JPH05321904A - Drive controller in pneumatic cylinder - Google Patents

Abstract

PURPOSE:To smoothly drive a pneumatic cylinder and improve the stop accuracy of a piston at an intermediate position. CONSTITUTION:The position of the piston 22 of a rodless cylinder 21 is detected by a position detector 31. A control computer 34 controls a solenoid valve controlling circuit 36 based on the piston position information obtained from the position detector 31. The solenoid valve controlling circuit 36 performs the PWM control of solenoid valves 25, 26, 27, 28, and 30 based on the direction of the control computer 34. The solenoid valve 25 controls the supply of pressured air to the pressure applying chamber 21a of the rodless cylinder 21, and the solenoid valve 27 controls the supply of pressured air to the pressure applying chamber 21b of the rodless cylinder 21 from a pressured air source 24. The solenoid valves 26 and 28 are used for air exhaust, and the solenoid valve 30 controls the communication and cut off between the pressure applying chambers 21a and 21b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control method for a pneumatic cylinder.

[0002]

2. Description of the Related Art Pneumatic cylinders have a simple structure,
Although it has the advantage of being inexpensive, it has a large impact at the time of starting and stopping, and it is difficult to perform intermediate stop control. Therefore, it cannot be used for the transportation of delicate items, the transportation of precision equipment, etc., and the intermediate stop positioning, and it has been limited to the transportation of relatively rough and sturdy articles for the full stroke transportation.

As the intermediate stop control, "Learning position control of pneumatic cylinder", published in Vol. 53, No. 496, March 1987 issue of The Opportunity Society of Japan, and 198.
There is "Pulse Width Modulation Speed Control of Pneumatic Cylinder" published in Nov. 3, 2013, Vo14, No7, but all of them are not practical because they are complicated and lack smoothness.

An object of the present invention is to provide a drive control method in a pneumatic cylinder that can smoothly achieve an intermediate position stop.

[0005]

Therefore, according to the first aspect of the invention, the moving region from the starting position of the piston of the pneumatic cylinder to the target stop position is divided into a drive control region and a stop control region, and the piston is set in the drive control region. Position and speed at each position, and fuzzy inference determines the valve opening of the proportional control valve for air supply control so that the detected speed approaches the ideal speed preset for each position. When moving from the region to the stop control region, air supply control is performed so that the speed is constant, only the piston position is detected in the stop control region, and when the piston reaches a predetermined position before the target stop position. I tried to brake the piston.

According to the second aspect of the invention, the moving area from the starting position of the piston of the rodless cylinder to the target stopping position is divided into a drive control area and a stop control area, and the position of the piston is detected in the drive control area and The duty ratio of the repetitive pulse of the on / off valve for air supply control is determined by fuzzy reasoning for each position, and the air supply control is performed so that the speed is constant when the drive control region is changed to the stop control region.

According to the third aspect of the invention, when the piston of the rodless cylinder is started, air pressure is applied to the piston in a direction opposite to the direction of advance in advance, and the piston is actuated under this back pressure application state. Was started and the pressure air supply time for applying the back pressure was determined by fuzzy reasoning.

[0008]

According to the first aspect of the invention, the piston position and the speed at each position in the drive control region are detected. The speed of the piston at this detected position is compared to the ideal speed,
The valve opening of the proportional control valve is determined by fuzzy reasoning so that the difference between the detected speed and the ideal speed approaches zero. When the position of the piston shifts from the drive control region to the stop control region, the piston is controlled to a constant low speed, and only the position of the piston is detected in the stop control region. When it is detected that the piston has arrived before the target stop position based on this position detection, sliding contact braking is applied to the piston rod.

In the second invention, only the position of the piston of the rodless cylinder is detected, and the on-off valve is subjected to variable control of the duty ratio of the repetitive pulse by fuzzy reasoning based on only this position detection. When the position of the piston shifts from the drive control region to the stop control region, the piston is controlled at a constant low speed.

In the third aspect of the invention, when the piston is started, the air pressure is applied in the direction opposite to the direction in which the piston moves. This pressure air supply time, that is, the magnitude of the back pressure is determined by fuzzy reasoning, and the piston is activated under this back pressure application state.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the first invention will be described below with reference to FIGS. As shown in FIG. 1, a pair of pressurizing chambers 1 is formed in the pneumatic cylinder 1 by a piston 2.
It is divided into a and 1b, and the piston rod 2a projects from one pressurizing chamber 1b. A pneumatic brake 3 is built in the pressurizing chamber 1b so that the piston rod 2a can be braked by the sliding contact action of the pneumatic brake 3.

From the pressure air supply source 4 to both pressure chambers 1a, 1b
The pressure air is supplied to the air supply solenoid valve 5 and the electropneumatic proportional control valve 6, and the electropneumatic proportional control valve 6 and the pressurizing chamber 1a are supplied.
An exhaust electromagnetic on-off valve 7 is branched and connected to a flow path between the valve and the exhaust electromagnetic on-off valve 8 is also branched to a flow path between the electropneumatic proportional control valve 6 and the pressurizing chamber 1b. Has been done.

A position detector 9 is attached to the pneumatic cylinder 1, and the detected object 10 attached to the tip of the piston rod 2a is detected by the position detector 9.
As the position detector 9, a magnetostrictive vibration type absolute scale utilizing the Wiedemann effect is used.

The output signal from the position detector 9 is taken into the control computer 12 via the A / D converter 11.
A time counter 13 is connected to the control computer C, and the control computer 12 grasps the position of the object 10 to be detected, that is, the position of the piston 2 based on the position detection information obtained from the position detector 9, and detects the position detection information. And the speed of the piston 2 is calculated based on the time information obtained from the time counter 13. The control computer 12 controls the excitation / demagnetization of the electromagnetic on-off valves 5, 7, 8 and the pneumatic brake 3 based on the detected position and the detected speed of the piston 2, and opens the electropneumatic proportional control valve 6 via the proportional valve controller 14. Control the degree. The proportional valve controller 14 is used to obtain a dither signal effect for enhancing the responsiveness of the electropneumatic proportional control valve 6.

The graph of FIG. 6 is for performing fuzzy inference.
Represents the membership function for the piston position Y of
Function y₁, Y₂, Y₃, Y_Four, Y_Five, Y₆, Y₇, Y₈
Is the piston 2 and the target stop position X_eFuzzy representing the distance from
I set Y₁, Y₂, Y₃, Y _Four, Y_Five, Y₆, Y₇, Y
₈It is a membership function set in correspondence with. F
Azzy set Y_i(I = 1 to 8) is a collection of the following distances
It is Ri. Y₁= Target position X_e<Too far> distance Y₂= Target position X_e<Quite far> distance Y₃= Target position X_e<Far> distance from Y_Four= Target position X_eTo <normal> Y_Five= Target position X_e<a little closer> Y₆= Target position X_e<Close> to Y₇= Target position X_e<Quite close> distance Y₈= Target position X_e<Too close> distance The graph in Fig. 7 shows the piston 2 for fuzzy reasoning.
Position and ideal speed V ₀Membership regarding relationship with
Function v, the function v_1j(J = 1 to 4), v_2j(J = 1
~ 4), v_3j(J = 2 to 5), v_4j(J = 2 to 5), v
_5j(J = 2 to 5), v_6j(J = 2 to 6), v_7j(J = 2
~ 6), v_8j(J = 2 to 6) is the ideal speed V of the piston 2.
₀Fuzzy set V_ijCorresponding to (i = 1 to 8)
It is a set membership function. Fuzzy set V
_ijIs a set of distances as follows. V_i1= <Quite slow> ideal speed V_i2= <Slow> ideal speed V_i3= <Suitable> ideal speed V_i4= <Fast> ideal speed V_i5= <Very fast> Ideal speed V_i6= <Too fast> Ideal speed Membership function y in Figs. 6 and 7_i, V_ijIs experimental
Both membership functions y_i, V_ij
An ideal velocity curve C obtained by fuzzy inference based on ₂Figure 2
Is shown in. Position x_FiveRepresents the initial position of piston 2.
And this initial position x₁And position (X_e-L₁Between)
The area is set as a drive control area, and the position (Xe-L₁)
And target stop position X_eThe area between and is the stop control area
Is set. Drive control area [x₁, X_e-L₁] From stop
Stop control area [X_e-L₁, X_e] When moving to
The speed of the ton 2 is controlled to be constant at a low speed, and the position (X_e-L
₂In (), the pneumatic brake 3 is activated.

Fuzzy inference is performed as follows. When the distance Y when the position of the piston 2 is x is Y (x), fuzzy sets Y _i = Y ₃ , Y ₄ of the distance Y (x) are obtained as shown in FIG. 6, and the fuzzy set Y is obtained. ₃ ,
The fuzzy set V _ij giving the ideal velocity corresponding to Y ₄ is V
₃₄ and V ₄₃ . The grades in the fuzzy sets Y ₃ and Y ₄ are α ₁ and α ₂ , and the area area of the grade α ₁ or less in the fuzzy set V ₃₄ is hatched in FIG. 7, and the area of the grade α ₂ or less in the fuzzy set V ₄₃ is shown. Areas are indicated by hatching in FIG. FIG. 8 shows a combined area of both hatched areas, and an ideal velocity V ₀ (x) corresponding to the area center of gravity of the combined area is obtained for each position x of the piston 2.

The flowcharts of FIGS. 9 to 11 show a stop positioning control program, and the control computer 12 follows the stop positioning control program to open the electromagnetic on-off valves 5, 5.
7, 8, the electro-pneumatic proportional control valve 6 and the pneumatic brake 3 are excited and demagnetized. The control rules R _{1 to} R ₆ for fuzzy inference used for this control are set as follows. R ₁ = <If the speed V is much slower than the ideal speed V ₀ , the electropneumatic proportional control valve 6 is normally opened> R ₂ = <If the speed V is slower than the ideal speed V ₀ ,
Open the electro-pneumatic proportional control valve 6 a little> R ₃ = <If the speed V is appropriate as the ideal speed V ₀ ,
Do not change the opening / closing of the electropneumatic proportional control valve 6> R ₄ = <If the speed V is a little faster than the ideal speed V ₀ , close the electropneumatic proportional control valve 6 a little> R ₅ = <If the speed V is If the speed V is considerably faster than the ideal speed V ₀ , the electropneumatic proportional control valve 6 is normally closed. R ₆ = <If the speed V is faster than the ideal speed V ₀ , the electropneumatic proportional control valve 6 is closed greatly. The curve C ₁ of the graph of FIG. 3 is a characteristic curve showing the relationship between the valve opening of the electropneumatic proportional control valve 6 and the speed of the piston 2. As can be seen from the characteristic curve C ₁ , the piston speed is linearly proportional when the valve opening is in the range of 10% to 30%. Therefore, in this embodiment, the valve opening range of the electropneumatic proportional control valve 6 is set to 10% to 30%.
Then, the control rule is set based on the characteristic relationship indicated by the curve C ₁ .

The graph of FIG. 4 shows a difference ΔV between the detected speed V (x) and the ideal speed V ₀ (x) at the detected position x of the piston 2 for performing fuzzy inference based on the control rule.
Represents a membership function with respect to the functions Δv ₁ and Δv
₂ , Δv ₃ , Δv ₄ , Δv ₅ , and Δv ₆ are fuzzy sets ΔV ₁ , ΔV ₂ , ΔV ₃ , ΔV ₄ , and Δ with respect to the speed difference ΔV.
It is a membership function set corresponding to V ₅ and ΔV ₆ . The fuzzy set ΔV _k (k = 1 to 6) is the following set of speed differences. ΔV ₁ = speed considerably slower than ideal speed V ₀ ΔV ₂ = speed slower than ideal speed V ₀ ΔV ₃ = speed appropriate as ideal speed V ₀ ΔV ₄ = speed faster than ideal speed V ₀ ΔV ₅ = Vastly faster than the ideal speed V ₀ ΔV ₆ = Very faster than the ideal speed V ₀ The graph of FIG. 5 shows the electropneumatic proportional control valve 6 for performing fuzzy inference based on the control rule. A membership function relating to the valve opening change amount Θ is expressed as functions θ ₁ , θ ₂ , θ ₃ ,
θ ₄ , θ ₅ , and θ ₆ are membership functions set corresponding to the fuzzy sets Θ ₁ , Θ ₂ , Θ ₃ , Θ ₄ , Θ ₅ , and Θ ₆ regarding the valve opening change amount Θ. Fuzzy set Θ
_k (k = 1 to 6) is a set of the following valve opening change amounts. Θ ₁ = Valve opening change amount of about <normal opening> Θ ₂ = Valve opening change amount of about <Open> Θ ₃ = Valve opening change amount of <zero> About Θ ₄ = <Slight closing> Valve opening change amount Θ ₅ = <normally closed> valve opening change amount Θ ₆ = <largely closed> valve opening change amount Below, in the stop positioning control program shown in the flowcharts of FIGS. 9 to 11. Based on this, the stop positioning control of the pneumatic cylinder 1 will be described.

The control computer 12 operates the pneumatic brake 3 in advance, and the piston 2 is in the lockup state. The control computer 12 determines the initial position x of the piston 2.
₁ is sampled and the driving direction of the piston 2 is grasped based on the comparison with the target stop position X _e . The target stop position X _e in the state of FIG. 1 is on the pressurizing chamber 1b side, and the piston 2 is driven to the pressurizing chamber 1b side.

Next, the control computer 12 causes the exhaust power
The magnetic on-off valves 7 and 8 are excited for a predetermined time. Excitation for this predetermined time
Both pressurizing chambers 1a and 1b become atmospheric pressure due to
1a and 1b are in pressure equilibrium. Electromagnetic opening and closing for exhaust
After energizing the valves 7 and 8 for a predetermined time, the control computer 12 opens the eyes.
Standard stop position X_eAnd initial position x₁Distance Y₀And calculate
This calculated distance Y₀Depending on the
In addition to controlling the air direction, set the solenoid valve 5 for air supply to a predetermined value.
Time t (Y₀) Energize. This predetermined time t (Y ₀) Decision
The fuzzy inference is performed beforehand to establish the control
The computer 12 uses the function t (Y₀)as well as
Detection distance Y₀Based on the predetermined time t (Y ₀) Is calculated
It This predetermined time t (Y₀) Pressurization chamber 1a by excitation
(Or 1b) is pressurized. After this pressurization, the electromagnetic opening for exhaust is performed.
The closing valve 8 (or 7) is excited, and the pressurizing chamber 1b (or 1a)
Is released to the atmosphere. Then, the pneumatic brake 3 stops operating.
The piston is stopped and released from the braking action of the pneumatic brake 3.
Ton 2 starts driving without impact.

[0021] When the piston 2 is started driving, the control computer 12 is calculated based on the sampling of the position x of the piston 2 distance (X _e -x) = Y and speed V at that position, fuzzy as described above Detection position x by inference
The ideal speed V ₀ (x) at is calculated. Then, fuzzy inference is performed based on the ideal speed V ₀ (x) and the detected speed V (x).

This fuzzy inference is performed as follows. First, the belonging group ΔV _{k of the} fuzzy set ΔV (x) including the speed difference between the ideal speed V ₀ (x) and the detected speed V (x).
Is grasped. In the case of the distance Y (x) in FIGS. 6 and 7, the fuzzy sets ΔV _k are ΔV ₃ and ΔV ₄ , and the grades are β ₁ and β ₂ . The area of grade β ₁ or less in the membership function Δv ₃ corresponding to the velocity difference belonging group ΔV ₃ is shown by hatching in FIG. 5, and the region of grade β ₂ or less in the membership function Δv ₄ corresponding to the fuzzy set ΔV ₄ The area is hatched in FIG. The valve opening change amount Θ (x) corresponding to the center of gravity of the combined area of both hatched regions is calculated for the position x of the piston 2, and the valve opening change amount Θ (x) is changed.

By such fuzzy reasoning control, the speed of the piston 2 is made close to the ideal speed at each position, and the actual speed of the piston 2 in the drive control region [x ₅ , L ₁ ] is the ideal speed curve C _{1 in} FIG. Matches exactly.

When the piston 2 reaches the position L ₁ , the valve opening of the electropneumatic proportional control valve 6 is controlled to a constant value, and the speed of the piston 2 is controlled to a constant low speed. When the piston 2 reaches the position L ₂ in this low speed state, the pneumatic brake 3 is excited to brake the piston rod 2a, and at the same time, the electropneumatic proportional control valve 6 and the electromagnetic opening / closing valve 7 (or 8).
Is demagnetized and the piston 2 stops.

Air pressure 3.5 kgf / cm ² , moving distance of piston 2 (X _e -x ₅ ) = 150 mm, L ₁ = 4.2 mm, L
₂ = 140 μm, in an experiment with a load of 0 kg, the stopping accuracy was ± 230 μm, the average deviation was −41 μm, and the acceleration was 0.3.
Good results of G and operating time of 0.82 sec were obtained.

In this embodiment, the control computer 1
2 also calculates the ideal speed directly by fuzzy inference, but the expression of the ideal speed curve C ₂ obtained by the fuzzy inference is input to the control computer 12, and the ideal speed V is calculated.
The difference between ₀ and the detected speed V may be calculated.

Next, an embodiment embodying the second invention will be described with reference to FIGS. The rodless cylinder 21 shown in FIG. 12 is of the type disclosed in Japanese Patent Laid-Open No. 62-266206, and the piston 22 and the table 23 are connected by a special dustproof belt and a seal belt. Pressure air supply source 24 to piston 2
The pressure air is supplied to one of the pressurizing chambers 21a partitioned by 2 through the air supply electromagnetic on-off valve 25, and the flow path between the air supply electromagnetic on-off valve 25 and the pressure chamber 1a is provided. The exhaust electromagnetic on-off valve 26 is branched and connected. The other pressurizing chamber 21b
The compressed air is supplied to the air supply solenoid on-off valve 27, and the exhaust air solenoid on-off valve 28 is branched and connected to the flow path between the air supply solenoid on-off valve 27 and the pressurizing chamber 1b. There is. Both pressurizing chambers 21a and 21b are connected by a flow path 29, and an electromagnetic opening / closing valve 30 is interposed on the flow path 29.

The rodless cylinder 21 has a position detector 3
1 is attached, and the detected body 32 attached to the table 23 is detected by the position detector 31.
A magnetic proximity sensor is used as the position detector 31.

The output signal from the position detector 31 is taken into the control computer 34 via the counter 33, and the control computer 34, based on the position detection information obtained from the position detector 31, the position of the object 32 to be detected, that is, the piston. Two
Figure out the position of 2. The control computer 34 uses the D / A converter 35 and the electromagnetic opening / closing valve control circuit 36 based on the detected position of the piston 22 to open the electromagnetic opening / closing valves 25 to 28, 30.
Control the demagnetization of.

The electromagnetic on-off valve control circuit 36 is a pulse generation circuit for pulse wide modulation (PWM) control, and as shown in FIG. 20, a pulse signal is generated based on a comparison between the reference triangular wave C ₃ and the DC voltage C _4. Output C ₅ .

21 and 22 show a stop positioning control program, which is a control computer 34.
Performs the excitation / demagnetization control of the solenoid on-off valves 25-28, 30 in accordance with this stop positioning control program. The control rules R _{11 to} R ₁₅ for fuzzy inference used for this control are set as follows. R ₁₁ = <If the piston position x is far from the target stop position X _e , accelerate> R ₁₂ = <If the piston position x is close to the target stop position X _e , decelerate> R ₁₃ = <If the piston Position x is starting area [X _s , L ₃ ]
If it is, reduce the acceleration> R ₁₄ = <If the piston position x is the stop preparation region [L ₄ , X
_e ], decrease the deceleration> R ₁₅ = <make the acceleration change as smooth as possible> X _s represents the initial position, and the initial position X _s and the target stop position X _e are The control computer 3 is preset by the input device 34a.
It is entered in 4.

The control rule R ₁₅ is set so that the average speed of the piston 22 is as large as possible and the change in acceleration does not exceed a predetermined upper limit. The curve C _{7 in} FIG. 18 is an ideal speed curve of the piston 22 representing the control rule R ₁₅ .

13 (a), 14 (a) and 14
The graphs of (a), FIG. 15 (a) and FIG. 16 (a) are controllable.
Rule R₁₁~ R₁₄For making fuzzy inference based on
Membership function related to detection position x of piston 22
Represents the function f₁, F₂, F₃, F_FourIs in the piston position
Related fuzzy set F₁, F₂, F₃, F_FourIn response to
It is a set membership function. Fuzzy set F
_m(M = 1 to 4) is a collection of the following positions. F₁= Target stop position X_e<Far> position from F₂= Target stop position X_ePosition <close> to F₃= <Starting area [X_s, X₁] Position F_Four= <Stop preparation area [X₂, X_e] Position> FIG. 13 (b), FIG. 14 (b), FIG. 14 (b), FIG.
The graphs of (b) and FIG. 16 (b) show the control rule R.₁₁~ R₁₄
Of the piston 22 for performing fuzzy inference based on
Show membership function for acceleration at position x
And the function g₁, G ₂, G₃, G_FourIs the acceleration
J-set G₁, G₂, G₃, G_FourWas set according to
It is a membership function. Fuzzy set G_m(M = 1
4) are the following acceleration groups. G₁= <Accelerate> G₂= <Decelerate> G₃= <Reduce acceleration> G_Four= <Reduce deceleration> Curve C in the graph of FIG.₆Is the control rule R₁₅Based on
Position x and acceleration of piston 22 for fuzzy reasoning
The relationship between the acceleration and deceleration is fixed.
Position is X₃, X_FourIt is near. Acceleration curve C₆Is Figure 1
Ideal speed curve C of graph 8₇Piston position represented by
And piston speed calculated from the relationship between
Indicates the relationship with ton acceleration.

A curve C _{8 in} the graph of FIG. 23 represents the relationship between the duty ratio of the solenoid valves 25 and 27 for supplying air and the piston speed, and has a substantially linear proportional relationship in the range of 17% to 21%. The curve C _{9 in} the graph of FIG. 19 is the curve C
The relationship between the piston position and the DC voltage E obtained from the relationship between the piston position and the piston speed represented by the curve C ₇ based on the characteristic relationship represented by ₈ . That is, the curve C ₉ is a control formula for performing the fuzzy inference based on the control rule R ₁₅ , and the stop position control in the rodless cylinder 21 is performed by the fuzzy inference only from the detection of the piston position.

The stop positioning control of the rodless cylinder 21 will be described below based on the stop positioning control program shown in the flow charts of FIGS. 21 and 22. In this embodiment the initial position of the piston 22 to the left end position X _s of the pressure chamber 21a side, a case of driving the piston 22 to the pressurizing chamber 21b side.

The control computer 34 samples the position x of the piston 22, and this detected position x is the initial position X _s.
If not, the solenoid valves 27, 26 are excited. The pressurization chamber 21a is opened to the atmosphere by exciting the electromagnetic opening / closing valve 26,
The pressurization chamber 21b is pressurized by the excitation of the electromagnetic opening / closing valve 27. As a result, the piston 22 moves toward the initial position X _s , and when the piston 22 reaches the initial position X _s , the electromagnetic opening / closing valves 27 and 26 are demagnetized.

Next, the control computer 34 pulse-excites the air supply electromagnetic on-off valve 25 and the exhaust electromagnetic on-off valve 28 for a predetermined time. The electromagnetic on-off valves 25 and 28 are repeatedly opened and closed at high speed by the pulse excitation for the predetermined time to pressurize the pressurizing chamber 21a and open the pressurizing chamber 21b to the atmosphere. Due to this opening and closing, the pressure air vibrates, and the influence of the static friction force of the piston 22 can be canceled. As a result, the rapid rise of the piston 22 is suppressed. The application of such a pulse voltage is called a dither signal and contributes to the start of piston drive without impact.

A curve C _{10 in} FIG. 24 is a solenoid valve 25 for air supply.
5 shows a piston velocity curve at the time of starting when a dither signal is applied to only A curve C ₁₁ is a pulse duty ratio curve which becomes a dither signal. Since the reference triangular wave C ₃ is 10 msec, the pulse frequency of the dither signal is 100 Hz. The static frictional force of the piston 22 in the rodless cylinder 21 as in the present embodiment is larger than that in the cylinder with a rod, and when a dither signal of about 100 Hz is applied only to the on / off valve 25 for air supply, the piston speed rises sharply at startup. The phenomenon cannot be suppressed sufficiently.

However, in this embodiment, since the dither signal is also applied to the electromagnetic opening / closing valve 28 for exhaust, pulse driving of both the electromagnetic opening / closing valves 25 and 28 brings about a synergistic effect, and the frequency of the pressure air is greatly increased. Increase. A curve C _{12 in} FIG. 25 represents a piston velocity curve at the time of starting when a dither signal is applied to both the electromagnetic opening / closing valves 25 and 28. As is clear from the curve C _12, the rapid rise of the piston speed at the time of starting is sufficiently suppressed.

When the piston 22 is driven, the control computer 34 performs fuzzy inference according to the control rules R _{11 to} R ₁₅ based on the sampling of the position x of the piston 22. The DC applied voltage E (x) corresponding to the detection position x is calculated and output by this fuzzy inference, and the air supply solenoid on-off valve 25 is subjected to PWM control. Rodless cylinder 2
Irregular jerking motion occurs in 1, but
It is difficult to finely adjust the piston speed for such an irregular phenomenon due to the response delay due to the compressibility of air, and it is expected that a better result should be obtained by ignoring the instantaneous speed fluctuation. Therefore, this PWM control is performed only by detecting the piston position as an input condition.

Further, since the change in the acceleration of the piston 22 is suppressed to a predetermined upper limit or less by the control rule R ₁₅ , the operation of the piston 22 is smooth. Moreover, the control rule R ₁₅ includes the speedup of the average speed as much as possible, and the operation time of the piston 22 from the starting position to the stopping position is shortened as much as possible.

When the piston 22 is in the stop control region [X _e −
L ₂ , X _e ], the control shifts to a constant low speed control as in the case of the first embodiment. Then, when the piston 22 reaches the position (X _e −L ₃ ) (L ₂ > L ₃ ), the electromagnetic opening / closing valve 30 is subjected to the PWM control, and both pressurizing chambers 21a and 21b.
Communicate with each other. Due to this communication, the pressure air also flows into the pressurizing chamber 21b, and the piston 22 is buffered. This cushioning degree can be optimally set by adjusting the duty ratio, and the piston 22 decelerates to start fine speed driving.

The piston 2 driven at a very low speed is moved to the position (X _e -L
₄ ) When (L ₃ > L ₄ ) is reached, solenoid valve for air supply 2
5 is demagnetized, and the exhaust electromagnetic on-off valve 28 is demagnetized. That is, the air in the two pressurizing chambers 21a and 21b is confined while the two pressurizing chambers 21a and 21b are in communication with each other. Due to this air confinement, pressure fluctuations in both pressurizing chambers 21a and 21b are eliminated, and the piston 22 driven at a slow speed is stopped.

According to this air confinement method, the piston moving distance from a constant low speed state to the stop does not depend on the piston position, so that the low speed constant, the air pressure constant and the passage cross-sectional area of the flow passage 29 are constant. For example, there is an advantage that the piston movement distance from the low speed state to the stop is substantially constant.

When the piston 22 stops, the control computer 34 samples the stop position x ₀ of the piston 22 and determines the difference (x) between the actual stop position x ₀ and the target stop position X _e.
0 −X _e ) = ΔX _e is calculated. This difference ΔX _e is incorporated in the deceleration start position (X _e −L ₃ ) due to the buffering action in the stop control region during the next piston drive. That is,
The previous value L ₃ is changed to (L ₃ + ΔX _e ). This is the adoption of a learning control method that corrects the piston stop position. The rodless cylinder 21 has a large speed change at the time of shifting from the drive control to the stop control when the cylinder state changes due to a temperature change or the like, and the PWM control of the electromagnetic opening / closing valve 30 may not be able to suppress the fluctuation of the piston stop position. However, this problem is solved by adopting the learning control method.

Air pressure 1.5 kgf / cm ² , moving distance of piston 22 (X _e -x ₁ ) = 300 mm, X ₁ = 5 mm, X ₂
= 150 mm, X ₃ = 91 mm, X ₄ = 91 mm, no load
In the experiment in the case of kg, stopping accuracy ± 447, average deviation −
Good results of 1, acceleration 1.2G, operation time 1.2sec were obtained, and it was confirmed that the combination method of PWM control and fuzzy control is effective for the rodless cylinder 21 without the sliding contact braking mechanism. It

Next, an embodiment in which the third invention is embodied in a rodless cylinder of a type in which a table follows a piston by utilizing a magnet attractive force will be described with reference to FIGS.

The rodless cylinder 37 shown in FIG.
The table 39 on the guide rail 38 is of a type that follows the movement of the piston 40. The table 39 follows the movement of the piston 40 by the attraction force of the magnet 39a on the table 39 side and the magnet 40a on the piston 40 side. Since other configurations are similar to those of the second embodiment, the same members are designated by the same reference numerals and the description thereof will be omitted.

The flowcharts of FIGS. 30 to 32 show a low-impact drive control program and a stop positioning control program, and the control computer 34 performs the excitation / demagnetization control of the electromagnetic opening / closing valves 25-28, 30 in accordance with this control program. The control rules for fuzzy inference used for the stop positioning control are the same as R _{11 to} R ₁₅ of the second embodiment,
The duty ratio of the air supply electromagnetic on-off valves 25 and 27 is set in the range of 17% to 20%, which has a substantially linear proportional relationship with the piston speed.

The control rules R _{21 to} R ₂₃ for fuzzy inference used for low impact drive control are set as follows. R ₂₁ = <If the DC voltage value E (X _s, X _e ) is small, increase the excitation time> R ₂₂ = <If the DC voltage value E (X _s, X _e ) is normal, the excitation time is normal R ₂₃ = <If the DC voltage value E (X _s, X _e ) is large, shorten the excitation time> The DC voltage value E (X _s, X _e ) is the initial position X of the piston 40.
It is a DC voltage value for determining the duty ratio at the time of starting the piston, which is determined from _s and the target stop position X _e .

27 (a), 28 (a) and 29
The graph of (a) represents the membership function for the DC voltage value E (X _s, X _e ) for performing fuzzy inference based on the control rules R _{21 to} R ₂₃ , and the functions e ₁ , e ₂ , e ₃ are A fuzzy set E _{1 for} the DC voltage value E (X _s, X _e ),
It is a membership function set corresponding to E ₂ and E ₃ . The fuzzy set E _n (n = 1 to 3) is the following set of DC voltage values. E ₁ = <small> DC voltage value E ₂ = <normal> DC voltage value E ₃ = <large> DC voltage value The graphs of FIG. 27 (b), FIG. 28 (b) and FIG. 29 (b) are control rules. The membership functions relating to the excitation time of the air supply electromagnetic on-off valves 25 and 27 for performing fuzzy inference based on R _{21 to} R ₂₃ are represented, and the functions t ₁ , t ₂ and t ₃ are fuzzy sets T ₁ relating to the excitation time. , T ₂ , T ₃ are membership functions set in correspondence with each other. The fuzzy set T _n (n = 1 to 3) is the following set of excitation times. T ₁ = <long> excitation time T ₂ = <normal> excitation time T ₃ = <short> magnetizing time below, rod based on the low impact drive control program and stop positioning control program shown in the flowchart of FIGS. 30 32 The low impact drive and stop positioning control of the less cylinder 37 will be described. The initial position of the piston 40 in this embodiment as the left end position X _s of the pressure chamber 37a side, it is assumed that driving the piston 40 to the pressurizing chamber 37b side. The initial position X _s and the target stop position X _e are the input device 34.
It is input to the control computer 34 in advance by a. The movement control of the piston 40 to the initial position X _s is the same as that of the second embodiment.

After the piston 40 is placed at the initial position X _s , the control computer 34 excites the exhaust electromagnetic on-off valve 28 for a predetermined time. The electromagnetic opening / closing valve is opened by the excitation for the predetermined time, and the pressure chamber 40b becomes the atmospheric pressure.

After the pressure in the pressurizing chamber 40b becomes atmospheric pressure, the control computer 34 calculates the DC voltage value E (X _s, X _e ) at the time of start based on the initial position X _s and the target stop position X _e ,
Fuzzy inference for low impact driving is performed based on the calculated DC voltage value E (X _s, X _e ).

This fuzzy reasoning is performed as follows.
It First, the calculated DC voltage value E (X _s,X_e)
Azzy set E_nAnd the DC voltage value E (X
_s,X_e) Is calculated. Then fuzzy collection
E_nFuzzy set T of back pressure application time corresponding to_nGag
Grasp and back pressure application time T (X_s,X_e) Is the DC voltage value E
(X_s,X_e) Calculated based on the grade.

The control computer 34 energizes the air supply electromagnetic on-off valve 27 during the back pressure application time T (X _s, X _e ).
Due to this excitation, the pressure chamber 37b is pressurized and the piston 4
0 is applied with a pressure in the direction opposite to the traveling direction. The magnitude of this back pressure depends on the back pressure application time T (X _s, X _e ). Under such a back pressure application state, the supply air solenoid on-off valve 25 is repeatedly excited and demagnetized at the duty ratio corresponding to the DC voltage value E (X _s, X _e ) at the time of startup, and the exhaust solenoid on-off valve 25 is also activated. 28 is excited. Therefore, the piston 40 starts to be driven from the state where the reverse pressure is received in advance, and the sudden protrusion of the piston 40 is suppressed. The back pressure is large when the duty ratio is large, and is small when the duty ratio is small.

In an experiment in which the air pressure is 3.5 kgf / cm ² , the moving distance (X _e −X _s ) of the piston 40 = 150 mm, and the static friction force in the rodless cylinder 37 is 3.3 kgf, the stopping accuracy is ± 780 μm, the average is Good results are obtained, with a bias of +110 μm and a startup acceleration of 1.0 G.

[0057]

As described above in detail, the first aspect of the present invention detects the position of the piston and the speed at each position in the drive control area, and the detected speed approaches the ideal speed preset for each position. Fuzzy inference is used to determine the valve opening of the proportional control valve for air supply control, and the air supply control is performed so as to maintain a constant speed when moving from the drive control area to the stop control area. In addition to detecting only the position of, the brake is applied to the piston when the piston reaches a predetermined position before the target stop position, so smooth drive and high stopping accuracy are achieved despite simple control. The excellent effect of obtaining is obtained.

In the second invention, the position of the piston is detected in the drive control region, and the duty ratio of the repetitive pulse of the air supply control on-off valve is determined by fuzzy reasoning for each position, and the stop control is performed from the drive control region. Since the air supply control is performed so that the speed becomes constant when moving to the region, smooth control of the rodless cylinder and high stopping accuracy are achieved despite simple control and no sliding contact braking mechanism. The excellent effect of obtaining is obtained.

According to a third aspect of the present invention, when the piston of the rodless cylinder is started, air pressure is applied to the piston in a direction opposite to the advance direction thereof in advance, and the piston is actuated under this reverse pressure applied state. Was started and the pressure air supply time for applying the back pressure was determined by fuzzy reasoning.
The excellent effect that smooth driving at the time of starting can be achieved is exhibited.

[Brief description of drawings]

FIG. 1 is a combination diagram of a pneumatic cylinder and a control block circuit of an embodiment embodying the first invention.

FIG. 2 is a graph showing an ideal velocity curve of a piston.

FIG. 3 is a graph showing a relationship between a valve opening degree of an electropneumatic proportional control valve and a piston speed.

FIG. 4 is a graph showing a membership function of piston velocity.

FIG. 5 is a graph showing a membership function of valve opening.

FIG. 6 is a graph showing a membership function of piston position.

FIG. 7 is a graph showing a membership function of piston velocity for each piston position.

FIG. 8 is a graph showing a method of calculating an ideal speed with respect to a detection position.

FIG. 9 is a flowchart showing a stop positioning control program.

FIG. 10 is a flowchart showing a stop positioning control program.

FIG. 11 is a flowchart showing a stop positioning control program.

FIG. 12 is a combination diagram of a rodless cylinder and a control block circuit of an embodiment embodying the second invention.

13A is a graph showing a membership function of piston position, and FIG. 13B is a membership function of acceleration corresponding to FIG. 13A.

14A is a graph showing a membership function of a piston position, and FIG. 14B is a membership function of acceleration corresponding to FIG.

FIG. 15A is a graph showing a membership function of piston position, and FIG. 15B is a membership function of acceleration corresponding to FIG.

16A is a graph showing a membership function of a piston position, and FIG. 16B is a membership function of acceleration corresponding to FIG.

FIG. 17 is a graph showing the relationship between piston position and acceleration.

FIG. 18 is a graph showing the relationship between piston position and piston speed.

FIG. 19 is a graph showing the relationship between piston position and DC applied voltage.

FIG. 20 is a graph for explaining pulse generation used in PWM control.

FIG. 21 is a flowchart showing a stop positioning control program.

FIG. 22 is a flowchart showing a stop positioning control program.

FIG. 23 is a graph showing the relationship between duty ratio and piston speed.

FIG. 24 is a graph showing a piston speed curve under PWM control.

FIG. 25 is a graph showing a piston speed curve under PWM control.

FIG. 26 is a combination diagram of a rodless cylinder and a control block circuit of an embodiment embodying the third invention.

27A is a graph showing a membership function of a DC voltage value, and FIG. 27B is a membership function of an excitation time for applying a back pressure corresponding to FIG.

28A is a graph showing the membership function of the DC voltage value, and FIG. 28B is the membership function of the excitation time for applying the back pressure corresponding to FIG.

FIG. 29A is a graph showing a membership function of a DC voltage value, and FIG. 29B is a membership function of an excitation time for applying a back pressure corresponding to FIG.

FIG. 30 is a flowchart showing a low impact drive program and a stop positioning control program.

FIG. 31 is a flowchart showing a low impact drive program and a stop positioning control program.

FIG. 32 is a flowchart showing a low impact drive program and a stop positioning control program.

[Explanation of Codes] 1 ... Pneumatic cylinder, 2 ... Piston, 3 ... Pneumatic brake, 5 ... Air supply electromagnetic on-off valve, 6 ... Electropneumatic proportional control valve, 7,
8 ... Exhaust solenoid on-off valve, 9 ... Position detector, 12 ... Control computer, 21 ... Rodless cylinder, 22 ... Piston, 25, 27 ... Air supply solenoid on-off valve, 26, 28 ... Exhaust solenoid on-off valve, 29 ... Flow path, 30 ... Electromagnetic on-off valve, 31 ...
Position detector, 34 ... Control computer, 36 ... Electromagnetic on-off valve control circuit.

Claims (4)

[Claims] 1. A moving region from a starting position of a piston of a pneumatic cylinder to a target stop position is divided into a drive control region and a stop control region, and in the drive control region, a position of the piston and a velocity at each position are detected and detected. Fuzzy reasoning is used to determine the valve opening of the proportional valve for air supply control so that the speed approaches the ideal speed preset for each position, and the speed becomes constant when the drive control area is switched to the stop control area. In this way, the air supply control is performed so that only the piston position is detected in the stop control area, and when the piston reaches a predetermined position before the target stop position, the piston is braked. Method. 2. A moving region from a starting position of a piston of a rodless cylinder to a target stop position is divided into a drive control region and a stop control region, and the position of the piston is detected in the drive control region, and an air is detected at each position. The duty ratio of the repetitive pulse of the on-off valve for supply control is determined by fuzzy reasoning,
A drive control method in a pneumatic cylinder for performing air supply control so as to maintain a constant speed when shifting from the drive control area to the stop control area. 3. A drive control method for a pneumatic cylinder according to claim 2, wherein a fuzzy inference includes a control rule for providing a smooth acceleration change. 4. When the piston of the rodless cylinder is started, air pressure is applied to the piston in a direction opposite to the direction of advance in advance, and the piston is started under this reverse pressure applied state, A drive control method in a pneumatic cylinder that determines the pressure air supply time for applying counter pressure by fuzzy reasoning.