JPH0381001B2 - - 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. 9 is a system diagram showing a conventional hydraulic switching valve operating device Y, in which the hydraulic switching valve 5 that hydraulically controls the hydraulic motor 6 is located at switching positions 5a, 5b, and 5c, whose switching position is operated by the hydraulic actuator 1 or the lever 1c, and the hydraulic actuator 1
The pressure oil is forced to be fed to or removed from the displacement chamber 1a or 1b by operating the switching valve 2 or 3.

The solenoids 2b 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 pressure oil switching valve operating device Y shown in FIG. 9 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 shown in FIG. 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 the displacement chambers 1a and 1b are open to the respective reservoirs 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 positions 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. 9,
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 hydraulic switching valve operating device Y is operated by operating the switching valve 2 or 3 using the manual switch 11, and whether or not the operation is appropriate is determined by
The operator operates the hydraulic motor 6 while observing the movement of the load.

However, since the remote control of the switching valve 2 or 3 shown in FIG. 9 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 desirable 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 corrected just by the single pulse.

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, a command signal indicating the position of the piston 1d is transmitted, a feedback signal indicating the current position of the piston 1d is obtained, a deviation is calculated as the difference between the two signals, and a deviation is calculated based on the deviation. The control immediately before the single pulse signal is transmitted is normal feedback control. 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. 9 above, the hydraulic actuator 1 to be controlled by the switching valves 2 and 3 cannot be controlled in each operating direction due to the presence of the centering springs 5e and 5f. The driving force at which the piston 1d starts to actuate at these positions is different.

Therefore, when the conventional method is used to control a hydraulic actuator in which such a spring biasing force exists, there is a drawback that the control response is degraded.

An object of the present invention is to control a fluid actuator whose actuating force differs depending on the operating direction and each operating position of the piston 1d, as described above, by correcting the deviation by one single pulse signal transmission. The objective is to provide a control method.

[Means for Solving the Problem] A cylinder fitted with a piston to enable sliding movement in the axial direction is provided with one displacement chamber and the other displacement chamber on both sides of the piston in the axial direction. , the piston is given a biasing force of one spring and the other spring for centering to set the piston to a neutral position when no external force is acting on the piston, and the one displacement chamber is , through one switching valve,
The pressure fluid is selectively pumped or discharged, and the pressure fluid is selectively pumped or discharged into the other displacement chamber via the other switching valve, and the one switching valve When a deviation occurs between a detection signal value that detects the position of the piston in the axial direction and a command signal value that indicates the position of the piston in the axial direction, the valve and the other switching valve control the switching valve in a finite time period. In conventional control driven by one pulse signal or more, 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 width. , a value that is the sum of a correction time width that is proportional to the deviation between the command signal and the detection signal and an anti-elasticity time width that is proportional to the distance from the neutral position to the position where the piston is moving; The finite time width when the piston moves from any position in the axial direction to the neutral position side is another constant basic time width,
The value is the sum of the deviation and the time width obtained by integrating a predetermined value, and the predetermined value is the sum of the constant value and a value proportional to the distance from the neutral position to the position where the piston is moving. It is characterized by being a reciprocal value.

[Function] As described above, the hydraulic actuator to be controlled used in the present invention has two types of piston strokes: one for the forward stroke and one for the return stroke due to the presence of the spring biasing force. , which are configured to generate load forces of different magnitudes.

In such a switching valve that controls a hydraulic actuator, while pressurized oil is being force-fed or discharged into the displacement chamber of the hydraulic actuator by opening the switching valve, the pressure oil in the displacement chamber increases over time as the valve opens. The differential pressure increases. That is, the longer the opening time of the switching valve, the greater the differential pressure generated in the displacement chamber.

This is due to the length of the valve opening time in the switching valve,
This corresponds to the magnitude of the load force on the hydraulic actuator.

For this reason, when a deviation occurs between the actual transition position of the hydraulic actuator and the command signal value indicating the new position of the transition position, a single pulse signal is transmitted, and while the signal is applied, In a method of operating a switching valve and controlling its deviation within an allowable range by issuing a single signal only once, the single signal application time has been improved as follows.

The finite time width of the single pulse application when the piston moves from the neutral position side to either direction in the axial direction is a constant basic time width,
The value is the sum of a correction time width that is proportional to the deviation and a time width for elasticity that is proportional to the distance from the neutral position to the position where the piston is moving.

In other words, when the piston is moved by increasing the differential pressure in the displacement chamber in the direction opposite to the spring biasing force, an increase in the differential pressure corresponding to the amount by which the spring is compressed is generated in the displacement chamber. In addition, the application time for elasticity is added.

In addition, the finite time width when the piston moves from any position in the axial direction to the neutral position is calculated by adding another constant basic time width and the time width obtained by integrating the deviation with a predetermined value. The predetermined value is the reciprocal of the sum of a constant value and a value proportional to the distance from the neutral position to the position where the piston has moved.

Here, when the piston is moved in the direction in which the spring force acts, the above-mentioned predetermined value is determined by taking into account the component corresponding to the spring force and inversely proportional to the above single value. This shortens the time width of signal application.

This also makes it possible to correct almost any deviation to zero when a deviation occurs in the control by sending only one single pulse signal corresponding to the deviation. It means that.

[Example] Hereinafter, the present invention will be explained based on Examples.

FIG. 1 shows a hydraulic switching valve control device for carrying out the method of controlling a fluid actuator according to the present invention, and is illustrated in the form of a system diagram.

As mentioned above, the hydraulic switching valve operating device Y in FIG. 1 has a conventional configuration.
Since its configuration has already been explained in FIG. 9, its explanation 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 for commanding 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 the potentiometer 5d, and the output wiring 10 transmits the detected signal.
Reference character e is a wiring for a feedback signal in the electronic control unit 10.

The circuit configuration of the electronic control device 10 is shown in FIG. 5, and is illustrated by a block diagram.

In FIG. 5, 10A is a detection storage means;
B is a deviation calculation means, 10C is a drive judgment means, 10
D is position correction amount calculation means, 10E is tolerance setting means, 10F is basic time change storage means, 10J is pulse width calculation means, 10K is basic time selection means,
10L indicates an FB reference value setting means, and 10M indicates an output transistor.

The operation of the embodiment shown in FIG. 1 above will be explained below.

First, at each operating position of the hydraulic actuator 1 in FIG. 1, the operating force at the beginning of activation will be analyzed.

FIG. 2 shows a skeleton diagram of the hydraulic actuator 1 in FIG. 1.

However, in FIG. 2, the springs 5e and 5f in FIG.
The force is applied to the piston 1d within the piston 1d.

In FIG. 1, the springs 5e and 5f are connected to the piston 61 in the hydraulic switching valve 5.
This additional force exerts an additional force on the piston 1d within the hydraulic actuator 1.
The same thing applies if it acts on

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, and a spring 5e is attached to the piston 1d in the axial direction and near the neutral position n.
and 5f act in mutually opposing directions, and their action is such that when no external force is acting on the piston 1d, the piston 1d is set at the neutral position n.

As described above, in the configuration shown in FIG. 2, 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 further moving the piston 1d to the right from this position of the piston 1d requires approximately a force of k1·x.

On the contrary, when moving the piston 1d to the left from this position, in addition to the hydraulic pressure in the displacement chamber 1b, the k1 x also acts as an auxiliary force to drive the piston 1d to the left. .

Further, since the configuration in FIG. 2 is symmetrical, the same situation as described above occurs even when the piston 1d is located to the left of the neutral position n.

However, the spring constant of the spring 5e and the spring constant of the spring 5f are not necessarily the same.

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. On the other hand, when the piston 1d is to the left from the neutral position n, 1. The piston 1d is about to move in the direction of arrow a3, and 2. The piston 1d is moving in the direction of arrow a4. When attempting to do so, there are two types of cases.

After all, in FIG. 2, there are four basic types of force required to start the piston 1d in any direction from any of its fixed positions.

Next, the relationship between the value at which the piston 1d is activated against the spring 5e or 5f and the hydraulic pressure of the displacement chamber 1a or 1b required for activation will be analyzed.

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.

When such a pressure difference is generated by operating the switching valve 3 mentioned above, and when the switching valve 3 is operated by a pulse signal with a finite time width, the phenomenon that causes the pressure difference is as follows. It becomes like this.

As described above, in order for the piston 1d to be fixed 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,
The method of switching only the switching valve 3 to the switching position 3b, leaving the switching position of the switching valve 2 as 2a, and setting the switching valve 3 to the switching position 3b is shown in FIG. 3 in a pattern in which the solenoid 3d is turned off. A pulse signal V1 like this is transmitted from the electronic control device 10 to the solenoid 3d.

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

In this case, after the electronic control device 10 sends the pulse signal V1 to the solenoid 3d,
Since there is a delay time tb until the switching valve 3 changes its switching position to 3b, when the switching valve 3 opens, the pulse signal V in the electronic control device 10
It will be tb time after 1 is sent.

Furthermore, at the moment when the switching valve 3 opens, the working oil pressures p in the displacement chambers 1a and 1b are both approximately the same value pm.

From this state (t=tb 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=O.

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. Its characteristics are the hydraulic pressure characteristics pa in Figure 3.
The pressure is increased as shown in 1.

Therefore, the pulse signal V1 is applied to the solenoid 3d.
As a result, the maximum pressure difference in the working hydraulic pressure between the displacement chamber 1b and the displacement chamber 1a is dp
Stay at 1.

In this case, the value of the pressure difference dp1 is the above-mentioned starting force k
When the value is smaller than the value corresponding to 1.x, the piston 1d cannot be moved from the x position in FIG. 2 in the direction of the arrow a1.

In this way, if the negative application time during which the pulse signal is turned off is short, the piston 1d cannot be operated, and when the application time is set to the appropriate application time tb+ts (pulse V2) shown in FIG. 3, The hydraulic pressure characteristics are as shown in pa2, and the maximum pressure difference is dp.
2, and the maximum pressure difference dp2 becomes a value corresponding to the value of k1·x that activates the piston 1d.

Further, the maximum pressure difference dp2 caused by this application time tb+ts is the minimum value necessary to start moving the piston 1d.

Therefore, in order to actually move the piston 1d, use the pulse signal V3 whose application time is the addition of the corrected application time te to this application time tb+ts.
The maximum pressure difference resulting therefrom must be dp2+dpa.

Note that the hydraulic pressure characteristic resulting in the pressure difference dp2+dpa is indicated by pa3 in FIG.

As can be understood from FIG. 3, it will be understood that the value of dp2 or dpa increases almost uniformly in proportion to the increase in the application time ts or te.

In other words, out of dp2+dpa, the pressure difference dp2 is a value proportional to the above k1・x, and since that value is a value proportional to the application time ts, the application time ts is also proportional to k1・x. need to be.

In addition, since the pressure difference dpa is a necessary component to accelerate the piston 1d and correct the above deviation, the pressure difference dpa is a value proportional to the deviation, and the application time te is also proportional to the deviation. The value must be as follows.

Therefore, in controlling this type of hydraulic actuator 1, the value tb+ts in FIG. 3 must be the conventional basic application time described above.

Note that the time delay tb is a substantially constant value that is independent of the operating position of the piston 1d.

Due to this, when the hydraulic actuator 1 as shown in FIG. 1 is controlled by a pulse signal against the spring 5e or 5f,
The application time of the pulse needs to be controlled using a basic application time tb, which is a nearly constant value, an anti-elasticity application time ts, which changes depending on the position of the piston 1d, and a corrected application time te, which is proportional to the deviation Er. This means that the conventional control method using only a constant basic application time and a corrected application time proportional to the deviation cannot be used.

That is, this problem arises because the activation force of the hydraulic actuator 1 differs depending on the operating position of the piston 1d.

Next, when the control is performed against the spring 5e or 5f as described above, the piston 1d is moved to the neutral position by the urging force of the spring 5e or 5f and the hydraulic pressure in the displacement chamber 1a or 1b. The case of being driven to the side will be analyzed below.

When the piston 1d is returned to the neutral position n, its operation is essentially the same whether it is indicated by arrow a2 or arrow a4 in FIG. The case of returning from the state shown in the figure to the neutral position n will also be analyzed as a representative example.

When the piston 1d is fixed at the position shown in FIG. 2, the switching positions of the switching valves 2 and 3 are 2a and 3a, respectively, as described above.
are set for each.

In this case, in this state, the hydraulic source 4
On the one hand, the operating oil pressure of the check valve 3c is
and is transmitted to the displacement chamber 1b via the switching valve 3, and on the other hand, the check valve 2c and the switching valve 2.
It can be transmitted to the displacement chamber 1a via.

However, in this case, the force that presses the piston 1d from the side of the displacement chamber 1a is
However, the force that presses the piston 1d from the side of the displacement chamber 1b is due to the hydraulic pressure p in the displacement chamber 1b.
This is due to the pressing force of the spring 5f and the urging force of the spring 5f.

Therefore, the working oil pressure p in the displacement chamber 1a becomes larger than the working oil pressure po in the displacement chamber 1b, and the check valve 2c is closed by the working oil pressure p, and the hydraulic pressure source 4 is supplied to the displacement chamber 1b.
The operating hydraulic pressure is connected to the lead.

That is, in this state, the equilibrium equation of the axial force acting on the piston 1d is A・p=A・po+k1・x, and rearranging this, p=po+(k1/A)x...( 1) becomes.

In this state, a pulse signal (fourth
When a pulse signal Vr (corresponding to the pulse signal Vr in the figure) is transmitted, the solenoid 2d is activated by the switching valve 2.
Switch the switching position to 2b.

However, as described above, the time required for this switching to be completed requires a basic application time of tb.

When the switching valve 2 is switched to the switching position 2b in this way, the hydraulic oil in the displacement chamber 1a will be discharged to the reservoir 7 via the switching valve 2. When flowing through the pipe, the hydraulic fluid is squeezed out as it flows out.

Therefore, after the switching valve 2 is opened, the working oil pressure in the displacement chamber 1a gradually decreases.
Its characteristics are shown in FIG.

Here, the relationship between the hydraulic pressure p in the displacement chamber 1a and the flow rate Q of the hydraulic oil flowing out of the switching valve 2 after the switching valve 2 is opened is as follows, as a characteristic when flowing through a general orifice: p= This can be shown by the relationship ζ・Q・Q (2), but since this valve is opened to correct a minute deviation of the piston 1d, the time it is open is very short. The problem should be the time.

Therefore, equation (2) is approximately p=ζ・Q (3) It can be done.

Here, ζ is a constant value including the flow coefficient as long as the temperature of the hydraulic oil is constant.

Furthermore, since the piston 1d is pushed toward the neutral position n and the amount of hydraulic oil that the piston 1d displaces within the displacement chamber 1a is equal to the above Q, Q=A・v (4 ) is established.

However, v is the speed of the piston 1d.

In the end, from equations (1), (3) and (4), v=(po/A・ζ)+(1/A・ζ)・(k1/A)・
x (5).

In this case, as long as the temperature of the hydraulic oil is constant, the first term and the second term (1/A·ζ)(k1/A) in equation (5) are constant values.

Therefore, (po/A・ζ)=α (1/A・ζ)(k1/A)=β Then, equation (5) becomes v=α+(β・x) (6) becomes.

Further, the distance e that the piston 1d moves during the short period of time tx during which the switching valve 2 is open is as follows: e=v·tx (7).

As a result, from equations (6) and (7), tx=e/{α+(β・x)} (8) get.

In this case, if the distance e corresponds to the deviation Er in the control, the control will be satisfactory.

That is, when e=Er is substituted in equation (8), and the valve opening time tx is tr, equation (8) becomes tr=Er/{α+(β・x)} (9), and this If the application time tn of one pulse sent to the solenoid 2d is the time obtained by adding tb in Fig. 4 to the tr in equation (9), then the control can be satisfactorily controlled by transmitting only that one pulse. Become.

Based on the explanations in Figures 2 to 4 above,
The operation in FIG. 1 will be explained below.

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. 5.

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

The calculations in FIG. 5 after inputting to the detection storage means 10A in this way are as follows.

Calculation in detection storage means 10A: wiring 10b
The command signal at and the feedback signal at the wiring 10e are sequentially AD converted (converted from an analog value to a digital value) by switching in a multiplexer included in the detection storage means 10A, and the converted command signal The value cs and the feedback signal value cf are each temporarily stored in RAM.

Calculation in deviation calculation means 10B: Command signal value
Calculate the deviation Er between cs and the feedback signal value cf, Er=cs−cf.

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.

A detailed explanation of the determination in this case is as follows.

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 (the actual position of the piston 1d) lags the command signal value cs, and the deviation Er is larger than the allowable deviation Ero, the piston 1d If 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 tb determined depending on whether the piston 1d is activated in the direction of the arrows a1, a2, a3 or a4 explained in FIG. 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,
The correction is made by adding the deviation to the basic application time tb from the previous time.
The new basic application time is a value obtained by adding or subtracting a time proportional to the absolute value of Er.

Hereinafter, calculations after the pulse width calculation means 10J proceed as follows according to the flowchart shown in FIG.

Calculation A1: Pulse width calculation calculation starts.

Calculation A2: Calculation in the basic time selection means 10K is started, and this calculation is performed as follows according to the flowchart of the subroutine shown 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 is to determine 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.
Determine whether it is greater than cf.

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

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

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

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

Operation B6: When the determination in operation B2 is No, it is determined whether the command signal value cs is greater than the feedback signal cf.

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

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, the basic application time tb is set to tb3.

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.

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

Calculation A3: Calculate the correction application time te=b·Er using the deviation Er calculated by the deviation calculating means 10B described above.

Note that b is a proportionality constant.

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.

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

This shift amount dcf corresponds to the distance x in FIG.

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

Calculation C4: When the determination in calculation C3 is Yes, calculate the elasticity application time ts1 of a value proportional to the absolute value of the transfer 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 Figure 2.
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 elasticity application time ts2 with a value proportional to the absolute value of the transfer amount dcf.

This anti-elasticity application time ts2 is determined by the electronic control device 10
The piston 1d, which is one component of the signal application time in the negative pulse signal output from the wire 10h to the wiring 10h, and which has compressed the spring 5e by a distance x in FIG. 2, further moves to the left in FIG. 2 from that position. In this case, 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.

Calculation A5: The following calculation is performed using the deviation Er calculated in the deviation calculation means 10B and dcf calculated in calculation C2.

tr1=Er/{α1+(β1・|dcf|)} tr2=Er/{α2+(β2・|dcf|)} In the above two equations, each of tr1, tr2, α1, β1, α2, and β2 is the second In the figure, piston 1
This corresponds to tr, α, and β in equation (9) when d is on the right side and the left side of the neutral position n.

Operation A6: Determine whether the basic application time tb is equal to tb1.

Operation A7: When the judgment in operation A6 is Yes, calculate tn=tb+te+ts1.

Here, the fact that the determination in calculation A6 is Yes means that the basic application time tb is tb1, that is, the piston 1d is operating in the direction of arrow a1 in Fig. 2. .

Operation A8: When the determination in operation A6 is No, it is determined whether the basic application time tb is equal to tb2.

Operation A9: When the determination in operation A8 is Yes, calculate tn=tb+tr1.

Here, the fact that the determination in calculation A8 is Yes means that the basic application time tb is tb1, that is, the piston 1d is operating in the direction of arrow a1 in Fig. 2. .

Operation A10: When the determination in operation A8 is No, it is determined whether the basic application time tb is equal to tb3.

Operation A11: When the determination in operation A10 is Yes, calculate tn=tb+te+ts2.

Here, the fact that the determination in calculation A10 is Yes means that the basic application time tb is in a state of tb3, that is, the piston 1d is operating in the direction of arrow a3 in Fig. 2. .

Operation A12: When the determination in operation A10 is No, calculate tn=tb+tr2.

Here, the fact that the determination in calculation A10 is No is because the operation of the piston 1d is indicated by the arrow in FIG.
This means that it is in a state where it operates in the direction of A4.

In addition, the application time tn obtained in calculation A7, A9, A11 or A12 in the above is the total application time for each pulse of the negative pulse signal that the electronic control unit 10 outputs to the wiring 10g or 10h in FIG. It is a familiar thing.

Operation A13: The application time tn obtained in the above calculations A7, A9, A11 or A12 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: Calculate the basic application time tb, taking into consideration the operation delay time from when the pulse signal is sent until switching valve 2 or 3 completes operation, and in calculation A3, b: Proportional to the deviation Er. In calculation A4, c: In Fig. 2, when the piston 1d compresses the spring 5f or 5e by a distance x, there is a force in the displacement chamber 1a or 1b against this compression force. Differential pressure dp is required.

Therefore, the elasticity application time ts required to generate the required differential pressure dp component
1 In Fig. 2, when the piston 1d moves as indicated by arrows a1 or a3 and compresses the spring 5f or 5e, tn=tb+te+ts (10). In this case, the basic application time tb, the corrected application time te, and the anti-elasticity application time ts are the respective values in the case of arrow a1 or a3 in FIG. 2, respectively.

Furthermore, the reason why the anti-elasticity application time ts is added in equation (10) is that the piston 1d must move against the biasing force of the spring 5f or 5e.

2 In Fig. 2, when the piston 1d moves in the direction of arrows a2 or a4 and is assisted by the force of the spring 5f or 5e, returning to the neutral position n. tn=tb+tr (11) In this case, the basic application time tb and the return application time tr are the respective values in the case of arrow a2 or a4 in FIG. 2.

Also, as can be understood from equation (9), tr in equation (11) is spring 5e or 5f.
is compressed, and the larger the compression amount x, the smaller the value.

This is because the greater the amount of compression, the greater the force applied by the spring 5e or 5f, which pushes the piston 1d back more strongly. This means that the opening time of valves 2 or 3 must be shortened.

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.

Among these, when the transistor Tr1 sends a negative pulse signal only to the wiring 10g and the voltage remains on to the wiring 10h, as explained in the explanation of the operation of the hydraulic switching valve operating device Y, the piston 1d is activated. Moving upward in FIG. 1, conversely, transistors Tr1 and Tr2 transmit a negative pulse signal only to the wiring 10h, and
When the voltage 0g remains on, the piston 1d is moved downward in FIG. 1.

In such a configuration, the output transistor 10M performs the following calculation.

1 When the content of the deviation Er in the deviation calculating means 10B is that the piston 1d should be further moved upward in FIG. 1, only the transistor Tr1 is connected to the wiring 10.
Send a negative pulse signal to g.

2. When the content of the deviation Er in the deviation calculating means 10B is such that the piston 1d should be further moved downward in FIG.
The above negative pulse signal is transmitted to h.

In this case, the application time tn for transmitting the negative pulse signal is the application time tn output in the calculation A12.

3. In the deviation calculating means 10B, when the deviation Er is determined to be smaller than the allowable deviation Ero and the control is satisfied, both the transistors Tr1 and Tr2 are connected to the wirings 10g and 10h.
Leave the voltage on.

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

Although the embodiment of the present invention is constructed and operates as described above, the construction of the above embodiment may be as follows.

That is, although the hydraulic actuator 1 in FIG. 1 is operated by hydraulic pressure, it may be operated by other fluid pressures.

[Effect of the invention] The piston 1d in the fluid actuator is
Even if the configuration is such that each operation position is affected by the spring force, the signal for each pulse signal used to control the position of the piston 1d is dependent on each load force occurring on the piston 1d. Since each application time has a component corresponding to the component, the piston 1d is always controlled to an appropriate position each time the signal is transmitted.

Therefore, the control is almost always capable of correcting deviations with only the one single pulse signal transmission. As a result, it becomes easy to improve control responsiveness.

[Brief explanation of drawings]

FIG. 1 shows a system diagram of a hydraulic switching valve control device for implementing the fluid actuator control method of the present invention, and FIG. 2 shows a skeleton diagram of the hydraulic actuator 1 in FIG. FIG. 3 shows the hydraulic pressure characteristics pa1, pa of the displacement chamber 1a in FIG. 2 when the piston 1d shown in FIG. 2 moves to the right.
2 or pa3 and the characteristics of the pulse signals V1, V2, or V3 transmitted from the electronic control device 10, and FIG. 4 shows the displacement chamber when the piston 1d shown in FIG. 2 moves to the left. 1
Indicates the hydraulic pressure characteristic pa4 at a and the pulse signal Vr sent to the switching valve 2 in this case,
5 shows a detailed block diagram of the electronic control device 10 in FIG. 1, FIG. 6 shows a flowchart of pulse width calculation in FIG. 5, and FIG.
6 shows a subroutine of calculation A2 in FIG. 6 as a flowchart, FIG. 8 shows a subroutine of calculation A4 in FIG. 6 as a flowchart, and FIG. 9 shows a conventional hydraulic switching valve control system. is shown using a system diagram. The symbols used in the examples are as follows. 1...Hydraulic actuator, 1a and 1b...
...displacement chamber, 1c... lever, 1d... piston, 1e... cylinder, n... neutral position, x...
Distance, 2 and 3...Switching valve, 2a, 2b, 3a
and 3b... switching position, 2d and 3d... solenoid, 5... hydraulic switching valve, 5a, 5b and 5c... switching position, 5d... potentiometer,
5e and 5f...Spring, 6...Hydraulic motor, 7...Reservoir, 10...Electronic control device 1
0, 10a...Signal generator.

Claims (1)

[Scope of Claims] 1. A cylinder into which a piston is fitted to enable sliding movement in the axial direction is provided with one displacement chamber and the other displacement chamber on both sides of the piston in the axial direction, The piston is given biasing force by one spring and the other spring for centering to set the piston to a neutral position when no external force is acting on the piston, and the one displacement chamber has one The pressure fluid is selectively pumped or discharged through the switching valve, and the pressure fluid is selectively pumped or discharged into the other displacement chamber via the other switching valve. and the one switching valve and the other switching valve have a deviation between a detection signal value that detects the axial position of the piston and a command signal value that indicates the axial position of the piston. When the piston is driven by a single pulse signal with a finite time width or more, the finite time width is constant when the piston moves from the neutral position side to any direction in the axial direction. , a correction time width proportional to the deviation, and an anti-elasticity time width proportional to the distance from the neutral position to the position where the piston is moving; The finite time width when transitioning from any position in the axial direction to the neutral position side is different from another constant basic time width,
The value is the sum of the deviation and the time width obtained by integrating a predetermined value, and the predetermined value is the sum of the constant value and a value proportional to the distance from the neutral position to the position where the piston is moving. A control method for a fluid actuator in which the value is the reciprocal of .