A fault-tolerant steer-by-wire system based on angular position estimation

Abstract

While steer-by-wire (SBW) systems benefit from improved performance and comfort, they require a large number of sensors impacting whole system reliability. In order to address this challenge fault tolerance property against sensor faults has to be improved. Application of redundancy for the sensors is the best solution proposed so far. This paper proposes a novel solution of analytical redundancy based on various position estimation methods for both electrical motor and steering wheel position sensors. Three different estimation techniques including extended programmable cascaded low-pass filter (EPCLPF), stator flux linkage estimator using stator currents, as well as stator flux linkage estimator using stator voltages are proposed for this purpose. The faulty sensors are recognized using a voting technique in which a comparison between the sensors’ outputs with the estimated values is made. In this way, the SBW system reliability is highly improved with no additional cost and space. Simulation and experimental results are presented to confirm the presented fault tolerant SBW system capabilities.