JP2003048565A - Vehicular steering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a practical vehicular steering system that gives no sense of discomfort to a driver by improving the stability of vehicle behavior. SOLUTION: A movement of a steering actuator 2 is transmitted to wheels so as to generate a steering angle change. An operational process for controlling the steering actuator 2 uses parameters correlated with the inertial mass and center-of-gravity position of a vehicle. A plurality of values of the parameters are predetermined and stored according to differences in at least either of the size and location of a variable inertial mass as a part of the inertial mass of the vehicle. A mode signal is generated according to a difference in at least either of the size and location of the variable inertial mass. The operational process reads out and uses values of the parameters stored according to at least either of the size and location of the variable inertial mass corresponding to the mode signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering system that changes a steering angle by controlling a steering actuator.

[0002]

2. Description of the Related Art In a vehicle steering system that transmits the movement of a steering actuator to wheels so as to change the steering angle, when a calculation for controlling the steering actuator is performed, the vehicle when the steering angle changes In order to accurately perform the dynamic compensation in the control for stabilizing the behavior, a parameter correlated with the inertial mass and the position of the center of gravity of the vehicle is used in the calculation process. The parameters include, for example, the inertial mass of the vehicle, the yaw moment of inertia, the front wheel cornering power, the rear wheel cornering power, the center of gravity-front axle distance, the center of gravity-rear axle distance, and a vehicle characteristic parameter indicating vehicle characteristics such as a stability factor. Also, control parameters such as gain and time constant are used.

Conventionally, as the vehicle characteristic parameters and control parameters, fixed values obtained by experiments conducted in advance under constant conditions have been used.

[0004]

In the conventional control, the vehicle behavior changes due to changes in the number of occupants of the vehicle, seating positions of the occupants, fuel amount, etc., which hinders the stabilization of the vehicle behavior and makes the driver feel uncomfortable. There is a problem of giving. It is an object of the present invention to provide a vehicle steering system that can solve the problem.

[0005]

SUMMARY OF THE INVENTION The present invention is directed to a steering actuator, a means for transmitting the movement of the steering actuator to a wheel so as to cause a change in the steering angle, and a calculation for controlling the steering actuator. In a vehicle steering system that uses a parameter that correlates to the inertial mass of the vehicle and the position of the center of gravity of the vehicle in the process of calculation, at least one of the size and the arrangement of the variable inertial mass that forms a part of the inertial mass of the vehicle. Means for storing a plurality of values of the parameter predetermined according to one difference and means for generating a mode signal according to at least one of the magnitude and arrangement of the variable inertial mass are provided. ,
In the calculation process, the value of the parameter stored according to at least one of the size and the arrangement of the variable inertial mass corresponding to the mode signal is read out and used. According to the configuration of the present invention, in the calculation process for controlling the steering actuator, the magnitude of at least one variable inertial mass that forms a part of the inertial mass of the vehicle is used as a parameter that correlates with the inertial mass of the vehicle and the position of the center of gravity. And the value according to the arrangement is used. As a result, it is possible to suppress changes in vehicle behavior due to changes in the size and arrangement of the variable inertial mass.

The magnitude of the variable inertial mass is set to a preset value, and a mode changeover switch is provided which can be changed over according to the difference in the number and arrangement of the variable inertial mass, and the mode changeover switch is changed over. It is preferable that the mode signal is output in response to an operation. This allows
It is not necessary to detect the magnitude of the variable inertial mass, the occupant can output the mode signal only by switching the mode changeover switch, and the control system can be simplified.

It is preferable that a variable inertial mass detection sensor for detecting the size and arrangement of the variable inertial mass is provided, and the mode signal is output according to the detection result of the sensor. Thus, the magnitude of the variable inertial mass can be accurately obtained, and the mode signal can be automatically output to reduce the burden on the occupant.

The variable inertial mass is preferably at least one of the vehicle occupant, fuel and cargo. This makes it possible to deal with a change in the variable inertial mass that greatly affects the change in the inertial mass of the vehicle.

As the parameters, the inertial mass of the vehicle,
It is preferable to use yaw moment of inertia, front wheel cornering power, rear wheel cornering power, center of gravity-front axle distance, center of gravity-rear axle distance, and stability factor. As a result, it is possible to accurately cope with the change in the inertial mass of the vehicle.

Based on the mode signal, the values of some of the parameters used in the calculation process are read out,
It is preferable to include means for calculating the values of the remaining parameters used in the calculation process based on the values of the parameters read based on the mode signal. With this, when a plurality of values of the parameter are predetermined according to a difference in at least one of the size and the position of the variable inertial mass, it is possible to reduce the number of types of the parameters for which the plurality of values are predetermined. It is possible to reduce the work effort when configuring

Based on the mode signal, it is preferable that the values of all parameters used in the calculation process can be read. As a result, it is possible to accurately cope with a change in the inertial mass of the vehicle.

A vehicle steering system according to the present invention comprises an operating member,
A means for obtaining a target behavior index value according to the operation amount of the operation member and a means for obtaining a behavior index value serving as an index of vehicle behavior caused by a change in the steering angle are provided, and the obtained behavior index value and target behavior index value It is preferable that the calculation for controlling the steering actuator is performed according to Accordingly, when the vehicle behavior is changed according to the operation of the operation member, it is possible to reduce the variation of the vehicle behavior due to the variation of the inertial mass of the vehicle and prevent the driver from feeling uncomfortable.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A vehicle steering system shown in FIG. 1 includes an operating member 1 imitating a steering wheel, a steering actuator 2 driven by a rotating operation of the operating member 1, and a steering actuator 2. A steering gear 3 for transmitting the movement to the front left and right wheels 4 so as to change the steering angle without mechanically connecting the operation member 1 to the wheels 4.

The steering actuator 2 can be constituted by an electric motor such as a known brushless motor. The steering gear 3 is composed of a motion conversion mechanism such as a ball screw mechanism that converts the rotational motion of the output shaft of the steering actuator 2 into the linear motion of the steering rod 7. The movement of the steering rod 7 is transmitted to the wheel 4 via the tie rod 8 and the knuckle arm 9, and the toe angle of the wheel 4 changes. The steering gear 3 may be a known one,
The structure is not limited as long as the movement of the steering actuator 2 can be transmitted to the front left and right wheels 4 so that the steering angle changes. The wheel alignment is set so that the front left and right wheels 4 can be returned to the straight-ahead position by the self-aligning torque when the steering actuator 2 is not driven.

The operating member 1 is connected to a rotary shaft 10 which is rotatably supported by the vehicle body. The output shaft of the operating actuator 19 is integrated with the rotary shaft 10. The operating actuator 19 can be configured by an electric motor such as a brushless motor.

An elastic member 30 is provided which gives an elastic force in the direction of returning the operating member 1 to the straight steering position. The elastic member 30 can be composed of, for example, a spring that gives elasticity to the rotary shaft 10. When the operating actuator 19 does not apply torque to the rotary shaft 10, the elastic force of the operating member 1 returns the operating member 1 to the straight-ahead steering position.

An angle sensor 11 for detecting the rotation angle δh of the operation member 1 from the straight-ahead position is provided as the operation amount of the operation member 1. The rotation angle δh is used as an input value. A rudder angle sensor 1 as means for detecting the rudder angle δ of the vehicle
3 is provided, and in the present embodiment, it is configured by a potentiometer that detects the operation amount of the steering rod 7 corresponding to the steering angle δ. A speed sensor 14 that detects the vehicle speed V of the vehicle and a lateral acceleration sensor 15 that detects the lateral acceleration Gy of the vehicle are provided. A yaw rate sensor 1 for detecting a yaw rate γ of the vehicle as a behavior index value corresponding to a vehicle behavior generated as a result of the change in the steering angle δ.
6 is provided. The operating torque Th of the operating member 1
A torque sensor 12 for detecting The angle sensor 11, the torque sensor 12, the steering angle sensor 13, the speed sensor 14, the lateral acceleration sensor 15, and the yaw rate sensor 16 are connected to a control device 20 including a computer. The control device 20 controls the steering actuator 2 and the operation actuator 19 via the drive circuits 22 and 23 so that the vehicle behavior when the steering angle changes can be stabilized.

FIG. 2 is a block diagram for explaining the function of the control device 20. K1 is a gain of the target operation torque Th ^{* with} respect to the rotation angle δh of the operation member 1, and is a predetermined relationship between Th ^* = K1 · δh and the angle sensor 1.
The target operation torque Th ^* is calculated from the rotation angle δh detected by 1. The gain K1 is adjusted so that optimum control can be performed.

G1 is a transfer function of the target drive current ih ^* of the operating actuator 19 with respect to the deviation between the target operating torque Th ^* and the operating torque Th. The control device 20 determines the target drive current ih ^* from the relationship of ih ^* = G1 · (Th ^* -Th) stored in advance, the calculated target operation torque Th ^*, and the operation torque Th detected by the torque sensor 12. Calculate For example, when performing PI control, the transfer function G1 has a gain K2, a Laplace operator s, and a time constant τa, and G1 = K2 [1 + 1 / (τa ·
s)]. The gain K2 and the time constant τa are adjusted so that optimum control can be performed. Its target drive current i
The operation actuator 19 is driven according to h ^* .

Kγ is a gain of the target yaw rate γ ^* with respect to the rotation angle δh of the operating member 1, and the control device 20 has a relationship of γ ^* = Kγ · δh stored in advance and the rotation detected by the angle sensor 11. A target yaw rate γ ^* is calculated from the angle δh. That is, the target behavior index value corresponding to the input rotation angle δh is obtained. The gain Kγ is adjusted so that optimum control can be performed.

G2 is a target yaw rate γ ^* and a yaw rate γ of the vehicle 100 detected by the yaw rate sensor 16.
Yaw rate compensation value γa ^* for deviation (γ ^* -γ) from
Is a transfer function of and constitutes a feedback compensation element in the control system. The controller 20 calculates the yaw rate compensation value γa ^* from the relationship of γa ^* = G2 · (γ ^* −γ) stored in advance and the calculated target yaw rate γ ^* and the yaw rate γ detected by the yaw rate sensor 16. To do. The transfer function G2 is obtained, for example, by the following equation (1). G2 = Kp + Ki / s + Kd · s (1) Here, Kp, Ki, and Kd are gains and are appropriately set so that optimum control can be performed.

G3 is a transfer function of the target steering angle δ ^{* with} respect to the sum (γ ^* + γa ^* ) of the target yaw rate γ ^* and the yaw rate compensation value γa ^*, and constitutes a feedforward compensation element in the control system. The controller 20 calculates the target steering angle δ ^* from the relationship of δ ^* = G3 · (γ ^* + γa ^* ) stored in advance and the calculated target yaw rate γ ^* and the yaw rate compensation value γa ^* . The transfer function G3 is obtained, for example, by the following equation (2). G3 = Kc · Ke · (Tc · s + 1) / (Tv · s + 1) (2) Here, among the control parameters Kc, Ke, Tc, and Tv, the gain Ke is appropriately set so that optimum control can be performed, The remaining control parameters Kc, Tc, Tv are obtained by the following equations (3), (4), (5). here,
Let ζ be the damping coefficient in the change of the vehicle behavior with respect to the change of the steering angle, ωn be the natural angular frequency, M be the inertial mass of the vehicle, Lf be the center of gravity-front axle distance, V be the vehicle speed, and Lr be the center of gravity-rear axle distance. Is the wheel base of L = Lf + Lr, and Kr is the rear cornering power. Kc = 1 / Kv (3) Tc = 2ζ / ωn (4) Tv = M · Lf · V / (2L · Kr) (5) The Kv is obtained by the following equation (6). Where A
Is the stability factor. Kv = V / {L (1 + A · V ² )} (6) ζ is obtained from the following equation (7). Here, J is the yaw moment of inertia of the vehicle and Kf is the front wheel cornering power. ζ = {M (Lf ² Kf + Lr ² Kr) + J (Kf + Kr)} / P (7) The ωn is calculated by the following equation (8). ω n = P / (V · M · J) (8) The stability factor A is obtained by the following equation (9). A = −M (Lf · Kf−Lr · Kr) / (2L ² · Kf · Kr) (9) The P is calculated by the following equation (10). P = 2L {M ・ L ・ Kf ・ Kr) (1 + A ・ V ² )} ^1/2 (10)

G4 is a transfer function of the target drive current Im ^* of the steering actuator 2 with respect to the target steering angle δ ^* .
The target drive current Im ^* to the target steering angle [delta] ^*, the control unit 20, Im ^* = G4 · ^{δ *} and the relationship is calculated from the target steering angle [delta] ^* and computed. The transfer function G4 is, for example, P
When I control is performed, G4 = K4 [1 + 1 / (τd · s)], where K4 is a gain and τd is a time constant, and the gain K4 and the time constant τd are adjusted so that optimum control can be performed. As a result, the steering actuator 2 is controlled by the control device 20 so that the steering angle δ corresponds to the target steering angle δ ^* .

As described above, in the present embodiment, the inertial mass M and the center of gravity of the vehicle are calculated in the process in which the controller 20 performs the calculation for controlling the steering actuator 2 according to the yaw rate γ and the target yaw rate γ ^*. As the parameters correlated with the position, the inertial mass M of the vehicle, the yaw moment of inertia J, the front wheel cornering power Kf, the rear wheel cornering power Kr, the center of gravity-front axle distance Lf, the center of gravity-
The vehicle characteristic parameters of the rear axle distance Lr and the stability factor A are used, and Kv, ωn, P, Tv,
The control parameter of ζ is used.

In the present embodiment, among the above parameters, a plurality of values of the inertial mass M of the vehicle, the distance Lf between the center of gravity and the front axle, and the distance Lr between the center of gravity and the rear axle are the inertial mass M of the vehicle.
Of the variable inertial mass that forms a part of the variable inertial mass and the arrangement of the variable inertial mass, and is stored in the controller 20. In this embodiment, the variable inertial mass is the inertial mass of the vehicle occupant and the load. The following Table 1 shows the inertial mass M of the vehicle, the center of gravity-front axle distance Lf, and the center of gravity-rear axle distance L according to the difference between the number of passengers and the load and the arrangement of the vehicle.
An example of the measured value of r is shown. The vehicle has two front left and right seats, three rear left-center-right seats, and a rear cargo loading trunk. In the present embodiment, the inertial mass of the occupant and the inertial mass of the load, which are the magnitudes of the variable inertial masses, are set to preset values. In addition, the numbers and arrangements of the occupants and the loads in Table 1 are examples, and the present invention is not limited to these. Further, the variable inertial mass is not limited to the inertial masses of the occupant and the cargo, and at least one of the size and the arrangement may be a part of the variable vehicle inertial mass, and may be the inertial mass of fuel, for example.

[0026]

[Table 1]

Means are provided for generating a mode signal in response to a difference in at least one of the magnitude and the arrangement of the variable inertial mass. As the mode signal generating means, a mode changeover switch 21 connected to the control device 20 is provided in this embodiment. The mode changeover switch 21 is switchable according to the difference in the number and arrangement of the variable inertial mass, and can be constituted by, for example, a key switch having a key corresponding to the number and arrangement of the occupant and the load. The driver operates the mode selector switch 21 at the start of driving the vehicle. The mode signal is output according to the switching operation of the mode selector switch 21. The control device 20 uses the steering actuator 2
In the calculation process for controlling, the value of the parameter stored according to the magnitude and arrangement of the variable inertial mass corresponding to the mode signal, that is, the inertial mass M of the vehicle, the center of gravity −
The values of the front axle distance Lf and the center of gravity-rear axle distance Lr are read out and used. A variable inertial mass detection sensor for detecting the size and arrangement of the variable inertial mass may be provided and the mode signal may be output according to the detection result of the sensor. For example, a load cell is provided at each seat position or trunk of the vehicle to detect the occupant and the inertial mass and arrangement of the load. Thereby, the magnitude of the variable inertial mass can be accurately obtained, and the mode signal can be automatically output to reduce the burden on the occupant.

In the present embodiment, the values of some of the parameters used in the above calculation process are read out based on the mode signal, and based on the values of the parameters read out based on the mode signal, that is, the inertial mass of the vehicle. Based on the values of M, the center of gravity-front axle distance Lf, and the center of gravity-rear axle distance Lr, the values of the remaining parameters used in the above calculation process, that is, the yaw inertia moment J, the front wheel cornering power Kf, and the rear wheel cornering power Kr. , Stability factor A, control parameters Kv, ωn, P,
The values of Tv and ζ are calculated by the control device 20 as follows. It should be noted that, in accordance with the difference in at least one of the size and the arrangement of the variable inertial mass, a plurality of values for each of all parameters used in the above calculation process are predetermined and stored, and based on the mode signal, in the above calculation process, The values of all the parameters used may be readable. As a result, it is possible to accurately cope with a change in the inertial mass M of the vehicle.

Vehicle inertial mass M, center of gravity-front axle distance L
f, the remaining parameters from the center of gravity-rear axle distance Lr
When determining the vehicle speed,
Steady values for ear angle δ, lateral acceleration Gy, and yaw rate γ are required
And About vehicle speed V, steering angle δ, yaw rate γ
Indicates that the sensor output is not strictly constant even in the steady state.
Therefore, in this embodiment, it can be regarded as a steady state.
Average the detection data in the range, and the average value of each
V_AV, Δ_AV, Γ_AVIs adopted as a steady value, and
Yaw moment of inertia J_AV, Front wheel cornering
Power Kf_AV, Rear wheel cornering power Kr_AV, Studio
Ability factor A_AVFor steering actuator 2
The calculation for the control of is performed. Below is the average value of the parameters
Is a sign_AVIs attached to the detection data_DTAttach. side
For acceleration Gy, the sensor output depends on the body roll.
Since the gravity acceleration component is included, the correction coefficient obtained below
Cg_AVAnd roll coefficient φ_AVValue Gy corrected using_AVSet
Used as a normal value. Φ is the roll angle of the vehicle body and gravitational acceleration
Let g be the lateral acceleration detected by the lateral acceleration sensor 15.
Acceleration Gy_DTIs the actual lateral acceleration as shown in the following equation (11).
Apparently larger than Gy. Gy_DT= GycosΦ + gsinΦ (11) Therefore, Gy_DTWas calculated by the following formula (12)
The sideslip angular velocity β ′ does not become zero even in the steady state. β ′ = Gy_DT/ V-γ (12) In the actual steady state (β ′ = 0), lateral acceleration and yaw
The relationship of G is expressed by the following equation (13). Gy_AV= Γ_AV・ V_AV                                            (13) From the equation (13), the correction coefficient Cg of the lateral acceleration sensor output is
It is given by the following equation (14). Cg = Gy_AV/ Gy_DT= Γ_AV・ V_AV/ Gy_DT                      (14) Cg is calculated from equation (14) within the steady state range of each data.
Therefore, the average value Cg of all data _AVIs adopted as the roll coefficient
It On the other hand, the mounting position of the lateral acceleration sensor 15 is
Assuming that it is at the center point, Φ≈sinφ, cosΦ≈1
In the range (Φ <2-4 deg) that can be considered as
The following relational expression (15) is obtained from (11). Gy / Gy_DT= 1-Φ (g / Gy_DT) (15) From equations (14) and (15), the average value φ of the roll angle_AVIs next
Equation (16) is obtained. φ_AV= (Gy_DT-Γ_AV・ V_AV) / G (16) In addition, the roll rigidity of the vehicle is Kφ, and the roll axis and the center of gravity are
If the distance is h,
Equation (17) is obtained. Kφ ・ Φ = h ・ M ・ GycosΦ + h ・ M ・ g ・ sinΦ (17) The following expression (18) is obtained from the expressions (11) and (17). φ = (h ・ M / Kφ) Gy_DT                                    (18) Therefore, the apparent roll coefficient Cφ for lateral acceleration is
The following expression (19) is obtained. Cφ = h ・ M / Kφ = Φ_AV/ Gy_DT                              (19) Cφ is calculated from equation (19) within the range of steady state of each data.
Therefore, the average value Cφ of all data _AVTo adopt. This allows
The average value of lateral acceleration is calculated from the following equation (20). Gy_AV= Cg_AV・ (1-g ・ Cφ_AV) ・ Gy_DT                    (20)

Average value K of cornering powers Kf and Kr
f _AV and Kr _AV can be identified as follows. The relational expression between the lateral acceleration Gy of the vehicle and the tire side slip angular velocities βf and βr in the turning state is the following equation (21). M · Gy = 2 (Kf · βf + Kr · βr) (21) Considering that in the steady state, the lateral forces of the front and rear wheels do not interfere with each other and act on the respective shared loads Wf, Wr, Kf _AV , Kr _AV Is given by the following equations (22) and (23). Kf _AV = Wf · Gy _AV / 2βf _AV (22) Kr _AV = Wr · Gy _AV / 2βr _AV (23) In addition, the average value of the integral value data of β ′ obtained in the steady state range by the formula (2) is calculated. As β _AV , βf _AV is βf _AV =
determined by _{δ-β AV -Lf · γ AV} / V AV, βr AV
Is determined by βr _AV = −β _AV + Lr · γ _AV / V _AV . Expressions (29) and (3) described later are added to the expressions (22) and (23).
Substituting the relationship of 0), the following relational expression (24) derived from the balance of yaw moments (constant yaw rate)
It turns out that it is equivalent to. Kr _AV / Kf _AV = (Lf / Lr) · (βf _AV / βr _AV ) (24) Here, βf _AV and βr _AV are represented by the following equations (25) and (26). βf _AV = δ−β _AV −Lf · γ _AV / V _AV (25) βr _AV = −β _AV + Lr · γ _AV / V _AV (26) In the steady state of each data (the front wheel steering angle and the sideslip angle are constant) In the range, Kf _AV and Kr _AV are calculated from equations (22) and (23).
Ask for. At this time, Kr _AV / Kf _AV is also obtained. Since the values of Kf _AV and Kr _AV of each data are easily affected by the variation of βf _AV and βr _AV , the average value (Kf _AV ) of all data is further added.
_AV , (Kr _AV ) _AV is preferably used. Kr _AV / Kf
_AV likewise preferred to use an average value of all data (Kr _AV / Kf _AV). Note that Kr _AV / Kf _AV may be obtained from equation (24). That is, in the steady state range of each data, (Lf / Lr) · (βf _AV / β in Equation (24)
r _AV ) and finally the average value (Lf · βf _AV
/Lr.βr _AV ) _AV is used. In addition, each data (β
r _AV , βf _AV ), and the slope of the regression line βf _AV /
It is also possible to obtain βr _AV and then obtain Kr _AV / Kf _AV from equation (24).

The stability factor A _AV can be identified using the yaw rate steady-state gain Kv. That is, in the steady state, the steady gain K of the yaw rate γ with respect to the steering angle δ
v is the following expression (27). Kv = V / {L (1 + A · V ² )} (27) From this, A _AV is expressed by the following equation (28). A _AV = 1 / (L · V _AV · Kv _AV ) −1 / V _AV ² (28) A _AV is calculated for each vehicle speed, and the average value (A _AV ) _AV of all data is used. The stability factor A _AV may be identified using the cornering powers Kf _AV and Kr _AV . That is, A _AV is calculated by the following equation from the stability factor definition equation, and A _AV = −M (Lf · Kf _AV −Lr · Kr _AV ) /
(2L ² · Kf _AV · Kr _AV ) The average value (A _AV ) _AV of all data obtained may be used.

The yaw moment of inertia J _AV can be identified based on the yaw motion of the vehicle in a transient state. That is, the relationship between the yaw rate change speed dγ / dt and the tire sideslip angles βf and βr in the turning state is expressed by the following equation (29). J · dγ / dt = 2 (Lf · Kf · βf−Lr · Kr · βr) (29) Then, J is approximated by the following equation (30). J = 2 (Lf * Kf * [beta] f-Lr * Kr * [beta] r) [Delta] t / [Delta] [gamma] (30) where [Delta] t is the control period (e.g., 8.192 ms), [Delta] t.
γ is the yaw rate deviation in one control cycle. In the transient state until the vehicle reaches the steady turning state, J is calculated by the equation (31) for each control cycle, the average value J _AV in the transient state is calculated, and the average value (J _AV ) _{AV of} all data is obtained. To use.

Referring to the flowchart of FIG. 3, the control device
A control procedure of the steering actuator 2 by 20 will be described.
It First, the parameters stored according to the mode signal
Read the values of M, Lf, and Lr (step 1), then
Detection by each sensor 11, 12, 13, 14, 15, 16
The output value is read (step 2). Next, respond to the mode signal.
Based on the values of the parameters M, Lf, and Lr stored
Parameters J, Kf, Kr, A, Kv, ωn, P,
The values of Tv and ζ are calculated as described above, and the value obtained immediately before is calculated.
Update (step 3). Next, the detection rotation of the operation member 1
Target operation torque Th from angle δh^* Th^*= K1 · δ
From the relationship of h (step 4), the calculated T
h^* And the detected operating torque Th
Target drive current ih of Eta 19^* Ih^* = G1 ・ (T
h^* -Th) relationship (step 5)
Target drive current ih^* Depending on the
To drive. Also, the target yaw rate according to the detected rotation angle δh
Gamma^* Is calculated based on the gain Kγ (step
6). The desired target yaw rate γ^* And detected yaw rate
Deviation from γ (γ^* −γ) corresponding to the yaw rate compensation value γ
a^* Is γa^* = G2 · (γ^* −γ)
(Step 7), the calculated target yaw rate γ^* And yo
-Rate compensation value γa ^* Sum of (γ^* + Γa^* )
Target steering angle δ^* And δ^* = G3 · (γ^* + Γa^* ) Seki
The calculation is performed by the operator (step 8). In this calculation process
Read out according to the mode signal in step 1.
And the values of the parameters M, Lf, and Lr in step 3
Parameters J, Kf, Kr, A, Kv, ω calculated by
The values of n, P, Tv and ζ are used. In addition, step 3
Parameters J, Kf, Kr, A, K calculated in
The values of v, ω n, P, Tv, and ζ are
The steady state of the vehicle and the transient state leading to that steady state
And their values are obtained from
Up to a predetermined initial setting value stored in the control device 20
Is used. Next, the calculated target steering angle δ^* Corresponds to
Target drive current Im ^* Im^* = G4 ・ δ^* From the relationship
The target driving current Im is calculated (step 9).^* According to
The steering angle δ is
Target rudder angle δ^*For steering actuator 2
To control. Then, determine whether to end the control (step
Step 10) If not completed, return to Step 1. So
For example, the key switch for starting the vehicle is turned on.
Whether or not it can be determined.

According to the above-described embodiment, in the calculation process for controlling the steering actuator 2, the variable inertial mass forming a part of the inertial mass M of the vehicle is used as a parameter correlated with the inertial mass M of the vehicle and the position of the center of gravity. Values of the inertial mass M, the center of gravity-front axle distance Lf, and the center of gravity-rear axle distance Lr are used according to the size and arrangement of the inertial mass of the occupant and the load. As a result, it is possible to suppress changes in vehicle behavior due to changes in the size and arrangement of the inertial mass of the occupant and the load. Further, it is not necessary to detect the magnitudes of the occupant and the inertial mass of the load, and the occupant can output the mode signal only by switching the mode changeover switch 21, and the control system can be simplified. Since the variable inertial mass is the occupant and the load of the vehicle, it is possible to cope with the change in the variable inertial mass that greatly affects the variation in the inertial mass M of the vehicle. Further, as its parameters, the inertial mass M of the vehicle, the yaw moment of inertia J, the front wheel cornering power Kf, the rear wheel cornering power Kr, the center of gravity-front axle distance Lf, the center of gravity-
By using the distance Lr between the rear axles and the stability factor A, it is possible to accurately respond to the change in the inertial mass M of the vehicle. By calculating the values of the remaining parameters based on the values of some of the parameters M, Lf, and Lr read out based on the mode signal, values can be set in advance in accordance with the difference in the inertial mass of the occupant and the load and the difference in arrangement. Since only some of the parameters M, Lf, and Lr need to be obtained, it is possible to reduce work effort when configuring the control system. Then, when the vehicle behavior is changed according to the operation of the operation member 1, the variation of the vehicle behavior due to the variation of the inertial mass of the vehicle can be reduced, and the driver can be prevented from feeling uncomfortable.

The present invention is not limited to the above embodiment. For example, the present invention can be applied to a steering device in which an operating member and wheels are mechanically connected. Further, the input value is not limited to the operation amount of the operation member, and for example, the operation torque Th obtained by the torque sensor 12 may be obtained and the target yaw rate γ ^* corresponding to the operation torque Th may be obtained. Furthermore, in a vehicle equipped with an automatic steering device that allows the vehicle to travel along a target track, the steering system that determines the deviation between the target track and the actual track as an input value and the target behavior index value according to the deviation is also used. The invention can be applied. The behavior index value of the vehicle is not limited to the yaw rate. For example, the lateral acceleration may be the behavior index value, or both the yaw rate and the lateral acceleration may be the behavior index values.

[0036]

According to the present invention, it is possible to provide a practical vehicle steering system in which the stability of the vehicle behavior is improved and the driver does not feel uncomfortable.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a vehicle steering system according to an embodiment of the present invention.

FIG. 2 is a control block diagram of the vehicle steering system according to the embodiment of the present invention.

FIG. 3 is a flowchart showing a control procedure of the vehicle steering system according to the embodiment of the present invention.

[Explanation of symbols]

1 Operation member 2 Steering actuator 3 steering gear Four wheels 11 Angle sensor 13 Rudder angle sensor 14 Speed sensor 15 Lateral acceleration sensor 16 Yaw rate sensor 20 Control device 21 Mode selector switch

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B62D 119: 00 B62D 119: 00 131: 00 131: 00 137: 00 137: 00 F term (reference) 3D032 CC02 DA03 DA15 DA23 DA29 DA33 DA64 DD01 DD02 DD05 DD06 DD07 EB02 EB16 EB17 EC23 3D033 CA03 CA13 CA14 CA16 CA17 CA20 CA28 CA29 CA31

Claims (8)

[Claims] 1. A steering actuator, means for transmitting a movement of the steering actuator to a wheel so as to change a steering angle, and means for performing a calculation for controlling the steering actuator. In the process, in a vehicle steering system that uses a parameter that correlates with the inertial mass and the position of the center of gravity of the vehicle, a predetermined value is determined according to a difference in at least one of the size and the arrangement of the variable inertial mass that forms a part of the inertial mass of the vehicle. Means for storing a plurality of values of the parameter, and means for generating a mode signal in accordance with a difference in at least one of the magnitude and the arrangement of the variable inertial mass are provided, and the mode in the calculation process is provided. The value of the parameter stored according to at least one of the magnitude and the arrangement of the variable inertial mass corresponding to the signal is read and used. Vehicle steering apparatus according to claim Rukoto. 2. The size of the variable inertial mass is set to a preset value, and a mode changeover switch is provided which can be changed over according to the difference in the number and arrangement of the variable inertial mass, and the mode changeover switch. The vehicle steering system according to claim 1, wherein the mode signal is output in response to the switching operation of. 3. The vehicle steering system according to claim 1, further comprising a variable inertial mass detection sensor for detecting the size and arrangement of the variable inertial mass, and outputting the mode signal according to the detection result of the sensor. . 4. The variable inertial mass is an inertial mass of at least one of a vehicle occupant, fuel and cargo.
The vehicle steering system according to any one of 1. 5. The inertial mass of the vehicle as the parameter,
The yaw moment of inertia, front wheel cornering power, rear wheel cornering power, center of gravity-front axle distance, center of gravity-rear axle distance, stability factor are used.
The vehicle steering system according to any one of 4 above. 6. The values of some parameters used in the calculation process are read out based on the mode signal,
The vehicle steering system according to any one of claims 1 to 5, further comprising means for calculating a value of a remaining parameter used in the calculation process based on a value of the parameter read based on the mode signal. 7. The vehicle steering system according to claim 1, wherein the values of all parameters used in the calculation process can be read out based on the mode signal. 8. An operation member, means for obtaining a target behavior index value according to an operation amount of the operation member, and means for obtaining a behavior index value serving as an index of vehicle behavior caused by a change in the steering angle, and the determination thereof. The vehicle steering system according to claim 1, wherein a calculation for controlling the steering actuator is performed according to the behavior index value and the target behavior index value.