Method and device for stabilizing a vehicle combination

Abstract

Method and Device for Stabilizing a Car-Trailer Combination A method and device for stabilizing a car-trailer combination, including a towing vehicle and a trailer moved by the towing vehicle, is disclosed. The rolling motions of the towing vehicle are monitored and measures that stabilize driving are preformed upon detection of an actual or expected unstable driving condition of the towing vehicle or the car-trailer combination. In order to insure a proper intervention, the yaw velocity of the towing vehicle or the car-trailer combination is detected and the measures that stabilize driving conditions are controlled dependent upon the detected yaw velocity.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and a device for stabilizing a car-trailer combination, including a towing vehicle and a trailer moved by the towing vehicle, wherein the towing vehicle is monitored in terms of rolling motions and measures that stabilize driving are taken upon the detection of an actual or expected unstable driving performance of the towing vehicle or the car-trailer combination. BACKGROUND OF THE INVENTION [0002] The present method aims at detecting and controlling the instabilities of car-trailer combinations (motor vehicle with trailer), especially of combinations consisting of a passenger car, pickup truck or sport-utility vehicle and any trailers desired, in particular caravans, before driving conditions are encountered during which the driver can no longer maintain control of the vehicle. These unstable conditions involve the rolling motions known with car-trailer combinations and the anti-phase build-up process between the towi...

AI Technical Summary

Benefits of technology

[0014] An object of the invention is to provide a method and a device permitting the reliable detection of unstable driving performance.

[0016] Advantageously, the method allows for reliably detecting snaking car-trailer combinations, in particular passenger car / trailer combinations. In this method, a differential value Δ{dot over (ψ)} is generated from the measured yaw rate and the model-based reference yaw rate, which value is representative of the deviation of the vehicle from the track predetermined by the steering wheel position. Because this differential value represents only the deviation from the desired track, monitoring the differential value ensures the judgment of oscillations independently of a curved track passed e.g. due to a steering angle. Preferably, the differential value is filtered in a low-pass filter in order to cut off signal peaks triggered by the detection of coefficients of friction. Spurious detections and, thus, faulty control activations are avoided in addition. The method and the device favorably require only a sensor system provided in an Electronic Stability Program (ESP) driving stability control.

[0017] In this arrangement, an actuating signal for an electric motor of a hydraulic pump producing a brake pressure and, hence, actuating the wheel brake of the towing vehicle or the trailer is generated by way of the data measured by a yaw rate sensor, derived in an ESP driving dynamics control operation and logically combined with the ESP control strategy. In this data the data of a motor vehicle can be included. It is possible alternatively or additionally to drive an actuator of an overriding steering system. By applying equal or different brake pressure to one wheel of preferably the towing vehicle or to all wheels of the towing vehicle corresponding to an ESP control strategy, it is possible to correct the instabilities of the car-trailer combination detected by sensors and to reduce the possibly existing excessive transverse dynamics of the car-trailer combination by reducing the vehicle speed and / or the lateral forces at one wheel by means of increased brake pressure and / or the increase in the longitudinal forces.

[0021] Further, it is advantageous that the threshold value of each half wave representative of the amplitude is determined at least in dependence on quantities that represent the velocity of the towing vehicle or the car-trailer combination or the trailer. It is arranged for that with quantities describing a high speed, the threshold value is reached or exceeded at lower amplitudes than is the case with quantities describing a low speed.

Problems solved by technology

These unstable conditions involve the rolling motions known with car-trailer combinations and the anti-phase build-up process between the towing vehicle and the trailer as well as imminent roll-over conditions at too high lateral accelerations caused by obstacle avoidance maneuvers, lane changes, side wind, road irregularities and / or hasty steering maneuver requests by the driver.

It is problematic with this detection strategy that there are still other maneuvers generating similar variations of signals.

Thus, sprung-mass vibrations may be produced, e.g. during cornering with a constant steering angle, which also induce sinusoidal variations of lateral quantities.

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