain the deviation signal (Ve
) in a control device for a fluid actuator that performs a compensation calculation on the signal and outputs it as a control signal (Vc) to the solenoid valve (22), the bypass filter (12) receiving the deviation signal (Ve).
) and the bypass filter (1) to compensate for the control characteristics.
A first integrating means (14) that integrates the output signal of 2) and outputs it as a control signal (Vc), a low-pass filter (13) that receives the deviation signal (Ve), and A control device for a fluid actuator, characterized in that a second integrating means (15) is provided for integrating the output signal of the low-pass filter (13) and outputting it as a control signal (Vc).