JPH02151571A - Vehicle motion estimating device - Google Patents

Abstract

PURPOSE:To enable at least two condition quantities to be estimated in good accuracy by performing the correction corresponding to a road surface in its cross direction tilt being based on the deviation of an estimating value from the detecting value in cross angular acceleration serving as the output amount of a vehicle motion system. CONSTITUTION:A steering angle detecting means A and a car speed detecting means B are provided, and their detecting information is input to a motion estimating arithmetic means C. Here being based on a vehicle model described in an equation of motion, an estimating amount of at least two condition quantities and an estimating value of cross acceleration of a vehicle generated in its cross direction are estimated and calculated. While a cross acceleration detecting means D, directly detecting the cross acceleration, is provided, and being based on the deviation of a detecting value from the estimating value in the cross acceleration, leading particulars of the vehicle and the aerodynamic characteristic of the vehicle, a disturbance correcting means E corrects an error of a condition quantity estimating value of the motion estimating arithmetic means C generated by tilting of a road surface in its cross direction. And in accordance with the condition quantity estimating value after this correction, the information can be utilized for a steering angle control and/or a suspension control.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vehicle motion estimation device for estimating the state quantities of a vehicle system, such as the yaw rate (yaw angular velocity) and lateral velocity of the vehicle. This device is suitable for applying the state quantity estimated by the device as input information to a steering angle control device, an active suspension, or the like.

[Conventional technology]

Conventionally, as a device for controlling the motion characteristics of a vehicle using state quantities such as the vehicle's yaw rate and lateral speed, there is, for example, Japanese Patent Application Laid-Open No. 62-241772. The device described in Publication No. 62241773 (both names of the invention are "actual steering angle control device for vehicle")
)It has been known.

These actual steering angle control devices command and control the steering angle so as to follow the target value of the motion state quantity obtained from a reference model that is a mathematical model of the characteristic of the motion state quantity of the own army. When taking lateral acceleration as the motion state quantity to be tracked, in addition to the lateral acceleration sensor for output feedback, a sensor for state feedback is used.
It was necessary to install a yaw rate sensor (rate gyro) to detect yaw rate and a lateral speed sensor (ground vehicle speedometer) to detect lateral speed.

However, the above-mentioned yaw rate and lateral speed occur in small amounts and are easily affected by disturbances such as crosswinds and road slopes, so the rate gyro and ground vehicle speed meter used to detect them require high detection accuracy. This makes them expensive, and their large size makes them difficult to handle. For this reason, the cost required for manufacturing and installing the control device increases significantly, and it has been practically difficult to mount a device using each of the above-mentioned sensors on a general vehicle.

Therefore, in Japanese Patent Application No. 63-197776, the present applicant proposed a gain matrix that is set based on a mathematical model regarding planar motion of the vehicle using detected values from relatively inexpensive steering angle sensors, lateral acceleration sensors, etc. By an observer with
An estimation device for estimating yaw rate and lateral velocity is proposed.

[Problem to be solved by the invention]

However, the above-mentioned estimation device has an unresolved problem that when the road surface slopes laterally, the slope causes errors in the estimated values of yaw rate and lateral speed relative to the actual values. was there.

This invention was made in view of the unresolved problems of the prior art and the prior art, and it is based on the deviation between the detected lateral acceleration value and the estimated lateral acceleration value, and corrects the lateral inclination of the road surface. The first problem to be solved is to perform state quantity estimation calculations so that the state quantities can be estimated with high accuracy, and to maintain a low-cost configuration that can be mounted on general vehicles. The second problem is to estimate the lateral inclination angle of the road surface (hereinafter simply referred to as "inclination angle" as necessary) and to make the estimated value usable for controlling vehicle motion.

[Means to solve the problem]

In order to solve the above first problem, claim (1) of this invention
) to (4), as shown in FIG. 1(a), the device includes a steering angle detection means for detecting at least the steering angle of the front wheels, a vehicle speed detection means for detecting the vehicle speed, and information detected by both of the detection means. and a motion estimation calculation means for estimating the estimated values of at least two state quantities and the estimated value of the lateral acceleration occurring in the lateral direction of the vehicle based on the vehicle model described by the equation of motion. lateral acceleration detection means for directly detecting acceleration; and calculation of the motion estimation caused by the lateral inclination of the road surface based on the deviation between the lateral acceleration detected by the lateral acceleration detection means and the lateral acceleration estimated by the motion estimation calculation means. and disturbance correction means for correcting an error in the state quantity estimated value of the means.

In addition, in order to solve the second problem, the claims of this invention (
5), (6) As shown in FIG. 1(b), the device described above has the above-described configuration, and calculates the lateral inclination angle of the road surface based on the deviation Ect between the estimated lateral acceleration value a and the detected lateral acceleration value α. An inclination angle estimation calculation means for calculating η is added.

[Effect]

In the apparatus according to claims (1) to (4) of the present invention, the motion estimation calculation means inputs a steering angle and a vehicle speed, and generates estimated values of at least two state quantities based on a vehicle model described by an equation of motion. and an estimated value of the lateral acceleration as an output quantity, and the lateral acceleration detection means detects the actual value of the lateral acceleration.

Therefore, the disturbance correction means corrects the assumption error of the state quantity estimated value in the motion estimation calculation means caused by the slope in the lateral direction of the road surface, based on the deviation between the detected value of the lateral acceleration and its estimated value.

Further, in the apparatus according to claims (5) and (6), in addition to the above-mentioned operation, the inclination angle estimation calculation means estimates the inclination angle in the lateral direction of the road surface.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 2 to 4.

FIG. 2 is a block diagram showing the vehicle motion estimation device 2. As shown in FIG. In the figure, the vehicle motion estimation device 2 includes a lateral acceleration sensor 4. It has a vehicle speed sensor 6, a steering angle sensor 8, and an estimation calculator 10.

Among these, the lateral acceleration sensor is installed at the center of gravity of the vehicle,
The acceleration generated in the lateral direction of the vehicle at this center of gravity is detected and a lateral acceleration signal α corresponding to the acceleration is output to the estimation calculator IO. Further, the vehicle speed sensor 6 outputs a vehicle speed signal (2) corresponding to the vehicle speed, and the steering angle sensor 8 outputs a steering angle signal (theta) corresponding to the steering angle with respect to the front wheels to the estimation calculator 10, respectively.

Furthermore, the estimation calculator 10 includes signal processing circuits 12a to 12.
c. Microcomputer 14. D/A converter 16a-
16c, and amplifiers 1a to 18c. Among these, the signal processing circuits 12a to 12c are connected to each sensor 4.6.
．． The detection signals α, ■, and θ outputted from 8 are subjected to filtering processing and digital conversion processing, respectively.
Each processed signal is sent to the subsequent microcomputer 1.
It is designed to output to 4. The microcomputer 14 reads the processed signals α, ■, and θ, and estimates the state quantities, yaw rate ψ and lateral velocity ■, with corrections made for the slope in the lateral direction of the road surface.
The tilt angle η is estimated, and each estimated value is outputted via the subsequent D/A converters 16a to 16c and amplifiers 18a to 18c.

The microcomputer 14 of this embodiment functionally constitutes an estimation mechanism including a same-dimensional observer, and performs the above-mentioned estimation calculation using this.
It is as shown in the figure.

That is, in the figure, 20 is a vehicle model, and in this embodiment, the state quantities yaw rate l, lateral velocity 9y, and the measured output quantity of the vehicle motion system lateral acceleration 2 are estimated. 22 is a subtracter which calculates the deviation E, (=α-a) between the detected lateral acceleration value α and the estimated lateral acceleration value a. 24 is a disturbance estimation/correction unit, which calculates the vehicle model 2 based on the deviation E.
The correction amount of 0 is determined, and the tilt angle η is calculated.

Among these, the vehicle model 20 includes a coefficient d, a coefficient vector B, and a system matrix A, each element of which is determined as described later.
(V), gain setter 2 that takes charge of the output vector C(V)
5 to 28, adders 29 and 30, and an integrator 31, and the matrix A(V) and vector C(V) are functions of the vehicle speed. Then, in the adder 29, a value Bθ obtained by multiplying the steering angle θ, which is an input variable, by the coefficient vector B is calculated.
, the state feedback amount A (V), and the correction amount F - E, which will be described later, are added together and output to an integrator 31, which integrates to obtain the large state amount. In addition, the other adder 3o adds the value C(V), which is the state quantity large multiplied by the output vector C(V), and the value d, which is the input quantity θ multiplied by the coefficient d, and outputs the result. The variable a is calculated.

As will be described later, the disturbance estimation/correction unit 24 includes a gain setter 32 that handles a gain vector F consisting of 2 rows and 1 column in which each element is determined, and a gain setter 32 that handles a gain vector F of 2 rows and 1 column in which each element is determined, and 5in-' (Ea
/'g). The output of the function generator 33 is the estimated force of the tilt angle, and the deviation E. The value FE multiplied by the gain vector F
, is the correction amount for the road surface slope.

Here, it will be explained that by configuring the estimation mechanism shown in FIG. 3, it is possible to eliminate errors in state quantity estimation even if the road surface has a lateral slope.

It will also be explained that the inclination angle can be estimated.

First, the equation of motion of the vehicle is shown below, based on a well-known linear two-degree-of-freedom model and taking into account the slope in the lateral direction of the road surface.

In other words, I2ψ=2 LF CF 2 LRCR...(2)
Mα=M (Q, 10vψ) =2 Cr + 2 CM +Mg-5inη...(
3) C,=eK,β,...
・(4) C* = K Rβ large
...(5) β1=(θ/N) −(v, −,
LF φ) /V ・(6) βR= (Vy +LR
ψ)/V (7). here,
Iz: Yaw moment of inertia ψ: Yaw angular acceleration, L
F: Distance between front wheels and center of gravity, LR: Distance between rear wheels and center of gravity 1M: Vehicle mass, α: Lateral acceleration, ! y translational acceleration in two directions, ■: vehicle speed, ψ: yaw rate), g: gravitational acceleration, η: road surface lateral inclination angle + CF' front wheel cornering force, CR: rear wheel cornering force,
eK: Equivalent cornering power of front wheels, N: Cornering power of rear wheels, βF = Front wheel tank slip angle, β8 is rear wheel machine slip angle, θ: Steering angle, N steering gear ratio.

vy: lateral speed, of which vehicle specifications and aerodynamic characteristics are known.

Therefore, the state variables are yaw rate ψ, lateral velocity V,
(state variable vector X (X d = [ψ ■, ])),
The state equation and output equation when the lateral acceleration α is selected as the number of outputs and the disturbance is the inclination angle η are expressed by the following equations.

■=AX+Bθ+F g-sinη...(8) cr=
cX+dθ+g−sinηm' (9) Here, A is a 2×2 system matrix, B is a 2×1 coefficient vector, and C
is a 1×2 output vector, d is a coefficient, and F is a 2×1 coefficient vector, where a++= 2 a1□=-2 a□=-2 azt= 2 (LF”e KF + LR ”KR) / 12(Ly
e KF LIIKll ) / 12(L, e K
F LRKII ) /M(e Ky + KR
) / M bll=2 Lye KF / 12bz+= 2
e Kr/M.

On the other hand, the state equation and output equation in the configuration shown in FIG.
However, E, = α-cx) cx = C father + dθ ... (11
). Substituting equations (9) and (II) into equation 00), ■ = A father and child Bθ1F (C (X - father) + g - s
iny+)...02). Assuming that 5<=x at a certain point (for example, when traveling straight), the θth equation becomes ■=A father and son Bθ+Fg−sinη − side,
It has the same form as the above equation (8), and even if the road surface slopes laterally, the relationship ``X'' is always satisfied.

That is, with the configuration shown in FIG. 3, it is theoretically possible to reduce the estimation error of the state quantity due to the inclination angle to zero.

By the way, the deviation EI:f of the output amount mentioned above is E, = α-
a=c (X-father)+g-sinη・(+4),
If father -
・“Q[i) is obtained, and the inclination angle η is determined.

Next, the overall operation of this embodiment will be explained.

The microcomputer 14 performs the estimation calculation operation based on the flowchart in FIG.
This is done by timer interrupt processing for each ec). That is, in step (2) in the figure, the lateral acceleration sensor 4. Vehicle speed sensor 6
, and the detection signals αIVI and θ from the steering angle sensor 8 are read in through the signal processing circuits 12a to 12c, and these values are temporarily stored as the lateral acceleration α, vehicle speed 2, and steering angle θ.

Next, the process moves to step (2), and by referring to the memory table, the system matrix A (V) corresponding to the value of the vehicle speed V is determined.
, create an output vector C(V).

Next, move on to step ■, father-5 intercourse di...
・Calculate Qη to calculate yaw rate ψ and lateral velocity V
.

The estimated value of the state variable vector X consisting of is calculated. Specifically, this operation is performed at the time of the previous operation, that is, (i-1)
Using the estimated value parent (i-1) of the time and the calculated value intersection (i-1), at the time of the current calculation, that is, the parent (i) of the i-th calculation, J(i) = (i-1) 10 At-φ(i-1)
...QB) Qy (i) = Qy (i-1) + Δt
-Q (i-1)... Calculate from the second of 0ω.

Next, the process moves to step (2), and the correction amount FE for the disturbance (road surface slope) is calculated using the gain vector F stored in advance.
and the deviation Ee at the (i-1)th calculation, and then proceed to steps ① to ②.

In step (2), based on the above-mentioned equation 00 and using the calculated value in step (2), an observer matrix (2) = A+Bθ+FE, x is created and calculated.

In step (2), an output matrix 6t=C+dθ is created and calculated based on the above-mentioned equation 01).

Furthermore, in step (2), formula E is calculated based on the above-mentioned formulas 04) and 06). =cx-a, η=sin-' (E,
/ g) to find the inclination angle η.

Next, the process moves to step (2), and the signal corresponding to the calculated value +Vy in steps (2) and (2) is sent to the D/A converter 16a=
16c and amplifiers 18a to 18C.

The above processing is repeated every time Δ, so by setting this calculation cycle Δt appropriately, the yaw rate ψ, lateral velocity ■, and inclination angle η can be calculated simultaneously in real time and on the lateral side of the road surface. Accurate estimation is possible without being affected by directional inclination. In addition, since this estimation device uses relatively low-cost parts to construct the estimation mechanism including the observer, it is not necessary to install an expensive rate gyro or ground vehicle speed meter as in the past, and the overall device is low-cost. It is low cost and can be easily installed in general vehicles.

Here, in this embodiment, the steering angle sensor 8. The signal processing circuit 12b and the processing in step (2) in FIG. , the signal processing circuit 12C, and the fifth
The lateral acceleration detection means is configured by the process of step (2) in the figure.

In addition, the processing of steps ■, ■, ■, ■, ■ in FIG.
A motion estimation calculation means is configured. Furthermore, the processing in steps (2) and (2) in FIG. .

In the above embodiment, if it is desired to accurately estimate only the large state quantity without estimating the tilt angle disturbance value η, the function generator 33 may be removed.

In addition, the above explanation was about the case where the vehicle model was described as a continuous system, but as shown in the functional block diagram of Fig. 5 (the same symbols are used for the same components as in Fig. 3), If the estimation is based on a vehicle model described in a time system, the estimation accuracy can be improved. In that case,
Each matrix set by the gain setter 27.26.32 is A,=e^"' r BD "'(e^"'
-I)A-'B.

FD= (e"'t-I ]A-'F (e is the base of the natural logarithm, Δt is the sampling period). In addition, Z-1 in Fig. 5 means a delay of one sample, and I is the unit. It's a queue.

Furthermore, in a four-wheel steering vehicle, by considering the rear wheel actual steering angle δ in addition to the front wheel steering angle θ as an input (for example, "Model following control and four-wheel steering vehicle", automotive technology,
Vol, 42. No. 3.1988, pages 304-310), it can be constructed in exactly the same manner as the above embodiment.

In addition to the yaw rate and lateral velocity described above, the estimated state quantity in the above embodiment may be the yaw rate and the center of gravity inspection slip angle, or may be a combination of three or more state quantities as necessary. You can.

Furthermore, the inclination angle estimation calculation means of the embodiment described above may be provided only when necessary.

Furthermore, although the estimation arithmetic unit 10 in the embodiment described above is composed of an analog electronic circuit and a microcomputer, it may be composed entirely of an analog electronic circuit or a microcomputer.

〔Effect of the invention〕

As explained above, claims (1) to (4) of this invention
In the described device, a correction is made to counter the inclination in the lateral direction of the road surface based on the deviation between the estimated value of the lateral acceleration as an output quantity of the vehicle motion system and its detected value, and at least two state quantities (for example, yaw rate and Since the lateral velocity (at the center of gravity) is estimated, even if there is such a slope, an accurate state quantity can be estimated that eliminates the estimation error of the state quantity due to the disturbance, unlike the method described in the previous application. In addition to improving the control characteristics of the steering angle control device and active suspension that control using these estimated values, the system also maintains a low cost because it does not use expensive sensors like conventional ones. This has the advantage that it can be easily mounted on general vehicles.

Among these, in particular, the device according to claim (2) uses the detection signal of a lateral acceleration sensor, which is available at a relatively low cost, when determining the lateral acceleration as an output quantity, so signal processing is easy. , the cost of the entire device can also be reduced. Furthermore, since the apparatus according to claim (4) uses a correction method that is relatively easy to handle, there are advantages such as a simple estimation program.

Furthermore, in the apparatus according to claims (5) and (6), since a means for estimating the inclination angle is added to the configuration according to claim (1), it is possible to eliminate the influence of the disturbance on the estimation of the state quantity. First, it becomes a highly versatile estimating device that can estimate the inclination angle itself, which is a disturbance, and use the estimated value for other controls.

[Brief explanation of the drawing]

1(a) and 1(b) are diagrams corresponding to the claims of the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a diagram of the microcomputer in FIG. 2. A block diagram showing the functions, Figure 4 is a schematic flowchart showing the processing by the microcomputer in Figure 2, and Figure 5 is a block diagram showing the functions of the microcomputer when the vehicle model is described in a discrete value system. It is a diagram. In the figure, 2 is a vehicle motion estimation device, 4 is a lateral acceleration sensor, and 6 is a vehicle motion estimation device.
1 is a vehicle speed sensor, 8 is a steering angle sensor, 12a to 12c are signal processing circuits, 14 is a microcomputer, 16a-1
6c is a D/A converter, and 18a to 18c are amplifiers.

Claims (6)

[Claims] (1) At least a steering angle detection means for detecting the steering angle of the front wheels, a vehicle speed detection means for detecting the vehicle speed, and at least two lateral acceleration detection means for directly detecting the lateral acceleration; and a lateral acceleration detection means for directly detecting the lateral acceleration. disturbance correction means for correcting an error in the state quantity estimated value of the motion estimation calculation means caused by a lateral inclination of the road surface, based on the deviation between the lateral acceleration detected value by the motion estimation calculation means and the lateral acceleration estimated value by the motion estimation calculation means; A vehicle motion estimation device comprising: (2) The lateral acceleration detection means has a lateral acceleration sensor that is provided at the center of gravity of the vehicle and detects lateral acceleration at the center of gravity, and the motion estimation calculation means is configured to estimate the lateral acceleration at the center of gravity of the vehicle. Claim (1)
The vehicle motion estimation device described. (3) The motion estimation calculation means is configured to estimate a yaw rate and a lateral velocity at the center of gravity, or a yaw rate and a lateral slip angle at the center of gravity, respectively, as state quantities.
1) Vehicle motion estimation device as described. (4) The disturbance correction means includes an estimated yaw rate ■, an estimated lateral speed ■_y, and an estimated state quantity vector ■(■^
T = [■ ■＿y]), steering angle θ, vehicle speed V, coefficient matrix A
, B, and the vehicle model is ■=A(V)■+Bθ, then ■=A(V)■+Bθ+KE_α E_α=α−■ Let KE_α be the correction amount for the lateral slope of the road surface, The vehicle motion estimating device according to claim (1), wherein the correction coefficient K is given by ▲a mathematical formula, a chemical formula, a table, etc.▼. (5) To the configuration described in claim (1) above, an inclination angle estimation calculating means for calculating the lateral inclination angle η of the road surface based on the deviation E_α between the estimated lateral acceleration value ■ and the detected lateral acceleration value α is added. A vehicle motion estimation device characterized by: (6) The inclination angle estimation calculating means is a means for calculating the inclination angle η using the formulas η=sin^-^1(E_α/g) and E_α=α−■, where gravitational acceleration is g. The vehicle motion estimation device according to item (5).