Deutsche Forschungsanstalt Fur Luft-und Raumfahrt E.v.

Jurgen Ackermann

To support the driver of a road vehicle, a yaw velocity r (in radian/s) around a vertical axis is measured, a driving speed v.sub.x (in m/s) is determined, an acceleration a.sub.x (in m/s.sup.2) in the driving direction is measured, a lateral acceleration is measured at two randomly selected locations at a distance of l.sub.a as a.sub.y1 (in m/s.sup.2, front) and a.sub.y2 (m/s.sup.2, rear), a steering wheel angle .delta..sub.H is measured at the vehicle steering column with a potentiometer, a vehicle wheel angle .delta..sub.L =.delta..sub.H /i.sub.L commanded by the driver is computed, a variable angle .beta..sub.F at the front axis is computed, and these measured parameters are used to calculate, in a microprocessor, according to the equations (4, 20 and 21), an additional steering angle .delta..sub.C, whose addition to the vehicle wheel angle .delta..sub.L commanded by the driver results in the overall wheel angle .delta..sub.F =.delta..sub.L +.delta..sub.C.

Method of correcting steering of a road driven vehicle

A control system for steering a road vehicle having front-wheel and rear-wheel steering, comprising a wheel base l (in m), a rear cornering stiffness c.sub.h (in N/rad), a center of gravity distance l.sub.v (in m) from the front axle and a mass m (in kg) and provided with a decoupled control circuit, a predetermined yaw damping D.sub.G is adjusted according to a damping parameter ##EQU1## via the steering of the rear wheels through an angle .delta..sub.h (in rad). Herewith the yaw rate r (in rad/s), travelling velocity v (in m/s) and steering wheel angle .delta..sub.L (in rad) are measured and the angle .delta..sub.h =(l/v-k.sub.D) (w.sub.h -r) is calculated by a microprocessor, whereby w.sub.h is formed as command variable from the measured steering wheel angle (.delta..sub.L) by a prefilter (F.sub.h) associated with the rear-wheel steering.

Control system for steering a road vehicle having both front-wheel

A steering system for a road vehicle with front-wheel steering employs microprocessor integrating feedback of the vehicle yaw rate to the front-wheel steering actuator so as to decouple the yaw movement from the lateral movement of the front axle. Sensors measure vehicle speed, yaw rate (by gyroscope), lateral front axle acceleration (by acceleromether at the front axle), and the angle at which the driver holds the steering wheel. The microprocessor controls the front steering actuator according to a formula whose dependent quantities include the sensor outputs, fixed vehicle parameters (such as wheel base), and a preselected time constant. The vehicle's handling changes when the time constant is varied.

Method of steering a road vehicle with front-wheel steering

A method of steering road vehicles having front-wheel and rear-wheel steering is provided in which by an integrating feedback of a measured yaw rate signal to the front-wheel steering the yaw motion is decoupled from the lateral motion of the front axle, the problem of steering thereby being split into two subproblems to be solved separately, that is into a lateral track guiding of the front axle by a signal which a driver generates with the steering wheel, and into an automatic control of the yaw motion, and the eigenvalues of the yaw motion can be shifted as desired by feedback of the measured yaw rate signal to the rear-wheel steering in such a manner that the choice of the yaw eigenvalues has no influence on the steering transfer function from the steering wheel to the lateral motion of the front axle. When employing the steering method according to the invention the driver no longer has to worry at all about the yaw motion of his vehicle; it is stable. Furthermore, via the rear-wheel steering eigenvalues of the yaw motion can be fixed as desired in adaption to the desired driving mode, such as sporting or comfortable.

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Herrsching, Germany

Jurgen Ackermann