JP2015074421A - Steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering device capable of suppressing increase in thrust of auxiliary steering means.SOLUTION: The steering device includes: a steering mechanism 3 for steering right and left front wheels FR, FL through a steering wheel 3A; a right wheel-in motor 2B and a left wheel-in motor 2A disposed at the right and left front wheels FR, FL for giving braking force or driving force to the respective wheels FR, FL independently; a power steering unit 4 for giving auxiliary steering torque to assist the steering mechanism 3 with the steering; and a wheel-in motor controller 5 for controlling the right and left wheel-in motors 2B, 2A and making different magnitude of braking force or driving force be applied to the right and left front wheels FR, FL thus generating right and left braking and driving force steering torque for acting in the same direction as the action direction of the auxiliary steering torque and assisting the auxiliary steering torque.

Description

  The present invention relates to a steering apparatus including auxiliary steering means for generating auxiliary steering torque when steering a steered wheel.

  Conventionally, a steering means that steers a pair of left and right steering wheels and a power steering mechanism that assists the steering means are provided. There is known a steering device that applies an auxiliary steering torque for suppressing power to a power steering mechanism by a motor as a drive source (see, for example, Patent Document 1).

JP 2003-220964 A

By the way, in general, at the time of low vehicle speed / large steering angle turning, the deviation between the theoretical Ackermann direction, which is the direction of the speed vector of the tire contact point, and the actual steering direction of the tire becomes large. Each produces a lateral force acting in the vehicle inner direction. This lateral force acts as a cutting moment around the kingpin axis, and even if the driver releases his hand from the steering wheel, the steering wheel may not easily return to the neutral position.
However, in the conventional steering device, the lower the vehicle speed and the larger the steering angle turning, the more the steering wheel is prevented from being pulled in the direction of turning by the auxiliary steering torque. For this reason, the torque required for steering increases as the steering angle increases, and a problem arises that a power steering mechanism having a driving source with a large thrust is required.

  The present invention has been made paying attention to the above problem, and an object thereof is to provide a steering device capable of suppressing an increase in thrust of auxiliary steering means.

In order to achieve the above object, the steering apparatus of the present invention includes steering means, left and right drive wheel independent control means, auxiliary steering torque generation means, and braking / driving force control means.
The steering means steers a pair of left and right steering wheels via a steering wheel.
The left and right driving wheel independent control means is disposed on the pair of left and right steering wheels, and independently applies a braking force or a driving force to each steering wheel.
The auxiliary steering torque generating means applies auxiliary steering torque for assisting the steering of the steering means.
The braking / driving force control means controls the driving wheel independent control means to apply different magnitudes of braking force or driving force to the pair of left and right steering wheels, so that the direction of action of the auxiliary steering torque The left / right braking / driving force steering torque is generated to assist the auxiliary steering torque.

Therefore, in the steering device of the present invention, the driving wheel independent control means is controlled by the braking / driving force control means, and the braking force or driving force of different magnitudes acts on the pair of left and right steering wheels, so that the auxiliary steering torque Left / right braking / driving force steering torque acting in the same direction is generated.
Thereby, the shortage of the auxiliary steering torque applied by the auxiliary steering means can be compensated by the left / right braking / driving force steering torque. For this reason, when the steering angle increases, the driver's steering force burden can be reduced by the left / right braking force steering torque, and the auxiliary steering means need not have a large thrust. As a result, an increase in thrust of the auxiliary steering means can be suppressed.

1 is an overall system diagram illustrating a vehicle to which a steering device according to a first embodiment is applied. It is a flowchart which shows the flow of the braking / driving force control process performed with the wheel-in motor controller of Example 1. FIG. It is a figure which shows the relationship between an auxiliary steering torque target value and a left-right braking / driving force steering torque target value. It is explanatory drawing which shows the inclination of the kingpin axis | shaft at the time of wheel steering. It is explanatory drawing which shows the cutting moment which generate | occur | produces at the time of steering. It is explanatory drawing which shows the left-right braking / driving force steering torque which acts on the vehicle to which the steering device of Example 1 is applied. It is explanatory drawing which shows the auxiliary | assistant steering torque and the left-right braking / driving force steering torque in the vehicle to which the steering apparatus of Example 1 is applied. It is a flowchart which shows the flow of the braking / driving force control process performed with the wheel in motor controller of Example 2. FIG. It is explanatory drawing which shows the auxiliary | assistant steering torque and the left-right braking / driving force steering torque in the vehicle to which the steering apparatus of Example 2 is applied. It is a flowchart which shows the flow of the braking / driving force control process performed with the wheel in motor controller of Example 3. FIG. It is explanatory drawing which shows the auxiliary | assistant steering torque and the left-right braking / driving force steering torque in the vehicle to which the steering apparatus of Example 3 is applied. It is a flowchart which shows the flow of the braking / driving force control process performed with the wheel in motor controller of Example 4. FIG. FIG. 10 is an explanatory diagram showing an auxiliary steering torque and a left / right braking / driving force steering torque at a very low vehicle speed in a vehicle to which the steering device of Embodiment 4 is applied. FIG. 10 is an explanatory diagram showing an auxiliary steering torque and a left / right braking / driving force steering torque at a low vehicle speed and a large steering angle in a vehicle to which the steering device of Example 4 is applied. It is a flowchart which shows the flow of the braking / driving force control process performed with the wheel in motor controller of Example 5. FIG. It is a map which shows the relational characteristic of the amount of steering and the caster trail at the time of steering of a steered wheel It is a map which shows the relational characteristic of a steering amount and the lateral force which acts on a steering wheel. It is a map which shows the relationship characteristic between a steering amount and the scrub radius of a steered wheel.

  EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the steering device of this invention is demonstrated based on Example 1-Example 5 shown in drawing.

(Example 1)
First, the configuration of the steering apparatus according to the first embodiment will be described by dividing it into “an overall system configuration of an applied vehicle” and “a detailed configuration of braking / driving force control processing”.

[Overall system configuration of applicable vehicles]
FIG. 1 is an overall system diagram showing a vehicle to which the steering device of the first embodiment is applied. Hereinafter, an overall system configuration of a vehicle to which the steering apparatus of the first embodiment is applied will be described with reference to FIG.

  The vehicle 1 shown in FIG. 1 includes left and right front wheels (a pair of left and right steering wheels) FL and FR, left and right rear wheels (driven wheels) RL and RR, and a left wheel-in motor (left and right drive wheels independent) built in the left front wheel FL. Control means) 2A, right wheel-in motor (right and left drive wheel independent control means) 2B built in the right front wheel FR, steering mechanism (steering means) 3, power steering device (auxiliary steering torque generating means) 4, And a wheel-in motor controller (braking / driving force control means) 5.

  The left wheel-in motor 2A and the right wheel-in motor 2B are AC motors that allow a three-phase synchronous motor and a three-phase induction motor, respectively, and can perform a power running operation during acceleration and a regenerative operation during deceleration. During power running, the left and right front wheels FL and FR are driven independently from each other by the current from the battery (nickel metal hydride battery or lithium ion battery) 6. Further, during the regenerative operation, the battery 6 is charged by rotating the left and right front wheels FL and FR independently of each other in the reverse direction of driving. At this time, braking force (regenerative braking) acts on the left and right front wheels FL and FR, respectively. “Driving independently of each other” or “reversely rotating independently of each other” means that different currents are supplied to the left in-wheel motor 2A and the right in-wheel motor 2B. This means that the output torque and the output torque from the right in-wheel motor 2B can be made different. Thereby, each wheel FL, FR can generate different driving force and braking force (regenerative force) with respect to the road surface.

The steering mechanism 3 includes a steering wheel 3A, a steering shaft 3B, and a rack and pinion 3C.
The steering wheel 3A is provided in the vehicle interior and is rotated by a driver.
One end of the steering shaft 3B is connected to the steering wheel 3A, and a pinion gear (not shown) provided at the other end meshes with a rack gear (not shown) of the rack and pinion 3C, and responds to the rotation operation of the steering wheel 3A. And the rack and pinion 3C is reciprocated in the vehicle width direction.
The rack and pinion 3C has one end connected to the left front wheel FL via the left tie rod 3DL, the other end connected to the right front wheel FR via the right tie rod 3DR, and a rack gear (not shown) extending in the axial direction in the middle portion. )have. Then, the pinion gear at the tip of the steering shaft 3B meshed with the rack gear rotates to reciprocate in the vehicle width direction and steer the left and right front wheels FL and FR.

The power steering device 4 includes an actuator 4A that applies an assist force for assisting a steering operation to the steering system, and a power steering controller 4B that controls the operation of the actuator 4A.
The actuator 4A is a three-phase AC brushless motor arranged coaxially with the steering shaft 3B, and is driven by receiving supply of driving power from the power steering controller 4B. At this time, the torque loaded from the actuator 4 </ b> A to the steering shaft 3 </ b> B is auxiliary steering torque that assists the steering of the steering mechanism 3. The magnitude of this auxiliary steering torque is set according to at least the steering angle.

The wheel-in motor controller 5 includes an accelerator opening sensor 8A, a vehicle speed sensor (vehicle speed detection means) 8B, a steering angle sensor (steering angle detection means) 8C, and a driver steering torque sensor (driver steering torque detection means) 8D. Various detection signals from the brake pedal sensor 8E are input.
The accelerator opening sensor 8A detects the amount of depression of an accelerator pedal (not shown).
Further, the vehicle speed sensor 8B detects the speed of the vehicle 1. Here, the rotational speed sensor is configured to detect the rotational speeds of the left and right rear wheels RL and RR that are driven wheels.
The steering angle sensor 8C detects the rotation angle of the steering wheel 3A that is the steering angle of the steering mechanism 3, that is, the rotation angle of the steering shaft 3B.
The driver steering torque sensor 8D detects a steering torque (driver steering torque) by the driver, which is a torque acting on the steering shaft 3B when the driver operates the steering wheel 3A. The driver steering torque is a value obtained by subtracting the auxiliary steering torque added by the power steering device 4 from the torque acting on the steering shaft 3B.
The brake pedal sensor 8E detects the amount of depression of a brake pedal (not shown).

  The wheel-in motor controller 5 includes a braking / driving force target value of the left wheel-in motor 2A that satisfies the driver's required driving force that appears in the accelerator opening and the driver's required braking force that appears in the brake pedal depression amount, and the right wheel. The braking / driving force target value of the in-motor 2B is calculated. Then, a braking / driving force command signal is output to the left inverter (left wheel-in motor driving circuit) 7A and the right inverter (right wheel-in motor driving circuit) 7B so as to realize the braking / driving force target value. The left and right inverters 7A and 7B control the amount of electric power supplied from the battery 6 based on the braking / driving force command signal, and as a result, the braking / driving forces of the left and right wheel-in motors 2A and 2B are controlled.

The wheel-in motor controller 5 is supplied with a signal of the auxiliary steering torque target value Tp ^* of the power steering 4 from the power steering controller 4B. Then, the left / right braking / driving force steering torque target value Tfx ^* is calculated based on the input auxiliary steering torque target value Tp ^* , and the left / right front wheels FL, FR are calculated according to the left / right braking / driving force steering torque target value Tfx ^*. The target value of the braking / driving force to be applied to each is corrected. The calculation of the left / right braking / driving force steering torque target value Tfx ^* and the braking / driving force target value (braking / driving force control processing) will be described later.
Here, the “left / right braking / driving force steering torque” is generated by applying braking force or driving force of different magnitudes to the left and right front wheels FL, FR, and the auxiliary steering torque loaded by the power steering device 4. This is the torque acting in the same direction as the acting direction, i.e., the direction assisting this auxiliary steering torque.

[Detailed configuration of braking / driving force control processing]
FIG. 2 is a flowchart illustrating the flow of braking / driving force control processing executed by the wheel-in motor controller according to the first embodiment. The detailed configuration of the braking / driving force control process according to the first embodiment will be described below with reference to FIG.

  In step S1, the steering angle by the steering mechanism 3 is detected, and the process proceeds to step S2. Here, the steering angle is detected by the steering angle sensor 8C.

In step S2, following the detection of the steering angle in step S1, a necessary auxiliary steering torque target value T ^* determined according to the magnitude of the steering angle is set, and the process proceeds to step S3.
The relational characteristic between the steering angle and the required auxiliary steering torque target value T ^* is stored in the wheel-in motor controller 5 in advance.

In step S3, following setting of the required auxiliary steering torque target value T ^* in step S2, a target value Tp ^* of auxiliary steering torque loaded by the power steering device 4 is set, and the process proceeds to step S4.
Here, the auxiliary steering torque target value Tp ^* is set to be a predetermined ratio (for example, 70%) with respect to the necessary auxiliary steering torque target value T ^* . Here, the ratio of the auxiliary steering torque target value Tp ^* is set to be lower as the required auxiliary steering torque target value T ^* is higher.

In step S4, following the setting of the auxiliary steering torque target value Tp ^* in step S3, it is determined whether or not the auxiliary steering torque target value Tp ^* set in step S3 acts in the direction of turning the steering wheel 3A. To do. If YES (acting in the steering wheel cutting direction), the process proceeds to step S5. If NO (acting in the steering wheel cutback direction), the process proceeds to step S6.
Here, the fact that the auxiliary steering torque target value Tp ^* is in the cutting direction is determined by the increase / decrease state of the steering angle detected by the steering angle sensor 8C. That is, if the steering angle is increased, the steering wheel 3A is operated in the cutting direction, and it is determined as YES because the auxiliary steering torque is also applied in the cutting direction. On the other hand, if the steering angle is decreased, the steering wheel 3A is operated in the return direction, and it is determined as NO because the auxiliary steering torque is also applied in the return direction.

In step S5, following the determination that the auxiliary steering torque target value Tp ^* in step S4 is applied in the cutting direction, the steering wheel 3A is adjusted according to the magnitude of the auxiliary steering torque target value Tp ^* set in step S3. The left / right braking force steering torque target value Tfx ^* acting in the cutting direction is set, and the process proceeds to step S7.

In step S6, following the determination that the auxiliary steering torque target value Tp ^* in step S4 acts in the return direction, the steering wheel 3A is selected according to the magnitude of the auxiliary steering torque target value Tp ^* set in step S3. The left / right braking force steering torque target value Tfx ^* that acts in the direction of switching back is set, and the process proceeds to step S7.
Here, the magnitude of the left / right braking force steering torque target value Tfx ^* in step S5 and step S6 is the auxiliary steering torque target value Tp set in step S3 from the required auxiliary steering torque target value T ^* set in step S2. The absolute value of the value after subtracting ^* .
At this time, as shown in FIG. 3, the left / right braking force steering torque target value Tfx ^* is set to a larger value as the auxiliary steering torque target value Tp ^* increases.

In step S7, following the setting of the left / right braking force steering torque target value Tfx ^* in step S5 or step S6, a left / right braking / driving force difference target value Fxgap ^* is calculated, and the process proceeds to step S8.
Here, the left / right braking / driving force difference target value Fxgap ^* is the same in the opposite direction to the left / right front wheels FL, FR, which are the left and right steering wheels, in order to realize the set left / right braking force steering torque target value Tfx ^*. This is set assuming that the braking / driving force (= 1/2 × Fxgap ^* ) is added. That is, based on the relationship of the following formula (1), the left / right braking / driving force difference target value Fxgap ^* is calculated from the value of the left / right braking force steering torque target value Tfx ^* .
Here, “s” is a scrub radius (constant) in the left and right front wheels FL, FR. “Η _in ” is the link efficiency of the inner ring. “Η _out ” is the link efficiency of the outer ring. “R _knu ” is the knuckle arm radius. “R _pin ” is the distance (moment length) from the center position of the pinion gear provided on the steering shaft 3B to the center position of the rack gear provided on the rack and pinion 3C.

In step S8, following the calculation of the left / right braking / driving force difference target value Fxgap ^* in step S7, input from the accelerator pedal and brake pedal (depression amount) and vehicle conditions such as vehicle speed, acceleration, and yaw rate are detected. Proceed to S9.

In step S9, following the pedal input and vehicle state detection in step S8, the left / right braking / driving force total target value Fxtotal ^* is set based on the detected pedal input and the like, and the process proceeds to step S10.
Here, the “total left / right braking / driving force target value” means that the left and right front wheels FL, FR are loaded based on the required driving force appearing in the accelerator opening, the required braking force appearing in the brake depression amount, and other vehicle conditions such as the vehicle speed. This is the total target value of braking force or driving force.

In step S10, following the setting of the left / right braking / driving force total target value Fxtotal ^* in step S9, the left / right braking / driving force total target value Fxtotal ^* and the left / right braking / driving force difference target value Fxgap ^* calculated in step S7 are set. Based on this, the braking / driving force target values of the left and right wheel-in motors 2A and 2B are set, and the process proceeds to the end.
A braking / driving force command signal is output to the left and right inverters 7A and 7B based on the braking / driving force target value, and the braking / driving forces of the left and right wheel-in motors 2A and 2B are independently controlled.

Next, the operation will be described.
First, “the problem at the time of steering with a large steering angle” will be described, and subsequently, “the steering assist action” in the steering device of the first embodiment will be described.

[Problems when steering large steering angles]
FIG. 4 is an explanatory diagram showing the inclination of the kingpin shaft during wheel steering. FIG. 5 is an explanatory diagram showing a cutting moment generated during steering. Hereinafter, the problem at the time of large steering angle steering will be described with reference to FIGS. 4 and 5.

Generally, when the steering angle is large in the vehicle, the turning angle of the steered wheels is large. That is, at the time of steering, the steered wheel T rotates so as to be in a state along the vehicle width direction indicated by the broken line in FIG. 4 from the state facing the traveling direction indicated by the solid line in FIG. At this time, the steered wheel T becomes closer to a state along the vehicle width direction as the steering angle is larger, and the kingpin axis K is inclined. Then, due to the inclination angle α of the kingpin axis K, the steered wheel T greatly depresses the ground G (indicated by G ′ in FIG. 4), and the force depressing the vehicle body (indicated by arrow F in FIG. 4) increases. As a result, the steering torque increases. As a result, the steering force required for turning the steering wheel increases, and the steering wheel becomes heavy.
In addition, when the vehicle speed is high, the action of canceling the heavy steering wheel may work. However, when the vehicle speed is very low (nearly vehicle speed is zero), that is, when the steering wheel is cut at the stationary position, this is canceled. The action does not work. Therefore, in the stationary state, the necessary steering torque is greatly increased, and the steering wheel may become heavier (becomes difficult to cut).

Further, although the vehicle speed is not zero, at the time of low vehicle speed / large steering angle steering, the theoretical Ackermann direction (indicated by an arrow A in FIG. 5) that is the direction of the speed vector at the contact point P where the steering wheel T contacts the ground, and the steering wheel A deviation (slip angle θ) occurs between T and the actual steering direction (indicated by a broken line B in FIG. 5). When the slip angle θ is generated, a lateral force (or cornering force: indicated by an arrow C in FIG. 5) is generated on each of the pair of left and right steering wheels T in the vehicle inner direction.
Here, the generation point of the lateral force (cornering force) C is separated from the wheel center from the pneumatic trail, and the kingpin shaft grounding point (indicated by K ′ in FIG. 5) is the trail at the time of turning (FIG. 5). The distance is indicated by C1). The “steering time trail C1” is obtained as the sum of the turning caster trail and the pneumatic trail. Then, the lateral force (cornering force) C is separated from the kingpin shaft ground contact point K ′, so that the lateral force (cornering force) C is a moment around the kingpin shaft (arrow D in FIG. 5). Act as).

  Here, it is known that the slip angle θ increases as the vehicle has a low vehicle speed and a large steering angle, and the lateral force (cornering force) C increases as the slip angle θ increases. Therefore, the moment D about the kingpin axis acting on each of the pair of left and right steering wheels T increases as the vehicle speed decreases and the steering angle increases. Moreover, in the large steering angle region, the moment D acts on the steering wheel H in the cutting direction for both the left and right wheels. Therefore, even if the driver releases his hand from the steering wheel H during steering, the steering wheel H is unlikely to return to the neutral position. It may be cut to the maximum turning angle.

  Note that the steering wheel becomes heavier (harder to cut) and the steering wheel H is less likely to return to the neutral position, but in the case of a general suspension model, the steering wheel H is The effect of making it difficult to return to the position has a greater effect.

  Thus, since the driver's steering force burden increases at low vehicle speeds and large steering angles, the driver's steering force burden cannot be reduced unless a power steering device having a large thrust is used. However, if the thrust of the power steering device is increased, there is a problem that the cost increases.

[Steering assist function]
FIG. 6 is an explanatory diagram illustrating a left / right braking / driving force steering torque that acts on a vehicle to which the steering device according to the first embodiment is applied. FIG. 7 is an explanatory diagram illustrating an auxiliary steering torque and a left / right braking / driving force steering torque in a vehicle to which the steering device of the first embodiment is applied. Hereinafter, based on FIG.6 and FIG.7, the steering assistance effect | action in the steering apparatus of Example 1 is demonstrated.

In the steering device of the first embodiment, for example, when the auxiliary steering torque (indicated by arrow E in FIG. 6) by the power steering device 4 acts in the direction of turning back the steering wheel 3A, the steering wheel 3A is applied to the left front wheel FL. A left braking / driving force indicated by an arrow L is applied by the left wheel-in motor 2A so that a rotational moment (indicated by an arrow J) about the kingpin axis K acting in the direction of turning back is applied. On the other hand, a right braking drive indicated by an arrow N by the right wheel-in motor 2B is applied to the right front wheel FR so that a rotational moment (indicated by an arrow M) around the kingpin axis K acting in the direction of turning back the steering wheel 3A acts. Power is loaded.
Here, the left braking / driving force L and the right braking / driving force N are forces of different magnitudes acting in opposite directions, and generate rotational moments J and M acting in the same direction as the direction of operation of the auxiliary steering torque E. Let That is, the left / right braking / driving forces L and N are not braking / driving forces applied to improve the steering behavior of the vehicle 1 in accordance with the steering of the steering wheel 3A.

  The rotation moments J and M become the left / right braking / driving force steering torque acting in the direction of turning back the steering wheel 3A via the rack and pinion 3C, and assist the auxiliary steering torque E of the power steering device 4. .

That is, the rotational moment J, M (= left / right braking / driving force steering torque) is added to the auxiliary steering torque by the power steering device 4. As a result, as shown in FIG. 7, the auxiliary steering torque necessary for assisting the driver's steering force during steering (hereinafter referred to as “necessary auxiliary steering torque”) is a value indicated by a broken line. The auxiliary steering torque (shown by a solid line in FIG. 7) by the power steering device 4 can be reduced with respect to the steering torque.
As a result, it is possible to reduce the load on the power steering device 4 and suppress the increase in thrust of the actuator 4A while securing the necessary auxiliary steering torque to prevent the driver from increasing the steering force load. Further, it is possible to avoid an increase in cost by suppressing an increase in thrust of the actuator 4A.

Next, the effect will be described.
In the steering device of the first embodiment, the following effects can be obtained.

(1) Steering means (steering mechanism) 3 for steering a pair of left and right steering wheels (left and right front wheels FL, FR) via a steering wheel 3A;
Left and right driving wheel independent control means (left wheel-in motor, right wheel-in motor) disposed on the pair of left and right steering wheels FL and FR and independently applying braking force or driving force to the respective steering wheels FL and FR 2A, 2B,
Auxiliary steering torque generating means (power steering device) 4 for applying auxiliary steering torque for assisting steering of the steering means 3;
By controlling the driving wheel independent control means 2A, 2B and applying a braking force or a driving force of different magnitudes to the pair of left and right steering wheels FL, FR, the same direction as the direction of the auxiliary steering torque is applied. Braking / driving force control means (foil-in motor controller) 5 that generates a left / right braking / driving force steering torque that acts on the direction and assists the auxiliary steering torque;
It was set as the structure provided with.
Thereby, it is possible to suppress an increase in thrust of the auxiliary steering means while preventing an increase in the driver's steering force burden.

(Example 2)
The second embodiment is an example in which the left / right braking / driving force steering torque is generated when the steering angle is equal to or greater than a predetermined steering angle.

  FIG. 8 is a flowchart showing the flow of braking / driving force control processing executed by the wheel-in motor controller of the second embodiment. Hereinafter, based on FIG. 8, the detailed structure of the braking / driving force control process of Example 2 is demonstrated. The same steps as those in the braking / driving force control process of the first embodiment are denoted by the same step numbers as those in the flowchart shown in FIG.

In step S2A, following the necessary steering assist torque target value T ^* set at step S2, the absolute value of the steering angle detected in step S1 is determined whether a threshold angle theta ₀ or a preset. If YES (θ ₀ ≦ detected steering angle), the steering angle is large and the driver's steering force burden is large. Therefore, the power steering device 4 alone cannot provide the necessary auxiliary steering torque, and the process proceeds to step S3. In the case of NO (θ ₀ > detected steering angle), the steering angle is small and the driver's steering force burden is small. Therefore, it is assumed that the necessary auxiliary steering torque can be provided only by the power steering device 4, and the process proceeds to step S8.
Here, the threshold angle θ ₀ is an angle determined as a large steering angle, and can be set to an arbitrary value. Here, the angle is set to 60 °.

  FIG. 9 is an explanatory diagram showing an auxiliary steering torque and a left / right braking / driving force steering torque in a vehicle to which the steering device of the second embodiment is applied. Hereinafter, based on FIG. 9, the steering assist operation in the steering device of the second embodiment will be described.

In the steering device of the second embodiment, as shown in the flowchart shown in FIG. 8, first, the steering angle is detected. When the absolute value of the steering angle is equal to or larger than a preset threshold angle θ ₀ , auxiliary steering by the power steering device 4 is performed. A left / right braking / driving force steering torque acting in the same direction as the torque is generated. When the absolute value of the steering angle is less than the threshold angle θ ₀ , the driver's steering force is assisted only by the auxiliary steering torque by the power steering device 4.

Accordingly, as shown in FIG. 9, in the region where the steering angle is small and the driver's steering force load is small (when the steering angle is less than the threshold angle θ ₀ and the necessary auxiliary steering torque is small), the left and right wheel-in motors 2A, 2B It is not necessary to perform cooperative control between the left / right braking / driving force steering torque generated by the left / right braking / driving force generated by controlling the power and the auxiliary steering torque by the power steering device 4. Therefore, it is possible to reduce the driver's steering force burden with high accuracy and ease.

On the other hand, in a region where the driver's steering force burden is large at a large steering angle (when the steering angle is greater than or equal to the threshold angle θ ₀ and the required auxiliary steering torque is large), the left / right braking / driving force steering torque is converted to the auxiliary steering torque by the power steering device 4. The increase in the auxiliary steering torque by the power steering device 4 can be suppressed. Therefore, the necessary auxiliary steering torque can be ensured without increasing the thrust of the power steering device 4.

  As described above, in the steering device according to the second embodiment, the following effects can be obtained.

(2) Provided with a steering angle detection means (steering angle sensor) 8C for detecting the steering angle of the steering means (steering mechanism) 3;
The braking / driving force control means (foil-in motor controller) 5 is configured to generate the left / right braking / driving force steering torque when the steering angle is equal to or larger than a predetermined value (threshold angle θ ₀ ).
Thus, in addition to the effect of (1) above, when the driver steering load is small, cooperative control of the left / right braking / driving force steering torque and the auxiliary steering torque by the power steering device 4 is not performed, and the driver's steering can be easily performed with high accuracy. Force assistance can be performed. Further, when the driver steering burden is large, the left and right braking / driving force steering torque is added to the auxiliary steering torque by the power steering device 4, and the necessary auxiliary steering torque can be secured while suppressing the increase in thrust of the power steering device 4.

(Example 3)
The third embodiment is an example in which the necessary auxiliary steering torque and the threshold angle are set based on the steering angle and the vehicle speed.

  FIG. 10 is a flowchart illustrating the flow of braking / driving force control processing executed by the wheel-in motor controller according to the third embodiment. Hereinafter, based on FIG. 10, the detailed structure of the braking / driving force control process of Example 3 is demonstrated. Steps similar to the braking / driving force control process of the first embodiment or the braking / driving force control process of the second embodiment are denoted by the same step numbers as those in the flowchart shown in FIG. 2 or FIG. To do.

In step S1A shown in FIG. 10, following the detection of the steering angle in step S1, the vehicle speed of the vehicle 1 is detected, and the process proceeds to step S2B.
Here, the vehicle speed is detected by detecting the rotational speeds of the left and right rear wheels RL and RR with a rotational speed sensor constituting the vehicle speed sensor 8B, and multiplying the arithmetic average of the rotational speeds of the wheels by the circumferential length of the tire with the same radius. calculate. In addition, when it has a means to detect separately vehicle conditions, such as a steering angle, a yaw rate, and an acceleration, you may correct | amend the vehicle speed calculated using these values.

In step S2B, following the detection of the vehicle speed in step S1A, the required auxiliary steering torque target value T ^* and the threshold angle θ according to the magnitude of the steering angle detected in step S1 and the magnitude of the vehicle speed detected in step S1B. ₀ is calculated, and the process proceeds to step S2A.
Here, in general, in a vehicle, as the vehicle speed increases, the self-restoring force (force for returning the steering wheel to a neutral position (= zero steering angle)) that is generated when the wheels are steered tends to increase. The self-restoring force is a preferable action that contributes to the steering stability at high speed. Therefore, it is not necessary to cancel this self-restoring force by the auxiliary steering torque.
Therefore, the necessary auxiliary steering torque target value T ^* is set to a smaller value as the vehicle speed increases. On the other hand, even when the required auxiliary steering torque target value T ^* is small, the threshold angle θ ₀ is high when the upper limit value of the auxiliary steering torque by the power steering device 4 is made constant. Therefore, as shown in FIG. 11, the necessary auxiliary steering torque target value T ^* and the threshold angle θ ₀ are set according to the steering angle and the vehicle speed.

The required auxiliary steering torque target value T ^* may be changed in magnitude according to the driver steering torque detected by the driver steering torque sensor 8D. In other words, it sets the driver steering torque is small enough required steering assist torque target value T ^* to a small value, set to a larger value the higher the required steering assist torque target value T ^* driver steering torque is large.

Thus, by setting the necessary auxiliary steering torque target value T ^* and the threshold angle θ _{0 according} to the steering angle and the vehicle speed, the necessary auxiliary steering torque changes according to the vehicle state that changes depending on the vehicle speed and the steering amount. In consideration of this, the magnitude of the left / right braking / driving force steering torque can be set. That is, it is possible to generate the right / left braking / driving force steering torque having an appropriate magnitude according to the vehicle state such as the steering angle and the vehicle speed. Thus, the driver's steering force burden can be appropriately reduced without using the large thrust power steering device 4.

  As described above, in the steering device according to the third embodiment, the following effects can be obtained.

(3) steering angle detection means (steering angle sensor) 8C for detecting the steering angle of the steering means (steering mechanism) 3;
Vehicle speed detecting means (vehicle speed sensor) 8B for detecting the vehicle speed;
A driver steering torque detecting means (driver steering torque sensor) 8D for detecting a steering torque from the driver, and at least one of them,
The braking / driving force control means (wheel-in motor controller) 5 is configured to set the magnitude of the left / right braking / driving force steering torque based on at least one of the magnitude of the steering angle, the vehicle speed, and the driver steering torque. did.
Thereby, in addition to the effect of (1) or (2) above, the right / left braking / driving force steering torque having an appropriate magnitude according to the vehicle state can be set, and the power steering device 4 having a large thrust is not used. The driver's steering force burden can be reduced appropriately.

Example 4
The fourth embodiment is an example in which the magnitude of the necessary auxiliary steering torque is changed according to the magnitude of the vehicle speed.

  FIG. 12 is a flowchart illustrating a flow of braking / driving force control processing executed by the wheel-in motor controller according to the fourth embodiment. Hereinafter, based on FIG. 12, the detailed structure of the braking / driving force control process of Example 4 is demonstrated. In addition, about the step similar to the braking / driving force control process of Example 1-Example 3, the same step number as the flowchart shown in FIG.2, FIG.8, FIG.10 is attached | subjected and detailed description is abbreviate | omitted.

At step S1B shown in FIG. 12, following the detection of the vehicle speed in step S1A, it is determined whether the vehicle speed is first less than the threshold vehicle speed V ₀ that is set in advance. If YES (vehicle speed <V ₀ ), the process proceeds to step S1C. If NO (vehicle speed ≧ V ₀ ), the process proceeds to step S1D.
Here, the “first threshold vehicle speed V ₀ ” is a value at which the vehicle speed is close to zero and can be determined as a very low vehicle speed.

In step S1C, following the determination that vehicle speed <V ₀ in step S1B, the necessary auxiliary steering torque target value to be applied when the steering wheel 3A is steered in the cutting direction (hereinafter referred to as the necessary auxiliary steering torque target value T ₀ during cutting). ^And a required auxiliary steering torque target value to be applied when the steering wheel 3A is steered in the return direction (hereinafter referred to as a required auxiliary steering torque target value T _0- ^* at the time of return), and step S2A Proceed to
Here, in a very low vehicle speed range, a steering force increase phenomenon occurs when the steering wheel is fully closed. Therefore, as shown in FIG. 13, the required auxiliary steering torque target value T ₀ ^{+ *} for turning is set to a value larger than the required auxiliary steering torque target value T ₀ ^{− * for} returning.

In step S1D, subsequent to the judgment of the vehicle speed ≧ V ₀ in step S1B, the vehicle speed detected by the step S1A is equal to or smaller than the second threshold vehicle speeds V ₁ to a preset. If YES (vehicle speed <V ₁ ), the process proceeds to step S1E. If NO (vehicle speed ≧ V ₁ ), the process proceeds to step S2A.
Here, the “second threshold vehicle speed V ₁ ” is a value that is larger than the first threshold vehicle speed V ₀ and is a value by which it can be determined that the steering wheel self-restoring force is small (it is difficult for the steering wheel 3A to return to the neutral position). It is.

In step S1E, subsequent to the judgment of the vehicle speed <V ₁ at step S1D, the steering angle detected by the step S1 it is determined whether a large steering angle determined angle theta ₁ or more preset. If YES (steering angle ≧ θ ₁ ), the process proceeds to step S1F. If NO (steering angle <θ ₁ ), the process proceeds to step S2A.
Here, the “large steering angle determination angle θ ₁ ” is an angle at which it can be determined that the cutting moment increases due to a large Ackermann shift (slip angle θ).

In step S1F, following the determination that the steering angle ≧ θ ₁ in step S1E, the necessary auxiliary steering torque target value (hereinafter referred to as the necessary auxiliary steering torque target value T at the time of turning) applied when the steering wheel 3A is steered in the turning direction. ₁ ^{+ *} ) and a required auxiliary steering torque target value (hereinafter referred to as a required auxiliary steering torque target value T _1- ^* at the time of return) applied when the steering wheel 3A is steered in the return direction. Proceed to S2A.
Here, in a low vehicle speed / large steering angle region, a phenomenon in which a rotational moment acts in the cutting direction of the steering wheel H occurs. Therefore, as shown in FIG. 14, the large steering angle region (when the steering angle ≧ theta _1), switching back when required steering assist torque target value T ₁ ^{- *} the required steering assist torque target value when the cut T ₁ Set to a value greater than ^{+ *} .

Thus, when the vehicle speed is very low (the vehicle speed is almost zero), the required auxiliary steering torque target value T ₀ ⁺⁺ at the time of turning is set larger than the required auxiliary steering torque target value T ₀ ^{− *} at the time of turning back, so that The braking / driving force steering torque is also larger at the time of cutting than at the time of switching back.
As a result, the left / right braking / driving force steering torque added to the auxiliary steering torque by the steering device 4 can be further increased when the steering wheel 3A is cut at a very low vehicle speed. As a result, an increase in thrust of the steering device 4 can be effectively suppressed while reducing the driver's steering force burden.

On the other hand, although the vehicle speed is higher than the extremely low vehicle speed, when it is determined that the vehicle speed is low, the required auxiliary steering torque target value T _1- ^* at the time of switching back is determined when the steering angle is determined to be a large steering angle. It is made larger than the target value T ₁ ^{+ *} . As a result, the left / right braking / driving force steering torque also has a larger value at the time of switching back than at the time of cutting at a large steering angle. In FIG. 14, the left / right braking / driving force steering torque is zero when the large steering angle is cut.
As a result, when the steering wheel 3A is difficult to return to the neutral position at the low vehicle speed and large steering angle, the left / right braking / driving force steering torque added to the auxiliary steering torque by the steering device 4 can be further increased. As a result, an increase in thrust of the steering device 4 can be effectively suppressed while reducing the driver's steering force burden.

  As described above, in the steering device of the fourth embodiment, the effects listed below can be obtained.

(4) Steering angle detection means (steering angle sensor) 8C for detecting the steering angle of the steering means (steering mechanism) 3;
Vehicle speed detection means (vehicle speed sensor) 8B for detecting the vehicle speed,
The braking-driving force control unit (wheel-in motor controller) 5, when the first less than the threshold vehicle speed V ₀ the vehicle speed is set in advance, than the left and right driving force steering torque when the steering direction switching back the steering means 3 The left and right driving force steering torque is increased when the steering means 3 is steered in the cutting direction.
Thereby, in addition to the effect of any one of the above (1) to (3), even when the driver's steering force load is large at the time of stationary, the driver's steering force load is reduced and the steering device 4 is reduced. An increase in thrust can be effectively suppressed.

(5) The braking / driving force control means (foil-in motor controller) 5 is configured to control the steering means (steering mechanism) when the vehicle speed is equal to or higher than the first threshold vehicle speed V _{0 and} lower than a preset second threshold vehicle speed V _1. ) When the steering angle of 3 is equal to or greater than a predetermined value (large steering angle determination angle) θ ₁ , the steering means 3 is turned back more than the left and right driving force steering torque when the steering means 3 is steered in the turning direction. The left and right driving force steering torque when the vehicle is steered to be increased.
As a result, in addition to the effect of (4), even when the steering wheel 3A is difficult to return to the neutral position at a low vehicle speed and a large steering angle, the thrust of the steering device 4 is increased while reducing the driver's steering force burden. Can be effectively suppressed.

(Example 5)
The fifth embodiment is an example in which the magnitude of the left / right braking / driving force steering torque is changed according to the wheel load, trail, and scrub radius of the left and right front wheels.

  FIG. 15 is a flowchart illustrating a flow of braking / driving force control processing executed by the wheel-in motor controller according to the fifth embodiment. The detailed configuration of the braking / driving force control process according to the fifth embodiment will be described below with reference to FIG. The same steps as those in the braking / driving force control process of the first to fourth embodiments are denoted by the same step numbers as those in the flowcharts shown in FIGS. 2, 8, 10, and 12, and detailed description thereof is omitted. To do.

In step S1G shown in FIG. 15, following the detection of the vehicle speed in step S1A, the wheel loads of the left and right front wheels FL and FR are calculated separately on the left and right, and the process proceeds to step S1H.
Here, the wheel load is calculated by a well-known method from the suspension strokes of the left and right front wheels FL and FR and the suspension spring / damper characteristics of the left and right front wheels FL and FR. The suspension stroke is detected by a sensor (not shown).

In step S1H, following the calculation of the wheel load in step S1G, caster trails for turning the left and right front wheels FL and FR are set, and the process proceeds to step S1J.
Here, the caster-rail at the time of steering is preset according to the steering angle detected in step S1, and is stored in the wheel-in motor controller 5 as a map shown in FIG. That is, in this step S1H, the right and left caster trails are individually set on the left and right sides based on the map and the steering angle shown in FIG.

In step S1J, the lateral force acting on the left and right front wheels FL and FR is set subsequent to the setting of the caster rail during turning in step S1H, and the process proceeds to step S2B.
Here, the lateral force acting on the left and right front wheels FL and FR is set in advance according to the steering angle detected in step S1 and the vehicle speed detected in step S1A, and the wheel-in motor is represented as a map shown in FIG. It is stored in the controller 5. That is, in this step S1J, the lateral force acting on the left and right front wheels FL, FR is set individually on the left and right sides based on the map of FIG. 17, the steering angle, and the vehicle speed.

In step S2B, following the setting of the lateral force in step S1J, the required auxiliary steering torque target value T ^* and the threshold angle according to the magnitude of the steering angle detected in step S1 and the magnitude of the vehicle speed detected in step S1B. θ ₀ is calculated, and the process proceeds to step S2A.
Further, in step S2B shown in FIG. 15, the necessary auxiliary steering torque is taken into consideration in consideration of the wheel load calculated in step S1G, the caster rail at the time of turning set in step S1H, and the lateral force set in step S1J. The target value T ^* is corrected.
Here, the required steering torque target value T ^* is corrected so as to increase as the wheel load increases. This is because the larger the wheel load, the more susceptible to disturbances such as road surface unevenness. Moreover, it correct | amends so that required steering torque target value T ^* may become small, so that the caster-rail at the time of steering and lateral force are large. This is because the integrated value of the caster rail at the time of turning and the lateral force acts on the rotational moment around the kingpin axis, and the rotational moment increases as the caster rail at the time of turning or the lateral force increases.

Further, in step S7A, following the setting of the left / right braking force steering torque target value Tfx ^* in step S5 or step S6, the scrub radii of the left and right front wheels FL, FR are individually set, and the process proceeds to step S7.
Here, the scrub radii of the left and right front wheels FL, FR vary with respect to the steering angle as shown in FIG. That is, the scrub radii for the left and right front wheels FL and FR are set based on the steering angle detected in step S1 and the map shown in FIG. In this figure, the amount of change is slight, but the scrub radius is generally several tens of mm or less in the first place. Therefore, even if the amount of change is small, the influence on the left / right braking / driving force steering torque is large.

In step S7, following the setting of the scrub radius in step S7A, the left / right braking / driving force difference target value Fxgap ^* is calculated from the left / right braking force steering torque target value Tfx ^* based on the relationship of the following equation (2). To do.
Here, “sin” is a scrub radius in the inner ring, and “sout” is a scrub radius in the outer ring.

As described above, in the fifth embodiment, the required auxiliary steering torque target value depends on the wheel load of the left and right front wheels FL and FR, the lateral force acting on the caster trail and the left and right front wheels FL and FR when turning the left and right front wheels FL and FR. Correct T ^* . Then, the required steering assist torque by the target value T ^* is corrected, it is possible to improve the required steering assist torque target value T ^* setting accuracy of required during steering. Furthermore, by setting the required auxiliary steering torque target value T ^* with high accuracy, the setting accuracy of the left / right braking / driving force steering torque can be improved and set to an appropriate magnitude.
As a result, an increase in thrust of the steering device 4 can be more effectively suppressed while reducing the driver's steering force burden.

In the fifth embodiment, the scrub radii of the left and right front wheels FL and FR necessary for calculating the left / right braking / driving force difference target value Fxgap ^* are set according to the steering angle. That is, the left / right braking / driving force difference target value is changed according to the steering angle and the scrub radius, and the left / right braking / driving force steering torque also varies accordingly.
For this reason, the left / right braking / driving force steering torque can be made to correspond to the scrub radii of the left and right front wheels FL, FR, and an increase in thrust of the steering device 4 can be further effectively suppressed.

  As described above, the effects listed below can be obtained in the steering device according to the fifth embodiment.

(6) Steering angle detection means (steering angle sensor) 8C for detecting the steering angle of the steering means (steering mechanism) 3;
Steering wheel lateral force setting means (step S1J) for setting lateral force acting on the pair of left and right steering wheels (left and right front wheels) FL, FR, or a caster trail during turning on the pair of left and right steering wheels FL, FR Caster rail setting means for setting (step S1H),
The braking / driving force control means (foil-in motor controller) 5 has a steering angle, lateral force acting on the pair of left and right steering wheels FL, FR, or the pair of left and right steering wheels FL, FR. The left and right braking / driving force steering torque is set on the basis of the caster trail at the time of turning.
As a result, in addition to the effects (1) to (5) above, the left / right braking / driving force steering torque can be set according to changes in the vehicle state, and the steering force burden on the driver can be reduced while steering. An increase in thrust of the device 4 can be further effectively suppressed.

(7) Wheel load calculation means (step S1G) for calculating a wheel load acting on the pair of left and right steering wheels (left and right front wheels) FL, FR;
The braking / driving force control means (foil-in motor controller) 5 is configured to set the magnitude of the left / right braking / driving force steering torque based on the wheel load.
As a result, in addition to the effects (1) to (6) above, the left / right braking / driving force steering torque can be set in accordance with changes in the vehicle state, and the steering force burden on the driver is reduced while steering. An increase in thrust of the device 4 can be further effectively suppressed.

(8) Steering angle detecting means (steering angle sensor) 8C for detecting the steering angle of the steering means (steering mechanism) 3;
Scrub radius setting means (step S7A) for setting a scrub radius in the pair of left and right steered wheels (front left and right wheels) FL, FR;
The braking / driving force control means (foil-in motor controller) 5 sets the magnitude of the left / right braking / driving force steering torque based on the magnitude of the steering angle and the scrub radius of the pair of left and right steering wheels FL, FR. It was set as the structure to do.
As a result, in addition to the effects (1) to (7) above, the left / right braking / driving force steering torque can be set according to changes in the vehicle state, and the steering force burden on the driver can be reduced while steering. An increase in thrust of the device 4 can be further effectively suppressed.

  As mentioned above, although the steering device of the present invention has been described based on the first to fifth embodiments, the specific configuration is not limited to these embodiments, and it relates to each claim of the claims. Design changes and additions are allowed without departing from the scope of the invention.

In the third embodiment, the necessary auxiliary steering torque target value T ^* is changed according to the steering angle, the vehicle speed, and the driver steering torque. However, the present invention is not limited to this. For example, the required auxiliary steering torque target value T ^* is changed based on the amount of increase or decrease of the steering angle or the steering speed, and the left / right braking / driving force steering torque is changed according to the changed required auxiliary steering torque target value T ^*. May be set.
Even in this case, it is possible to generate the right / left braking / driving force steering torque having an appropriate magnitude according to the vehicle state, and to appropriately handle the driver's steering force load without using the power steering device 4 having a large thrust. Can be reduced.

  In the above-described embodiment, the left and right front wheels FL and FR serve as both the steering wheel and the driving wheel. However, the steering device of the present invention is applicable to a vehicle having the steering wheel as the front wheel and the driving wheel as the rear wheel. Can be applied.

1 Vehicle 2A Left wheel-in motor (right and left drive wheel independent control means)
2B Right wheel-in motor 3 Steering mechanism (steering means)
3A Steering wheel 3B Steering shaft 3C Rack and pinion 4 Power steering device (auxiliary steering torque generator)
5 Wheel-in motor controller (braking / driving force control means)
6 battery
FL, FR Front left and right wheels (a pair of left and right steering wheels)
RL, RR Left and right rear wheels 8A Accelerator opening sensor 8B Vehicle speed sensor (vehicle speed detection means)
8C Steering angle sensor (steering angle detection means)
8D driver steering torque sensor (driver steering torque detection means)
8E Brake pedal sensor

Claims (8)

Steering means for steering a pair of left and right steering wheels via a steering wheel;
Left and right driving wheel independent control means disposed on the pair of left and right steering wheels and independently applying braking force or driving force to each steering wheel;
Auxiliary steering torque generating means for applying auxiliary steering torque for assisting steering of the steering means;
By controlling the left and right driving wheel independent control means to apply a braking force or a driving force of different magnitude to the pair of left and right steering wheels, it acts in the same direction as the direction of the auxiliary steering torque, Braking / driving force control means for generating left / right braking / driving force steering torque for assisting the auxiliary steering torque;
A steering apparatus comprising: The steering apparatus according to claim 1, wherein
A steering angle detecting means for detecting a steering angle of the steering means;
The steering / braking force control means generates the left / right braking / driving force steering torque when the steering angle is equal to or greater than a predetermined value. In the steering device according to claim 1 or 2,
Steering angle detection means for detecting a steering angle of the steering means;
Vehicle speed detection means for detecting the vehicle speed;
A driver steering torque detecting means for detecting steering torque by the driver, and at least one of
The braking / driving force control means sets the magnitude of the left / right braking / driving force steering torque based on at least one of the magnitude of the steering angle, the amount of increase / decrease of the steering angle, the steering speed, the vehicle speed, and the driver steering torque. A steering device characterized by that. The steering apparatus according to any one of claims 1 to 3,
Steering angle detection means for detecting a steering angle of the steering means;
Vehicle speed detection means for detecting the vehicle speed,
The braking / driving force control means, when the vehicle speed is less than a preset first threshold value, when the steering means is steered in the turning direction rather than the left and right driving force steering torque when the steering means is steered in the turning back direction. A steering device characterized by increasing the left and right driving force steering torque. The steering apparatus according to claim 4, wherein
The braking / driving force control means steers the steering means in the turning direction when the vehicle speed is greater than or equal to the first threshold value and less than a preset second threshold value and the steering angle of the steering means is greater than or equal to a predetermined value. A steering device characterized in that the left and right driving force steering torque when the steering means is steered in the return direction is greater than the left and right driving force steering torque. The steering apparatus according to any one of claims 1 to 5,
Steering angle detection means for detecting a steering angle of the steering means;
Steering wheel lateral force setting means for setting a lateral force acting on the pair of left and right steering wheels, or a caster trail setting means for setting a caster trail at the time of turning in the pair of left and right steering wheels,
The braking / driving force control means is configured to control the left / right braking / driving force based on a steering angle and a lateral force acting on the pair of left and right steering wheels, or on the caster trail when the pair of left and right steering wheels are steered. A steering device characterized by setting a magnitude of steering torque. In the steering device according to any one of claims 1 to 6,
A wheel load calculating means for calculating a wheel load acting on the pair of left and right steering wheels;
The steering device according to claim 1, wherein the braking / driving force control means sets a magnitude of the left / right braking / driving force steering torque based on the wheel load. In the vehicle braking / driving force control means according to any one of claims 1 to 7,
Steering angle detection means for detecting a steering angle of the steering means;
Scrub radius setting means for setting a scrub radius in the pair of left and right steering wheels,
The steering device according to claim 1, wherein the braking / driving force control means sets the magnitude of the left / right braking / driving force steering torque based on a size of a steering angle and a scrub radius of the pair of left and right steering wheels.