JP2000330607A - Control device for control system with dead time - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To estimate an appropriate estimated state quantity for a control system having a dead time, and to appropriately control the control system using the estimated state quantity. A state estimator obtains an estimated state amount by inputting a current operation amount and a feedback amount for correcting an error between an actual state amount and an estimated state amount. As the estimated state quantity output from the state estimator, a value obtained by considering a dead time factor and a value calculated based on an actual state quantity are used. Specifically, a value calculated using the estimated state amount sampled several times before is set as a feedback amount. As a result, it is possible to estimate an appropriate estimated state quantity for a control system having a dead time, and to calculate a switching plane σ based on the estimated state quantity and switch the value of the operation amount to thereby make the control system appropriate. Can be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a control device for a control system having a dead time, and more particularly to a control device for controlling a control system having a dead time using an estimated state quantity from an observer.

[0002]

2. Description of the Related Art Conventionally, as this type of control device, there has been proposed a device which performs a sliding mode control on an air-fuel ratio control system of an engine using an estimated state quantity from an observer (for example, "An Observer"). -Based Controll
er Design Method for Automotive Fuel-Injection Sys
tems '' Proceeding of the American Control Conferen
ce San Francisco, California, June 1993).
This control device performs the sliding mode control using the estimated state value from the observer, thereby causing a problem caused by performing the sliding mode control without using the observer, that is, the responsiveness required by the air-fuel ratio control system of the engine. It is described that chattering that occurs based on a dead time that is too long to be ignored can be prevented. Note that the observer estimates the state estimation amount by multiplying the deviation information between the estimated state amount and the actual state amount by an appropriate gain and feeding it back.

[0003]

When the sliding mode control method is applied to a control system characterized by the existence of a large dead time, such as a shift control system of an automobile transmission, there is a problem that the robustness is greatly reduced. Was. FIG. 6 shows a temporal change in the rate of change of the rotational speed and a temporal change in the rotational speed as a simulation result when a normal sliding mode control method is applied. As shown in FIG. 6, the actual value of the state quantity cannot properly follow the target value only by applying the ordinary sliding mode control method.

[0004] In order to solve such a problem, it is possible to consider the use of an observer as in the case of the above-described air-fuel ratio control system of the engine. However, in this method, the observer is configured by a simple addition of a linear term and a non-linear term, and the observer cannot be applied to a controlled object that does not conform to the configuration by this addition, and the dead time due to a time delay of the air-fuel ratio sensor. Because it considers only the dead time determined by a single factor, and does not consider the dead time that is complicatedly determined by multiple factors, it is not possible to estimate an accurate state quantity, Appropriate control cannot be performed. As a simulation result when the sliding mode control method is applied using the target value as the estimated state quantity, FIG. 7 shows the time change of the rate of change of the rotational speed and the time change of the rotational number as the estimated state quantity. FIG. 8 shows a temporal change in the rate of change of the rotational speed and a temporal change in the rotational speed as a simulation result when the sliding mode control method is applied using the actual values. As shown in FIGS. 7 and 8, even when the sliding mode control method is applied using the target value or the actual value of the state quantity as the estimated state quantity,
The actual value of the rate of change of the rotational speed around 1.25 seconds drops significantly from the target value, giving a shock as a bodily sensation, making it impossible to perform appropriate control.

[0005] It is an object of the control apparatus for a control system having a dead time according to the present invention to appropriately control a control system having a dead time. Another object of the present invention is to provide a control system for a control system having a dead time, which estimates an appropriate estimated state quantity for a control system having a dead time.

[0006]

Means for Solving the Problems and Functions and Effects The control device of the control system having a dead time according to the present invention employs the following means in order to achieve at least a part of the above object.

A control device for a control system having a dead time according to the present invention is a control device for controlling a control system having a dead time by using an estimated state quantity from an observer. , Based on the actual state quantity, the manipulated variable, and the estimated state quantity estimated a predetermined time before the estimation.

In the control device according to the present invention, the estimated state quantity is estimated in consideration of the dead time by estimating the estimated state quantity based on the estimated state quantity estimated a predetermined time before the current estimation time. Can be. Here, the “estimated state amount estimated before the predetermined time” includes any one of the estimated state amounts estimated before the estimated state amount estimated immediately before, and a plurality of estimated state amounts. The quantity is also included.

In the control device according to the present invention, the observer may estimate the estimated state quantity while correcting a parameter of the control model based on a dead time. By doing so, a more appropriate estimated state quantity can be estimated according to the size of the dead time, whereby the control target can be more appropriately controlled.

In the control device according to the present invention, the control may be performed by a sliding mode control method. In this way, it is possible to enjoy the characteristic high robustness of the sliding mode control method.

Further, in the control device according to the present invention, the predetermined time may be set based on a dead time of a control system. By appropriately selecting the predetermined time according to the dead time, a more accurate estimated state quantity can be estimated, and thereby the control system can be appropriately controlled.

Alternatively, in the control device according to the present invention, the estimated state quantity estimated before the predetermined time may be sampled less frequently than the sampling frequency of the actual state quantity.

[0013]

Next, embodiments of the present invention will be described with reference to examples. FIG. 1 is a block diagram showing a configuration when the control device of the present invention is controlled by a sliding mode control method with an automatic transmission of a vehicle as a control target. As shown in the figure, in the control device of the embodiment, the state estimator (observer) inputs the current operation amount,
A feedback amount for correcting an error between the actual value of the state quantity and the estimated state quantity is input, and the estimated state quantity is obtained and output. This feedback amount is expressed as a value obtained by multiplying a gain by a deviation between an actual value of the state amount and an estimated state amount output from the state estimator in consideration of a dead time factor. Thus, an accurate estimated state quantity can be estimated by considering the dead time factor. In the sliding mode control, a switching plane σ is calculated based on the estimated state quantity and the target value output from the state estimator,
The value of the operation amount is switched based on the value of the switching surface σ. If the estimated state quantity is accurate, switching of the manipulated variable in the sliding mode control method is also accurate, and appropriate control can be performed.

A specific example of a control device for controlling the automatic transmission by estimating the estimated state quantity in consideration of the dead time factor will be described below. FIG. 2 is a block diagram of this specific example.
As shown in the following formulas (1) and (2), the system to be controlled is divided into a gear train system and a hydraulic system incorporating dead time, and a continuous-time model is zero-order held at a sampling period of sample tt. Was converted by Here, Xnt and Xx2 are state quantities,
Nt is the speed of the transmission, x2 is the hydraulic pressure, u
Is the manipulated variable. In addition, nk takes into account the dead time, and can be set to a constant multiple of the sample period in a discrete system. Note that Asysd and B in Expression (1)
sysd, Csysd, and Dsysd are coefficients of the gear train system model, and Ahyd and Bhy in equation (2) are used.
d, Chyd, and Dhyd are coefficients of the hydraulic system model.

[0015]

(Equation 1) The low-pass filter is used to remove high-frequency noise, and in a specific example, was configured by the following equation (3). Here, X_l is a state quantity, and u_l is an output (operating quantity) of the low-pass filter. In addition, A_l, B_l, C_l, and D_l in Expression (3) are coefficients of a low-pass filter.

[0016]

(Equation 2) As shown in the following formulas (4) and (5), the differentiator obtains a difference ΔNt between the previous value of the rotation speed Nt and a difference Δu between the previous value of the manipulated variable u_l passed through the low-pass filter. Things.

[0017]

(Equation 3) In the observer, as shown in the following equations (6) and (7), the deviation ΔNt of the rotation speed from the differencer and the deviation Δ
u, the deviation ΔNt ′ of the estimated rotational speed and the estimated rotational speed N
and t ′. Here, the first term ΔNt ′ (k−nk) in parentheses of the last term on the right side of the equation (6) is a term in consideration of the dead time, and is the value of the estimated rotational speed of the previous step by the value of nk. The deviation (deviation of the estimated state quantity) is used. This n
k can be set to a constant multiple of the sample period in the discrete system, similarly to the control target model. Note that Aobd, Bobd, and L in Equation (6) are observer coefficients.

[0018]

(Equation 4) In the sliding mode control, the switching surface σ is calculated by the following equation (8) using the target value r and the decrease amount Δr of the target value, the estimated rotation speed Nt ′ from the observer, and the deviation ΔNt ′ of the estimated rotation speed, Based on the calculated value of the switching surface σ, the operation amount is switched by the equation (9). Target value r
And the reduction amount Δr of the target value are calculated by using the equations (10) and (1
1). Note that S1 and S in equation (8)
2. In Equation (9), γ and η are gains in the sliding mode control, and Koubai in Equations (10) and (11) is a decrease amount of the target value per one step of the sampling time.

[0019]

(Equation 5) When the simulation is performed using the coefficients shown in Table 1 below and the values shown in Table 2 as initial values, the results are shown in FIG. As shown in the figure, the rate of change of the rotational speed is around the target value both in the estimated value and the actual value, but the rotational speed Nt is slightly higher than the target value and decreases in the same manner as the decrease in the target value. It can be understood that the control is appropriately performed as compared with the conventional example shown in FIG.

[0020]

[Table 1]

[Table 2] As described above, according to the control device of the embodiment described using the specific example, the estimated amount of state is estimated in consideration of the dead time, and the operation amount obtained by using the estimated amount of state is output, whereby a large dead time is generated. A control system having time can be appropriately controlled.

In the specific example of the embodiment, the dead time in the observer is updated for each step. However, the dead time may be updated every several steps. For example, in the case of updating once every four steps, the parentheses in the last term on the right side of the equation (6) are the following equation (12)
ΔNt ′ (k ′) − ΔNt using k ′ calculated by
(K '). Here, [k /
4] means a quotient obtained by dividing k by 4. For example, when k is 1, 2, 3, 4, and 5, [k / 4] is 0, 0,
0,1,1 and k 'is 0,0,0,4,4 because this [k / 4] is multiplied by four.

K ′ = 4 · [k / 4] (12) Such a control is performed by a loop fed back from the manipulated variable u in FIG. 1 with a sampling time as short as possible for the sliding mode control.
This means that the loop for correction fed back from the actual state quantity only needs to be a sampling period capable of realizing the responsiveness required of the feedback control system.

In the embodiment, the control device of the present invention has been described using a specific example using the sliding mode control method.
A method that does not use the sliding mode control method may be a specific example. For example, the optimal regulator control may be used. FIG. 4 shows a block diagram in this case.
The following equation (13) may be used for the feedback output, that is, the operation amount u, instead of the equation (9). Here, Kc is a coefficient. Expressions other than Expressions (8) and (9) are the same in this optimal regulator control.

U = −Kc · ΔNt ′ (k + 1) (13) A specific example of the optimal regulator control using the initial value in Table 2 using only the observer coefficient L in Table 1 changed to 0.12 When we simulate,
The result is as shown in FIG. As can be seen from the simulation results, the rate of change of the rotation speed ΔNt and the estimated value ΔNt ′ change in the vicinity of the target value, and the rotation speed Nt is slightly higher than the target value and changes in the same manner as the target value. It can be understood that the control is appropriately performed as compared with the conventional example shown in FIGS.

That is, the control device of the embodiment is not only effective when the sliding mode control method is applied, but is also effective when applied to other controls, for example, optimal regulator control. is there.

The embodiments of the present invention have been described with reference to the embodiments. However, the present invention is not limited to these embodiments, and various embodiments may be made without departing from the scope of the present invention. Of course, it can be carried out.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration when a control device of the present invention is controlled by a sliding mode control method with an automatic transmission of an automobile as a control target.

FIG. 2 is a block diagram showing a specific example of a configuration when the automatic transmission is controlled by a sliding mode control method.

3 is a graph illustrating a time change of a rate of change of a rotation speed and a time change of a rotation speed as a simulation result of the specific example of FIG. 2;

FIG. 4 is a block diagram showing a specific example of a configuration when the automatic transmission is controlled by optimal regulator control.

FIG. 5 is a graph illustrating a time change of a rate of change of a rotation speed and a time change of a rotation speed as simulation results of the specific example of FIG. 4;

FIG. 6 is a graph showing a temporal change in a rate of change of the rotational speed and a temporal change in the rotational speed as a simulation result when a normal sliding mode control method is applied.

FIG. 7 is a graph showing a temporal change in a rate of change of a rotational speed and a temporal change in a rotational speed as a simulation result when a sliding mode control method is applied using a target value as an estimated state quantity.

FIG. 8 is a graph showing the time change of the rate of change of the rotational speed and the time change of the rotational speed as a simulation result when the sliding mode control method is applied using the actual value of the state quantity as the estimated state quantity. .

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuji Murakishi 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside of Toyota Central R & D Laboratories Co., Ltd. 41, Yokomichi, Toyota Central Research Laboratory Co., Ltd. (72) Inventor Toshinari Suzuki 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Katsumi Kawano 1 Toyota Town Toyota City, Aichi Prefecture Toyota F-term (Reference) 3J052 AA04 AA19 CA31 FA01 FB31 LA01 5H004 GA10 GA17 HA08 HB08 JB15 JB24 KA32 KA35 KA72 KA74 KB38 KC17 KC28 LA03 LA12 MA12 9A001 BB06 HH34 JJ77 KK54

Claims (2)

[Claims] 1. A control device for controlling a control system having a dead time by using an estimated state quantity from an observer, wherein the estimation of the estimated state quantity by the observer includes an actual state quantity, an operation amount, and the estimation time. A control device, wherein the control is performed based on an estimated state quantity estimated before a predetermined time. 2. The control device according to claim 1, wherein the observer estimates the estimated state quantity while correcting a parameter of the control model based on a dead time.