JPH07186983A - Steering reaction controller - Google Patents

Abstract

PURPOSE:To perform a simulation of steering reaction at a car stopped state and in time of starting from this stopped state by controlling this steering reaction to be imparted to a steering wheel on the basis of frictional force in the case where a car is in a state of being stopped, and also on the basis of compensated steering reaction torque and the frictional force in the case where the car is in a state of being traveled the other way. CONSTITUTION:An actuator 2 imparting a steering reaction is an electric motor, and torque of this motor is controlled by a motor drive circuit 8 according to a reaction command out of a personal computer 11. On the other hand, a friction imparting mechanism of a steering reaction simulator is composed of a flat belt pulley 3 installed in space between a steering wheel and the actuator 2 and a powder brake 4 connected to this flat belt pulley 3. In the case where a car is in a state of being stopped, steering reaction being imparted to the steering wheel 1 is controlled on the basis of frictional force, and in the case where the car is in a state of being traveled, the steering reaction being imparted to the steering wheel 1 is controlled on the basis of the compensated steering reaction torque and the frictional force, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving simulator for simulating the running condition of an automobile in a laboratory, or a vehicle in which a steering wheel and a steering wheel are not directly connected to each other. The present invention relates to a control device for a device that applies a reaction force.

[0002]

2. Description of the Related Art Japanese Patent Application No. 4-8269 discloses a driving simulator for applying a steering reaction force received when a driver steers a steering wheel.
There is No. 8. In this conventional technique, the steering reaction force applied to the driver is calculated based on the steering angle, the vehicle speed and the slip angle to improve the steering feeling. It may not be possible to simulate the steering reaction force when starting.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a steering reaction force received when a driver steers a steering wheel, and a steering reaction force when the vehicle is stopped and when starting from a stopped state. This is to simulate the steering reaction force at low speeds such as.

[0004]

A steering reaction force control device of the present invention includes a steering angle detecting means for detecting a steering angle of a steering wheel, a vehicle speed detecting and calculating means for detecting or calculating a vehicle speed of a vehicle, and a vehicle speed detecting and calculating means. Determination means for determining whether or not the vehicle is stopped based on the vehicle speed, slip angle calculation means for calculating a slip angle of the steered wheels based on the vehicle speed and the steering angle, the steering angle, the vehicle speed and the slip angle And a steering reaction force torque calculating means for increasing the steering reaction force torque as the vehicle speed increases, and a friction force reducing the friction force as the vehicle speed increases, in a low vehicle speed state. And a steering reaction force torque correction means for calculating a corrected steering reaction force torque by weighting the steering reaction force torque based on the slip angle. When the vehicle is in a stopped state, the steering reaction force applied to the steering wheel is controlled based on the frictional force. When the vehicle is in the traveling state, steering based on the corrected steering reaction force torque and the frictional force is performed. A steering reaction force control device characterized by controlling a steering reaction force applied to a wheel.

[0005]

The present invention has the following effects.
In the present invention, first, based on the vehicle speed of the vehicle, it is determined whether or not the vehicle is stopped. When the vehicle is stopped (when the vehicle is stationary), the frictional force imparting means imparts a substantially constant steering reaction force to the steering wheel regardless of the steering angle and the steering angular velocity. The validity of applying such a steering reaction force will be described below. When stationary, the frictional force that acts on the contact surface between the tire and the road surface is large. To do. Therefore, the hydraulic oil is pressurized by the power steering pump to a state close to the maximum set pressure. Further, the frictional force is substantially constant regardless of the steering angle.

Therefore, when the pressure is close to the maximum set pressure, the torsion angle of the torsion bar connected to the steering wheel of the vehicle changes in a narrow region near the maximum value regardless of the steering angle. This means that the steering reaction force during stationary steering is almost constant.

Further, when steering wheel steering is stopped and the hand is released during stationary steering, the steering reaction force disappears accordingly and the steering wheel stops at the steering angle where the hand is released. Further, the steering reaction force in this case is preferably set to be larger than that when the speed is high.

When the vehicle is not stopped, that is, when the vehicle is traveling, first, the slip angle of the steered wheels is calculated based on the steering angle of the steering wheel and the vehicle speed of the vehicle. Next, the steering reaction force is calculated based on the steering angle, the vehicle speed, and the slip angle. Further, the steering reaction force is weighted based on the slip angle to calculate the corrected steering reaction force.

In this case, it is characteristic that the steering reaction torque is increased as the vehicle speed increases and the frictional force is decreased as the vehicle speed increases in a low speed state such as when the vehicle starts from a stopped state. Is. As a result, from the state where the brake torque generated by the frictional force imparting means is larger than the driving torque of the steering reaction force torque imparting means in the vehicle stopped state, the steering reaction force torque is The steering reaction force is continuously connected to a state in which is larger than the brake torque.

[0010]

As described above, during stationary steering,
The steering force of the actual vehicle can be simulated by applying a substantially constant steering reaction force to the steering wheel regardless of the steering angle and the steering angular velocity by the frictional force imparting means. Further, in a low speed state such as when the vehicle is stopped, the steering reaction torque is increased as the vehicle speed increases, and the frictional force is decreased as the vehicle speed increases. A state in which the brake torque generated by the frictional force applying means is larger than the driving torque of the reaction force torque applying means, and the steering reaction force torque is higher than the brake torque due to an increase in the self-aligning torque due to an increase in vehicle speed. The steering reaction force is continuously connected to. Therefore, the present invention can properly simulate the steering reaction force when the vehicle is stopped and the steering reaction force when the vehicle is moving at a low speed such as when starting from the stopped state.

[0011]

EXAMPLES Hereinafter, a case where the present invention is applied to a driving simulator will be described as an example. The structure of this embodiment is shown in FIG.

The driving simulator of this embodiment is
When the driver operates the steering wheel 1, the accelerator 6, and the brake 7, the movement of the vehicle is calculated in the personal computer 11 based on these operation amounts. In this embodiment, the steering reaction force due to the self-aligning torque and the caster effect on the front wheels is obtained, and the steering reaction force is weighted by the function of the slip angle βf of the front wheels, and the simulated steering reaction force equipped in the power steering mechanism of the actual vehicle is obtained. It is characterized by giving to the driver. Actuator 2 for applying this steering reaction force
Is an electric motor, and the torque of this motor is controlled by the motor drive circuit 8 according to a reaction force command from a personal computer.

On the other hand, a flat belt wheel 3 provided between the steering wheel 1 and the actuator 2, and a powder brake 4 connected to the flat belt wheel 3 by the flat belt 5.
A friction applying mechanism of the steering reaction force simulating device is constituted by. The braking force of the powder brake 4 depends on the vehicle speed, the steering angle,
A current calculated by the personal computer 11 according to the steering speed and controlled by the brake drive circuit 9 is applied to the powder brake 4.

The rotation angle of the steering wheel 1, that is, the steering angle is detected by the pulse generator 10 mounted on the electric motor 2. This steering angle is converted into a digital value by the I / O interface attached to the personal computer 11.

The accelerator opening is determined by the accelerator pedal 6
The stroke is detected by a potentiometer in an analog manner, and this signal is converted into a digital value by an analog / digital converter attached to the personal computer 11.

The brake signal is obtained by detecting the stroke of the brake pedal 7 in an analog manner by a potentiometer as in the case of the accelerator opening, and is converted into a digital value by an analog / digital converter of the personal computer 11.

Next, the arithmetic processing performed in the personal computer 11 will be described with reference to FIG. First,
In step 30, the vehicle model for calculating the traveling state of the vehicle from the digitized signals of the driver's driving operation, that is, accelerator, brake, and steering will be briefly described. The acceleration u'in the longitudinal direction of the vehicle is approximately obtained by u '= A * VA-B * VB-C * u2-D * u (1). Where VA: accelerator opening,
VB: Brake stroke, A, B, C and D are appropriately set constants.

First, the steering reaction force when u = 0, that is, when the vehicle is stopped (when the vehicle is stationary) will be described. When the vehicle is stopped (when stationary), the powder brake 4 applies a substantially constant steering reaction force to the steering wheel regardless of the steering angle and the steering angular velocity. The validity of applying a substantially constant steering reaction force in this way will be described below. When stationary, the frictional force that acts on the contact surface between the tire and the road surface is large. To do. Therefore, the hydraulic oil is pressurized by the power steering pump to a state close to the maximum set pressure. Further, the frictional force is substantially constant regardless of the steering angle.

Therefore, in such a state close to the maximum set pressure, as shown in FIG. 10, the torsion angle of the torsion bar connected to the steering wheel of the vehicle changes in a narrow region near the maximum value regardless of the steering angle. Will be done. This means that the steering reaction force during stationary steering is almost constant. Further, when steering wheel steering is stopped and the hand is released during stationary steering, the steering reaction force disappears accordingly, and the steering wheel stops at the steering angle where the hand is released. As described above, at the time of stationary steering, the powder brake 4 applies a substantially constant steering reaction force to the steering wheel regardless of the steering angle and the steering angular velocity, so that the steering reaction force of the actual vehicle can be simulated. Further, the steering reaction force in this case is preferably set to be larger than that when the speed is high.

Next, a case where u> 0, that is, the vehicle is in a traveling state will be described.

If the vehicle is running, step 3
In 1, the lateral and yaw motions of the vehicle are calculated by the following equations based on the vehicle speed and the steering angle obtained by the equation (1).

[0022]

[Equation 1]

Here, m: vehicle weight β: vehicle side slip angle r: vehicle yaw rate kf: front wheel cornering power kr: rear wheel cornering power lf: distance from front wheel to vehicle center of gravity lr: rear wheel to vehicle Distance to center of gravity θh: Steering angle G: Steering system gear ratio (steering wheel angle / front wheel actual steering angle) I: Vehicle yaw moment of inertia

Further, in step 32, (1),
The slip angle βf of the front wheels is calculated by the following equation from the sideslip angle β of the vehicle obtained by solving the simultaneous differential equations of (2) and (3), the yaw rate r, and the detected steering angle θh. βf = β + (lf / u) r−θh / G (4)

In step 33, the self-aligning torque M of the front wheels can be approximated by the following equation in the range where the side slip angle of the front wheels is small. M = ξkf βf (5) where ξ is a pneumatic trail.

Therefore, the running condition of the vehicle is obtained from the signals of accelerator, brake, and steering by the equations (1) to (3), and the self-aligning torque for the front wheels is then obtained by the equations (4) and (5). Desired.

Further, in steps 35, 36 and 37, the torque MC due to the running resistance due to the caster effect is θ
Until h is │θh │ ≦ GC * G (6), it is calculated by MC = kC (θh / G) (7), and when │θh │> GC * G (8), MC = GC * kC (9) Desired. The formulas (6) to (9) are collectively shown in FIG.

Finally, in step 39, the self-aligning torque M obtained by the equation (5) and the torque MC due to the caster effect obtained by the equation (7) or (9) are added. This added torque is the steering reaction force of a manual steering vehicle that does not have a power steering mechanism.

By the way, as described above, in the power steering system, the assist force acts in accordance with the steering torque of the driver, that is, the steering reaction force in the relation of action and reaction, and the sum of the steering force and the assist force of this driver is obtained. , Balance the force with which the front wheels try to return straight. Therefore, the sum of the self-aligning torque calculated by the formula (5) and the torque due to the caster effect calculated by the formula (7) or (9), that is, a part of the combined torque is applied to the driver as a steering reaction force in the driving simulator. For example, it becomes possible to simulate the power steering mechanism.

This combined torque is a function f of the front wheel slip angle.
By weighting with (βf), the power steering mechanism can be effectively simulated. This function f (βf)
Is, for example, as shown in FIG. That is, f (βf) is approximately 1 in the range where the front wheel slip angle βf is small.
And f (βf) decreases as βf increases. The steering reaction force command thus obtained is given by the following equation. Th * = f (βf) * (M + MC) (10)

By the way, when simulating the steering reaction force of the vehicle speed sensitive type power steering, the steering reaction force command Th * represented by the equation (10) may be weighted using the vehicle speed function g (u). I understand. This function g (u) is as shown in FIG.

In this case, it is characteristic that the function g is used in a low speed state such as when the vehicle starts from a stopped state.
The value of (u) is increased as the vehicle speed increases, and the braking force command TBU described later is decreased as the vehicle speed increases, so that the powder brake 4 of the powder brake 4 is compared with the drive torque of the electric motor 2 in the vehicle stopped state. The steering reaction force is continuously connected from the state where the generated brake torque is large to the state where the steering reaction force torque becomes larger than the brake torque due to the increase in the self-aligning torque due to the increase in the vehicle speed.

The reaction force command Th given to the motor drive circuit 8 for driving the electric motor 2 which is the actuator for applying the steering reaction force in FIG. 1 is given by the following equation. Th = g (u) * f (βf) (M + MC) (11)

The steering reaction force Th obtained by the equation (11) is
The value will be the same when the driver cuts in the steering wheel and when it returns. However, in the case of an actual vehicle, the case where the steering wheel is cut is heavier than the case where the steering wheel is returned. That is, the relationship between the steering angle and the steering reaction force has hysteresis as shown in FIG.

The hysteresis characteristic as shown in FIG. 6 can be created by the friction mechanism provided between the actuator 2 and the steering wheel 1, that is, the powder brake 4, as shown in FIG. If the powder braking force is always constant, the hysteresis width B shown in FIG.
Is constant regardless of the steering angle. However, in an actual vehicle, the width of this hysteresis varies depending on the vehicle speed, the steering angle, and the steering angular velocity.

FIG. 7 shows the braking force command TBU depending on the vehicle speed. In this case, what is characteristic is that the braking force command TBU is made smaller as the vehicle speed increases in a low speed state such as when the vehicle starts from a stopped state. By making the braking force command TBU relatively large with respect to the value of the function g (u), from the state where the brake torque generated by the powder brake 4 is larger than the driving torque of the electric motor 2 in the vehicle stop state, Due to the increase in the self-aligning torque due to the increase in the vehicle speed, the steering reaction force is continuously connected to the state where the steering reaction force torque becomes larger than the brake torque.

For example, when the vehicle is started from the state where the steering wheel is fully turned in stationary steering, the brake torque generated by the powder brake 4 is compared with the drive torque of the electric motor 2 until the vehicle speed reaches several km / h. Is large, the steering wheel maintains the same steering angle even when the driver releases the steering wheel. Further, when the vehicle speed becomes higher than several km / h, the drive torque of the electric motor 2 becomes larger than the brake torque generated by the powder brake 4, so that when the driver holds the steering wheel, the steering wheel is in the neutral position. You will feel the reaction force to return to. Thus, by increasing the value of the function g (u) as the vehicle speed increases and decreasing the braking force command TBU as the vehicle speed increases, a low speed state such as when the vehicle is stopped is started. The steering reaction force at can be appropriately simulated.

FIG. 8 shows a braking force command TBa depending on the steering angle. Further, FIG. 9 shows the braking force command TBV based on the steering angular velocity.

The steering reaction force command Th to the motor drive circuit 8 and the command (TBU + TBa + TBV) to the brake drive circuit 9 described above are calculated by the personal computer 11 shown in FIG. Converted to an analog value by an analog converter. The torque of the electric motor 2 and the braking force of the powder brake 4 are controlled based on this analog signal.

As described above, in this embodiment, the steering reaction force due to the self-aligning torque and the caster effect on the front wheels is obtained, and the steering reaction force is weighted by the function of the slip angle βf of the front wheels to determine the power steering mechanism of the actual vehicle. The equipped simulated steering reaction force can be generated.

In this embodiment, the vehicle speed sensitive power steering is mounted by increasing the steering reaction torque as the vehicle speed increases and decreasing the frictional force as the vehicle speed increases in the low vehicle speed state. In the vehicle, the steering reaction force when the vehicle is stopped and the steering reaction force when the vehicle is moving at a low speed such as when starting from the stopped state can be well simulated. Further, in this embodiment, the powder braking force is determined in consideration of the vehicle speed, the steering angle, and the steering angular velocity, and the hysteresis characteristic of the steering reaction force can be well simulated.

[Brief description of drawings]

FIG. 1 is a diagram showing the overall configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a torque Mc and a steering angle θh associated with traveling resistance due to a caster effect according to an embodiment of the present invention.

FIG. 3 is a self-aligning torque M according to an embodiment of the present invention.
And a flowchart for calculating the torque Mc associated with the running resistance due to the caster effect

FIG. 4 is a diagram showing a function for weighting by a steering wheel slip angle according to an embodiment of the present invention.

FIG. 5 is a diagram showing a function for weighting by vehicle speed when calculating a steering reaction force of a speed-sensitive power steering according to an embodiment of the present invention.

FIG. 6 is a diagram showing hysteresis of steering reaction force according to an embodiment of the present invention.

FIG. 7 is a braking force command T according to a vehicle speed according to the embodiment of the present invention.
diagram representing bu

FIG. 8 is a diagram showing a braking force command Tba according to a steering angle according to an embodiment of the present invention.

FIG. 9 is a diagram showing a braking force command Tbv according to a steering angular velocity according to an embodiment of the present invention.

[Explanation of symbols]

 1 Steering Wheel 2 Electric Motor 3 Flat Belt Vehicle 4 Powder Brake 5 Flat Belt 6 Accelerator 7 Brake 8 Motor Drive Circuit 9 Brake Drive Circuit 10 Pulse Generator 11 Personal Computer

Claims (1)

[Claims] 1. A steering angle detecting means for detecting a steering angle of a steering wheel, a vehicle speed detecting calculating means for detecting or calculating a vehicle speed of a vehicle, and a judging means for judging whether or not the vehicle is stopped based on the vehicle speed. A slip angle calculating means for calculating a slip angle of a steered wheel based on the vehicle speed and the steering angle; and a steering reaction torque calculated based on the steering angle, the vehicle speed and the slip angle, In the low state,
A steering reaction force torque calculating means for increasing the steering reaction force torque as the vehicle speed increases, a friction force calculating means for decreasing the friction force as the vehicle speed increases, and weighting the steering reaction force torque based on the slip angle. And a steering reaction force torque correction means for calculating a corrected steering reaction force torque. When the vehicle is in a stopped state, the steering reaction force applied to the steering wheel is controlled based on the friction force, and the vehicle travels. In the state, the steering reaction force control device controls the steering reaction force applied to the steering wheel based on the corrected steering reaction torque and the frictional force.