JP2019206268A - Steering control device - Google Patents

Abstract

To provide a steering control device that can achieve an appropriate steering feeling even on a ramp.SOLUTION: When a vehicle travels on a first ramp, a curved road with transverse slope, a correction processing part 85 of a control device increases a target pinion angle θwhich is used to calculate ideal axial force by a correction quantity θ. When the vehicle travels on a second ramp, a straight road with transverse slope, the correction processing part 85 decreases the target pinion angle θwhich is used to calculate the ideal axial force by the correction quantity θ. The correction processing part 85 calculates the correction quantity θcorresponding to a gravity component Gby using a first map M1 and a second map M2 that specify a relation between the gravity component Gand the correction quantity θin a direction along the transverse slope of the road.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a steering control device.

  2. Description of the Related Art Conventionally, there is known an electric power steering device that assists a driver's steering operation by applying power of an electric motor to a vehicle steering mechanism. For example, an EPS controller in Patent Document 1 controls an electric motor based on a steering torque, a steering angle, and a wheel steering angle acquired through various sensors.

  The controller has first and second reference models (models in which control objectives are formulated). The first normative model defines the relationship between the steering angle and the target steering torque, and the second normative model defines the relationship between the steering torque and the target turning angle. The controller performs PID (proportional, integral, differential) control, which is a kind of feedback control, based on the target steering torque and the target turning angle determined by the first and second reference models.

  The controller obtains the deviation of the actual steering torque with respect to the target steering torque determined by the first reference model and the deviation of the actual steering angle with respect to the target turning angle determined by the second reference model, respectively. The electric motor is controlled so as to eliminate the deviation. Through the control, the controller causes the actual steering torque to follow the target steering torque and the actual turning angle to follow the target turning angle.

Japanese Patent No. 4453012

  Here, when a vehicle that does not have the second reference model travels on a bank road that is a curved road having a cross slope, for example, the steering wheel is caused by a balance of forces (gravity and centrifugal force) acting on the vehicle. Even if the steering torque is not applied by the driver, the steering angle position (tire position) according to the inclination of the bank road is obtained. That is, the driver does not need to perform a large turning operation of the steering wheel while traveling on the bank road.

  However, in the vehicle having the second reference model, since the actual steering angle corresponding to the steering torque is realized, if the steering torque is not applied while traveling on the bank road, the steering may be returned to the neutral position. Concerned. For this reason, the driver needs to apply a steering torque so that the steering does not return to the neutral position while traveling on the bank road.

  The same problem occurs when the vehicle travels on a cant road that is a straight road having a crossing gradient. That is, during traveling on a cant road, if the driver does not continue to hold the steering wheel by applying force to the steering wheel, the vehicle cannot keep running along the route on the cant road, and gradually, as the vehicle advances, Drive in the form of descending towards the lower side. This is because the vehicle is affected by the inclination of the road surface.

  In this way, whether the vehicle is traveling on a bank road or a cant road, the driver is required to apply a force corresponding to the inclination of the road surface to the steering wheel in order to drive the vehicle along the route. It is necessary to continue to steer. For this reason, the driver may not be able to obtain an appropriate steering feeling while traveling on a bank road or a cant road.

  An object of the present invention is to provide a steering control device capable of obtaining an appropriate steering feeling even on an inclined road.

  A steering control device that can achieve the above object controls a motor, which is a source of driving force applied to a steering mechanism of a vehicle, based on a command value calculated according to a steering state. The steering control device includes a first calculation unit, a second calculation unit, a third calculation unit, a fourth calculation unit, and a fifth calculation unit. The first calculation unit calculates a first component of the command value according to a steering torque applied to the steering wheel. The second calculation unit calculates a target rotation angle of the rotating body that rotates in conjunction with the operation of the steering wheel based on an input torque including at least one of the steering torque and the first component. The third computing unit computes the second component of the command value through feedback control for matching the actual rotational angle of the rotating body with the target rotational angle. The fourth calculation unit calculates an ideal axial force that is an ideal axial force that acts on the steered wheels based on the target rotation angle and that is reflected in the input torque. The fifth calculation unit follows the crossing gradient based on the ideal axial force based on the neutral value of the ideal axial force corresponding to the straight traveling state of the vehicle according to the crossing gradient that is a gradient in the direction perpendicular to the road line. In a specific direction that is opposite to the side where the vehicle deviates from the road due to the cross slope.

When the vehicle travels on a road having a cross slope, if the steering wheel is not operated, the vehicle may deviate from the road due to the cross slope of the road.
In this regard, according to the steering control device described above, when the vehicle is traveling on a road having a crossing gradient, the ideal axial force is in a straight traveling state according to the crossing gradient that is a gradient in a direction perpendicular to the road line of the road. With respect to the neutral value of the ideal axial force corresponding to, the vehicle is offset in the direction along the cross gradient to the side opposite to the side where the vehicle deviates from the road due to the cross gradient.

  For this reason, when the vehicle is traveling on a road having a crossing gradient, even when the steering wheel is not operated, the ideal axial force and thus the input torque does not become zero, and the target rotation angle is calculated based on the input torque. The Then, through the feedback control that matches the rotation angle of the rotator with the target rotation angle, the rotation angle of the rotator according to the crossing gradient of the road, and thus the steering angle that is the rotation angle of the steering wheel is realized. At this time, the rotation angle of the rotating body and the steering angle of the steering wheel are directions along the crossing gradient with respect to a neutral value corresponding to the straight traveling state of the vehicle. The angle is offset in a specific direction that is opposite to the side deviating from. Therefore, when the vehicle travels on a road having a crossing gradient, even if no steering torque is applied to the steering wheel, a steering angle corresponding to the crossing gradient of the road is realized, thereby obtaining an appropriate steering feeling. be able to.

  In the steering control device described above, the fifth arithmetic unit travels on a first ramp that is a curved road having a cross slope based on a state quantity that reflects the turning motion of the vehicle. When the determination is made, the ideal axial force is in the specific direction based on the neutral value of the ideal axial force corresponding to the vehicle straight traveling state according to a crossing gradient that is a gradient in a direction perpendicular to the road line. It is preferable that the first ramp is offset to the side where the crossing gradient decreases.

  The ideal axial force calculated based on the target rotation angle is an axial force that ignores the balance of forces acting on the vehicle. For this reason, when the vehicle travels on the first slope which is a curved road, the steering angle of the steering wheel is the first slope unless the driver continues steering by applying steering torque to the steering wheel. It is not an angle corresponding to the crossing gradient of the vehicle, but is maintained at a neutral angle corresponding to the straight traveling state of the vehicle. Therefore, when the vehicle is traveling on the first slope, if the steering torque is not applied to the steering wheel and the steering is not maintained, the vehicle cannot continue traveling along the first slope and goes straight ahead. There is a risk of traveling in a form of running up the first slope toward the outside of the curve.

  In this respect, according to the steering control device described above, through the feedback control that matches the rotation angle of the rotating body with the target rotation angle, the rotation angle of the rotating body and the steering angle of the steering wheel are neutral with respect to the straight traveling state of the vehicle. Using the value as a reference, the angle is offset to the side opposite to the side where the vehicle deviates from the road due to the crossing gradient, that is, the side where the crossing gradient of the first ramp decreases. Therefore, when the vehicle travels on the first slope, even if no steering torque is applied to the steering wheel, the steering angle corresponding to the cross slope of the first slope is realized, so that appropriate steering is achieved. Feeling can be obtained.

  In the steering control device described above, the fifth computing unit travels on a second ramp that is a straight road having a cross slope based on a state quantity that reflects the turning motion of the vehicle. When the determination is made, the ideal axial force is in the specific direction based on the neutral value of the ideal axial force corresponding to the vehicle straight traveling state according to a crossing gradient that is a gradient in a direction perpendicular to the road line. It is preferable to offset to the side where the crossing gradient of the second ramp increases.

  When the vehicle travels on the second slope, which is a straight road, the vehicle travels along the second slope 91b unless the driver continues steering by applying steering torque to the steering wheel. It cannot be maintained, and as the vehicle advances, the vehicle gradually travels toward the lower side of the second ramp. This is because the vehicle is affected by the cross slope of the second ramp.

  In this respect, according to the steering control device described above, through the feedback control that matches the rotation angle of the rotating body with the target rotation angle, the rotation angle of the rotating body and the steering angle of the steering wheel are neutral with respect to the straight traveling state of the vehicle. Based on the value, the angle is offset to the side opposite to the side where the vehicle deviates from the road due to the crossing gradient, that is, the side where the crossing gradient of the second ramp increases. Therefore, when the vehicle travels on the second slope, even if no steering torque is applied to the steering wheel, a steering angle corresponding to the cross slope of the second slope is realized, thereby achieving appropriate steering. Feeling can be obtained.

  In the steering control device described above, the fifth calculation unit corrects the target rotation angle used for calculating the ideal axial force in the fourth calculation unit according to the transverse gradient. It is preferable to offset the ideal axial force in the specific direction by adding an angle.

  According to the steering control device described above, the ideal axial force is calculated by adding the correction angle calculated in accordance with the road crossing gradient to the target rotation angle used for calculating the ideal axial force in the fourth calculation unit. Can be offset in the specific direction described above. This is based on the fact that the ideal axial force calculated by the fourth calculation unit also changes according to the correction angle by changing the target rotation angle by the correction angle with reference to the neutral angle corresponding to the straight traveling state of the vehicle. .

  In the steering control device, the fifth calculation unit adds a correction axial force calculated according to the crossing gradient to the ideal axial force calculated by the fourth calculation unit. The ideal axial force is preferably offset in the specific direction.

  According to the steering control device described above, the ideal axial force is determined by adding the corrected axial force calculated according to the road crossing gradient to the ideal axial force calculated by the fourth calculation unit. Can be offset in the direction. The final axial force obtained by adding the correction axial force to the ideal axial force calculated by the fourth calculation unit is reflected in the input torque.

  In the above steering control device, the fifth calculation unit is a curved line having a transverse gradient when the yaw rate as the state quantity reflecting the turning motion of the vehicle detected through the sensor is equal to or greater than a threshold value. When the yaw rate is less than the threshold value, the vehicle travels on the second ramp which is a straight road having a cross slope. It is preferable to determine that it is.

  The yaw rate when the vehicle is traveling on the first ramp that is a curved road having a cross slope is when the vehicle is traveling on the second ramp that is a straight road having a cross slope Greater than the yaw rate. Therefore, as with the steering control device described above, it can be determined whether the vehicle is traveling on the first ramp or the second ramp based on the yaw rate.

  In the above steering control device, a sixth calculation unit that calculates an axial force acting on the steered wheels based on a state quantity reflecting a vehicle behavior or a road surface state as an estimated axial force, the ideal axial force, and the estimated shaft A seventh calculation unit that calculates a final axial force to be reflected in the input torque by adding a value obtained by multiplying a force by a distribution ratio individually set according to the cross slope; You may have.

  The actual vehicle behavior or road surface state is not reflected in the ideal axial force, whereas the actual vehicle behavior or road surface state is reflected in the estimated axial force. Therefore, as in the steering control device described above, by changing the ratio of the ideal axial force and the estimated axial force in the final axial force reflected in the input torque according to the crossing gradient of the road, the crossing gradient A more appropriate target rotation angle according to the above, and consequently the steering angle of the steering wheel is realized. Therefore, the driver can steer more naturally.

  In the steering control device, the seventh calculation unit recognizes the cross gradient based on a gravity component in a direction along the cross gradient calculated from a lateral acceleration, a yaw rate, and a vehicle speed, and an absolute value of the gravity component It is preferable to set the distribution ratio so that the ratio of the estimated axial force to the final axial force becomes larger as the value of becomes larger.

  The gravity component in the direction along the road crossing gradient reflects the degree of road crossing gradient. And according to said steering control apparatus, an actual road surface state is reflected more strongly by final axial force, so that the absolute value of a gravity component becomes large, ie, the crossing gradient of a road becomes large. For this reason, a more appropriate target rotation angle according to the crossing gradient, and consequently, the steering angle of the steering wheel is realized.

  In the steering control device, the seventh calculation unit recognizes the crossing gradient based on an axial force deviation that is a difference between the ideal axial force and the estimated axial force, and an absolute value of the axial force deviation is large. It is preferable to set the distribution ratio so that the proportion of the estimated axial force in the final axial force is larger.

  The road surface condition is reflected in the axial force deviation between the ideal axial force and the estimated axial force. The degree of road crossing gradient is also reflected in the axial force deviation as the road surface condition. And according to said steering control apparatus, an actual road surface condition is reflected more strongly by final axial force, so that the absolute value of axial force deviation becomes large, ie, the crossing gradient of a road becomes large. For this reason, a more appropriate target rotation angle according to the crossing gradient, and consequently, the steering angle of the steering wheel is realized.

  According to the steering control device of the present invention, an appropriate steering feeling can be obtained even on an inclined road.

1 is a configuration diagram of a steer-by-wire steering device on which a first embodiment of a steering control device is mounted. The control block diagram of the control apparatus in 1st Embodiment. The control block diagram of the target rudder angle calculating part in 1st Embodiment. The control block diagram of the vehicle model in 1st Embodiment. (A) is a schematic diagram which shows the travel locus | trajectory of the vehicle which drive | works a 1st slope, (b) is a schematic diagram which shows the travel locus | trajectory of the vehicle which drive | works a 2nd slope. The schematic diagram of the vehicle explaining the force which acts on the vehicle in 1st Embodiment. The control block diagram of the correction | amendment process part in 1st Embodiment. (A) is a graph showing a first map showing the relationship between the gravity component due to the road surface gradient and the correction amount in the first embodiment, and (b) is a gravity component due to the road surface gradient in the first embodiment. The graph which shows the 2nd map which shows the relationship between a correction amount. (A) is a graph which shows the relationship between the target pinion angle and ideal axial force in 1st Embodiment, (b) is a graph which shows the relationship between the steering angle and steering torque in 1st Embodiment. The control block of the ideal axial force calculating part in 2nd Embodiment of a steering control apparatus. The control block diagram of the correction | amendment process part in 2nd Embodiment. The control block diagram of the axial force distribution calculating part in 3rd Embodiment of a steering control apparatus. The control block diagram of the axial force distribution calculating part in 4th Embodiment of a steering control apparatus. The control block diagram of the axial force distribution calculating part in 5th Embodiment of a steering control apparatus. The control block diagram of the axial force distribution calculating part in 6th Embodiment of a steering control apparatus.

<First Embodiment>
A first embodiment in which the steering control device is applied to a steer-by-wire steering device will be described.

As shown in FIG. 1, the vehicle steering apparatus 10 includes a steering shaft 12 connected to a steering wheel 11. The steering shaft 12 constitutes a steering mechanism. Further, the steering device 10 has a steered shaft 14 that extends along the vehicle width direction (left-right direction in FIG. 1). Left and right steered wheels 16 and 16 are connected to both ends of the steered shaft 14 via tie rods 15 and 15, respectively. Turning shaft 14 by linear movement, the steering angle theta _w of the steered wheels 16, 16 is changed.

<Configuration for generating steering reaction force: reaction force unit>
Further, the steering apparatus 10 includes a reaction force motor 31, a speed reduction mechanism 32, a rotation angle sensor 33, and a torque sensor 34 as a configuration for generating a steering reaction force. Incidentally, the steering reaction force refers to a force (torque) acting in a direction opposite to the direction in which the driver operates the steering wheel 11. By applying the steering reaction force to the steering wheel 11, it is possible to give the driver a moderate feeling of response.

  The reaction force motor 31 is a generation source of the steering reaction force. As the reaction force motor 31, for example, a three-phase (U, V, W) brushless motor is employed. The reaction force motor 31 (more precisely, its rotating shaft) is connected to the steering shaft 12 via a speed reduction mechanism 32. The torque of the reaction force motor 31 is applied to the steering shaft 12 as a steering reaction force.

The rotation angle sensor 33 is provided in the reaction force motor 31. Rotation angle sensor 33 detects the rotation angle theta _a reaction force motor 31. Rotation angle theta _a reaction force motor 31 is used in the calculation of the steering angle (steering angle) theta _s. The reaction force motor 31 and the steering shaft 12 are linked via a speed reduction mechanism 32. Therefore, the rotation angle of the rotation angle theta _a and the steering shaft 12 of the reaction force motor 31, between the steering angle theta _s is therefore the rotation angle of the steering wheel 11 are correlated. Therefore, the steering angle θ _s can be obtained based on the rotation angle θ _a of the reaction force motor 31.

The torque sensor 34 detects the steering torque T _h applied to the steering shaft 12 through a rotational operation of the steering wheel 11. The torque sensor 34 is provided in a portion of the steering shaft 12 closer to the steering wheel 11 than the speed reduction mechanism 32.

<Configuration for generating steering force: Steering unit>
Further, the steering device 10 includes a steering motor 41, a speed reduction mechanism 42, and a rotation angle sensor 43 as a configuration for generating a steering force that is power for turning the steered wheels 16 and 16. Yes.

  The steered motor 41 is a source of turning force. As the steered motor 41, for example, a three-phase brushless motor is employed. The steered motor 41 (more precisely, its rotating shaft) is connected to a pinion shaft 44 via a speed reduction mechanism 42. The pinion teeth 44 a of the pinion shaft 44 are meshed with the rack teeth 14 b of the steered shaft 14. The torque of the turning motor 41 is applied to the turning shaft 14 through the pinion shaft 44 as a turning force. In accordance with the rotation of the turning motor 41, the turning shaft 14 moves along the vehicle width direction (left-right direction in the figure).

The rotation angle sensor 43 is provided in the steering motor 41. Rotation angle sensor 43 detects the rotation angle theta _b steering motors 41.
Incidentally, the steering device 10 has a pinion shaft 13. The pinion shaft 13 is provided so as to intersect the steered shaft 14. The pinion teeth 13 a of the pinion shaft 13 are meshed with the rack teeth 14 a of the steered shaft 14. The reason for providing the pinion shaft 13 is to support the steered shaft 14 together with the pinion shaft 44 inside a housing (not shown). That is, the steering shaft 14 is supported by a support mechanism (not shown) provided in the steering device 10 so as to be movable along the axial direction, and is pressed toward the pinion shafts 13 and 44. Thereby, the steered shaft 14 is supported inside the housing. However, another support mechanism that supports the steered shaft 14 on the housing without using the pinion shaft 13 may be provided.

<Control device>
In addition, the steering device 10 has a control device 50. The control device 50 controls the reaction force motor 31 and the steered motor 41 based on the detection results of various sensors. The sensors include a vehicle speed sensor 501, a lateral acceleration sensor 502, and a yaw rate sensor 503 in addition to the rotation angle sensor 33, torque sensor 34, and rotation angle sensor 43 described above. The vehicle speed sensor 501 is provided in the vehicle and detects a vehicle speed V that is a traveling speed of the vehicle. Lateral acceleration sensor 502 detects lateral acceleration LA acting on the vehicle. The lateral acceleration LA refers to acceleration in a direction orthogonal to the traveling direction of the vehicle when the vehicle turns. The yaw rate sensor 503 detects the yaw rate YR acting on the vehicle. The yaw rate YR refers to the rotational angular velocity around the vertical axis that passes through the center of gravity of the vehicle.

Controller 50 executes the reaction force control for generating the steering reaction force corresponding to the steering torque T _h through the drive control of the reaction motor 31. Controller 50 calculates the target steering reaction force based on the steering torque T _h and the vehicle speed V, the target steering reaction force this calculation, calculates a target steering angle of the steering wheel 11 based on the steering torque T _h and the vehicle speed V. The control device 50 calculates the steering angle correction amount through feedback control of the steering angle θ _s that is executed so that the actual steering angle θ _s follows the target steering angle, and the calculated steering angle correction amount is calculated as the target steering reaction amount. The steering reaction force command value is calculated by adding to the force. The control device 50 supplies the reaction force motor 31 with a current required to generate a steering reaction force corresponding to the steering reaction force command value.

The control device 50 performs steering control for turning the steered wheels 16 and 16 according to the steering state through drive control of the steered motor 41. The control device 50 calculates the pinion angle θ _p that is the actual rotation angle of the pinion shaft 44 based on the rotation angle θ _b of the steering motor 41 detected through the rotation angle sensor 43. The pinion angle theta _p is a value that reflects the turning angle theta _w of the steered wheels 16, 16. The control device 50 calculates the target pinion angle using the target steering angle described above. The control unit 50 obtains the deviation of the actual pinion angle theta _p target pinion angle, and controls the power supply to the steering motor 41 so as to eliminate the deviation.

<Detailed configuration of control device>
Next, the control device 50 will be described in detail.
As shown in FIG. 2, the control device 50 includes a reaction force control unit 50 a that executes reaction force control, and a steering control unit 50 b that executes turning control.

<Reaction force control unit>
The reaction force control unit 50 a includes a target steering reaction force calculation unit 51, a target steering angle calculation unit 52, a steering angle calculation unit 53, a steering angle feedback control unit 54, an adder 55, and an energization control unit 56.

The target steering reaction force calculation unit 51 calculates a target steering reaction force T ₁ ^* based on the steering torque _Th and the vehicle speed V.
The target rudder angle calculation unit 52 calculates the target rudder angle θ ^* of the steering wheel 11 using the target steering reaction force T ₁ ^* , the steering torque _Th, and the vehicle speed V. Target steering angle calculating section 52, when the sum of the target steering reaction force T ₁ ^* and the steering torque T _h and the input torque, have the ideal model to determine the ideal steering angle (steering angle) based on the input torque doing. This ideal model is based on the assumption that a steering device in which the steering wheel 11 and the steered wheels 16 and 16 are mechanically connected with each other. It is modeled by. The target rudder angle calculation unit 52 obtains an input torque by adding the target steering reaction force T ₁ ^* and the steering torque _Th, and based on this input torque, the target rudder angle θ ^* (target steering angle) Is calculated.

The steering angle calculator 53 calculates the actual steering angle θ _s of the steering wheel 11 based on the rotation angle θ _a of the reaction force motor 31 detected through the rotation angle sensor 33. Steering angle feedback control section 54 calculates the actual steering angle theta _s steering angle correction amount through feedback control of the steering angle theta _s in order to follow the target steering angle theta ^* a T ₂ ^*. The adder 55 calculates the steering reaction force command value T ^* by the target steering reaction force T ₁ ^* adds the steering angle correction amount T ₂ ^*.

The energization control unit 56 supplies power corresponding to the steering reaction force command value T ^* to the reaction force motor 31. Specifically, the energization control unit 56 calculates a current command value for the reaction force motor 31 based on the steering reaction force command value T ^* . Further, power supply controller 56 through the current sensor 57 provided in the feed path for the reaction force motor 31, to detect the actual current values I _a generated to the power supply path. This current value _Ia is a value of an actual current supplied to the reaction force motor 31. The power supply controller 56 obtains the deviation of the actual current value I _a current command value, and controls the power supply to the reaction force motor 31 so as to eliminate the deviation (feedback control of the current I _a). Thereby, the reaction force motor 31 generates torque according to the steering reaction force command value T ^* . It is possible to give the driver an appropriate feeling of response according to the road surface reaction force.

<Steering control unit>
As shown in FIG. 2, the steering control unit 50 b includes a pinion angle calculation unit 61, a steering angle ratio change control unit 62, a differential steering control unit 63, a pinion angle feedback control unit 64, and an energization control unit 65. Yes.

Pinion angle calculating section 61 calculates the pinion angle theta _p is the actual rotation angle of the pinion shaft 44 based on the rotation angle theta _b of the steering motor 41 which is detected through the rotational angle sensor 43. As described above, the steered motor 41 and the pinion shaft 44 are linked via the speed reduction mechanism 42. Therefore, there is a correlation between the rotation angle theta _b and the pinion angle theta _p of the steering motor 41. Using this correlation can be obtained pinion angle theta _p from the rotation angle theta _b steering motors 41. Further, as described above, the pinion shaft 44 is engaged with the steered shaft 14. Therefore, there is also a correlation between the pinion angle theta _p and the amount of movement of the steered shaft 14. That is, the pinion angle θ _p is a value reflecting the steered angle θ _w of the steered wheels 16 and 16.

The steering angle ratio change control unit 62 sets a steering angle ratio that is a ratio of the steering angle θ _w to the steering angle θ _s according to the traveling state of the vehicle (for example, the vehicle speed V), and sets the steering angle ratio to this set steering angle ratio. The target pinion angle is calculated accordingly. Steering ratio change control unit 62, so as to increase the steering angle theta _w Gayori for steering angle theta _s as the vehicle speed V is slow, and the steering angle to the steering angle theta _s as the vehicle speed V becomes faster theta _w is smaller The target pinion angle θ _p ^* is calculated as follows. The steering angle ratio change control unit 62 calculates a correction angle for the target steering angle θ ^* in order to realize a steering angle ratio that is set according to the traveling state of the vehicle, and uses the calculated correction angle as the target steering angle. By adding to θ ^* , the target pinion angle θ _p ^* corresponding to the steering angle ratio is calculated.

The differential steering control unit 63 calculates a change speed (steering speed) of the target pinion angle θ _p ^* by differentiating the target pinion angle θ _p ^* . Further, the differential steering control unit 63 calculates the correction angle to the target pinion angle theta _p ^* by multiplying the gain with a change rate of the target pinion angle theta _p ^*. Differential steering control unit 63 calculates the final target pinion angle theta _p ^* by adding the correction angle to the target pinion angle theta _p ^*. As the phase of the target pinion angle θ _p ^* calculated by the steering angle ratio change control unit 62 is advanced, the steering delay is improved. That is, the steering response is ensured according to the steering speed.

Pinion angle feedback control section 64, the actual pinion angle theta _p, through the final target pinion angle theta _p ^* in order to follow the pinion angle theta _p of feedback control is calculated by differentiating the steering control section 63 (PID control) The pinion angle command value T _p ^* is calculated.

The energization control unit 65 supplies power corresponding to the pinion angle command value T _p ^* to the steering motor 41. Specifically, the energization control unit 65 calculates a current command value for the steered motor 41 based on the pinion angle command value T _p ^* . Further, power supply controller 65, through the current sensor 66 provided in the power feeding path for the steering motor 41, to detect the actual current value I _b occurring to the power supply path. This current value _Ib is a value of an actual current supplied to the steered motor 41. The power supply controller 65 obtains the deviation of the actual current value I _b between the current command value, and controls the power supply to the steering motor 41 so as to eliminate the deviation (feedback control of the current I _b). Thereby, the steered motor 41 rotates by an angle corresponding to the pinion angle command value T _p ^* .

<Target rudder angle calculation unit>
Next, the target rudder angle calculation unit 52 will be described in detail.
As described above, the target steering angle calculating section 52 calculates the target steering angle theta ^* based from the input torque target steering is the sum of the reaction force T ₁ ^* and the steering torque T _h the ideal model. This ideal model is a model that utilizes the fact that the input torque T _in ^* as the torque applied to the steering shaft 12 is expressed by the following equation (1).

T _in ^* = Jθ ^{* ″} + Cθ ^{* ′} + Kθ ^* (1)
However, "J" is the moment of inertia of the steering wheel 11 and the steering shaft 12, "C" is a viscosity coefficient (friction coefficient) corresponding to friction with respect to the housing of the steered shaft 14, and "K" is the steering wheel 11 and the steering shaft. This is a spring coefficient when 12 is regarded as a spring.

As can be seen from equation (1), the input torque T _in ^* is target steering angle theta ^* a second-order time differential value theta ^{* ''} to a value obtained by multiplying the inertia moment J, the target steering angle theta ^* a first-order time differential value It is obtained by adding a value obtained by multiplying the viscosity coefficient C by θ ^* ′ and a value obtained by multiplying the target steering angle θ ^* by the spring coefficient K. The target rudder angle calculation unit 52 calculates the target rudder angle θ ^* according to an ideal model based on Expression (1).

As shown in FIG. 3, the ideal model based on Expression (1) is divided into a steering model 71 and a vehicle model 72.
The steering model 71 is tuned according to the characteristics of each component of the steering device 10 such as the steering shaft 12 and the reaction force motor 31. The steering model 71 includes an adder 73, a subtractor 74, an inertia model 75, a first integrator 76, a second integrator 77, and a viscosity model 78.

The adder 73 calculates the input torque _{T in} ^* by adding the target steering reaction force _T ^{1 *} and the steering torque _{T h.}
The subtracter 74 calculates a final input torque T _in ^* by subtracting a viscosity component T _vi ^* and a spring component T _sp ^*, which will be described later, from the input torque T _in ^* calculated by the adder 73, respectively.

The inertia model 75 functions as an inertia control calculation unit corresponding to the inertia term of Expression (1). The inertia model 75 calculates the steering angular acceleration α ^* by multiplying the final input torque T _in ^* calculated by the subtracter 74 by the inverse of the inertia moment J.

The first integrator 76 calculates the steering angular velocity ω ^* by integrating the steering angular acceleration α ^* calculated by the inertia model 75.
The second integrator 77 further calculates the target steering angle θ ^* by further integrating the steering angular velocity ω ^* calculated by the first integrator 76. The target rudder angle θ ^* is an ideal rotation angle of the steering wheel 11 (steering shaft 12) based on the steering model 71.

The viscosity model 78 functions as a viscosity control calculation unit corresponding to the viscosity term of Expression (1). The viscosity model 78 calculates the viscosity component T _vi ^* of the input torque T _in ^* by multiplying the steering angular velocity ω ^* calculated by the first integrator 76 by the viscosity coefficient C.

The vehicle model 72 is tuned according to the characteristics of the vehicle on which the steering device 10 is mounted. The vehicle-side characteristics that affect the steering characteristics are determined by, for example, the specifications of the suspension and wheel alignment, the grip force (friction force) of the steered wheels 16 and 16, and the like. The vehicle model 72 functions as a spring characteristic control calculation unit corresponding to the spring term of Expression (1). The vehicle model 72 calculates the spring component T _sp ^* (torque) of the input torque T _in ^* by multiplying the target steering angle θ ^* calculated by the second integrator 77 by the spring coefficient K.

According to the target rudder angle calculation unit 52 configured as described above, the input torque T _in ^* and the target rudder are adjusted by adjusting the moment of inertia J and the viscosity coefficient C of the steering model 71 and the spring coefficient K of the vehicle model 72, respectively. By directly tuning the relationship with the angle θ ^* , it is possible to realize a desired steering characteristic.

Further, the target pinion angle θ _p ^* is calculated using the target steering angle θ ^* calculated from the input torque T _in ^{* based} on the steering model 71 and the vehicle model 72. Then, feedback control is performed so that the actual pinion angle θ _p matches the target pinion angle θ _p ^* . As described above, there is a correlation between the pinion angle theta _p and the steered angle theta _w of the steered wheels 16, 16. For this reason, the steering operation of the steered wheels 16 and 16 according to the input torque T _in ^* is also determined by the steering model 71 and the vehicle model 72. That is, the steering feeling of the vehicle is determined by the steering model 71 and the vehicle model 72. Therefore, it is possible to realize a desired steering feeling by adjusting the steering model 71 and the vehicle model 72.

However, in the control device 50 configured as described above, the steering reaction force (the response felt through the steering) is only in accordance with the target steering angle θ ^* . That is, the steering reaction force does not change depending on the vehicle behavior or the road surface condition (such as slipperiness of the road surface). For this reason, it is difficult for the driver to grasp the vehicle behavior or the road surface state through the steering reaction force. Therefore, in the present embodiment, the vehicle model 72 is configured as follows based on the viewpoint of eliminating such a concern.

<Vehicle model>
As shown in FIG. 4, the vehicle model 72 includes an ideal axial force calculation unit 81, an estimated axial force calculation unit 82, an axial force distribution calculation unit 83, and a conversion unit 84.

The ideal axial force calculation unit 81 calculates an ideal axial force F1 that is an ideal value of the axial force acting on the steered shaft 14 through the steered wheels 16 and 16 based on the target pinion angle θ _p ^* . The ideal axial force calculation unit 81 calculates an ideal axial force F1 using an ideal axial force map stored in a storage device (not shown) of the control device 50. The ideal axial force F1 increases as the absolute value of the target pinion angle θ _p ^* (or the target turning angle obtained by multiplying the target pinion angle θ _p ^* by a predetermined conversion factor) increases, and the vehicle speed V decreases. The larger the absolute value is set. The vehicle speed V does not necessarily have to be taken into consideration.

Estimated axial force calculating unit 82, based on the current value I _b of the steering motor 41, calculates the estimated axial force F2 (road surface reaction force) acting on the steering shaft 14. Here, the current value I _b of the turning motor 41, the actual pinion angle between the target pinion angle theta _p ^* disturbance in accordance with the road surface condition (road surface friction resistance) due to acting on the steered wheels 16 theta _p Changes due to the difference between That is, the current value I _b of the steering motor 41, the actual road surface reaction force acting on the steered wheels 16, 16 is reflected. Therefore, it is possible to calculate the axial force that reflects the influence of the road surface state based on the current value I _b of the turning motor 41. Estimated axial force F2 is obtained by multiplying the gain is a coefficient corresponding to the vehicle speed V to a current value I _b of the turning motor 41.

The axial force distribution calculation unit 83 adds the values obtained by multiplying the ideal axial force F1 and the estimated axial force F2 by individually set distribution ratios (gains), thereby obtaining a spring component for the input torque T _in ^* . The final axial force F _sp used for calculating T _sp ^* is calculated. The distribution ratio is set according to various state quantities that reflect the vehicle behavior, the road surface state, or the steering state.

The conversion unit 84 calculates (converts) the spring component T _sp ^* with respect to the input torque T _in ^* based on the final axial force F _sp calculated by the axial force distribution calculation unit 83. By reflecting the spring component T _sp ^* based on this final axial force F _sp to the input torque T _in ^* , it is possible to apply a steering reaction force according to the vehicle behavior or the road surface condition to the steering wheel 11. Become.

<When the vehicle travels on a ramp>
Here, a case where the vehicle travels on a curved slope having a crossing gradient (gradient in a direction perpendicular to the road line) will be considered.

First, as a comparative example, a case will be described in which a vehicle equipped with an electric power steering device as a steering device that does not have a feedback function of the steering angle θ _s and a feedback mechanism of the pinion angle θ _p travels on a curved slope. Here, it is assumed that the steering wheel 11 and the steered wheel 16 are mechanically connected. In this case, the steering position of the steering wheel and the steered position of the steered wheels 16 are inclined on the slope even when the steering wheel 11 is not steered by the driver due to the balance of forces (gravity and centrifugal force) acting on the vehicle. It changes toward the position according to. For this reason, when the vehicle is traveling on a curved ramp, the driver does not need to steer the steering wheel 11 greatly.

On the other hand, when a vehicle equipped with the steering device 10 having the feedback function of the steering angle θ _{s and} the feedback function of the pinion angle θ _p travels on the slope, the following traveling state is assumed. Here, a case where the vehicle travels on a first slope (so-called bank road) extending in a curved line and a second slope (so-called cant road) extending in a straight line will be considered.

  As shown in FIG. 5A, a case where the vehicle 90 travels on the first ramp 91a will be described first. Here, the first ramp 91 a curves to the left with respect to the traveling direction of the vehicle 90. Further, the road surface of the first inclined path 91a is inclined so as to gradually decrease from the outside to the inside of the curve in the direction along the cross gradient.

In this case, if the driver does not continue to hold the steering wheel 11 by applying a force (steering torque T _h ), as shown by a two-dot chain arrow B1 in FIG. Traveling straight along the route 92 on the first slope 91a cannot be maintained, and the first slope 91a runs toward the outside.

This is for the following reason. That is, the ideal axial force F1 calculated based on the target pinion angle θ _p ^* is an axial force that ignores the balance of forces acting on the vehicle. Therefore, when the vehicle travels on a curved slope under reaction force control based on the ideal axial force F1, the steering position of the steering wheel 11 must be applied unless the driver applies the steering torque _Th to the steering wheel 11. And the steered position of the steered wheel 16 does not become a position corresponding to the slope (crossing gradient) of the ramp, but is returned to the neutral position.

  Next, as shown in FIG. 5B, a case where the vehicle 90 travels on the second ramp 91b will be described. The road surface of the second inclined path 91b is inclined so as to gradually decrease from the right side to the left side with respect to the traveling direction of the vehicle 90.

  In this case, if the driver does not continue to hold the steering wheel 11 by applying a force to the steering wheel 11, as shown by the two-dot chain line arrow B2 in FIG. Traveling along the route 92 cannot be maintained, and the vehicle travels in such a manner that the height of the second inclined road 91b gradually decreases toward the lower side as it moves forward. This is because the vehicle 90 is affected by the inclination of the road surface.

  Thus, whether the vehicle 90 travels on the first slope 91a or the second slope 91b, the driver steers the vehicle 90 to travel along the route 92. It is necessary to continue to hold the wheel 11 by applying a force according to the inclination of the road surface. For this reason, there is a possibility that the driver cannot obtain an appropriate steering feeling.

Therefore, in the present embodiment, when the vehicle travels on the slope, the steering position (steering angle θ _s ) of the steering wheel 11 and the steered position (steering angle θ _w ) of the steered wheels 16 are set to the slope of the slope. In order to obtain the corresponding position, the following configuration is adopted as the vehicle model 72.

That is, as indicated by a two-dot chain line in FIG. 4, the vehicle model 72 has a correction processing unit 85. The correction processing unit 85 corrects the target pinion angle θ _p ^* according to the degree of inclination of the slope. The target pinion angle θ _p ^* to be corrected is used for calculating the ideal axial force F1 in the ideal axial force calculating unit 81. As the target pinion angle θ _p ^* to be corrected, either a value calculated by the steering angle ratio change control unit 62 or a value calculated by the differential steering control unit 63 may be used. In this embodiment, the target pinion angle θ _p ^* calculated by the steering angle ratio change control unit 62 is used.

The correction processing unit 85 recognizes the slope of the slope based on the component in the direction along the road gradient (the vehicle width direction) of gravity acting on the vehicle on the slope, and sets the target according to the recognized slope. The pinion angle θ _p ^* is corrected.

As shown in FIG. 6, the gravity component G _a is a component of along the road gradient of the gravitational force acting on the vehicle in the slope road direction is expressed by the following equation (2).
G _a = G _b · sin β (2)
However, “G _b ” is the gravitational acceleration, and “β” is the inclination angle of the road surface on the slope with respect to the horizontal plane.

According to equation (2), a larger value is gravity component G _a higher tilt angle β of the road surface becomes large, the inclination angle β is gravity component G _a more reduced, it is seen that becomes a smaller value. That is, the gravity component G _a is a value that reflects the degree of inclination of the ramp.

Correction processing unit 85 is actually calculates based gravity component G _a in equation (3).
G _a = LA−YR · V (3)
However, “LA” is the lateral acceleration, “V” is the vehicle speed, and “YR” is the yaw rate.

Incidentally, the expression (3) is derived based on the fact that the lateral acceleration LA is expressed by the following expression (4) and the centrifugal acceleration α acting on the vehicle is expressed by the following expression (5). That is, by applying equation (5) into equation (4), Equation (3) is obtained by solving the equation (4) for the gravity component _{G a.}

LA = α + G _a (4)
α = YR · V (5)
However, “α” is the centrifugal acceleration, “Ga” is the gravity component in the direction along the road gradient acting on the vehicle, “YR” is the yaw rate, and “V” is the vehicle speed.

<Correction processor>
Next, the configuration of the correction processing unit 85 will be described in detail.
As illustrated in FIG. 7, the correction processing unit 85 includes a multiplier 101, a subtracter 102, a correction amount calculation unit 103, a gain calculation unit 104, a multiplier 105, and an adder 106.

  The multiplier 101 multiplies the yaw rate YR detected through the yaw rate sensor 503 by the vehicle speed V detected through the vehicle speed sensor 501, thereby calculating the centrifugal acceleration α. This is based on the previous equation (5).

Subtractor 102, from the lateral acceleration LA detected through the lateral acceleration sensor 502, by subtracting the centrifugal acceleration α which is calculated by the multiplier 101 calculates the gravity component G _a by road gradient. This is based on the above formulas (3) and (5).

The correction amount calculator 103 calculates a correction amount θ _c ^* (correction angle) with respect to the target pinion angle θ _p ^* based on the gravity component G _a due to the road surface gradient calculated by the subtractor 102 and the yaw rate YR detected through the yaw rate sensor 503. ) Is calculated.

The gain calculation unit 104 calculates a gain G _c for the correction amount θ _c ^* based on the vehicle speed V detected through the vehicle speed sensor 501. Gain calculating section 104 calculates more gain G _c of greater value as the vehicle speed V becomes faster.

The multiplier 105 multiplies the correction amount θ _c ^* calculated by the correction amount calculation unit 103 and the gain G _c calculated by the gain calculation unit 104 to calculate the final correction amount θ _c ^* . .

The adder 106 corrects the target pinion angle θ _p ^* used for the calculation of the ideal axial force F 1, and the final correction amount θ _c ^* calculated by the target pinion angle θ _p ^* and the multiplier 105 ^. Is added to the ideal axial force calculation unit 81 to calculate the final target pinion angle θ _p ^* used for calculating the ideal axial force F1.

<Correction amount calculation map>
The correction amount calculation unit 103 calculates the correction amount θ _c ^* using the first map M1 and the second map M2. The first map M1 and the second map M2 are stored in a storage device (not shown) of the control device 50.

As shown in FIG. 8A, the first map M1 is a map in which the horizontal axis represents the gravity component Ga due to the road surface gradient and the vertical axis represents the correction amount θ _c ^*, and the gravity map Ga and the correction due to the road surface gradient are corrected. Defines the relationship with the quantity θ _c ^* . The first map M1 has the following characteristics. That is, when the gravity component Ga is a positive value, the correction amount θ _c ^* is a positive value. When the gravity component Ga is a positive value, the value of the correction amount θ _c ^* increases exponentially in the positive direction as the absolute value of the gravity component Ga increases. Further, when the gravity component Ga is a negative value, the correction amount θ _c ^* is a negative value. When the gravity component Ga is a negative value, the value of the correction amount θ _c ^* increases exponentially in the negative direction as the absolute value of the gravity component Ga increases.

As shown in FIG. 8B, the second map M2 is also a map with the horizontal axis representing the gravity component G _a due to the road surface gradient and the vertical axis representing the correction amount θ _c ^*, and the gravity component G _a due to the road surface gradient. And the correction amount θ _c ^* are defined. The second map M2 has the following characteristics. That is, when the gravity component Ga is a positive value, the correction amount θ _c ^* is a negative value. When the gravity component Ga is a positive value, the value of the correction amount θ _c ^* increases exponentially in the negative direction with respect to the increase in the absolute value of the gravity component Ga, and eventually becomes a negative value −P _c . Converge (become peak). Further, when the gravity component Ga is a negative value, the correction amount θ _c ^* is a positive value. When the gravity component Ga is a negative value, the correction amount θ _c ^* increases exponentially in the positive direction as the absolute value of the gravity component Ga increases, and eventually converges to a positive value + P _c . To do.

When the yaw rate YR is greater than or equal to the threshold YR _th , the correction amount calculation unit 103 uses the first map M1 shown in FIG. 8A, and when the yaw rate YR is less than the threshold YR _th. Uses the second map M2 shown in FIG. 8 (b). The threshold value YR _th is set to distinguish whether the vehicle is traveling on the curved first slope 91a or the straight second slope 91b. That is, the yaw rate YR is the rotational angular velocity about the vertical axis that passes through the center of gravity of the vehicle. For this reason, the yaw rate YR is basically larger when traveling on a curved road on which the vehicle makes a turning motion than on a straight road on which the vehicle does not make a turning motion. It becomes. Therefore, based on the yaw rate YR, it can be determined whether the vehicle is traveling on the curved first slope 91a or the straight second slope 91b. The threshold value YR _th is, for example, a value smaller than the yaw rate YR when the vehicle is traveling on the curved first slope 91a, and the vehicle is traveling on the linear second slope 91b. It is set to a value larger than the current yaw rate YR.

<Operation of correction processing unit>
Next, the operation of the correction processing unit 85 according to the shape of the road will be described. Here, the case where the vehicle travels on a flat road, the first slope 91a, and the second slope 91b will be described in order.

<When the vehicle travels on a flat road>
When the vehicle travels on a flat road having no crossing gradient, the gravity component Ga due to the road surface gradient is “0 (zero)”. Therefore, the value of the correction amount θ _c ^* calculated by the correction amount calculation unit 103 is “0”. That is, the target pinion angle θ _p ^* before correction becomes the final target pinion angle θ _p ^* that is used for the calculation of the ideal axial force F1 as it is. In this case, the relationship between the target pinion angle θ _p ^* and the ideal axial force F < _b ^> 1 is the same as when the configuration without the correction processing unit 85 is adopted as the vehicle model 72. Specifically, it is as follows.

As indicated by a solid line in the graph of FIG. 9A, when the vehicle travels on a flat road, the relationship between the target pinion angle θ _p ^* and the ideal axial force F1 is represented by a characteristic line L0.
The characteristic line L0 is a straight line passing through the origin. That is, when the vehicle travels on a flat road, when the target pinion angle θ _p ^* before correction is 0 degrees (neutral angle) corresponding to the steering neutral position when the vehicle goes straight, the ideal axial force F1 is also “0”. It becomes. As the target pinion angle θ _p ^* increases in the positive direction with 0 degree as a reference, the ideal axial force F1 increases linearly in the positive direction. As the target pinion angle θ _p ^* increases in the negative direction with 0 degree as a reference, the ideal axial force F1 increases linearly in the negative direction. The positive target pinion angle θ _p ^* corresponds to the right turning direction, and the negative target pinion angle θ _p ^* corresponds to the left turning direction.

As shown by the solid line in the graph of FIG. 9B, when the vehicle travels on a flat road, the relationship between the steering angle θ _s and the steering torque T _h (input torque T _in ^* ) is represented by a characteristic line L10. .
That is, when the steering torque _Th is “0”, the target steering reaction force T ₁ ^* , and hence the input torque T _in ^* becomes “0”, so that the target rudder angle θ _* and thus the target pinion angle θ _p ^*. Becomes “0”. Therefore, through the actual steering angle theta _s steering angle theta _s feedback control to follow the target steering angle theta _* a steering angle theta _s is 0 degree corresponding to the steering neutral position when the vehicle straight ahead. Further, the actual through feedback control of the pinion angle theta _p to the pinion angle theta _p follow the target pinion angle theta _p ^*, steered angle theta _w of the steered wheels 16 is zero degrees which corresponds to the steering neutral position when the vehicle is straight It becomes. Incidentally, the positive target rudder angle θ _* (steering angle θ _s ) corresponds to the right steering direction, and the negative target rudder angle θ _* (steering angle θ _s ) corresponds to the left steering direction.

<When the vehicle travels on the first ramp>
Next, a case where the vehicle travels on the curved first slope 91a will be described. Here, as shown in FIG. 5A, the first ramp 91a curves to the left with respect to the traveling direction of the vehicle, and from the outside of the curve in the direction along the transverse gradient. It inclines so that it becomes gradually lower toward the inside.

In this case, the positive correction amount θ _c ^* corresponding to the gravity component Ga is calculated according to the first map M1. By adding this correction amount θ _c ^* to the target pinion angle θ _p ^* before correction, the final target pinion angle θ _p ^* used for calculating the ideal axial force F1 is calculated. Therefore, the final target pinion angle θ _p ^* used for calculating the ideal axial force F1 is increased by the correction amount θ _c ^* from the target pinion angle θ _p ^* before correction.

As indicated by the alternate long and short dash line in the graph of FIG. 9A, when the vehicle travels on the first slope 91a of the left curve, the relationship between the target pinion angle θ _p ^* and the ideal axial force F1 is the characteristic line L1. expressed.
The characteristic line L1 can be regarded as the previous characteristic line L0 offset (translated) in the positive direction by the correction amount θ _c ^* along the horizontal axis. That is, when the vehicle travels on the first slope 91a having a left curve, the value of the target pinion angle θ _p ^{* at which} the ideal axial force F1 is “0” (hereinafter referred to as “zero point of the ideal axial force F1”). ) Is an angle “+ θ _c ^* ” offset in the positive direction by the correction amount θ _c ^* with respect to the zero point of the ideal axial force F1 when the vehicle travels on a flat road. Therefore, when the vehicle travels on the first slope 91a having the left curve, when the target pinion angle θ _p ^* is “0”, the ideal axial force F1 is not “0” but the ideal axial force “−F _y ”. It becomes.

When the vehicle travels on the first slope 91a having a left curve, the ideal axial force F1 is calculated by the correction amount θ _c ^* calculated according to the gravity component Ga according to the first map M1. The value of the final target pinion angle θ _p ^* is increased. For this reason, the final axial force F _sp calculated by the axial force distribution calculating unit 83 and, consequently, the value of the spring component T _sp ^* calculated by the converting unit 84 also increases in accordance with the increase amount of the target pinion angle θ _p ^*. To do. As a result, the value of the final input torque T _in ^* calculated by the subtractor 74 (see FIG. 3) decreases according to the increase amount of the spring component T _sp ^* , and the input torque T _in ^* decreases. Accordingly, the target rudder angle θ ^* decreases. Thus, the actual steering angle theta _s steering angle theta _s realized through the steering angle theta _s feedback control to follow the target steering angle theta ^* a is reduced according to the decrease amount of the target steering angle theta ^*.

As shown by a one-dot chain line in FIG. 9B, when the vehicle travels on the first slope 91a of the left curve, the relationship between the steering angle θ _s and the steering torque T _h (input torque T _in ^* ) is a characteristic. It is represented by a line L11.

The characteristic line L11 is assumed to be offset (translated) in the negative direction by an amount corresponding to the decrease amount of the target steering angle θ ^* based on the correction amount θ _c ^* along the horizontal axis with respect to the characteristic line L11. be able to. That is, when the vehicle travels through the first ramp 91a of the left curve, the value of the steering angle theta _s the steering torque T _h becomes "0" (hereinafter, referred to as "zero point of the steering torque T _h".) The , the vehicle is relative to the zero point, toward the negative direction by an amount corresponding to the decrease amount of the target steering angle theta ^* offset of the steering torque T _h in the case of traveling on a flat road.

Therefore, as shown by the characteristic line L11 in FIG. 9 (b), when the steering torque T _h is "0", the actual steering angle theta _s realized through feedback control of the steering angle theta _s, the vehicle The negative angle “−θ corresponding to the amount of decrease in the target steering angle θ ^* with reference to the steering angle θ _s (= 0 °) when the steering torque _Th is“ 0 ”when traveling on a flat road. _x ". This angle “−θ _x ” is a value corresponding to the ideal axial force “−F _y ” that is the value of the ideal axial force F1 when the target pinion angle θ _p ^* is “0”. This is because when the steering torque T _h (input torque T _in ^* ) is “0”, the target steering angle θ ^* corresponding to the spring component T _sp ^* based on the ideal axial force “−F _y ” is calculated. based on.

Incidentally, the positive steering angle θ _s corresponds to the right steering direction, and the negative steering angle θ _s corresponds to the left steering direction. Further, the value of the angle “−θ _x ” changes according to the gravity component Ga due to the road surface gradient. This is because the value of the correction amount θ _c ^* changes depending on the value of the gravity component Ga due to the road gradient, and the offset amount of the characteristic line L11 with respect to the characteristic line L10 also changes depending on the value of the correction amount θ _c ^* . Also, the positive gravity component G _a corresponds to the first ramp 91a of the left curve having a transverse gradient which is inclined so as to gradually increase toward the right direction with respect to the traveling direction of the vehicle. Negative gravity component G _a corresponds to the first ramp 91a of the right curve having a transverse gradient which is inclined so as to gradually increase toward the left direction with respect to the traveling direction of the vehicle.

Therefore, when the vehicle is traveling on the first slope 91a of the left curve, the steering wheel 11 is steered with reference to the steering neutral position even when the steering torque _Th is not applied to the steering wheel 11. The angle θ _s (= −θ _x ) is held at a position rotated in the left steering direction. The steered wheels 16, based on the its steering neutral position, the angle left steering direction by the steering angle theta _w corresponding to the target pinion angle theta _p ^* based on the "- [theta] _x" target steering angle corresponding to theta ^* It is held at the position steered toward. Here, since the first slope 91a of the left curve is curved to the left with respect to the traveling direction of the vehicle, the left steering direction of the steering wheel 11 and the left steering direction of the steered wheels 16 are the left curve. This corresponds to the direction in which the road surface gradient of the first slope 91a decreases. For this reason, as indicated by the solid arrow C1 in FIG. 5A, the vehicle 90 can curve the route 92 on the first slope 91a of the left curve without the driver operating the steering wheel 11. Drive along.

  Next, a case where the vehicle travels on the first slope 91a whose road surface slope direction is opposite to that of the first slope 91a having the left curve shown in FIG. 5A will be described. Here, the first slope 91a curves to the right with respect to the traveling direction of the vehicle, and inclines so as to gradually decrease from the outside to the inside of the curve in the direction along the transverse gradient. ing. The gravity component Ga when the vehicle is traveling on the first curved road 91a with the right curve is the gravity when the vehicle is traveling on the first curved path 91a with the left curve shown in FIG. The sign of the sign is reversed with respect to the component Ga.

In this case, the negative correction amount θ _c ^* (= − | + θ _c ^* |) corresponding to the negative gravity component Ga is calculated according to the first map M1 shown in FIG. For this reason, when the vehicle travels on the first slope 91a having the right curve, a characteristic line (not shown) indicating the relationship between the target pinion angle θ _p ^* and the ideal axial force F1 is shown in FIG. The characteristic line L0 is offset along the horizontal axis in the negative direction (in the opposite direction to the characteristic line L1 shown in FIG. 9A) by the absolute value of the correction amount θ _c ^* . Therefore, when the vehicle travels on the first slope 91a of the right curve, when the target pinion angle θ _p ^* is “0”, the ideal axial force F1 is not “0” but a positive value (= | −F _y │).

When the vehicle travels on the first slope 91a having a right curve, the final target pinion angle used for calculating the ideal axial force F1 is calculated by the correction amount θ _c ^* calculated according to the gravity component Ga. The value of θ _p ^* is decreased. For this reason, the final axial force F _sp calculated by the axial force distribution calculating unit 83 and, in turn, the value of the spring component T _sp ^* calculated by the converting unit 84 also decreases in accordance with the amount of decrease in the target pinion angle θ _p ^*. To do. As a result, the value of the final input torque T _in ^* calculated by the subtractor 74 (see FIG. 3) increases according to the decrease amount of the spring component T _sp ^* , and increases the input torque T _in ^* . Accordingly, the target rudder angle θ ^* increases. Thus, the actual steering angle theta _s steering angle theta _s realized through the steering angle theta _s feedback control to follow the target steering angle theta ^* a increases with the increase of the target steering angle theta ^*.

When the vehicle travels on the first slope 91a having a right curve, a characteristic line (not shown) indicating the relationship between the steering angle θ _s and the steering torque T _h (input torque T _in ^* ) is shown in FIG. The characteristic line L10 shown in FIG. 9 is in the positive direction (in the opposite direction to the characteristic line L11 shown in FIG. 9B) by an amount corresponding to the increase amount of the target rudder angle θ ^* based on the correction amount θ _c ^* along the horizontal axis. ) To be offset. That is, when the vehicle travels through the first ramp 91a of the right curve, the value of the steering angle theta _s the steering torque T _h becomes "0" (hereinafter, referred to as "zero point of the steering torque T _h".) The , the vehicle is relative to the zero point, toward the amount corresponding positive direction corresponding to the increase amount of the target steering angle theta ^* offset of the steering torque T _h in the case of traveling on a flat road. Therefore, when the steering torque T _h is "0", the actual steering angle theta _s realized through feedback control of the steering angle theta _s is the steering torque T _h is "0 when the vehicle is traveling on a flat road Is a positive angle (= | −θ _x |) corresponding to the increase amount of the target rudder angle θ ^* with reference to the rudder angle θ _s (= 0 °).

Therefore, when the vehicle is traveling on the first slope 91a of the right curve, the steering wheel 11 is correctly set with reference to the steering neutral position even when the steering torque _Th is not applied to the steering wheel 11. The steering angle θ _s (= | −θ _x |) is maintained at a position rotated in the right steering direction. Further, the steered wheel 16 has a steered angle θ _w corresponding to a target pinion angle θ _p ^* based on a target steered angle θ ^* corresponding to a positive angle (= | −θ _x |) with reference to the neutral position of the steered wheel. It is held at the position steered only in the right steered direction. Here, since the vehicle is traveling on the first slope 91a having the right curve, the right steering direction of the steering wheel 11 and the right steering direction of the steered wheels 16 are the same as those on the first slope 91a having the right curve. This corresponds to the direction in which the road surface slope decreases. For this reason, even if the driver does not operate the steering wheel 11, the vehicle 90 travels along the curve of the route 92 in the first slope 91a of the right curve.

<When the vehicle travels on the second ramp>
Next, a case where the vehicle travels on the straight second slope 91b will be described. Here, as shown in FIG. 5B, the road surface of the second inclined road 91b is inclined so as to gradually become lower from the right side to the left side with respect to the traveling direction of the vehicle (left Slope).

In this case, negative correction amount corresponding to the gravity component G _a θ _c ^* is calculated in accordance with the second map M2. By adding this correction amount θ _c ^* to the target pinion angle θ _p ^* before correction, the final target pinion angle θ _p ^* used for calculating the ideal axial force F1 is calculated. Therefore, the final target pinion angle θ _p ^* used for calculating the ideal axial force F1 is reduced by the correction amount θ _c ^* from the value of the target pinion angle θ _p ^* before correction.

As indicated by a two-dot chain line in the graph of FIG. 9A, when the vehicle travels on the second inclined road 91b inclined to the left, the relationship between the target pinion angle θ _p ^* and the ideal axial force F1 is the characteristic line L2. It is represented by
The characteristic line L2 can be regarded as the previous characteristic line L0 offset (translated) in the negative direction along the horizontal axis by the correction amount θ _c ^* . That is, when the vehicle travels on the second sloping road 91b inclined to the left, the zero point of the ideal axial force F1 is the zero point (θ _p ^* = 0) of the ideal axial force F1 when the vehicle travels on a flat road. On the other hand, the angle is “−θ _c ^* ” offset in the negative direction by the absolute value of the correction amount θ _c ^* . Therefore, when the vehicle travels on the second inclined road 91b inclined to the left, when the target pinion angle θ _p ^* is “0”, the ideal axial force F1 is not “0” but the ideal axial force “+ F _y ”. Become.

If the vehicle travels a second ramp 91b of the left slope, only negative correction amount theta _c ^* of minutes is calculated in accordance with the gravity component G _a in accordance with the second map M2, the calculation of the ideal axial force F1 The final target pinion angle θ _p ^* value used is reduced. For this reason, the final axial force F _sp calculated by the axial force distribution calculating unit 83 and, in turn, the value of the spring component T _sp ^* calculated by the converting unit 84 also decreases in accordance with the amount of decrease in the target pinion angle θ _p ^*. To do. As a result, the value of the final input torque T _in ^* calculated by the subtractor 74 (see FIG. 3) increases according to the decrease amount of the spring component T _sp ^* , and increases the input torque T _in ^* . Accordingly, the target rudder angle θ ^* increases. Thus, the actual steering angle theta _s steering angle theta _s realized through the steering angle theta _s feedback control to follow the target steering angle theta ^* a increases with the increase of the target steering angle theta ^*.

As shown by a two-dot chain line in FIG. 9B, when the vehicle travels on the second inclined road 91b inclined to the left, the relationship between the steering angle θ _s and the steering torque T _h (input torque T _in ^* ) is It is represented by a characteristic line L12.

The characteristic line L12 is assumed to be offset (translated) in the positive direction by an amount corresponding to the increase amount of the target rudder angle θ ^* based on the correction amount θ _c ^* along the horizontal axis with respect to the characteristic line L12. be able to. That is, when the vehicle travels through the second ramp 91b of the left slope, the value of the steering angle theta _s the steering torque T _h becomes "0" (hereinafter, referred to as "zero point of the steering torque T _h".) The , the vehicle is relative to the zero point, toward the amount corresponding positive direction corresponding to the increase amount of the target steering angle theta ^* offset of the steering torque T _h in the case of traveling on a flat road.

Therefore, as shown by the characteristic line L12 in FIG. 9 (b), when the steering torque T _h is "0", the actual steering angle theta _s realized through feedback control of the steering angle theta _s, the vehicle Is a positive angle “+ θ _x corresponding to the amount of increase in the target steering angle θ ^* with reference to the steering angle θ _s (= 0 °) when the steering torque _Th is“ 0 ”when traveling on a flat road. " This angle “+ θ _x ” is a value corresponding to the ideal axial force “+ F _y ” that is the value of the ideal axial force F1 when the target pinion angle θ _p ^* is “0”. This is because when the steering torque T _h (input torque T _in ^* ) is “0”, the target steering angle θ ^* corresponding to the spring component T _sp ^* based on the ideal axial force “+ F _y ” is calculated. Based.

Therefore, when the vehicle is traveling on the second inclined road 91b inclined to the left, the steering wheel 11 is steered with reference to the steering neutral position even when the steering torque _Th is not applied to the steering wheel 11. The angle θ _s (= + θ _x ) is held at a position rotated in the right steering direction. The steered wheels 16, based on the its steering neutral position, the angle "+ theta _x" to the right by steering direction steering angle theta _w corresponding to the target pinion angle theta _p ^* based on the target steering angle theta _* corresponding The position steered toward is held. Here, the right steering direction of the steering wheel 11 and the right steering direction of the steered wheels 16 correspond to the direction in which the road gradient in the second inclined road 91b that is inclined to the left increases. For this reason, as indicated by the solid line arrow C2 in FIG. 5B, the vehicle 90 moves down the road surface of the second inclined road 91b that is inclined to the left even if the driver does not operate the steering wheel 11. Go straight along line 92 without turning naturally toward

  Next, a case will be described in which the vehicle travels on the second slope 91b whose road surface slope direction is opposite to that of the second slope 91b having the left slope shown in FIG. 5B. Here, the road surface of the second inclined road 91b is inclined so as to gradually become lower from the left side to the right side with respect to the traveling direction of the vehicle (right inclination). The gravity component Ga when the vehicle is traveling on the second slope 91b having the right slope is the same as that when the vehicle is traveling on the second slope 91b having the left slope shown in FIG. 5B. The sign of the sign is reversed with respect to the gravity component Ga.

In this case, a positive correction amount corresponding to the gravity component G _a θ _c ^* is calculated in accordance with the second map M2 shown in Figure 8 (b). For this reason, when the vehicle travels on the second inclined road 91b inclined rightward, a characteristic line (not shown) indicating the relationship between the target pinion angle θ _p ^* and the ideal axial force F1 is shown in FIG. The characteristic line L0 is offset along the horizontal axis in the positive direction (the direction opposite to the characteristic line L2 shown in FIG. 9A) by the absolute value of the correction amount θ _c ^* . Therefore, when the vehicle travels on the second inclined road 91b inclined rightward, when the target pinion angle θ _p ^* is “0”, the ideal axial force F1 is not “0” but a negative value (= − | + F _y │).

If the vehicle travels a second ramp 91b of the right slope, only positive correction amount theta _c ^* of minutes is calculated in accordance with the gravity component G _a, final used for calculation of the ideal axial force F1 The value of the target pinion angle θ _p ^* is increased. For this reason, the final axial force F _sp calculated by the axial force distribution calculating unit 83 and, in turn, the value of the spring component T _sp ^* calculated by the converting unit 84 also increases according to the increase amount of the target pinion angle θ _p ^*. To do. As a result, the value of the final input torque T _in ^* calculated by the subtractor 74 (see FIG. 3) decreases according to the increase amount of the spring component T _sp ^* , and the input torque T _in ^* decreases. Accordingly, the target rudder angle θ ^* decreases. Thus, the actual steering angle theta _s steering angle theta _s realized through the steering angle theta _s feedback control to follow the target steering angle theta ^* a is reduced according to the decrease amount of the target steering angle theta ^*.

When the vehicle travels on the second inclined road 91b inclined rightward, a characteristic line (not shown) indicating the relationship between the steering angle θ _s and the steering torque T _h (input torque T _in ^* ) is shown in FIG. Is offset in the negative direction (opposite to the characteristic line L12) by an amount corresponding to the amount of decrease in the target steering angle θ ^* based on the correction amount θ _c ^* along the horizontal axis. . That is, when the vehicle travels through the second ramp 91b of the right slope, the value of the steering angle theta _s the steering torque T _h becomes "0" (hereinafter, referred to as "zero point of the steering torque T _h".) The , the vehicle is relative to the zero point, toward the negative direction by an amount corresponding to the decrease amount of the target steering angle theta ^* offset of the steering torque T _h in the case of traveling on a flat road. Therefore, when the steering torque T _h is "0", the actual steering angle theta _s realized through feedback control of the steering angle theta _s is the steering torque T _h is "0 when the vehicle is traveling on a flat road as the steering angle theta _s reference ₍₌ 0 °) when "a, a negative angle corresponding to the decrease amount of the target steering angle _{^{θ * (= -│ + θ x}} │).

Therefore, when the vehicle is traveling on the second inclined road 91b that is inclined to the right, the steering wheel 11 is steered based on the steering neutral position even when the steering torque _Th is not applied to the steering wheel 11. The angle θ _s (= − | + θ _x |) is held at a position rotated toward the left steering direction. The steered wheels 16, based on the its steering neutral position, a negative angle (= -│ + θ _x │) target pinion angle based on the target steering angle theta _* corresponding to theta _p ^* steered angle theta _w corresponding to It is held at the position steered toward the left steered direction only. Here, the left steering direction of the steering wheel 11 and the left steering direction of the steered wheels 16 correspond to the direction in which the road gradient in the second inclined road 91b with the right inclination increases. For this reason, even if the driver does not operate the steering wheel 11, the vehicle 90 goes straight along the route 92 without naturally turning toward the direction of going down the road surface of the right-sloped second slope 91b. .

<Effect of the first embodiment>
Therefore, according to the first embodiment, the following effects can be obtained.
(1) When the vehicle is traveling on the curved first slope 91a, the control device 50 executes the first control corresponding to the first slope 91a. That is, the final target pinion angle θ _p ^* (absolute value) used for calculating the ideal axial force F1 is increased by the correction amount θ _c ^* through the correction processing unit 85. As a result, the steering angle θ _s (target steering angle θ ^* ) when the steering torque _Th is “0” is the first relative to the neutral angle “0 degree” corresponding to the steering neutral position of the steering wheel 11. This is offset by an angle corresponding to the target steering angle θ ^* based on the correction amount θ _c ^* toward the direction in which the road surface of the inclined road 91a is lowered. Further, the target pinion angle θ _p ^* based on the target steering angle θ ^* corresponding to the correction amount θ _c ^* is also set based on the neutral angle “0 degree” corresponding to the steering neutral position of the steered wheels 16 as the first. It is offset by an angle corresponding to the target rudder angle θ ^* based on the correction amount θ _c ^* toward the direction in which the road surface of the inclined road 91a is lowered. Therefore, when the vehicle travels a first ramp 91a, even when no steering torque T _h is applied to the steering wheel 11, steering angle theta _s and the steering corresponding to the inclination of the first ramp 91a by angle theta _w is achieved, the vehicle travels while turning along the lines 92 of the first ramp 91a. Therefore, when the vehicle travels on the first slope 91a, an appropriate steering feeling is realized.

(2) When the vehicle is traveling on the linear second slope 91b, the control device 50 executes the second control corresponding to the second slope 91b. That is, the final target pinion angle θ _p ^* (absolute value) used for calculating the ideal axial force F1 is reduced by the correction amount θ _c ^* through the correction processing unit 85. As a result, the steering angle θ _s (target steering angle θ ^* ) when the steering torque _Th is “0” is set to the second value based on the neutral angle “0 degree” corresponding to the steering neutral position of the steering wheel 11. This is offset by an angle corresponding to the target rudder angle θ ^* based on the correction amount θ _c ^* toward the direction in which the road surface of the inclined road 91b rises. Further, the target pinion angle θ _p ^* based on the target rudder angle θ ^* corresponding to the correction amount θ _c ^* is also determined based on the neutral angle “0 degree” corresponding to the steered neutral position of the steered wheels 16 as the second. It is offset by an angle corresponding to the target rudder angle θ ^* based on the correction amount θ _c ^* toward the direction in which the road surface of the inclined road 91b rises. Therefore, when the vehicle travels through the second ramp 91b, even when no steering torque T _h is applied to the steering wheel 11, steering angle theta _s and the steering corresponding to the inclination of the second ramp 91b by angle theta _w is achieved, the vehicle moves straight along the route 92 of the second ramp 91b. Therefore, even when the vehicle travels on the second slope 91b, an appropriate steering feeling is realized.

(3) The first ramp 91a is a road extending in a curved line, and the second ramp 91b is a road extending in a straight line. For this reason, the yaw rate YR when the vehicle travels on the first ramp 91a is larger than the yaw rate YR when the vehicle travels on the second ramp 91b. By paying attention to the difference in the yaw rate YR, it can be determined whether the vehicle is traveling on the first ramp 91a or the second ramp 91b. Controller 50, when the yaw rate YR is the threshold value YR _th or executes the first control corresponding to the first ramp 91a, the second slope when the yaw rate YR is less than the threshold value YR _th The second control corresponding to the path 91b is executed.

(4) The steering torque is obtained by adding a correction amount θ _c ^* corresponding to the gravity component G _a in the direction along the road gradient to the target pinion angle θ _p ^* used for calculating the ideal axial force F1. The target rudder angle θ ^* when _Th is “0” can be changed by an angle corresponding to the correction amount θ _c ^* with reference to the neutral angle (0 degrees) corresponding to the steering neutral position. Accordingly, the target pinion angle θ _p ^* when the steering torque _Th is “0” is also an angle corresponding to the correction amount θ _c ^* on the basis of the neutral angle (0 degree) corresponding to the steering neutral position. Only changes. This is because the target pinion angle θ _p ^* is calculated based on the target steering angle θ ^* . Here, the units of the correction amount θ _c ^* and the target pinion angle θ _p ^* are the same. Therefore, the designer adjusts the relationship between the gravity component Ga and the correction amount θ _c ^* in the first map M1 and the second map M2 to thereby adjust the first ramp 91a and the second ramp 91b. The target rudder angle θ ^* corresponding to can be set easily and sensuously. Further, by adjusting the relationship between the gravity component Ga and the correction amount θ _c ^* in the first map M1 and the second map M2, when traveling on the first slope 91a and the second slope 91b, A desired steering feeling can be realized.

(5) generally a vehicle speed sensor 501 mounted on the vehicle, based on the detection result of the lateral acceleration sensor 502 and yaw rate sensor 503, can calculate the gravity component G _a in the direction along the road gradient. The gravity component G _a is larger inclination angle of the inclined path which the vehicle travels β becomes a larger value. Thus, without adding a new configuration to the vehicle, the vehicle based on the gravity component G _a it is possible to determine whether running any ramp and a flat road.

<Second Embodiment>
Next, a second embodiment of the steering control device will be described. This embodiment basically has the same configuration as that of the first embodiment shown in FIGS. This embodiment is different from the first embodiment in that a configuration for offset correction of the zero point of the ideal axial force F1 is provided in the ideal axial force calculation unit 81, not in the preceding stage of the ideal axial force calculation unit 81. ing.

As shown in FIG. 10, the ideal axial force calculation unit 81 includes an axial force calculation unit 112 and a correction processing unit 115.
The axial force calculation unit 112 calculates the ideal axial force F1 using a map that defines the relationship between the target pinion angle θ _p ^* and the ideal axial force F1 according to the vehicle speed V. The absolute value of the ideal axial force F1 is set to a larger value as the absolute value of the target pinion angle θ _p ^* increases. Incidentally, when the target pinion angle θ _p ^* is a positive value, the ideal axial force F1 is a positive value. When the target pinion angle θ _p ^* is a negative value, the ideal axial force F1 is a negative value.

The correction processing unit 115 calculates the final ideal axial force F1 by correcting the signed ideal axial force F1 calculated by the axial force calculation unit 112 according to the inclination of the slope.
As shown in FIG. 11, the correction processing unit 115 basically has the same configuration (101 to 106) as the correction processing unit 85 of the first embodiment shown in FIG. The correction processing unit 115 is different from the correction processing unit 85 in the following points.

The correction amount calculation unit 103 uses the third map M3 and the fourth map M4 to calculate a correction amount F _c (correction axial force) corresponding to the gravity component G _a . This correction amount F _c is for the ideal axial force F 1 with a sign calculated by the axial force calculation unit 112. As shown in parentheses in FIGS. 8A and 8B, the third map M3 and the fourth map M4 are maps in which the horizontal axis is the gravity component G _a and the vertical axis is the correction amount F _c. In this case, the relationship between the gravity component G _a and the correction amount F _c is defined. The third map M3 has characteristics similar to those of the first map M1 shown in FIG. 8A (change tendency of the correction amount F _c with respect to the gravity component G _a ). The fourth map M4 has the same characteristics as the second map M2 shown in FIG.

The multiplier 105 multiplies the correction amount F _c calculated by the correction amount calculation unit 103 and the gain G _c calculated by the gain calculation unit 104 to calculate the final correction amount F _c .

The adder 106 adds a correction processing for signed ideal axial force F1, which is calculated by the axial force operating section 112, and the ideal axial force F1, and a final correction amount F _c which is calculated by the multiplier 105 By doing so, the final ideal axial force F1 is calculated.

Next, the operation of the correction processing unit 115 will be described.
When the vehicle travels on the first slope 91a having the left curve shown in FIG. 5A, the value of the target pinion angle θ _p ^* used for calculating the ideal axial force F1 is increased. In the same manner as the above, the final axial force F _sp calculated by the axial force distribution calculating unit 83 and, in turn, the value of the spring component T _sp ^* calculated by the converting unit 84 increases according to the correction amount F _c . As a result, the value of the final input torque T _in ^* calculated by the subtractor 74 (see FIG. 3) decreases according to the increase amount of the spring component T _sp ^* , and the input torque T _in ^* decreases. Accordingly, the target rudder angle θ ^* decreases. Thus, the actual steering angle theta _s steering angle theta _s realized through the steering angle theta _s feedback control to follow the target steering angle theta ^* a is reduced according to the decrease amount of the target steering angle theta ^*. As a result, when the vehicle travels on the first slope 91a, the relationship between the steering angle θ _s and the steering torque T _h (input torque T _in ^* ) is shown in FIG. The characteristic indicated by the line L11 is obtained.

When the vehicle travels on the first slope 91a having a right curve, the axial force is reduced in the same manner as in the first embodiment in which the value of the target pinion angle θ _p ^* used for calculating the ideal axial force F1 is reduced. The final axial force F _sp calculated by the distribution calculation unit 83 and, in turn, the value of the spring component T _sp ^* calculated by the conversion unit 84 decreases according to the correction amount F _c . As a result, the value of the final input torque T _in ^* calculated by the subtractor 74 (see FIG. 3) increases according to the decrease amount of the spring component T _sp ^* , and increases the input torque T _in ^* . Accordingly, the target rudder angle θ ^* increases. Thus, the actual steering angle theta _s steering angle theta _s realized through the steering angle theta _s feedback control to follow the target steering angle theta ^* a increases with the increase of the target steering angle theta ^*. As a result, when the vehicle travels on the first slope 91a having a right curve, the relationship between the steering angle θ _s and the steering torque T _h (input torque T _in ^* ) is a characteristic shown in FIG. 9B. A characteristic line (not shown) obtained by offsetting the line L10 along the horizontal axis in the positive direction (opposite to the characteristic line L11) by an amount corresponding to the increase amount of the target steering angle θ ^* based on the correction amount θ _c ^*. The characteristics shown are obtained.

When the vehicle travels on the second slope 91b having the left slope shown in FIG. 5B, the value of the target pinion angle θ _p ^* used for calculating the ideal axial force F1 is reduced. In the same manner as the above, the final axial force F _sp calculated by the axial force distribution calculating unit 83, and consequently the value of the spring component T _sp ^* calculated by the converting unit 84 decreases according to the correction amount F _c . As a result, the value of the final input torque T _in ^* calculated by the subtractor 74 (see FIG. 3) increases according to the decrease amount of the spring component T _sp ^* , and increases the input torque T _in ^* . Accordingly, the target rudder angle θ ^* increases. Thus, the actual steering angle theta _s steering angle theta _s realized through the steering angle theta _s feedback control to follow the target steering angle theta ^* a increases with the increase of the target steering angle theta ^*. Thus, when the vehicle travels on the second slope 91b, the relationship between the steering angle θ _s and the steering torque T _h (input torque T _in ^* ) is indicated by the two-dot chain line in FIG. The characteristic indicated by the characteristic line L12 is obtained.

When the vehicle travels on the second inclined road 91b that is inclined to the right, the axial force is increased similarly to the first embodiment in which the value of the target pinion angle θ _p ^* used for the calculation of the ideal axial force F1 is increased. The final axial force F _sp calculated by the distribution calculation unit 83 and, in turn, the value of the spring component T _sp ^* calculated by the conversion unit 84 increases in accordance with the correction amount F _c . As a result, the value of the final input torque T _in ^* calculated by the subtractor 74 (see FIG. 3) decreases according to the increase amount of the spring component T _sp ^* , and the input torque T _in ^* decreases. Accordingly, the target rudder angle θ ^* decreases. Thus, the actual steering angle theta _s steering angle theta _s realized through the steering angle theta _s feedback control to follow the target steering angle theta ^* a is reduced according to the decrease amount of the target steering angle theta ^*. As a result, when the vehicle travels on the second inclined road 91b that is inclined to the right, the relationship between the steering angle θ _s and the steering torque T _h (input torque T _in ^* ) is a characteristic shown in FIG. 9B. A characteristic line (not shown) obtained by offsetting the line L10 along the horizontal axis in the negative direction (opposite to the characteristic line L12) by an amount corresponding to the reduction amount of the target steering angle θ ^* based on the correction amount θ _c ^*. The characteristics shown are obtained.

Thus, the steering torque T _h (input torque T _in ^* ) is “0” by adding the correction amount F _c to the signed ideal axial force F 1 calculated by the axial force calculator 112. The target rudder angle θ _{* at} that time can be changed by an angle corresponding to the correction amount F _c with reference to the steering neutral position (= 0 degree). Accordingly, the target pinion angle θ _p ^* can also be changed by an angle corresponding to the correction amount F _c with reference to the steering neutral position (= 0 degree). Therefore, the steering angle θ _s and the steering angle θ _w suitable for the inclination of the first inclined path 91a and the second inclined path 91b can be realized.

Therefore, according to the second embodiment, the same effects as (1) to (5) of the first embodiment can be obtained.
<Third Embodiment>
Next, a third embodiment of the steering control device will be described. The axial force distribution calculation unit 83 shown in FIG. 4 may be embodied as follows. This embodiment can be applied to both the first embodiment and the second embodiment.

  As illustrated in FIG. 12, the axial force distribution calculation unit 83 includes a multiplier 121, a subtracter 122, a distribution ratio calculation unit 123, a multiplier 124, a subtractor 125, a multiplier 126, and an adder 127. .

  The multiplier 121 calculates the centrifugal acceleration α by multiplying the yaw rate YR detected by the yaw rate sensor 503 and the vehicle speed V detected by the vehicle speed sensor 501.

Subtractor 122, from the lateral acceleration LA detected through the lateral acceleration sensor 502, by subtracting the centrifugal acceleration α which is calculated by the multiplier 101 calculates the gravity component G _a in the direction along the road gradient.

The distribution ratio calculation unit 123 calculates the distribution ratio D1 in accordance with the gravity component G _a is computed by a subtracter 122. The distribution ratio D1 is a value in the range from “0” to “1”. Distribution ratio D1 until the absolute value of the gravity component G _a reaches the set value G _th is a constant value regardless of the absolute value of the gravity component G _a (in this case, "1") is maintained. Distribution ratio D1 is after the absolute value of the gravity component G _a has reached the set value G _th, with an increase in the absolute value of the gravity component G _a, gradually decreases toward "0".

The multiplier 124 multiplies the corrected ideal axial force F1 calculated by the ideal axial force calculation unit 81 by the distribution ratio D1 calculated by the distribution ratio calculation unit 123, thereby obtaining the ideal axial force F1 after distribution. _a is calculated. Here, the corrected ideal axial force F1 is the ideal axial force F1 calculated based on the target pinion angle θ _p ^* to which the correction amount θ _c ^* in the first embodiment is added, or the second embodiment. The ideal axial force F1 to which the correction amount _Fc is added.

  The subtractor 125 calculates the distribution ratio D2 by subtracting the distribution ratio D1 calculated by the distribution ratio calculation unit 123 from “1” that is a fixed value stored in the storage device of the control device 50.

Multiplier 126, the estimated axial force F2, which is calculated by the estimation axial force calculating unit 82, by multiplying the distribution ratio D2 is computed by a subtracter 125 calculates the estimated axial force F2 _a after allocation.

The adder 127 adds the ideal axial force F1 _a after distribution calculated by the multiplier 124 and the estimated axial force F2 _a after distribution calculated by the multiplier 126 to thereby add the spring component T _sp ^* . The final axial force _{Fsp used} for the calculation is calculated.

<Operation and Effect of Third Embodiment>
Therefore, according to the third embodiment, the following operations and effects can be obtained.
(6) as the absolute value of the gravity component G _a is increased, while the distribution ratio D1 is decreased from the ideal axial force F1 of the corrected distribution ratio D2 for estimating the axial force F2 increases. That is, as the absolute value of the gravity component G _a is increased, the proportion of the estimated axial force F2 occupied in the final axial force F _sp increases. For estimating the axial force F2 is to actual road surface reaction force acting on the steered wheels 16, 16 (axial force) is calculated on the basis of the current value I _b of the steering motor 41 to be reflected, estimated axial force F2 The actual road reaction force is also reflected. Therefore, as the absolute value of the gravity component G _a is increased, i.e., the road surface gradient of the first ramp 91a or the second ramp 91b (degree of inclination) becomes larger, the final axial force F _sp, thus the final The degree to which the actual road surface reaction force is reflected on the actual input torque T _in ^* is increased. Thereby, the target rudder angle θ ^* and the target pinion angle θ _p ^* corresponding to the inclination degree (actual road reaction force) of the first inclined path 91a or the second inclined path 91b are calculated. Therefore, the driver can steer more naturally. Further, an appropriate steering feeling corresponding to the inclination of the first inclined path 91a or the second inclined path 91b is realized.

<Fourth embodiment>
Next, a fourth embodiment of the steering control device will be described. This embodiment is different from the third embodiment in the point of the calculation method of the axial force distribution calculation unit 83.

As illustrated in FIG. 13, the axial force distribution calculation unit 83 includes a subtractor 131, a distribution ratio calculation unit 132, a multiplier 133, a subtracter 134, a multiplier 135, and an adder 136.
The subtractor 131 calculates the axial force deviation ΔF by subtracting the estimated axial force F2 calculated by the estimated axial force calculation unit 82 from the ideal axial force F1 before correction calculated by the ideal axial force calculation unit 81. To do. Here, the ideal axial force F1 before correction is the ideal axial force F1 calculated based on the target pinion angle θ _p ^* before the correction amount θ _c ^* in the first embodiment is added, or the second axial force F1. refers to the ideal axial force F1 prior to the correction amount F _c in the embodiment of is added.

The distribution ratio calculation unit 132 calculates the distribution ratio D3 according to the absolute value of the axial force deviation ΔF calculated by the subtracter 131. The distribution ratio D3 is a value in the range from “0” to “1”. Distribution ratio D3 is until the absolute value of the axial force difference [Delta] F reaches the set value [Delta] F _th, a constant value regardless of the absolute value of the axial force difference [Delta] F (here, "1") is maintained. Distribution ratio D3 is after the absolute value of the axial force difference [Delta] F has reached the set value [Delta] F _th, gradually decreases toward "0" with an increase in the absolute value of the axial force deviation [Delta] F.

Incidentally, the distribution ratio calculation unit 132 sets the axial force deviation ΔF on the condition that the target rudder angle θ _* is smaller than the rudder angle threshold after the absolute value of the axial force deviation ΔF reaches the set value ΔF _th . The distribution ratio D3 may be gradually decreased toward “0” as the absolute value increases. This is because if the absolute value of the axial force deviation ΔF reaches the set value ΔF _th and the target rudder angle θ _* is smaller than the rudder angle threshold, the vehicle may be traveling on an inclined road. is there.

The multiplier 133 multiplies the corrected ideal axial force F1 calculated by the ideal axial force calculation unit 81 by the distribution ratio D3 calculated by the distribution ratio calculation unit 132, thereby providing the ideal axial force F1 _b after distribution. Is calculated.

  The subtractor 134 calculates the distribution ratio D4 by subtracting the distribution ratio D3 calculated by the distribution ratio calculation unit 132 from “1” that is a fixed value stored in the storage device of the control device 50.

Multiplier 135, the estimated axial force F2, which is calculated by the estimation axial force calculating unit 82, by multiplying the distribution ratio D4 which is computed by a subtracter 134 calculates the estimated axial force F2 _b after allocation.

The adder 136 adds the ideal axial force F1 _b after distribution calculated by the multiplier 133 and the estimated axial force F2 _b after distribution calculated by the multiplier 135 to thereby add the spring component T _sp ^* . The final axial force _{Fsp used} for the calculation is calculated.

<Operation and Effect of Fourth Embodiment>
Therefore, according to the fourth embodiment, the following actions and effects can be obtained.
(7) The ideal axial force F1 calculated based on the target pinion angle θ _p ^* is an axial force ignoring the balance of forces acting on the vehicle. In contrast, the current value I _b estimated axial force F2 which is calculated based on the steering motor 41 is axial force balance of forces acting on the vehicle is reflected. For this reason, the absolute value of the axial force deviation ΔF, which is the difference between the ideal axial force F1 and the estimated axial force F2, increases as the inclination angle β of the first inclined path 91a or the second inclined path 91b increases. Become. That is, the absolute value of the axial force deviation ΔF is a value that reflects the degree of inclination of the first inclined path 91a or the second inclined path 91b.

Assuming this, as the absolute value of the axial force deviation ΔF increases, the distribution ratio D3 to the ideal axial force F1 before correction decreases, while the distribution ratio D4 to the estimated axial force F2 increases. That is, as the absolute value of the axial force difference ΔF increases, the proportion of the estimated axial force F2 occupied in the final axial force F _sp increases. Therefore, as the absolute value of the axial force deviation ΔF increases, that is, as the road surface gradient (inclination degree) of the first inclined path 91a or the second inclined path 91b increases, the final axial force F _sp , and eventually the final The degree of reflecting the actual road surface reaction force (axial force) to the actual input torque T _in ^* increases. Thereby, the target rudder angle θ ^* and the target pinion angle θ _p ^* corresponding to the inclination degree (actual road reaction force) of the first inclined path 91a or the second inclined path 91b are calculated. Therefore, the driver can steer more naturally. Further, an appropriate steering feeling corresponding to the inclination of the first inclined path 91a or the second inclined path 91b is realized.

<Fifth embodiment>
Next, a fifth embodiment of the steering control device will be described. In the present embodiment, the third embodiment and the fourth embodiment are integrated as a calculation function of the axial force distribution calculation unit 83.

  As shown in FIG. 14, the axial force distribution calculation unit 83 includes a multiplier 121, a subtractor 122 and a distribution ratio calculation unit 123 in the third embodiment, and a subtractor 131 and a distribution ratio in the third embodiment. A calculation unit 132 is included. In addition, the axial force distribution calculation unit 83 includes a multiplier 141, a multiplier 142, a subtracter 143, a multiplier 144, and an adder 145.

Multiplier 141, a distribution ratio D1 corresponding to the absolute value of the gravity component G _a, which is calculated by the distribution ratio calculation unit 123, the distribution ratio corresponding to the absolute value of the axial force difference ΔF is calculated by the distribution ratio calculation unit 132 By multiplying by D3, a distribution ratio D5 to the corrected ideal axial force F1 is calculated.

The multiplier 142 multiplies the corrected ideal axial force F1 calculated by the ideal axial force calculation unit 81 by the distribution ratio D5 calculated by the multiplier 141, thereby obtaining the ideal axial force F1 _c after distribution. Calculate.

  The subtractor 143 calculates the distribution ratio D6 for the estimated axial force F2 by subtracting the distribution ratio D5 calculated by the multiplier 141 from “1” which is a fixed value stored in the storage device of the control device 50. To do.

Multiplier 144, the estimated axial force F2, which is calculated by the estimation axial force calculating unit 82, by multiplying the distribution ratio D6 which is computed by a subtracter 143 calculates the estimated axial force F2 _c after allocation.

The adder 145 adds the ideal axial force F1 _c after distribution calculated by the multiplier 142 and the estimated axial force F2 _c after distribution calculated by the multiplier 144 to thereby add the spring component T _sp ^* . The final axial force _{Fsp used} for the calculation is calculated.

<Operation and Effect of Fifth Embodiment>
Therefore, according to the fifth embodiment, the following operations and effects can be obtained.
(8) based on both the absolute value of the absolute value and the axial force difference ΔF of gravity component G _a in the direction along the road gradient, the distribution ratio of the distribution ratio D5 and the estimated axial force F2 from the ideal axial force F1 corrected D6 Is calculated. The absolute value of the absolute value and the axial force difference ΔF of the gravity component G _a, both the actual road surface reaction force (axial force) is reflected. For this reason, the actual road reaction force depends on the degree of inclination of the first inclined path 91a or the second inclined path 91b with respect to the final axial force F _sp and eventually the final input torque T _in ^* . Reflected more appropriately. As a result, a more appropriate target rudder angle θ ^* and target pinion angle θ _p ^* are calculated in accordance with the degree of inclination of the first ramp 91a or the second ramp 91b. Therefore, the driver can steer more naturally. Further, a more appropriate steering feeling can be realized according to the inclination of the first inclined path 91a or the second inclined path 91b.

<Sixth Embodiment>
Next, a sixth embodiment of the steering control device will be described. This embodiment is different from the third embodiment in the point of the calculation method of the axial force distribution calculation unit 83.

As shown in FIG. 15, the axial force distribution calculating unit 83 calculates the estimated axial force in addition to the ideal axial force F1 based on the target pinion angle θ _p ^* and the estimated axial force F2 based on the current value I _b of the turning motor 41. F3 is used to calculate the final axial force _Fsp used for calculating the spring component _Tsp ^* .

In this case, as shown by the two-dot chain line in FIG. 4, the vehicle model 72 is provided with an estimated axial force calculation unit 86 for calculating the estimated axial force F3. The estimated axial force calculation unit 86 calculates the estimated axial force F3 based on the state quantity _{Sx in} which the vehicle behavior or the road surface state (road surface reaction force) is reflected. However, the state quantity S _x is a state quantity other than the current value I _b of the steered motor 41. Examples of the state quantity S _x include the lateral acceleration LA and the yaw rate YR.

The estimated axial force calculation unit 86 calculates an estimated axial force based on the lateral acceleration LA or an estimated axial force based on the yaw rate YR as the estimated axial force F3.
The estimated axial force based on the lateral acceleration LA is obtained by multiplying the lateral acceleration LA detected through the lateral acceleration sensor 502 by a gain that is a coefficient corresponding to the vehicle speed V. The lateral acceleration LA reflects road surface conditions such as road surface frictional resistance. For this reason, the estimated axial force calculated based on the lateral acceleration LA reflects the actual road surface condition.

  The estimated axial force based on the yaw rate YR is obtained by multiplying the yaw rate differential value that is a value obtained by differentiating the yaw rate YR detected through the yaw rate sensor 503 by a vehicle speed gain that is a coefficient corresponding to the vehicle speed V. The vehicle speed gain is set to a larger value as the vehicle speed V increases. The yaw rate YR also reflects road surface conditions such as road surface frictional resistance. Therefore, the estimated axial force calculated based on the yaw rate YR reflects the actual road surface condition.

A specific configuration of the axial force distribution calculation unit 83 is as follows.
As illustrated in FIG. 15, the axial force distribution calculation unit 83 includes distribution ratio calculation units 151 to 153, multipliers 154 to 156, an adder 157, and a calculation unit 158.

The distribution ratio calculation unit 151 calculates the distribution ratio D ₁₁ with respect to an ideal axial force F1 after correction in accordance with the absolute value of the gravity component G _a in the direction along the road gradient. The distribution ratio calculation unit 152 calculates the distribution ratio D ₁₂ for estimating the axial force F2 in accordance with the absolute value of the gravity component G _a. The distribution ratio calculation unit 153 calculates the distribution ratio D ₁₃ for estimating the axial force F3 in accordance with the absolute value of the gravity component G _a.

Multiplier 154, by multiplying the ideal axial force F1 of the corrected and distribution ratio D _11, calculates the ideal axial force F1 _d after allocation. Multiplier 155, by multiplying the estimated axial force F2 and the distribution ratio _{D 12,} calculates the estimated axial force F2 _d after allocation. Multiplier 156, by multiplying the estimated axial force F3 and the distribution ratio _{D 13,} calculates the estimated axial force F3 _d after allocation.

The adder 157 calculates the total axial force F _add by adding the ideal axial force F1 _d after distribution, the estimated axial force F2 _d after distribution, and the estimated axial force F3 _d after distribution.
The calculation unit 158 calculates the total distribution ratio D _add by adding the distribution ratio D ₁₁ , the distribution ratio D ₁₂ , and the distribution ratio D ₁₃ as represented by the following equation (6). The calculation unit 158 then calculates the spring component T _sp ^* by dividing the total axial force F _add calculated by the adder 157 by the total distribution ratio D _add as represented by the following equation (7). Calculate the final axial force _Fsp used.

D _add = D ₁₁ + D ₁₂ + D ₁₃ (6)
F _sp = F _add / D _add (7)
Incidentally, the final axial force _Fsp may be calculated using a plurality of types of estimated axial force F3 (for example, estimated axial force based on the lateral acceleration LA and estimated axial force based on the yaw rate YR). In this case, the vehicle model 72 is provided with a plurality of estimated axial force calculation units that individually calculate a plurality of types of estimated axial forces F3 in addition to the ideal axial force calculation unit 81 and the estimated axial force calculation unit 82. Further, in the axial force distribution calculation unit 83, a distribution ratio calculation unit and a multiplier are provided for each of a plurality of types of estimated axial forces F3. Calculation unit 158, the total axial force F _{the add} to the sum of all the axial force after distribution, divided by the total distribution ratio D _{the add} to the sum of all the distribution ratio, calculates the final axial force F _sp .

The distribution ratio calculation units 151, 152, and 153 may calculate the distribution ratios D ₁₁ , D ₁₂ , and D ₁₃ according to the absolute value of the axial force deviation ΔF instead of the absolute value of the gravity component Ga. Good. The actual road surface reaction force (axial force) is also reflected in the absolute value of the axial force deviation ΔF.

<Operation and Effect of Sixth Embodiment>
Therefore, according to the sixth embodiment, the following operations and effects can be obtained.
(9) based on the absolute value of the absolute value or the axial force difference ΔF of gravity component G _a in the direction along the road gradient, the distribution ratio D _11, and distribution to estimate the axial force F2, F3 with respect to an ideal axial force F1 of the corrected The ratios D ₁₂ and D ₁₃ are calculated. These estimated axial forces F2 and F3 reflect the actual road surface reaction force (axial force). Further, the vehicle behavior is also reflected in the estimated axial force F3 (the estimated axial force based on the lateral acceleration LA or the estimated axial force based on the yaw rate YR). Therefore, the final axial force F _sp, hence on the final input torque T _in ^*, actual road surface reaction force and the vehicle behavior ramps (91a, 91b) better reflect according to the inclination degree of Is done. As a result, a more appropriate target rudder angle θ ^* and target pinion angle θ _p ^* reflecting actual road surface reaction force and vehicle behavior are calculated according to the degree of inclination of the inclined roads (91a, 91b). Therefore, the driver can steer more naturally. Further, a more appropriate steering feeling can be realized according to the inclination of the first inclined path 91a or the second inclined path 91b.

<Other embodiments>
In addition, you may implement the said embodiment as follows.
In the first to sixth embodiments, the target steering reaction force calculation unit 51 calculates the target steering reaction force T ₁ ^* based on the steering torque _Th and the vehicle speed V, but only the steering torque _Th Based on the above, the target steering reaction force T ₁ ^* may be obtained.

In-the first to sixth embodiments, the target steering angle calculating section 52, the target of the target steering reaction force T ₁ ^* and the steering torque T _h steering wheel 11 by using the sum and is the input torque T _in ^* of Although calculates the steering angle theta ^*, the steering torque T _h only, or target steering reaction force T ₁ ^* only may be calculated target steering angle of the steering wheel 11 theta ^* as an input torque T _in ^*.

In the first to sixth embodiments, a configuration in which the differential steering control unit 63 is omitted may be employed as the control device 50. In this case, the pinion angle feedback control unit 64 takes in the target pinion angle θ _p ^* calculated by the steering angle ratio change control unit 62, and causes the actual pinion angle θ _p to follow the fetched target pinion angle θ _p ^* . in order to execute the feedback control of the pinion angle theta _p.

In the first to sixth embodiments, the control device 50 may employ a configuration in which both the differential steering control unit 63 and the steering angle ratio change control unit 62 are omitted. In this case, the target rudder angle θ _* calculated by the target rudder angle calculation unit 52 is used as it is as the target pinion angle (θ _p ^* ). That is, the steered wheels 16 and 16 are steered as much as the steering wheel 11 is operated.

-In 1st-6th embodiment, you may employ | adopt the structure which omitted the estimated axial force calculating parts 82 and 86 and the axial force distribution calculating part 83 as the vehicle model 72 (refer FIG. 4). In this case, the ideal axial force F1 calculated by the ideal axial force calculation unit 81 becomes the final axial force _Fsp as it is.

  In the first to sixth embodiments, the control device 50 includes, for example, first control corresponding to the first ramp 91a and second control corresponding to the second ramp 91b, for example. Only one of them may be performed. Even in this case, an appropriate steering feeling can be obtained when the vehicle travels on either a curved road having a crossing gradient or a straight road having a crossing gradient.

  In the first to sixth embodiments, the steering device 10 may be provided with a clutch. In this case, the steering shaft 12 and the pinion shaft 13 are connected via the clutch 21 as indicated by a two-dot chain line in FIG. As the clutch 21, an electromagnetic clutch that engages / disengages power through energization of the exciting coil is employed. The control device 50 executes intermittent control for switching the intermittent state of the clutch 21. When the clutch 21 is disconnected, the power transmission path between the steering wheel 11 and the steered wheels 16 and 16 is mechanically disconnected. When the clutch 21 is connected, the power transmission between the steering wheel 11 and the steered wheels 16 and 16 is mechanically coupled.

The first to sixth embodiments may be applied to an EPS (electric power steering device) control device that applies a motor torque as an assisting force to a vehicle steering mechanism. The EPS may be of a type that gives assist force to a steering shaft having a pinion shaft (rotating body) that meshes with the steering shaft, or is steered via a pinion shaft (rotating body) that is provided separately from the steering shaft. A type that applies assist force to the shaft may also be used. The EPS control device controls the motor based on a command value calculated according to the steering state. The command value indicates the torque to be generated by the motor. In the EPS control device, through execution of feedback control that causes the pinion angle (steering angle) to follow the target pinion angle (target turning angle) as the target rotation angle, the torque component (of the turning shaft) There is something that calculates (axial force). The target pinion angle is obtained in the same manner as the target rudder angle θ ^* in the first to sixth embodiments. Even in such a control device, when the vehicle is traveling on an inclined road, there is a problem that it is necessary for the driver to continue to apply force to the steering wheel.

<Other technical ideas>
Next, the technical ideas that can be grasped from the respective embodiments will be added below.
(A) A steering control device for controlling a motor, which is a source of driving force applied to a steering mechanism of a vehicle, based on a command value calculated according to a steering state, and for controlling a steering torque applied to a steering wheel. In response, a target driving force calculation unit that calculates a target driving force that is a first component of the command value, and a target rotation angle of a rotating body that rotates in conjunction with the operation of the steering wheel is set to the steering torque and the target driving. A target rotation angle calculation unit that calculates based on an input torque including at least one of the forces, and a driving force that is a second component of the command value through feedback control that matches the actual rotation angle of the rotating body with the target rotation angle A feedback calculation unit that calculates a correction amount; an ideal axial force that acts on the steered wheel based on the target rotation angle, and an axial force that is reflected in the input torque. An ideal axial force calculation unit that calculates an ideal axial force, an estimated axial force calculation unit that calculates an axial force acting on the steered wheels as an estimated axial force based on a state quantity that reflects vehicle behavior or road surface condition, and the ideal A final axis for calculating a final axial force to be reflected in the input torque by adding a value obtained by multiplying an axial force and the estimated axial force by a distribution ratio individually set according to the crossing gradient. A steering control device having a force calculation unit.

DESCRIPTION OF SYMBOLS 11 ... Steering wheel, 12 ... Steering shaft (rotary body), 16 ... Steering wheel, 31 ... Motor, 50 ... Control apparatus (steering control apparatus), 51 ... Target steering reaction force calculating part (1st calculating part), 52 ... Target rudder angle calculation part (second calculation part), 54 ... Steering angle feedback control part (third calculation part), 81 ... Ideal axial force calculation part (fourth calculation part), 82 ... Estimated axial force calculation Unit (sixth arithmetic unit), 85... Correction processing unit (fifth arithmetic unit), 91a... First ramp, 91b... Second ramp, 503... Yaw rate sensor, 127, 136, 145. vessel (arithmetic unit of the 7), D1, D2, D3 , D4, D5, D6 ... distribution ratio, F1 ... ideal axial force, F2 ... estimated axial force, F c _... correction amount (correction axial force), _{G a} ... gravity component, LA ... lateral acceleration (state quantity), V ... vehicle speed, T * ^... steering reaction force command value (finger Value), T h _... steering torque, _{T in *} ^... input torque, T _{1 *} ^... target steering reaction force (first component), T _{2 *} ^... steering angle correction amount (second component), θ _c ^* ... Correction amount (correction angle), θ ^* ... target rudder angle (target rotation angle), θ _s ... steering angle (rotation angle), YR ... yaw rate (state amount), YR _th ... threshold value.

Claims (9)

A steering control device that controls a motor, which is a generation source of driving force applied to a steering mechanism of a vehicle, based on a command value calculated according to a steering state,
A first calculation unit that calculates a first component of the command value in accordance with a steering torque applied to the steering wheel;
A second calculator that calculates a target rotation angle of a rotating body that rotates in conjunction with the operation of the steering wheel based on an input torque including at least one of the steering torque and the first component;
A third computing unit that computes a second component of the command value through feedback control for causing the actual rotational angle of the rotating body to coincide with the target rotational angle;
A fourth calculating unit that calculates an ideal axial force that is an ideal axial force acting on the steered wheel based on the target rotation angle and that is reflected in the input torque;
The ideal axial force is set in a direction along the crossing gradient based on a neutral value of the ideal axial force corresponding to a straight traveling state of the vehicle according to a crossing gradient that is a gradient in a direction perpendicular to the road line. A fifth control unit that offsets the vehicle in a specific direction opposite to the side on which the vehicle deviates from the road due to the gradient; The steering control device according to claim 1,
When the fifth computing unit determines that the vehicle is traveling on the first ramp, which is a curved road having a crossing gradient, based on the state quantity reflecting the turning motion of the vehicle, the road The ideal axial force is determined based on a neutral value of the ideal axial force corresponding to the straight traveling state of the vehicle according to a transverse gradient that is a gradient in a direction perpendicular to the line. Steering control device that offsets to the side where the cross slope is decreasing. The steering control device according to claim 1 or 2,
When the fifth computing unit determines that the vehicle is traveling on the second ramp, which is a straight road having a cross slope, based on the state quantity that reflects the turning motion of the vehicle, The ideal axial force is determined based on a neutral value of the ideal axial force corresponding to the vehicle straight traveling state in accordance with a transverse gradient that is a gradient in a direction perpendicular to the line. A steering control device that offsets to the side where the crossing gradient increases. The steering control device according to any one of claims 1 to 3,
The fifth calculation unit adds a correction angle calculated according to the transverse gradient to the target rotation angle used for calculating the ideal axial force in the fourth calculation unit, A steering control device for offsetting the ideal axial force in the specific direction. The steering control device according to any one of claims 1 to 3,
The fifth calculation unit adds the correction axial force calculated according to the transverse gradient to the ideal axial force calculated by the fourth calculation unit, thereby obtaining the ideal axial force. A steering control device that offsets in a specific direction. The steering control device according to any one of claims 1 to 5,
When the yaw rate as a state quantity that reflects the turning motion of the vehicle detected through the sensor is equal to or greater than a threshold value, the fifth arithmetic unit is a curved road having a crossing gradient. Steering control that determines that the vehicle is traveling on an inclined road and determines that the vehicle is traveling on a second inclined road that is a straight road having a cross slope when the yaw rate is less than the threshold value. apparatus. The steering control device according to any one of claims 1 to 6,
A sixth computing unit that computes an axial force acting on the steered wheel as an estimated axial force based on a state quantity reflecting a vehicle behavior or a road surface state;
A final axial force to be reflected in the input torque is calculated by adding a value obtained by multiplying the ideal axial force and the estimated axial force by a distribution ratio individually set according to the transverse gradient. A seventh control unit. The steering control device according to claim 7, wherein
The seventh calculation unit recognizes the cross gradient based on the gravity component in the direction along the cross gradient calculated from the lateral acceleration, the yaw rate, and the vehicle speed, and the final value increases as the absolute value of the gravity component increases. A steering control device that sets the distribution ratio such that a ratio of the estimated axial force to an axial force becomes larger. The steering control device according to claim 7, wherein
The seventh calculation unit recognizes the cross gradient based on an axial force deviation that is a difference between the ideal axial force and the estimated axial force, and the final axial force increases as the absolute value of the axial force deviation increases. A steering control device that sets the distribution ratio so that the proportion of the estimated axial force in the vehicle is larger.