JPH0799163B2 - Fluid actuator control device - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a control device for a fluid actuator, which controls switching of operating position, speed, and pressure of the fluid actuator by one control valve and three feedback control loops.

[Prior art]

Conventionally, as a control device for this type of fluid actuator,
For example, the one shown in FIG. 6 is known (Japanese Patent Application No. 2-20193). This control device includes a servo controller 63 that outputs a control signal to a solenoid 62 of a servo valve (not shown) that supplies and discharges pressure oil from a hydraulic source to the hydraulic cylinder 61,
The hydraulic cylinder 61 includes a position detector 64 and a differentiator 65 that differentiates the position detection signal (b) of the position detector 64 and outputs a speed detection signal (c). The servo controller 63 includes a position subtractor 66 for subtracting the position detection signal (b) from the position command signal (a),
A position controller 67 for compensating this output signal, and a speed subtractor for subtracting the speed detection signal (c) from this output signal.
68, a speed controller 69 for compensating this output signal, a differential pressure detector 70 for detecting the pressure difference between the hydraulic oils at both ends of the hydraulic cylinder 61, and this differential pressure detection signal (d) for the speed A subtractor 71 for differential pressure that subtracts from the output signal of the controller 69,
It comprises a differential pressure controller 72 for compensating this output signal, and a voltage / current converter 73 for converting this output signal into a current signal and outputting it to the solenoid 62 as a control signal. That is, the servo controller 63 includes a differentiator 65, a speed subtractor 68, and a speed controller 69 in a position feedback control main loop including a position detector 64, a position subtractor 66, and a position controller 67. Minor loop of speed feedback control, differential pressure detector 70, differential pressure subtractor 71, differential pressure controller
The minor loop of the differential pressure feedback control consisting of 72 is configured, and the speed and the differential pressure are regulated by the gain adjustment of the speed controller 69 and the differential pressure controller 72 while mainly controlling the position control.

[Problems to be Solved by the Invention]

However, the above-mentioned conventional fluid actuator control device performs only position control in the main feedback loop and only regulates speed and differential pressure in the minor feedback loop.Therefore, command signals of speed and pressure are externally supplied. Enter and hydraulic cylinder 61 via servo valve
However, there is a drawback that the operating speed and pressure cannot be directly controlled, and the hydraulic cylinder cannot be controlled with a degree of freedom. To solve this drawback, for example, the speed subtracter 6
8. The speed controller 69 is arranged in parallel with the position subtractor 66 and the position controller 67, and the speed subtractor 68 obtains a deviation signal between the speed command signal and the speed detection signal (c) from the outside. The signal is compensated by the speed controller 69, and the output signal of either the position controller 67 or the speed controller 69 is selected as necessary by the control changeover switch, and the differential pressure subtractor 71 +
A method of outputting to the side can be considered. However, even with this method, only one of the position and the speed of the hydraulic cylinder 61 can be feedback-controlled, and at that time the feedback control of the other is ineffective.Therefore, when an unexpected situation occurs during operation, selection of the control changeover switch can be performed. If mistaken, the hydraulic cylinder 61 may run away or be damaged. Also, when the position changeover or speed changeover is selectively performed with the control changeover switch, the control signal to the solenoid 62 of the servo valve becomes discontinuous depending on the internal state of the feedback loop which was on the non-control side until the changeover. Cylinder 61
However, there is a problem in that the malfunction of overshoot or undershoot occurs in the operation of. Also, with this technique,
The operating pressure cannot be directly controlled because it is still controlled by the minor field back loop. Therefore, an object of the present invention is to monitor the remaining two detection signals when controlling any one of the position, velocity, and pressure, so that the remaining two uncontrolled control amounts of the fluid actuator increase abnormally. The present invention provides a control device for a fluid actuator capable of preventing damage to the fluid actuator and the like, and at the time of controlling the position, speed, and pressure of the fluid actuator by mutually switching these control loops, a control loop on the operating side. A new method of inputting and holding the control signal output from the controller to the non-operating side control loop realizes smooth and continuous switching between these controls over a wide range of position, velocity, and pressure. Another object of the present invention is to provide a control device for a fluid actuator capable of performing the above.

[Means for Solving the Problems]

In order to achieve the above object, a control device for a first fluid actuator according to the present invention, as illustrated in FIG.
The detection signals Ss, Vs, Ps from the position, speed, and pressure detectors 5, 10, 13 of the fluid actuator 2 are converted into command signals Sr, Vr, Pr by the deceleration and pressure comparison means 6, 8, 14, respectively. The control valve 4 provided on the pressure line 3 of the fluid actuator 2 selects one of the three control signals by the switch means 16 by outputting the control signal of the position, speed and pressure by subtracting from the control valve 4.
In the case of one of the control signals selected, the command signals relating to the remaining two control amounts and their detection signals are compared with each other, and if there is a control amount whose detection signal is larger than the command signal, A switching control means 17 for switching the switching means 16 to the side of the control amount is provided. Further, the second fluid actuator control device of the present invention, as illustrated in FIG. 4, commands detection signals from the detectors 26, 27 and 28 of the position, speed and pressure of the fluid actuator 21, respectively. The position, velocity and pressure deviation signals obtained by subtraction from the signal are compensated by the respective compensating means 34, 44 and 54 to obtain position, velocity and pressure control signals, and any one of the above three control signals is obtained. In what selects and outputs to the control valve 22 provided in the pressure line of the fluid actuator 21,
When the self control signal is selected for each of the position, velocity, and pressure compensating means 34, 44, 54, the self-feedback loop 34a, 44a, 54a of the compensating means is cut off, and the other two compensating means are cut off. Circuit from the output side of the to the input side of the compensation means
34b, 44b, 54b is cut off, and at the time of control when other control signals are selected, the above circuits 34b, 44b54b and the above loop
First switch means 36, 37, 46, 47, 5 for connecting 34a, 44a, 54a
6,57 :, while the other control signal is selected, the circuit for the deviation signal coming into the compensating means is shut off, and the circuit for the control signal going to the control valve 22 is shut off. In addition, the second switch means 32, 35, 42, 45, 52, 55; A, B, C for connecting the circuit for the deviation signal and the circuit for the control signal at the time of control in which its own control signal is selected are It is characterized by being provided.

[Action]

For example, at the time of speed control, a speed control signal obtained by subtracting the speed detection signal Vs from the speed command signal Vr by the comparison means 8 is output to the control valve 4 via the switch means 16, whereby the speed of the fluid actuator 2 is increased. Is controlled.
At this time, the switching control means 17 compares the position command signal Sr and the position detection signal Ss, and the pressure command signal Pr and the pressure detection signal Ps, respectively, and when the detection signal is larger than the command signal, the control signal side The switch means 16 is switched. For example, when the position detection signal Ss is larger than the position command signal Sr, the position of the fluid actuator 2 is controlled, and the position is suppressed within the position represented by the position command signal Sr. Even during position or pressure control, the switching control means 17 compares the command signal and the detection signal with respect to the remaining two control amounts that are not control targets, that is, speed and pressure or speed and position, respectively, and the latter is larger than the former. The switch means 16 is switched to the side of the controlled variable. For example, the speed detection signal Vs
Is larger than the speed command signal Vr, the above switch means
16 is switched to the speed control signal side, the speed of the fluid actuator 2 is controlled, and the speed is suppressed below the speed value represented by the speed command signal Vr. In the second control device of the present invention, for example, at the time of speed control in which the speed control signal from the speed compensating means 44 is selected,
The second switch means 42, 45; B of the speed compensating means 44 are turned on, and the first switch means 36, 37, 56, of the other compensating means 34, 54.
57 ;, is turned on. Then, the speed compensation means 4
The speed deviation signal, which is the difference between the speed command signal Vr and the speed detection signal Vs, is input to 4 and the self-field back loop 44a is cut off (by the first switch means 46). The speed control signal obtained by performing compensation on the control valve 22 and the position and pressure compensating means 34,5
Output to the input side of 4 via the first switch means 37 and 57 respectively, and the speed of the fluid actuator 21 is field-back controlled by the control valve 22 and the speed detector 27. Further, the position and pressure deviation signals are not inputted to the position and pressure compensating means 34 and 54 for turning off the second switch means 32, 35, 52, 55; A and C, and these compensating means 34 , 54 is located on the input side of the speed compensation means 44 in which the first switch means 47 is off,
The speed control signals input to the position and pressure compensating means 34 and 54 without the pressure control signal being input to the self-field back loops 34a and 54a conducted by the first switch means 36 and 56, respectively. Is held through. Next, when the control mode is switched from speed control to pressure control, for example, the second switch means 52, 55 of the pressure compensating means 54;
C is turned on, the first switch means of the other compensating means 34,44
36,37,46,47 ;, are turned on. Then, the speed control signal immediately before being held by the pressure compensating means 54 is output to the control valve 22 as a pressure control signal. Therefore, in spite of the presence of the delay element included in the pressure compensating means 54, delay or discontinuity does not occur in the output pressure control signal, the pressure response of the fluid actuator 21 is improved, and a wide pressure range is achieved. A smooth and continuous transition to pressure control without overshoot or undershoot is realized. Thus, the pressure of the fluid actuator 21 is field-back controlled by the control valve 22 and the pressure detector 28, and the pressure control signal at this time is sent from the second switch means 55 of the pressure compensating means 54 to the first switch. means
37 and 47 are input to the input side of the speed and position compensating means 34 and 44, respectively, and held by the self-field back loops 34a and 44a. Furthermore, switching from pressure control to position control, for example,
By the same process as described above, smooth and continuous operation is performed with good position response over a wide position range. In this way, smooth and continuous switching between these controls is achieved over a wide range of positions, velocities and pressures.

【Example】

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 shows an example of a control device for a first fluid actuator according to the present invention. This control device has pressure lines 3a, 3b from a hydraulic pressure source 1 to a hydraulic cylinder 2 having a load.
In addition to the servo valve 4 serving as a control valve, the position subtractor 6 takes the difference between the position command signal Sr and the position detection signal Ss from the position sensor 5 provided in the hydraulic cylinder 2 to obtain this position deviation signal. The position compensating circuit 7 compensates for a position control signal, and the speed subtractor 8 differentiates the speed command signal Vr and the position detection signal Ss as a speed detector.
The difference from the speed detection signal Vs from 10 is taken, and this speed deviation signal is compensated by the speed compensating circuit 9 to obtain a speed control signal. Further, the control device is configured such that the difference between the detection signals from the pressure sensors 11 and 12 provided on the pressure lines 3a and 3b, respectively (the hydraulic cylinder 2
The differential pressure at both ends of the pressure difference signal is obtained by the differential pressure amplifier 13 as the pressure detection signal Ps, the difference between the pressure command signal Pr and the pressure detection signal Ps is calculated by the pressure subtractor 14, and the pressure deviation signal The compensation circuit 15 compensates for the pressure control signal. The output side of the compensating circuits 7, 9, 15 is switched by a limit switch operating at a specific position of the hydraulic cylinder 2, a timer or manually, and is switched by a switching control circuit 17 which will be described later. A control changeover switch 16 for selecting any of the three control signals and sending it to the solenoid 4a of the servo valve 4 is provided. Further, when one of the control signals for position, speed and pressure is selected by the control changeover switch 16, the command signals Sr, Vr, Pr relating to the remaining two control amounts and their detection signals Sr, Vs, Ps are compared respectively. Then, the changeover control circuit 17 for changing over the control changeover switch 16 to the side of the control amount whose detection signal is larger than the command signal is provided. The speed detection signal Vs from the differentiator 10 is fed back to the position compensation circuit 7, and the pressure detection signal Ps from the differential pressure amplifier 13 is fed back to the position compensation circuit 7 and the speed compensation circuit 9 as minor feedback loops. The performance of position and speed control is improved. The operation of the hydraulic cylinder control device having the above configuration will be described below with reference to FIG. Now, during speed control in which the control changeover switch 16 is switched as shown in FIG. 1, for example, the speed control signal obtained by subtracting the speed detection signal Vs from the speed command signal Vr by the speed subtractor 8 is the servo valve 4 Is output to the solenoid 4a, and the speed of the hydraulic cylinder 2 is feedback-controlled. In addition,
At this time, the speed compensation circuit 9 is subjected to minor feedback by the pressure detection signal Ps, so that the control performance is improved. Then, the switching control circuit 17 performs the steps shown in FIG.
If it is determined to be no in S1, it is determined to be affirmative in step S6 and is determined in step S7.
In step S7, the pressure detection signal Ps is compared with the pressure command signal Pr, and if the former is larger than the latter, step
While proceeding to S8, the control changeover switch 16 is switched to the pressure compensating circuit 15 side, while if the former is smaller than the latter, it proceeds to step S9. Then, in step S9, the position detection signal Ss and the position command signal Sr are compared, and if the former is larger than the latter,
In step S10, the control switch 16 is switched to the position compensation circuit 7 side. Therefore, for example, the position detection signal Ss
Is larger than the position command signal Sr, the hydraulic cylinder 2
Is controlled by the servo valve 4 operated by the position control signal passing through the switched control changeover switch 16, and thereafter the position is controlled so as to follow the position command signal Sr. Further, during position control, minor feedback is applied by the speed detection signal Vs, so that control performance can be improved. Thus, even if an unexpected situation occurs during the speed control operation, the operating position is automatically suppressed to a value equal to or less than the value represented by Sr of the position command signal, and the hydraulic cylinder does not run away or break. Further, if the position command signal Sr is set to a value equal to or larger than the stroke limit of the hydraulic cylinder, it is always judged as negative in steps S9 and S13, so that only speed or pressure control can be performed. Needless to say, the process returns to step S1 if the determination in step S9 is negative. Next, when the control changeover switch 16 is switched to a position or pressure which is different from that shown in FIG.
For one controlled variable, speed and pressure, or speed and position,
Similarly to the above, the changeover control circuit 17 compares the detection signal and the command signal in accordance with the flowchart shown in FIG. 2, and the former switches the control changeover switch 16 to the side of the control amount which becomes larger than the latter. For example, the speed detection signal Vs is the speed command signal Vr
If it is larger than the above, the control changeover switch 16 is switched to the speed compensating circuit 9, and the hydraulic cylinder 2 is controlled by the servo valve 4 which is operated by the speed control signal thereafter so that the speed follows the speed command signal Vr. Controlled. Therefore, even if an unexpected situation occurs during position or pressure control operation, the operating speed and operating pressure or position are automatically suppressed below the values indicated by the respective command signals, and the hydraulic cylinder 2 runs away or is damaged. There is nothing to do. Further, if the speed command signal Vr is set to a speed higher than the capacity of the hydraulic power source 1, only position or pressure control can be performed. In the above embodiment, the pressure sensors 11 and 12 are provided on the pair of pressure lines 3a and 3b, respectively, and the difference between the detection signals of both pressure sensors is obtained by the differential pressure amplifier 13 and used as the pressure detection signal Ps. It is possible to prevent stick-slip and reduce the influence of the dead zone of the servo valve. In order to make it easier to determine which one of the position, speed, and pressure controls is operating, a light emitting diode or the like may be linked to the control changeover switch 16, and it is possible to perform remote determination by the output signal of the linked transistor. You can also Further, the switching control means of the present invention is not limited to the switching control circuit 16 which is the hardware of the embodiment, but may be software such as a program of a microprocessor. FIG. 3 is a block diagram showing a modified example of the control device for the hydraulic cylinder of FIG. In this control device, the hydraulic cylinder shown in FIG. 1 is used as a single rod hydraulic cylinder 2 ', and one load port of a 4-port servo valve is closed to become a 3-port servo valve 4', and the hydraulic cylinder 2'is also used. Rod side port to pressure line 3b
Is directly connected to the hydraulic pressure source 1 and the hydraulic cylinder 2'is moved forward by the pressure receiving area difference at the symbol position on the right side of the drawing of the servo valve 4 ', and the head side port is connected to the tank at the symbol position on the left side of the drawing. The hydraulic cylinder 2'is moved back. Further, the pressure sensor 12 of FIG.
A subtractor 18 is provided in place of 10, and the pressure Ph of the head side port of the hydraulic cylinder 2 ′ detected by the pressure sensor 11 by the subtractor 18 and the pressure Pp of the hydraulic power source 1 are set to the pressure receiving area on the rod side / head side. The difference from the value obtained by multiplying the ratio Ar / Ah (actually measured pressing force per unit area) is obtained, and this is output to the pressure subtractor 14 as a pressure detection signal Ps. The configuration of the control device is exactly the same as that of the control device described in FIG. 1 except the above configuration, and the same members are denoted by the same reference numerals and the description thereof will be omitted. Therefore, the control device shown in FIG. 3 also operates in the same manner as described with reference to FIG. 1, and can prevent an abnormal increase in the operating position, speed, and pressure of the hydraulic cylinder 2'before it happens, causing the hydraulic cylinder to run out or to push excessively. Damage due to pressure can be eliminated. The control valve of the present invention is not limited to the servo valve of the embodiment,
It may be an electromagnetic proportional type flow direction control valve or the like, and the fluid actuator of the present invention is not limited to the hydraulic cylinder of the embodiment but may be a pneumatic cylinder or the like. FIG. 4 is a block diagram showing an example of a control device for a second fluid actuator according to the present invention. This control device includes a hydraulic cylinder 21 as a fluid actuator, a servo valve 22 as a control valve provided on a pressure line (not shown) of the hydraulic cylinder, and an operating position, speed, and pressure of the hydraulic cylinder 21 for the servo control. It is composed of position, velocity, and pressure control loops 23, 24, and 25 that are feedback-controlled via the valve 22, respectively. The position control loop 23 is a position sensor 26 that detects the operating position of the hydraulic cylinder 21, and a deviation subtracter 31 that outputs a position deviation signal by subtracting the position detection signal from the position sensor 26 from the position command signal, The signal input from the deviation subtractor 31 through the second input switch 32 and the input side adder 33 is compensated with a predetermined compensation value, and the second output switch 35 and the output side adder 29 are used as position control signals. A position compensation circuit 34 for outputting to the servo valve 22 is provided. On the other hand, the speed control loop 24 is, as a speed detector, a differentiator 27 that differentiates the position detection signal and a deviation subtracter that subtracts the speed detection signal from the differentiator 27 from the speed command signal to output a speed deviation signal. And a signal input from the deviation subtractor 41 through the second input switch 42 and the input side adder 43 is compensated with a predetermined compensation value, and the second output switch 45 and the above-mentioned signal are output as a speed control signal. A speed compensating circuit 44 for outputting to a solenoid (not shown) of the servo valve 22 via an output side adder 29 is provided. The pressure control loop 25 includes a pressure sensor 28 for detecting the operating pressure of the hydraulic cylinder 21, a deviation subtracter 51, an input second switch 52, an input side adder 53, and a pressure compensating circuit 54, which are similar to those described above. The second output switch 55 is provided. Further, the position control loop 23 is a self-feedback loop that returns the output of the position compensation circuit 34 to the input side adder 33.
A hold loop for guiding the outputs of the speed and pressure compensating circuits 44, 54 to the input-side adder 33 through the output-side adder 29 while having the self-feedback first switch 36 in 34a.
The holding first switch 37 is provided at 34b. The speed control loop 24 also has a self-feedback first switch 46 in the self-feedback loop 44a of the speed compensating circuit 44, and guides the outputs of the other compensating circuits 34, 54 to the input side adder 43. The hold loop 44b has a first hold switch 47. Similarly, in the pressure control loop 25, the self-feedback loop 54a is provided with the first switch 56 for self-feedback, and the hold loop 54b is provided with the first hold-use first switch 56.
Each has a switch 57. Then, the first switches 36, 37, 46, 47, 56, 57 (in the figure, consisting of analog switches of the control loops 23, 24, 25)
, Reference) are respectively cut off when the servo valve 22 is controlled by a control signal of its own control loop, and are turned on when the servo valve 22 is controlled by a control signal of another control loop. On the other hand, the second switch 32, 35, 42, 4 consisting of analog switches of each control loop
5,52,55 (see A, B, C in the figure) conducts when controlling its own control mode and shuts off when controlling other control modes
It constitutes a switch means. The operation of the hydraulic cylinder control device configured as described above is as follows. For example, when the speed of the hydraulic cylinder 21 is controlled, the second switches 42 and 45 (B) of the speed control loop 24 are turned on, the first switches 46 and 47 () are turned off, and the other control loops 23 and 25 are controlled. The first switches 36, 37; 56, 57 (;) are turned on, and the second switches 32, 35; 52, 55 (A; C) are turned off. Then, the speed control loop 24 operates. That is, the deviation subtractor 41
Calculates the deviation between the speed command signal and the speed detection signal from the differentiator 27, and outputs this speed deviation signal to the speed compensation circuit 44 via the second input switch 42 and the input side adder 43. At this time, the first switch 46 of the self-feedback loop 44a and the first switch 47 of the hold loop 44b.
Are both off, the speed deviation signal is directly input to the speed compensating circuit 44. Next, the speed compensating circuit 44 compensates the inputted speed deviation signal with a predetermined compensation value to obtain a speed control signal, and the speed control signal is passed through the output second switch 45 and the output side adder 29. Servo valve 22
Output to. At this time, since the output second switches 35 and 55 of the other control loops 23 and 25 are off, the speed control signal is directly input to the servo valve 22, and the speed of the hydraulic cylinder 21 is changed to the speed command by the servo valve 22. Feedback control is performed so as to follow the signal. Further, the speed control signal is sent from the speed compensating circuit 44 to the output side adder 29 and the holding first switches 37 and 57 of the hold loops 34b and 54b of the other control loops 23 and 25, respectively. Since the second input switches 32 and 52 of both control loops are turned off by being guided to 33 and 53, the first self-feedback switches 36 and 54a of the self-feedback loops 34a and 54a,
The signal input via 56 is subtracted and input to the position and pressure compensating circuits 34 and 54, respectively. Both compensating circuits 34 and 54 compensate the input signals with a predetermined compensation value and output them as position and pressure control signals, but both control signals are output again because the second output switches 35 and 55 are off. It is fed back to the input side adders 33 and 53 through the self-feedback loops 34a and 54a, respectively. In other words, the compensating circuit for speed of the speed control loop 24 that is the operating side
The speed control signal input from the non-operating side position / compensation circuit 34/54 of the pressure control loop 23/25 from 44 is the position / pressure control to be output next via the conducting self-feedback loop 34a / 54a. It is held as a signal. Next, in order to switch the hydraulic cylinder 21 to, for example, pressure control, the second switches 52 and 55 (C) of the pressure control loop 25 are turned on, the first switches 56 and 57 () are turned off, and another control loop is set. 23,24 first switch 36,37; 46,47
(;) Is turned on and the second switch 32,35; 52,55 (A;
Turn off B). Then, the pressure control loop 25 operates, and the speed control signal immediately before held in the pressure compensating circuit 54 is output as the pressure control signal by the second switch 55 for output.
Is output to the servo valve 22. Therefore, despite the presence of the delay element normally included in the pressure compensating circuit 54, delay or discontinuity hardly occurs in the output pressure control signal, the pressure response of the hydraulic cylinder 21 is improved, and a wide pressure range is achieved. A smooth and continuous transition to pressure control without overshoot or undershoot over the range can be realized. continue,
Deviation subtractor 53, second input switch 52, input side adder 53,
Pressure compensating circuit 54, output second switch 55, servo valve 22,
Pressure control loop 25 via hydraulic cylinder 21 and pressure sensor 28
Thus, feedback control is performed so that the pressure of the hydraulic cylinder 21 follows the pressure command signal. Further, the pressure control signal passes through the hold loops 34b, 44b of the other control loops 23, 24 in the same manner as described above, and the self-feedback loops 34a, 4b.
The position and speed control signal to be output next is held by 4a. Switching between the speed and pressure control modes other than those described above is also smoothly and continuously performed with good responsiveness over a wide range through the same procedure. Figure 5 shows
In such position, velocity, and pressure control modes,
This is a collective representation of the on and off states of the first and second switches. The position, velocity and pressure compensation circuits 34, 44 and 54 in FIG. 4 are used as integrator circuits, and the position, velocity and pressure detection signals are respectively multiplied by a constant value and the multiplication result signals are fed from the respective integrator circuits. It is also possible to add an auxiliary feedback loop of a proportional element composed of an adder for adding to the control signal of 1 and an adder for adding the multiplication result signal to the signal of each hold loop. By doing so, a so-called IP control system is realized, and due to the contribution of the proportional element feedback signal to the control signal, good mutual switching of control modes can be achieved even if the load of the hydraulic cylinder 21 has a strong proportional element. it can. Although the hydraulic actuator is the hydraulic cylinder 21 in the above embodiment, it may be a hydraulic motor or a pneumatic cylinder. The control valve may be an electromagnetic proportional type flow direction control valve instead of the servo valve 22.

【The invention's effect】

As is apparent from the above description, the first control device of the present invention is capable of controlling the position, speed, and pressure control signals by subtracting the speed detection signals from the position, speed, and pressure command signals. In order to control the position, speed or pressure of the fluid actuator by selecting either by the switch means to the control valve and controlling the position, speed or pressure, one of the above-mentioned control signals and the command signal relating to the remaining two control variables and the detection thereof. The signals are respectively compared by the switching control means, and if the detected signal has a control amount larger than the command signal, the switch device is switched to the side of the control amount. It is possible to prevent the abnormal increase of the remaining two control variables under any of the control modes of position, speed and pressure by setting the regulation value of, and the abnormal increase in these causes the fluid actuator etc. Failure to be able to eliminate that. Further, the second control device of the present invention switches and controls the operation of the fluid actuator by three feedback control loops of position, speed, and pressure and one control valve, and each feedback control loop includes a first switch means. The second switch means is provided so that when any one of the position, speed and pressure control signals is selected, the deviation signal only for the selected compensating means is supplied to output the control signal and the compensating means is provided. The control signals output to the remaining two compensating means are held by the remaining compensating means, so that the smooth and continuous control modes can be interoperated with good response over a wide position, speed and pressure range. Switching between can be realized.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a control device for a first fluid actuator according to the present invention, FIG. 2 is a flowchart showing the operation of the above embodiment, FIG. 3 is a diagram showing a modification of FIG. 1, FIG. 4 is a diagram showing an embodiment of a control device for a second fluid actuator according to the present invention, and FIG. 5 is an on / off state of the first and second switches in each control mode of the embodiment of FIG. FIG. 6 is a view showing a conventional hydraulic cylinder control device. 2 ... hydraulic cylinder, 4 ... servo valve, 5 ... position sensor, 6 ... position subtractor, 7 ... position compensation circuit, 8 ... speed subtractor, 9 ... speed compensation circuit, 10 ... Differentiator, 11, 12 ... Pressure sensor, 13 ... Differential pressure amplifier, 14 ... Pressure subtractor, 15 ... Pressure compensation circuit, 16 ... Control changeover switch, 17 ... Changeover control circuit , 21 …… hydraulic cylinder, 22 …… servo valve, 23 …… position control loop, 24 …… speed control loop, 25 …… pressure control loop, 26 …… position sensor, 27 …… differentiator, 28 …… pressure Sensor, 29 …… Output side adder 31,41,51 …… Deviation subtractor 33,43,53 …… Input side adder 36,37,46,47,56,57; ………… 1st switch , 32,35,42,45,52,55; A, B, C …… Second switch, 34a, 44a, 54a …… Self-feedback loop. 34b, 44b, 54b ... Hold loop.

Claims (2)

[Claims] 1. Comparing means for position, deceleration and pressure (6,8,14)
By subtracting the detection signals (Ss, Vs, Ps) from the position, velocity and pressure detectors (5,10,13) of the fluid actuator (2) from the respective command signals (Sr, Vr, Pr) Position, speed,
Each pressure control signal is output, and any one of the three control signals is selected by the switch means (16) to the control valve (4) provided on the pressure line (3) of the fluid actuator (2). In the control device of the fluid actuator for output, when one of the control signals is selected, the command signals relating to the remaining two control amounts are compared with their detection signals, respectively, and the control amount having a detection signal larger than the command signal is detected. if there is,
A control device for a fluid actuator, comprising a switching control means (17) for switching the switching means (16) to the side of the control amount. 2. A fluid actuator (21) position, velocity,
The compensation signals (34, 44, 54) are applied to the deviation signals of position, velocity and pressure obtained by subtracting the detection signals from the pressure detectors (26, 27, 28) from the respective command signals. Position with compensation,
A control device for a fluid actuator, which uses as control signals for speed and pressure, selects one of the above three control signals and outputs the selected control signal to a control valve (22) provided in a pressure line of the fluid actuator (21), When the self-control signal is selected for each of the position, velocity, and pressure compensating means (34, 44, 54), the self-feedback loop (34a, 44a, 54a) of the compensating means is cut off, and the other The circuit (34b, 44b, 54b) from the output side of the two compensating means to the input side of the compensating means is cut off, and at the time of control when another control signal is selected, the circuit (34b, 44b, 54b)
b) and the first switch means (36, 37, 46, 47, 56, 57 :,) for connecting the loop (34a, 44a, 54a) are provided, while other control signals are selected at the time of control, The circuit for the deviation signal coming into the compensating means is cut off, and the circuit for the control signal going out to the control valve (22) is cut off.
Second control means (32, 35, 42, 45, 52, 55; A, B, C) for connecting the circuit for the deviation signal and the circuit for the control signal is provided at the time of control when the self control signal is selected. A controller for a fluid actuator characterized by the above.