JP2007246058A - Maneuverability control device of automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a maneuverability control device, securing turning stability when an active suspension device breaks down. <P>SOLUTION: In an automobile including an active suspension device driven by an actuator and provided at least on a rear wheel, this maneuverability control device includes: a turning characteristic control means for controlling at least either the braking force or the driving force to restrain an under steering tendency; and a failure diagnosis means for discriminating the presence/absence of abnormality of the active suspension device, wherein when the active suspension is decided to be abnormal, the under steering restraining force is made larger than normal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a controllability control device for a vehicle, and more particularly to a controllability control device suitable for a vehicle in which a rear wheel suspension is actively controlled.

In recent years, active suspension systems based on the Skyhook theory have been actively developed as suspensions for automobiles. In this active suspension system, the distance between the vehicle body and the road surface and the damping force of the damper are controlled in real time for each wheel according to the road surface condition and the amount of motion state of the vehicle. In addition to being suppressed, a good ride comfort can be obtained, and at the same time, the grounding property of the tire can be improved and high steering stability and driving / braking performance can be obtained (see Patent Document 1).
JP 2001-328414 A

  However, in a vehicle equipped with the above-described active suspension device, the weight of the vehicle body is supported by mechanical spring means so that the minimum maneuverability can be ensured even when the actuator or the electronic control unit breaks down. The frictional force is set to act as a damping force. However, if the control is not applied, the damping force of the damper becomes the lowest, so that the roll rigidity during turning becomes the lowest and the tendency to understeer becomes inevitable.

  On the other hand, VSA (Vehicle Stability Assist) system that improves vehicle turning stability by appropriately controlling braking force for each wheel based on the standard yaw rate estimated from lateral acceleration, vehicle speed, and steering angle of steering wheel It is used for If understeering or oversteering during turning, the driver will deviate from the turning behavior intended by the driver. Therefore, when the degree of deviation exceeds a predetermined amount, the braking force of the left and right wheels is individually controlled by the independent braking device. By controlling this, the vehicle is controlled so that the stability of the vehicle is maintained.

  The inventors of the present application have paid attention to the understeer suppression control of the VSA system and have come to consider that the VSA system compensates for an excessive understeer tendency when the active suspension device fails.

  In view of the problems of the prior art and the inventor's knowledge, a main object of the present invention is to provide a maneuverability control device capable of ensuring turning stability even when an active suspension device fails. It is in.

  To achieve such an object, the present invention suppresses an understeer tendency by controlling at least one of braking force and driving force in an automobile in which an active suspension device driven by an actuator is provided at least on a rear wheel. It is assumed that it has a turning characteristic control means and a failure diagnosis means for determining the presence or absence of abnormality of the active suspension device, and when the active suspension device is judged to be abnormal, the understeer suppression effect is made larger than usual. .

  According to the present invention, when the active suspension device breaks down and the damping force of the damper decreases, the roll rigidity at the time of turning decreases and the understeering tendency increases, which is controlled by braking force or driving force. Therefore, even if the active suspension device fails, turning stability can be ensured.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows the overall configuration of an automobile to which a maneuverability control device according to the present invention is applied. The automobile 1 includes four wheels 3 on which tires 2 are mounted, and each wheel 3 is suspended on the vehicle body by an active suspension device 4 including an electric actuator. Each wheel 3 includes a brake device 5 and a wheel speed sensor 6.

  The automobile 1 includes an ECU (Electronic Control Unit) 7 that is a control subject of the active suspension system and the VSA system, a power supply control unit 8 that supplies electric power to an electric actuator of an active suspension device 4 that supports each wheel 3, and each brake device 5. A braking force control unit 9 that individually controls the hydraulic pressure to the vehicle and an EPS (Electric Power Steering: electric power steering) 11 that boosts the steering force applied to the steering wheel 10 and transmits it to the left and right front wheels. The automobile 1 further includes a lateral G sensor 12 that detects lateral acceleration, a yaw rate sensor 13 that detects yaw rate, a stroke sensor 14 that detects the vertical stroke of the suspension, a vertical G sensor 15 that detects vertical acceleration in the vicinity of the wheel house, and a steering wheel. A steering angle sensor 16 that detects the steering angle of the wheel 10 is provided.

  The ECU 7 includes a microcomputer, ROM, RAM, peripheral circuits, input / output interfaces, various drivers, and the like. The power supply control unit 8, the braking force control unit 9, the EPS 11, and the sensors 6 are connected via a communication line. 12 to 16 are connected.

  Next, the controllability control system of the present invention will be described with reference to FIG. The control system includes a reference yaw rate calculation unit 17 that calculates an ideal yaw rate acting on the vehicle body at that time based on the output of the wheel speed sensor 6, the output of the lateral G sensor 12, and the output of the steering angle sensor 16. A yaw rate deviation calculating unit 18 for calculating the yaw rate deviation by comparing the reference yaw rate with the actual yaw rate detected from the yaw rate sensor 13, and a predetermined reference value for determining the degree of oversteer and understeer by comparing with the yaw rate deviation. , A gain setting unit 20 for generating an appropriate braking force command value corresponding to the degree of oversteer and understeer, and the left and right brake devices 5 so that the turning characteristic is neutral. The control command value output unit 21 generates a braking force command value to be applied to the vehicle.

  When the fault diagnosis circuit 22 of the ECU 7 diagnoses that the control related to the active suspension system is abnormal, the active suspension control is canceled, and the suspension characteristic becomes the basic motion characteristic determined by the mechanical characteristic. This abnormality occurrence signal is input to the gain setting unit 20, and the control command value is set so that the understeer suppression command value in the VSA control is higher than normal. Thereby, it is compensated that the tendency of understeering due to the fact that the active suspension device 4 is not controlled is increased, and the steering stability during turning is ensured.

  The process for making the understeer suppression command value higher than normal is not limited to increasing the gain of the control command value, but the threshold value for determining the degree of understeer is lowered, or the understeer suppression value is compared with the actual yaw rate. A method of changing the standard yaw rate that is a reference for determining the degree may be used, and an appropriate control can be performed by appropriately combining these methods.

  Furthermore, understeer suppression control can be performed not only by controlling the left and right braking forces differently, but also by varying the left and right driving force distributions.

It is a control system block diagram of the motor vehicle to which this invention is applied. It is a block diagram concerning control of this invention apparatus.

Explanation of symbols

4 Active Suspension Device 5 Brake Device 6 Wheel Speed Sensor 12 Lateral G Sensor 13 Yaw Rate Sensor 16 Steering Angle Sensor 20 Gain Setting Unit 22 Fault Diagnosis Circuit

Claims (1)

An active suspension device driven by an actuator is an automobile maneuverability control device provided at least on the rear wheel,
A turning characteristic control unit that controls at least one of a braking force and a driving force to suppress an understeer tendency, and a failure diagnosis unit that determines whether the active suspension device is abnormal; the active suspension device is abnormal When it is determined, the controllability control device for an automobile characterized in that the understeer suppression effect of the turning characteristic control means is made larger than normal.

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