Pneumatic actuator control device and pneumatic actuator control method

Abstract

To provide a pneumatic actuator control device enabling a piston to be controlled at an arbitrary position while using a pneumatic actuator with a simple configuration.SOLUTION: A pneumatic actuator control device 100 for controlling driving of a pneumatic actuator 30 includes a high pressure tank 110 for supplying compressed air, a supply air adjustment valve for adjusting a flow rate of the compressed air supplied from the high pressure tank 110, a proportional valve control unit 190 for controlling opening / closing of the supply air adjustment valve, a direction switching valve 130 for alternately supplying and exhausting the compressed air whose flow rate is adjusted by the supply air adjustment valve to one chamber and the other chamber separated by the piston 32, which is configured to be able to selectively switch between a first state in which the compressed air can be supplied to the one chamber and exhausted from the other chamber and a second state in which the compressed air can be supplied to the other chamber and exhausted from the one chamber, and a switching valve control unit 180 for switching the first state and the second state of the direction switching valve 130.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a pneumatic actuator control device and a pneumatic actuator control method for use in a railway vehicle. [Background technology]

[0002] In railway vehicles that use air springs to support the car body, a height adjustment device such as that shown in Patent Document 1 is generally used to keep the car body height constant even if the sprung weight changes as passengers get on and off. This height adjustment device may operate in unintended situations, such as when the vehicle is traveling on a curved track, and this operation may cause problems in terms of running safety.

[0003] For example, at a track exit transition curve, the air springs on the outer track side of the leading bogie are stretched due to track planarity, which causes the height adjustment device to perform a venting operation, which tends to reduce the wheel load of the outer track side wheels of the leading bogie.It is desirable to be able to grasp the characteristics of such air spring carbody suspension devices at the design stage and during maintenance, and it is particularly desirable to evaluate the characteristics when the device is attached to the carbody (in its current state), including piping, etc.

[0004] As a method for evaluating the characteristics of an air spring vehicle body suspension system in the above-mentioned standing state, a method of attaching an air pressure cylinder to a height adjustment rod (LV rod) and evaluating the step response by extending and contracting this rod has been proposed in Non-Patent Documents 1 and 2.

[0005] As a related technique, a device in which an electric actuator is attached to the LV rod has also been proposed, as shown in Non-Patent Document 3. This technique makes it possible to continuously control the length of the LV rod.

[0006] Furthermore, prior art related to air pressure control is disclosed in Non-Patent Documents 4-7. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-232716 [Non-Patent Document 1] Hondo, "Transient Characteristic Identification Method for a Height Control Valve Using a Pneumatic Variable-Length Height Adjustment Rod (Proposal of Optimization and Testing Methods Using Domain-Narrowing PSO and Gradient Method)," Transactions of the Japan Society of Mechanical Engineers, Vol. 86, No. 890 (2020), DOI:10.1299 / transjsme.20-00238. [Non-patent document 2] Hondo, "Transient response evaluation of a differential pressure valve for railway vehicles using a pneumatic variable length LV rod," TRANSLOG2022, Paper No. PS2-9, 2022. [Non-patent document 3] Yoshihiro Suda, Wenjun Wang, Yukio Kurosaki, Hisanao Komine, Yoshishi Sato, Takuji Nakai, and Yoshiyuki Shimokawa, "Study on Wheel Load Loss Suppression Control of Air Spring Systems for Railway Vehicles," Transactions of the Japan Society of Mechanical Engineers, Series C, Vol. 71, No. 702 (2005), pp. 94-99. [Non-patent document 4] Tanaka, "Position Control of Servo Cylinder Using Electro-Pneumatic Proportional Control Valve (Characteristics of Position Proportional Control Valve and Its Applications)," Hydraulics and Pneumatics, Vol. 12, No. 4, pp. 277-281, 1981 [Non-patent document 5] Lee, Noritsugu, "Speed ​​Control and Positioning Control of Pneumatic Cylinders Using Robust Pole Placement Theory," Hydraulics and Pneumatics, Vol. 26, No. 1, pp. 88-92, 1995 [Non-patent document 6] Noritsugu, Hanafusa, "Pulse Width Modulation Speed ​​Control of Pneumatic Cylinders - Constant Speed ​​Feed During Low Speed ​​Drive -", Hydraulics and Pneumatics, Vol. 14, No. 7, 1983 [Non-Patent Document 7] Noritsugu and Wada, "Configuration of a PCM-type digital pneumatic servo controlled by a microcomputer," Transactions of the Society of Instrument and Control Engineers, Vol. 23, No. 3, 1987 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the techniques disclosed in Non-Patent Documents 1 and 2, the length of the piston rod of the pneumatic cylinder can only be controlled in two ways: fully extended or fully retracted. Therefore, it is not possible to continuously evaluate the vehicle response to the displacement of the LV rod.

[0009] Furthermore, the technology disclosed in Non-Patent Document 3 has the problem that it is generally difficult for an electric actuator to achieve both force and speed. Therefore, in order to achieve a high speed sufficient for evaluating the step response while receiving a reaction force from the LV lever, it is more advantageous to use a pneumatic cylinder.

[0010] Furthermore, the technology disclosed in Non-Patent Document 4 has the problem that operation may become unstable in the minute flow rate region, and that a control circuit for the proportional valve requires at least two channels.

[0011] Furthermore, in the technology disclosed in Non-Patent Document 5, in the case of a proportional valve whose flow rate characteristics change depending on the pressure difference, the exhaust side valve may not operate as intended, and there are problems in that the control circuit for the proportional valve requires at least two channels, and depending on the valve configuration, four channels may be required.

[0012] Furthermore, the technology disclosed in Non-Patent Document 6 has the advantage that only the operation of the switching valve is required, but has the problem that it requires the use of a special electromagnetic valve with good response.

[0013] Furthermore, the technology disclosed in Non-Patent Document 7 has the advantage that it is only necessary to operate a switching valve, but has the problem that it is necessary to use a large number of switching valves to improve the speed resolution.

[0014] The present invention has been made in consideration of the above circumstances, and has an object to provide a pneumatic actuator control device and a pneumatic actuator control method that are capable of controlling a piston to any position while using a pneumatic actuator and that can have a simple configuration. [Means for solving the problem]

[0015] [1] In order to solve the above-mentioned problems, according to a first aspect of the present invention, there is provided a pneumatic actuator control device for controlling the operation of a pneumatic actuator that changes the length of a height adjustment rod that adjusts the body height of a railway vehicle, the pneumatic actuator having a cylinder, a piston, and a piston rod, the pneumatic actuator control device comprising: a high-pressure tank that supplies compressed air; an air intake adjustment valve that adjusts the flow rate of the compressed air supplied from the high-pressure tank; a proportional valve control unit that controls the opening of the air intake adjustment valve; a directional control valve that alternately supplies and exhausts compressed air, the flow rate of which is adjusted by the air intake adjustment valve, to one chamber and another chamber isolated by a piston in the cylinder, the directional control valve being configured to be selectively switched between a first state in which air can be supplied to one chamber and exhausted from the other chamber, and a second state in which air can be supplied to the other chamber and exhausted from the one chamber; and a directional control valve control unit that switches the first state and the second state of the directional control valve.

[0016] [2] Furthermore, in order to solve the above-mentioned problems, according to a second aspect of the present invention, there is provided a method for controlling the drive of a pneumatic actuator having a cylinder, a piston, and a piston rod, which is a pneumatic actuator that changes the length of a height adjustment rod that adjusts the body height of a railway vehicle, the pneumatic actuator comprising: a high-pressure tank that supplies compressed air; an air intake adjustment valve that adjusts the flow rate of the compressed air supplied from the high-pressure tank; and a directional control valve that alternately supplies and exhausts the compressed air, the flow rate of which is adjusted by the air intake adjustment valve, to one chamber and another chamber isolated by a piston in the cylinder, the directional control valve being configured to be selectively switched between a position where air can be supplied to one chamber and exhausted from the other chamber, and a position where air can be supplied to the other chamber and exhausted from the one chamber, characterized in that the method controls the opening of the air intake adjustment valve to switch the position of the directional control valve. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a pneumatic actuator control device and a pneumatic actuator control method that are capable of controlling a piston to any position while using a pneumatic actuator and that can have a simple configuration. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a diagram showing a schematic side view of the vicinity of a bogie of a railway vehicle on which a pneumatic actuator control device according to an embodiment of the present invention is provided; [Figure 2] 2 is a schematic diagram showing the operation of the automatic height adjusting device in the vehicle shown in FIG. 1. [Figure 3] 1 is a block diagram relating to control of a pneumatic actuator control device according to a first configuration example. [Figure 4] FIG. 10 is a block diagram relating to control of a pneumatic actuator control device according to a second configuration example. [Figure 5] FIG. 10 is a block diagram relating to control of a pneumatic actuator control device according to a third configuration example. [Figure 6] FIG. 10 is a block diagram relating to control of a pneumatic actuator control device according to a fourth configuration example. [Figure 7] FIG. 10 is a block diagram relating to control of a pneumatic actuator control device according to a fifth configuration example. DETAILED DESCRIPTION OF THE INVENTION

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pneumatic actuator control device according to an embodiment of the present invention will now be described with reference to the accompanying drawings.

[0020] [Configuration of the pneumatic actuator control device 100 and the bogie 10 of the railway vehicle 1] FIG. 1 is a diagram showing a schematic side view of the vicinity of a bogie of a railway vehicle on which a pneumatic actuator control device 100 according to an embodiment of the present invention is installed.

[0021] As shown in Fig. 1, a railway vehicle (hereinafter simply referred to as "vehicle") 1 is, for example, a bogie car of a passenger train or the like, which has a pair of bogies 10 at the front and rear of a car body 2. The car body 2 has a compartment portion in which passengers and the like are accommodated.

[0022] The bogie 10 is, for example, a two-axle bogie, and includes a bogie frame 11, a wheel set 12, an axle box 13, an axle box support device 14, an axle spring 15, an axle damper 16, an air spring 17, and the like.

[0023] The bogie frame 11 is a structural member that constitutes the main body of the bogie 10. The bogie frame 11 is configured by connecting a pair of left and right side beams that extend in the longitudinal direction and are spaced apart in the width direction (sleeper direction) by cross beams and end beams that extend along the sleeper direction. Brackets 11a are provided on the left and right side surfaces of the bogie frame 11, respectively, to which the lower ends of height adjustment rods 23 of the automatic height adjustment device 20, which will be described later, are attached.

[0024] The wheelset 12 is configured by press-fitting and fixing a pair of left and right wheels 12a to both ends of an axle 12b. The axle box 13 rotatably supports journals formed at both ends of the axle 12b of the wheelset 12. The axle box 13 includes bearings that support the journals, a lubricating device for the bearings, and auxiliary equipment such as a tachograph that generates output according to the running speed.

[0025] The axle box suspension 14 supports the axle boxes 13 so that they can be displaced vertically relative to the bogie frame 11. The axle box suspension 14 can be configured, for example, as an axle beam type having a swing arm-like axle beam that rotates around an axis provided on the bogie frame 11. A bush made of an elastic material such as rubber is provided at the connection point between the axle beam and the bogie frame 11. The axle box suspension 14 has the function of using the elastic deformation of the bush to displace the left and right axle boxes 13 relative to each other in the longitudinal direction, allowing the wheel sets 12 to be steered, in order to facilitate smooth curved running.

[0026] The axle spring 15 is a spring element provided between the upper part of the axle box 13 and the bogie frame 11 above it. The axle spring 15 generates a reaction force corresponding to the relative vertical displacement between the axle box 13 and the bogie frame 11 caused by the operation of the axle box support device 14. The axle spring 15 has a spring element such as a compression coil spring, for example.

[0027] The axle damper 16 is a hydraulic shock absorber provided in parallel with the axle spring 15 between the axle box 13 and the bogie frame 11. The axle damper 16 generates a damping force according to the vertical relative speed of the axle box 13 with respect to the bogie frame 11. The axle spring 15 and the axle damper 16 work together to form the primary suspension system of the vehicle 1.

[0028] The air springs 17 are provided between the lower part of the car body 2 and the upper part of the bogie frame 11. The air springs 17 are spring elements (pillow springs) that support the weight of the car body 2 and generate a reaction force according to the relative height displacement between the car body 2 and the bogie frame 11. The air springs 17 are configured by introducing compressed air into a diaphragm made of a flexible, elastic material such as rubber. A damping element such as a restrictor is provided inside the air spring 17 to generate a damping force by utilizing the air flow inside the air spring 17 when it expands or contracts.

[0029] The vehicle 1 is equipped with an automatic height adjustment device 20, which will be described below, in order to suppress changes in the height of the air springs 17 (the relative height of the car body 2 with respect to the bogie frame 11) caused by, for example, the number of passengers or the distribution of passengers in the vehicle cabin. The automatic height adjustment device 20 includes a height adjustment valve 21, a height adjustment lever 22, a height adjustment rod 23, etc.

[0030] The height adjustment valve (LV) 21 switches between an air supply state in which air is supplied to the air spring 17, an exhaust state in which air is exhausted from the air spring 17, and a neutral state in which neither air supply nor exhaust is performed, depending on the relative height of the car body 2 to the bogie frame 11 (height of the air spring 17).

[0031] The height adjustment lever (LV lever) 22 is a lever-shaped member that protrudes from the height adjustment valve 21. The height adjustment lever 22 interlocks with the valve body inside the height adjustment valve 21, and its protruding end is connected to the upper end of the height adjustment rod 23. The height adjustment lever 22 is configured to switch the state of the height adjustment valve 21 by rotating (swinging) one end in the vertical direction around an axis provided on the height adjustment valve 21 side. The height adjustment lever 22 cooperates with the height adjustment rod 23 to form an interlocking mechanism that transmits a change in the height of the carbody 2 relative to the bogie frame 11 to the height adjustment valve 21.

[0032] The height adjustment rod (LV rod) 23 is disposed so that its longitudinal direction is along the up-down direction, and is a member (connector) that transmits changes in the relative height of the carbody 2 with respect to the bogie frame 11 to the height adjustment lever 22. The upper end of the height adjustment rod 23 is rotatably connected to one end of the height adjustment lever 22. The lower end of the height adjustment rod 23 is rotatably connected to a bracket 11a of the bogie frame 11. The height adjustment rod 23 is provided with, for example, a screw-type manual length adjustment mechanism (turnbuckle) not shown, and its length can be adjusted manually without using the pneumatic actuator 30 described later. Such manual length adjustment of the height adjustment rod 23 is performed to adjust the vehicle height during normal driving of the vehicle 1, balance the wheel load, and the like.

[0033] Fig. 2 is a schematic diagram showing the operation of the automatic height adjustment device for the vehicle shown in Fig. 1. As shown in Fig. 2(a), when the relative height of the carbody 2 with respect to the bogie frame 11 is in a predetermined intermediate region, the height adjustment valve 21 is in a neutral state (dead band of the height adjustment valve 21) in which neither air is supplied to nor exhausted from the air springs 17. As shown in Fig. 2(b), when the relative height of the carbody 2 with respect to the bogie frame 11 is higher than the upper limit of the intermediate region (the air springs 17 are extended), the height adjustment rod 23 rises relative to the height adjustment valve 21, and the height adjustment valve 21 is in an exhaust state in which it releases part of the air inside the air springs 17 to the atmosphere, thereby exhausting the air, and contracting the air springs 17 to lower the carbody 2 relative to the bogie frame 11.

[0034] As shown in Figure 2(c), when the relative height of the car body 2 with respect to the bogie frame 11 is lower than the lower limit of the intermediate region (the air spring 17 is in a compressed state), the height adjustment rod 23 descends relative to the height adjustment valve 21, and the height adjustment valve 21 supplies compressed air stored in the air reservoir 24 to the air spring 17, expanding the air spring 17 and raising the car body 2 relative to the bogie frame 11. Through this operation, the automatic height adjustment device 20 has the function of maintaining the height of the car body 2 in the intermediate region regardless of the number of passengers, etc. For example, when the train is stopped at a station, the car body 2 can be kept at a substantially constant height even when passengers are getting on and off.

[0035] In the above-described automatic height adjusting device 20, the height adjusting rod 23 is provided with a pneumatic actuator 30, and compressed air stored in an air reservoir 24 can be supplied to this pneumatic actuator 30 via a control valve (not shown). This has the function of suppressing fluctuations in wheel load of the vehicle 1. In this embodiment, the pneumatic actuator 30 is a pneumatic cylinder.

[0036] [Regarding the pneumatic actuator control device 100] (First configuration example) Next, a first configuration example of a pneumatic actuator control device 100 that controls the operation of the above-mentioned pneumatic actuator 30 will be described. Fig. 3 is a block diagram relating to control of the pneumatic actuator control device 100 according to the first configuration example. The pneumatic actuator control device 100 according to the first configuration example may be referred to as a pneumatic actuator control device 100A.

[0037] The pneumatic actuator control device 100 is a control device that controls the operation of the pneumatic actuator 30. The pneumatic actuator 30 includes a cylindrical cylinder 31 and a piston 32 that slides inside the cylinder 31. The piston 32 includes a partition wall 32a and a piston rod 32b.

[0038] As shown in FIG. 3, the pneumatic actuator control device 100 includes a high-pressure tank 110, an air supply adjustment valve 120, a directional control valve 130, an exhaust cutoff valve 140, a reset valve 150, a computer 160, a microcomputer 170, a proportional valve control unit 180, a switching valve control unit 190, and a DA converter 195.

[0039] The high-pressure tank 110 and the air intake adjustment valve 120 are connected by a pipe P1, and the air intake adjustment valve 120 and the direction switching valve 130 are connected by a pipe P2. Similarly, the direction switching valve 130 and the bottom side of the cylinder 31 (hereinafter referred to as the bottom-side inner cylindrical portion 31a) are connected by a pipe P3, and the direction switching valve 130 and the rod side of the cylinder 31 (hereinafter referred to as the rod-side inner cylindrical portion 31b) are connected by a pipe P4.

[0040] The directional control valve 130 and the exhaust cutoff valve 140 are connected by a pipe P5, and one end of an atmosphere release pipe P6 for opening to the atmosphere is connected to the exhaust cutoff valve 140. The reset valve 150 is connected to one end of the pipe P6, and the other end of the pipe P6 is connected to the pipe P2. The reset valve 150 is also connected to one end of an atmosphere release pipe P8 for opening to the atmosphere.

[0041] The high-pressure tank 110 is a tank that stores gas such as high-pressure air to be supplied to the pneumatic actuator 30.

[0042] The air supply adjustment valve 120 is a proportional control valve that can adjust the flow rate of compressed air flowing from the high-pressure tank 110 to the directional control valve 130, and can be, for example, an electromagnetic control valve. In this embodiment, the air supply adjustment valve 120 can adjust the flow rate by adjusting the current value of a direct current of a predetermined voltage (e.g., 24 V or 12 V).

[0043] For example, a direct acting solenoid valve can be used as the directional control valve 130. When a predetermined voltage is applied to this directional control valve 130 to turn it on, compressed air can be supplied from the high-pressure tank 110 to the bottom side inner cylinder portion 31a via pipes P1, P2, and P3, while the rod side inner cylinder portion 31b is opened to the atmosphere via pipes P4 and P5 and an atmosphere opening pipe P6.

[0044] Conversely, when the voltage application to the directional control valve 130 is turned off, compressed air can be supplied from the high-pressure tank 110 to the rod-side inner cylindrical portion 31b of the cylinder 31 via the pipes P1, P2, and P4, but the bottom-side inner cylindrical portion 31a is opened to the atmosphere via the pipes P3 and P5 and the atmosphere-opening pipe P6.

[0045] Furthermore, the exhaust cutoff valve 140 is opened when a predetermined voltage is applied to turn it on, and therefore the air inside the bottom-side inner cylindrical portion 31a or the rod-side inner cylindrical portion 31b is discharged through the atmosphere open pipe P6.

[0046] Conversely, when the predetermined voltage is turned off, the exhaust cutoff valve 140 is closed, and the air in the bottom-side inner cylindrical portion 31a or the rod-side inner cylindrical portion 31b is not discharged through the pipes P4, P5 and the atmosphere open pipe P6. Therefore, by turning off the exhaust cutoff valve 140 and blocking the discharge of air from the atmosphere open pipe P6, it is possible to hold the partition wall 32a of the piston 32 at an intermediate position rather than at the stroke end of the cylinder 31.

[0047] Similarly to the above-described exhaust cutoff valve 140, the reset valve 150 opens when a predetermined voltage is applied to turn it on, and closes when the application of that voltage is turned off. This reset valve 150 is a valve for reducing the high-pressure air in the cylinder 31 from the same pressure as that of the above-described high-pressure tank 110 when the partition wall 32a of the piston 32 reaches the stroke end on the bottom side or rod side of the cylinder 31.

[0048] That is, when the partition wall 32a of the piston 32 reaches the stroke end of the bottom side or rod side of the cylinder 31 due to the supply of high-pressure air from the high-pressure tank 110, the pressure inside the bottom side inner cylindrical portion 31a or the rod side inner cylindrical portion 31b (one of the pressures inside the cylinder 31) becomes equal to the pressure inside the high-pressure tank 110.

[0049] In this state, even if the directional control valve 130 is switched to supply high-pressure compressed air to the other side of the cylinder 31 (the side opposite to the side that has reached the stroke end), the same pressure as that of the high-pressure tank 110 is applied to the other side of the cylinder 31, regardless of the opening of the air intake adjustment valve 120. Therefore, the speed adjustment function of the piston 32 by controlling the air intake adjustment valve 120, which is a proportional control valve, does not work.

[0050] To prevent the speed adjustment function from failing after the stroke end is reached, a reset valve 150 is provided to release one side of the pressure in the cylinder 31 via an atmosphere release pipe P8.

[0051] The computer 160 receives input from the user and transmits commands based on the input to the microcomputer 170. The computer 160 may be a personal computer.

[0052] Based on commands from computer 160, microcomputer 170 sends to switching valve control unit 190 on / off signals related to the operation of directional control valve 130, exhaust cutoff valve 140, and reset valve 150. Based on commands from computer 160, microcomputer 170 also sends to DA converter 195 a signal related to the opening degree of intake air regulating valve 120 (for example, a voltage command).

[0053] The computer 160 and the microcomputer 170 are each equipped with a RAM (Random Access Memory), a ROM (Read Only Memory), a CPU (Central Processing Unit), an interface, etc., but the computer 160 and the microcomputer 170 may be integrated into one. The computer 160 and the microcomputer 170 correspond to a main control unit.

[0054] Proportional valve control unit 180 outputs a current corresponding to the voltage applied from DA converter 195 to air supply adjustment valve 120. As a result, proportional valve control unit 180 controls the opening of air supply adjustment valve 120 according to the value of the output current. Note that proportional valve control unit 180 can be configured with a constant current circuit using an operational amplifier and a FET (Field Effect Transistor).

[0055] The switching valve control unit 190 controls the on / off switching of the directional switching valve 130, exhaust cutoff valve 140, and reset valve 150 based on on / off signals from the microcomputer 170. Note that a FET switching circuit can be used for the switching valve control unit 190. Note that the switching valve control unit 190 corresponds to the directional switching valve control unit, exhaust cutoff valve control unit, and reset valve control unit.

[0056] Furthermore, the DA converter 195 outputs a voltage based on a command from the microcomputer 170 to the proportional valve control section 180. As a result, the proportional valve control section 180 outputs a current value corresponding to the voltage to the supply air adjustment valve 120.

[0057] (About the action) The operation of the pneumatic actuator control device 100 configured as above will be described below.

[0058] (When the pneumatic actuator is extended) 3, when the pneumatic actuator 30 is extended, the proportional valve control unit 180 controls the operation of the air supply adjustment valve 120 so that it opens by a predetermined amount. In addition, the switching valve control unit 190 controls the operation of the directional switching valve 130 and the exhaust cutoff valve 140 so that they are turned on, while the reset valve 150 is turned off.

[0059] Then, compressed air from the high-pressure tank 110 is supplied to the bottom-side inner cylinder portion 31a via the pipe P1, the air supply adjustment valve 120, the pipe P2, the direction switching valve 130, and the pipe P3. At the same time, the air in the rod-side inner cylinder portion 31b is released to the atmosphere via the pipe P4, the direction switching valve 130, the pipe P5, the exhaust cutoff valve 140, and the atmosphere release pipe P6.

[0060] Therefore, as the high-pressure air is supplied to the bottom-side inner cylindrical portion 31a, the piston 32 is pushed out of the cylinder 31, and the piston 32 extends.

[0061] (When the pneumatic actuator is contracted) Next, when the pneumatic actuator 30 is to be contracted, the proportional valve control unit 180 controls the operation of the air supply adjustment valve 120 so that it opens by a predetermined amount. In addition, the switching valve control unit 190 controls the operation of the directional switching valve 130 so that it is turned off, the exhaust cutoff valve 140 so that it is turned on, and the reset valve 150 so that it is turned off.

[0062] Then, compressed air from the high-pressure tank 110 is supplied to the rod-side inner cylinder portion 31b via the pipe P1, the air supply adjustment valve 120, the pipe P2, the directional control valve 130, and the pipe P4. At the same time, the air in the bottom-side inner cylinder portion 31a is released to the atmosphere via the pipe P3, the directional control valve 130, the pipe P5, and the atmosphere release pipe P6.

[0063] Therefore, as high-pressure air is supplied to the rod-side inner cylindrical portion 31b, the piston 32 is pushed into the cylinder 31, causing the piston 32 to contract.

[0064] (About the speed adjustment function of pneumatic actuators) In the above-described pneumatic actuator 30, the amount of compressed air flowing per unit time into the bottom-side inner cylinder portion 31 a or the rod-side inner cylinder portion 31 b can be adjusted by controlling the opening of the air supply adjustment valve 120 using the proportional valve control unit 180. This makes it possible to adjust the speed of the piston 32.

[0065] (Regarding intermediate position holding of pneumatic actuators) Next, the holding of the intermediate position of the pneumatic actuator 30 will be described. In this case, as described above, the pneumatic actuator 30 is extended or retracted for a predetermined time period, and after the partition wall 32a of the piston 32 is positioned at a predetermined position, the proportional valve control unit 180 controls the operation of the intake air adjustment valve 120 to close it. In addition, the switching valve control unit 190 controls the operation of the directional switching valve 130 to an arbitrary OFF or ON state, the exhaust cutoff valve 140 to OFF (closed), and the reset valve 150 to OFF (closed).

[0066] As a result, compressed air from the high-pressure tank 110 is not supplied to either the bottom-side inner cylinder portion 31a or the rod-side inner cylinder portion 31b. In addition, the air inside the bottom-side inner cylinder portion 31a and the rod-side inner cylinder portion 31b is not exhausted from either the exhaust cutoff valve 140 or the reset valve 150.

[0067] Therefore, the partition wall 32a of the piston 32 can be held at a desired intermediate position.

[0068] (Regarding pressure relief for pneumatic actuators) Next, we will explain pressure release of the pneumatic actuator 30. Note that the purpose of pressure release here is to operate the reset valve 150 when the partition wall 32a of the piston 32 reaches the stroke end on the bottom side or rod side of the cylinder 31, thereby maintaining the speed adjustment function of the pneumatic actuator 30.

[0069] In this case, the proportional valve control unit 180 controls the operation of the air supply adjustment valve 120 so as to close it. Also, the switching valve control unit 190 turns the directional control valve 130 on or off so that either the bottom-side inner cylinder portion 31a or the rod-side inner cylinder portion 31b, into which high-pressure air has already been introduced, communicates with the directional control valve 130. Meanwhile, the switching valve control unit 190 controls the operation of the reset valve 150 so as to turn it on, but controls the operation of the exhaust cutoff valve 140 so as to be either on or off.

[0070] Then, the high-pressure air introduced into the bottom-side inner cylindrical portion 31a or the rod-side inner cylindrical portion 31b is released to the atmosphere via pipe P3 or pipe P4, directional control valve 130, pipe P2, pipe P7, reset valve 150 and atmosphere release pipe P8.

[0071] Therefore, since the high-pressure air is discharged from the bottom-side inner cylinder portion 31 a or the rod-side inner cylinder portion 31 b, when the high-pressure air from the high-pressure tank 110 is subsequently supplied to either the bottom-side inner cylinder portion 31 a or the rod-side inner cylinder portion 31 b (one chamber), no high-pressure air remains in the other chamber on the opposite side of the partition wall 32 a from the one chamber. Therefore, by adjusting the flow rate of the high-pressure air with the air supply adjustment valve 120, the speed of the piston 32 can be adjusted.

[0072] [Note] The contents described in the first configuration example above can be understood, for example, as follows. [1] That is, the pneumatic actuator control device 100 according to the first configuration example includes a high-pressure tank 110 that supplies compressed air, an intake adjustment valve 120 that adjusts the flow rate of the compressed air supplied from the high-pressure tank 110, a proportional valve control unit 180 that controls the opening and closing of the intake adjustment valve 120, and a cylinder 31 having a bottom-side inner cylindrical portion 31a (one chamber) and a rod-side inner cylindrical portion 31b (the other chamber) that are separated by a piston 32 in the cylinder 31. The direction switching valve 130 supplies and exhausts air, and is configured to be selectively switchable between a first state in which air can be supplied to the bottom side inner cylindrical portion 31a (one chamber) and exhausted from the rod side inner cylindrical portion 31b (the other chamber), and a second state in which air can be supplied to the rod side inner cylindrical portion 31b (the other chamber) and exhausted from the bottom side inner cylindrical portion 31a (one chamber), and is equipped with a switching valve control portion 190 (directional switching valve control portion) that switches the direction switching valve 130 between the first state and the second state.

[0073] When configured in this manner, the directional control valve 130 is configured to alternately supply and exhaust compressed air, the flow rate of which is adjusted by the air supply adjustment valve 120, to the bottom-side inner cylinder portion 31a (one chamber) and the rod-side inner cylinder portion 31b (the other chamber) that are isolated by the piston 32 in the cylinder 31. Therefore, using one switching valve control unit 190 (directional control valve control unit) and one proportional valve control unit 180, it is possible to control how much compressed air is supplied to either the bottom-side inner cylinder portion 31a (one chamber) or the rod-side inner cylinder portion 31b (the other chamber) in one pneumatic actuator 30. In other words, these controls can be performed with a simple configuration.

[0074] [2] In addition, the first configuration example described above further includes an exhaust shutoff valve 140 that enables the exhaust to be shut off via the directional control valve 130, a switching valve control unit 190 (exhaust control unit) that controls the exhaust shutoff by the exhaust shutoff valve 140, and a computer 160 and a microcomputer 170 (main control unit) that control the proportional valve control unit 180 and the switching valve control unit 190 (directional control valve control unit and exhaust shutoff control unit) to control the position of the piston 32 in the cylinder 31.

[0075] With this configuration, the proportional valve control unit 180 can control the flow rate of compressed air supplied from the air intake adjustment valve 120, and the switching valve control unit 190 (directional switching valve control unit and exhaust cutoff control unit) can control the operation of the directional switching valve 130 and the exhaust cutoff valve 140. Therefore, the position of the partition wall 32a of the piston 32 in the cylinder 31 can be controlled to a position according to the amount of air remaining in the bottom-side inner cylindrical portion 31a (one chamber) and the rod-side inner cylindrical portion 31b (the other chamber). That is, a ramp response test can be performed in addition to a step response test.

[0076] [3] Furthermore, in the above-described first configuration example, when the piston 32 has reached one stroke end of the cylinder 31 and is to be moved toward the other stroke end, a reset valve 150 is provided to release the pressure in the cylinder 31, and a switching valve control unit 190 (reset valve control unit) is provided to control the release of the pressure in the cylinder 31 by the reset valve 150, and the switching valve control unit 190 (directional switching valve control unit) switches the position of the directional switching valve 130 after the pressure in the cylinder 31 is released.

[0077] In this configuration, when the piston 32 has reached one stroke end of the cylinder 31 and is to be moved toward the other stroke end, the position of the directional control valve 130 is switched after the pressure inside the cylinder 31 is released by the reset valve 150, so that the piston 32 can be moved at a speed that corresponds to the flow rate of compressed air.

[0078] (Second configuration example) The following describes a second configuration example of the pneumatic actuator control device 100. Fig. 4 is a block diagram related to control of the pneumatic actuator control device 100 according to the second configuration example. The pneumatic actuator control device 100 according to the second configuration example may be referred to as a pneumatic actuator control device 100B.

[0079] The pneumatic actuator control device 100A according to the first configuration example is an open-loop control device, but the pneumatic actuator control device 100B according to the second configuration example is a feedback control device. Specifically, the air supply adjustment valve 120 is subjected to speed feedback control.

[0080] The feedback control unit 200 for performing such feedback control is functionally realized based on the components of the pneumatic actuator control device 100 described above, as well as a sensor for detecting the position of the piston 32 of the pneumatic actuator 30. In the feedback control unit 200, the parts that perform various calculations (computations) are functionally realized based on programs executed by the computer 160 and the microcomputer 170, and data loaded into these. The speed command given to the feedback control unit 200 is given by the computer 160.

[0081] 4, feedback control unit 200 has speed control unit 300 that performs feedback control regarding speed. Speed ​​control unit 300 has speed controller 310, controlled object 320, speed calculation unit 330, first subtraction point 340, second subtraction point 341, and first addition point 350.

[0082] This speed controller 310 is functionally provided with a proportional valve control section 311 and an on / off valve control section 312. Proportional valve control section 311 is a section that receives a speed command output from first output point 340 and a speed deviation output from first summing point 350, performs a predetermined calculation based on the speed command and the speed deviation, and outputs a command related to the opening of air supply regulation valve 120 to air supply regulation valve 120, which is controlled object 320.

[0083] Furthermore, on / off valve control section 312 outputs a command relating to the on / off of directional control valve 130 to directional control valve 130, which is control object 320, based on a speed command input from first outlet 340. Similarly, on / off valve control section 312 outputs a command relating to the on / off of exhaust cutoff valve 140 to exhaust cutoff valve 140, which is control object 320, and outputs a command relating to the on / off of reset valve 150 to reset valve 150, which is control object 320.

[0084] As described above, the controlled objects 320 are the intake air adjustment valve 120, the directional control valve 130, the exhaust shut-off valve 140, and the reset valve 150, but may also include fluctuations in the air flow rate obtained by the operation of each of these valves and the position of the piston 32 (piston position).

[0085] The velocity calculation unit 330 receives piston position information (hereinafter referred to as piston position) regarding the position of the piston 32 obtained from the first withdrawal point 340, calculates the piston velocity, which is the velocity of the piston 32, from the change in the piston position over time, and outputs the piston velocity to the first addition point 350.

[0086] First output point 340 outputs the piston position to the outside and also outputs it to the speed calculation unit 330. Second output point 341 outputs a speed command to first summing point 350, proportional valve control unit 311, and on / off valve control unit 312. First summing point 350 calculates a speed deviation from the speed command and the piston speed.

[0087] (Details of speed control of pneumatic actuator control device 100B) Next, the speed control of the pneumatic actuator control device 100B will be described in detail below. Note that the following speed control is realized by the speed control section 300 included in the feedback control section 200.

[0088] First, the equation of motion of the piston 32 can be expressed as the following equation (1).

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[0089] Here, for the internal pressures P1 and P2 of the cylinder 31 in equation (1), the following equations (2) and (3) hold for the air mass m1 on the internal pressure P1 side and the air mass m2 on the internal pressure P2 side according to the gas state equation.

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[0090] After determining A1P1 and A2P2 from the above equations (2) and (3), they are substituted into the equation of motion of equation (1), resulting in the following equation (4).

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[0091]

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[0092] Incidentally, in the above formula (4), if the length of the pipeline P3 or the pipeline P4 is long enough, it can be considered that |x| << L. Therefore, when the right side of the above formula (4) is linearly approximated in the vicinity of x = 0, the following formula (6) is obtained.

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[0093] From the above formula (6), the equations of motion of the cylinder 31 and the piston 32 can be expressed as the following formulas (7) and (8) in the state space representation.

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[0094] Next, in the pneumatic actuator control device 100B as shown in FIG. 4 described above, a mathematical model corresponding to the presence of each valve is calculated as follows. Hereinafter, it is assumed that the direction switching valve 130 is in the on state, that is, the piston 32 is controlled in the extending direction. This is because even when the direction switching valve 130 is off, only the symbols of the following formulas are interchanged, and the same formulas hold.

[0095] The balance of the air mass flowing into or out of the bottom side inner cylinder portion 31a of the pneumatic actuator 30 can be expressed as the following formula (9) from the mass flow conservation side.

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[0096] Also, if the effective cross-sectional area of the flow path of the air supply regulating valve 120 is A sup and the effective cross-sectional area of the reset valve 150 is A ex then it can be expressed as the following formulas (10) and (11).

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[0097] Here, A in the above equation (10) sup is the effective cross-sectional area of ​​the air supply adjustment valve 120, which is a proportional control valve, and can be continuously adjusted (the cross-sectional area changes). On the other hand, A in the above equation (11) ex It should be noted that μ(p 1 , p2) is a nonlinear function as shown in the following equation (12) (p1 and P 1 、 p2 and P2 represent the internal pressure of the same cylinder 31).

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[0098] By substituting the above equations (10) and (11) into equation (9), the following equation (13) is obtained.

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[0099] On the other hand, when it comes to the balance of air mass in the rod-side inner cylinder portion 31b of the pneumatic actuator 30, it is sufficient to consider only the outflow of air from the exhaust cutoff valve 140. First, when the exhaust cutoff valve 140 is closed, there is no exchange of air with the atmosphere, and this can be expressed as in the following equation (14).

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[0100] It is also assumed that when the exhaust cutoff valve 140 is open, the effective cross-sectional area of ​​the flow path of the exhaust cutoff valve 140 is sufficiently large and the state of the air in the rod side inner cylindrical portion 31b changes quasi-statically. That is, the state of the air in the rod side inner cylindrical portion 31b follows the equation of state shown in the following formula (15).

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[0101] Then, P2=P0 because the rod side inner cylindrical portion 31b is open to the atmosphere through the exhaust cutoff valve 140. Therefore, it can be expressed as in equation (16).

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[0102] To summarize the above, the dynamic system of the piston 32 controlled by the above-described pneumatic actuator control device 100B is expressed by the following equation (17) when the exhaust cutoff valve 140 is closed.

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[0103] Moreover, when the exhaust cutoff valve 140 is open, the following equation (18) holds.

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[0104] The state variables of the above dynamic system are (v, x, m1, m2), and in order to close the system of equations, it is necessary to express all of the right-hand sides using state variables and constants. To do this, first, rearrange the equations when the exhaust cutoff valve 140 is closed. The internal pressure P1 of the bottom-side inner cylindrical portion 31a can be expressed as the following equation (19) using the gas state equation:

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[0105] Therefore, the right side of the third equation of equation (17) can be expressed in terms of m1 and x. Furthermore, m2 does not change from the initial state, as can be seen from the fourth equation of equation (17). Therefore, the pressure in the rod-side inner cylindrical portion 31b is equal to the atmospheric pressure in the initial state, and the piston 32 is at the stroke end x of the bottom-side inner cylindrical portion 31a. btm Assuming that we start from , it can be expressed as the following equation (20).

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[0106] Next, rearranging equation (18), which is the equation when the exhaust shutoff valve 140 is open, the right-hand side of the third equation of equation (18) is the same as when the exhaust shutoff valve 140 is closed. Furthermore, to find V2 on the right-hand side of the fourth equation, V2 is expressed as shown in the following equation (21).

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[0107] Therefore, V2 can be expressed as in equation (22).

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[0108] From the above equation (22), the fourth equation of equation (18) can be expressed as equation (23), and the right-hand side of the third equation can be expressed entirely using state variables and constants.

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[0109] Here, to simplify the notation in each formula, each character in the formula is written as in the following formula (24).

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[0110] Then, the state space expression (equation (18)) when the exhaust cutoff valve 140 is open can be rewritten as the following equation (25).

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[0111] By differentiating both sides of the first equation above with respect to time and representing the fourth equation as the first equation, we obtain the following equation (26).

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[0112] By differentiating both sides of the first equation of the above equation (25) with respect to time and substituting the fourth equation into the first equation, we obtain the following equation (26).

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[0113] Here, the coefficient of the second term in the final equation in equation (26) can be expressed as in the following equation (27).

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[0114] Here, m2>0, L+x>0, RT>0, and furthermore, since air is being supplied from the bottom-side inner cylindrical portion 31a, A1P1≧A2P2, and therefore the coefficients are all always negative. Hereinafter, for the sake of simplicity, we will write ξ:=-σ{λ2(L+x)-(m1-m2)}.

[0115] To eliminate m1 in equation (26), consider the third equation of equation (25). First, since the reset valve 150 is normally closed, A ex On the other hand, for the air supply adjustment valve 120, under the following conditions, the function μ(P T ,P1) is a constant. [Condition 1]: High-pressure tank pressure P T In comparison, the pressure P1 in the bottom-side inner cylindrical portion 31a is sufficiently small and is below the critical pressure ratio. [Condition 2]: High-pressure tank pressure P T is kept constant by a regulator.

[0116] Therefore, the function μ(P T ,P1) as a constant μ T When substituted, the following equation (28) is obtained.

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[0117] Substituting this equation (28) into equation (26), rearranging and rearranging, we obtain the following equation (29).

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[0118] From the above equation (29), the target speed v ref For example, the proportional gain for the speed is K p and can be designed as shown in the following equation (30).

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[0119] Or, the above σ(Lx)μ T is always a positive value, and considering that a change in x does not affect the stability of the control system, it is also possible to design a controller of the form shown in equation (31).

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[0120] For example, substituting equation (30) into equation (29) and rearranging it gives equation (32).

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[0121] In this case, since we are considering an air supply system to the bottom-side inner cylindrical portion 31a, it is implicitly understood thatref It is assumed that v is >0. ref <0, a similar differential equation is derived by turning off the directional control valve 130. The equilibrium point v* of this system can be obtained as equation (33) by substituting v¨ = 0, v = 0 and solving for v.

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[0122] In other words, although steady-state deviation occurs, K p >>ξ, then v* ≒ v ref It can be seen that the equilibrium point and the target speed coincide. Furthermore, considering the variable transformation ν=vv*, equation (32) can be expressed as the following equation (34).

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[0123] Here, (ξ+K p )v*-K p v ref Note that =0, this can be transformed into the following equation (35).

[0124] In other words, although steady-state deviation occurs, K p >>ξ, then v* ≒ v ref It can be seen that the equilibrium point and the target speed coincide. Furthermore, considering the variable transformation ν=vv*, equation (32) can be expressed as the following equation (34).

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[0125] The above equation (35) is a second-order differential equation with respect to the variable ν, and if c+∂f / ∂v>0, the equilibrium point v=v* (i.e., ν=0) is clearly asymptotically stable.

[0126] The above discussion of the equation is a consideration of stability when equation (30) can be applied strictly. However, in reality, equation (30) cannot be directly implemented as the speed controller 310. This is because A sup is the opening of the air supply adjustment valve 120 and cannot take a negative value. To solve this, for example, it is possible to operate the directional control valve 130 when the control command becomes a negative value, but there is a concern that the control system may become unstable due to a delayed response of the directional control valve 130. Therefore, instead of equation (30), the control law expressed by the following equation (36) is applied.

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[0127] However, in the above equation (36), ramp(y) is a unit ramp function and satisfies the following equation (37).

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[0128] That is, this is the control law that when the manipulated variable is a positive value, the controller applies equation (32), and when it is a negative value, the controller closes the air intake adjustment valve 120. By substituting this into equation (29), the speed controller 310 controls the air intake adjustment valve 120 based on the following equation (38).

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[0129] Following the above discussion, we consider the equilibrium point of the system expressed by equation (38). That is, we consider finding the solution to the following equation (39).

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[0130] However, since the ramp function is nonlinear and has non-differentiable points, it is difficult to simply solve the above equilibrium equation. Therefore, in equation (39), v*-v ref <0 and v*-v ref Let's consider the case of ≧0. First, v*-v ref If ≧0, always ramp(-(v*-v ref ))=0, so equation (40) must hold.

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[0131] However, in this case, the premise is v*-v ref ≧0→v*≧v ref Since we are considering the case of v*=0, v ref ≦0. This is because v*-v required for a system that assumes air supply to the bottom-side inner cylindrical portion 31a ref > 0. Therefore, in reality, v*-v ref In the region ≧0, v ref >0, there is no equilibrium point. On the other hand, even if a negative target velocity is commanded to this system, the piston velocity will not become negative, i.e., the piston 32 will not retract but will simply stop. In order to retract the piston 32, the system itself must be switched using the directional control valve 130.

[0132] On the other hand, v*-v ref If <0, ramp(-(v*-v ref ))=-(v*-v ref ), the equilibrium equation is the same as when the controller of equation (30) is applied. The solution to the equilibrium equation in this case is v*-v ref <0, the equilibrium point of the system can be expressed by equation (33), even in the control law using a ramp function. Also, as for stability, since equation (38) and equation (32) are the same system, at least in the vicinity of the equilibrium point, if c+∂f / ∂v>0, the equilibrium point v=v* is asymptotically stable. On the other hand, v*-v refIf ≧0, the system equation becomes the following equation (41).

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[0133] Therefore, formally, v=0 is asymptotically stable. However, v*-v ref In the process of asymptotically approaching v=0 from the state ≧0, v <v ref Since v=v* becomes asymptotically stable when c+∂f / ∂v>0, the equilibrium point v=v* is also globally asymptotically stable.

[0134] In the pneumatic actuator control device 100B according to the second configuration example described above, in addition to the effects achieved by the pneumatic actuator control device 100 according to the first configuration example described above, the opening of the air supply adjustment valve 120 can be adjusted with high precision by performing control based on the calculation formula (38) in the feedback control unit 200 having the speed controller 310.

[0135] (Third configuration example) The following describes a third configuration example of the pneumatic actuator control device 100. Fig. 5 is a block diagram related to control of the pneumatic actuator control device 100 according to the third configuration example. The pneumatic actuator control device 100 according to the third configuration example may be referred to as a pneumatic actuator control device 100C.

[0136] The pneumatic actuator control device 100C according to the third configuration example is improved to prevent instability in the speed control by the speed controller 310 of the pneumatic actuator control device 100B according to the second configuration example. That is, the speed controller 310 is provided with a slip symptom detection unit 313, a third subtraction point 342, a fourth subtraction point 343, a first multiplication point 361, and a second multiplication point 362.

[0137] The slip symptom detection unit 313 receives the speed deviation output from the first summation point 350 and the piston speed v output from the speed calculation unit 330. Based on the speed deviation and the piston speed v, the slip symptom detection unit 313 detects whether the absolute value of the piston speed v exceeds the absolute value of the estimated equilibrium speed value ^v*. In other words, it detects whether |v|>|^v*|.

[0138] Then, when it is detected that the absolute value of the piston speed v exceeds the absolute value of the estimated equilibrium speed value ^v* (i.e., when |v|>|^v*|), the slip symptom detection unit 313 outputs a signal (a signal of "0") to the first multiplication point 361 and the second multiplication point 362 to prioritize the operation of closing the intake air adjustment valve 120 and the exhaust cut-off valve 140.

[0139] Conversely, if the absolute value of the piston speed v is detected to be less than or equal to the absolute value of the estimated equilibrium speed value ^v* (i.e., if |v|≦|^v*|), the slip symptom detection unit 313 does not output a signal to prioritize the operation of closing the intake air adjustment valve 120 and the exhaust cutoff valve 140, but instead outputs a signal (a signal of "1") to maintain the current operating state.

[0140] The third output point 342 outputs the piston position to the first summation point 350 and the slip symptom detection unit 313. The fourth output point 343 outputs the signal from the slip symptom detection unit 313 to the first multiplication point 361 and the second multiplication point 362.

[0141] Furthermore, the first multiplication point 361 receives as input the signal output from the proportional valve control unit 311 and the signal output from the slip symptom detection unit 313, multiplies these signals, and outputs the result to the intake air regulation valve 120, which is the controlled object 320. Therefore, when a signal of "0" is input from the slip symptom detection unit 313, the result of the multiplication becomes "0", and so the first multiplication point 361 outputs a signal of "0" corresponding to the operation of closing the intake air regulation valve 120 to the intake air regulation valve 120. At this time, the effective cross-sectional area A sup is A sup=0.

[0142] On the other hand, when a signal of "1" is input from slip symptom detection unit 313, the result of the multiplication remains the output from proportional valve control unit 311, so first multiplication point 361 outputs a command value based on equation (36) to intake air adjustment valve 120. At this time, the nonlinear compensation coefficient 1 / {σ(Lx)μT} in equation (36) is treated as a constant since it has little effect on stability, and the proportional gain K p In this case, the first multiplication point 361 is set as a command value based on the equation (36), A sup =K p ramp(-(v*-v ref )).

[0143] Similarly, second multiplication point 362 receives as input a signal output from on-off valve control unit 312 and a signal output from slip symptom detection unit 313, multiplies these signals, and outputs the result to exhaust cutoff valve 140, which is controlled object 320. Therefore, when a signal of "0" is input from slip symptom detection unit 313, the multiplication result is "0", so second multiplication point 362 outputs a signal of "0" corresponding to the operation of closing exhaust cutoff valve 140 to exhaust cutoff valve 140. On the other hand, when a signal of "1" is input from slip symptom detection unit 313, the multiplication result remains the output from on-off valve control unit 312, so regardless of whether the output from on-off valve control unit 312 is "1", corresponding to the opening of exhaust cutoff valve 140, or "0", corresponding to the closing of exhaust cutoff valve 140, second multiplication point 362 outputs the signal as is to exhaust cutoff valve 140.

[0144] In addition, in calculating the estimated equilibrium velocity ^v*, it is experimentally determined that ^v*=av ref It should be noted that, in the experiment relating to the third configuration example, the coefficient a was set to, for example, 0.76, but it goes without saying that other values ​​may also be used.

[0145] In the pneumatic actuator control device 100C according to the third configuration example described above, in addition to the effects achieved by the pneumatic actuator control device 100B according to the second configuration example described above, by being provided with a slip symptom detection unit 313, it becomes possible to reduce the average speed of stick-slip motion (stick-slip phenomenon) to a certain extent.

[0146] (Fourth configuration example) The following describes a fourth configuration example of the pneumatic actuator control device 100. Fig. 6 is a block diagram related to control of the pneumatic actuator control device 100 according to the fourth configuration example. The pneumatic actuator control device 100 according to the fourth configuration example may be referred to as a pneumatic actuator control device 100D.

[0147] The feedback control unit 200 of the pneumatic actuator control device 100D according to the fourth configuration example has, in addition to the speed control unit 300 provided in the pneumatic actuator control device 100C according to the third configuration example, a position control unit 400 that has the speed control unit 300 as a local feedback system.

[0148] Position control section 400 is a feedback control loop for position located outside speed control section 300. Position control section 400 includes a position controller 410 and a second summing point 420.

[0149] The position controller 410 receives the position deviation from the second summing point 420, performs a predetermined calculation on the position deviation to calculate a speed deviation, and outputs the speed deviation to the first summing point 350. The position controller 410 is equipped with an anti-windup integrator 411, which will be described later.

[0150] Further, the second summing point 420 calculates a position deviation from the position command and the piston position output from the first pull-out point 340 described above.

[0151] (Details of position control of the pneumatic actuator control device 100D) Next, the position control of the pneumatic actuator control device 100D will be described in detail below. The following position control is realized by the position control unit 400 included in the feedback control unit 200.

[0152] target position x ref As a basic form of a position controller for the fourth configuration, first, the investigation starts from the PI control law as shown in the following equation (42).

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[0153] In the above equation (42), the differential term is omitted because frictional force generally acts sufficiently and a large damping effect can be expected in the control of the pneumatic actuator 30. Instead, an integral compensation term is introduced because it is expected that steady-state deviation will increase due to static friction and the reaction force from the height adjustment rod (LV rod) 23. However, the results of separate speed control experiments have made it clear that if the command speed is too large, slip motion with a large amount of slip occurs and speed control will not be effective. Therefore, the command speed output by the position controller 410 is limited to a certain range using a saturation function as shown in the following equation (43).

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[0154] In the above equation (45), the saturation function sat satisfies the following equation (44).

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[0155] It is generally known that when integral control and a saturation function are used together, the integral value of the deviation may accumulate more than necessary when the manipulated variable is saturated, resulting in a phenomenon known as windup, in which large overshoots or undershoots occur. Therefore, we introduce the anti-windup integrator described below. First, we rewrite the saturation-type PI controller shown in equation (42) above and equation (45) below as a discrete-time system, as equations (46) and (47).

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[0156] In the above, k is an integer index representing the passage of time, and Δt is a control period. In the discrete-time expression of the control law, the position integrator shown in equation (45) is replaced with a position controller 410 (anti-windup integrator 411) that does not perform further integration when the manipulated variable is saturated, as shown in the following equation (48).

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[0157] As described above, the pneumatic actuator control device 100D according to the fourth configuration example has a position control section 400, which in turn has a position controller 410 having an anti-windup integrator 411. Therefore, in addition to the effects achieved by the pneumatic actuator control device 100C according to the third configuration example, the position accuracy of the piston 32 can be improved to a certain degree based on position control, although there may be cases where the response diverges in an oscillatory manner to a certain degree.

[0158] (Fifth configuration example) The following describes a fifth configuration example of the pneumatic actuator control device 100. Fig. 7 is a block diagram related to control of the pneumatic actuator control device 100 according to the fifth configuration example. The pneumatic actuator control device 100 according to the fifth configuration example may be referred to as a pneumatic actuator control device 100E.

[0159] The feedback control unit 200 of the pneumatic actuator control device 100E according to the fifth configuration example is improved so that, in addition to the configuration of the pneumatic actuator control device 100C according to the fourth configuration example, the position controller 410 of the position control unit 400 is equipped with a position feedback disabling unit 412 in addition to an anti-windup integrator 411.

[0160] In the speed control section 300, the speed controller 310 is improved so as to include a speed command excess detection section 314.

[0161] In addition, the position control unit 400 has a signal inverting unit 430, a fourth subtraction point 440, a fifth subtraction point 441, a third multiplication point 450, a fourth multiplication point 451, and a third addition point 421. These will be described in detail below.

[0162] In some experiments with the fourth configuration example described above, oscillatory response divergence was observed in some cases, and it was found that the direct cause of this was a response delay in speed control. A direct method to resolve this response delay would be to improve the response delay in the speed control system, but this is not easy, as there are many elements that require hardware improvements, such as the response delay of the directional control valve 130 and friction between the cylinder 31 and piston 32.

[0163] On the other hand, as mentioned above, although the direct cause is a delayed response in speed control, the trigger is slippage caused by friction, and it is thought that there is a high risk of response divergence, especially when a single slippage causes the target position to be greatly exceeded and the speed command value to change significantly to the opposite sign. In other words, it can be said that the continued application of feedback to the target position when slippage occurs is an indirect cause of oscillatory response divergence.

[0164] Based on such considerations, the pneumatic actuator control device 100E according to the fifth configuration example is provided with a function that "disables feedback control for the target position when slip motion is detected" (i.e., a position feedback disabling unit 412 is provided).

[0165] In other words, once slippage is detected, the control is, so to speak, "overdue" until the slippage subsides, and after the slippage subsides, the position feedback invalidation unit 412 functions to attempt control toward the target position again.

[0166] Here, the "detection of slip motion" can be based on the estimated value of the equilibrium speed, as in the case of preventing instability in speed control, but in order to minimize the frequency of slip motion detection, it is decided to use the target speed as the reference. Specifically, the command speed exceeding signal s k is defined as the following equation (49).

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[0167] However, v th, slip is the threshold value for determining whether the command speed is exceeded (overspeed determination threshold), and the command speed exceedance detection is performed only when the speed command is equal to or greater than a certain value. k If =0, the normal saturation type PI control is applied.

[0168] On the other hand, s kIf =1, the speed command v ref,k is determined as shown in the following equation (50).

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[0169] where sign(y) is the sign function, v s is v s >v th, slip At the same time, the integral compensation term is v I ref, k In other words, when an excessive command speed is detected, the speed command excess detection unit 314 functions to continue issuing a speed command in the same direction as in the control cycle one step before. k While this is set to 1, no feedback control is performed on the target position.

[0170] where v k If the piston speed is |v|, the slip motion will stop. k |≦v s Then, the feedback becomes effective again. Note that, as mentioned above, the integral compensation term is v I ref, k The reason for resetting to 0 is that the situation, such as the positional relationship between the position of the piston 32 and the target position, may change significantly before and after the slip motion, and this is to prevent a deterioration in response due to carrying over the integral value before the command speed was exceeded.

[0171] In order to have the above-mentioned functions, the speed command excess detection unit 314 receives the piston speed from the first pull-out point 340 and the speed command from the anti-windup integrator 411. Then, the speed command excess detection unit 314 performs calculations based on the equation (49) to generate the command speed excess signal s k and outputs either "0" or "1".

[0172] Furthermore, the position feedback invalidation unit 412 performs calculations based on the above equation (50) and calculates the integral compensation term v I ref, k =0 and reset the calculation.

[0173] The signal inverting unit 430 also inverts the command overspeed signal s k The fourth output point 440 outputs the piston position output from the first output point 340 to the third output point 342 and the speed command excess detection unit 314. The fifth output point 441 inverts (switches) the command speed excess signal s output from the speed command excess detection unit 314. k is output to the signal inverter 430 and the fourth multiplication point 451.

[0174] The third multiplication point 450 multiplies the command overspeed signal s output from the fifth subtraction point 441 by k and the output based on equation (50) output from position feedback invalidation unit 412 are input, and these are multiplied together and output to third summing point 421.

[0175] The fourth multiplication point 451 multiplies the command overspeed signal s output from the signal inverting unit 430 by k A signal in which the "0"s and "1"s of the above are inverted and the output based on equations (46) to (48) output from anti-windup integrator 411 are input, and these are multiplied together and output to third summing point 421.

[0176] A speed command from the unwindup integrator 411 and a speed command in the same direction as the control cycle one step before from the position feedback invalidation unit 412 are input to the third summing point 421. Here, due to the presence of the signal inverting unit 430, either the third multiplication point 450 or the fourth multiplication point 451 will be multiplied by "0".

[0177] Therefore, at the third summing point 421, only one of the speed command from the unti-windup integrator 411 and the speed command in the same direction as the control cycle one step before from the position feedback disabling unit 412 is output to the second output point 341, and the speed command is output via the second output point 341 to the proportional valve control unit 311, the on / off valve control unit 312, and the slip symptom detection unit 313.

[0178] Therefore, when a signal of "1", corresponding to detection of an excess of the command speed, is output from speed command excess detection unit 314, a speed command in the same direction as that in the control cycle one step before from position feedback invalidation unit 412 is output as a speed command to proportional valve control unit 311, ON-OFF valve control unit 312, and slip sign detection unit 313. On the other hand, when a signal of "0", corresponding to no detection of an excess of the command speed, is output from speed command excess detection unit 314, a speed command from unti-windup integrator 411 is output as a speed command to proportional valve control unit 311, ON-OFF valve control unit 312, and slip sign detection unit 313.

[0179] As a result, as already mentioned above, when slip motion occurs, continuous application of feedback to the target position is prevented, and oscillatory response divergence can be prevented.

[0180] As described above, in the pneumatic actuator control device 100E according to the fifth configuration example, the position controller 410 includes a position feedback disabling unit 412, and further the speed controller 310 includes a speed command excess detection unit 314. As a result, the response divergence seen in the fourth configuration example can be effectively suppressed, and highly stable position control can be achieved.

[0181] Furthermore, in the fifth configuration example, a position control unit 400 controls the position of the cylinder 31 by feedback control with respect to a target position, and includes: a position control unit 400 that outputs a speed command corresponding to the position deviation; and a speed command excess detection unit 314 that performs a predetermined calculation based on the speed command output from the position control unit 400 and the moving speed of the piston 32, and detects whether the speed command exceeds a predetermined speed excess judgment threshold. When the speed command excess detection unit 314 detects that the speed command exceeds the speed excess judgment threshold, the position control unit 400 continues to output a speed command at a constant speed that is smaller in magnitude and in the same direction as the speed command one step before the detection.

[0182] When it is detected that the speed command exceeds the overspeed determination threshold in this way, feedback control is disabled by continuing to output a constant speed command with a small magnitude in the same direction as the speed command one step before detection. By disabling feedback control, it is possible to prevent response divergence caused by continuing to apply feedback to the target position when the speed command excess detection unit 314 detects that the speed command exceeds a predetermined overspeed determination threshold.

[0183] In addition, in the fifth configuration example, the position control unit 400 executes PI control, and when the speed command excess detection unit 314 detects that the speed has exceeded the speed excess determination threshold, the position control unit 400 sets the integral compensation term to zero, and after the integral compensation term is set to zero, when the speed of the piston 32 falls below a predetermined speed, the position control unit 400 resumes outputting the speed command.

[0184] For this reason, position control unit 400 executes PI control, and when speed command excess detection unit 314 detects that the speed has exceeded the speed excess determination threshold, it sets the integral compensation term to zero. As a result, speed control unit 300 does not inherit the integral value before the command speed was exceeded, and it is possible to prevent unstable behavior after the output of a speed command corresponding to the position deviation is resumed and the position feedback function is restored. [Explanation of symbols]

[0185] 1...vehicle, 2...car body, 10...bogie, 11...bogie frame, 11a...bracket, 12...wheel set, 12a...wheel, 12b...axle, 13...axle box, 14...axle box support device, 15...axle spring, 16...axle damper, 17...air spring, 20...automatic height adjustment device, 21...height adjustment valve, 23...height adjustment rod, 24...air reservoir, 30...pneumatic actuator, 31...cylinder, 31a...bottom side inner cylinder portion (corresponding to one chamber), 31 b... Rod side inner cylinder portion (corresponding to the other chamber), 32... Piston, 32a... Partition wall, 32b... Piston rod, 100, 100A, 100B, 100C, 100D, 100E... Pneumatic actuator control device, 110... High-pressure tank, 120... Air supply adjustment valve, 130... Directional switching valve, 140... Exhaust cutoff valve, 150... Reset valve, 160... Computer, 170... Microcomputer, 180... Proportional valve control section , 190...Switching valve control section, 195...DA converter, 200...Feedback control section, 300...Speed ​​control section, 310...Speed ​​controller, 311...Proportional valve control section, 312...ON / OFF valve control section, 313...Slip symptom detection section, 314...Speed ​​command excess detection section, 320...Controlled object, 330...Speed ​​calculation section, 340...First draw-out point, 341...Second draw-out point, 342...Third draw-out point, 343...Fourth draw-out point, 350...First Summation point, 361...first multiplication point, 362...second multiplication point, 400...position control unit, 410...position controller, 411...unti-windup integrator, 412...position feedback invalidation unit, 420...second summation point, 421...third summation point, 430...signal inversion unit, 440...fourth extraction point, 441...fifth extraction point, 450...third multiplication point, 451...fourth multiplication point, P1 to P5, P7...pipe lines, P6, P8...atmospheric open pipe lines

Claims

1. A pneumatic actuator control device controls the drive of a pneumatic actuator that changes the length of a height adjustment rod to adjust the height of a railway vehicle body, the pneumatic actuator having a cylinder, a piston, and a piston rod, a high-pressure tank for supplying compressed air; an air supply adjustment valve for adjusting the flow rate of the compressed air supplied from the high-pressure tank; a proportional valve control unit that controls the opening degree of the air supply adjustment valve; a directional control valve that alternately supplies and exhausts the compressed air, the flow rate of which is adjusted by the air supply adjustment valve, to one chamber and the other chamber isolated by the piston in the cylinder, the directional control valve being configured to be selectively switchable between a first state in which air can be supplied to the one chamber and exhausted from the other chamber, and a second state in which air can be supplied to the other chamber and exhausted from the one chamber; a directional control valve control unit that switches the directional control valve between the first state and the second state; A pneumatic actuator control device comprising:

2. 2. The pneumatic actuator control device according to claim 1, an exhaust shutoff valve that can shut off exhaust gas through the directional control valve; an exhaust cutoff valve control unit that controls exhaust cutoff by the exhaust cutoff valve; a main control unit that controls the operation of the intake adjustment valve, the directional control valve, and the exhaust cutoff valve by sending control signals to the proportional valve control unit, the directional control valve control unit, and the exhaust cutoff valve control unit, thereby controlling the position of the piston in the cylinder; The pneumatic actuator control device further comprises:

3. 2. The pneumatic actuator control device according to claim 1, a reset valve that releases pressure in the cylinder when the piston reaches one stroke end of the cylinder and is moved toward the other stroke end; a reset valve control unit that controls the release of pressure in the cylinder by the reset valve; Furthermore, The directional control valve control unit switches the position of the directional control valve after the pressure in the cylinder is released. A pneumatic actuator control device characterized by:

4. 3. The pneumatic actuator control device according to claim 2, a position control unit that controls the position of the piston in the cylinder by feedback control with respect to a target position, and outputs a speed command corresponding to a position deviation; a speed control unit that controls a moving speed of the piston by feedback control with respect to a target speed indicated by the speed command output by the position control unit; a speed command excess detection unit that performs a predetermined calculation based on the speed command output from the position control unit and the moving speed of the piston, and detects whether the speed command exceeds a predetermined speed excess determination threshold value, When the speed command excess detection unit detects that the speed command exceeds the speed excess determination threshold, the position control unit performs control to continue outputting the speed command in the same direction as the speed command one step before the detection and at a constant speed with a small magnitude. A pneumatic actuator control device characterized by:

5. 5. The pneumatic actuator control device according to claim 4, The position control unit performs PI control, When the speed command excess detection unit detects that the speed exceeds the speed excess determination threshold, the integral compensation term is set to zero; After the integral compensation term is set to zero, when the speed of the piston becomes equal to or lower than the predetermined speed, the output of the speed command is resumed. A pneumatic actuator control device characterized by:

6. A method for controlling the driving of a pneumatic actuator that changes the length of a height adjustment rod for adjusting the height of a railcar body, the pneumatic actuator having a cylinder, a piston, and a piston rod, comprising: a high-pressure tank for supplying compressed air; an air supply adjustment valve for adjusting the flow rate of the compressed air supplied from the high-pressure tank; a directional control valve that alternately supplies and exhausts the compressed air, the flow rate of which is adjusted by the air supply adjustment valve, to one chamber and the other chamber isolated by the piston in the cylinder, the directional control valve being configured to be selectively switchable between a position where air can be supplied to the one chamber and exhausted from the other chamber, and a position where air can be supplied to the other chamber and exhausted from the one chamber; A method for controlling a pneumatic actuator of a pneumatic actuator control device comprising: Controlling the opening of the air supply adjustment valve; Switching the position of the directional control valve A method for controlling a pneumatic actuator.

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