JP2666527B2 - Vehicle state quantity estimation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention estimates a vehicle state quantity (e.g., a yaw rate and a lateral speed) of a vehicle accompanied by input noise from observation data including the noise. Related to the device.

(Prior Art) Conventionally, as a state estimator, for example, “Control System Design” (August 20, 1982; published by Maki Shoten), pages 126 to 1
The ones listed on page 29 are known.

This conventional source shows a Kalman filter which is a state estimator when the system includes noise.

In this Kalman filter, an input signal to be controlled and
Due to the deviation between the output signal of the control target model and the output signal of the control target, the noise component is removed from the output signal of the control target that is disturbed by system noise or observation noise, and the value from which the noise component has been removed is a true value. It is estimated as a state quantity.

(Problems to be Solved by the Invention) However, when such a state estimator is applied to a vehicle as it is, and the vehicle travels on a bad road with a state estimator taking noise corresponding to a good road into consideration, or vice versa, When traveling on a good road with a state estimator that considers considerable noise, the original function of the state estimator is not exhibited, and the noise becomes much larger than the true value or the true value There is a problem that the estimated value cannot follow the movement.

That is, when the output from the vehicle to be controlled is, for example, a yaw rate, and an inexpensive vibrating gyroscope is used as a sensor, depending on the road surface condition on which the vehicle is traveling, system noise (thrust disturbance from the road surface) or observation noise (signal Processing unit noise) is different.

The present invention has been made in view of the above-described problems, and in a vehicle state quantity estimating apparatus that estimates vehicle motion information of yawing and lateral motion based on predetermined observation data,
It is an object to estimate accurate vehicle motion information regardless of a road surface state on which a vehicle travels.

(Means for Solving the Problems) In order to solve the above problems, in the vehicle state quantity estimating apparatus of the present invention, the feedback gain in estimating the vehicle motion information of the yawing and the lateral motion is optimized according to the vehicle running road surface condition. Value.

That is, as shown in a frame correspondence diagram of FIG. 1, a front wheel steering angle detecting means a for detecting a steering wheel angle or a front wheel actual steering angle of a steering wheel, a vehicle speed detecting means b for detecting a vehicle speed, and a vehicle plane reading operation. Vehicle plane motion information detecting means c for detecting at least one component of the motion information
Road surface state detecting means d for detecting road surface information during traveling
A gain matrix e set based on a previously identified mathematical model of vehicle plane motion and road surface conditions;
And a signal from the front wheel steering angle detecting means e, the vehicle speed detecting means b, and the vehicle plane motion information detecting means c. A state quantity estimating operation unit g which calculates at least one vehicle motion information of yawing and lateral motion by a gain matrix determined by the gain matrix determining unit f and two or more integrators or an operation equivalent to integration. It is characterized by having.

(Operation) The operation when obtaining vehicle motion information of at least one of yawing and lateral motion will be described.

First, signals are input to the state quantity estimation calculation unit g from a front wheel steering angle detection unit a that detects a steering wheel angle or a front wheel actual steering angle of a steering wheel, and a vehicle speed detection unit b that detects a vehicle speed. A signal from the vehicle plane motion information detecting means c for detecting at least one of the motion information and the component of the plane motion is input as observation data.

On the other hand, in the estimation calculation unit gain matrix determination unit f, the value of the gain matrix e set based on the mathematical model of the vehicle plane motion identified in advance and the road surface state is used as road surface state detection means d for detecting road surface information during traveling. Is determined by this signal.

Then, in the state quantity estimation calculation unit g, the front wheel steering angle,
Each input signal of vehicle speed and vehicle plane motion information, the gain matrix determined by the estimation calculation unit gain matrix determination unit f, and two or more integrators or calculations equivalent to integration, at least one of yaw and lateral motion of the vehicle Exercise information is calculated.

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

 First, the configuration will be described.

FIG. 2 is a view showing a vehicle to which the vehicle state quantity estimating device of the embodiment is applied, wherein 1 is a vehicle speed sensor (vehicle speed detecting means) for detecting a vehicle speed, and 2 is a steering angle sensor for detecting a steering wheel angle of a steering wheel. (Front wheel steering angle detecting means) 3, a yaw rate sensor (vehicle plane motion information detecting means) for detecting a yaw rate while the vehicle is traveling, 4 a road surface state detecting sensor (a road surface state) for detecting a road surface state such as a good road or a bad road. Detecting means), 5 is an estimated yaw rate based on the input signals from the sensors 1, 2, 3, and 4 And estimated lateral speed (A gain matrix, an estimation operation unit, a gain matrix determination unit, and a good state estimation operation unit).

The vehicle speed sensor 1, the steering angle sensor 2, the yaw rate sensor 3,
The sensor signals from the road surface state detection sensor 4 are V,
θ, γ.

As the yaw rate sensor 3, an inexpensive vibration gyro or the like is used.

As the road surface state detection sensor 4, for example,
As described in Japanese Patent Application Laid-Open No. 60-151108 (Japanese Patent Application Laid-Open No. 59-8196), a frequency component corresponding to unsprung resonance and a frequency component corresponding to sprung resonance are obtained from vibration input to a vehicle from a road surface. Are individually taken out, and the road surface condition is determined based on the unsprung and sprung resonance frequency components.

FIG. 3 is a block diagram of a vehicle state estimating apparatus according to an embodiment, wherein the arithmetic processing unit 5 includes a gain model set based on a mathematical model of a vehicle plane motion identified in advance and a road surface state.
A feedback gain determination unit 52 for determining a feedback gain K, which is a value of the gain matrix 51, from a sensor signal ν from the road surface state detection sensor 4; a steering angle sensor 2, a vehicle speed sensor 1, and a yaw rate sensor 3 From the sensor signal θ, V, and the feedback gain K determined by the feedback gain determination unit 52 and the two or more integrators or an operation equivalent to integration, the yaw rate estimated value is calculated. Are simultaneously calculated.

 Next, the operation will be described.

First, the feedback gain The calculation method of will be described.

The equation of the two-degree-of-freedom plane motion of the vehicle is However, M; vehicle mass I _Z ; yaw moment of inertia L _f ; distance between front axis and center of gravity L _r ; distance between rear axis and center of gravity eK _F ; equivalent cornering power of front wheels K _R ; cornering power of rear wheels N; steering gear It is expressed as ratio.

In addition, thrust disturbance from the road surface (System noise) and the equation of motion taking into account the noise w (observation noise) of the signal processing unit mainly caused by this disturbance, However, v _f ; road surface disturbance input from the front wheels v _r ; road surface disturbance input from the rear wheels. Further, these noises are white noises having no correlation.

In consideration of its feasibility, the present apparatus uses a digital computer, and thus expresses the above equation (2) in a discrete time system.

However, Δt; sampling time The discrete-time Kalman filter has a configuration as shown in the following equation.

The error between the true value and the estimated value is as follows.

However, The covariance matrix of the estimation error is Becomes

Assuming that noise is white noise, Are independent of each other, the above equation (6) becomes as follows.

However, When the time limit is made infinite, the above formula becomes So, However, Becomes

In order to minimize the root mean square error E, it is necessary to partially differentiate Eq. (9) with k _ij so that ∂E / ∂k _ij = 0.

However, Here, in order for ∂E / ∂k _ij = 0 to hold for any X, Only. Therefore, Is obtained.

Then, by substituting equation (12) into equation (9) and rearranging, However, And the feedback gain is obtained by solving the stationary Riccati equation. Is found.

Therefore, the estimation calculation section feedback gain determination section 52, and the disturbance v _f, v _r push-up from the road surface is a system noise commensurate with the road surface condition detected by the road surface state detection sensor 4, advance vehicle experimental observation noise w The feedback gain K in each road surface state is calculated by the above equations (12) and (13).

FIG. 4 is a control block diagram of the state quantity estimation device of the embodiment.

FIG. 5 is a flowchart showing the flow of the state quantity estimation processing operation in the arithmetic processing unit 5 of the embodiment.

FIG. 6 shows the result of a simulation performed to confirm the effect.

Incidentally, since the simulation for good running shows the result when the vehicle is running straight (the steering angle is zero), the input signal relating to the steering angle is omitted in the figure.

The values of the coefficients used in the simulation are as follows: [vehicle] W = 1225 [kgf] I _Z = 200 [kgf · m · s ² ] L _f = 1.0 [m] L _r = 1.5 [m] eK _{F = 3750 [kgf / rad]} K R = 5000 [kgf / rad] N = 20 [ rough road _{noise] v f = 10.0 [kgf]} v r = 10.0 [kgf] w = 3.0 [deg / s] [ smooth road Noise] v _f = 1.0 [kgf] v _r = 1.0 [kgf] w = 0.02 [deg / s] In the conventional method, the feedback gain is a fixed value without detecting the road surface condition during traveling. Therefore, when traveling on a bad road with a good road gain, the estimated value is much noisier than the true value (4).
-2). Also, if you drive on a good road with bad road gain,
The variation of the true value is not accompanied by the estimated value, and the difference between the two values is large (4-3).

However, in the present invention, the magnitude of the system noise and the observation noise can be predicted by taking in the sensor signal ν from the road surface state detection sensor 4, so that a feedback gain suitable for the road surface state is selected, and the vehicle travels on a rough road. As can be seen from the simulation result (4-1) of the rough road gain and the simulation result (4-4) of the good road gain when traveling on a good road, the estimated value close to the true value is obtained regardless of the road surface condition. Obtainable.

Although the embodiments have been described with reference to the drawings, the specific configuration is not limited to the embodiments.

For example, by considering the term of the rear wheel steering angle in equation (1), which is the equation of motion of the two-degree-of-freedom vehicle model, the vehicle state quantity estimation device of the present invention can be applied to a four-wheel steering vehicle.

Further, in the apparatus of the embodiment, an example in which the motion state quantities to be estimated are the yaw rate and the lateral speed is shown, but any one of them or an apparatus for estimating another motion state quantity relating to yawing or lateral motion may be used.

The road surface information detected by the road surface state detecting means includes not only the road surface irregularities but also the road surface friction coefficient.

(Effects of the Invention) As described above, according to the present invention, in a vehicle state quantity estimating apparatus for estimating yaw or lateral motion vehicle motion information based on predetermined observation data, a yaw and lateral motion vehicle Since the feedback gain in estimating the motion information is set to an optimal value according to the road surface condition of the vehicle, the effect that accurate vehicle motion information can be estimated regardless of the road surface condition on which the vehicle travels. can get.

[Brief description of the drawings]

FIG. 1 is a claim correspondence diagram showing a vehicle state quantity estimating apparatus of the present invention, FIG. 2 is a view showing a vehicle to which the vehicle state quantity estimating apparatus of the embodiment is applied, and FIG. 3 is a vehicle state quantity estimating apparatus of the embodiment. FIG. 4 is a block diagram of the control for estimating the vehicle state quantity in the embodiment apparatus, FIG. 5 is a flowchart showing the flow of the state quantity estimation processing operation in the arithmetic processing unit, and FIG. It is each characteristic figure of the simulation result performed. a: front wheel steering angle detecting means b: vehicle speed detecting means c: vehicle plane motion information detecting means d: road surface state detecting means e: gain matrix f: estimation calculating section gain matrix determining section g: state quantity Estimation calculation unit

Claims (1)

(57) [Claims] 1. A front wheel steering angle detecting means for detecting a steering wheel angle or a front wheel actual steering angle of a steering wheel; a vehicle speed detecting means for detecting a vehicle speed; and a vehicle for detecting at least one component of motion information of a vehicle plane motion. Plane motion information detecting means, road surface state detecting means for detecting road surface information during traveling, a mathematical model of a vehicle plane motion identified in advance, a gain matrix set by the road surface state, and a value of the gain matrix for the road surface Estimation calculation unit gain matrix determination unit determined by the signal of the state detection unit, and signals of the front wheel steering angle detection unit, vehicle speed detection unit, and vehicle plane motion information detection unit are input, and the estimation calculation unit gain matrix determination unit By calculating the determined gain matrix and two or more integrators or an operation equivalent to integration, at least one of vehicle motion information of yawing and lateral motion is calculated. State quantity estimation calculation unit and the vehicle state quantity estimation apparatus which is characterized in that comprises a.