JP2007118863A - Steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device capable of performing adequate steering support by suppressing a sense of incongruity on a driver when detecting an emergency condition of a vehicle. <P>SOLUTION: The steering device 10 is provided with a steering support quantity increasing means 14 for increasing the steering support quantity to the steering operation by a driver when detecting an emergency condition of the vehicle. In this steering device 10, the steering support quantity increasing means 14 increases the steering support quantity based on the steering characteristic of the driver. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a steering apparatus including a steering assist amount increasing means for increasing a steering assist amount for a driver's steering operation when an emergency state of a vehicle is detected.

Conventionally, as a steering device that assists the driver's steering operation and reduces the burden on the driver, there is one disclosed in Patent Document 1, for example. In this steering device, when an obstacle is found ahead in the traveling direction, the magnitude of the auxiliary steering torque is increased according to the collision margin time to assist the steering operation.
JP 2000-43741 A

  However, although the steering assistance by the conventional steering device described above is useful for a driver who cannot give sufficient steering force, the driver who can give sufficient steering force feels uncomfortable due to a change in steering feeling. There is a risk of giving.

  The present invention has been made in view of the above-described circumstances, and provides a steering device capable of performing appropriate steering support while suppressing an uncomfortable feeling given to a driver when an emergency state of a vehicle is detected. Objective.

  A steering apparatus according to the present invention is a steering apparatus including a steering support amount increasing means for increasing a steering support amount for a driver's steering operation when an emergency state of a vehicle is detected. The steering assist amount is increased based on the steering characteristics of the driver.

  In this steering device, since the steering support amount is increased based on the steering characteristics of the driver, the steering support amount can be increased according to the skill of the steering, and appropriate discomfort given to the driver is suppressed and appropriate steering support is performed. Can do.

  The steering device preferably includes a pedaling force detecting unit that detects a pedaling force of a brake pedal of the driver, and the steering assist amount increasing unit preferably estimates a steering characteristic based on a detected value of the pedaling force. A driver with a weak pedal force of the brake pedal is likely to be unable to perform a sufficient steering operation, and the steering characteristic can be estimated by detecting the pedal force of the brake pedal in this way.

  Preferably, the steering device includes a depression speed detection unit that detects a depression speed of the brake pedal of the driver, and the steering assist amount increase unit estimates the steering characteristics based on the detected value of the depression speed. A driver with a slow depression speed of the brake pedal is likely not to be able to perform a sufficient steering operation, and the steering characteristics can be estimated by detecting the depression speed of the brake pedal in this way.

  Preferably, the steering assist amount increasing means increases the steering assist amount when it is determined that the steering characteristic is inferior, and stops increasing the steering assist amount when it is determined that the steering characteristic is excellent. In this way, it is possible to increase the steering support amount for a driver with poor steering characteristics and provide appropriate steering support, while for the driver with excellent steering characteristics, stop increasing the steering support amount. A sense of incongruity can be suppressed.

  The detected value is preferably a value detected when an emergency state of the vehicle is detected. In this way, the steering characteristics when the vehicle is in an emergency state can be accurately reflected, and the steering operation can be more appropriately supported.

  A steering device according to the present invention is a steering device including a steering assist amount increasing means for increasing a steering assist amount for a driver's steering operation when an emergency state of a vehicle is detected, and detects a steering speed of the driver. Steering speed detection means is provided, and the steering assistance amount increasing means increases the steering assistance amount so as to be the target value when the detected value of the steering speed is lower than the target value. In this way, by appropriately setting the target value, it is possible to suppress the uncomfortable feeling given to the driver and appropriately assist the steering.

  The steering assist amount preferably includes a wheel turning amount with respect to a driver's steering operation. The steering assist amount preferably includes the amount of auxiliary steering torque with respect to the driver's steering operation.

  ADVANTAGE OF THE INVENTION According to this invention, when the emergency state of a vehicle is detected, the discomfort given to a driver can be suppressed and appropriate steering assistance can be performed.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a system configuration diagram of a vehicle steering apparatus 10 according to the present embodiment. The steering apparatus 10 includes an emergency determination electronic control unit (hereinafter referred to as emergency determination ECU) 12, a steering electronic control unit (hereinafter referred to as steer ECU) 14, and a brake electronic control unit (hereinafter referred to as brake ECU) 16. It has. The steering device 10 is controlled by the emergency determination ECU 12, the steering ECU (steering assistance amount increasing means) 14, and the brake ECU 16, so that an assist force (steering assistance amount) corresponding to the vehicle speed is obtained when the driver performs a steering operation. The front wheels FL and FR are steered while giving.

The steering device 10 includes a steering wheel 18. A steering shaft 20 is fixed to the steering wheel 18. The steering shaft 20 is configured to be able to rotate as the steering wheel 18 rotates. A steering angle sensor 22 is disposed on the steering shaft 20. The steering angle sensor 22 outputs a signal corresponding to the steering angle θ of the steering wheel 18. The output signal of the steering angle sensor 22 is supplied to the steer ECU 14. The steer ECU 14 detects the steering angle θ and the steering speed V _θ of the steering wheel 18 based on the output signal of the steering angle sensor 22. Thus, the steer ECU 14 and the steering angle sensor 22 constitute a steering speed detecting means.

  Further, the steering device 10 includes a gear ratio variable mechanism 24. The gear ratio variable mechanism 24 changes the steered amount (gear ratio) of the front wheels FL and FR with respect to the driver's steering operation according to a command signal from the steering ECU 14.

  A steering gear box 26 is connected to the output side of the gear ratio variable mechanism 24. The steering gear box 26 is configured by a rack and pinion method, and has a function of converting the rotational movement of the pinion accompanying the rotation of the steering shaft 20 into a linear movement in the axial direction of the rack bar 28. A knuckle arm 30 is connected to both ends of the rack bar 28 via tie rods. The left and right front wheels FL and FR are fixed to the knuckle arm 30. The front wheels FL and FR are steered when the rack bar 28 is displaced in the vehicle width direction.

  In the above configuration, when the steering wheel 18 is operated, the steering shaft 20 rotates, and the pinion rotates with the rotation. A frictional force acts between the pinion of the steering gear box 26 and the rack gear. When the pinion rotates with a torque exceeding the frictional force, the rack bar 28 is displaced in the vehicle width direction, thereby turning the front wheels FL and FR. When the steering wheel 18 is rotated in the direction opposite to the above, the rack bar 28 is displaced in the direction opposite to the vehicle width direction, whereby the front wheels FL and FR are steered in the direction opposite to the above. Therefore, according to the steering device 10 of the present embodiment, the driver applies the steering torque to the steering wheel 18 to a certain extent, so that the front wheels FL and FR are moved in the left-right direction according to the gear ratio set by the gear ratio variable mechanism 24. The vehicle can be turned to turn the vehicle.

  A motor 32 provided in the gear box 26 is connected to the steer ECU 14. The motor 32 generates auxiliary steering torque that assists the steering torque of the driver, and assists the displacement of the rack bar 28 in the vehicle width direction.

  By the way, when the vehicle travels at a high speed and a steering assist amount equivalent to that at the time of low speed travel is given, the rack bar 28 is greatly displaced by a slight operation of the steering wheel 18, and the straight running stability of the vehicle is remarkably increased. There is a risk of damage. For this reason, it is preferable that the steering assist amount given in accordance with the operation of the steering wheel 18 is smaller as the vehicle speed is higher. Therefore, a vehicle speed sensor 34 is connected to the steer ECU 14 in order to detect the vehicle speed.

  A forward obstacle detection sensor 36 and a vehicle state quantity detection sensor 38 are connected to the emergency determination ECU 12. The front obstacle detection sensor 36 transmits and receives signals with a predetermined beam angle spread by rotating a radar antenna extending in a vertical direction to a bumper or the like at the front of the vehicle. The emergency determination ECU 12 performs an appropriate process on the signal supplied from the front obstacle detection sensor 36 to detect an obstacle present in the detection range in front of the vehicle.

  The own vehicle state quantity detection sensor 38 is a vehicle speed sensor that outputs a pulse signal at a cycle according to the vehicle speed V, a yaw rate sensor that outputs a signal according to the rotational angular velocity around the center of gravity of the vehicle, and the steering angle θ of the steering wheel 18. A steering angle sensor that outputs a signal corresponding to the stroke, and a stroke sensor that outputs a signal corresponding to the stroke S of the brake pedal. The emergency determination ECU 12 detects the vehicle speed V, the yaw rate γ, the steering angle θ, and the pedal stroke S based on the signal output from the vehicle state quantity detection sensor 38.

  A stroke sensor 40 is connected to the brake ECU 16. The stroke sensor 40 outputs an electric signal corresponding to the stroke S of the brake pedal. The output signal of the stroke sensor 40 is supplied to the brake ECU 16. The brake ECU 16 controls a brake device (not shown) based on the output signal of the stroke sensor 40 to generate a braking force according to the operation amount of the brake pedal.

  Next, steering assistance control by the steering apparatus 10 having the above-described configuration will be described with reference to the flowchart of FIG.

First, in step S1, the emergency determination ECU 12 determines whether or not the vehicle is in an emergency state. That is, the emergency determination ECU 12 calculates the relative distance L between the host vehicle and the front obstacle from the output signal of the front obstacle detection sensor 36, and based on the relative distance L and the output signal of the host vehicle state quantity detection sensor 38. The relative speed V _r is calculated from the detected vehicle speed V. Based on the relationship between the relative distance L, the relative speed V _r , and the host vehicle speed V, the possibility of the host vehicle colliding with a front obstacle is calculated.

  If it is determined that there is no possibility of a collision, the steering assist control is terminated while maintaining the steering assist amount without increasing it. On the other hand, if it is determined that there is a possibility of collision, the process proceeds to step S2. In step S <b> 2, the steer ECU 14 determines whether or not there has been a steering operation by the driver based on a signal from the steering angle sensor 22. And when it determines with there being no steering operation, it moves to step S3.

  In step S <b> 3, the steer ECU 14 determines whether or not a brake operation has been performed based on a signal from the brake ECU 16. And when there is no brake operation, steering assistance control is complete | finished in the state maintained as it is, without increasing a steering assistance amount. On the other hand, if there is a brake operation, the process proceeds to step S4.

In step S4, the brake ECU 16 calculates a depression force (stroke amount) F _b and a depression speed (stroke speed) V _b of the driver's brake pedal based on a detection signal from the stroke sensor 40. Thus, the brake ECU 16 and the stroke sensor 40 constitute a stepping force detection means and a stepping speed detection means. Then, the steer ECU 14 estimates the steering characteristics of the driver based on the pedaling force F _b and the depression speed V _b data sent from the brake ECU 16.

In other words, steering ECU14 determines whether pedal force _{F b} is less than a predetermined reference value _{F c,} and depression speed _{V b} is whether below a predetermined reference value _{V c.} In general, a general driver who cannot perform a brake operation well is likely to be unable to perform a sufficient steering operation in an emergency. As described above, since there is a high correlation between superiority and inferiority of the brake operation and superiority of the steering operation, in this embodiment, the steering characteristics of the driver are estimated based on the brake operation. Here, the predetermined reference values F _c and V _c are determined as follows. First, the general driver and professional driver, in advance acquires the statistic of pedal force F _b and depression speed V _b of the brake pedal in an emergency. Then, based on the acquired data, reference values F _c and V _c are determined as threshold values for determining that the brake operation is performed by a general driver.

Based on the predetermined reference values F _c and V _c determined in this way, the steer ECU 14 determines that the steering characteristic is good when both the stepping force F _b and the stepping speed V _b are equal to or higher than the reference values F _c and V _c. It determines with it being excellent, and complete | finishes steering assistance control in the state maintained as it is, without increasing a steering assistance amount. On the other hand, when at least one of pedal force F _b and depression speed V _b is less than the reference value F _c, V _c, it is determined that the steering characteristic is inferior, thereby increasing the steering assist amount goes to step S5.

  Here, the amount of increase in the steering assist amount is set as follows. That is, as shown in FIG. 3, for a general driver and a professional driver, a plurality of steering characteristics are obtained in advance according to the vehicle speed. In the steering characteristics of the professional driver indicated by the solid line L1, the steering speed at the initial stage of steering is much faster and the steering waveform rises smoothly and quickly than the steering characteristics of the general driver indicated by the broken line L2. Therefore, there is a margin for steering when turning back, and the vehicle behavior is stabilized. On the other hand, in the steering operation by a general driver, since the steering at the time of turning must be accelerated, the possibility that the vehicle becomes very unstable and spins increases.

  Therefore, if it is determined YES in step S4 and it is determined that the steering characteristics of the driver are inferior, the steering assist amount is set so that the initial steering characteristics L1 of the professional driver is obtained with reference to the steering characteristics L2 of the general driver. Prepare by adjusting the gear ratio and the amount of auxiliary steering torque. Thereby, when steering operation is actually performed, initial steering close to the steering characteristics of the professional driver is obtained. After setting the initial value in this way, the gear ratio and the amount of auxiliary steering torque are adjusted by feedback control so that the steering waveform (time series data) of the professional driver is obtained.

On the other hand, when it determines with there being steering operation in step S2, it moves to step S6. The steering speed V _s is whether lower than the target value V _g is determined. The target value V _g, and steering speed in the steering characteristics of a professional driver shown in FIG. When the steering speed V _s is equal to or greater than the target value V _g with fast, understeering occurs, as long as the vehicle stability control (VSC) is not a situation of operation, and it ends the steering assist control. On the other hand, when the steering speed V _s is lower than the target value V _g , the gear ratio is lowered to the target steering speed V _g by feedback control, and the gear ratio is further lowered so that the steering does not become heavy. In addition, the amount of auxiliary steering torque is increased.

  Thus, in the steering apparatus 10 according to the present embodiment, when there is no steering operation and there is a brake operation, the steering characteristics are estimated based on the depression force and the depression speed of the driver's brake pedal. Then, when it is determined that the steering characteristics are inferior, the steering assist amount is increased, and when it is determined that the steering characteristics are excellent, the increase of the steering assist amount is stopped. As a result, it is possible to increase the steering support amount for a driver with poor steering characteristics and provide appropriate steering support, while for a driver with excellent steering characteristics, stop increasing the steering support amount to feel uncomfortable. Can be suppressed.

  In particular, since the detected values of the pedaling force and the stepping speed are values detected when an emergency state of the vehicle is detected, the steering characteristics when the vehicle is in an emergency state can be accurately reflected, and the steering operation can be performed. More appropriate support can be provided.

  Further, in the steering device according to the present embodiment, when the steering operation is performed, when the detected value of the steering speed is lower than the target value, the steering assist amount is increased so as to become the target value by feedback control. Steering assistance can be performed according to the skill of the driver, and steering assistance can be appropriately performed while suppressing a sense of discomfort given to the driver.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the above embodiment, so-called on / off control is performed in which the steering characteristics are estimated based on the brake operation characteristics of the driver, and it is determined whether to increase the steering assist amount based on the estimated steering characteristics. The determination in step S4 may be omitted, and the steering assist amount may be set according to the actually detected pedaling force and stepping speed. That is, as shown in FIG. 4A, the assist gain (α) is set for the pedaling force, and as shown in FIG. 4B, the assist gain (β) is set for the stepping speed. A gear ratio is set for the product of the assist gain (α) and the assist gain (β) as shown in FIG. Further, a steering assist torque amount is set according to the set gear ratio. In this way, since the product of the assist gain (α) and the assist gain (β) of the driver reflects the operation characteristics of the brake, the steering assist amount can be set according to the brake operation characteristics of the driver. . Note that the gear ratio may be set based only on the stepping force, or the gear ratio may be set based only on the stepping speed.

  Moreover, although the case where the state where the own vehicle collides with an obstacle ahead is recognized as an emergency state is not limited to this, for example, the state where the vehicle departs from a predetermined traveling lane is recognized as an emergency state. It is good.

  In the above embodiment, the driver's steering characteristic is estimated based on the brake operation characteristic. However, the steering characteristic may be set by the driver by the switch means, or the steering characteristic may be actually detected. Good.

1 is a system configuration diagram of a vehicle steering apparatus according to an embodiment. It is a flowchart which shows the flow of the steering assistance control by the steering apparatus which concerns on embodiment. It is a figure which shows the steering characteristic of a professional driver and a general driver. It is a figure for demonstrating the method to set a gear ratio based on the depression force and depression speed of a brake pedal.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Steering device, 12 ... Emergency determination ECU, 14 ... Steer ECU, 16 ... Brake ECU, 22 ... Steering angle sensor, 24 ... Gear ratio variable mechanism, 32 ... Motor, 40 ... Stroke sensor.

Claims (8)

A steering device comprising a steering assistance amount increasing means for increasing a steering assistance amount for a driver's steering operation when an emergency state of a vehicle is detected,
The steering assist amount increasing means increases the steering assist amount based on a steering characteristic of a driver. A pedal force detection means for detecting the pedal force of the brake pedal of the driver;
The steering apparatus according to claim 1, wherein the steering assist amount increasing unit estimates the steering characteristic based on a detected value of the pedal effort. Provided with a depression speed detection means for detecting the depression speed of the brake pedal of the driver,
The steering apparatus according to claim 1, wherein the steering assist amount increasing unit estimates the steering characteristics based on a detected value of the stepping speed.   The steering assist amount increasing means increases the steering assist amount when it is determined that the steering characteristic is inferior, and stops increasing the steering assist amount when it is determined that the steering characteristic is excellent. The steering apparatus according to claim 2 or 3.   The steering device according to any one of claims 2 to 4, wherein the detected value is a value detected when an emergency state of the vehicle is detected. A steering device comprising a steering assistance amount increasing means for increasing a steering assistance amount for a driver's steering operation when an emergency state of a vehicle is detected,
A steering speed detecting means for detecting the steering speed of the driver;
The steering assisting amount increasing means increases the steering assisting amount so as to be the target value when the detected value of the steering speed is lower than the target value.   The steering apparatus according to claim 1, wherein the steering assist amount includes a steering amount of a wheel with respect to a driver's steering operation.   The steering apparatus according to claim 1, wherein the steering assist amount includes a torque amount of an auxiliary steering torque with respect to a driver's steering operation.

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