JP2007237908A - Vehicle controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle controller for suppressing the attitude change of a vehicle when the vehicle whose braking status is held starts to change its attitude while slipping down a sloping road. <P>SOLUTION: When a braking status is held by braking holding control, and the attitude change of a vehicle slipping down a sloping road is detected (S<SB>8</SB>), the holding of the braking status by the braking holding control is released (S<SB>9</SB>), and a steering wheel (34) is rotated to a steering direction to restore the vehicle to its attitude before its attitude change (S<SB>13</SB>). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle control apparatus that suppresses a change in posture of a vehicle that slides down a slope.

  There is known a brake control device that maintains a braking state by the brake device even when the foot is released from the brake pedal when the vehicle is stopped, and releases the holding state when the accelerator pedal is operated ( Patent Document 1).

  However, when the vehicle is stopped on a frozen slope or a steep slope that is not paved, if the braking state is maintained by this brake control device, the attitude of the vehicle will change if the vehicle starts to slide down the slope after that. It sometimes became unstable.

  That is, when the vehicle starts to slide down the slope, even if the vehicle is released from the brake pedal, the braking state is maintained and the wheels do not rotate. Therefore, when the posture of the vehicle sliding down the slope becomes unstable and the direction of the vehicle begins to change, it is not possible to stop the change in the posture of the vehicle even if the steering wheel is operated by removing the foot from the brake pedal, There is a risk that the vehicle will roll over because the vehicle is at a right angle to the slope direction of the slope, or that the vehicle may come into contact with people or buildings on the slope.

  In addition, when the vehicle starts to change its position while sliding down after stopping on an uphill slope, even if the braking state is released by operating the accelerator pedal or the like, the driver is likely to make an error in operating the steering wheel.

  For example, as shown in FIG. 6, when the posture of a vehicle that slides backward starts to change to the right, the driver often turns the steering wheel to the left to return the vehicle to its original position. However, when the steering wheel is turned counterclockwise to steer the wheels FR and FL, the change in the posture of the vehicle is promoted as shown in FIG. 7, and the vehicle becomes more dangerous. On the other hand, when the steering wheel is turned to the right to steer the wheels FR and FL, the vehicle can be returned to the posture before the change as shown in FIG.

As described above, when the posture of the vehicle that has slipped down the slope starts to change, it is necessary to prevent an accident caused by an erroneous steering operation by the driver.
JP 59-179439 A

  The problem to be solved by the present invention is to provide a vehicle control device capable of suppressing a change in posture of a vehicle in a braking state when the vehicle starts to change posture while sliding down a slope. It is.

  In order to solve the above-described problem, when the brake holding control means for performing control to hold the braking state by the brake device when the vehicle stops, and the braking state holding by the brake holding control means, Attitude change detecting means for detecting a change in attitude of the vehicle sliding down the slope, and braking hold releasing means for releasing the holding of the braking state by the brake holding control means when the attitude change detecting means detects a change in the attitude of the vehicle. And steering assist control means for performing control for assisting vehicle steering and suppressing changes in the posture of the vehicle when the braking and holding control means releases the braking state by the braking and holding release means. The configuration is adopted in the vehicle control device.

The steering assist control means can be configured as follows, for example.
1) When the brake holding release means releases the holding state of the braking state by the brake holding release means, the steering wheel is controlled to rotate in the steering direction to return the vehicle to the position before the change.
2) Control of steering the wheel in the steering direction to return the vehicle to the pre-change posture independently of the operation of the steering wheel when the brake holding release by the brake holding control unit is released by the brake holding release unit To do.
3) When the brake holding release means releases the holding state of the braking state by the brake holding release means, the driver is informed of the steering direction for returning the vehicle to the position before the change.

  The steering assist control means includes, for example, an inclination direction determination means for determining whether the inclination direction of the hill is an upward inclination or a downward inclination based on a detection signal of a longitudinal G sensor that detects acceleration in the longitudinal direction of the vehicle, and an angular velocity of the vehicle Based on the detection signal of the yaw rate sensor that detects the vehicle, the attitude change direction determination means that determines whether the attitude change of the vehicle is rightward or leftward based on the attitude when the vehicle is stopped, and the inclination direction determination means And a posture return steering direction determination means for determining a steering direction for returning the vehicle to the posture before the change based on the inclination direction of the slope and the posture change direction determined by the posture change direction determination means. Can do.

The posture change detection means can be configured as follows, for example.
1) Based on a detection signal from a yaw rate sensor that detects the angular velocity of the vehicle, a change in the posture of the vehicle that slides down the slope is detected.
2) Based on the amount of change in the detection signal of the lateral G sensor that detects the lateral acceleration of the vehicle, a change in the posture of the vehicle sliding down the slope is detected.
3) Based on the amount of change in the detection signal of the gyro sensor that detects the posture angle of the vehicle, a change in the posture of the vehicle sliding down the slope is detected.

  In this vehicle control device, when the braking state is maintained by the braking / holding control means and the vehicle starts to change posture while sliding down the slope, the posture change detecting means detects the change in posture and maintains the braking state. To release. Therefore, the wheels start to rotate, and it becomes possible to suppress changes in the posture of the vehicle by steering the wheels. Further, when the holding of the braking state is released, the steering assist control means supports the vehicle steering and suppresses the change in the posture of the vehicle, so that an accident caused by an erroneous steering operation by the driver is prevented.

  In addition, the steering assist control means that performs control to rotate the steering wheel in the steering direction that returns the vehicle to the posture before the change is performed when the driver starts to change the posture of the vehicle that slides down the slope. Even if an attempt is made to operate the steering wheel in the wrong direction, the steering operation is corrected and the change in the posture of the vehicle is suppressed.

  In addition, the steering assist control means controls the steering of the wheels in the steering direction to return the vehicle to the posture before the change independently of the operation of the steering wheel. If the driver starts to change, even if the driver operates the steering wheel in the wrong direction, the wheel is steered without correcting the steering operation. Therefore, it is possible to suppress a change in the posture of the vehicle without causing the driver to feel uncomfortable.

  In addition, the steering assist control means that informs the driver of the steering direction for returning the vehicle to the posture before the change is made when the driver starts to change in the wrong direction when the posture of the vehicle sliding down the slope begins to change. It prevents the steering wheel from being operated and suppresses the change in the posture of the vehicle.

  1 and 2 show a vehicle brake device and a steering device controlled by the vehicle control device according to the embodiment of the present invention. The brake device shown in FIG. 1 has a master cylinder 2 that converts the depression force of the brake pedal 1 into hydraulic pressure, and a master reservoir 3 that stores brake fluid is attached to the master cylinder 2. The master reservoir 3 supplies brake fluid to the master cylinder 2 and collects excess brake fluid from the master cylinder 2.

  The master cylinder 2 has pressure chambers 2A and 2B, and one pressure chamber 2A includes a master cylinder side pipe 4A, a master cut valve 5A, a pressure increase pipe 6A, a pressure increase control valve 7RL, and a wheel cylinder side pipe. The wheel cylinder side pipe line 8RL is connected to the pressure reducing pipe line 11A via the pressure reducing control valve 10RL. Similarly, the pressure increase pipe line 6A is connected to the wheel cylinder 9FR via a pressure increase control valve 7FR and a wheel cylinder side pipe line 8FR, and the wheel cylinder side pipe line 8FR is connected to the pressure reduction pipe via a pressure reduction control valve 10FR. It is connected to the road 11A. The pressure increase control valves 7RL and 7FR are normally open solenoid valves, and the pressure reduction control valves 10RL and 10FR are normally closed solenoid valves.

  The wheel cylinder 9RL is operated by the hydraulic pressure supplied from the wheel cylinder side pipe line 8RL, whereby the wheel cylinder 9RL presses a pad (not shown) against the disk 12RL that rotates integrally with the left rear wheel. Apply braking force to the left rear wheel. Similarly, the wheel cylinder 9FR also operates with the hydraulic pressure supplied from the wheel cylinder side pipe line 8FR, and presses a pad (not shown) against the disk 12FR that rotates integrally with the right front wheel.

  The pressure increasing line 6A and the pressure reducing line 11A are connected via a pump 13A. When the pump 13A is driven by the motor 14, the brake fluid is sent from the pressure reducing line 11A to the pressure increasing line 6A. A check valve 15A is provided on the discharge side of the pump 13A, and the check valve 15A prevents the backflow of the brake fluid from the pressure increasing line 6A to the pressure reducing line 11A.

  The front and rear of the master cut valve 5A are connected via a bypass line 16A. The bypass line 16A is provided with a check valve 17A that allows only the flow from the master cylinder side line 4A to the pressure increasing line 6A. Yes. Therefore, when the brake pedal 1 is depressed with the master cut valve 5A closed, the hydraulic pressure generated in the pressure chamber 2A is supplied to the pressure increasing line 6A through the check valve 17A, and the hydraulic pressure is applied from the brake pedal 1 to the foot. Even after the release, the pressure increase pipe 6A is held.

  Further, the pressure reducing line 11A and the master cylinder side line 4A are connected via an auxiliary reservoir 18A.

  The auxiliary reservoir 18A has a cylinder 19A and a piston 20A slidably inserted into the cylinder 19A. The cylinder 19A incorporates a spring 22A that urges the piston 20A in a direction to reduce the volume of the reservoir chamber 21A formed by the cylinder 19A and the piston 20A.

  The cylinder 19A is formed with a first port 23A for communicating the reservoir chamber 21A with the master cylinder side conduit 4A, and a second port 24A for communicating the reservoir chamber 21A with the decompression conduit 11A. A piston rod 25A extending toward the first port 23A is connected to the piston 20A, and a valve seat 26A and a valve body 27A supported by the tip of the piston rod 25A are provided at the first port 23A.

  In the auxiliary reservoir 18A, when the hydraulic pressure is supplied to the master cylinder side pipe line 4A by the operation of the brake pedal 1, the hydraulic pressure in the reservoir chamber 21A increases, and the piston 20A moves in a direction to compress the spring 22A. Therefore, the piston rod 25A moves integrally with the piston 20A, the valve body 27A is seated on the valve seat 26A, and the flow of brake fluid from the master cylinder side pipe line 4A to the reservoir chamber 21A is blocked.

  On the other hand, when the pump 13A is driven and brake fluid is sent from the pressure reducing line 11A to the pressure increasing line 6A, the hydraulic pressure in the reservoir chamber 21A decreases, the piston 20A moves in a direction to restore the spring 22A, and the piston rod 25A. Pushes and moves the valve body 27A away from the valve seat 26A. Therefore, the brake fluid can flow into the reservoir chamber 21A from the master cylinder side pipeline 4A, and the brake fluid in the master cylinder side pipeline 4A is supplied to the decompression pipeline 11A via the reservoir chamber 21A.

  A hydraulic system similar to the hydraulic system connected to the pressure chamber 2A is also connected to the other pressure chamber 2B of the master cylinder 2, and the hydraulic pressure is supplied to the wheel cylinders 9FL, 9RR through the hydraulic system. Can be done.

  As shown in FIG. 3, wheel speed sensors 28RL, 28FR, 28FL, 28RR for detecting the rotational speed of each wheel, an accelerator pedal sensor 29 for detecting an accelerator operation by the driver, and a brake pedal sensor for detecting a brake operation by the driver. 30, a yaw rate sensor 31 that detects the angular velocity of the vehicle, and a front / rear G sensor 32 that detects acceleration in the longitudinal direction of the vehicle are attached to the vehicle. Is sent to 33). The brake ECU 33 outputs control signals for the master cut valves 5A and 5B, the pressure increase control valves 7RL to 7RR, the pressure reduction control valves 10RL to 10RR, and the pump drive motor 14.

  This brake device can perform normal braking with the pressure increase control valves 7RL, 7FR, 7FL, 7RR opened and the pressure reduction control valves 10RL, 10FR, 10FL, 10RR closed. In addition, when the vehicle stops, the brake device maintains the braking state of each wheel even when the foot is released from the brake pedal 1, and the braking state is released when the accelerator pedal is operated. Hold control is performed. The braking state may be maintained, for example, by closing the master cut valves 5A and 5B and maintaining the hydraulic pressures of the wheel cylinders 9RL to 9RR, or driving the pumps 13A and 13B to each wheel cylinder 9RL. You may carry out by supplying hydraulic pressure to -9RR.

  On the other hand, the steering apparatus shown in FIG. 2 includes a steering wheel 34 operated by a driver, and a steering shaft 35 that rotates integrally with the steering wheel 34. A torque sensor 36 that detects an operation torque of the steering wheel 34 and a steering motor 38 that applies a rotational force to the steering shaft 35 via a gear 37 are attached to the steering shaft 35. The steering shaft 35 is connected to the tie rod 40 via a rack and pinion mechanism 39. When the steering shaft 35 rotates, the tie rod 40 moves in the left-right direction, and the wheels FR and FL are steered.

  The output signal of the torque sensor 36 is sent to a steering electronic control device (hereinafter referred to as “steering ECU”) 41 shown in FIG. 3, and the steering ECU 41 outputs a control signal for the steering motor 38. A signal is also input / output between the steering ECU 41 and the brake ECU 33.

  In this steering device, the operating force of the steering wheel 34 by the driver is detected by the torque sensor 36, and the assisting force corresponding to the operating force is applied to the steering shaft 35 by the steering motor 38, so that the operating force of the steering wheel 34 by the driver is applied. To assist. It is also possible to correct the operation of the steering wheel 34 by the driver by driving the steering motor 38 regardless of the operating force detected by the torque sensor 36 and forcibly rotating the steering shaft 35.

  Control of the brake device configured as described above will be described based on the flowcharts of FIGS. 4 and 5.

First, on the assumption that neither the accelerator nor the brake is operated (steps S ₁ and S ₂ ), it is determined whether or not the braking state is maintained by the braking holding control (step S ₃ ). When it is determined that the braking state is maintained, the posture angle around the vertical axis of the vehicle when the braking state is started is set to zero (steps S ₄ and S ₅ ), and the yaw rate is set to the posture angle. The angular velocities detected by the sensor 31 are integrated (step S ₆ ), and the current attitude angle around the vertical axis of the vehicle is calculated.

Then, based on the detection signal of the wheel speed sensor 28RL~28RR wheel speed of each wheel to determine all whether zero (step S _7), when the wheel speed of each wheel is determined to all zeros is followed Then, it is determined whether or not the angular velocity detected by the yaw rate sensor 31 is larger than a preset threshold value (step S ₈ ). When it is determined that the angular velocity detected by the yaw rate sensor 31 is greater than the threshold value, it is considered that the posture of the vehicle that has slipped down the slope is changed, so that the holding of the braking state by the braking holding control is canceled and the vehicle is sheared. The falling deflection state is set (steps S ₉ and S ₁₀ ).

When the braking state holding by the braking holding control is canceled and the sliding deflection state is set (steps S ₃ and S ₁₁ ), the slope direction of the slope detected by the front and rear G sensor 32 and the posture angle of the vehicle are set. Based on this, steering assist control for rotating the steering wheel 34 in the steering direction to return the vehicle to the position before the change is performed (step S ₁₃ ). The attitude angle of the vehicle is updated based on the angular velocity detected by the yaw rate sensor 31 even during the steering assist control (step S ₁₂ ). Thereafter, when the accelerator or the brake is operated (steps S ₁ and S ₂ ), the slip-down deflection state is canceled and the steering assist control is ended (step S ₁₄ ).

The steering assist control will be described based on a subroutine shown in FIG. Based on the detection signal of the front / rear G sensor 32, it is determined whether or not the inclination direction of the slope is an upward inclination (step S ₂₁ ). determines whether the direction (step _S 22). If it is determined that the vehicle is in the right direction, it is determined that the steering direction of the wheels FR, FL for returning the vehicle to the posture before the change is the right direction, and the steering shaft 35 is rotated to the right (step S ₂₃ ). Meanwhile, when the change in the attitude of the vehicle is determined not to be the right direction (step S _22), the wheels FR back into position before the change of the vehicle, the steering direction of the FL is determined to be a left direction, the left steering shaft 35 (Step S ₂₄ ).

Similarly, when it is determined that the slope direction of the slope is not an upward slope (step S ₂₁ ), it is determined whether or not the change in the posture of the vehicle is rightward (step S ₂₅ ). The shaft 35 is rotated counterclockwise (step S ₂₆ ). On the other hand, when it is determined that the posture change of the vehicle is not rightward (step S ₂₅ ), the steering shaft 35 is rotated to the right (step S ₂₇ ).

  When this vehicle control device is used, the holding of the braking state by the braking holding control is canceled if the angular velocity of the vehicle becomes larger than the threshold value when the braking state is held by the braking holding control. Therefore, when a vehicle that has been kept in a braking state on a slope begins to change its posture while sliding down the slope, the maintenance of the braking state is released and the wheels RL to RR start to rotate, and the vehicle is operated by steering the wheels FR and FL. It becomes a state where it is possible to suppress the posture change. Furthermore, since the steering shaft 35 is rotated by the steering motor 38 in the steering direction to return the vehicle to the posture before the change, even if the driver tries to operate the steering wheel 34 in the wrong direction, the steering operation is corrected and the vehicle posture Change is suppressed.

  For example, as shown in FIG. 6, when the posture of the vehicle that slides backward starts to change to the right, if the driver accidentally turns the steering wheel 34 to the left and steers the wheels FR and FL to the left, FIG. As shown, the vehicle attitude change is promoted, but this vehicle control device rotates the steering shaft 35 to the right and turns the wheels FR and FL to the right when the attitude change of the vehicle is rightward on an uphill slope. Since the steering is performed, the posture of the vehicle returns to the posture before the change as shown in FIG.

  Similarly, when the posture of the vehicle that slides forward starts to change to the right as shown in FIG. 9, the vehicle control device moves the steering shaft 35 when the vehicle posture change is in the right direction on the downhill slope. Since the wheels FR and FL are steered to the left by rotating to the left, the posture of the vehicle returns to the posture before the change as shown in FIG.

In the above-described embodiment, the change in the posture of the vehicle sliding down the slope is detected based on the angular velocity of the vehicle detected by the yaw rate sensor 31, but the change in the posture of the vehicle may be detected by another method. For example, a lateral G sensor for detecting the lateral acceleration of the vehicle is provided in the vehicle, and as shown in FIG. 11, the lateral G sensor based on the time when the wheel speed of each wheel becomes zero (time T ₀ ). When the change amount of the detection signal becomes larger than the preset threshold value G ₀ (time T ₁ ), it may be determined that the posture of the vehicle sliding down the slope is changing. Further, a gyro sensor for detecting the attitude angle of the vehicle is provided in the vehicle, and as shown in FIG. 12, the change in the detection signal of the gyro sensor with reference to the time when the wheel speed of each wheel becomes zero (time T ₀ ). When the amount becomes larger than the preset threshold value S ₀ (time T ₂ ), it may be determined that the posture of the vehicle sliding down the slope is changing.

  In the present invention, the tie rod 40 can be moved independently of the operation of the steering wheel 34, and a drive device for moving the tie rod 40 and a rotation angle sensor for detecting the rotation angle of the steering wheel 34 are provided. It can also be applied to a so-called by-wire type steering device in which the tie rod 40 is moved by a driving device in accordance with the rotation angle detected in step (b). In this case, the steering assist control of the above embodiment can be replaced with control for steering the wheels FR and FL in the steering direction to return the vehicle to the posture before the change independently of the operation of the steering wheel 34. In this way, when the attitude of the vehicle that has slipped down the slope begins to change, even if the driver operates the steering wheel 34 in the wrong direction, the wheel is steered without correcting the steering operation. A change in the posture of the vehicle can be suppressed without giving a sense of incongruity.

  Further, the steering assist control of the above embodiment may be replaced with control for notifying the driver of the steering direction for returning the vehicle to the posture before the change. In this way, when the posture of the vehicle that has slipped down the slope starts to change, it is possible to prevent the driver from operating the steering wheel 34 in the wrong direction and to suppress the change in the posture of the vehicle. The notification to the driver is performed by voice guidance or image display, for example.

Piping system diagram showing a vehicle brake device controlled by a vehicle control device of an embodiment of the present invention The figure which shows the steering apparatus of the vehicle controlled by a vehicle control apparatus same as the above Block diagram of the vehicle control device Flow chart showing control of vehicle control apparatus as above FIG. 4 is a flowchart showing the steering assist control subroutine of FIG. The figure which shows the state where the posture of the vehicle that slides backward starts to change to the right The figure which shows the state which steered the wheel to the left from the state of FIG. The figure which shows the state which steered the wheel to the right from the state of FIG. The figure which shows the state where the posture of the vehicle that slides forward starts to change to the right The figure which shows the state which steered the wheel to the left from the state of FIG. Explanatory drawing of the modification which detects the attitude | position change of a vehicle based on the variation | change_quantity of the detection signal of a lateral G sensor. Explanatory drawing of the modification which detects the attitude | position change of a vehicle based on the variation | change_quantity of the detection signal of a gyro sensor.

Explanation of symbols

31 Yaw rate sensor 32 Front / rear G sensor 34 Steering wheel RL, FR, FL, RR Wheel

Claims (8)

Braking holding control means for performing control to hold the braking state by the brake device when the vehicle stops;
Attitude change detection means (S ₈ ) for detecting a change in the attitude of the vehicle sliding down the slope when the braking state is held by the brake holding control means;
Braking holding releasing means (S ₉ ) for releasing the holding of the braking state by the braking holding control means when the attitude change detecting means (S ₈ ) detects a change in the posture of the vehicle;
Steering assistance control means for performing control for supporting vehicle steering and suppressing a change in the posture of the vehicle when the braking holding release means (S ₉ ) releases the holding state of the braking state by the braking holding control means. S ₁₃ ),
A vehicle control device. The steering assist control means (S ₁₃ ) steers the steering wheel in the steering direction to return the vehicle to the position before the change when the braking hold release means (S ₉ ) releases the holding state of the braking state by the brake holding control means. The vehicle control device according to claim 1, wherein control for rotating (34) is performed. The steering assist control means (S ₁₃ ) is independent of the operation of the steering wheel (34) when the braking hold release means (S ₉ ) releases the holding state of the braking state by the braking hold control means. The vehicle control device according to claim 1, wherein control is performed to steer the wheels (FR, FL) in a steering direction for returning the vehicle to a posture before change. The steering assist control means (S ₁₃ ) gives the driver a steering direction for returning the vehicle to the pre-change posture when the braking holding release means (S ₉ ) releases the holding state of the braking state by the braking holding control means. The vehicle control device according to claim 1, which performs notification. The steering assist control means (S ₁₃ )
Inclination direction determination means (S ₂₁ ) for determining whether the inclination direction of the slope is ascending or descending based on a detection signal of the longitudinal G sensor (32) for detecting acceleration in the longitudinal direction of the vehicle;
Based on the detection signal of the yaw rate sensor (31) for detecting the angular velocity of the vehicle, the attitude the attitude change of the vehicle on the basis of when the vehicle is stopped and determines the posture change direction determination means for determining the right direction or left direction (S ₂₂ , S ₂₅ ),
Based on the inclination direction of the slope determined by the inclination direction determining means (S ₂₁ ) and the direction of the attitude change determined by the attitude change direction determining means (S ₂₂ , S ₂₅ ), the vehicle is returned to the posture before the change. Attitude return steering direction determining means (S ₂₃ , S ₂₄ , S ₂₆ , S ₂₇ ) for determining the steering direction;
The vehicle control device according to claim 2, comprising: The posture change detection means (S _8), based on the detection signal of the yaw rate sensor (31) for detecting the angular velocity of the vehicle, from claim 1 for detecting a change in the attitude of the vehicle slipping the slope according to any one of the 5 Vehicle control device. The posture change detecting means (S ₈ ) detects a posture change of a vehicle that slides down a hill based on a change amount of a detection signal of a lateral G sensor that detects a lateral acceleration of the vehicle. The vehicle control device according to claim 1. The posture change detection means (S ₈ ) detects a posture change of a vehicle that slides down a hill based on a change amount of a detection signal of a gyro sensor that detects a posture angle of the vehicle. Vehicle control device.

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