JP2005059704A - Steering device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device for vehicles capable of reducing excessive power consumption attributable to twist of a tire ground contact plane or the like. <P>SOLUTION: The steering device for vehicles comprises a reaction force actuator 2 to give the steering reaction device to a steering wheel 1 which is not mechanically connected to a turning actuator 8 to turn a turning wheel 6, a steering angle sensor 4 to detect the steering angle of the steering wheel 1, a vehicle speed sensor 12 to detect the vehicle speed, and a control device 11 which sets the control quantity of the reaction force actuator 2 and the turning actuator 8 based on the detected steering angle and vehicle speed and controls the reaction force actuator 2 and the turning actuator 8. The control device 11 sets the control quantity of the reaction force actuator 2 based on the control quantity to be output to the turning actuator 8. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention belongs to the technical field of a vehicle steering apparatus that employs a steer-by-wire system.

As this type of prior art, for example, when steering at extremely low speeds, a steering reaction force is generated in a direction opposite to the steering direction when the steering speed is high, and a steering reaction force is generated when the steering speed is low. It is known that the steering feeling is improved by canceling the occurrence of (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2003-2224

  However, in the above prior art, when a drag force such as a twist of the tire ground contact surface is generated when the steered wheels are steered at the time of stationary or steering at an extremely low speed, the target steered angle Even if does not change, the steering actuator continues to generate a force to counter this drag. Therefore, even if the steering means is not steered, the drive current continues to be output to the steered actuator, which may cause a loss of power consumption and a decrease in function of the steered actuator.

  The present invention has been made paying attention to the above-described problem, and an object of the present invention is to provide a vehicle steering apparatus that can reduce excessive power consumption caused by twisting of a tire contact surface.

  In order to achieve the above object, the present invention sets a control amount of the reaction force actuator based on the detected steering angle and vehicle speed, controls the reaction force actuator, and detects the detected steering angle and vehicle speed. A steering control unit that sets a control amount of the steering actuator based on the steering control unit and controls the steering actuator, wherein the steering control unit outputs the steering control unit to the steering actuator. The control amount of the reaction force actuator is set based on the controlled amount.

  In the present invention, the reaction force actuator is driven according to the control amount output from the steering control means, and the steering means generates a steering reaction force. That is, while the control amount is being output to the steering actuator, a steering reaction force is generated by the reaction force actuator. Therefore, when the driver removes his / her hand from the steering means, the steering means stops when the control amount is not output from the steering control means to the steering actuator, that is, at a position where the current consumption of the steering actuator becomes almost zero. Therefore, it is possible to reduce excessive power consumption caused by twisting of the tire ground contact surface.

  The best mode for carrying out the vehicle steering system of the present invention will be described below based on the first and second embodiments.

First, the configuration will be described.
FIG. 1 is a configuration diagram of a vehicle steering apparatus according to a first embodiment.
The vehicle steering apparatus according to the first embodiment includes a steering wheel (steering means) 1, a reaction force actuator 2, a reaction force control amount detection sensor 3, a steering angle sensor (steering angle detection means) 4, a steering torque sensor ( (Steering torque detection means) 5, steering actuator 8, steering control amount detection sensor (steering control amount detection means) 9, steering angle sensor 10, and control device (steering control means, steering control means) 11 and a vehicle speed sensor (vehicle speed detection means) 12.

  The steering torque sensor 5 detects a steering torque generated between the steering wheel 1 and the reaction force actuator 2. The steering angle sensor 4 detects the steering angle of the steering wheel 1. The reaction force control amount detection sensor 3 detects the control amount of the reaction force actuator 2.

  The turning control amount detection sensor 9 detects the control amount of the turning actuator 8. The steered angle sensor 10 detects the steered angle of the steered wheels 6. The vehicle speed sensor 12 detects the speed of the vehicle. The outputs of these sensors are input to the control device 11.

  The control device 11 calculates a control amount of the reaction force actuator 2 that generates a steering reaction force in the steering wheel 1 and a control amount of the steering actuator 8 that drives the steering gear 7 based on the output of each sensor. . The reaction force actuator 2 outputs a steering reaction force to the steering wheel 1 in accordance with a control amount supplied from the control device 11. Similarly, the steered actuator 8 changes the steered angle of the steered wheels 6 according to the control amount supplied from the control device 11.

  With the above configuration, the vehicle steering apparatus according to the first embodiment realizes a so-called steer-by-wire function that can arbitrarily change the characteristic of the turning angle with respect to the driver's steering input.

FIG. 2 is a control block diagram of the vehicle steering apparatus.
The control device 11 includes a reaction force calculation unit 11a, a turning angle calculation unit 11b, a reaction force driver 11c, and a turning driver 11d.

  The outputs of the steering angle sensor 4 and the vehicle speed sensor 12 are input to the reaction force calculation unit 11a and the turning angle calculation unit 11b. The output of the reaction force calculation unit 11a is output to the reaction force driver 11d, and the reaction force driver 11c outputs a physical quantity such as a current value for driving the reaction force actuator 2.

  The reaction force control amount detection sensor 3 detects a control amount such as a current value output from the reaction force driver 11c to the reaction force actuator 2, and feeds it back to the reaction force driver 11c. The output of the steering torque sensor 5 is input to the reaction force calculation unit 11a. The output of the turning angle calculation unit 11b is output to the turning driver 11d, and the turning driver 11d outputs a physical quantity such as a current value for driving the turning actuator 8. The output of the steering driver 11d is also input to the reaction force calculation unit 11a.

  The steered control amount detection sensor 9 detects a control amount such as an electric current value output from the steered driver 11d to the steered actuator 8, and feeds back to the steered driver 11d. The output of the turning angle sensor 10 is input to the turning angle calculation unit 11b.

  In the reaction force calculation unit 11a, when the vehicle speed detected by the vehicle speed sensor 12 is equal to or lower than a predetermined value (corresponding to the first set vehicle speed), for example, steering proportional to the control amount output by the steering driver 11d is performed. A steering reaction force according to the control amount of the steering actuator 8 such as a reaction force is generated.

Next, the operation will be described.
[Steering reaction force calculation control processing]
FIG. 3 is a flowchart showing the flow of the steering reaction force calculation control process performed in the reaction force calculation unit 11a of the control device 11, and each step will be described below.

  In step S300, the present system is activated with the vehicle's ignition key switch turned on as a trigger, and the process proceeds to step S301.

  In step S301, the vehicle speed V is input from the vehicle speed sensor 12, and the process proceeds to step S302.

  In step S302, it is determined whether or not the vehicle speed V is equal to or lower than a predetermined value (first set vehicle speed; for example, 2 km / h). If YES, the process proceeds to step S303, and if NO, the process proceeds to S305.

In step S303, the command value to the steering actuator 8 output from the steering driver 11d is input, and the process proceeds to step S304.
In this step, for example, when the steering actuator 8 has a rotary motor structure, a steering reaction force proportional to the drive current is output, so the command current i calculated by the steering driver 11d is input.

In step S304, a steering reaction force T corresponding to the command current i calculated in the steered driver 11d is calculated, and the process proceeds to step S301.
In this case, for example, a proportional output such as T = i × k (k is a proportional constant) may be used, or steering may be expressed by a relational expression such that T = 0 when i = 0 and monotonically increasing with respect to i. You may make it output reaction force.

  In step S305, the steering angle θ of the steering wheel 1 steered by the driver is input from the steering angle sensor 4, and the process proceeds to step S306.

In step S306, a steering reaction force T corresponding to the vehicle speed V and the steering angle θ of the steering wheel 1 is calculated, and the process proceeds to step S301.
Here, a map of the steering reaction force given from the values of the vehicle speed V and the steering angle θ may be stored in advance, and the value on the map may be output, or the equation of motion of the vehicle and the steering gear ratio It may be calculated from vehicle-specific parameters such as (steering angle θ / steering angle δ) using vehicle speed V and steering angle θ.

[Steering reaction force calculation control action]
When the vehicle is stopped or traveling at an extremely low speed, the flow proceeds from step S300 to step S301 to step S302 to step S303 to step S304 in the flowchart of FIG. That is, in step S302, it is determined that the vehicle speed V is equal to or lower than a predetermined value. In step S303, a command output current i output from the steering driver 11d to the steering actuator 8 is input. In step S304, the command output current i A steering reaction force T corresponding to i is output.

  When the vehicle is traveling at a medium speed or a high speed, the flow proceeds from step S300 to step S301 to step S302 to step S305 to step S306 in the flowchart of FIG. That is, in step S302, it is determined that the vehicle speed V is greater than a predetermined value. In step S305, the steering angle θ of the steering wheel 1 is input. In step S306, the steering reaction force T corresponding to the steering angle θ and the vehicle speed V is input. Is output.

As described above, in the vehicle steering system of the first embodiment,
When the steering wheel 1 is steered and the hand is released, the steering wheel 1 stops almost at the steering angle.
・ Equivalent steering reaction force is generated when steering from left or right from any steering angle position.
When the steered wheel 6 starts to steer, a constant steering reaction force is generated regardless of the steering angle.
The above control specifications can be satisfied, and a good steering feeling can be obtained.

  Further, when the steering actuator 8 is driven even if the steering wheel 1 is not steered due to twisting of the steered wheels 6 or the like, the power consumption of the steering actuator 8 when the hand is released from the steering wheel 1. Since the steering wheel 1 is stopped at a position where the torque becomes almost zero, excessive power consumption caused by twisting of the tire ground contact surface of the steered wheels 6 can be reduced during stationary driving or extremely low speed steering.

  Further, since the reaction force calculation unit 11a calculates a steering reaction force T proportional to the control amount output from the steering driver 11d to the steering actuator 8, the steering force gradually decreases as the vehicle moves away from the straight steering angle. The force is increased, and the steering wheel 1 is easily returned to the steering angle at which the vehicle goes straight.

Next, Example 2 will be described.
In the first embodiment, the control amount of the reaction force actuator 2 is calculated based on the control amount output from the steering driver 11d to the steering actuator 8, whereas in the second embodiment, the control amount is output to the steering actuator 8. The difference is that the control amount of the reaction force actuator 2 is calculated based on the control amount.

  That is, in the first embodiment, the control amount of the reaction force actuator 2 is set based on the control amount of the steering actuator 8 in the same control cycle. However, in the second embodiment, the control of the steering actuator 8 before one control cycle is performed. Based on the amount, the control amount of the reaction force actuator 2 is set.

FIG. 4 is a control block diagram of the vehicle steering apparatus.
The outputs of the steering angle sensor 4 and the vehicle speed sensor 12 are input to the reaction force calculation unit 11a and the turning angle calculation unit 11b. The output of the reaction force calculation unit 11a is output to the reaction force driver 11d, and the reaction force driver 11c outputs a physical quantity such as a current value for driving the reaction force actuator 2.

  The reaction force control amount detection sensor 3 detects a control amount such as a current value output from the reaction force driver 11c to the reaction force actuator 2, and feeds it back to the reaction force driver 11c. The output of the steering torque sensor 5 is input to the reaction force calculation unit 11a. The output of the turning angle calculation unit 11b is output to the turning driver 11d, and the turning driver 11d outputs a physical quantity such as a current value for driving the turning actuator 8. The steered control amount detection sensor 9 detects a control amount such as a current value output from the steered driver 11d and feeds it back to the steered driver 11d. Further, the detection value of the turning control amount detection sensor 9 is also input to the reaction force calculation unit 11a.

  The output of the turning angle sensor 4 is input to the turning angle calculation unit 11b. In the reaction force calculation unit 11a, when the vehicle speed is equal to or lower than a predetermined value, for example, the steering reaction force according to the detected value of the turning control amount detection sensor 9 such as a steering reaction force proportional to the output value of the turning driver 11d. Generate power.

Next, the operation will be described.
[Steering reaction force calculation control processing]
FIG. 5 is a flowchart showing the flow of the steering reaction force calculation control process performed in the reaction force calculation unit 11a of the control device 11, and each step will be described below.

  In step S500, the present system is activated with a vehicle ignition key switch turned on as a trigger, and the process proceeds to step S500.

  In step S501, the detection value of the turning control amount detection sensor 9 is input, and the process proceeds to step S502. For example, according to the example of the first embodiment, a detection value of a current sensor installed in an output harness to the steering actuator 8 is used.

  In step S502, the same processing as in S304 of FIG. 3 is executed to calculate the steering reaction force T1 (corresponding to the extremely low speed region reaction force actuator control amount), and the process proceeds to step S503.

  In step S503, the vehicle speed V is input from the vehicle speed sensor 12, and the steering angle θ of the steering wheel 1 is input from the steering angle sensor 4, and the process proceeds to step S504.

  In step S504, processing similar to that in S306 in FIG. 3 is executed to calculate a steering reaction force T2 (corresponding to a medium-speed region reaction force actuator control amount), and the process proceeds to step S505.

In step S505, the steering reaction force T is calculated from the following equation (1) according to the vehicle speed V, and the process proceeds to step S501.
T = k ₁ × T1 + k ₂ × T2 (1)
Here, k ₁ and k ₂ are gains of the steering reaction forces T1 and T2 corresponding to the vehicle speed V.

As shown in FIG. 6 (a), the gain k ₁ of T1, the vehicle speed zero to the first set speed V1 1, gradually decreases from the first set speed V1 to the second set speed V2, the second set It is set to zero when the vehicle speed is V2 or higher.

On the other hand, as shown in FIG. 6 (b), the gain k ₂ of T2, the vehicle speed zero to the first set speed V1 zero, gradually increases from the first set speed V1 to the second set speed V2, the It is set to 1 when the vehicle speed is V2 or higher.

[Steering reaction force calculation control action]
When the vehicle is stopped or traveling at an extremely low speed, T1 is output as the steering reaction force T in step S505 of FIG. If the vehicle is traveling at a medium speed or a high speed, T2 is output as the steering reaction force T in step S505 in FIG.

When traveling in a vehicle speed range between the extremely low speed range and the medium speed range, k ₁ × T1 + k ₂ × T2 is output as the steering reaction force T in step S505 of FIG. That is, as the vehicle speed V increases, the distribution ratio of T1 to the steering torque T gradually becomes smaller than the distribution ratio of T2.

  As described above, in the vehicle steering system according to the second embodiment, when traveling in a vehicle speed range between an extremely low speed and a medium speed, the T1 with respect to the steering reaction force T increases as the vehicle speed V increases. Since the distribution ratio is gradually made smaller than the distribution ratio of T2, the steering reaction force T can be shifted while smoothly changing from T1 to T2 even if the vehicle speed region changes.

Also, when stopped or other than extremely low speed,
At any steering angle, a steering reaction force is generated so that when the driver releases his hand from the steering wheel 1, the vehicle returns to the steering angle at which the vehicle goes straight.
The steering reaction force for steering away from the steering angle where the vehicle goes straight is large, but the steering reaction force for returning to the steering angle where the vehicle goes straight is small.
-The steering reaction force gradually increases as the vehicle moves away from the straight steering angle.
The above control specifications can be satisfied, and a good steering feeling can be obtained.

(Other examples)
The best mode for carrying out the present invention has been described based on the first and second embodiments. However, the specific configuration of the present invention is not limited to the first and second embodiments. Design changes and the like within a range that does not deviate are also included in the present invention.

  For example, in Examples 1 and 2, steering control means (reaction force calculation unit 11a, reaction force driver 11c) and steering control means (steering angle calculation unit 11b, steering driver 11d) are provided in the control device 11. However, these control means may be provided separately.

1 is a configuration diagram of a vehicle steering device (first embodiment). FIG. FIG. 1 is a control block diagram of a vehicle steering apparatus (first embodiment). 7 is a flowchart illustrating a flow of a steering reaction force calculation control process performed by the control device (Example 1). (Example 2) which is a control block diagram of the steering apparatus for vehicles. 7 is a flowchart showing a flow of a steering reaction force calculation control process performed by the control device (Example 2). FIG. 5 is a characteristic diagram of gains k ₁ and k ₂ of steering reaction forces T1 and T2 with respect to vehicle speed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Reaction force actuator 3 Reaction force control amount detection sensor 4 Steering angle sensor 5 Steering torque sensor 6 Steering wheel 7 Steering gear 8 Steering actuator 9 Steering control amount detection sensor 10 Steering angle sensor 11 Control apparatus 11a Reaction force Calculation unit 11b Steering angle calculation unit 11c Reaction force driver 11d Steering driver 12 Vehicle speed sensor

Claims (7)

Steering means that is not mechanically connected to a steering actuator that steers the steered wheels;
A reaction force actuator that applies a steering reaction force to the steering means;
Steering angle detection means for detecting a steering angle of the steering means;
Vehicle speed detecting means for detecting the own vehicle speed;
A steering control means for setting a control amount of the reaction force actuator based on the detected steering angle and vehicle speed, and controlling the reaction force actuator;
A steering control means for setting a control amount of the steering actuator based on the detected steering angle and vehicle speed, and controlling the steering actuator;
In a vehicle steering apparatus comprising:
The vehicle steering apparatus according to claim 1, wherein the steering control means sets a control amount of the reaction force actuator based on a control amount output from the steering control means to the steering actuator. The vehicle steering apparatus according to claim 1,
A steering torque detecting means for detecting a steering torque input to the steering means is provided;
The steering control means sets the control amount of the reaction force actuator so that the detected steering torque matches the steering reaction force according to the control amount output from the steering control means to the steering actuator. A vehicle steering apparatus. The vehicle steering apparatus according to claim 1 or 2,
The steering control means determines the control amount of the reaction force actuator based on the control amount output from the steering control means to the steering actuator when the detected vehicle speed is equal to or lower than a first preset vehicle speed. A steering apparatus for a vehicle, characterized by being set. Steering means that is not mechanically connected to a steering actuator that steers the steered wheels;
A reaction force actuator that applies a steering reaction force to the steering means;
Steering angle detection means for detecting a steering angle of the steering means;
Vehicle speed detecting means for detecting the own vehicle speed;
A steering control means for setting a control amount of the reaction force actuator based on the detected steering angle and vehicle speed, and controlling the reaction force actuator;
A steering control means for setting a control amount of the steering actuator based on the detected steering angle and vehicle speed, and controlling the steering actuator;
In a vehicle steering apparatus comprising:
A steering control amount detecting means for detecting a control amount of the steering actuator is provided,
The vehicle steering apparatus, wherein the steering control means sets a control amount of the reaction force actuator based on the detected control amount of the steering actuator. The vehicle steering device according to claim 4,
The steering control means sets the control amount of the reaction force actuator so that the detected steering torque coincides with the steering reaction force according to the detected control amount of the steering actuator. Steering device. In the vehicle steering apparatus according to claim 4 or 5,
The steering control means sets the control amount of the reaction force actuator according to the detected control amount of the steering actuator when the detected vehicle speed is equal to or lower than a first set vehicle speed set in advance. A vehicle steering system. The vehicle steering apparatus according to claim 3 or 6, wherein:
The steering control means includes
When the detected vehicle speed is larger than the first set vehicle speed and smaller than the second set vehicle speed larger than the first set vehicle speed, the medium speed range reaction force actuator set based on the detected steering angle and the vehicle speed Set the control amount of the reaction force actuator from the added value of the control amount and the extremely low speed region reaction force actuator control amount set based on the detected control amount of the steering actuator,
As the detected vehicle speed approaches from the first set vehicle speed to the second set vehicle speed, the distribution ratio of the extremely low speed reaction force actuator control amount to the set reaction force actuator control amount is determined from the medium speed region actuator control amount distribution ratio. Further, the vehicle steering apparatus is characterized by being gradually reduced.

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