JP2010052523A - Driving force distribution control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving force distribution control device capable of enhancing the avoidance performance in a vehicle having an obstacle avoidance supporting device. <P>SOLUTION: A vehicle has a driving force distribution control device 1 and an electric power steering device 2. The driving force distribution control device 1 comprises a front-and-rear wheel driving force distribution control unit 21 for distributing the driving forces of the front and rear wheels, a rear wheel right-to-left driving force distribution control unit 22 for controlling the yaw moment by differentiating the distribution of the driving forces of the right and left rear wheels, an actuator control unit 23, and a control gain calculation unit 24. The electric power steering device 2 has an avoidance operation support control unit 42 which detects any obstacle in front of the vehicle and supports the operation for avoiding any contact with the obstacle. When the avoidance operation support control unit 42 of the electric power steering device 2 controls the support of the steering operation for avoiding any contact with the obstacle, the gain of the yaw moment control in the rear wheel right-to-left driving force distribution control unit 22 is increased more than that in the normal condition. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a driving force distribution control device that controls yaw moment by varying the driving force distribution of left and right wheels.

  Some vehicles are provided with a driving force distribution control device that distributes the driving force of each wheel according to the traveling state in order to improve the motion performance. In this driving force distribution control device, for example, the yaw moment can be controlled by changing the driving force distribution of the left and right wheels, and the distribution of the driving force of the rear wheels (that is, the rear outer wheels) outside the turn is increased. Thus, an inward yaw moment can be generated to improve the turning performance (see, for example, Patent Document 1).

On the other hand, in a vehicle electric power steering device that reduces the driver's steering force during vehicle steering, the steering assist amount is controlled according to the steering torque during normal steering, and obstacles in front of the vehicle are detected by the obstacle detection device. In such a case, there is known one provided with avoidance support means for correcting the steering assist amount in a direction to support the avoidance operation (see, for example, Patent Document 2).
JP 2007-302024 A JP 2007-39017 A

According to the vehicle including the electric power steering device, it is easy to avoid contact with an obstacle.
However, the contact avoidance operation with the obstacle may be urgent, and further improvement in avoidance performance is desired.

  Therefore, the present invention provides a driving force distribution control device capable of improving avoidance performance in a vehicle equipped with an obstacle avoidance support device.

The driving force distribution control apparatus according to the present invention employs the following means in order to solve the above problems.
The invention according to claim 1 includes a left / right driving force distribution control unit (for example, a rear wheel left / right driving force distribution control unit 22 in an embodiment described later) that controls the yaw moment by varying the driving force distribution of the left and right wheels. In a driving force distribution control device (for example, a driving force distribution control device 1 in an embodiment described later), an obstacle avoidance support device (for example, assisting an operation for detecting an obstacle ahead of the vehicle and avoiding contact with the obstacle) The driving force distribution control device is characterized in that when the avoidance operation support control unit 42) in the embodiment described later is operating, the gain of the yaw moment control amount is increased more than usual.
By configuring in this way, when the obstacle avoidance support device is performing the avoidance operation support, the gain of the yaw moment control amount is increased as compared with the normal time, so that a larger yaw moment than the normal time can be obtained. it can. In this application, the normal time is a time when the obstacle avoidance assistance device does not support a steering operation that avoids contact with an obstacle, and a predetermined time has elapsed since the avoidance operation assistance operation ended. Say time.

According to a second aspect of the present invention, in the first aspect of the invention, the front and rear wheel driving force distribution control unit (for example, the front and rear wheel driving force distribution control unit 21 in the embodiment described later) that distributes the driving force of the front and rear wheels. The left and right wheels on which the left and right driving force distribution control unit distributes the driving force are rear wheels, and the front and rear wheel driving force distribution control unit moves to the front wheels when the obstacle avoidance support device supports the avoidance operation. The amount of driving force distribution is reduced.
With this configuration, when the obstacle avoidance assistance device assists the avoidance operation, the amount of driving force distribution to the front wheels is reduced, so that the amount of driving force distribution to the rear wheels is increased and a larger yaw amount is obtained. Moment can be obtained.

According to a third aspect of the present invention, in the first aspect of the present invention, the gain of the yaw moment control amount is increased from a normal time for a predetermined time immediately after the obstacle avoidance support device ends the avoidance operation support. And then returning to the normal gain.
With this configuration, the convergence of the vehicle behavior after the avoidance operation support can be accelerated.

  According to the first aspect of the present invention, since the vehicle can be easily turned while the obstacle avoidance assistance device is operating, the avoidance performance against the obstacle is improved.

  According to the second aspect of the present invention, since a larger yaw moment can be obtained, the avoidance performance against obstacles is further improved.

  According to the invention of claim 3, since the convergence of the vehicle behavior after the operation of the obstacle avoidance assistance device can be accelerated, the stabilization performance of the vehicle behavior after avoidance is improved.

Embodiments of a driving force distribution control apparatus according to the present invention will be described below with reference to the drawings of FIGS.
The vehicle in this embodiment is a four-wheel drive vehicle, and includes a driving force distribution control device 1 and an electric power steering device 2 as shown in the block diagram of FIG. In other words, the driving force distribution control device 1 in this embodiment is mounted on a vehicle provided with the electric power steering device 2.
First, the electric power steering device 2 will be described. The electric power steering device 2 includes an electric assist motor (hereinafter abbreviated as an assist motor) 51 that generates a steering assist torque, a motor drive circuit 52 that drives the assist motor 51, and an electric power steering control device (hereinafter referred to as an EPS control device). Abbreviated as 40).

  The EPS control device 40 includes a radar 11 that detects an obstacle ahead of the vehicle, a steering torque sensor 12 that detects a steering torque applied to the steering shaft, a wheel speed sensor 13 that detects a wheel speed of each wheel, Output signals corresponding to the detected values are input from the yaw rate sensor 14 that detects the yaw rate of the vehicle and the steering angle sensor 15 that detects the steering angle.

  The radar 11 transmits an electromagnetic wave such as a millimeter wave toward the front of the vehicle body, detects an obstacle based on the reflected wave, a relative distance between the obstacle and the own vehicle, a relative speed between the obstacle and the own vehicle, The offset distance between the obstacle and the vehicle and the width of the obstacle are detected. The offset distance between the obstacle and the own vehicle refers to a shift amount in the vehicle width direction between the center of the obstacle and the center of the own vehicle.

The EPS control device 40 includes an EPS basic control unit 41 and an avoidance operation support control unit (obstacle avoidance support device) 42.
The EPS basic control unit 41 assists based on the vehicle speed (vehicle speed) calculated based on the rotational speed of each wheel detected by the wheel speed sensor 13 and the steering torque detected by the steering torque sensor 12. The EPS basic control amount EPS_VALUE of the motor 51 is calculated. The method for calculating the EPS basic control amount EPS_VALUE is the same as that of a known electric power steering device, and thus detailed description thereof is omitted. However, generally, as the steering torque increases, the EPS basic control amount EPS_VALUE increases and the vehicle speed increases. Accordingly, the EPS basic control amount EPS_VALUE is set to be small.

The avoidance operation support control unit 42 determines whether or not it is necessary to assist the steering operation in order to avoid contact with an obstacle in front of the vehicle detected by the radar 11. A control correction amount EPS_HOSEI_VALUE for avoidance support is calculated.
More specifically, the avoidance operation support control unit 42 calculates the predicted course of the host vehicle based on the detection values of various sensors, the detection result of the radar 11 (the relative distance and relative speed between the obstacle and the host vehicle, the offset). Based on the distance and the width of the obstacle), it is determined whether or not there is an obstacle on the predicted course. If it is determined that an obstacle exists on the predicted course, the avoidance momentum (lateral movement amount) necessary for the vehicle to avoid contact with the obstacle is calculated, and control is performed according to the avoidance momentum. A correction amount EPS_HOSEI_VALUE is calculated.

  The avoidance operation support control unit 42 drives the avoidance support flag XHK_F = 1 when assisting the steering operation in order to avoid contact with an obstacle (hereinafter referred to as “in operation for avoidance operation support”). When the steering operation is not supported in order to output to the force distribution control device 1 and avoid contact with an obstacle (hereinafter referred to as “avoidance operation support inactive”), the avoidance support flag XHK_F = 0 is driven. Output to the force distribution control device 1.

Then, the EPS control device 40 adds the control correction amount EPS_HOSEI_VALUE to the EPS basic control amount EPS_VALUE, obtains the target current Io of the assist motor 51, and outputs this target current Io to the motor drive circuit 52.
In the motor drive circuit 52, feedback control is performed so that the actual current of the assist motor 51 matches the target current Io.

  Next, the driving force distribution control device 1 will be described. The driving force distribution control device 1 includes a driving force distribution control unit 20 and a driving force distribution actuator 30. The driving force distribution control unit 20 includes a front and rear wheel driving force distribution control unit 21, a rear wheel left and right driving force distribution control unit (left and right driving force distribution control unit) 22, an actuator control unit 23, a control gain calculation unit 24, It is configured with.

  The driving force distribution control unit 20 includes a wheel speed sensor 13, a yaw rate sensor 14, a steering angle sensor 15, a lateral acceleration sensor 16 that detects vehicle lateral acceleration (hereinafter referred to as lateral acceleration), and a vehicle longitudinal acceleration (hereinafter referred to as lateral acceleration). Output signals corresponding to the detected values and an estimated driving torque value are input from the longitudinal acceleration sensor 17 that detects the longitudinal acceleration). The estimated drive torque is calculated based on the engine speed, the engine cylinder intake air amount, the output shaft speed of the torque converter, the shift position of the transmission, and the like.

  The front / rear wheel driving force distribution control unit 21 and the rear wheel left / right driving force distribution control unit 22 are configured to calculate the vehicle speed based on the rotational speed of each wheel detected by the wheel speed sensor 13 and the yaw rate detected by the yaw rate sensor 14. The vehicle running state is detected based on information such as the steering angle detected by the steering angle sensor 15, the lateral acceleration detected by the lateral acceleration sensor 16, and the longitudinal acceleration detected by the longitudinal acceleration sensor 17, The front-rear wheel driving force distribution and the rear-wheel left-right driving force distribution are performed so as to achieve the optimum driving force distribution according to the detected traveling state.

  For example, when it is detected that the vehicle is in a traveling state where the vehicle starts or suddenly accelerates, the load moves later in this traveling state, so the front and rear wheel driving force distribution control unit 21 drives the driving force to the rear wheels. Increase the distribution of the drive and improve the driving performance. Further, when it is detected that the vehicle is in a cruise traveling state, the front and rear wheel driving force distribution control unit 21 reduces the distribution of driving force to the rear wheels in order to improve the straight running stability. As described above, the front and rear wheel driving force distribution control unit 21 calculates the driving force distribution of the front wheels and the rear wheels according to the traveling state of the vehicle, and calculates the front wheel driving torque (front wheel driving) calculated according to the calculated driving force distribution. Torque) F_VALUE is output.

  In addition, when it is detected that the vehicle is turning, the rear wheel left / right driving force distribution control unit 22 determines that the rear wheel outside the turn (hereinafter referred to as the rear wheel inner wheel) (hereinafter referred to as the rear wheel inner wheel). , The rear wheel outer wheel) increases the distribution of driving force and generates an inward yaw moment to improve the turning performance. As described above, the rear wheel left / right driving force distribution control unit 22 calculates the driving force distribution of the inner and outer wheels of the rear wheel in accordance with the traveling state of the vehicle, and the amount of increase in the driving torque of the outer wheel with respect to the driving torque of the inner wheel (hereinafter, rear R_VALUE (referred to as an increase in outer wheel drive torque). In this embodiment, the rear wheel outer wheel drive torque increase amount R_VALUE can be said to be a yaw moment control amount for controlling the yaw moment of the vehicle.

The control gain calculation unit 24 calculates a front wheel driving force gain F_GAIN and a rear wheel driving force gain R_GAIN based on the avoidance support flag XHK_F input from the avoidance operation support control unit 42 of the EPS control device 40. A method of calculating the front wheel driving force gain F_GAIN and the rear wheel driving force gain R_GAIN will be described in detail later.
Then, the front wheel drive torque F_VALUE calculated by the front and rear wheel drive force distribution control unit 21 is multiplied by the front wheel drive force gain F_GAIN calculated by the control gain calculation unit 24, and the product is input to the actuator control unit 23 as a front wheel drive force. In addition, the rear wheel outer wheel driving torque increase amount R_VALUE calculated by the rear wheel left / right driving force distribution control unit 22 is multiplied by the rear wheel driving force gain R_GAIN calculated by the control gain calculation unit 24, and the product is the rear wheel outer wheel. The drive torque increase amount is input to the actuator control unit 23.

The driving force distribution actuator 30 includes an actuator that operates a clutch and the like that distributes the driving force of the front and rear wheels, and an actuator that operates a clutch and the like that distributes the left and right driving force of the rear wheels.
The actuator control unit 23 calculates the control amount of each actuator of the driving force distribution actuator 30 based on the front wheel driving torque after gain adjustment and the rear wheel outer wheel driving torque increase amount after gain adjustment, and distributes the driving force. It outputs to the actuator 30 and controls each actuator of the driving force distribution actuator 30. As a result, the driving force is transmitted to each wheel of the vehicle by the distribution of the driving force of the front and rear wheels and the distribution of the driving force of the left and right rear wheels that are optimal for the traveling state of the vehicle.

Next, the control gain calculation process executed in the control gain calculation unit 24 will be described with reference to the flowchart of FIG. Note that the control gain calculation processing routine shown in the flowchart of FIG. 2 is repeatedly executed at regular intervals.
First, in step S101, based on the avoidance support flag XHK_F input from the avoidance operation support control unit 42, it is determined whether or not the avoidance operation support is inactive. That is, when the avoidance support flag XHK_F = 0 is input, the avoidance operation support control unit 42 does not execute the avoidance operation support. Therefore, an affirmative determination is made in step S101, and the avoidance support flag XHK_F = 1 is input. Sometimes, the avoidance operation support control unit 42 is executing the avoidance operation support, so a negative determination is made in step S101.

  If the determination result in step S101 is “NO” (operating), the process proceeds to step S102, and the front wheel driving force gain F_GAIN is set to a value (for example, 0.5) lower than the normal value (1.0). At the same time, the rear wheel driving force gain R_GAIN is set to a value (for example, 1.5) higher than the normal value (1.0), and the process returns.

  If the determination result in step S101 is “YES” (not operating), the process proceeds to step S103, and it is determined whether or not the avoidance support flag XHK_F = 1 when this routine was executed last time. That is, it is determined whether or not the routine that is executed this time is the first routine that is executed after the avoidance operation support operation is switched to the avoidance operation support non-operation.

If the determination result in step S103 is “YES” (first routine after switching), the process proceeds to step S104, and the timer value T of the gain adjustment timer is set to the initial value T0 (T = T0). The initial value T0 is a positive integer.
On the other hand, if the determination result in step S103 is “NO” (not the first routine after switching), the process proceeds to step S105, and one timer value T is subtracted (T = T−1).
Then, the process proceeds from step S104 or step S105 to step S106, and it is determined whether or not the timer value T is 0 or less.

  If the determination result in step S106 is “NO” (T> 0), the process proceeds to step S107, the front wheel driving force gain F_GAIN is returned to the normal value of 1.0, and the rear wheel driving force gain R_GAIN is normally set. A value (for example, 0) lower than the value (1.0) is set, and the process returns. When the rear wheel driving force gain R_GAIN is set to “0”, the rear wheel outer wheel driving torque increase amount becomes zero, so that the driving force distribution of the inner and outer wheels of the rear wheel becomes a neutral state of 50:50, and the rear wheel The same driving torque is transmitted to the inner and outer rings.

  On the other hand, if the determination result in step S106 is “YES” (T ≦ 0), the process proceeds to step S108 where the front wheel driving force gain F_GAIN is set to 1.0, which is a normal value, and the rear wheel driving force gain is set. Set R_GAIN to the normal value of 1.0 and return. The rear wheel driving force gain R_GAIN = 1.0 at this time is the value of the normal rear wheel driving force gain R_GAIN.

  That is, when the avoidance operation support operation is switched to the avoidance operation support non-operation, the front wheel driving force gain F_GAIN returns to the normal value of 1.0 immediately after the switching, but the rear wheel driving force gain R_GAIN is changed to the normal value of 1 immediately after the switching. Rather than returning to .0, a predetermined time (timer initial value × routine cycle) after switching is set to a value lower than the normal value, and when the predetermined time elapses, the normal value is returned to 1.0. I have to. The predetermined time can be appropriately set, but is preferably set to 0.1 to 1.0 seconds, for example.

According to the driving force distribution control device 1 configured as described above, during the avoidance operation support operation, the rear wheel driving force gain R_GAIN is set higher than normal, so that a yaw moment larger than normal can be obtained. The vehicle can be easily turned. Therefore, the avoidance performance against the obstacle is improved.
Further, during the avoidance operation assisting operation, the front wheel driving force gain F_GAIN is set lower than usual, so that the amount of driving force distribution to the rear wheels increases. Thereby, since a larger yaw moment can be obtained, the vehicle can be made easier to turn, and the avoidance performance against obstacles is further improved.

  As a result of such control, it is predicted that the vehicle is oversteered immediately after the avoidance operation support operation is completed. Therefore, in the driving force distribution control device 1 of this embodiment, when the avoidance operation support operation is switched to the avoidance operation support non-operation, the rear wheel drive force gain R_GAIN is not switched back to the normal value of 1.0 immediately after the switching, but is switched. The amount of increase in the rear wheel outer wheel drive torque is reduced from the normal value by maintaining the value lower than the normal value for a predetermined time after that (in the embodiment, by setting R_GAIN = 0, the rear wheel inner / outer wheel drive force is the same). When the predetermined time has elapsed, the normal value is returned to 1.0, thereby speeding up the convergence of the vehicle behavior after the end of the avoidance operation support operation. Thereby, the stabilization performance of the vehicle behavior after avoidance improves.

Next, the control procedure of the driving force distribution actuator 30 of the driving force distribution control device 1 and the control procedure of the assist motor 51 of the electric power steering device 2 will be described with reference to the flowchart of FIG.
First, in step S201, it is determined whether or not avoidance operation support for an obstacle is necessary.
In step S202, the driving force distribution control device 1 calculates driving force distribution (front and rear wheel driving force distribution and rear wheel left and right driving force distribution).
Next, it progresses to step S203 and the control gain (front wheel driving force gain F_GAIN and rear wheel driving force gain R_GAIN) of the driving force distribution control apparatus 1 is calculated.
Next, the process proceeds to step S204, and the driving force distribution actuator 30 is controlled based on the driving force distribution calculated in step S202 and the control gain calculated in step S203.
In step S205, the control amount (target current Io) of the assist motor 51 of the electric power steering apparatus 2 is calculated.
Next, the process proceeds to step S206, and the assist motor 51 is controlled.

[Other Examples]
The present invention is not limited to the embodiment described above.
For example, the value of the rear wheel driving force gain R_GAIN when it is higher than the normal value is not limited to 1.5, and the value of the rear wheel driving force gain R_GAIN when it is lower than the normal value is limited to 0. It can be set to appropriate values.
Further, the value of the front wheel driving force gain F_GAIN when it is lower than the normal value is not limited to 0.5, and can be set to an appropriate value.

It is a block diagram in the Example of the vehicle provided with the driving force distribution control apparatus which concerns on this invention. It is a flowchart which shows the control gain calculation process in an Example. It is a flowchart which shows the control procedure of the driving force distribution control apparatus in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Driving force distribution control apparatus 2 Electric power steering apparatus 21 Front-and-rear wheel driving force distribution control part 22 Rear wheel left-right driving force distribution control part (left-right driving force distribution control part)
23 control gain calculation unit 42 avoidance operation support control unit (obstacle avoidance support device)

Claims (3)

In the driving force distribution control device including a left and right driving force distribution control unit that controls the yaw moment by varying the driving force distribution of the left and right wheels,
When an obstacle avoidance assistance device that detects an obstacle ahead of the vehicle and supports an operation for avoiding contact with the obstacle is operating, the gain of the yaw moment control amount is increased more than usual. Driving force distribution control device.   A front and rear wheel driving force distribution control unit that distributes the driving force of the front and rear wheels, the left and right wheels that the left and right driving force distribution control unit distributes the driving force are rear wheels, and the obstacle avoidance support device supports the avoidance operation 2. The driving force distribution control device according to claim 1, wherein the front and rear wheel driving force distribution control unit reduces the amount of driving force distribution to the front wheels.   The gain of the yaw moment control amount is decreased from the normal time for a predetermined time immediately after the obstacle avoidance support device ends the avoidance operation support, and then returned to the normal gain. The driving force distribution control device according to claim 1.

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