Enhancing Reliability of Drive-by-Wire Control Units by Fault Compensation using Data Fusion

As future drive-by-wire systems have no mechanical fallback level, the increased safety requirements need to be met by software-based solutions. The task of the software is to provide services in the field of fault detection and compensation as well as control of redundant hardware structures. Particularly the implementation of fault detection and error correction avoids fatal output of drive-by-wire control units caused by erroneous input signals.

This article describes the implementation of a module compensating faults in the input signals of a vehicle function, which controls the longitudinal dynamics of a truck. The error correction is achieved by means of data fusion. Sensing units consisting of the sensor as well as the preprocessing unit often are provided by external suppliers. In some cases information regarding the characteristics of their output data written on the CAN bus is not available. In order to avoid the time-consuming and costly acquisition of this information a method is presented allowing for the estimation of the data quality. This approach is based on the analysis of the time response, the information content and the estimation of the measurement noise variance of the CAN-data. The quality measures are incorporated in a fuzzy-weighted aggregation of the signals and a subsequent filtering with an information filter.

This article describes how data fusion can be used profitably for the error compensation of fault-tolerant control systems. The estimation method of data characteristics introduced in this paper allows for a substitution of the erroneous signals with a marginal loss in quality. Additionally in the fault free case an improvement of the data quality regarding noise and dynamics can be achieved.