JPH044301A - Air pressure driving device - Google Patents

Abstract

PURPOSE:To carry out an operation such as positioning in a high speed and a high accuracy by making a time constant in which driving forces vary with driving signals smaller than a time constant in which opening quantities vary with changes in driving forces applied to first and second control valves. CONSTITUTION:Valve control units 10a, 11a operate opening degree errors from opening degrees of control valves 3a, 3b detected by opening degree sensors 12a, 12b and opening degree commanding signals for the control valves 3a, 3b coming from a control unit 9, use only the maximum value of the driving forces in positive and negative directions even if there are hysteresises on characters of driving forces applied to the control valves 3a, 3b, and suppress influences thereof. Next, driving forces are detected by driving signal correcting units 10b, 11b, driving signals are operated and output on using differences between the driving forces and outputs of the valve control units 10a, 11a and differential values of the differences, and a time constant in which driving forces vary due to driving signals to the control valves 3a, 3b is made smaller than a time constant in which the opening degrees vary due to driving force changes. It is possible thereby that opening degrees of control valves coincide with commanded values in high speed without chattering, and positioning or the like is performed in high speed and with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a pneumatic drive device that operates using a compressed air source as a drive source.

Conventional technology In recent years, the pneumatic drive device ζ has a high output/weight ratio of the operating part, which allows the operating part to be made smaller and lighter.4 It is inexpensive and affordable.Power can be easily transmitted from the drive source to the operating part through piping, which is useful when constructing a system. It is widely used in industrial fields, taking advantage of its advantages such as a high degree of freedom. In industry, mainly production and
Transfer of parts, etc. in an assembly system Length of force used for assembly Until now, positioning methods using mechanical position regulating means (for example, positioning pins, etc.) have been used, and positioning can only be achieved between two fixed points. Production/
It is difficult to adapt to flexible assembly, so we developed a pneumatic drive device that realizes high-speed and high-precision positioning at any position by controlling the pressure in the air chamber without using mechanical position regulating means. This method has been proposed by the inventor (for example, see Japanese Patent Application No. 1-50322).

An example of the above-mentioned pneumatic drive device will be described below with reference to the drawings.

FIG. 3 shows an example of this pneumatic drive device.

In Fig. 3, 1 is a cylinder having an air chamber, 2 is a piston that can move inside the cylinder 1 while maintaining airtightness;
la and lb are air chambers divided by piston 2 4
5 is a compressed air claw; 5 is a rod connecting the piston 2 and the load 6; 3a and 3b are controls that have the function of changing the opening area of the valve portion in accordance with a command value in order to allow air to flow into and out of the air chambers 1a and 1b, respectively; 7 is a position sensor that detects the position of the load 6; 8a and 8b are pressure sensors that detect the internal pressure of the air chambers 1a and 1b, respectively; 9 is a signal from the position sensor 7, pressure sensors 8a and 8b, and a target position signal The control valves 12a and 12b output the opening amount command signal for the control valves 3a and 3b.
, an opening amount sensor that detects the opening amount of 3b, 13, 1
4 is a control valve 3a from the control section.

3b opening amount command signal and opening amount sensors 12a, 12b
This is a valve control drive unit that inputs an opening amount signal and outputs a drive signal to the control valves 3a and 3b.

The operation of the pneumatic drive device configured as described above will be explained below using FIG. 3@FIG. 4.

FIG. 4 is a detailed explanatory diagram showing the internal configuration of the control section 9 in FIG. 3. In FIG. 4, 9a is a position control unit which controls the control valve 3a using the input target position signal xd, the piston position X1 detected by the position sensor 7, and the pressures p1 and p2 in the air chamber 1a11b detected by the pressure sensors 8a and 8b. , opening amount command signals sal, sb to 3b
Find l using the following formula, 5al= (kl(xcl-
x)-to 2・x)/2-to 3(pi-po)
(1) Here 1, k2. 3 is a state feedback gain determined based on the dynamic characteristic equation of the pneumatic drive system including the cylinder 1, piston 2, rod 5, load 6, and control valves 3a and 3b, and pO is the equilibrium pressure.

Feedback control based on equation (1) constitutes a state feedback control system for the pneumatic drive system, which suppresses the influence of air compressibility on positioning operation and enables positioning operation at any position of the operating part. It has been realized.

Next, the disturbance force compensator 9b in FIG. 4 will be explained. The disturbance force compensator 9b first detects the detected air chambers 1a and 1b.
A disturbance estimation observer using a dynamic characteristic model regarding the motion of the piston 2 from the pressure difference to the position of the load 6 and a dynamic characteristic model of the frictional force that assumes that the frictional force applied to the piston 2 is constant. By feeding back the difference between the output of the position sensor 7 and the estimated position of the piston 2 within the disturbance estimation observer, the frictional force is estimated at high speed. Next, the estimated frictional force value is used to send opening amount command signals sad and sb to the control valves 3a and 3b necessary to cancel the frictional force actually applied to the piston 2.
2, thereby making it possible to compensate for the frictional force applied to the piston 2 at high speed.

Further, in FIG. 4, reference numeral 90 is a drive signal addition section, which includes control valves 3a, 3 from the position control section 9a and the disturbance force compensation section 9b.
Manually input the opening amount command signal to the control valve 3a13b and set the drive signals sar and sbr to the control valve 3a13b as follows: s ar= s a1+ s
a2 (2) s br= s
It is determined by bl+s b2 and is output as an opening amount command signal to the control valves 3a and 3b.

Next, the valve control drive units 13 and 14 in FIG.
The opening amount command signal and the actual opening amount signal are input to the control valves 3a and 3b from the control valves 3a and 3b, and the difference and the integral 4L of the difference are input to the control valves 3a and 3b based on linear feedback using the differential value of the opening amount signal. The opening amount of the control valves 3a and 3b can be controlled to a desired value.

These operations constitute a control system that quickly compensates for the friction applied to the piston 2 while suppressing the influence of air compressibility on the positioning operation of the pneumatic drive device through state feedback control. Achieves high-speed, high-precision positioning at any position of the operating part.

Problems to be Solved by the Invention However, the above configuration causes the following problems. In other words, if the control valve that actually compensates for air compressibility and frictional force, which is a disturbance force, has nonlinearity such as a dead zone or hysteresis, the actual opening amount may not match the opening amount command value. Compressibility and frictional forces are not completely compensated because it takes a considerable amount of time to match (
Otherwise, it takes time for compensation to be made, resulting in a problem that the positioning speed and positioning accuracy are reduced.

In view of the above-mentioned problems, the present invention provides a pneumatic drive device that realizes operations such as positioning to an arbitrary target position at high speed and with high precision.

Means for Solving the Problems In order to solve the above problems, a pneumatic drive device ζ of the present invention is provided.
First, the pressure changes as air flows in or out.
a second air chamber, and a movable operating section that forms a boundary between the first and second air chambers and is driven by the pressure difference between the first and second air chambers while maintaining airtightness. a pneumatic actuator having a pneumatic actuator, first and second fluid force detection sections that detect the fluid forces of the first and second air chambers, an operating state detection section that detects the operating state of the operating section, and the first and second control valves that can allow air to flow in or out of the first and second air chambers by changing their opening amounts in accordance with input signals; and the first and second control valves. first and second opening amount detectors that detect the opening amount of each of the valves, and Q-10- an output signal of the operating state detector and an output signal of the first and second fluid force detectors; and a target operating state signal, and calculate opening amounts of the first and second control valves, which are control amounts necessary for the operating section to move according to the target state signal, and perform the first and second control. An operation control section that outputs the opening amount command signal that drives the valve, an opening amount command signal to the first and second control valves, and output signals of the first and second opening amount detection sections are manually controlled. and calculating drive signals necessary for the output signals of the first and second opening amount detection sections to match opening amount command signals to the first and second control valves, respectively; and first and second valve control drive units that output an output to the second control valve, and the first and second valve control drive units output an opening amount command signal to the first and second control valves manually. and the respective differences between the output signals of the first and second aperture amount detection sections, and the respective linear combination sums thereof up to the nth-order differential value (n: a positive integer). The sign of each of the linear combination sums. a valve control section that switches and outputs a constant drive signal in the direction of increasing the opening amount and a constant driving signal in the direction of decreasing the opening amount in accordance with the first and second opening amounts. The time constant at which the opening amount changes due to a change in the driving force applied to the valve element of the second control valve is determined by the time constant at which the driving force applied to the valve element of the first and second control valves changes due to the output drive signal. and a drive signal correction section that corrects the drive signal so that it becomes smaller and outputs it to the first and second control valves.

Operation The present invention increases the opening amount of the control valve with the above-described configuration.
By switching a constant driving force in the decreasing direction at high speed, the opening amount can be controlled at high speed and with high precision without being affected by nonlinearity such as the dead zone and hysteresis of the control valve. It is possible to perform operations such as positioning to a target position at high speed and with high precision.

EXAMPLE Hereinafter, a pneumatic drive device according to an example of the present invention will be described with reference to the drawings.

FIG. 1 is an overall view showing the configuration of a pneumatic drive device in an embodiment of the present invention. In Fig. 1, 1 is a cylinder with an air chamber; 2 is a piston that can move inside the cylinder 1 while maintaining airtightness; a, lb are air chambers 4 divided by the piston 2; compressed air a; 5 is the piston 2 and the load Rods 3a and 3b connect the air chambers 1a and 1b, respectively, and control valves have the function of changing the opening area of the valve portion according to a command value in order to allow air to flow in and out of the air chambers 1a and 1b, respectively.7 is a control valve that controls the position of the load 6. position sensor to detect, 8
a and 8b are pressure sensors that detect the internal pressure of the air chambers 1a and lb, respectively; 9 is a position sensor 7; a pressure sensor 8a;
Take in the signal of 8b and the target position signal Control valve 3a,
control ability to output the opening amount command signal 12a of 3b;
12b is an opening amount sensor that detects the opening amount of the control valves 3a and 3b; 10 and 11 are control valves 3a and 3b from the control section;
These are first and second valve control drive units that manually input the opening amount command signal to the valves and the opening amount signals of the opening amount sensors 12a and 12b, and output drive signals to the control valves 3a and 3b.

The operation of the pneumatic drive device configured as described above will be explained below using FIG. 1@FIG. 2.

First, FIG. 2 is a detailed explanatory diagram showing the internal configuration of the control section 9 in FIG. 1. As shown in FIG. In FIG. 2, 9a is a position control unit that uses the input target position signal xd, the piston position X detected by the position sensor 7, and the pressures p1 and p2 in the air chambers 1a and lb detected by the pressure sensors 8a and 8b. Opening amount command signals sal and sb to control valves 3a and 3b
Find l using the following formula.

5a1= (k 1 (Xd-X) -k2・X
) /2-k3 (pi-pO)
(3) sbl=-(kl (xd-x) -2・
x)/2-k3 (p 1-po) where 1, k2. 3 is cylinder 1, piston 2,
It is the state feedback gain determined based on the dynamic characteristic equation of the pneumatic drive system including the rod 5, the load 6, and the control valves 3a and 3b, and pO is the equilibrium pressure. (3)
Feedback control based on the equation constitutes a state feedback control system for the pneumatic drive system, which suppresses the influence of air compressibility on positioning operation and realizes positioning operation at any position of the operating part. There is.

Next, the disturbance force compensator 9b in FIG. 2 will be explained. The disturbance force compensator 9b first uses the detected pressure difference between the air chambers 1a and lb as human power, and creates a dynamic characteristic model for the movement of the piston 2 from the pressure difference to the position of the load 6, and assumes that the frictional force applied to the piston 2 is constant. The frictional force is estimated at high speed by feeding back the difference between the output of the position sensor 7 and the estimated position of the piston 2 within the disturbance estimation observer using the assumed dynamic characteristic model of the frictional force. Next, using the estimated frictional force value, the opening amount command signals sad and s to the control valves 3a and 3b necessary to cancel the frictional force actually applied to the piston 2 are sent.
b2, thereby making it possible to compensate for the frictional force applied to the piston 2 at high speed.

Further, in FIG. 2, 90 is a drive signal adder, and control valves 3a, 3b from the position controller 9a and the disturbance force compensator 9b.
Input the opening amount command signal to the control valve 3a13b, and input the drive signals sar and sbr to the control valve 3a13b as sar=s al+s
a2 (4) s br= s b
It is determined by l+s b2 and is output as an opening amount command signal to the control valves 3a and 3b.

Next, the first and second valve control drive sections 10 and 1 in FIG.
1 inputs an opening amount command signal and an actual opening amount signal from the control unit 9 to the control valves 3a and 3b, and outputs a drive signal to the control valves 3a and 3b based on the difference.The details will be explained below. This will be explained using FIG.

10a and lla in FIG. 1 are valve control parts, and the control valve 3a detected by the opening amount sensors 12a and 12b
, 3b opening amounts sa, sb and the control valve 3 from the control section 9
From the aperture command signals sar and sbr to a and 3b, the aperture error is calculated, e a = s ar - s a
(5) Calculate e b = s br - s b . Next, the time differentials ea and eb of this are obtained, and their linear combination coefficient Ca-ea+ha1 ea cb=eb+hb-eb is obtained. Here, ha and hb are positive constants that determine the responsiveness of the opening amount to the opening amount command value of the control valve. Here, the valve control units 10a and 10b output drive signals uar and ubr according to the signs of ca and cb. Here, fal and fbl are the maximum driving force to the valve body in the direction of increasing the opening amount of the control valves 3a and 3b (ifaλ fb2 is the driving force to the valve body in the direction of decreasing the opening amount of the control valves 3a and 3b. is the maximum value of the control valves 3a and 3b, α and β are the maximum values of the control valves 3a and 3b.
This is a coefficient that takes a value of either 1 or -1 determined by the conversion characteristics between the drive signal applied to the valve body and the drive force applied thereby to the valve body. Thereby, even if there is hysteresis in the characteristics of the driving force applied to the valve bodies of the control valves 3a, 3b, the influence can be suppressed because only the maximum value of the driving force in the positive and negative directions is used.

Next, 10b and llb are drive signal correction units that correct the drive signals that are the output signals of the valve control unit, and convert the drive forces ua and ub actually applied to the valve body into the drive signals that are the output signals of 10b and 11b. The valve control units 10a, 10 are detected using
Using the difference between the outputs uar and ubr of b, and the differential value of the difference,
Drive signals uac and ubc as uac=kual-eua
-kua2・ua (8) ubc=kub1
- eub - kub2 - lb However, eua = uar - ua eub = ubr - ub is calculated and output. Here, kual, kua2゜kubl, kub2 is a feedback gain, which is a time constant force length at which the driving force applied to the valve body changes depending on the drive signal to the control valves 3a, 3b. The opening amount is determined to be smaller than the changing time constant. As a result, the valve control section 10a, ll
The opening amount of the control valves 3a, 3b can be made to match the opening amount command value at high speed without vibrationally changing (juttering) the opening amount of the control valves 3a, 3b due to the discontinuous drive signal outputted by the switch.

As described above, according to this embodiment, the valve control drive section
The actual opening amount of the control valves 3a, 3b is set to the opening amount command value that suppresses the influence of the frictional force, which is a disturbance force applied to the operating part, and the compressibility of air, which is output from the control unit.
Even if there is non-linearity such as hysteresis in the characteristics of the driving force applied to the valve body b, it can be matched quickly and accurately, and therefore operations such as positioning at an arbitrary target position can be performed at high speed and with high precision. can.

In this embodiment, the internal configuration of the disturbance force compensator is configured using a disturbance force estimation/compensation method (it is not necessarily limited to this configuration; for example, a configuration using a position deviation integral method may be used. In the section, the configuration is based on a proportional/differential system, but the configuration is not necessarily limited to this, and a configuration that combines relative differentiation, integration, etc. may also be used.

Effects of the Invention As described above, the pneumatic drive device method of the present invention has first and second air chambers into which air flows in or out and whose pressure changes;
a pneumatic actuator forming a boundary between the first and second air chambers and having a movable operating section driven by a pressure difference between the first air chamber and the second air chamber while maintaining airtightness; 1. first and second fluid force detection sections that detect the fluid force of each of the second air chambers, an operating state detection section that detects the operating state of the operating section, and the first and second air chambers. A first chamber that allows air to flow in or out by changing the opening amount depending on the input signal to each chamber.
, a second control valve, and first and second opening amount detection units that detect the opening amount of each of the first and second control valves;
Control necessary for manually controlling the output signal of the operating state detection section, the output signal of the first and second fluid force detection sections, and the target operating state signal so that the operating section moves in accordance with the target state signal. an operation control unit that calculates opening amounts of the first and second control valves and outputs an opening amount command signal that drives the first and second control valves; The opening amount command signal to the valve and the output signals of the first and second opening amount detection sections are respectively inputted, and the output signals of the first and second opening amount detection sections are respectively input to the first and second opening amount detection sections. and first and second valve control drive units that calculate a drive signal necessary to match the opening amount command signal to the control valve and output it to the first and second control valves, respectively. , a second valve control drive section calculates the difference between the manually-powered opening amount command signal to the first and second control valves and the output signals of the first and second opening amount detection sections, and the n-th order differential thereof. Find each linear combination sum up to a value (n: a positive integer). Depending on the sign of each linear combination sum, a constant drive signal in the direction of increasing the aperture amount and a constant drive signal in the direction of decreasing the aperture amount. The control valve is equipped with a valve control unit that switches between and outputs a constant drive signal, and has a time constant in which the opening amount changes due to a change in the driving force applied to the valve bodies of the first and second control valves. Correcting the drive signal so that a time constant for changing the drive force applied to the valve bodies of the first and second control valves by the output drive signal becomes smaller, and outputting the corrected drive signal to the first and second control valves. By including the drive signal correction section, operations such as positioning to an arbitrary target position can be realized at high speed and with high precision.

[Brief explanation of drawings]

Figure 1 shows the entire pneumatic drive device according to the embodiment of the present invention. Figure 2 is a detailed view of the control section of the same pneumatic drive device. Figure 3 shows the entire pneumatic drive device proposed earlier. Figure 4 shows the same pneumatic drive device. FIG. 3 is a detailed explanatory diagram of a control section in the drive device. 1. ・Pneumatic cylinder 2...Piston, 3a, 3
b... Control valve, 7... Position sensor, 8a, 8b.
...Pressure sensor 9...Control section 10, 11...Valve control drive section 12a, 12b...Opening amount detection section

Claims (5)

[Claims] (1) The first stage where air flows in or out and the pressure changes.
, a second air chamber forms a boundary between the first and second air chambers, and is movable by being driven by the pressure difference between the first and second air chambers while maintaining airtightness. a pneumatic actuator having a pneumatic actuator, and first and second fluid force detection units that detect the fluid forces of the first and second air chambers, respectively;
an operating state detection unit that detects the operating state of the operating unit; and a first air chamber that allows air to flow in or out by changing the opening amount in accordance with an input signal to each of the first and second air chambers. , a second control valve, and the first and second control valves.
a first and a second control valve for detecting the opening amount of each of the control valves;
an opening amount detection section, an output signal of the operation state detection section, an output signal of the first and second fluid force detection sections, and a target operation state signal are input, and the operation section moves according to the target state signal. an operation control unit that calculates the opening amount of the first and second control valves, which is a control amount necessary for the operation, and outputs the opening amount command signal that drives the first and second control valves; , an opening amount command signal to the second control valve and the first and second control valves.
The output signals of the aperture amount detectors are respectively inputted, and the first
, the output signal of the second aperture detection section is the first,
It includes first and second valve control drive units that calculate drive signals necessary to match the opening amount command signal to the second control valve and output them to the first and second control valves, respectively. The first and second valve control drive sections detect the difference between the input opening amount command signals to the first and second control valves and the output signals of the first and second opening amount detection sections. and the respective linear combination sums up to their nth derivatives (n: positive integer), and calculate a constant drive signal and the aperture amount in the direction of increasing the aperture amount according to the sign of each of the linear combination sums. The valve controller is equipped with a valve control unit that outputs a constant drive signal in a direction that reduces the amount of the valve, and the opening amount changes according to a change in the driving force applied to the valve bodies of the first and second control valves. The drive signal is corrected so that the time constant at which the drive force applied to the valve bodies of the first and second control valves changes due to the output drive signal is smaller than the time constant. A pneumatic drive device comprising: a drive signal correction section that outputs a drive signal to a control valve. (2) The constant drive signal in the direction of increasing the opening amount of the first and second valve control drive units is the maximum driving force applied to the valve body in the direction of increasing the opening amount of the first and second control valves. The constant drive signal in the direction of decreasing the opening amount is a driving signal corresponding to the maximum driving force applied to the valve body in the direction of decreasing the opening amount of the first and second control valves. The pneumatic drive device according to claim 1, characterized in that: (3) The first and second control valves have driving force characteristics that drive the valve body, such as the maximum driving force applied to the valve body in the direction of increasing the opening amount and the maximum driving force applied to the valve body in the direction of decreasing the opening amount. 3. The pneumatic drive device according to claim 2, wherein the pneumatic drive device has a hysteresis characteristic between. (4) Claim 1, wherein the fluid force detection section is constituted by a pressure detection device group that detects the pressure of each of the air chamber groups.
3. The pneumatic drive device according to 2 or 3. (5) The pneumatic drive device according to claim 1, 2 or 3, wherein the operating state detection section is constituted by any one of means for detecting position, velocity, and acceleration, or a combination thereof.