JPH034429B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention is applicable to ordinary two-wheel steering vehicles or four-wheel steering vehicles.
The present invention can be used as a steering device for a wheel-steering vehicle, and particularly relates to a vehicle steering control device that can freely control the motion performance of a vehicle during steering.

(Prior art) A conventional vehicle equipped with a mechanical link type steering device is configured to steer the front wheels in accordance with the amount of steering of the steering wheel, and the motion variables associated with steering are based on the vehicle's The driving performance is determined uniformly based on specifications, and is unique to each vehicle type.

(Problem to be solved by the invention) However, as mentioned above, in the case of conventional vehicles, in order to change the driving performance, it is necessary to change the vehicle specifications. It was difficult to provide good exercise performance.
This is because the vehicle specifications of a sports car are determined by the sports car's body structure and tire characteristics, resulting in a body structure that cannot be called a sedan car.

In addition, in the case of competition vehicles (rally cars), both acceleration performance and steering response are required to be excellent, but usually in order to improve acceleration performance, the engine displacement is increased. The vehicle weight increases, resulting in a decrease in steering responsiveness. Therefore, if an attempt is made to improve the steering response by reducing the vehicle body size and reducing the yaw inertia, it becomes impossible to mount a large engine, and acceleration performance cannot be improved.

In this way, in conventional vehicles, where the vehicle's dynamic performance is uniformly determined by the vehicle specifications,
It has various disadvantages.

(Means for Solving the Problems) In order to solve the above problems, the present invention, as conceptually shown in FIG _.
, a vehicle speed detection means 101 that detects the vehicle speed V, a target dynamic characteristic arbitrarily selected corresponding to the steering wheel steering input and the vehicle speed, and a dynamic characteristic of the own vehicle corresponding to the steering angle input of the front wheels or front and rear wheels and the vehicle speed. a calculation unit that calculates a target value of the wheel steering angle of either the front wheel or the rear wheel in order to realize the target dynamic characteristics in accordance with the detected steering wheel steering amount θ _s and the vehicle speed V; 200
and a wheel steering means 104 for steering either the front wheels or the rear wheels corresponding to the determined wheel steering angle target value.

(Operation) The calculation unit 200 calculates target dynamic characteristics arbitrarily selected corresponding to the steering wheel steering input (steering amount, steering speed, steering acceleration, etc.) and vehicle speed, and the steering angle input (steering angle amount) of the front wheels or front and rear wheels. , steering angle speed, steering angle acceleration, etc.) and the dynamic characteristics of the own vehicle corresponding to the vehicle speed, the means 100 and 101 detect a target steering angle value of the front wheels or rear wheels for realizing the target dynamic characteristics. It is determined in accordance with the steering wheel steering amount θ _s and the vehicle speed V. The wheel steering means 104 steers the corresponding front wheel or rear wheel so that the wheel steering angle target value obtained in this way is achieved.

Therefore, for example, even if the body structure of the own vehicle is of the sedan type, it is possible to give the vehicle the same dynamic performance as a sports vehicle depending on the selection of the target dynamic characteristics.

(Example) The configuration of one embodiment of the present invention is shown in FIG.

The microcomputer 1 inputs the vehicle speed V detected by the vehicle speed sensor 3 and the steering amount θ _s of the steering wheel 8 detected by the steering wheel steering amount sensor 2, and calculates the motion variable target value and rear wheel steering angle target. Performs an operation on the value _r .

The rear wheel steering device 5 is a device that performs steering control of the rear wheels 11 and 12 based on data of a rear wheel steering angle target value _r given from the microcomputer 1.

The hydraulic steering device 7 actually steers the rear wheels 11 and 12. This rear wheel steering device 5 and the hydraulic steering device 7
has a configuration as shown in FIG. 3, for example.

The hydraulic steering device 7 includes two pistons 32 and 33, with tie rods at both ends (not shown).
The shaft 31 connected to the left and right hydraulic chambers 3
The wheels are steered by moving them in the axial direction by setting a difference between the working oil pressures of the wheels 4 and 35.

Further, within the center chamber 37, repulsion plates 38 and 39, which are biased in left and right opposite directions by a spring 36, are loosely fitted onto the shaft 31. This is for returning the shaft 31 to its original neutral position when it is pulled out.

The rear wheel steering device 5 includes a solenoid driver 21
, control valve 22, and oil pump 2
6 and an oil tank 27.

The control valve 22 includes oil passages 28 and 29 that communicate with the left and right hydraulic chambers 34 and 35 of the hydraulic steering device 7, and includes a spool valve 25 that adjusts the amount of hydraulic oil flowing into these oil passages 28 and 29. ing. This spool valve 25 has its left and right ends loosely fitted into the electromagnetic solenoids 23 and 24.
It moves in the axial direction depending on the magnitude of the magnetic force of the electromagnetic solenoids 23 and 24, and adjusts the amount of hydraulic oil applied to the left and right hydraulic chambers 34 and 35.

The solenoid driver 21 sends a current signal proportional to the rear wheel steering angle target value _r given from the microcomputer 1 to either the left or right electromagnetic solenoid 2.
3,24. In this case, control is performed by switching the electromagnetic solenoid that applies current between the left and right sides depending on the steering direction of the wheels.

Further, the front wheels 9 and 10 are steered to a steering angle corresponding to the amount of steering of a steering wheel 8 by a mechanical link type steering device 6 similar to that of a conventional vehicle.

FIG. 4 is a flowchart showing the processing executed by the microcomputer 1. The operation of this embodiment will be explained below along with the explanation of this flowchart.

The process shown in FIG. 4 is repeatedly executed every predetermined time Δt, and when the ignition switch is
Initialization is performed when it is turned on and power is supplied.

In the process of step 41, the data of the steering wheel steering amount θ _s and the data of the vehicle speed V which are input from the steering wheel steering amount sensor 2 and the vehicle speed sensor 3 to the microcomputer 1 are read.

In the process of step 42, the target vehicle specifications stored in advance in the memory are read out. As the target vehicle specifications, vehicle specifications of a vehicle (this is referred to as a "target vehicle") different from the vehicle (own vehicle) in which the device of this embodiment is mounted are used. for example,
When the own vehicle is a sedan car, the vehicle specifications of the sports car are used as the target vehicle specifications. That is, the sports car is the target vehicle.

In this embodiment, the following vehicle specifications are used as target vehicle specifications.

I _Z1 : Yaw inertia of the target vehicle M ₁ : Vehicle weight of the target vehicle L ₁ : Wheelbase of the target vehicle L _F1 : Distance between the front axle and center of gravity of the target vehicle L _R1 : Distance between the rear axle and center of gravity of the target vehicle I _K1 : Target vehicle's inertia around the king pin K _S1 : Target vehicle's steering stiffness D _K1 : Target vehicle's steering system viscosity coefficient ξ ₁ : Target vehicle's trail N ₁ : Target vehicle's steering gear ratio K _F1 : Target vehicle's front wheels Cornering power K _R1 : Cornering power of the rear wheels of the target vehicle Then, in the next step 43, a calculation is performed to obtain the target motion variable (yaw angular acceleration in this example) using the target vehicle specifications. It will be done. This calculation is performed according to the following formula.

I _K1 δ¨ _f1 =N ₁ K _S1 (θ _s −N ₁ δ _f1 ) −D _K1 δ〓 _f1 −2ξ ₁ C _F1 ……(1) M ₁ (y¨ ₁ +〓 ₁ V) = 2C _F1 +2C _R1 …(2) I _Z1 ¨=2L _F1 C _F1 −2L _R1 C _R1 …(3) β _F1 = δ _f1 −(y〓 ₁ +L _F1 〓 ₁ )/V …(4) β _R1 =− (y〓 ₁ −L _R1 〓)/V ……(5) C _F1 ＝K _F1 β _F1 ……(6) C _R1 ＝K _R1 β _R1 ……(7) ¨＝¨ ₁ ……(8) Here where, δ _f1 : Front wheel steering angle of the target vehicle (assuming the target vehicle is a two-wheel steered vehicle) 〓 ₁ : Yaw rate of the target vehicle ¨: Yaw angular acceleration y of the target vehicle〓: Lateral speed y of the target vehicle _¨1 : Lateral acceleration of the target vehicle β _F1 : Side slip angle of the target vehicle's front wheels β _F1 : Side slip angle of the target vehicle's rear wheels C _F1 : Cornering force of the target vehicle's front wheels C _R1 : Side slip angle of the target vehicle's rear wheels Cornering Force ¨: Target value of yaw angular acceleration.

Equations (1) to (3) above are the equations of motion (target dynamic characteristics) for the target vehicle, and to solve these equations,
Four integral operations are required for each Δt, and this integral operation can be performed using, for example, the rectangular integral method expressed as A(t+Δt)=A(t)+Δt・A〓(t), other methods such as the Rungekutta method, etc. Use an appropriate integration method depending on the required integration accuracy.

In this way, the obtained yaw angular acceleration target value ¨ is the yaw angular acceleration of the target vehicle corresponding to the steering wheel steering amount θ _s and the vehicle speed V, and these motion variables of a vehicle different from the own vehicle are The aim of this embodiment is to achieve this.

Next, in the process of step 44, the vehicle specifications of the own vehicle stored in the memory in advance are read out. In this embodiment, the following vehicle specifications are used.

I _Z2 : Own vehicle _{'s yaw inertia M2: Own vehicle's vehicle weight L2: Own vehicle's wheelbase L F2 : Distance} between the own vehicle's front axle and center of gravity L _R2 : Distance between own vehicle's rear axle and center of gravity I _K2 : Inertia of the own vehicle around the kingpin K _S2 : Steering rigidity of the own vehicle D _K2 : Steering system viscosity coefficient of the own vehicle ξ ₂ : Trail N of the own vehicle ₂ : Steering gear ratio of the own vehicle K _F2 : Front wheel of the own vehicle Cornering power K _R2 : Cornering power of the rear wheels of the own vehicle Then, in the process of the next step 45, the vehicle specifications and dynamic characteristics of the own vehicle described above, and the cornering power of the own vehicle's rear wheels
A calculation is performed to determine the steering angle target value _r of the rear wheels of the own vehicle from the yaw angular acceleration target value r determined in .
This calculation is performed according to the following formula.

I _K2 δ¨ _f2 =N ₂ K _S2 (θ _S −N ₂ δ _f2 ) −D _K2 δ〓 _f −2ξ ₂ C _F2 ……(9) M ₂ (y¨ ₂ +〓 ₂ V) = 2C _F2 +2C _R …(10) β _F2 = δ _f2 − (y〓 ₂ +L _F2 〓 ₂ )/V …(11) C _F2 = K _F2 β _F2 …(12) C _R2 = (L _F2 C _F2 −1 /2¨I _Z2 )/L _R2 …(13) β _R2 =C _R2 /K _R2 …(14) _r = β _R2 +(y〓 ₂ −L _R2 〓 ₂ )/V …(15) However , 〓 ₂ = 〓 ₁ .

Here, δ _f2 : Front wheel steering angle of own vehicle ₂ : Yaw rate y of own vehicle ₂ : Lateral speed y of own vehicle ₂ : Lateral acceleration of own vehicle β _F2 : Side slip angle β of front wheels of own vehicle _R2 : Side slip angle of the rear wheels of the own vehicle C _F2 : Cornering force of the front wheels of the own vehicle C _R2 : Cornering force of the rear wheels of the own vehicle.

Equations (9) and (10) above are the equations of motion of the own vehicle, and the integral operation to solve these equations is performed in the steps above.
Use the integral method used in 43.

The rear wheel steering angle target value _r obtained by such calculation is input to the rear wheel steering device 5 through the process of the next step 46.

The rear wheel steering device 5 supplies the hydraulic pressure necessary for steering the rear wheels 11 and 12 to the given rear wheel steering angle target value δ _r to the hydraulic steering device 7. , 12 steerings are performed.

Through the above operations, the yaw angular acceleration of the own vehicle becomes the same value as that of the target vehicle, and as a result, the own vehicle has the same driving performance as the target vehicle. That is, for example, if the own vehicle is a sedan car and the target vehicle is a sports car, the vehicle body structure, etc. of the own car can be left as is, and the driving performance can be made to be that of a sports car.

Furthermore, it specifically shows how much change in exercise performance can actually be obtained.

Now, assume that the vehicle (self-vehicle) equipped with this embodiment device is a vehicle with a displacement of 2000 c.c. and a yaw inertia I _Z2 = 240 Kgf・m・s ² , and a target vehicle with the same displacement and a yaw inertia I _Z1 = 120Kgf・m・s ² Vehicle is set. It is assumed that other vehicle specifications are the same between the host vehicle and the target vehicle.

FIG. 5 is a diagram showing the change in yaw rate when the steering wheel is steered at 120 degrees in steps of 0.1 seconds when the vehicle speed is V=50 km/h with the above settings.

In addition, Fig. 6 shows the vehicle speed V = 100 with the above settings.
Km/h, the change in yaw rate gain/steering amount when applying ±30° steering wheel steering in a sinusoidal manner and changing the steering frequency from 0.1 to 2 Hz (this is called "frequency response") , is a diagram showing the phase thereof.

In addition, the characteristics shown by the solid line in FIGS. 5 and 6 above indicate the case where the above embodiment device is installed, and the characteristics shown by the broken line show the characteristics when the conventional mechanical link type steering device is installed. There is.

As shown in FIG. 5, when the device of this embodiment is installed, the steering response is significantly improved compared to the conventional system. That is, by the time the yaw rate reaches 90% of the steady state, the yaw rate, which used to be about 0.27 seconds, is reduced to about 0.17 seconds.

Furthermore, as shown in FIG. 6, when the device of this embodiment is installed, the frequency response performance is also improved compared to the conventional one. The effect of improving frequency response performance is particularly large when the frequency is high. At the same time, phase delay can also be reduced.

In addition, in the above embodiment, an example was shown in which a specific vehicle (for example, a sports car) is set as the target vehicle and control is performed using the vehicle specifications of the target vehicle. Instead of setting the target vehicle as the target vehicle, a virtual vehicle with ideal or required maneuverability may be used as the target vehicle.For example, in a rally car, it is equipped with a large engine and has a high steering response. It is also possible to improve sex.

Furthermore, it is also possible to set a midship vehicle as the target vehicle, and even a non-midship type vehicle can be given the same driving performance as a midship vehicle.

Furthermore, it is also possible to store a plurality of vehicle specifications of the target vehicle and to freely select the target vehicle according to the driver's preference.

In addition, in the above embodiment, an example was shown in which the yaw angular acceleration is obtained as the motion variable target value, but other motion variables such as cornering force, side slip angle, or centripetal G (centripetal acceleration) can be used as the target value. The number of target values is not limited to one, and two or more target values may be determined.

Furthermore, in the above embodiment, an example is shown in which the vehicle is applied to a four-wheel steering vehicle in which both the front wheels and the rear wheels can be steered, but this example is applied to a normal two-wheel steering vehicle in which only the front wheels can be steered. It is also possible. In this case, instead of a mechanically linked steering device between the steering wheel and the front wheels, e.g.
The hydraulic steering device as shown in the above embodiment may be used, and the front wheel steering angle target value may be calculated in step 45 in FIG.
In this way, the cost can be reduced by the amount of the rear wheel steering mechanism, and the structure can be simplified.

However, in an example in which the rear wheels are controlled as in the above embodiment, even if a failure occurs in the device, the front wheels can be steered as before, which is advantageous in terms of safety.

(Effects of the Invention) As explained in detail above, the present invention has the advantage that, while in conventional vehicles, the dynamic performance is determined by the vehicle specifications of the vehicle, The dynamic performance that is different from the determined dynamic performance can be freely changed without changing the vehicle body structure or the like.

As a result, for example, a regular vehicle can be given the same driving performance as a midship vehicle, or
It will also be possible to provide rally cars with high steering response even though they are equipped with large engines.

Further, when applied to a four-wheel steering vehicle, fewer additional parts are required, which is effective in terms of cost and workability.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of the present invention, Figure 2 is a block diagram showing the configuration of the present invention.
The figure is a block diagram of one embodiment of the present invention, FIG. 3 is a block diagram of the front wheel steering device, rear wheel steering device, and hydraulic steering device in FIG. 2, and FIG. 4 is a block diagram of the microcomputer in FIG. 2. 5 and 6 are characteristic diagrams specifically showing the steering responsiveness of a vehicle equipped with the device of the present invention. 100...Steering wheel steering amount detection means, 101...
...Vehicle speed detection means, 102...Motion variable target value calculation means, 103...Steering angle target value calculation means, 104...
... Wheel steering means, 200 ... Calculation unit, 1 ... Microcomputer, 2 ... Steering wheel steering amount sensor, 3 ... Vehicle speed sensor, 5 ... Rear wheel steering device, 7
... Hydraulic steering device, 8 ... Steering handle, 9, 10 ... Front wheels, 11, 12 ...
Rear wheel.

Claims (1)

[Scope of Claims] 1. Steering wheel steering amount detection means for detecting the steering amount of the steering wheel; vehicle speed detection means for detecting vehicle speed; target dynamic characteristics arbitrarily selected in accordance with the steering wheel steering input and the vehicle speed; It is configured using the steering angle input of the front wheels or front and rear wheels and the dynamic characteristics of the own vehicle corresponding to the vehicle speed, and the target value of the wheel steering angle of either the front wheel or the rear wheel is set as described above to realize the target dynamic characteristics. The vehicle comprises: a calculation unit that calculates a value corresponding to the detected steering wheel steering amount and vehicle speed; and a wheel steering unit that steers a wheel corresponding to either a front wheel or a rear wheel according to the determined wheel steering angle target value. A vehicle steering control device characterized by: 2. The calculation unit calculates a target value of a vehicle motion variable corresponding to the detected steering wheel steering amount and vehicle speed using a vehicle motion equation using vehicle specifications different from vehicle specifications of the own vehicle. a variable target value calculation means, and a motion equation using the determined motion variable target value and the vehicle specifications of the own vehicle to calculate either the front wheel or the rear wheel to realize the determined motion variable target value. 2. The vehicle steering control device according to claim 1, further comprising steering angle target value calculation means for determining a target value of the wheel steering angle.