JP2010254268A - Steering control vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering control vehicle capable of stabilizing behavior of vehicle further if a steering control means cannot control it any more. <P>SOLUTION: This automobile V has variable mechanisms 6 for rear wheel tow angle provided on the right and left rear wheels 3r and damping force variable dampers 4 and stabilizers 8 provided on the right and left front wheels 3f and the right and left rear wheels 3r, respectively. An ECU 20 corrects target damping force of the dampers 4 on the front wheels 3 to increase its value (step S6) and corrects target roll rigidity of the front stabilizer 8f to increase its value (step S7) if a failure detection part 34 detects failure in both of right and left variable mechanisms 6 for rear wheel tow angle (step S5:Yes). The ECU 20 also sets the target damping force of the rear wheel 3r causing failure to a small value (steps S11, S13) and corrects the target roll rigidity of the front stabilizer 8f to increase its value (step S7) if the failure detection part 34 detects failure in either of the right and left variable mechanisms 6 for rear wheel tow angle (step S5:No). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a steering control vehicle having steering control means, and relates to a technique for stabilizing vehicle behavior using another control means when any one of the steering control means fails.

  In recent years, in order to improve turning performance and steering stability of a vehicle, a four-wheel steering vehicle having a rear wheel toe angle varying device that variably controls a toe angle of a rear wheel has been developed. As the rear wheel toe angle variable device, the left and right rear wheels are each provided with an electric actuator that linearly displaces the lateral link in the suspension device supporting the rear wheel or the connecting portion of the trailing link to the vehicle body, and these are driven to extend and contract. A configuration in which the toe angles of the left and right wheels can be individually variably controlled is known (for example, Patent Document 1).

  In a vehicle equipped with such a rear wheel toe angle variable device that variably controls the rear wheel toe angle, when the electric actuator operates different from the control command value due to a failure of the left and right rear wheel toe angle variable devices (self (Steer) or when the electric actuator stops operating (fixed), unexpected rear wheel lateral force or yaw moment may occur, and improvement in vehicle behavior stability may not be expected. In order to cope with such a problem, the rear wheel toe angle varying device capable of independently controlling the toe angles of the left and right rear wheels stabilizes the vehicle behavior by controlling the toe angles of the non-failed wheels. Has a fail-safe function.

Japanese Patent Laid-Open No. 9-30438

  However, even if the rear wheel toe angle varying device has the fail-safe function as described above, both the rear wheels are caused by the failure of a control device such as an ECU (Electronic Control Unit) or the disconnection of the power supply line to the electric actuator. If the toe angle control becomes impossible, the stability of the vehicle behavior cannot be improved by controlling the rear wheel toe angle. In addition, even if the rear wheel toe angle varying device on either the left or right side breaks down, the cornering force of the outer wheel increases during turning, which affects the behavior of the vehicle. The function may not sufficiently contribute to the stabilization of the vehicle behavior.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a steering control vehicle capable of further stabilizing the vehicle behavior when the steering control means becomes uncontrollable.

  In order to solve the above-mentioned problem, the first invention is a steering control means (rear wheel toe angle varying mechanism 6) provided on at least one of the left and right front wheels (3f) and the left and right rear wheels (3r), and the left and right front wheels. (3f) and a steering wheel having suspension stiffness control means (active stabilizer 8) provided on at least one of the left and right rear wheels (3r) and a failure detection means (34) for detecting a failure of the steering control means (6) When a failure is detected in the left and right steering control means (6) by the failure detection means (34) in the controlled vehicle (V), the suspension rigidity control means (8) has a failure in the steering control means (6). The suspension rigidity of the wheel (3) is lower than the suspension rigidity of the other wheels (3).

  According to the present invention, even if a failure is detected in both the left and right steering control means by making the suspension rigidity of the wheel in which the steering control means has failed lower than the suspension rigidity of the other wheels, the wheel The ground contact load is reduced and the influence on the vehicle behavior is reduced. Therefore, the influence on the vehicle behavior due to the failure of the left and right steering control means is suppressed.

  The second aspect of the invention also includes a steering control means (rear wheel toe angle varying mechanism 6) provided on at least one of the left and right front wheels (3f) and the left and right rear wheels (3r), the left and right front wheels (3f), and the left and right rear wheels. Steering having suspension stroke control means (a damping force variable damper 4 and an active stabilizer 8) provided on at least one of the wheels (3r) and a failure detection means (34) for detecting a failure of the steering control means (6). When the failure of the at least one steering control means (6) is detected by the failure detection means (34) in the controlled vehicle (V), the suspension control means (4, 8) has the steering control means (6). ) The suspension stroke is changed so that the ground contact load of the failed wheel (3) is reduced.

  According to the present invention, at least by changing the suspension stroke so that the ground contact load of the wheel in which the steering control unit has failed is reduced, that is, by reducing the influence on the vehicle behavior of the wheel in which the steering control unit has failed. When a failure of one steering control means is detected, the influence on the vehicle behavior can be suppressed according to the traveling state, and the behavior can be stabilized.

  According to the present invention, when the steering control means fails and the vehicle behavior cannot be improved, the suspension rigidity control means or the suspension stroke control means reduces the influence of the wheel on which the steering control means has failed on the vehicle behavior. The vehicle behavior can be stabilized.

It is a top view which shows schematic structure of the motor vehicle which concerns on embodiment. It is a block diagram which shows schematic structure of the motor vehicle which concerns on embodiment. It is a flowchart of the various control processing which concerns on embodiment.

  Hereinafter, a vehicle behavior control apparatus according to an embodiment will be described in detail with reference to the drawings. First, a schematic configuration of a four-wheel steered vehicle (hereinafter simply referred to as a vehicle V) equipped with a vehicle behavior control device will be described with reference to FIG. In the description, for the four wheels and members disposed therewith, that is, tires, suspensions, and the like, subscripts indicating front, rear, left, and right are attached to the numerals, respectively, for example, left front wheel 3fl, right front wheel 3fr. The left rear wheel 3rl and the right rear wheel 3rr are referred to as the wheel 3, the rear wheel 3r, etc.

  As shown in FIG. 1, a vehicle body 1 of an automobile V has wheels 3 with tires 2 mounted on the front, rear, left, and right. These wheels 3 are knuckle, suspension arm, spring, variable damping force damper (hereinafter referred to as “damper force damper”). It is suspended on the vehicle body 1 by a suspension 5 composed of a damper 4.

  In the automobile V, the left and right front wheels 3fl and 3fr are directly steered via the rack and pinion mechanism by the steering of the steering wheel 19 by the driver. In addition, the vehicle V can change the rear wheel toe angle by individually changing the rear wheel toe angle by extending and retracting the left and right steering actuators 7l and 7r interposed between the vehicle body 1 and the rear wheel knuckle. Mechanisms 6l and 6r are provided. Further, the front suspension 5f and the rear suspension 5r of the vehicle V are driven by stabilizer actuators 9f and 9r to change the front suspension rigidity and the rear suspension rigidity, respectively (hereinafter simply referred to as stabilizers 8f and 8r). Is provided.

  The vehicle V includes an ECU (Electronic Control Unit) 20 that drives and controls the left and right steering actuators 7l and 7r, the dampers 4fl to 4rr, the front and rear stabilizer actuators 9f and 9r, and the like.

  The damper 4 is a telescopic type using MRF (Magneto-Rheological Fluid) as a working fluid, and the ECU 20 controls the supply current to the magnetic fluid valve incorporated in the piston, so that the damping force is not present. Change in steps and instantly. The steering actuator 7 is a direct acting type composed of a DC motor, a speed reducer, and a feed screw mechanism, and the left and right rear wheels 3rl and 3rr are independently steered by the ECU 20 controlling the supply current to the DC motor. To do. The stabilizer actuator 9 is provided so as to connect the left and right stabilizer halves to an intermediate portion of the stabilizer 8 extending in the vehicle width direction, and includes a DC motor and a speed reducer. The ECU 20 supplies the DC motor to the DC motor. By controlling the current, a torsion angle is given between the left and right stabilizer halves in accordance with the roll direction to change the suspension rigidity in a stepless manner.

  In the automobile V, a steering angle sensor 10 for detecting the steering angle of the steering wheel 19, a vehicle speed sensor 11 for detecting the vehicle speed, a lateral G sensor 12 for detecting lateral acceleration, a longitudinal G sensor 13 for detecting longitudinal acceleration, and a yaw rate are detected. A yaw rate sensor 14 or the like that is installed at a proper position of the vehicle body 1, a vertical G sensor 15 that detects vertical acceleration of the vehicle body near the wheel house, and a stroke sensor 16 (not shown) that detects the stroke speed of the damper 4. Is installed for each wheel 3. Further, the steering actuator 7 is provided with position sensors 17l and 17r (not shown) for detecting the operation amounts (that is, the actual toe angles of the left and right rear wheels 3rl and 3rr), respectively. Twist angle sensors 18f and 18r (not shown) for detecting the twist angle between the stabilizer halves are respectively installed.

  As shown in FIG. 2, the ECU 20 includes a CPU, a ROM, a RAM, peripheral circuits, input / output interfaces, various drivers, and the like, via a communication line (CAN (Controller Area Network in this embodiment)). The sensors 10 to 18, the damper 4, the steering actuator 7, the stabilizer actuator 9 and the like are connected. The ECU 20 includes an input interface 21 to which detection signals of the sensors 10 to 18 are input, a rear wheel toe angle control unit 30 that performs drive control of the steering actuator 7, and a failure detection unit that detects a failure of the rear wheel toe angle variable mechanism 6. 34, from the damping force control unit 40 that controls the damping force of the damper 4, the roll stiffness control unit 50 that controls the drive of the stabilizer actuator 9, the rear wheel toe angle control unit 30, the damping force control unit 40, and the roll stiffness control unit 50. And an output interface 22 provided for output of the drive current.

  The rear wheel toe angle control unit 30 sets a reference yaw rate based on detection signals of the steering angle sensor 10 and the vehicle speed sensor 11 and sets a target rear wheel toe angle for realizing the reference yaw rate. 31, a target rear wheel toe angle correction unit 32 that corrects the target rear wheel toe angle set by the target rear wheel toe angle setting unit 31 when a failure signal is received from the failure detection unit 34, a target rear wheel toe angle and position A drive current output unit 33 is provided that sets a target current of the steering actuator 7 based on a difference from the actual rear wheel toe angle input from the sensor 17 and outputs a drive current of the steering actuator 7 based on the target current.

  Specifically, the target rear wheel toe angle setting unit 31 decelerates the target rear wheel toe angle to toe-out during acceleration based on the motion state of the vehicle grasped by various sensors in order to improve the steering stability of the automobile V. Sometimes the target rear wheel toe angle is set to toe-in, the target rear wheel toe angle is in phase with the front wheel 3f when turning at a speed higher than the predetermined vehicle speed, and the target rear wheel toe angle is set at the lower speed than the predetermined vehicle speed. The corner is set in reverse phase with the front wheel 3f.

  The failure detection unit 34 monitors the drive current output from the drive current output unit 33 and the actual rear wheel toe angle input from the position sensor 17, detects a failure of the steering actuator 7 or a failure of the position sensor 17, and When either or both of the left and right steering actuators 7 become uncontrollable and become locked, a failure signal is output according to the failure state of the left and right rear wheel toe angle variable mechanism 6.

  The damping force control unit 40 receives a failure signal from the target damping force setting unit 41 that sets the target damping force of each of the dampers 4fl to 4rr based on the detection signals of the sensors 10 to 15 and the failure detection unit 34. A target damping force correction unit 42 that corrects the target damping force set by the force setting unit 41, sets a target current of the damper 4 based on the target damping force and the stroke speed, and outputs a driving current of the damper 4 based on the target current The drive current output part 43 which performs is provided.

  The roll stiffness controller 50 estimates the roll moment acting on the vehicle body 1 based on the detection signal of the lateral G sensor 12, and when this roll moment is greater than or equal to a reference value, an anti-roll moment that cancels the roll moment exceeding the reference value is detected. A target roll stiffness setting unit 51 that sets a target roll stiffness (twist angle) for generation, and a target that corrects the target roll stiffness set by the target roll stiffness setup unit 51 when a failure signal is received from the failure detection unit 34 A drive current that sets the target current of the stabilizer actuator 9 based on the difference between the roll stiffness correction unit 52, the target roll stiffness and the actual twist angle input from the twist angle sensor 18, and outputs the drive current of the stabilizer actuator 9 based on the target current. An output unit 53 is provided.

  Next, with reference to FIG. 3, processing procedures for various controls of the steering control vehicle according to the present embodiment will be described. When the automobile V starts driving, the ECU 20 executes the following control with a predetermined control interval (for example, 2 ms).

  First, the ECU 20 sets the target rear wheel toe angle of the left and right rear wheels 3r in the target rear wheel toe angle setting unit 31 (step S1). In setting the target rear wheel toe angle, the target rear wheel toe angle setting unit 31 determines the target rear wheel toe of the left and right rear wheels 3rl and 3rr from the target rear wheel toe angle map based on detection signals of the steering angle sensor 10 and the vehicle speed sensor 11. The corner is searched and this value is set as the target rear wheel toe angle.

  Next, the ECU 20 sets the front, rear, left and right target damping forces in the target damping force setting unit 41 (step S2). In setting the target damping force, the target damping force setting unit 41 determines the motion state of the vehicle V based on the detection signals of the sensors 10 to 15, and then determines the skyhook control value, the roll control value, and the pitch control from the determination result. A value is calculated for each wheel 3. Then, the target damping force setting unit 41 selects, from these three control values, a target damping force that has the same sign as the stroke speed direction of the damper 4 and the largest absolute value.

  Further, the ECU 20 sets the front and rear target roll stiffnesses in the target roll stiffness setting unit 51 (step S3). In setting the target roll stiffness, the target roll stiffness setting unit 51 estimates the roll moment acting on the vehicle body 1 based on the detection signal of the lateral G sensor 12, and when this roll moment is greater than or equal to a reference value, the target roll stiffness map The target roll stiffness (twist angle) of the front and rear suspensions 5 is retrieved from this, and this value is set as the target roll stiffness.

  Thereafter, in the target rear wheel toe angle correction unit 32, the target damping force correction unit 42, and the target roll stiffness correction unit 52, the ECU 20 outputs a failure signal of the steering actuator 7 or a failure signal of the position sensor 17 from the failure detection unit 34. It is determined whether or not (step S4). When the failure signal is not output (No), each of the correction units 32, 42, and 52 does not directly correct the target rear wheel toe angle, the target damping force, and the target roll rigidity set in Steps S1, SS2, and S3. This is output (step S8), and this process is terminated. Each target control value output in step S8 is converted into a target current in each drive current output unit 33, 43, 53, and is output as a drive current to the steering actuator 7, the damper 4 and the stabilizer actuator 9.

  On the other hand, when a failure signal is output in step S4 (Yes), the ECU 20 determines whether or not the steering actuator 7 is fixed on both the left and right sides in each correction unit 32, 42, 52 (step S5). When only one of the left and right steering actuators 7 is fixed (No), it is determined whether or not the left steering actuator 7 is fixed (step S9).

  When the steering actuator 7 is fixed on both the left and right sides (step S5: Yes), the ECU 20 greatly corrects the target damping force of the dampers 4fl and 4fr provided for the front wheel 3f in the target damping force correction unit 42 ( Step S6) Further, the target roll stiffness correction unit 52 corrects the target roll stiffness of the front stabilizer 8f to be high (Step S7), and outputs the corrected target damping force and target roll stiffness (Step S8). Exit.

  On the other hand, when the steering actuator 7 is fixed only on the left side (step S9: Yes), the target rear wheel toe angle correction unit 32 sets the right rear wheel toe angle to the same value as the left rear wheel toe angle (the right side should be toe-in). For example, the left side is also toe-in) (step S10), and the target damping force correction unit 42 corrects the target damping force of the left rear damper 4rl to be small (step S11). Then, the ECU 20 corrects the target roll stiffness of the front stabilizer 8f to be high in the target roll stiffness correction unit 52 (step S7), and outputs the corrected target rear wheel toe angle, target damping force, and target roll stiffness ( Step S8) This process ends.

  On the other hand, when the steering actuator 7 is fixed only on the right side (step S9: No), the target rear wheel toe angle correction unit 32 corrects the left rear wheel toe angle to the same value as the right rear wheel toe angle (step S12). ) In the target damping force correction unit 42, the target damping force of the right rear damper 4rl is corrected to be small (step S13). Then, the ECU 20 corrects the target roll stiffness of the front stabilizer 8f to be high in the target roll stiffness correction unit 52 (step S7), and outputs the corrected target rear wheel toe angle, target damping force, and target roll stiffness ( Step S8) This process ends.

  Thus, when the steering actuator 7 is fixed on both the left and right sides, the target damping force of the dampers 4fl and 4fr of the front wheel 3f is largely corrected in step S6, and the target roll rigidity of the front stabilizer 8f is corrected to be high in step S7. Thus, even when a roll moment is applied to the vehicle body, such as during turning, an increase in the ground load on the rear wheel 3r that has become impossible to steer is prevented, and the influence on the vehicle behavior is suppressed.

  Further, when only one of the left and right steering actuators 7 is fixed, the target rear wheel toe angle of the steering actuator 7 not fixed in step S10 or step S12 is set to the same value as the toe angle of the steering actuator 7 fixed. By correcting, the straight running stability of the automobile V is ensured. Further, by setting the target damping force of the damper 4 on the side to which the steering actuator 7 is fixed in step S11 or step S13 to be small, and correcting the target roll rigidity of the front stabilizer 8f to be high in step S7, the vehicle body 1 such as during turning traveling can be used. Even when a roll moment is applied to the vehicle, an increase in the ground load of the rear wheel 3r where steering is disabled is prevented, and the influence on the vehicle behavior is suppressed.

  Although description of specific embodiment is finished above, the aspect of the present invention is not limited to the above embodiment. For example, in the above embodiment, reference is made to the rear wheel steering control. However, if a steer-by-wire device, a variable gear ratio steering device, or the like is provided, the present invention can also be applied to front wheel steering control. Moreover, although the above embodiment is an application of the present invention to a vehicle equipped with a variable damping force damper, it can also be applied to a vehicle equipped with an active control type air suspension or hydropneumatic suspension as a suspension stroke control means. It is. When these suspension devices are used, the suspension length of the wheel 3 incapable of steering control is shortened (the vehicle height is lowered) so that the ground load of the rear wheel 3r to which the steering actuator 7 is fixed becomes small, and the other wheels 3 The suspension length of the vehicle may be increased (the vehicle height is increased).

  Moreover, in the said embodiment, although one ECU20 is performing all the control, the form where ECU is each provided with respect to each control means may be sufficient. In such a case, the failure of the steering actuator 7 may be caused by the failure of the ECU, and other ECUs only need to control the damper 4 and the stabilizer 8. Furthermore, in the above embodiment, even when a failure is detected in both the left and right rear wheels 3r and when a failure is detected in one of the rear wheels 3r, the target roll rigidity of the front stabilizer 8f is corrected to be high. However, since the roll rigidity of the rear stabilizer 8r only needs to be relatively small, the target roll rigidity of the front stabilizer 8f is increased, the target roll rigidity of the rear stabilizer 8r is decreased, and the rear stabilizer 8r Only the target roll rigidity may be lowered. In addition, as long as it does not deviate from the gist of the present invention, the specific configuration of the automobile and the control device, the specific procedure of control, and the like can be appropriately changed.

1 body 3 wheel 4 damping force variable damper (suspension stroke control means)
5 Suspension 6 Rear wheel toe angle variable mechanism (steering control means)
7 Steering actuator 8 Active stabilizer (Suspension stiffness control means, Suspension stroke control means)
9 Stabilizer actuator 20 ECU
DESCRIPTION OF SYMBOLS 30 Rear wheel toe angle control part 32 Target rear wheel correction | amendment part 34 Failure detection part 40 Damping force control part 42 Target damping force correction part 50 Roll rigidity control part 52 Target roll rigidity correction part V Automobile

Claims (2)

Steering control means provided on at least one of the left and right front wheels and left and right rear wheels, suspension rigidity control means provided on at least one of the left and right front wheels and left and right rear wheels, and failure detection for detecting a failure of the steering control means A steering control vehicle having means,
When a failure is detected in both the left and right steering control means by the failure detection means, the suspension rigidity control means makes the suspension rigidity of the wheel in which the steering control means has failed lower than the suspension rigidity of other wheels. A steering control vehicle. Steering control means provided on at least one of the left and right front wheels and left and right rear wheels, suspension stroke control means provided on at least one of the left and right front wheels and left and right rear wheels, and failure detection for detecting a failure of the steering control means A steering control vehicle having means,
When a failure of at least one steering control unit is detected by the failure detection unit, the suspension stroke control unit changes the suspension stroke so that a ground contact load of a wheel in which the steering control unit has failed is reduced. Steering control vehicle.

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