JPH0446829A - Speed control device for automobile - Google Patents

Abstract

PURPOSE:To improve the follow-up of target speed, and riding comfort by obtaining each feedback gain of a speed error and acceleration on the basis of an operation expression determined with the condition of an automobile for computing feedback amounts for the error and acceleration, and controlling the speed of the automobile on the basis of the feedback amounts. CONSTITUTION:An automobile speed error feedback amount is calculated from a speed control error Verr for actual speed Vact and target speed Vref, on the basis of a speed feedback gain Kev. Also, an acceleration feedback amount is calculated from actual acceleration alphaact on the basis of an acceleration feedback gain Kalpha. Then, a target acceleration alpharef is obtained from the speed error feedback and acceleration feedback amounts, and operation acceleration alphau is obtained with a primary delay filter 1/(1+ST). Target throttle valve opening and target brake fluid pressure are determined on the basis of a difference between the aforesaid operation acceleration alphau and actual acceleration alphaact.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a speed control device for an automobile, and particularly to a speed control device that performs optimal control to achieve both followability to a target vehicle speed and improvement of riding comfort.

(Prior Art) As a conventional speed control device for an automobile, there is known, for example, the one described in Japanese Patent Application Laid-open No. 191435/1983. This speed control device detects the throttle valve opening and actual vehicle speed, determines the intake air amount according to the target vehicle speed, and determines the fuel injection amount and throttle valve opening based on a predetermined calculation formula and optimal feedback gain. A feedback amount is determined for each of the feedback amounts, and the fuel injection amount and throttle valve opening are adjusted according to these feedback amounts.

(Problems to be Solved by the Invention) However, since the above-mentioned conventional speed control device for a vehicle merely controls the engine for the purpose of improving fuel consumption, the behavior of the vehicle lacks smoothness.
It is considered difficult to obtain high responsiveness.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a speed control device for a vehicle that allows the vehicle to behave smoothly and provide a good ride.

(Means for Solving the Problems) A speed control device for a vehicle according to the present invention detects the actual vehicle speed and actual acceleration, and determines a vehicle speed error feedback gain and an acceleration feedback gain from an arithmetic expression determined based on the state of the vehicle. , calculates the vehicle speed error feedback amount from the vehicle speed error and vehicle speed feedback cane, calculates the acceleration feedback amount from the actual acceleration and acceleration feedback gain, and calculates the valve opening of the throttle valve and brake fluid based on these vehicle speed feedback amounts and acceleration feedback amount. The key is to adjust the pressure.

(Function) The speed control device for a vehicle according to the present invention determines a vehicle speed error feedback gain and an acceleration feed gain using an arithmetic expression defined from the state of the vehicle, and calculates a vehicle speed error feedback amount using the vehicle speed error feedback gain and the vehicle speed error. Furthermore, since the acceleration feedback amount is calculated based on the acceleration feedback cane and the actual acceleration, and the vehicle speed is controlled based on these feedback amounts, it is possible to improve both the ability to follow the target vehicle speed and the ride comfort.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show a speed control device for an automobile according to an embodiment of the present invention, with FIG. 1 being a block diagram and FIG. 2 being a control block diagram.

As shown in FIG. 1, this vehicle speed control device includes a target acceleration generation section 11, an acceleration control section 12, and an actuator control section 13. Although not shown, a mileage sensor that detects the mileage; It has a vehicle speed sensor that detects the actual vehicle speed, an acceleration sensor that detects the actual acceleration, etc. The target acceleration generation section 11 and the acceleration control section 12 are composed of a microcomputer, etc., and the actuator control section 1
Reference numeral 3 includes a throttle motor that drives a throttle valve, a solenoid valve that adjusts brake fluid pressure, and a drive circuit that energizes the throttle motor and solenoid valve.

The target acceleration generation unit 11 manually receives signals representing the target route speed point sequence, etc., as well as signals representing the actual vehicle speed, actual acceleration, and actual travel distance from each of the above-mentioned sensors, and calculates the target acceleration from the Konerai No. 3. The signal representing the target acceleration is sent to the acceleration control unit 1.
Output to 2. The acceleration control unit 12 receives a signal representing the target acceleration as well as a signal representing the acceleration from the sensor, calculates et=throttle valve pressure from these signals, and generates a signal representing the target throttle valve opening and the target brake fluid pressure. The actuator control section 13
Output to. The actuator control unit 13 receives signals representing the current throttle valve opening and brake fluid pressure from the sensor, and controls the throttle valve opening to the target throttle valve opening and the brake fluid pressure to the target brake fluid pressure.

As shown in FIG. 2, this speed control device has an actual vehicle speed V
From the vehicle speed control error (vehicle speed error) verr between act and target vehicle speed Vr@f, vehicle speed feedback gain K@v
The vehicle speed error feedback amount is calculated based on the actual acceleration αact, and the acceleration feedback amount is calculated based on the acceleration feedback gain α.The target acceleration αref is determined from the vehicle speed error feedback amount and the acceleration feedback amount. The operation acceleration α is obtained by first-order lag fill ( ) from the target acceleration αref. Based on the control deviation of the acceleration between the operating vessel i+sT speed α and the actual acceleration αaCt, the target throttle valve opening and the target brake return pressure are determined, and the throttle motor and brake fluid pressure are controlled. Then, this speed control device performs optimal control and sets the above-mentioned vehicle speed feedback gain Ksv and acceleration feedback gain Ko as described later.

In the above explanation and FIG. 2, S represents the Laplace operator, and vehicle speed is expressed in units of Ln/h.
For acceleration, the unit is mG, and gravitational acceleration g is 9.8 m.
/sec2, the time constant T of the first-order lag filter is expressed in units of seconds.

By the way, in the optimal regulator theory, as is well known, the concept of an evaluation function is introduced, and control is performed so that this evaluation function takes the minimum value. Then, considering a -numerical linear system, the human force vector π, state vector 100, and output vector y of the controlled object are expressed by the following equation (1) (2
) is expressed by the state equation and output equation shown below.

dx → → Tv= A X + B u...' (1
)y=Cx... (2)
However, vector π 2. y is expressed as shown in the following equation, A is a system matrix, B is a human power matrix, and C is an output matrix, as shown in the following equation.

Here, assuming a closed-loop system as shown in Fig. 3 in which the human power vector 100 is replaced by the state vector 100 multiplied by the feedback matrix K, the evaluation for this closed-loop system is given by, for example, the following equation (3). The number of intervals J can be considered.

J=f,'(7TQp +T; TR 100) d t −
(3) However, Q and R are fixed symmetric matrices indicating weights, and are determined by simulation or the like.

Then, a feed pack matrix K that minimizes this evaluation function J is obtained by the following equation (4), and optimal control is performed using this feedback matrix K.

K=R−'B” P... (4) However, P is the only positive definite symmetric matrix solution of Riccati's equation in equation (5) below, and can be solved by the Potter method or Kleinman method, etc. can.

PA+ATP-PBR-'BTP+CTQC=O... (5) On the other hand, in this embodiment, the following equations (6), (7), and (8) are derived from FIG. 2 described above.

V err = V ref V act
... (8) (Note) g means gravitational acceleration.

And the operation acceleration α. Rewriting equation (6) using the ratio h (h-αact/αU) of the actual acceleration αact to is obtained.

Here, if the manipulated variable U and the state quantities x, ,
) By substituting into (10), the following equations (12) and (13) are obtained.

Above formula (12) (Representing 131 as a matrix, below formula (14)
The state equation shown in is obtained, and if the actual acceleration αIICt and vehicle speed error V err are selected as outputs, the following equation (1
The output equation shown in 5) is obtained.

However, intersection 1 = soil Σ" intersection 2 = ±" yr = dt
dt αact , y2 = V err.

Therefore, in this embodiment as well, the system matrix A and the human power matrix B correspond to the linear system described above (FIG. 3).
And the output matrix C is determined as shown in the following equations (18), (17), and (18).

Next, it is necessary to determine the evaluation function J, and the equation (
The matrices Q and R indicating the weights in 3) are expressed by the following formula (19) (
20), the following formulas (21) (22
), equations (23) and (24) are derived.

R= [rkou=u... (22) =Q+ 3'+"+q2 y2'... (
23) 5 Co T Rj Co = u [r Co U = ru
2... (24) Therefore, by substituting the above equations (23) and (24) into equation (3), the evaluation function J is determined as shown in equation (25), and equation (25) can be implemented as described above. In order to select the acceleration αact and the vehicle speed error V err as outputs, it is rewritten as shown in equation (26) below.

J” (q+y+'+q2y2'+ru')dt・
... (25) J=fo”(q+αact2+ q2V err+rα
r@f2)dt... (2
6) Then, calculate the feedback matrix K from the above equation (26) in the same way as the 8th lead from the above equation (3), and from this feedback matrix K, calculate the vehicle error speed feedback coefficient K ey and the acceleration feedback coefficient as the optimal values. α to
and seek.

Here, the coefficient 9 indicates the weight in equation (26).

Qz and r are determined by simulation or pole placement. For example, if it is based on simulation,
Coefficient q+, q2. Find a provisional value for r, solve Sockacchi's equation based on this provisional value to find the feedback matrix K, give appropriate initial values to the state quantities x, , x2, and calculate the output quantity (y
+, y2) by observing the response waveform, etc., and calculating the coefficient q
.

q2. By changing r, a value that yields a response waveform or an appropriate waveform is adopted.

In addition, the system matrix A changes depending on the state of the vehicle, such as the state of the driving road, the operating state of the engine, the state of the transmission, and the state of the brake system, but since local feedback is applied regarding acceleration, this The state of the car is the target operation acceleration α mentioned above. Since it can be expressed as the ratio of Otsumi acceleration αact to ,
It is also possible to calculate the feedback coefficients Kev and Kα for the ratio in advance and store them as a data table, detect the ratio, and change α to the feedback coefficients □ and □ according to the ratio. Also, these feedback coefficients Kev
, it is also possible to calculate α on-line according to the detected ratio.

Note that in the embodiment described above, the operation acceleration α. The gain of the transfer function of the controlled object, that is, the gain of the transfer function including the engine output characteristics, brake friction characteristics, and transmission transfer characteristics. By increasing , the operational acceleration and the actual acceleration can be considered to be the same value, and it is also possible to calculate α for the feedback coefficient, v, by setting the ratio of each of the above equations to 1.

(Effects of the Invention) As explained above, according to the vehicle speed control device for an automobile according to the present invention, the vehicle speed error feedback gain and the acceleration feedback gain are obtained from an arithmetic expression according to the state of the vehicle, and the vehicle speed error feedback gain and the vehicle speed The vehicle speed error feedback amount is calculated from the error, and the acceleration feedback amount is calculated from the acceleration feedback gain and the actual acceleration, and vehicle speed control is performed based on these feedback amounts, which improves tracking of the target vehicle speed and ride comfort. You can achieve both.

[Brief explanation of the drawing]

1 and 2 show a speed control device for an automobile according to an embodiment of the present invention, with FIG. 1 being a block diagram of the overall control system, and FIG. 2 being a control block diagram. FIG. 3 is a control block diagram in a general linear system. 11... Target acceleration generation section 12... Acceleration control section 13... Actuator control section

Claims (1)

[Claims] In addition to detecting the actual vehicle speed and actual acceleration, a vehicle speed error feedback gain and an acceleration feedback gain are determined from an arithmetic expression determined based on the state of the vehicle, and a vehicle speed error feedback amount is calculated from the vehicle speed error and vehicle speed error feedback gain. and an acceleration feedback gain, and calculates an acceleration feedback amount from the vehicle speed error feedback amount and acceleration feedback amount, and adjusts a valve opening degree of a throttle valve and a brake fluid pressure based on the vehicle speed error feedback amount and acceleration feedback amount.