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In this paper, vibrations caused by brake judder are investigated theoretically and experimentally, in a vehicle. The experimental results of a road test are compared with the theoretical results obtained from a simplified model of the transfer path between the brake system and the steering wheel. Two accelerometers are used in order to measure the vibrations observed by the driver on the brake pedal and the steering wheel. The acquired signals are analyzed through waterfall analysis during the braking procedure. On the other hand, a similar condition is simulated by using a simplified model of transfer path between the brake disc and the steering wheel. Finally, a qualitative comparison is made between the results of simulations and experiments. The results show that both natural frequencies of the transfer path are observed in the experiments as well as simulations. The first two orders of the wheel are the dominant vibrations as stated in the literature.

This paper presents an algorithm for the detection of single and multiple misfires in internal combustion engines, using only the signal of the knock sensor. Several experiments were conducted on a four-cylinder engine to obtain the necessary signals in the healthy and faulty conditions. The faulty conditions were created by disconnecting the wires of the spark-plugs. The signal of the knock sensor is analyzed and the time-domain signals of different orders of engine vibrations are extracted using a Vold-Kalman filter (VKF). A set of statistical features were then extracted from the time-domain signals of each order. These features are representative of the engine condition. In the next step, the computed features were plotted for different states and are analyzed. Consequently, a criterion for identifying the engine misfire is obtained based on the extracted features.