JP2652023B2 - Hydraulic flow control method for hydraulic device having single rod cylinder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control method for a hydraulic control device, and more particularly to a control method for supplying hydraulic pressure to a cylinder chamber.

(Prior Art) Conventionally, in a hydraulic servo system requiring high accuracy,
It has been general to avoid using a single rod cylinder having a rod 3 extending outside the cylinder 1 from one side of a piston 2 sliding in the cylinder 1 as shown in FIG. If this is a single rod cylinder, the cylinder chamber
On the 1a side and the cylinder chamber 1b side, the pressure receiving area of the piston 2 differs by the sectional integral of the rod 3, and even if oil is supplied at the same pressure, the sliding speed differs depending on the direction of movement of the piston, and the characteristics of the system change. Therefore, it is difficult to realize a highly accurate servo system.

Therefore, in a hydraulic servo system requiring high accuracy, a double rod cylinder having rods 3, 3 extending outward from both sides of the piston 2 to the outside of the cylinder as shown in FIG. 5 (b) is used.

(Problems to be solved by the invention) However, when using both rod cylinders, in order to obtain the same cylinder stroke as a single rod cylinder, it is about 1.
It becomes three times the total length. Further, when compared in the rod operating range from one rod tip to the other rod tip, both rod cylinders need to be about 1.5 times as long as one rod cylinder. Therefore, a large space is required for installation,
There is a problem that the servo system control device is increased in size.

Further, since the number of parts is increased, the cost is higher than that of the single rod cylinder.

The present invention has been made in view of the problems of the above conventional example,
It is an object of the present invention to provide a single rod cylinder control method which can realize a highly accurate servo system using a single rod cylinder which is inexpensive and requires a small mounting space.

(Means for Solving the Problems) In order to achieve the above object, a hydraulic flow rate control method according to the present invention comprises a cylinder, a piston sliding in the cylinder, and a piston extending from one side of the piston to the outside of the cylinder. A hydraulic cylinder having a single rod cylinder that performs a sliding operation of the piston by supplying a hydraulic pressure from a servo valve that has received a control input to each cylinder chamber partitioned by the piston to a single rod cylinder having a rod that performs the sliding operation. The method of controlling the hydraulic flow rate of the apparatus is characterized in that the method is performed as follows.

When the piston rod extension side is the pressure receiving area A1 and the other side is the pressure receiving area A2, the pressure receiving areas are A1 and A2, respectively.
Then, control systems based on the linear control theory are respectively designed by considering the two rod cylinders, and two kinds of state feedback vectors are set.

The control input is a state variable vector indicating the state of the system in the multivariable control detected for each sampling time,
It is calculated by the inner product of the state feedback vector and one of the vectors.

And selecting the state feedback vector to be used at the next sampling time according to the sign of the control input,
The amount of hydraulic pressure supplied from the servo valve is controlled by a control input calculated based on the state feedback vector.

Thus, it is possible to detect at regular intervals whether the hydraulic pressure supply side is the cylinder chamber having the pressure receiving area A1 or the cylinder chamber having the pressure receiving area A2 from the sign of the control input. Alternatively, the operation can be performed assuming that both rod cylinders are A2, and optimal control can be realized in each case.

The supply of hydraulic pressure from the servo valve to the cylinder chamber is performed by moving the spool of the servo valve by a current signal from the controller and changing the opening area of the port leading to the pump.

The current signal as a control input is a state feedback vector set for each pressure receiving area A1, A2 of the piston of the single rod cylinder. And the state quantity of the control system. State variables as state variable vector And the state feedback vector is Then, the control input u becomes Required by State feedback vector Is designed to minimize the quadratic form of the evaluation function, Given by

here Satisfy the Riccati matrix equation of

Is a weight matrix for the control input u, which prevents reaching an unrealizable solution such that the power of the input becomes infinite.

Is a weight matrix for the state variables, and various state feedback vectors can be designed by increasing the weight corresponding to the state variables to be controlled with high accuracy.

Is a matrix obtained from the characteristics of the control system.For example, in a pressure-receiving area of a cylinder, or in a vibration damping device for damping a structure by operating an additional mass on the structure, the structure and the additional mass Numerical values such as mass, spring constant, and damping constant. Therefore, the pressure receiving area Or pressure receiving area Can be designed so that the single rod cylinder can be controlled as a double rod cylinder having the same pressure receiving area using the state feedback vector.

(Operation) According to the method of the present invention, it is possible to control a single rod cylinder using both rod cylinders having the same pressure receiving area, so that high-precision control can be performed irrespective of the supply direction of the hydraulic pressure to the cylinder chamber. Do.

(Example) An example of the present invention will be described with reference to the drawings.

1 to 4 show a case where the method of the present invention is applied to a vibration damping device. The vibration damping device is provided with an additional mass that can be reciprocated on a structure, and operates the additional mass to apply a reaction force to the structure to reduce vibration of the structure.

FIG. 3 shows a side view of the vibration damping device installed above the structure, and FIG. 4 shows a plan view thereof.

A rectangular parallelepiped additional mass 5 is installed at the top of the structure 4.
A single rod cylinder 6 is mounted on the peripheral surface of the additional mass 5, and one end of a rod shaft 7 of the cylinder 6 is connected to the additional mass 5.
Is connected to a wall 8 erected on the structure 4 so as to surround the structure.

The pressure receiving areas on both sides of the piston of the one rod cylinder 6 differ by the integral of the cross section of the rod shaft 7, and the small area side is A1,
The large area side is A2.

At the center of the additional mass 5, a hydraulic unit 9 for supplying oil to the cylinder 6 is installed. Wheels 10 are mounted on the bottom of the additional mass 5 so that the additional mass 5 can freely move on a horizontal plane surrounded by the wall 8 depending on how oil is supplied to the four cylinders. The horizontal plane surrounded by the wall 8
The frictional force is reduced so that the wheels 10 can move easily.

 FIG. 1 shows a model diagram of an embodiment of the present invention.

An additional mass 5 movable by a cylinder 6 is mounted on the upper part of the structure 4. In FIG. 1, the additional mass 5 is moved by one cylinder for simplification. In the actual apparatus, the structure 4 and the additional mass 5 swing in the horizontal direction, but in the model diagram, they swing in the vertical direction.

Displacement detecting means 11a as a state variable detection means to the structure 4 and the additional mass 5, 11b, provided the speed detection means 12a, 12b, respectively, displacement x ₁ of the structure 4 as the state quantity, the displacement of the additional mass 5 x ₂ detecting the speed ₂ speed ₁ additional mass 5 of the structure 4 in each sampling time, the displacement x _1, x ₂ is the state in which the structure 4, additional mass 5 is at rest to take positive and negative values as 0 I do. Also, ₁ and ₂ take positive and negative values depending on the operation direction of the additional mass.

Signals from the displacement detecting means 11a and 11b and the speed detecting means 12a and 12b are input to the controller z, where the structure 4, the additional mass 5 and the relative displacement x ₂ ′ (x ₂ −x ₁ ) and the relative displacement speed
Find ₂ '.

The controller z has two kinds of state feedback vectors for controlling the one rod cylinder 6 assuming that there are two rod cylinders equal to the pressure receiving area A1 and the pressure receiving area A2 of the piston, that is, two kinds of state feedback vectors, The state feedback vector fA1 or the state feedback vector fA2 for a large area is stored. This state feedback vector creates an optimal regulator system using both rod cylinders whose pressure receiving area is A1 or A2, and the state feedback vector for each Ask for. And this state feedback vector And a state feedback vector where all elements are 0 , A state feedback vector corresponding to the hydraulic pressure supply side is selected.

The selected state feedback vector is added to the aforementioned state quantities x ₁ , x ₂ ′, ₁ , ₂ ′. _{F 1, f 2, f 3} , multiplied by f _4, respectively, each value added by the arithmetic unit, the control input _{u = f 1 x 1 + f} 2 x 2 '+ f 3 1 + f 4 of
₂ 'is obtained.

The control input u is calculated by detecting the state quantity at every fixed sampling time. And this control input u
The state feedback vector at the next sampling time by the sign of Is selected.

When the state feedback vector switches at each sampling time, that is, when the sign of the control input u is different at each sampling time, 0 is selected as the state feedback vector to prevent the piston from flapping, and a signal for closing the servo valve 13 is output. I do.

A control input u output from the controller z is configured to energize a solenoid 15 that slides a spool 14 of the servo valve 13. Of the three ports provided on the hydraulic pressure supply side of the servo valve 13, the central port 16 communicates with the pump P (not shown), and the left and right ports 17, 18 are connected to the tank T, respectively.
(Not shown). The two ports 19 and 20 provided in the servo valve 13 communicate with the chamber of the cylinder 6 respectively. The amount of movement of the spool 14 is determined by the control input u,
The piston sliding speed is controlled by changing the opening area of the port 16 to which the hydraulic pressure is supplied and changing the flow rate of oil flowing into the cylinder chamber on the pressure receiving area A1 side or the cylinder chamber on the pressure receiving area A2 side.

In the model diagram shown in FIG. _1, the state in which oil flows out using the throttle R ₁ R ₂ and the tank is modeled in consideration of oil leakage from the seal portion of the cylinder 6.

Assuming that the structure 4 starts to swing upward (the upward direction is the right direction in the actual device) in FIG.
Displacement detecting means 11a, 11b, speed detecting means 12
The signals are detected by a and 12b, and this signal is input to a controller z to calculate a control input u.

The control input u is energized to the solenoid 15, and the spool 14 of the servo valve 13 is slid, for example, rightward in FIG. 1 to obtain a port opening corresponding to the control input. When the spool 14 slides to the right, the port 17 is closed, and the oil from the pump P flows to the port 16, the port 20, and the lower cylinder chamber to push up the piston in the cylinder 6, and the oil in the upper cylinder chamber is discharged to the port 19, guided to tank T via port 18.

As a result, the rod 7 of the cylinder 6 moves, and the additional mass 5
Is moved to the upper side, which is the same side, behind the movement of the structure 4 (the rod 7 moves in the vertical direction for the model diagram in FIG. 1).

When the sign of the control input u is reversed, the spool 14 of the servo valve 13 slides in the opposite direction, oil is supplied to the cylinder chamber opposite to the above, and the sliding speed of the piston 2 is reduced. The mass 5 is moved in the opposite direction. Therefore, the vibration of the structure 4 is reduced by applying a control force in a direction opposite to the external force to the structure by a reaction force caused by moving the additional mass 5.

At this time, since the state feedback vector selected by the controller z varies depending on the direction of supply of the hydraulic pressure to the cylinder chamber, control inputs for the same state quantity differ, and optimal control is performed respectively. If the state quantity as an external factor is the same, the piston of the cylinder 6 can be slid in the same situation regardless of the pressure receiving area difference.

In the present embodiment, a state feedback vector suitable for a situation is selected from a set of state feedback vectors depending on which hydraulic pressure is supplied to the piston surface of the pressure receiving area A1 or the pressure receiving area A2. If a plurality of state feedback vectors having different damping effects for A2 are stored, and one of the plurality of state feedback vectors is selected depending on the position of the piston, more precise control is possible.

Next, the individual state feedback vectors The setting will be described.

1. Differential equation of the system The external force is F, the force acting between the structure 1 and the additional mass 2 is U, the mass of the structure ₁ is M ₁ , the damping constant of the structure ₁ is C ₁ , and the spring constant of the structure 1 the When K _1, the equation of motion of the structure is the _{F-U = M 1 1 +} C 1 1 + K 1 x 1 (1).

Assuming that the mass of the additional mass is M ₂ , the equation of motion of the additional mass is U = M _{2 2} (2).

The pressure receiving area of the cylinder is A, and the pressure of each chamber of the cylinder is P ₁
P ₂ , cylinder damping constant C ₂ , cylinder spring constant K ₂
And then, outputs and frictional force of the cylinder and the control force considered _{zero, U = A (P 1 -P} 2) -C 2 (2 - 1) -K 2 (x 2 -x 1)
(3)

The continuous equation for the cylinder is as follows: Q _{1 is} the flow rate flowing into the cylinder from the servo valve, Q _{2 is} the flow rate flowing out of the cylinder to the servo valve, Q _{3 is} the flow rate leaking from each cylinder chamber to the outside,
Q _4, when the flow rate from the cylinder chamber at the bottom of Figure 1 leaks to the upper cylinder chamber and _{Q 5, 1 V 1 / K} = Q 1 -A (2 - 1) -Q 3 -Q 5 (4) 2 _{V 2 / K = -Q 2 +} a (2 - 1) -Q 4 + Q becomes ₅ (5).

In the model considering the flow from the cylinder chamber, R ₁
Coefficient to the stop of the formula squeeze R ₂ is _{Q 3 = R 1 P 1 Q} 4 = R 1 P 2 Q 5 = R 2 (P 1 -P 2) and made (6).

 Next, consider the characteristics of the servo valve.

The rated current of the servo valve is Ir, the rated flow is Qr, and the supply pressure is
If Ps, i ≧ 0 If i <0 Becomes

2. Linearization of differential equations Equations (7) to (10) are converted to equilibrium points (P ₁ = P ₁₀ P ₂ = P ₂₀ i =
i ₀ ) And treat ΔF as a disturbance, Expressed by Then the matrix Is a matrix of 4 rows and 4 columns and 4 rows and 1 column, respectively, and each element of the matrix is as follows.

_{A 11 = 0 A 12 = 0} A 13 = 1 A 14 = 0 A 21 = 0 A 22 = 0 A 23 = 0 A 24 = 1 A 31 = -K 1 / M 1 A 32 = K 2 / M 1 A ₃₃ = -C ₁ / M ₁ A ₃₄ = (1 / M ₁ ) 22A ² / (β + R ₁ + 2R ₂ ) + C ₂ ｝ A ₄₁ = K ₁ M ₁ A ₄₂ = -K ₂ (M ₁ + M ₂ ) / _{M 1 M 2 A 43 = C} 1 M 1 A 44 = - {(M 1 + M 2) / M 1 M 2} {2A 2 / (β + R 1 + 2R 2) + C 2} b 11 = 0 b 21 = 0 b ₃₁ = − (1 / M ₁ ) ｛2Aα / (β + R ₁ + 2R ₂ )｝ b ₄₁ = {M ₁ + M ₂ / M ₁ M ₂ ｝ ｛2Aα / (β + R ₁ + 2R ₂ )} Then, the output equation is as follows.

3. Optimal regulator design In the control system expressed by the equations (12) and (14),
Evaluation function Is determined. That is, an optimal regulator that minimizes equation (15) is designed. Control input u
Is a scalar quantity, so the input weight coefficient r is also a scalar quantity.

The weight matrix Q for the state variables is In other words, the evaluation function J is become. Here, by increasing the weight coefficient q corresponding to the state variable to be controlled with high accuracy, the control system can be freely designed from one having a large damping effect to one having a small damping effect.

The optimal input u ゜ is the optimal feedback vector (U ゜ = Δi ゜), FIG. 2 shows a block diagram of the control system.

Optimal feedback vector that minimizes J expressed by equation (15) Is the general formula Given by However, Is the only positive definite solution that satisfies the Riccati matrix equation

When the pressure receiving area A is calculated as the pressure receiving area A1 or the pressure receiving area A2 at the time of setting the above-described state feedback vector, the control system is configured using both the rod cylinders of the pressure receiving area A1 or the pressure receiving area A2. be able to.

In the embodiment described above, the state variable vector is the displacement x _{1 of} the structure 4, the relative displacement x ₂ ′ of the additional mass 5 with respect to the structure 4,
Speed ₁ of structure 4, relative speed of structure 4 and additional mass 5
_Although represented by ₂ ', other variables related to vibration and variables related to control of the hydraulic cylinder may be considered as state quantities.

That is, the displacement of the structure 4 at the vibration damping device mounting position
x ₁ , displacement x ₂ of the additional mass 5, displacement x ₀ of the lowest part or the ground of the structure 4, relative displacement x ₂ ′ of the additional mass 5 following the structure 4,
Cylinder chambers of the pressure p _1, p _2, and the displacement x ₃ of the spool 14 of the servo valve 13 may represent a state variable vector retrieving the key elements in the control from this. In this case, the evaluation function J
It is appropriate to do as follows.

In consideration of the compressibility of oil, it is effective to add p ₁ p ₂ .

When When (Effect of the Invention) According to the method of the present invention, in the method for controlling the hydraulic flow rate of a hydraulic device having a single rod cylinder, when the piston rod extension side is a pressure receiving area A1 and the other side is a pressure receiving area A2,
Assuming that the pressure receiving areas are both rod cylinders A1 and A2, respectively, control systems based on linear control logic are designed and two types of state feedback vectors are set in advance, and the inner product of the state variable vector and the state feedback vector is used. Depending on the sign of a certain control input, the hydraulic pressure supply side
The cylinder chamber of A1 or the cylinder chamber of the pressure receiving area A2 can be detected at regular intervals, and accordingly, the hydraulic pressure flow rate is controlled by regarding the two pressure cylinders as the pressure receiving area of A1 or A2. Therefore, the control can be performed using both rod cylinders each having a pressure receiving area equal to each pressure receiving area using a single rod cylinder, and highly accurate control can be performed regardless of the hydraulic pressure supply direction.

Therefore, a high-precision hydraulic servo system can be configured by a single rod cylinder that is inexpensive and has a small mounting space.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a model diagram of a vibration damping device showing an embodiment of the present invention,
2 is a block diagram of a control system, FIG. 3 is a side view of a vibration damping device using the present invention, FIG. 4 is a plan view of the vibration damping device, and FIGS. It is explanatory drawing which shows both rod cylinders. 4 Structure 5 Additional mass 6 Cylinder 7 Rod shaft 11a, 11b Displacement detecting means 12a, 12b Speed detecting means z Controller

Claims (1)

(57) [Claims] 1. A single rod cylinder having a cylinder, a piston sliding in the cylinder, and a rod extending from one side of the piston to the outside of the cylinder, each cylinder chamber partitioned by the piston. A hydraulic flow rate control method for a hydraulic device having a single rod cylinder that performs a sliding operation of the piston by supplying a hydraulic pressure from a servo valve that has received a control input to the piston, wherein the rod extension side of the piston is a pressure receiving area A1 and the other side is Is the pressure receiving area A2, the pressure receiving area is regarded as both rod cylinders A1 and A2, respectively, and a control system based on linear control theory is designed to set two types of state feedback vectors, and the control input is: A state variable vector indicating the state of the system in the multivariable control detected at each sampling time, and the state foot vector A state feedback vector to be used at the next sampling time is selected based on the sign of the control input, and a servo valve is calculated based on the control input calculated based on the state feedback vector. A hydraulic flow control method for a hydraulic device having a single rod cylinder, comprising controlling a hydraulic supply amount from a hydraulic cylinder.