Accurate information of the absolute speed of a vehicle, when available, can be vital in simplifying the control laws of an anti-lock braking system (ABS) and traction control system (TCS). A current speedometer method for measuring the speed of a vehicle is to multiply the measured wheel revolution rate by the wheel radius. The approach often includes abrupt unpredictable errors due to the slip and skid of wheels and a biased error due to the steady state slip. These errors are sources of difficulty in the implementation of an ABS that is based on the absolute speed of the vehicle. This paper describes an accurate rule-based Kalman filtering technique for estimating the absolute speed of a vehicle. The enhanced accuracy is achieved by employing an additional accelerometer to complement the wheel-speed based speedometer. The accelerometer measures the acceleration of the vehicle in its forward direction but may be affected by high frequency noise. The proposed sensing technique employs the extended Kalman filter to reduce the high frequency noises in the acceleration measurement and the biased error coming from the wheel speed measurement. Furthermore, the authors incorporate a rule-based strategy that switches the values of the Kalman filter coefficients to compensate for abrupt nonstationary errors in the measurement. These rules are developed from some basic understandings. For example, when skid or slip occurs, the wheel speed measurement may be quite erroneous; therefore, a heavier reliance would be placed on the acceleration measurements over those of the wheel speed. Experiments in a test course were carried out to verify the proposed strategy and prove that it can accurately estimate the absolute speed even when wheel slip or skid occurs.
Absolute speed measurement of vehicles from noisy acceleration and erroneous wheel speed
Messung der absoluten Fahrzeuggeschwindigkeit aus dem Beschleunigungsgeräusch und falscher Raddrehzahl
Intelligent Vehicles, Symposium, 1993 ; 271-276
1993
6 Seiten, 7 Bilder, 6 Quellen
Conference paper
English
Absolute Speed Measurement of Vehicles from Noisy Acceleration and Erroneous Wheel Speed
British Library Conference Proceedings | 1993
|SAE Technical Papers | 1992
|Automotive engineering | 1992
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