JP5402024B2 - Steering control device and steering control method - Google Patents

Description

  The present invention relates to a steering control device and a steering control method.

  For example, in steering-by-wire, when the side slip angle of the vehicle increases in the spin direction, the front wheel steering angle is corrected in the direction to suppress the turning to automatically suppress the increase in the side slip angle and the reaction force in the direction to suppress the turning to the steering wheel. There has been a technique that prompts the driver to perform correction steering by applying torque (see Patent Document 1).

JP 2003-252229 A

Incidentally, in the conventional example described in Patent Document 1, the reaction force torque Trt is calculated according to the motor current of the steering actuator, and the correction torque Trc in the turning suppression direction is added to the reaction force torque Trt. Thus, the final reaction force torque is calculated. Therefore, if counter-steering is performed such that the front wheel rudder angle reverses beyond the neutral position, the direction of the reaction force torque Trt reverses and acts in a direction that cancels the correction torque Trc. On the other hand, it is not always possible to prompt corrective steering.
An object of the present invention is to prompt the driver to perform correction steering when correcting the turning angle of the steered wheels based on a predetermined condition different from the steering operation of the driver.

The steering control device according to the present invention detects a road surface reaction force acting on the steered wheels when controlling a steered angle of the steered wheels according to a steering operation of a driver, and detects a road surface reaction force corresponding to the road surface reaction force. One steering reaction force is transmitted to the driver, the turning angle is corrected based on a predetermined condition different from the driver's steering operation, and the turning direction is reversed when the turning angle is reversed beyond the neutral position. The second steering reaction force in the same direction is transmitted to the driver. When transmitting the second steering reaction force to the driver, the second steering reaction force is calculated by adding the additional reaction force to the first steering reaction force. The first steering reaction force is reduced and corrected, and the additional reaction force is increased.

  According to the steering control device of the present invention, when the turning angle of the steered wheels is corrected based on a predetermined condition different from the driver's steering operation, the second steering reaction force in the direction corresponding to the correction direction. Is transmitted to the driver, so that the driver can be prompted to perform corrective steering.

It is a schematic structure of a steering-by-wire. It is a block diagram of a controller. It is a specific example of an oversteer tendency. It is a flowchart which shows a turning behavior control process. It is a map used for calculation of correction amount (DELTA) (theta). It is a flowchart which shows a steering reaction force control process. It is a map used for calculation of steering reaction force Tr. It is a map used for calculation of additional reaction force Ta. It is a map used for correction | amendment of steering reaction force Tr. It is a time chart which shows the operation | movement of a turning behavior control process. It explains the reversal of the steering reaction force.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
"Constitution"
FIG. 1 is a schematic configuration diagram of a steering-by-wire.
The steering wheel 1 is connected to a steering shaft 2, and steered wheels (steering wheels) 3L and 3R are connected to a pinion shaft 7 through a knuckle arm 4, a tie rod 5, and a rack and pinion 6 in this order. The steering shaft 2 and the pinion shaft 7 are in a mechanically separated and unconnected state, and are respectively held rotatably by a housing or the like (not shown).
The steering shaft 2 is provided with a reaction force motor 8 that generates a pseudo steering reaction force in response to a steering operation by a driver. The pinion shaft 7 is provided with a pinion shaft 7 according to the steering angle of the steering shaft 2. A turning motor 9 is provided for turning.

  The steering shaft 2 is provided with a steering angle sensor 11 that detects the steering angle θs, and the pinion shaft 7 is provided with a turning angle sensor 12 that detects the turning angle θw. A hub sensor 13 for detecting a tire lateral force is provided in each of the left and right wheel hub units, and a vehicle speed sensor 14 for detecting a vehicle speed V is mounted on an output side of a transmission of a vehicle (not shown). The vehicle speed sensor 14 may detect the vehicle speed by detecting the rotational speed of the wheel. A yaw rate sensor 15 that detects an actual measurement value γs of the yaw rate is provided on the body that is on the spring. The steering angle sensor 11 and the turning angle sensor 12 detect a right turn as a positive value and a left turn as a negative value.

The hub sensor 13 uses, for example, a Hall element and a magnetized encoder to detect a change in the displacement difference between the inner ring and the outer ring in the hub unit, thereby generating a tire lateral force (road reaction force acting on the front wheels 1FL and 1FR). To detect. However, the present invention is not limited to this, and a strain gauge may be provided outside the bearing, and the tire lateral force may be detected by detecting deformation of the bearing.
Various signals detected by the steering angle sensor 11, the turning angle sensor 12, the hub sensor 13, the vehicle speed sensor 14, and the yaw rate sensor 15 are input to a controller 20 constituted by, for example, a microcomputer. The tire lateral force detected by the hub sensor 13 is inputted as a total value Yf.

As shown in FIG. 2, the controller 20 calculates a steered angle control unit 21 for driving and controlling the steered motor 9, a steering reaction force control unit 22 for driving and controlling the reaction force motor 8, and an estimated yaw rate value γe. An estimated value calculation unit 23 for turning, and a turning behavior control unit 24 for controlling the turning behavior of the vehicle.
The turning angle control unit 21 inputs the steering angle θs of the steering shaft 2 and the turning angle θw of the pinion shaft 7, and normally drives the turning motor 9 according to the steering angle θw to turn the turning angle. θw is controlled. On the other hand, when an after-mentioned correction amount Δθ is input from the turning behavior control unit 24, the turning angle θw is automatically corrected according to the correction amount Δθ.

The steering reaction force control unit 22 executes a steering reaction force control process to be described later, inputs the tire lateral force Yf and the vehicle speed V, and drives the reaction force motor 8 to control the steering reaction force Tr with respect to the steering operation.
The estimated value calculation unit 23 calculates an estimated value γe of the yaw rate according to the tire lateral force Yf and the vehicle speed V according to the following equation (1).
γe = {Yf × (L / Lr)} / (m × V) (1)
γe: Estimated value of yaw rate Yf: Tire lateral force of steered wheels L: Wheel base Lr: Distance between vehicle center of gravity and rear wheel axle m: Vehicle weight V: Vehicle speed However, vehicle speed V is lower than predetermined value V1 of low speed Sometimes, the predetermined value V1 is substituted into the above equation (1). This predetermined value V1 is a value of about 20 km / h, for example.

The above equation (1) will be described.
The vehicle motion equation of a general vehicle is expressed by the following equation (2).
may = Yf + Yr
Iγ = YfLf + YrLr (2)
ay: Lateral acceleration I: Yawing moment of inertia Yr: Rear wheel tire lateral force Lf: Distance between vehicle center of gravity and front wheel axle

At the time of steady turning (stable), it is expressed by the following equation (3).
may = Yf + Yr = mVγ
YfLf = YrLr (3)
If the above formula (3) is arranged, the following formula (4) is derived.
Yf {(Lf + Lr) / Lr} = mVγ (4)
Solving the equation (4) for γ (yaw rate) leads to the equation (1).

The turning behavior control unit 24 executes the turning behavior control process, and performs counter-steering when the vehicle detects an oversteer tendency, that is, corrects the turning angle θw in a direction to suppress the oversteer tendency. Stabilize the turning behavior. Further, when the turning angle θw is corrected, the steering reaction force Tr is corrected accordingly, thereby prompting the driver to make a correction steering that matches the correction of the turning angle θw.
FIG. 3 is a specific example of the oversteer tendency. For example, when the tire lateral force Yr of the rear wheel is saturated and the tire lateral force Yf of the front wheel increases due to the load movement due to the brake, the yaw rate increases and the oversteer tendency Become.

Next, the turning behavior control process will be described with reference to the flowchart of FIG.
In step S1, as shown below, a difference E1 between the actual measurement value γs and the estimated value γe is calculated.
E1 = γs−γe
In a succeeding step S2, it is determined whether or not the control flag is reset to F = 0. Note that the initial setting is reset to F = 0. Here, if the control flag is reset to F = 0, it is determined that the counter steer has not started yet, and the process proceeds to step S3. On the other hand, if the control flag is set to F = 1, it is determined that the counter steer is already started, and the process proceeds to step S6 described later.

  In step S3, it is determined whether or not the difference E1 is greater than a first predetermined value th1. The first predetermined value th1 is a relatively small value because it is a threshold value for determining the degree of deviation of the actual measurement value γs from the estimated value γe. If the determination result is E1 ≦ th1, it is determined that the vehicle does not have an oversteer tendency and the countersteer is unnecessary, and the process returns to the predetermined main program as it is. On the other hand, if the determination result is E1> th1, it is determined that the vehicle is on the verge of oversteering and there is a possibility that counter-steering is necessary, and the process proceeds to step S4.

In step S4, as shown below, the current estimated value γe is set as the target value γ ^* . That is, since the current estimated value γe is the limit of the turning performance just before the oversteer tendency, this estimated value γe is held as the yaw rate target value γ ^* .
γ ^* ← γe
In the subsequent step S5, the control flag is set to F = 1.
In the subsequent step S6, as shown below, a difference E2 between the actually measured value γs and the target value γ ^* is calculated.
E2 = γs−γ ^*

  In a succeeding step S7, it is determined whether or not the difference E2 is larger than a second predetermined value th2. Since the second predetermined value th2 is a threshold value for determining the deviation degree of the actual measurement value γs with respect to the target value γ *, it is a relatively small value and a value close to the first predetermined value th1 described above. If the determination result is E2> th2, it is determined that the vehicle is in an oversteer tendency and a countersteer is necessary, and the process proceeds to step S8. On the other hand, if the determination result is E2 ≦ th2, it is determined that there is no oversteer tendency at least at the present time and that countersteering is not necessary, and the process proceeds to step S10 described later.

In step S8, with reference to the map of FIG. 5, the correction amount Δθ of the turning angle θw is calculated according to the difference E2. This map is set so that the larger the difference E2, the larger the correction amount Δθ and the upper limit value. Note that any one of the characteristic lines L1, L2, and L3 may be arbitrarily selected until the upper limit is reached. The characteristic line L1 is a characteristic that increases the correction amount Δθ using only one proportional coefficient. The characteristic line L2 is a characteristic that increases the correction amount Δθ by using two different proportional coefficients depending on the magnitude of the difference E2. The characteristic line L3 is a characteristic in which the increase rate of the correction amount Δθ with respect to the addition rate of the difference increase E2 increases as the difference E increases. These characteristics may be characteristics selected in advance by experiments or the like in consideration of the characteristics of the vehicle and the uncomfortable feeling to the driver of the vehicle.
In the subsequent step S9, the correction amount Δθ is output to the turning angle control unit 21, and then the process returns to the predetermined main program.

On the other hand, in step S10, it is determined whether or not the difference E1 is smaller than the first predetermined value th1. If the determination result is E1 ≦ th1, it is determined that the oversteer tendency has been eliminated by the counter steer, and the process proceeds to step S11. On the other hand, if the determination result is E1> th1, it is determined that the oversteer tendency may be temporarily reduced, and the process proceeds to step S12.
In step S11, the control flag is reset to F = 0, and then the process returns to a predetermined main program.

  Step S12 determines whether or not the vehicle speed V is smaller than the third predetermined value th3, or whether or not the actual measurement value γs is smaller than the fourth predetermined value th4. The third predetermined value th3 is a threshold value for determining whether or not the vehicle speed V is in the low speed region, and is a value of about 15 km / h, for example. The fourth predetermined value th4 is a threshold value for determining whether or not the actual measurement value γs is sufficiently small, and is a value of, for example, about 10 deg / sec, which is smaller than the target value γ *. If the determination result is V <th3 or γs <th4, it is determined that the counter steer is no longer necessary, and the process proceeds to step S11. On the other hand, if the determination result is V ≧ th3 and γs ≧ th4, it is determined that the oversteer tendency may be temporarily reduced, and the process returns to the predetermined main program as it is.

Next, the steering reaction force control process will be described with reference to the flowchart of FIG.
In step S21, the steering reaction force Tr is calculated according to the tire lateral force Yf with reference to the map of FIG. This map is set so that the steering reaction force Tr increases in proportion to the tire lateral force Yf.
In a succeeding step S22, it is determined whether or not the turning angle θw is corrected by the turning behavior control process. If the turning angle θw is not corrected, the process proceeds to step S23. On the other hand, if the turning angle θw is corrected, the process proceeds to step S24.
In step S23, the steering reaction force Tr is output to the steering reaction force control unit 22, and then the process returns to a predetermined main program.

On the other hand, in step S24, referring to FIG. 8, the additional reaction force Ta is calculated according to the correction amount Δθ of the turning angle θw. This map is set so that the larger the correction amount Δθ and the faster the steering operation speed, the larger the additional reaction force Ta in the same direction as the correction amount Δθ and the upper limit value.
In subsequent step S25, referring to FIG. 9, the steering reaction force Tr is corrected to decrease in accordance with the additional reaction force Ta. This map is set so that the amount of decrease correction of the steering reaction force Tr increases as the additional reaction force Ta increases.
In the subsequent step S26, the additional reaction force Ta is added to the steering reaction force Tr to calculate the final steering reaction force Tr, and then the process proceeds to step S23.

<Action>
First, calculation of the estimated value γe will be described.
In general, it is known that the yaw rate is estimated based on the vehicle speed V and the steering angle θs. However, since the actual yaw rate is affected by the road surface friction coefficient, the yaw rate is calculated based on the vehicle speed V and the steering angle θs. The estimated value of the yaw rate needs to be corrected according to the friction coefficient. However, since it is difficult to accurately detect the friction coefficient, it is difficult to accurately estimate the yaw rate.

  Therefore, in the present embodiment, an estimated value γe of the yaw rate is calculated according to the tire lateral force Yf and the vehicle speed V according to the equation (1). Thus, by using the tire lateral force Yf, the yaw rate can be accurately estimated without being affected by the road surface friction coefficient. However, when the vehicle speed V is less than or equal to the low predetermined value V1, the predetermined value V1 is substituted into the equation (1) to calculate the estimated value γe. That is, according to the above equation (1), the estimated value γe increases as the vehicle speed V decreases. Therefore, by providing a lower limit value for the vehicle speed V to be substituted, the estimation value γe is prevented from being maximized, and in accordance with the actual situation. An estimated value γe can be calculated.

Next, the control of the turning behavior will be described according to the time chart of FIG.
When the difference E1 is calculated (step S1) and the difference E1 is smaller than the first predetermined value th1 (determination in step S3 is “No”), that is, when the actual measurement value γs approximates the estimated value γe, Since the vehicle is not in an oversteer tendency and no countersteer is required, the control of the turning behavior is turned off as shown by the section T1 of the time chart.

When the actually measured value γs increases from this state and the difference E1 exceeds the first predetermined value th1 (determination in step S3 is “Yes”), the estimated value γe at that time is set as the target value γ ^* (step S4). ). Since the present estimated value γe is the limit of the turning performance just before the tendency toward oversteer, this estimated value γe is held as the target value γ ^* .
Then, the difference E2 is calculated (step S6), and when the difference E2 is larger than the second predetermined value th2 (determination in step S7 is “Yes”), the correction amount Δθ of the turning angle θw according to the difference E2 Is calculated (step S8), and counter steering is performed according to the correction amount Δθ, so that the control of the turning behavior is turned on as shown by the section T2 of the time chart.

As described above, the yaw rate as a limit of turning performance of the verge of reaching the oversteer, and set as a target value gamma ^*, according to the difference E2 between the target value gamma ^* and the measured value gamma] s, performs counter-steering Thereby, stabilization of turning behavior can be prevented while preventing deterioration of turning performance. That is, when the actual measurement value γs approaches the target value γ ^* , the correction amount Δθ is reduced, and when the actual measurement value γs is far from the target value γ ^* , the correction amount Δθ is increased, so You can steer.

Thereafter, when the actual measurement value γs approximates the target value γ ^* and the difference E2 becomes smaller than the second predetermined value th2 (determination in step S7 is “No”), the calculation of the correction amount Δθ is stopped and the counter steer is stopped. The vehicle is temporarily stopped and the turning behavior control is set to standby as indicated by a time chart section T3. This is because the estimated value γe is not stable at this time, and the actually measured value γs may increase again. In general, the stronger the first oversteer tendency (first wave), the oversteer tendency (second wave) may appear again due to inertia, even if the oversteer tendency once weakens by a single counter-steer operation. is there. Therefore, if the difference E2 is smaller than the second predetermined value th2, the control of the turning behavior is not immediately ended, and the vehicle is on standby for a case where an oversteer tendency appears again. In this way, by temporarily stopping the control of the turning behavior while maintaining the setting of the target value γ ^* , when the oversteer tendency appears again, the turning behavior is immediately controlled based on the same target value γ ^* . Control can be resumed.

In the standby state, the actually measured value γs may temporarily become smaller than the target value γ ^* , but the counter steer in the increasing direction is not performed, and the standby state is maintained as it is.
Then, when an oversteer tendency appears again and the difference E2 becomes larger than the second predetermined value th2 (determination in step S7 is “Yes”), the countersteer is restarted according to the correction amount Δθ, so that the time chart As indicated by the section T4, the turning behavior control is once again turned ON.

Thereafter, when the difference E2 becomes smaller than the second predetermined value th2 again and the difference E1 becomes smaller than the first predetermined value th1 (determination in Step S10 is “Yes”), the calculation of the correction amount Δθ and the counter steer are performed. The control of the turning behavior is turned off as shown in the section T5 of the time chart. At this time, the setting of the target value γ ^* is canceled by resetting the control flag to F = 0 (step S11). Therefore, thereafter, when the difference E1 becomes larger than the first predetermined value th1, the target value γ ^* is set again.

  On the other hand, if the difference E1 is larger than the predetermined value th1, the difference E2 is smaller than the second predetermined value th2 and the vehicle speed V is smaller than the third predetermined value th3 (determination in step S11 is “Yes”). The calculation of the amount Δθ and the counter steer are finished, and the control of the turning behavior is finished. This is because the turning behavior does not become a big problem when the vehicle is traveling at a low speed.

  Further, even if the difference E1 is larger than the predetermined value th1, if the difference E2 is smaller than the second predetermined value th2 and the measured value γs is smaller than the fourth predetermined value th4 (determination in step S11 is “Yes”). The calculation of the correction amount Δθ and the counter steer are finished, and the control of the turning behavior is finished. This is also because the turning behavior does not become a big problem when the vehicle has a low yaw rate, as in the case of traveling at a low speed.

Next, the steering reaction force Tr will be described.
Normally, the steering reaction force Tr corresponding to the driver's steering operation is calculated according to the map of FIG. 7 (step S21). On the other hand, when the vehicle oversteer tendency is detected and the steering angle θw is automatically corrected by countersteering, a steering reaction force Tr is generated so as to urge the driver to perform correction steering in accordance with the automatic correction.
By the way, when countersteering is performed such that the turning angle θw is reversed beyond the neutral position, the direction of the steering reaction force Tr according to the tire lateral force Yf is reversed, and as shown in FIG. It will act in the direction of blocking.

  Therefore, in the present embodiment, when the turning angle θw is automatically corrected (the determination in step S22 is “Yes”), a steering reaction force Tr in the same direction as this correction is generated. Specifically, the additional reaction force Ta is calculated according to the correction amount Δθ (step S24), and the steering reaction force Tr is corrected to decrease according to the additional reaction force Ta (step S25). By adding the additional reaction force Ta (step S26), a final steering reaction force Tr is generated.

  Here, first, as the correction amount Δθ is larger, the steering reaction force Tr is corrected to be reduced, so that even if the turning angle θw is reversed beyond the neutral position, the force in the direction that prevents the correction steering can be suppressed. . Further, by adding the additional reaction force Ta in the same direction as the correction amount Δθ, it is possible to cancel the force in the direction that hinders the correction steering and to prompt the driver to perform the correction steering in accordance with the automatic correction of the turning angle θw. . Further, by increasing the additional reaction force Ta as the correction amount Δθ increases, the driver can be urged to perform correction steering in accordance with the automatic correction of the turning angle θw. On the other hand, the quicker the steering operation by the driver, the smaller the additional reaction force Ta can be prevented, so that the correction steering is not overcut. Further, by limiting the additional reaction force Ta to a predetermined upper limit value or less, an unnecessary increase in the additional reaction force Ta can be prevented, and delicate correction steering can be easily performed.

《Application example》
In the present embodiment, the tire lateral force Yf is detected using a Hall element and a magnetized encoder. However, this type of hub sensor 13 can accurately detect the tire lateral force when the vehicle speed is extremely low. There is a possibility that Yf cannot be detected. Therefore, when the vehicle speed V is equal to or lower than the low speed predetermined value V1, the drive current of the steered motor 9 is detected, the rack axial force is detected, the pinion torque is detected, and these are used instead. The estimated value γe may be calculated. Thereby, even if the vehicle speed V is low, the estimation of the yaw rate can be continued.

  In this embodiment, the yaw rate estimated value γe is calculated according to the tire lateral force Yf and the vehicle speed V, but the present invention is not limited to this. That is, according to the equation (1), the vehicle weight m is also a variable element. Therefore, instead of setting the vehicle weight m as a fixed value, the vehicle weight m is detected based on the suspension stroke detected by the stroke sensor or the pitching state of the vehicle detected by the acceleration sensor, and this is also substituted into the above (1). The estimated value γe may be calculated. Similarly, since the distance Lr between the vehicle center of gravity and the rear axle is also a variable element, the vehicle center of gravity is detected based on the suspension stroke detected by the stroke sensor and the vehicle pitching state detected by the acceleration sensor. The estimated distance γe may be calculated by calculating the distance Lr from the wheel axle and also substituting it into (1). Thus, more accurate estimation can be performed by detecting the vehicle weight m and the vehicle gravity center point and reflecting them in the calculation of the estimated value γe.

In the present embodiment, the estimated value γe of the yaw rate is calculated according to the equation (1), but the present invention is not limited to this. For example, a first-order lag low-pass filter may be added to the process of calculating the estimated value γe, and the estimated value γe of the yaw rate may be calculated according to the following equation (5).
γe = {{Yf × (L / Lr)} / (m × V)}
× (1/1 + Ts) ………… (5)

  The hub sensor 13 is attached to a hub unit that is unsprung, while the yaw rate sensor 15 is attached to a vehicle body that is sprung. Therefore, strictly speaking, a phase delay occurs in the actual yaw rate value γs detected by the yaw rate sensor 15 with respect to the estimated yaw rate value γe calculated according to the tire lateral force Yf. That is, this phase shift affects the determination of the turning behavior. Therefore, according to the equation (4), the phase of the estimated value γe coincides with the phase of the actually measured value γs by adding a first-order lag low-pass filter to the estimated value γe calculation process. Thereby, the phase shift between the estimated value γe and the actually measured value γs can be eliminated, and the determination accuracy of the turning behavior can be improved.

  Further, in the present embodiment, the control of the turning behavior is finished when the difference E2 is smaller than the second predetermined value th2 and the difference E1 is smaller than the first predetermined value th1. It is not limited. For example, the control of the turning behavior may be terminated when a predetermined time elapses in a state where the difference E2 is smaller than the second predetermined value th2 and the difference E1 is smaller than the first predetermined value th1. According to this, ON / OFF of control can be switched more carefully.

  In this embodiment, the control of the turning behavior is terminated when the difference E2 is smaller than the second predetermined value th2 and the difference E1 is smaller than the first predetermined value th1, but the present invention is limited to this. It is not a thing. For example, the standby mode may be omitted, and the turning behavior control may be immediately terminated when the difference E2 becomes smaller than the second predetermined value th2. According to this, ON / OFF of control can be switched more simply.

In the present embodiment, the steering reaction force Tr corresponding to the tire lateral force Yf is corrected to decrease, and the additional reaction force Ta is added to calculate the final steering reaction force Tr. It is not limited to. In short, when the turning angle θw is corrected based on a predetermined condition different from the driver's steering operation, it is sufficient that the steering reaction force in the same direction as this correction can be transmitted to the driver. The corresponding steering reaction force Tr may be ignored, and the steering reaction force in the same direction as the correction of the turning angle θw may be newly calculated.
Further, in the present embodiment, the steering-by-wire has been described. However, the present invention is not limited to this. If the steering angle θw is corrected based on a predetermined condition different from the driver's steering operation, the steering The present invention is also applicable to a system that controls the turning angle θw of the steered wheels by a variable angle ratio mechanism (VGR).

  In the present embodiment, the case where the steering angle θw is corrected by countersteering when an oversteer tendency of the vehicle is detected is described, but the present invention is not limited to this. For example, if braking force is generated on split μ roads with different road surface friction coefficients between the left and right wheels, the vehicle will unilaterally flow to the side where the road surface friction coefficient is higher, so the steering angle θw is automatically corrected in the reverse direction of the unidirectional flow. The present invention can also be applied to such a case or when the turning angle θw is automatically corrected in the departure prevention direction when a deviation tendency of the host vehicle from the traveling lane is detected. In short, the present invention can be applied to any other configuration as long as the turning angle θw is corrected under conditions different from the driver's steering operation.

"effect"
From the above, the turning angle control unit 21 corresponds to the “steering angle control unit”, the turning behavior control unit 24 corresponds to the “steering angle correction unit”, and the processing of steps S21 and S23 is “first reaction force”. Corresponding to “control means”, the processing of steps S22 to S26 corresponds to “second reaction force control means”.
(1) Steering angle control means capable of controlling the turning angle of the steered wheels according to the driver's steering operation, and turning angle correction for correcting the turning angle under predetermined conditions different from the driver's steering operation. And a road surface reaction force acting on the steered wheel when the steering angle control unit controls the turning angle according to a steering operation of a driver, and a first response according to the road surface reaction force is detected. When the first reaction force control means for transmitting the steering reaction force to the driver and the turning angle correction means correct the turning angle based on a predetermined condition different from the steering operation of the driver, Second reaction force control means for transmitting a second steering reaction force in a direction corresponding to the direction of correction of the turning angle to the driver.
As described above, when the turning angle of the steered wheels is corrected based on a predetermined condition different from the driver's steering operation, the second steering reaction force in the same direction as this correction is transmitted to the driver. Corrective steering can be urged to the person.

(2) The turning angle correction means corrects the turning angle in order to suppress an oversteer tendency of the vehicle.
Thereby, the oversteer tendency of vehicles can be controlled.
(3) The second reaction force control means increases the second steering reaction force as the amount of correction of the turning angle increases.
As a result, the driver can be prompted to perform corrective steering in accordance with the correction of the turning angle.
(4) The second reaction force control means calculates the second steering reaction force by adding an additional reaction force to the first steering reaction force, and corrects the turning angle. As the amount increases, the first steering reaction force is corrected to decrease and the additional reaction force is increased.
As a result, even if the turning angle is reversed beyond the neutral position, the force in the direction of preventing the correction steering can be suppressed, so that the driver can be prompted to perform the correction steering in accordance with the correction of the turning angle.

(5) The second reaction force control means decreases the additional reaction force as the driver's steering operation becomes faster.
Thereby, it is possible to prevent excessive correction steering.
(6) The second reaction force control means limits the additional reaction force to a predetermined upper limit value or less.
As a result, an unnecessary increase in the additional reaction force can be prevented, and delicate correction steering can be easily performed.

(7) When controlling the turning angle of the steered wheels according to the steering operation of the driver, the road surface reaction force acting on the steered wheels is detected, and the first steering reaction force according to the road surface reaction force is detected. When the turning angle is corrected based on a predetermined condition that is transmitted to the driver and different from the steering operation of the driver, the second steering reaction force in the same direction as the correction is transmitted to the driver.
As described above, when the turning angle of the steered wheels is corrected based on a predetermined condition different from the driver's steering operation, the second steering reaction force in the same direction as this correction is transmitted to the driver. Corrective steering can be urged to the person.

3L, 3R steered wheel 8 reaction force motor 9 steered motor 11 steering angle sensor 12 steered angle sensor 13 hub sensor 14 vehicle speed sensor 15 yaw rate sensor 20 controller 21 steered angle control unit 22 steering reaction force control unit 23 estimated value calculation unit 24 Steering control unit

Claims (7)

Steering angle control means capable of controlling the turning angle of the steered wheels in accordance with the steering operation of the driver, turning angle correction means for correcting the turning angle under a predetermined condition different from the steering operation of the driver,
When the steering angle control means controls the turning angle according to a driver's steering operation, a road reaction force acting on the steered wheel is detected, and a first steering reaction force according to the road reaction force is detected. First reaction force control means for transmitting to the driver,
The turning angle correction means corrects the turning angle based on a predetermined condition different from the steering operation of the driver, and the turning angle is corrected when the turning angle is reversed beyond the neutral position. A second reaction force control means for transmitting a second steering reaction force in the same direction as the direction to the driver ,
The second reaction force control means calculates the second steering reaction force by adding an additional reaction force to the first steering reaction force, and the correction amount of the turning angle is large. The steering control device is characterized by decreasing the first steering reaction force and increasing the additional reaction force .   The steering control device according to claim 1, wherein the turning angle correction unit corrects the turning angle in order to suppress an oversteer tendency of the vehicle.   3. The steering control device according to claim 1, wherein the second reaction force control unit increases the second steering reaction force as the amount of correction of the turning angle increases.   The second reaction force control means calculates the second steering reaction force by adding an additional reaction force to the first steering reaction force, and the correction amount of the turning angle is large. The steering control device according to claim 3, wherein the first reaction force is decreased and corrected, and the additional reaction force is increased.   5. The steering control device according to claim 4, wherein the second reaction force control unit reduces the additional reaction force as the driver performs a steering operation faster.   The steering control device according to any one of claims 3 to 5, wherein the second reaction force control means limits the additional reaction force to a predetermined upper limit value or less. When controlling the turning angle of the steered wheels according to the driver's steering operation, the road surface reaction force acting on the steered wheels is detected, and the first steering reaction force according to the road surface reaction force is given to the driver. When the turning angle is corrected based on a predetermined condition different from the steering operation of the driver and the turning angle is reversed beyond the neutral position , the second steering in the same direction as the correction direction is performed. The reaction force is transmitted to the driver ,
When the second steering reaction force is transmitted to the driver, the second steering reaction force is calculated by adding an additional reaction force to the first steering reaction force, and the turning angle is corrected. A steering control method characterized by reducing the first steering reaction force and increasing the additional reaction force as the amount increases .

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