JPH034428B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention can be applied to a steering device for a four-wheel steering vehicle capable of steering front and rear wheels. The present invention relates to a vehicle steering control device that can freely control the vehicle.

(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 determined by the amount of motion of the vehicle. Dynamic performance is determined uniformly based on vehicle 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 in order to improve acceleration performance, it is usually necessary to increase the engine displacement by increasing the vehicle body. The 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.

As described above, conventional vehicles in which the driving performance of the vehicle is uniformly determined by the vehicle specifications have 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 and rear wheels and the vehicle speed. a calculation unit 200 which calculates a front wheel steering angle target value _f and a rear wheel steering angle target value _r for realizing the target dynamic characteristics in accordance with the detected steering wheel steering amount θ _s and vehicle speed V, respectively; , front wheel steering means 104 for steering the front wheels to the determined front wheel steering angle target value _f ; and rear wheel steering means 105 for steering the rear wheels to the determined rear wheel steering angle target value _r . It has been set up and configured.

(Operation) The calculation unit 200 calculates target dynamic characteristics arbitrarily selected corresponding to steering wheel steering inputs (steering amount, steering speed, steering acceleration, etc.) and vehicle speed, and steering angle inputs for front and rear wheels (front and rear wheel steering inputs). A front wheel steering angle target value _f and a rear wheel steering angle target are used to achieve the above target dynamic characteristics by using the dynamic characteristics of the own vehicle corresponding to the vehicle speed, etc.) and the vehicle speed. value _r
are determined corresponding to the steering wheel steering amount θ _s and the vehicle speed V detected by means 100 and 101, respectively. The front wheel steering means 104 and the rear wheel steering means 105 respectively steer the corresponding front wheels and rear wheels so that the front wheel steering angle target value _f obtained in this manner becomes _r .

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. Furthermore, since the control inputs are both front wheel steering angle control and rear wheel steering angle control, a plurality of control outputs (yaw rate and lateral acceleration) can be easily matched to 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 the front wheel steering angle target value. Calculates _f and rear wheel steering angle target value _r .

The front wheel steering device 4 is a device that performs steering control of the front wheels 9 and 10 based on data of the front wheel steering angle target value _f given from the microcomputer 1.
Similarly, the rear wheel steering device 5 is a device that performs steering control of the rear wheels 11 and 12 based on data of the rear wheel steering angle target value _r given from the microcomputer 1.

The hydraulic steering devices 6 and 7 actually steer the front wheels 9, 10 and the rear wheels 11, 12.
It is.

The front wheel steering device 4, the rear wheel steering device 5, and the hydraulic steering devices 6, 7 are configured as shown in FIG. 3, for example.

The hydraulic steering devices 6 and 7 are equipped with two pistons 32 and 33, and drive a shaft 31 whose both ends are connected to tie rods (not shown) by providing a difference in the working oil pressure between left and right hydraulic chambers 34 and 35. The wheels are steered by moving them in the axial direction.

In addition, in the center chamber 37, repulsion plates 38 and 39 biased in left and right opposite directions by a spring 36 are loosely fitted to the shaft 31, and this is caused by the hydraulic pressure of the left and right hydraulic chambers 34 and 35. This is for returning the shaft 31 to its original neutral position when the shaft 31 is pulled out.

The front and rear wheel steering devices 4 and 5 are composed of a solenoid driver 21, a control valve 22, an oil pump 26, 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 devices 6 and 7.
Spool valve 2 that adjusts the amount of hydraulic oil flowing into the
It is equipped with 5. This spool valve 25 is
The left and right ends are loosely fitted into the electromagnetic solenoids 23 and 24, and move in the axial direction depending on the magnitude of the magnetic force of the electromagnetic solenoids 23 and 24, and the left and right hydraulic chambers 34 and 3
Adjust the amount of hydraulic oil given to 5.

The solenoid driver 21 receives front and rear wheel steering angle target values _f given from the microcomputer 1,
A current signal proportional to δ _r is supplied to either the left or right electromagnetic solenoids 23 and 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.

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 (hereinafter referred to as a "target vehicle") different from the vehicle (own vehicle) in which the device of this embodiment is installed 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 and both 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, the target motion variables (in this example, yaw angular acceleration and lateral G (lateral A computation is performed to obtain the acceleration)). 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) _G =y¨ ₁ +〓 ₁ V...(9) Here, δ _f1 : Front wheel steering angle of the target vehicle (assuming that the target vehicle is a two-wheel steering vehicle) 〓 ₁ : Yaw rate of the target vehicle ¨ ₁ : Target Yaw angular acceleration of the vehicle y〓 ₁ : Lateral speed of the target vehicle y¨ ₁ : Lateral translational acceleration of the target vehicle β _F1 : Side slip angle of the front wheels of the target vehicle β _F1 : Side slip angle of the rear wheels of the target vehicle C _F1 : Cornering force of the front wheels of the target vehicle C _R1 : Cornering force of the rear wheels of the target vehicle ¨: Yaw angular acceleration target value _G : Lateral G target value.

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 ¨ and lateral G target value _G are the yaw angular acceleration and lateral G of the target vehicle corresponding to the steering wheel steering amount θ _s and the vehicle speed V. The aim of this embodiment is to make the own vehicle realize the motion variables of different vehicles.

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 : Yaw inertia _of own vehicle _M2 : Vehicle weight L2: Wheelbase of own vehicle L _F2 : Distance between front axle and center of gravity of own vehicle L _R2 : Distance between rear axle and center of gravity of own vehicle K _F2 : Cornering power of the front wheels of the own vehicle 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
From the yaw angular acceleration target value ¨ and the lateral G target value _G found in
An operation is performed to obtain _f and _r . This calculation is performed according to the following formula.

C _F2 = 1/2L ₂ (M ₂ L _{R2 G} +I _Z2 ¨ ...(10) C _R2 = 1/2L ₂ (M ₂ L _{F2 G} −I _Z2 ¨ ...(11) β _F2 = C _F2 /K _F2 ……(12) β _R2 =C _R2 ／K _R2 ……(13) _f =β _F2 +(y〓 ₂ +L _F2 〓 ₂ )/V ……(14) _r =β _R2 +(y〓 ₂ +L _R2 〓 ₂ )/V ... (15) However, y 〓 ₂ = y 〓 ₁ and 〓 ₂ = 〓 ₁ .

Here, C _F2 : Cornering force of the front wheels of the own vehicle C _R2 : Cornering force of the rear wheels of the own vehicle β _F2 : Side slip angle of the front wheels of the own vehicle β _R2 : Side slip angle of the rear wheels of the own vehicle〓 ₂ : Own vehicle's yaw rate y〓 ₂ : This is the own vehicle's lateral speed.

The front and rear wheel steering angle target values _f and _f obtained by such calculations are input to the front wheel steering device 4 or the rear wheel steering device 5, respectively, through the process of the next step 46. .

The front wheel steering device 4 and the rear wheel steering device 5 supply hydraulic pressure necessary for steering the front wheels 9, 10 or the rear wheels 11, 12 to a given steering angle target value _f or _r to a hydraulic steering device 6. ,7,
As a result, the front wheels 9, 10 and the rear wheels 11, 12
The steering is carried out.

Through the above operations, the yaw angular acceleration of the own vehicle and the lateral G of the own vehicle become the same values as those 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 driving performance can be made to be that of a sports car while the body structure of the own car remains the same.

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 has a displacement of 2000 c.c. and a yaw inertia I _Z2 = 240 Kgf・m・s ² , and as a target vehicle, a vehicle with the same displacement and a yaw inertia of Set a vehicle with I _Z1 = 120Kgf・m・S ² . It is assumed that other vehicle specifications are the same between the host vehicle and the target vehicle.

Figure 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, and Figure 6 is similar. It is a figure which shows the change of the lateral G in the state.

In addition, Figures 7 and 8 show the yaw rate when the vehicle speed V = 100 km/h with the above settings, the steering wheel is steered by ±30 degrees in a sine wave pattern, and the steering frequency is varied from 0.1 to 2 Hz. FIG. 4 is a diagram showing changes in gain/steering amount and lateral G gain/steering amount (these are referred to as "frequency response") and their phases.

In addition, the characteristics shown by the solid lines in FIGS. 5 to 8 above show the characteristics when the above embodiment device is mounted on the tower, and the characteristics shown by the broken line show the characteristics when the conventional mechanical link type steering device is mounted on the tower. It shows.

As shown in FIGS. 5 and 6, when the device of this embodiment is mounted on a tower, the steering response is significantly improved compared to the conventional one. For example, by the time the yaw rate reaches 90% of steady state, it has traditionally been around
What used to be 0.27s is now about 0.17s.

Furthermore, as shown in FIGS. 7 and 8, when the device of this embodiment is mounted on a tower, 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, a large engine is installed and the steering It is also possible to improve responsiveness.

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 and lateral G were obtained as the motion variable target values.
Motion variables other than these, such as cornering force and sideslip angle, may be determined as target values, and instead of two target values, one target value may be used, or three or more target values may be used. .

(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. Furthermore, since the control inputs are both front wheel steering angle control and rear wheel steering angle control, a plurality of control outputs (yaw rate and lateral acceleration) can also be easily made to match the target dynamic characteristics.

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 a rally car with a large engine and high steering response.

[Brief explanation of drawings]

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 to 8 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...
...Front wheel steering means, 105...Rear wheel steering means, 20
0... Arithmetic unit, 1... Microcomputer, 2
...Handle steering amount sensor, 3...Vehicle speed sensor,
4...Front wheel steering device, 5...Rear wheel steering device, 6,
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; The detected steering wheel steering amount is configured using the dynamic characteristics of the own vehicle corresponding to the steering angle input of the front and rear wheels and the vehicle speed, and determines the target values of the front wheel steering angle and the rear wheel steering angle to realize the target dynamic characteristics. and a calculation unit that calculates the value corresponding to the vehicle speed; a front wheel steering means that steers the front wheels to the determined front wheel steering angle target value; and a rear wheel steering unit that steers the rear wheels to the determined rear wheel steering angle target value. What is claimed is: 1. A vehicle steering control device comprising wheel steering means. 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 target value of a front wheel steering angle and a rear wheel steering angle for realizing the determined motion variable target value, based on the determined motion variable target value and the vehicle specifications of the host vehicle. 2. The vehicle steering control device according to claim 1, further comprising a steering angle target value calculation means for calculating the steering angle target value.