JPH09282005A - Position control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent overshoot in PI control. SOLUTION: A target position XT is set (S1), an actual position XA is detected (S2) and a deviation ΔX=XT-XA is calculated (S3). Then, proportion quantity correction quantity P=Gp.ΔX (Gp is prescribed proportion gain) is calculated (S4). A deviation ΔX is integrated and integration quantity correction quantity I=I+Gi.ΔX (Gi is prescribed integration gain) is calculated (S6). As the absolute value |ΔX| of the deviation is larger, the integration gain Gi is reduced (S5), and integration quantity correction quantity I in a state where the deviation is large is reduced. Proportion quantity correction quantity P and integration quantity correction quantity I are added and correction quantity (correction duty) PI=P+I is calculated (S7). Correction duty PI is added to 50% of a basic duty and a controlled variable (control duty) =50+PI is calculated (S8).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position control device for feedback controlling the position of a controlled object to a target position.

[0002]

2. Description of the Related Art Conventionally, for example, in a variable valve mechanism for variably controlling the opening / closing timing of intake and exhaust valves of an internal combustion engine, an actuator for driving a valve timing control member in the variable valve mechanism is provided, and the valve timing control member is provided. The opening / closing timing of the intake / exhaust valve is controlled by the position control of.

Specifically, as shown in FIG. 2, as an actuator, a hydraulic cylinder 1 for driving a valve timing control member and a flow of hydraulic pressure to two hydraulic working chambers A and B of the hydraulic cylinder 1 are controlled. And a solenoid valve 2 that operates. In the hydraulic cylinder 1, the position of the valve timing control member can be determined by the stroke position of the output rod 1a, and thus the opening / closing timing of the intake / exhaust valve can be determined.

When the solenoid valve 2 is in the ON position, the oil pump 3
From the oil pump 3 to the one hydraulic working chamber A and drain the hydraulic pressure from the other hydraulic working chamber B to guide the hydraulic pressure from the oil pump 3 to the other hydraulic working chamber B at the OFF position. The hydraulic pressure in the hydraulic working chamber A is drained. Therefore, by controlling the duty (ON time ratio) of the solenoid valve 2 by the control unit 4 to drive the solenoid valve 2 by duty, the stroke position of the hydraulic cylinder 1 is adjusted and the opening / closing timing of the intake / exhaust valve is controlled. You can

The hydraulic cylinder 1 projects by making the duty of the solenoid valve 2 larger than 50%, and the hydraulic cylinder 1 becomes smaller by making the duty smaller than 50%.
Is retracted. By setting the duty to 50%, the neutral state is established, and the operation position at that time is almost stopped. On the other hand, in order to feedback control the opening / closing timing of the intake / exhaust valve of the internal combustion engine to a target timing according to the engine operating state (engine speed and load), the stroke position of the hydraulic cylinder 1 is feedback controlled to the target position. It goes as follows.

A position sensor 5 for detecting the actual position of the tip of the output rod 1a is provided, and a signal from this position sensor 5 is input to the control unit 4. The control unit 4 sets the target position at predetermined time intervals, detects the actual position, and calculates the deviation between the target position and the actual position. Then, a proportional correction amount P proportional to the deviation and an integral correction amount I obtained by integrating the deviation are calculated and added to obtain a correction amount (correction duty).
Calculate PI = P + I. Then, the control amount (control duty) for the solenoid valve 2 is calculated based on this correction amount. Specifically, the control duty for the solenoid valve 2 is calculated by adding the correction duty PI to the basic duty of 50%.

[0007]

However, in the PI feedback control in such a conventional position control device, when the target position changes stepwise, after the actual position catches up with the target position by the feedback control,
There is a problem that it does not converge and a large overshoot occurs.

That is, referring to FIG. 5, when the target position changes stepwise, the deviation between the target position and the actual position becomes large, so that a large proportional correction amount (P) occurs and the actual position is targeted. However, separately from this, since the integral correction amount (I minutes) increases until the actual position exceeds the target position, the actual position is larger than the target position by this large integral correction amount (I minutes). It will overshoot significantly.

The integral correction amount (I minute) is necessary to absorb the steady-state deviation, but it causes overshoot in the transient state. In view of such conventional problems, it is an object of the present invention to prevent overshoot due to the integral correction amount when the target position changes in steps and improve controllability.

[0010]

Therefore, in the invention according to claim 1, the position control device is constructed as shown in FIG. This position control device includes a target position setting means for setting a target position of the controlled object, an actual position detection means for detecting an actual position of the controlled object, an actuator for driving the controlled object, a target position and an actual position. A deviation calculating means for calculating a deviation, a proportional correction amount calculating means for calculating a proportional correction amount proportional to the deviation, an integral correction amount calculating means for integrating the deviation to calculate an integral correction amount, It is premised that a control amount calculation means for calculating the control amount for the actuator based on the sum of the proportional correction amount and the integral correction amount is provided.

Further, there is provided an integral correction amount reducing means for reducing the integral correction amount calculated by the integral correction amount calculating means when the deviation is large. In this case, when the target position changes stepwise and the deviation between the target position and the actual position becomes large, a large proportional correction amount is generated and the actual position can be brought close to the target position. On the other hand, since the integral correction amount decreases, it is possible to prevent overshoot due to the integral correction amount when the actual position approaches the target position.

In the state where the deviation is small, the integral correction amount becomes the usual amount, so that the steady deviation can be absorbed. In the invention according to claim 2, the integral correction amount calculating means calculates the integral correction amount by integrating the product of the deviation and the integral gain, and the integral correction amount reducing means comprises: The integral gain is determined according to the absolute value of the deviation so that the integral gain becomes smaller as the absolute value of the deviation increases.

As described above, the larger the deviation is, the smaller the integral gain by which the deviation is multiplied can make the integral correction amount relatively large in the large deviation. The shoot can be effectively prevented. In the invention according to claim 3, the integral correction amount reducing means prohibits the integral by the integral correction amount calculating means when the absolute value of the deviation is equal to or larger than a predetermined value. .

As described above, when the deviation is equal to or larger than the predetermined value,
If the calculation of the integral correction amount is prohibited, the integral correction amount does not increase when the deviation is large, and thus the overshoot due to the integral correction amount can be reliably prevented.
In the invention according to claim 4, the actuator introduces hydraulic pressure into the hydraulic cylinder that drives the controlled object and one chamber of the hydraulic cylinder in the ON state, and introduces hydraulic pressure into the other chamber of the hydraulic cylinder in the OFF state. And a solenoid valve.

In the case of this system, the position of the object to be controlled can be controlled by driving the solenoid valve by duty and controlling the duty. According to a fifth aspect of the present invention, in the system of the fourth aspect of the invention, the control amount calculating means adds a correction duty based on the sum of the proportional correction amount and the integral correction amount to the basic duty of 50%. Then, the control duty to the solenoid valve is calculated.

In the case of the above system, the basic duty is 50%
Since it is in a neutral state, the sum of the proportional correction amount and the integral correction amount is added as a correction duty (if the sum is a negative value, it is practically subtracted) to obtain the control duty. Just ask. In the invention according to claim 6, the control target is a variable valve mechanism that variably controls the opening / closing timing of intake and exhaust valves of the internal combustion engine.

As a result, the open / close timing of the intake / exhaust valve of the internal combustion engine can be accurately controlled to improve drivability.

[0018]

Embodiments of the present invention will be described below. The system configuration of the position control device is as shown in FIG. In the present embodiment, the control unit 4 of FIG. 2 performs arithmetic processing according to the flowchart of FIG.

The position control routine shown in the flowchart of FIG. 3 will be described. It should be noted that this routine is executed at predetermined time intervals (for example, 10 ms). Step 1 (S in the figure
It is written as 1. In the following), the target position XT is set. For example, in the variable valve mechanism of the internal combustion engine, the target position XT of the valve timing control member (the tip of the output rod 1a) is set by referring to the map from the engine speed and the load. This portion corresponds to the target position setting means.

In step 2, the position sensor 5 detects the actual position XA. This portion corresponds to the actual position detecting means together with the position sensor 5. In step 3, the actual position XA is subtracted from the target position XT, and the deviation ΔX = XT−X
Calculate A. This part corresponds to the deviation calculating means. In step 4, the deviation ΔX is multiplied by a predetermined proportional gain Gp to calculate a proportional correction amount P = Gp · ΔX. This portion corresponds to the proportional correction amount calculation means.

In step 5, the integral gain Gi is set by referring to the table from the absolute value of deviation | ΔX |. Here, the integral gain Gi is made smaller as the absolute value of deviation | ΔX | is larger. Further, the integral gain Gi is made smaller than the proportional gain Gp. In step 6, the deviation ΔX is multiplied by the integral gain Gi and added to the integral correction amount I up to the previous time to calculate the integral correction amount I = I + Gi · ΔX. This portion corresponds to the integral correction amount calculation means.

Here, when the deviation ΔX is large, the integral gain Gi is reduced in step 5, so the integral correction amount I is reduced. Therefore, step 5 corresponds to the integral correction amount reducing means. In step 7, the proportional correction amount P and the integral correction amount I are added to calculate a correction amount (correction duty) PI = P + I.

In step 8, the correction duty PI is added to the basic duty 50% to calculate the control duty DUTY = 50 + PI as the control amount. This part corresponds to the control amount calculation means. Then, in step 9, the solenoid valve 2 is driven based on the control duty DUTY.

In this case, when the target position XT changes stepwise and the deviation ΔX between the target position XT and the actual position XA becomes large, a large proportional correction amount P is generated, and the actual position XA.
Can be brought close to the target position XT. On the other hand, with respect to the integral correction amount I, the larger the deviation ΔX is, the smaller the integral gain Gi becomes and the more the actual position XA decreases.
It is possible to prevent the overshoot from being caused by the integral correction amount I when is approaching the target position XT.

In the state where the deviation ΔX is small, the integral correction amount I becomes almost as usual, so that the steady deviation can be absorbed. Next, another embodiment will be described. The system configuration of the position control device is the same, and in this embodiment, arithmetic processing is performed according to the flowchart of FIG.

The position control routine shown in the flowchart of FIG. 4 will be described. It should be noted that this routine is also executed at predetermined time intervals. Steps 1 to 4 are the same. In step 5 ', it is determined whether or not the absolute value of deviation | ΔX | is equal to or larger than a predetermined value. If | ΔX | <predetermined value, step 6
To the deviation ΔX and a predetermined integral gain Gi (where Gi
<Gp) is multiplied and this is added to the integral correction amount I up to the previous time to calculate the integral correction amount I = I + Gi · ΔX.
This portion corresponds to the integral correction amount calculation means.

On the other hand, when | ΔX | ≧ predetermined value,
Do not execute step 6. At this time, the integrated correction amount I is held at the previous value. As described above, when the deviation ΔX is large, the integral correction amount I is not increased because the integral correction amount is not calculated (deviation integration) in step 6 in the determination in step 5 ′. Therefore, the step 5'corresponds to the integral correction amount reducing means.

Steps 7-9 are the same. In this case, when the target position XT changes stepwise and the deviation ΔX between the target position XT and the actual position XA becomes large, a large proportional correction amount P is generated to bring the actual position XA closer to the target position XT. it can. On the other hand, with respect to the integral correction amount I, when the deviation ΔX is large, the calculation of the integral correction amount I is prohibited and substantially decreases, so that the actual position XA
It is possible to prevent the overshoot from being caused by the integral correction amount I when is approaching the target position XT.

When the deviation ΔX is small, the integral correction amount I becomes the normal value, so that the steady deviation can be absorbed.

[0030]

As described above, according to the invention of claim 1, when the deviation is large, the integral correction amount is decreased, so that the integral correction amount causes an overshoot. It can be prevented and the controllability can be improved. According to the second aspect of the present invention, the integral gain is adjusted to reduce the integral correction amount, so that the overshoot due to the integral correction amount can be effectively prevented.

According to the third aspect of the present invention, since the integral correction amount is reduced by prohibiting the integral, it is possible to reliably prevent the overshoot due to the integral correction amount. According to the invention of claim 4, the solenoid valve is duty-driven,
By controlling the duty, the position of the controlled object can be controlled. According to the fifth aspect of the invention, the neutral state is achieved at the basic duty of 50%, so that the control can be performed in consideration of this.

According to the sixth aspect of the invention, by applying the variable valve mechanism of the internal combustion engine, it is possible to accurately control the opening / closing timing of the intake / exhaust valve and improve the drivability.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing a configuration of the present invention.

FIG. 2 is a system diagram of an embodiment of the present invention.

FIG. 3 is a flowchart of a position control routine

FIG. 4 is a flowchart of a position control routine showing another embodiment.

FIG. 5 is a diagram showing a conventional problem.

[Explanation of symbols]

 1 Hydraulic cylinder 2 Solenoid valve 3 Oil pump 4 Control unit 5 Position sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G05D 3/12 G05D 3/12 E 305 305V 305L

Claims (6)

[Claims] 1. A position control device, comprising an actuator for driving a controlled object, for controlling the position of the controlled object, comprising: a target position setting means for setting a target position of the controlled object; and an actual position of the controlled object. The actual position detecting means, the deviation calculating means for calculating the deviation between the target position and the actual position, the proportional correction amount calculating means for calculating the proportional correction amount proportional to the deviation, and the deviation are integrated and integrated. A deviation correction amount calculating means for calculating a minute correction amount, and a control amount calculating means for calculating a control amount for the actuator based on a sum of a proportional correction amount and an integral correction amount. The position control device is provided with an integral correction amount reducing means for reducing the integral correction amount calculated by the integral correction amount calculating means when the value is large. 2. The integral correction amount calculating means calculates the integral correction amount by integrating the product of the deviation and the integral gain, and the integral correction amount reducing means calculates the integral correction amount. 2. The position control device according to claim 1, wherein the integral gain is determined according to the absolute value of the deviation so that the integral gain becomes smaller as the absolute value increases. 3. The integral correction amount reducing means prohibits integration by the integral correction amount calculating means when the absolute value of the deviation is equal to or larger than a predetermined value. The position control device described. 4. The actuator includes: a hydraulic cylinder for driving a controlled object; and a solenoid valve for introducing a hydraulic pressure into one chamber of the hydraulic cylinder in an ON state and introducing a hydraulic pressure into the other chamber of the hydraulic cylinder in an OFF state. 4. The position control device according to claim 1, wherein the position control device comprises: 5. The control duty calculation means is configured to have a basic duty of 50.
5. The position control device according to claim 4, wherein a correction duty based on the sum of the proportional correction amount and the integral correction amount is added to%, and the control duty to the solenoid valve is calculated. . 6. The position according to claim 1, wherein the controlled object is a variable valve mechanism that variably controls opening / closing timings of intake / exhaust valves of an internal combustion engine. Control device.