JPH0416647B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of controlling a fluid actuator used in construction machinery and the like.

[Prior Art] FIG. 8 is a system diagram showing a conventional hydraulic switching valve operation device, in which a hydraulic switching valve 5 that hydraulically controls a hydraulic motor 6 is located at switching positions 5a, 5b, and 5c. The switching position is operated by the hydraulic actuator 1 or the lever 1c, and the pressure oil is forced to be fed or removed from the displacement chamber 1a or 1b in the hydraulic actuator 1 by operating the switching valve 2 or 3. The structure is carried out by

The solenoids 2d and 3d for operating the switching valves 2 and 3 are manually turned on and off by operating a switch box 11 via electrical wiring.

The operation of the hydraulic switching valve operating device shown in FIG. 8 will be explained as follows.

The hydraulic motor 6 is driven by hydraulic power from the hydraulic switching valve 5, and the hydraulic switching valve 5 is in the switching position 5b.
, the flow of hydraulic power is closed and the operation of the hydraulic motor 6 is stopped.

On the other hand, when the hydraulic switching valve 5 is at the switching position 5a or 5c, hydraulic power is force-fed to one or the other of the hydraulic motors 6, driving the hydraulic motor 6 in one or the other direction.

Further, the hydraulic motor 6 drives a crane or the like (not shown).

The operation of the hydraulic switching valve 5 is performed by operating the hydraulic actuator 1 or manually operating the lever 1, and the operation of the hydraulic actuator 1 is as follows.

When the switching valves 2 and 3 are set to switching positions 2b and 3b, respectively, as shown,
Both displacement chambers 1a and 1b are each open to the reservoir 7, and the hydraulic actuator 1 is in a completely free state.

Therefore, in this state, when the driver operates the lever 1c from the driver's seat, the piston 1d in the hydraulic actuator 1 can be freely operated, and the operated piston 1d
operates the hydraulic switching valve 5.

In this way, by manually operating the lever 1c, the above switching position 5a, 5b or 5c can be arbitrarily selected, and the operation of the hydraulic actuator 1 is controlled by the driver from the driver's seat. The lever 1c can be operated while the user is in the room.

In addition, in the hydraulic actuator 1, the lever 1
A centering action is exerted on the piston 1d connected to the piston 1d by the springs 5e and 5f of the hydraulic switching valve 5.
Therefore, in a state where both the displacement chambers 1a and 1b are open to the reservoir 7 as described above,
When the driver releases the lever 1c, the hydraulic actuator 1 is in the illustrated position, and its switching position is set to 5b (neutral position).

For such manual operation, move the hydraulic actuator 1 away from the driver's seat, for example near the load of the hydraulic motor 6, while checking the movement of the load.
When remotely controlling the
The switch is manually operated to drive the solenoid 2d or 3d, and this drive operates the switching valve 2 or 3, and the operated switching valve 2 or 3 operates the hydraulic actuator 1.

Here, the operation of operating the hydraulic actuator 1 by operating the switching valve 2 or 3 is as follows.

When it is desired to fix the piston 1d in the hydraulic actuator 1 at an arbitrary position, the switching valves 2 and 3 are set to the switching position 2a and the switching position 3a, respectively.

When the switching positions of the switching valves 2 and 3 are set in this way, the pressure oil from the hydraulic source 4 is forced to be sent to both displacement chambers 1a and 1b, and the switching positions of the switching valves 2 and 3 to which the pressure oil is sent are Since check valves 2c and 3c are provided at the inlet portions, the movement of the piston 1d is fixed in the hydraulic actuator 1.

In this state, the displacement chambers 1a and 1b
Since oil pressure from the oil pressure source 4 is introduced to both of them, oil pressure is applied to the piston 1d from both sides of the piston 1d.

If only the switching valve 2 is set to the switching position 2b in such a state, the hydraulic pressure in the displacement chamber 1a is released to the reservoir 7 via the switching valve 2, so the piston 1d is moved to the hydraulic pressure in the displacement chamber 1b. Therefore, it is pressed downward in Fig. 8,
The pressure changes the switching position of the hydraulic switching valve 5 to 5.
Shift to side a.

Conversely, when the piston 1d is fixed and only the switching valve 3 is set to the switching position 3b, the hydraulic pressure in the displacement chamber 1b changes to the switching valve 3.
The hydraulic pressure in the displacement chamber 1a presses the piston 1d upward in FIG. is moved to the switching position 5c.

As mentioned above, the operation of the hydraulic switching valve operating device is as follows:
The operator operates the switching valve 2 or 3 using the manual switch, and determines whether the operation is appropriate or not while observing the movement of the load on the hydraulic motor 6.

However, since the remote control of the switching valve 2 or 3 shown in FIG. 8 is based on on/off operations using a manual switch, it is difficult to perform delicate operations.

For this reason, in such remote operation, a method is desired in which the position of the piston 1d is commanded for the operation and the operating position of the hydraulic switching valve 5 is feedback-controlled in response to the command.

Furthermore, it is desired that the feedback control method be inexpensive and durable, and the following methods are examples of such durable and inexpensive control methods.

When a deviation occurs between the command value and the feedback value, the hydraulic actuator is controlled in a direction to correct the deviation. The steps up to this point are normal feedback control.

In the control for correcting this deviation, the signal that controls the hydraulic actuator 1 is to force-feed pressure oil from the solenoid valve to the displacement chamber of the hydraulic actuator 1 as a single pulse, and the pulse application time duration of the single pulse is as follows: The values are based on experimental data that correspond to the fact that the deviation can be just corrected by the single pulse alone.

This means that the deviation is corrected each time it occurs by sending a single pulse of pressure oil to the hydraulic actuator 1 or sending a single pulse signal to its solenoid valve. .

In other words, from the transmission of a command signal instructing the position of the piston 1d, a feedback signal indicating the current position of the piston 1d is obtained, the difference between them and the resulting deviation are calculated, and the above-mentioned single pulse is calculated based on the deviation. Until the signal is sent, normal feedback control is in effect. Subsequently, a single pulse signal is transmitted to the solenoid valve according to the deviation result, and until the control of the hydraulic actuator 1 for the time of the transmission is completed, the control is in an open loop. .

If there is still a deviation in the control result of that time, the same single pulse control is performed based on the new deviation from the control result to converge the position of the piston 1d to the position specified by the command signal. let

Therefore, this method is inexpensive in that an inexpensive on/off solenoid valve can be used without using an expensive electro-hydraulic servo valve for proportional control.
Moreover, the on/off operation of the solenoid valve is different from normal solenoid valve control in which the solenoid valve is always turned on and off while changing the duty ratio depending on the magnitude of the deviation. That is, this control method uses an inexpensive solenoid valve, and the number of times the solenoid valve is turned on and off is extremely small, resulting in improved durability of the solenoid valve.

Furthermore, the application time of the single pulse signal in this control method is the sum of a fixed basic application time component that only starts the no-load hydraulic actuator 1 and an application time component that is proportional to the deviation. There is.

[Problems to be Solved by the Invention] In the above control method, the basic application time is a fixed constant time, which means that no matter in which direction the hydraulic actuator operates or in which region the hydraulic actuator operates. Even if the piston 1d operates, the condition is satisfied only when the conditions required for starting the piston 1d are the same.

However, as can be understood from the explanation in FIG. 8 above, the hydraulic actuator 1 controlled by the switching valves 2 and 3 has different operating directions and positions due to the centering springs 5e and 5f. The driving force at which the piston 1d starts to start is different. Furthermore, due to the initial setting of the centering springs 5e and 5f or the difference in their spring constants, the driving force at which the piston 1d starts to actuate at each operating position on the spring 5e or 5f side differs.

An object of the present invention is to provide a method for controlling a fluid actuator in which a single digital signal is used to control a fluid actuator whose activation force differs depending on the operating direction and each operating position of the piston 1d as described above. It's about doing.

[Means for Solving the Problems] A piston 1d is fitted into the cylinder 1e so as to be able to slide in the axial direction, and a switching valve is provided on one side and the other side of the piston in the axial direction. One displacement chamber 1a and the other displacement chamber 1b are provided to which pressurized fluid is selectively pumped or expelled through the pistons 2 and 3;
When no external force is acting on the piston, biasing forces are applied from one spring and the other spring for centering to set the piston to a neutral position, and the switching valve
A single pulse signal Vn of finite time width tn containing te
The correction application time width is a value proportional to the deviation Er between a detection signal detecting the position of the piston in the axial direction and a command signal instructing the position of the piston in the axial direction. In the above control, only the value immediately before the single pulse signal is transmitted is used for the deviation, and when the piston moves from the neutral position side to any direction in the axial direction. The finite time width when doing so is a value obtained by adding the correction time width to a constant basic time width tb, plus a time width for anti-elasticity proportional to the distance from the neutral position to the position where the piston is moving. ts, and in the control, the finite time width when the piston moves from any direction in the axial direction to the neutral position side is the correction time added to another constant basic time width. The value is obtained by subtracting the time width obtained by multiplying the anti-elasticity time width by a predetermined coefficient ζ from the value obtained by adding the width.

[Operation] A case where the piston moves from the neutral position side to either direction in the axial direction due to the presence of biasing forces of one spring for centering and the other spring acting on the piston; The operating force of the piston is different depending on when the piston moves from any direction in the axial direction to the neutral position side.

In order to control the position of the piston in this way,
The control of the switching valve which forces pressure oil into one of the two displacement chambers on both sides of the piston in the axial direction and releases the other into the reservoir is as follows.

In this case, from when the switching valve opens to when it closes, pressure oil is being forced into or discharged from the displacement chamber of the hydraulic actuator due to the opening, and the opening time is As time passes, the differential pressure between the pressure oils in both displacement chambers increases.

In other words, the increase in the differential pressure increases as the opening time of the switching valve increases.

For this reason, in the present invention, a: the finite time width (width of operation command time for operating the switching valve) when the piston moves from the neutral position side to either direction in the axial direction is: The value is a value obtained by adding a correction time width te to a fixed basic time width tb, and an anti-elasticity time width ts proportional to the distance from the neutral position to the position where the piston is moving.

Here, the basic time width tb is from the transmission of the command signal, which operates the switching valve, which causes a pressure difference between the pressure oil in both displacement chambers, and this pressure difference starts the piston. In this case, the activation is based on the assumption that there is no spring force acting on the piston, and the time width ts for anti-elasticity is the time from the start of activation. The correction time width te is a value proportional to the deviation Er mentioned above, and is the time width corresponding to facing the spring biasing force on either side above at that position. After overcoming the force, the time span is equivalent to shifting the piston by that deviation.

Conversely, the finite time width of the switching valve drive when the piston moves from any direction in the axial direction to the neutral position side is calculated from the value obtained by adding the correction time width to the other constant basic time width. The value is obtained by subtracting the time width obtained by multiplying the anti-elasticity time width by a predetermined coefficient ζ.

In this case, the above coefficient ζ corresponds to the auxiliary force when the piston receives the auxiliary force of the spring biasing force in the direction of movement, and the piston is controlled to the side receiving the auxiliary force. This is the correction coefficient for the component.

In this way, the above control is intended to be able to correct almost any deviation to zero when a deviation occurs in the control using only a single pulse signal corresponding to the deviation. be.

[Example] The present invention will be explained below using Examples.

FIG. 1 shows an embodiment of a hydraulic switching valve control device for carrying out the fluid actuator control method of the present invention, and the illustration is shown in the form of a system diagram.

The portion of the hydraulic switching valve operating device Y in FIG. 1 is the same as the conventional one in FIG. 8, as described above, so a description thereof will be omitted.

In FIG. 1, the signal generator 10a is the lever 1
By operating 0i, a voltage signal is transmitted to the wiring 10b, and the voltage signal is a command signal that instructs the position of the piston 1d in the hydraulic actuator 1, and the command signal is sent to the electronic control device. 10 is entered.

Output wirings 10g and 10h in the electronic control device 10 are connected to solenoids 3d and 2, respectively.
d.

The movement of the piston 1d, that is, the movement of the hydraulic switching valve 5, is detected by a potentiometer 5d,
The output wiring 10e for transmitting the detected signal serves as a feedback signal wiring in the electronic control device 10.

The circuit configuration of the electronic control device 10 is shown in FIG. 4, and is illustrated by a block diagram.

In FIG. 4, 10A is a detection storage means;
B is a deviation calculation means, 10C is a drive judgment means, 10
E represents a tolerance setting means, 10F a basic time change storage means, 10J a pulse width calculation means, 10K a basic time selection means, 10L an FB reference value setting means, and 10M an output transistor.

The operation of the configuration of the present invention shown in FIGS. 1 and 4 will be described below.

First, in the hydraulic actuator 1 shown in FIG. 1, the driving force at the beginning of activation will be considered.

FIG. 2 shows a skeleton diagram of the hydraulic actuator 1 in FIG. 1. but,
In FIG. 2, the spring 5 in FIG.
e and 5f are adapted to apply their biasing forces to the piston 1d within the hydraulic actuator 1.

In the case of FIG. 1, the springs 5e and 5f exert a biasing force on the piston 1d in the hydraulic switching valve 5, but this biasing force is the same even if it acts on the piston 1d in the hydraulic actuator 1. That's true.

Therefore, in FIG. 2, for convenience of explanation, the springs 5e and 5f are enclosed within the hydraulic actuator 1.

That is, in FIG. 2, the cylinder 1e has:
A piston 1d is fitted to enable sliding movement in the axial direction.
The biasing forces of springs 5e and 5f act in opposing directions.

The action of these two biasing forces is such that when no external force is acting on the piston 1d, the piston 1d is set at the neutral position n.

In the configuration shown in FIG. 2 as described above, when the piston 1d moves a distance x to the right from the neutral position n as shown, an axial force of approximately k1·x is applied to the piston 1d to the left. This means that it is working.

Note that k1 is a spring constant of the spring 5f.

Therefore, the starting force for moving the piston 1d further to the right from this position requires a force of approximately k1·x.

On the contrary, the moving force for moving the piston 1d further leftward from this position is a value driven by k1·x.

For the above case, the piston 1d is at the neutral position n
When the piston 1d is located at a distance x to the left from that position, the force required to activate the piston 1d is approximately k2·x when the piston 1d moves further to the left from that position.

Here, k2 is a spring constant of the spring 5e.

Moreover, the starting force when moving the piston 1d to the right from the position of the piston 1d is
The value is driven by k2 x.

That is, the types of starting force required for the piston 1d are summarized as follows.

When the piston 1d is on the right side from the neutral position n, (1) when the piston 1d tries to move in the direction of arrow a1, and (2) when the piston 1d tries to move in the direction of arrow a2, There are two types of cases: (1) When the piston 1d is to the left from the neutral position n, (1) When the piston 1d is about to move in the direction of arrow a3, and (2) When the piston When 1d attempts to move in the direction of arrow a4, there are two types of cases:

In the end, there are four basic types of force required to start the piston 1d in FIG.

Next, the above-mentioned starting force required for the piston 1d,
The relationship between the hydraulic pressure of the displacement chamber 1a or 1b necessary for its activation will be examined.

Taking as an example the case where the piston 1d is activated in the direction of the arrow a1 from the position shown in FIG. 2, the force required for activation is k1·x, as described above.

On the other hand, in order to activate the piston 1d by hydraulic pressure, it must be activated by the differential pressure dp between the hydraulic pressure generated in the displacement chamber 1a and the hydraulic pressure generated in the displacement chamber 1b. Become.

Such a pressure difference is caused by the above-mentioned switching valve 2 or 3.
When the switching valve 2 or 3 is driven by a single pulse signal with a finite time duration, the phenomenon of the differential pressure occurring is as follows.

As described above, in order to fix the piston 1d at the position shown in FIG. 2, the switching valves 2 and 3 in FIG. 1 are set to the switching position 2a and the switching position 3a, respectively.

When moving the piston 1d from the fixed position of the piston 1d in the direction of the arrow a1,
Only the switching valve 3 is set to the switching position 3b, and the switching valve 2 is set to the switching position 3b.
The switching position in is left as 2a. In addition, the method of setting the switching valve 3 to the switching position 3b is the third position of the pattern in which the solenoid 3d is turned off.
A single pulse signal V1 as shown in the figure is sent to the solenoid 3d.

In FIG. 3, the horizontal axis t indicates elapsed time, the vertical axis V indicates the output voltage of the pulse signal V1, V2, or V3, and the vertical axis p indicates the hydraulic pressure characteristics pa1,
It shows the hydraulic pressure of pa2 or pa3.

In this case, at the moment when the solenoid 3d is turned off, the working oil pressures p in the displacement chambers 1a and 1b are both approximately the same pm.
The value is .

From this state (t=0 in FIG. 3), time t
As time elapses, the working oil pressure p in the displacement chamber 1b changes as the time t elapses, as shown in the working oil pressure characteristic pa1 in FIG. At the same time, the pressure decreases toward p=0.

However, since the voltage of the pulse signal V1 is turned on again at point a, the switching position of the switching valve 3 becomes 3a, and the pressure oil in the hydraulic source 4 is again forced into the displacement chamber 1b. As shown in the hydraulic pressure characteristic pa1, the pressure then increases toward p=pm.

Therefore, the pulse signal V1 is applied to the solenoid 3d.
is transmitted, the pressure difference in the working hydraulic pressure between the displacement chamber 1b and the displacement chamber 1a is dp1
Stay in.

In this case, the value of pressure difference dp1 is the starting force mentioned above.
If the value is smaller than the value of k1・x, move the piston 1d from the x position in FIG.
cannot be moved in the direction of

In this way, if the negative application time during which the pulse signal is turned off is short, the piston 1d cannot be driven, and when the application time is set to the appropriate application time to shown in Fig. 3, the hydraulic pressure characteristics are as follows. pa2, the pressure difference becomes dp2, and the pressure difference dp2 activates the piston 1d k1・x
The value corresponds to the value of .

This value to becomes the basic application time for controlling the hydraulic actuator 1, and as explained in FIG.
must be selected in each case.

However, the pressure difference dp2 caused by this basic application time t ₀ is the minimum value necessary to start moving the piston 1d.

Therefore, in order to actually move the piston 1d, it is necessary to further use an application time obtained by adding the corrected application time te to the basic application time to, and the resulting pressure difference must be set to dp2+dpa.

That is, out of dp2 + dpa, the pressure difference dpa is a component necessary to accelerate the piston 1d, and due to the acceleration, a component necessary for the piston 1d to shift the deviation Er, and in this case, the correction application time te is a value proportional to the deviation mentioned above.

In addition, the working hydraulic characteristics resulting in the pressure difference dp2 + dpa are:
It is indicated by pa3 in FIG.

Here, as can be understood from the characteristics shown in FIG. 3 above, it can be seen that the pressure difference dp2 or dpa increases approximately in proportion to the increase in the time width to or te, respectively.

In this manner, in controlling this type of hydraulic actuator 1, the value to in FIG. 3 must be the basic application time described above.

Here, as can be understood from the explanation of FIG. 3 above, the application time to is
The time when the switch has just completed changing its switching position is defined as t=0.

However, in reality, the delay time from when the pulse signal V2 is transmitted from the electronic control device 10 until the switching valve 2 or 3 changes its switching position;
It is necessary to further consider the time tb, which takes into consideration the time required to generate a differential pressure component to overcome the static friction force component between the piston 1d and the cylinder 1e after the switching position is changed.

Further, in this case, the time delay, static friction force, etc. are approximately constant values regardless of the operating position of the piston 1d.

Therefore, when considering the actual application time from the time when the command signal is issued, the application time to in Fig. 3 is as follows:
It must be the sum of the above-mentioned time tb and the application time ts (the application time component for anti-elasticity) necessary to start the piston 1d against the biasing force of the spring 5e or 5f.

For this reason, when the hydraulic actuator 1 as shown in FIG. 1 is controlled by a single pulse signal, when the control is in the direction of compressing the spring 5F or 5e, the application time of the pulse is the basic application time that is approximately constant
tb, an anti-elasticity application time ts that changes depending on the position of the piston 1d, and a correction application time te that is proportional to the deviation Er.

Next, consider the case where the piston 1d is operated from the position of the piston 1d in FIG. 2 to the neutral position n.

In the above-described control in which the piston 1d compresses the spring 5f or 5e, the signal application time until the piston 1d is ready to start requires the addition of the ts time to the basic application time tb.

This is the basic application time tb required to reach a position to start the piston 1d when the spring 5e or 5f is not present, and also necessary to start the piston 1d against the biasing force of the spring 5f or 5e. This is because an appropriate application time component ts is required.

However, in the case where the piston 1d is returned to the neutral position n, the biasing force of the spring 5f or 5e moves the piston 1d to the neutral position n.
It becomes an auxiliary force that tries to bring it back to the side of the body.

Therefore, in control to operate the piston 1d toward the neutral position, the required time component of the signal application time until the piston 1d reaches a position where it is about to start is equal to the basic application time.
The time must be shorter than tb′.

In this case, the basic application time tb' is when attempting to return the piston 1d to the neutral position n, and assuming that the biasing force of the spring 5f or 5e is not acting on the piston 1d. The piston 1d is in the displacement chamber 1a
This is the time component for applying a signal to the switching valve 2 or 3, which is required until the valve reaches a position where it is about to be activated due to the differential pressure between the switching valves 2 and 1b.

Examining this in more detail, the spring 5f
Alternatively, the force by which the biasing force 5e tries to return the piston 1d in the direction of the neutral position n increases as the distance x that the piston 1d moves from the neutral position n increases.

In other words, in the control in which the piston 1d is operated from a distance x to a neutral position n in FIG. 2, the time obtained by subtracting a predetermined value that increases as the distance x increases from the basic application time tb' is This is the signal application time component required until the piston 1d reaches the starting position in this case.

In this case, the biasing force of the spring 5f and the differential pressure between the displacement chambers 1a and 1b press the piston 1d, whereby the displacement chamber 1a
Hydraulic oil flows out from the switching valve 2 to the reservoir 7, but the predetermined value is determined by the flow rate characteristics of the flowing hydraulic oil per unit time. 2 is determined by the flow rate coefficient through which the hydraulic oil flows.

However, this value is difficult to determine theoretically, so it must be determined experimentally.

Further, this predetermined value may be a value obtained by multiplying the above-mentioned elasticity application time ts proportional to x by a predetermined coefficient ζ, and the value of ζ may be determined experimentally.

Furthermore, it is necessary to further correct the deviation Er from the state where the piston 1d is ready to start, but if the piston 1d has reached the state where it is ready to start, that state will compress the spring 5f or 5e. Since the conditions are the same as in the case of the same posture in the control when the spring 5f or 5e is compressed, the application time component necessary to correct the deviation Er is the same as the corrected application time te when the spring 5f or 5e is compressed.

In the end, in the case of control in which the piston 1d is returned to the neutral position, the application time of one pulse applied to the solenoid 2d or 3d of the switching valve 2 or 3 must be tb'-ζ・ts+te. .

In this way, in a hydraulic actuator where the activation force is different depending on the piston's operating position, the conventional control method using only the basic application time and the corrected application time cannot be used. .

The operations in FIGS. 1 and 4 described above will be explained below.

In FIG. 1, when the operator operates the lever 10i, an analog voltage signal is generated on the wiring 10b, and this signal is input to the detection storage means 10A in FIG. 4.

Further, a signal from the potentiometer 5d that detects the position of the piston 1d is input to the detection storage means 10A as an analog signal via a wiring 10e.

The calculations in FIG. 4 after inputting to the detection storage means 10A in this way are as follows.

Calculation in the detection storage means 10A: The command signal in the wiring 10b and the feedback signal in the wiring 10e are calculated in the detection storage means 10A.
The converted command signal value is sequentially AD converted (converted from analog value to digital value) by switching in the multiplexer enclosed within the
cs and feedback signal value cf are temporarily
Stored in RAM.

Calculation in the deviation calculating means 10B: The deviation Er between the command signal value cs and the feedback signal value cf, Er=cs-cf, is calculated.

Calculation in the drive determining means 10C: The deviation Er is compared with the allowable deviation Ero, and it is determined whether a negative drive pulse signal should be output to the wiring 10g or 10h.

To specifically explain the judgment in this case,
It looks like below.

When a deviation Er occurs because the feedback signal value cf (the actual position of the piston 1d) is ahead of the command signal value cs, and the deviation Er is larger than the allowable deviation Ero, the position of the piston 1d is delayed. If a deviation Er occurs because the feedback signal value cf lags the command signal value cs, and the deviation Er is larger than the allowable deviation Ero, it is determined to advance the position of the piston 1d. , When the above deviation Er is smaller than the allowable deviation Ero,
Assuming that the control is satisfied, piston 1d
Fix it in the same position.

Note that the above tolerance Ero is the tolerance deviation setting means 1.
This is the value stored in 0E.

Calculation in the basic time change storage means 10F: This means includes each basic application time determined depending on which direction of the arrows a1, a2, a3, or a4 the piston 1d starts to move as shown in FIG. tb is memorized.

Each stored basic application time tb is modified as follows.

In other words, if any of the necessary basic application times tb is used and the control is under-driven or over-driven, this basic application time tb
is corrected by the deviation Er mentioned above.

That is, the new basic application time tb is obtained by adding or subtracting a time proportional to the absolute value of the deviation Er to the previous basic application time tb.

Below, the calculations after the pulse width calculation means 10J are as follows:
The process proceeds as follows according to the flowchart shown in FIG.

Calculation A1: Pulse width calculation starts.

Calculation A2: Calculation in the basic time selection means 10K is started, and this calculation is performed as follows according to the subroutine flowchart in FIG.

Calculation B1: Start basic time selection calculation.

Operation B2: Determine whether the feedback signal value cf is greater than or equal to the feedback reference value cfo.

Here, the value of the feedback reference value cfo corresponds to the feedback signal value cf when the piston 1d is located at the neutral position n in FIG.
This is a value stored in the reference value setting means 10L.

Therefore, the determination in calculation B2 determines whether the piston 1d is located on the right side of the neutral position n in FIG. 2, including the neutral position n.

Calculation B3: When the judgment in calculation B2 is Yes, the command signal value cs becomes the feedback signal value cf.
Determine whether it is greater than.

Operation B4: When the determination in operation B3: is Yes, tb1 is set as the basic application time tb.

The basic application time tb1 in this case corresponds to the basic application time tb in the case of arrow a1 in FIG.

Calculation B5: When the determination in calculation B3 is No, tb2 is set as the basic application time tb.

The basic application time tb2 in this case corresponds to the basic application time tb in the case of arrow a2 in FIG.

Calculation B6: When the judgment in calculation B2 is No, the command signal value cs becomes the feedback signal value cf.
Determine whether it is greater than.

Calculation B7: When the determination in calculation B6 is Yes, tb4 is set as the basic application time tb.

The basic application time tb4 in this case corresponds to the basic application time tb in the case of arrow a4 in FIG.

Calculation B8: When the determination in calculation B6 is No, tb3 is set as the basic application time tb.

The basic application time tb3 in this case corresponds to the basic application time tb in the case of arrow a3 in FIG.

The basic application times of tb1, tb2, tb3, and tb4 are stored in the basic time change storage means 10F as described above.

Here, in calculation B2 in FIG. 6 above, the feedback signal value cf is equal to the feedback reference value.
It also determines whether it is equal to cfo. That is, it is also determined whether the piston 1d is located at the neutral position n in FIG.

In this determination, the piston 1d is at the neutral position n
, the following piston 1
d is driven in the a1 direction or a from the configuration shown in Fig. 2.
It can only be driven in one of three directions.

Therefore, in the calculations after the judgment of calculation B2 becomes yes, it is judged whether cf=cfo or not, and the command signal value cs is compared to the feedback reference value cfo (neutral position n) regarding the judgment result. It is necessary to determine which direction the camera is facing, namely the a1 direction or the a3 direction.

As a result, if the judgment result is in the a1 direction, the basic application time tb is set to tb1, and if the judgment result is in the a3 direction, the basic application time tb
A program with tb3 as tb3 must be added to Figure 6.

However, in FIG. 6, this part of the program is omitted because the program explanation is complicated.

In the program of FIG. 6 omitted in this way, when the piston 1d is at the neutral position n, as can be understood from the above explanation, the calculation is the calculation B
From step 3, the process proceeds to operation B4 or B5.

As a result, in the case shown in FIG. 6, when cf=cfo and the command signal value cs outputs a command to control in the a1 direction, calculation B3 becomes yes, and
The basic application time tb in the a1 direction is set to tb1 for the a1 direction. Therefore, there is no problem in this case.

However, in the case shown in Fig. 6, when cf=cfo in calculation B2 and the command signal value cs outputs a command to control in the a3 direction, calculation B
3 becomes no, and the basic application time tb in the a3 direction becomes tb2 for the a2 direction.

In this case, the value of the basic application time tb2 corresponds to the case where the piston 1d is about to be pushed back to the neutral position n side by the spring 5f in FIG. In order to control the voltage in the a3 direction, the basic application time tb2 used in that case is smaller than the basic application time tb3, which is the ideal value in this case.

For this reason, driving the piston 1d by the first single pulse signal that controls the piston 1d from the neutral position n to the a3 side using the program shown in FIG. 6 deteriorates the responsiveness of the control. It becomes.

Here, the corrected application time is added to the shortened basic application time as described above. For this reason, in the control from the neutral position, the drive is performed by the added correction application time component. However, since the basic application time uses a shorter value for the a2 direction, the response is degraded.

However, the deterioration of its responsiveness is due to its neutral position n
It is only the control of the first single pulse transmission from .

Then, based on the control result in which the piston 1d moves in the a3 direction by the first single pulse transmission from the neutral position, for a new deviation result that naturally occurs, from the program in Fig. 6, Basic application time tb1, tb2, tb3 or tb3 adapted for each direction of a1, a2, a3 or a4, respectively.
tb4 is used, and subsequent control is in an ideal state.

After the value of the basic application time tb is determined in this way, the calculation moves to calculation B9.

Operation B9: Return the operation to operation A3 in FIG.

Calculation A3: Using the deviation Er calculated by the deviation calculation means 10B described above, calculate the corrected application time te=b・Er, and further use the corrected application time te to calculate the application time ta=tb+te. .

Here, b is a proportional constant, and tb is the basic application time tb output from the above-mentioned calculation B9.

Calculation A4: Calculation in the position correction amount calculation means 10D is performed as follows according to the subroutine flowchart shown in FIG.

Calculation C1: Start calculation of position correction amount.

Calculation C2: Calculate the transfer amount dcf=cf−cfo.

This shift amount dcf indicates how much distance x the piston 1d is displaced from the neutral position n in FIG.

Calculation C3: Determine whether the transfer amount dcf is equal to or greater than zero.

Calculation C4: When the determination in calculation C3 is Yes, calculate the anti-elasticity application time ts1, which is the application time of a value proportional to the absolute value of the shift amount dcf.

This anti-elasticity application time ts1 is determined by the electronic control device 10.
A negative pulse signal (third
It is one component of the signal application time in the pulse signal V3 (corresponding to the pulse signal V3 in the figure), and the piston 1d compresses the spring 5f by a distance x in FIG.
However, when moving further to the right in FIG. 2 from that position, this value is necessary to obtain a hydraulic pressure corresponding to the urging force of the spring 5f.

Calculation C5: When the determination in calculation C3 is No, calculate the anti-elasticity application time ts2, which is the application time of a value proportional to the absolute value of the shift amount dcf.

This anti-elasticity application time ts2 is determined by the electronic control device 10.
A negative pulse signal (third
It is one component of the signal application time in the pulse signal V3 (corresponding to the pulse signal V3 in the figure), and the piston 1d compresses the spring 5e by a distance x in FIG.
However, when moving further to the left in FIG. 2 from that position, this value is necessary to obtain a hydraulic pressure corresponding to the urging force of the spring 5e.

Operation C6: Return the operation to operation A5 in FIG.

Operation A5: Determine whether the basic application time tb is equal to tb1.

Calculation A6: When the determination in calculation A5 is Yes, the elasticity application time ts1 is added to the application time ta obtained in calculation A3, and the added value is set as the application time tn.

Here, the fact that the determination in calculation A5 is Yes means that the basic application time tb is in a state of tb1, that is, the piston 1d is in a state of operation in the direction of arrow a1 in FIG. .

Operation A7: When the determination in operation A5 is No, it is determined whether the basic application time tb is equal to tb2.

Operation A8: When the judgment in operation A7 is Yes, ts1 obtained in operation C4 (Figure 7)
Find the product α・ts1 of and the coefficient α.

In this case, the coefficient α is a coefficient determined by the flow coefficient in the switching valves 2 and 3 when hydraulic oil flows through the switching valves 2 and 3, the characteristics of the spring 5f, etc., and is an experimentally determined value. It is.

Calculation 9: Subtract α・ts1 calculated in calculation A8 from the application time ta calculated in calculation A3,
The subtracted value is set as the application time tn.

Here, the fact that the determination in calculation A7 is Yes means that the basic application time tb is in a state of tb2, that is, the piston 1d is operating in the direction of arrow a2 in FIG. .

Operation A10: When the determination in operation A7 is No, it is determined whether the basic application time tb is equal to tb3.

Calculation A11: When the determination in calculation A10 is Yes, the application time ta obtained in calculation A3
The elasticity application time ts2 is added to , and the added value is set as the application time tn.

Here, the fact that the determination in calculation A10 is Yes means that the basic application time tb is tb3, that is, the operation of the piston 1d is indicated by the arrow a3 in FIG.
This means that it is in a state where it operates in the direction of.

Calculation A12: When the judgment in calculation A10 is No, calculated in calculation C5 (Figure 7)
Find the product β·ts2 of ts2 and coefficient β.

In this case, the coefficient β is a coefficient determined by the flow rate coefficient in the switching valves 2 and 3 when the hydraulic oil flows through the switching valves 2 and 3, the characteristics of the spring 5e, etc., and is an experimentally determined value. It is.

Calculation 13: Application time ta found in calculation A3
β·ts2 calculated in operation A12 is subtracted from the equation A12, and the subtracted value is set as the application time tn.

Here, the fact that the determination in calculation A10 is No is because the operation of the piston 1d is indicated by the arrow a in FIG.
This means that it is in a state of operation in direction 4.

In addition, the application time tn obtained in calculation A6, A9, A11 or A13 above is
This is the total application time for each pulse of the negative pulse signal that the electronic control device 10 in FIG. 1 outputs to the wiring 10g or 10h.

Operation A14: The application time tn obtained in the above calculations A6, A9, A11, or A13 is output to the output transistor 10M.

In this way, as can be understood from the calculation in FIG. 5, the application time tn is as follows.

In calculation A2, a: The operation delay time from when the pulse signal is transmitted until the switching valve 2 or 3 is activated and the differential pressure in the displacement chamber caused by the operation of the switching valve are the frictional resistance of the piston 1b. In calculation A3, b: Calculate the corrected application time te proportional to the deviation Er. In calculation A4, c: In Fig. 2, the piston 1d is When compressing spring 5f or 5e by distance x,
A differential pressure dp is required in the displacement chamber 1a or 1b to counteract this compressive force.

Therefore, the elasticity application time ts required to generate the necessary component of the differential pressure dp is calculated. Therefore, when the piston 1d is compressing the spring 5f or 5e, tn=tb+te+ts (1), and in this case, the basic application time tb, corrected application time te, and anti-elasticity application time ts are each expressed as follows. These are the respective values in the case of arrow a1 or a3 in Fig. 2.

Also, in equation (1), the elasticity application time ts is added because the piston 1d is connected to the spring 5.
This is because they have to move against the affiliated forces of f or 5e.

(2) In Fig. 2, when the piston 1d moves as indicated by the arrows a2 or a4, and is assisted by the force of the spring 5f or 5e, it returns to the neutral position. is tn=tb+te-ζ・ts (2) In this case, the basic application time tb, corrected application time te, anti-elasticity application time ts and ζ are respectively the same as in the case of arrow a2 or a4 in Fig. 2. In addition, ζ corresponds to α or β in calculation A9 or A13 in FIG. 5.

Furthermore, the reason why ζ・ts is subtracted in equation (2) is because the piston 1d is pressed by the force of the spring 5f or 5e, and the piston 1d is assisted in its movement by the pressing force. The more compressed the spring 5f or 5e is, the larger ζ·ts becomes, and the shorter the application time tn becomes.

Operation in output transistor 10M: Output transistor 10M has wiring 10g and 1
There are respective transistors Tr1 and Tr2 that respectively turn on and off the voltage at 0h.

Of these, transistor Tr1 has 10g of wiring.
When a negative pulse signal (corresponding to pulse signal V3 in FIG. 3) is transmitted only to the terminal and the voltage of the wiring 10h remains on, as explained in the explanation of the operation of the hydraulic switching valve operating device Y,
Shift the piston 1d upward in FIG.
Conversely, when the transistor Tr2 sends a negative pulse signal only to the wiring 10h and the voltage on the wiring 10g remains on, the piston 1d is moved downward in FIG. 1.

In such a configuration, the output transistor 1
0M performs the following calculation.

(1) When the determination made by the drive determining means 10C is that the piston 1d should be further moved upward in FIG. 1, only the transistor Tr1 sends a negative pulse signal to the wiring 10g. do.

(2) When the determination made by the drive determining means 10C is that the piston 1d should be further moved upward in FIG. 1, only the transistor Tr2 transmits the negative pulse signal to the wiring 10h. .

In this case, the application time tn for transmitting the negative pulse signal is the application time tn output in the calculation A14.

(3) In the determination by the drive determining means 10C,
It is determined that the deviation Er is smaller than the allowable deviation Ero,
When the control is satisfied, both transistors Tr1 and Tr2 are connected to the wiring 10g.
and leave the voltage on for 10h.

As a result, the piston 1d remains fixed in that position.

In the above embodiment, the hydraulic actuator 1 in FIG. 1 is operated by hydraulic pressure, but it may be operated by other fluid pressures.

[Effects of the Invention] As is clear from the above description, the method for controlling a fluid actuator according to the present invention is such that the piston 1d in the fluid actuator has a different starting resistance force for each operating position with respect to a predetermined neutral position. Even if the configuration is such that the piston 1d is always controlled to an appropriate position, the single pulse signal used for the control always controls the piston 1d to an appropriate position.

This makes it possible to quickly control the piston 1d to the target position with just one single pulse signal transmission.

Therefore, control for each transmitted pulse becomes less wasteful control, and has the effect of easily increasing control responsiveness.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing a hydraulic switching valve control device for carrying out the method of controlling a fluid actuator according to the present invention. FIG. 2 shows the hydraulic actuator 1 in FIG. 1 in a skeleton diagram, and FIG. 3 shows the hydraulic pressure characteristics pa1, pa2, or pa3 of the displacement chamber 1a or 1b in FIG.
Pulse signal V transmitted from electronic control device 10
1. Indicate the respective characteristics of V2 or V3,
FIG. 4 shows a detailed block diagram of the electronic control unit 10 in FIG. Figure 5 shows the fourth
6 shows the subroutine of operation A2 in FIG. 5 as a flowchart, and FIG. 7 shows the subroutine of operation A4 in FIG. 5 as a flowchart. This is what is shown. FIG. 8 shows a conventional hydraulic switching valve operating device Y using a system diagram. The symbols used in the examples are as follows. 1: Hydraulic actuator, 1a and 1b: Displacement chamber, 1d: Piston, 1e: Cylinder,
n: neutral position, x: distance, 2 and 3: switching valve,
4: Hydraulic source, 5: Hydraulic switching valve, 5a, 5b and 5c: Switching position, 5d: Potentiometer, 5e
and 5f: spring, 6: hydraulic motor, 7:
Reservoir, 10: Electronic control unit, 10a: Signal generator, 10i: Lever.

Claims (1)

[Claims] 1. A piston 1d is fitted into the cylinder 1e so as to be able to slide in the axial direction, and on one side and the other side of the piston in the axial direction, a switching valve 2, 3, the piston is provided with one displacement chamber 1a and the other displacement chamber 1b into which pressure fluid is selectively pumped or expelled, and the piston has a neutral position when no external force is acting on the piston. The biasing force of one spring and the other spring for centering to set the position is applied, and the switching valve receives a single pulse signal of a finite time duration tn including a correction application time duration te.
Driven by Vn, the correction application time span is
The value is proportional to a deviation Er between a detection signal that detects the position of the piston in the axial direction and a command signal that indicates the position of the piston in the axial direction, and the deviation is proportional to the single pulse signal. In the above control in which only the value immediately before the transmission is used for each transmission, the finite time width when the piston moves from the neutral position side to any direction in the axial direction is a constant basic time. A value obtained by adding the correction time width to the width tb and an anti-elasticity time width ts proportional to the distance from the neutral position to the position where the piston is moving, and in the control, the piston The finite time width when transitions from any direction in the axial direction to the neutral position side is calculated from the value obtained by adding the correction time width to another constant basic time width, and the elasticity time width A control method for a fluid actuator characterized by comprising the above operations, wherein the value is obtained by subtracting the time width multiplied by a predetermined coefficient ζ.