JPH02229902A - Pneumatic driving unit - Google Patents

Abstract

PURPOSE:To speed up a positioning work by setting output signals from both a fluid power detecting unit and a working-state detecting unit as input data in order to estimate an external disturbance acting on a working part and obtaining a command value that is necessary to compensate the external disturbing force together with outputting the value to a control valve group. CONSTITUTION:A disturbing force compensating part 15 takes in the signal from a position sensor 11 and from pressure sensors 12a and 12b and outputs a command value on the opening areas of control valves 10a and 10b, which are necessary to cancel the friction force acting on a piston 2, utilizing a friction-force-value estimated by an external disturbing force estimating part. Command value compensating parts 16a and 16b input a sum of command values from a control part 14 and from the compensating part 15 to the control parts 10a and 10b in order to compensate the command values, based on a prescribed, relational expression. By changing the opening area of the valve part, the control valves 10a and 10b change the rate of inflow/outflow to/from pneumatic chambers 1a and 1b, thereby controlling both the pressures in the pneumatic chambers 1a and 1b and the position of a load 6. With this contrivance, quick and precise control can be achieved.

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, pneumatic drive devices have a high output-to-weight ratio of the operating part, making it possible to make the operating part smaller and lighter, and are inexpensive.Motor power can be easily transmitted from the drive source to the operating part through piping, making it easier to construct systems. It is widely used in industrial fields due to its advantages such as a high degree of freedom.

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

Figure 4 shows an example of a conventional pneumatic drive device. In Fig. 4, 1 is a cylinder having an air chamber, 2 is a piston that can move inside the cylinder 1 while maintaining airtightness;
la, lb are air chambers divided by piston 2, 3
Control valves a and 3b have the function of fully opening or closing the valve portions in order to allow air to flow in and out of the air chambers 1a and Ib, respectively; 4 is a compressed air source; 5 connects the operating portion 2 and the load 6; Rondo 7 is a position regulating pin provided on the load 6,
8a and 8b are position regulating bins fixed on a base (not shown), and 9 is a control unit 211 that receives an operation command and provides a command value to the control valves 3a and 3b.

The operation of the conventional pneumatic drive device configured as described above will be explained below.

First, consider the case where the load 6 is operated from the pin 8a toward the pin 8b. The control valves 3a and 3b are three-boat valves, and each boat is connected to a compressed air source 4, an air chamber 1a or ib, and an atmosphere open to the atmosphere. The air flow path inside the valve includes compressed air a4, air chamber 1a or lb, and air chamber 1a.
Alternatively, there are two systems from lb to open to atmosphere, and each flow path has a valve section. The valve portions of each flow path within one control valve do not open at the same time, and when one is open, the other is closed. Based on the input operation command, the control unit 9 fully opens the valve part of the control valve 3a in the flow path from the compressed air source 4 to the air chamber 1a, and at the same time opens the valve part of the control valve 3b in the flow path from the air chamber 1b to the atmosphere open. Fully open a certain valve. As a result, high pressure air flows into the air chamber 1a from the compressed air source 4 and
The internal pressure of the air chamber 1b increases, and conversely, the internal pressure of the air chamber 1b becomes atmospheric pressure, so the differential pressure between the air chambers 1a and 1b is applied to the piston 2, which becomes a driving force and connects the piston 2 with the gasket 5. The load 6 that is being moved moves from the pin 8a toward the pin 8b. Finally, the position of the bin 7 provided on the load 6 is regulated by the bin 8b, and the load 6 stops at that position. Conversely, when operating from the bottle 8b to the pin 8a, the commands given to the control valves 3a and 3b may be reversed, and at this time the load 6 is stopped because the position of the pin 7 is regulated by the pin 8a. In this way, the control valve 3a
, fully open 3b. The positioning operation of the load 6 can be realized simply by fully closing it.

Next, another example of the conventional pneumatic drive device will be described.

FIG. 5 shows another example of a conventional pneumatic drive device. In Fig. 5, l 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 the piston 2, 4 is a compressed air source, 5 is a loft that connects the operating part 2 and the load 6, and 10a and 10b are air chambers, respectively. A control valve having a function of changing the opening area of the valve portion according to a command value in order to cause air to flow in and out of the chambers 1a and 1b, 1l is a position sensor that detects the position of the load 6, and 12a and 12b are respectively Pressure sensor 13 that detects the internal pressure of the air chambers 1a and lb
1 is a control unit which takes in signals from the position sensors lm pressure sensors 12a and 12b and target position commands and provides command values to the control valves 10a and lOb. Here, the control valves 10a and 10b are the same as the control valves 3a and 3b in FIG.
It has two boats and two flow paths, and each flow path is not opened at the same time, but the valve parts provided in each flow path are control valves 3a,
3b, it has a function of changing the opening area according to a command value.

The operation of the conventional pneumatic drive device configured as described above will be explained below.

First, FIG. 6 shows a detailed internal explanatory diagram of the control section 13 in FIG. 5. In FIG. 6, 13a is an integrator, 13b is a differentiator, and 13c-13f are amplifiers. Amplifier 13c.
The outputs of 13d are feedback components of the position deviation of the operating part with respect to the target position, the speed of the operating part, and the pressure deviation with respect to the equilibrium pressure of the air chambers 1a and 1b. It constitutes a state feedback system '<H system of the pneumatic drive system. Further, the outputs of the amplifiers 13e and 13f are amplified and outputted integral values of the positional deviation. Therefore, the influence of the compressibility of air on the positioning operation of the pneumatic drive device is suppressed by the state feedback control, and the disturbance force applied to the piston 2 due to the friction between the cylinder 1 and the piston 2 is suppressed from the positioning operation by the integral control of the position deviation. A control system is configured to suppress the influence, and the resulting adder 13
The output of control valve 10a. By changing the opening angle of 10b, high-precision positioning operation at any position of the operating part in the pneumatic drive device is realized.

(For example, Noritsugu et al., ゜''Optimal control of pneumatic servo system considering operation delay of electro-pneumatic control valve++, Proceedings of the Institute of ML Instrumentation and Automatic Control, Vol. 24, No. 5, May 1988, p. 58 ).

Problems to be Solved by the Invention However, the above configuration causes the following problems. In other words, in the first conventional example, operations such as positioning are realized with a relatively simple configuration, but since positioning is performed by mechanical position regulation, high-speed positioning is possible; Problems arise in that only positioning operations between points can be realized, the target position cannot be easily changed, and positioning at many points is difficult.

In addition, in the second conventional example, the influence of air compressibility on positioning is suppressed by applying state feedback control using information from position sensors, pressure sensors, etc.
In addition, since the positioning operation is performed while integrating the positional deviation and suppressing the influence of frictional force, which is a disturbance force applied to the piston, positioning operation at any position can be easily achieved, and therefore the target position can be changed. It is also easy to position multiple points. However, in order to suppress the influence of frictional force, an integrator is used to integrate the positional deviation, so the integration operation takes a considerable amount of time.Especially in pneumatic drive systems, the frictional force is large, so as a result, it takes a long time to complete positioning. A problem arises in that it takes a long time.

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

Means for Solving the Problems F In order to solve the problems, the pneumatic drive device M of the present invention includes:
A pneumatic actuator having an air chamber and an operating section movable within the air chamber while maintaining airtightness, and causing air to flow into or out of each of the air chamber groups divided by the operating section according to a command value. A control valve group capable of
a fluid force detection unit that detects fluid force applied to the operating unit;
an operating state detecting section for detecting an operating state of the operating section; output signals of the operating state detecting section and the fluid force detecting section; and a target operating state for the operating section to move according to the target operating state. an operation control unit that outputs a necessary command value to the control valve group; and an output signal of the fluid force detection device and an output signal of the operation state detection device to estimate a disturbance force applied to the operation unit; and a disturbance force compensator that calculates a first order value necessary for compensating the disturbance force using the estimated disturbance force and outputs it to the control valve group.

Operation The present invention suppresses the influence of air compressibility on positioning by applying state feedback control using information from position sensors, pressure sensors, etc. with the above-described configuration, and reduces frictional force, which is a disturbance force applied to the piston. By estimating and applying a compensation input that directly cancels out the frictional force using the estimated value, it is possible to quickly suppress the influence of the frictional force, and therefore to perform operations such as positioning to an arbitrary target position at high speed. It can be easily realized 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 diagram showing the configuration of a pneumatic drive device in an embodiment of the present invention. In Fig. 1, l is a cylinder having an air chamber, 2 is a piston that can move inside the cylinder l while maintaining airtightness, and l is a cylinder that has an air chamber.
a and lb are air chambers divided by the piston 2, 4 is a compressed air source, 5 is a rod connecting the operating part 2 and the load 6,
lQa and 10b allow air to flow into the air chambers 1a and lb, respectively. A control valve having a function of changing the opening area of the valve portion according to a command value to allow the flow to flow out, 1l is a position sensor for detecting the position of the load 6, and 12a and 12b are for detecting the internal pressure of the air chambers 1a and 1b, respectively. 14 is a pressure sensor for detecting the position sensor 11, a control section that takes in signals from the pressure sensors 12a and 12b and a target position command, and provides command values to the control valves 10a and fob; 15 is a control section for the position sensor 11. Pressure sensor 12
a disturbance force compensator that takes in the signals of signals a and 12b, estimates the frictional force that is the disturbance force applied to the piston 2, and outputs a compensation input that directly cancels out the frictional force using the estimation;
Reference numerals 16a and 16b are command value compensators that correct inputs from the control unit l4 and the disturbance force compensator l5 to the control valves 10a and 10b.

The pneumatic drive device configured as described above is shown in Fig. 1 below. Figure 2. The operation will be explained using FIG.

First, FIG. 2 is a detailed explanatory diagram showing the internal configuration of the control section 14 in FIG. 1. In FIG. 2, 14a is a differentiator;
14b and 14c are amplifiers.

Amplifier l4b. The output of l4C is the position deviation of the operating part from the target position, the speed of the operating part, and the air chamber +a, lb.
These components constitute a state feedbank control system of the pneumatic drive system including the cylinder 1, the operating section 2, the rod 5, and the load 6. Therefore, the compressibility of the air does not affect the positioning operation by lever state feedback control, suppressing the influence and realizing the positioning operation at any position of the operating section.

Next, FIG. 3 is a detailed explanatory diagram of the disturbance force compensation section 15 in FIG. 1. In FIG. 3, 15a is a disturbance force estimator that estimates the frictional force etc. applied to the piston 2, and its internal configuration will be explained below. First, the pressure in the air chambers 1a, lb is set to pl. p2, the mass of the piston 2, rod 5, and load 6 as a whole is M, and the pressure receiving area of the air chamber la side of the piston 2 is A.
1. If the pressure receiving area on the air chamber lb side is A2, the piston position when the center position of the piston 2 is taken as the origin is X, and the frictional force applied to the piston 2 is T, then Mx=A (p+
-P2) The relationship 10T holds true. Here, assuming that the frictional force T in the above equation is constant, the state variable vector X.

(x, x, T,), the input variable U is (p.-p2), and the output variable y is X, then the state equation and output equation for the system in the above equation are x 6 = A6 x 6 + b 8u
-(1) y=cθXe {and then ce=(1 0 0). (Since the system from the pressure pm, P2 related to the movement of the piston 2 shown in υ2 to the position 1x of the piston 2 is a linear system, an observer (state estimation H) having the following structure can be configured.

That is, X, wA, Xe+b. u-}-k6 (y)')
......(2) T,=c,xe where c,= (0,0.1). Here x8. y, T, are respectively x8,>I
, T, and k8 is the gain hector of the observer. By appropriately determining this gain vector, X and XI3 will quickly match, and therefore the frictional force T included in X8 can be estimated. The disturbance force estimator 15a calculates (2
) is realized using an electric circuit or software. Next, 1 5 b, 1 5 c are the control valves 1 0 a, 1 necessary to cancel the frictional force actually applied to the piston 2 using the value of the frictional force estimated in 5 a.
This is a disturbance compensator that outputs the command value of the aperture area to 0b, and outputs from 15a and 15b are used as slab and s2.
9k, S+eb = kikl ・T, /2s. 、．
=-k. hx − 'r, /2 −・−(
4). Here, k9kl + k9ht is Sllb + szg, which is the input to the control valves 10a and 10b.
This is the total disturbance compensation gain of the pneumatic drive device from h to X, which is the output of the position sensor 1l.

In this way, the disturbance force compensator l5 accurately estimates the frictional force applied to the piston 2, and directly outputs the command value necessary to cancel the influence of the frictional force to each control valve. ! The influence of J force on positioning accuracy can be suppressed at high speed, and high-speed and highly accurate positioning operation can be realized.

Next, the command value compensators 16a and 16b receive signals from the control valve 10a and the disturbance force compensator 15 from the control unit 14 and the disturbance force compensator 15, respectively. The total command value to 10b is input, and the command value is corrected based on the following relational expression. Control valve 10a from control unit 14 and disturbance force compensation unit l5,
The total of the command values to 10b is Sll' + 32
,, from the command value compensator 16a16b to the control valves 10a, 10
If the output to b is 81, S2, then α1, α2 are P, /P0, where P3 is the pressure of the compressed air source 4, and P0 is the equilibrium pressure in the steady state in the air chambers 1a, lb. be. The control valves 10a and 10b control the pressure in the air chambers 1a and 1b and the position of the load 6 by changing the inflow and outflow flow rates to the air chambers 1a and 1b by changing the opening area of the valve portion. However, the relationship between this opening area and flow rate is different for inflow (S, ≧0) and outflow (S
, < 0) and differ as follows. That is, the control valve 10a
Considering the case, and assuming that the flow rate is G, (GI≧0 in the case of inflow, G, <0 in the case of outflow), the relationship 2 is expressed as follows (7). Here, K0 is a constant determined by the air temperature and air characteristic values. Since P, #P0, (5
), (6) By making the corrections shown in (2), it is possible to make the characteristics uniform between the outflow and inflow cases, thereby realizing faster and more accurate control. As described above, according to this embodiment, the influence of friction force, which is a disturbance force applied to the operating part, is suppressed at high speed by the disturbance force compensator, and the influence of the compressibility of air is suppressed by the operation control part. By equalizing the air inflow and outflow characteristics using the command value compensator, operations such as positioning to an arbitrary target position can be easily achieved at high speed and with high precision.

In this embodiment, the disturbance force estimator in the disturbance force compensator is configured with the same-dimensional observer shown in equation (2), but it is not necessarily limited to this configuration. For example, other state observers such as a minimum-dimensional observer It may be configured as follows. Also, the command value compensation section is (5). α1 and α2 in equation (6) are constants P. /P, but this is a simple method and is not necessarily limited to this correction method. For example, α1. in equations (5) and (6). α2 is αr −P * / P1...
...(8) It may be given as a variable like α2==p, /p2. In this case, it is possible to achieve more uniform flow characteristics in the control valve, it is possible to achieve more uniform flow characteristics in the control valve, and even higher speed and higher precision can be achieved.

Effects of the Invention As described above, the pneumatic drive device of the present invention includes a pneumatic actuator having an air chamber and an operating section that is movable within the air chamber while maintaining airtightness, and a group of air chambers divided by the operating section. a control valve group capable of causing air to flow in or out according to a command value, a fluid force detection section that detects fluid force applied to the operating section, and an operating state detection section that detects the operating state of the operating section. output signals of the operating state detecting section and the fluid force detecting section, and a target operating state to output a command value necessary for the operating section to move according to the target operating state to the control valve group. an operation control unit that estimates a disturbance force applied to the operation unit by inputting an output signal of the fluid detection device and an output signal of the operation state detection device, and calculates a command value necessary for compensating for the disturbance force. By providing a disturbance force compensator that calculates using the estimated disturbance force and outputs it to the control valve group, arbitrary operations such as positioning of the pneumatic drive device can be easily achieved at high speed and with high precision. It has the effect of being able to

[Brief explanation of the drawing]

FIG. 1 is an overall view of a pneumatic drive device according to an embodiment of the present invention, FIG. 2 is a detailed view of an operation control section in the same pneumatic drive device, and FIG. 3 is a detailed view of a disturbance force compensator in the same pneumatic drive device. FIG. 4 is an overall view of a conventional pneumatic drive device, FIG. 5 is an overall view of another conventional pneumatic drive device, and FIG. 6 is a detailed explanatory diagram of an operation control section in the conventional pneumatic drive device. l...Pneumatic cylinder, 2...Piston, 10a10b...Control valve, 11...
- Position sensor, 12a. 12b...Pressure sensor, 14...Control unit, l5...Disturbance force compensation unit. Name of agent: Patent attorney Shigetaka Awano

Claims (7)

[Claims] (1) A pneumatic actuator that has an air chamber and an operating section that can move within the air chamber while maintaining airtightness, and air flows into or out of each of the air chamber groups divided by the operating section according to a command value. a group of control valves that can be operated, a fluid force detection section that detects fluid force applied to the operating section, an operating state detection section that detects the operating state of the operating section, the operating state detection section and the fluid force detection section. an operation control section that outputs a command value necessary for the operation section to move according to the target operation state to the control valve group by inputting an output signal of the section and a target operation state; a disturbance force compensator that outputs a command value necessary for compensation to the control valve group, and the disturbance force compensator receives an output signal of the fluid force detection device and an output signal of the operating state detection device as input. A pneumatic drive device, characterized in that a disturbance force applied to the operating section is estimated, a command value necessary to compensate for the disturbance force is determined using the estimated disturbance force, and is output to the control valve group. (2) The disturbance force compensator comprises a dynamic characteristic model representing the relationship between the fluid force applied to the operating section of the pneumatic drive device and the operating state of the operating section, and a dynamic characteristic model of the disturbance force. The pneumatic drive device according to claim 1, wherein the disturbance is estimated by a device. (3) The pneumatic drive device according to claim 1, wherein the disturbance force compensator obtains a command value necessary for compensating the disturbance force by multiplying the estimated disturbance force by a coefficient. (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.
pneumatic drive device described in ). (5) The pneumatic drive device according to claim (1), wherein the operating state detection section is constituted by any one of means for detecting position, velocity, and acceleration, or a combination thereof. (6) Input a command value to the control valve group, determine whether air flows into or out of the air chamber group based on the command value, and determine whether air flows in or out of the air chamber group. The pneumatic drive device according to claim 1, further comprising a command value correction section that corrects the command value and outputs the command value to the control valve group. (7) The pneumatic drive device according to claim (6), wherein the command value correction section is constituted by a correction means that multiplies the command value by a certain constant coefficient.