Safety Standards for Steer-By-Wire Systems

Development of true Steer-by-Wire systems without a mechanical backup continues to progress in the marketplace. As with any vehicle safety-critical system, Steer-by-Wire system design must provide for uninterrupted, safe operation throughout the life of the vehicle. There are multiple approaches to achieve this objective, which can be different for various failure modes. When considering system safety of Steer-by-Wire systems, common topics of discussion include different failures modes unique to Steer-by-Wire, what constitutes a safe operating state, how long a vehicle should be allowed to operate when a next electrical component failure would lead to violation of a safety goal, and what vehicle operating conditions are acceptable as a safe state. Currently, answers to these questions vary significantly, with approaches and philosophies largely left to individual vehicle manufacturers. One way to improve this situation is to develop and acknowledge industry-wide safety standards. This paper presents several areas for consideration in establishing safety standards for vehicles equipped with true Steer-by-Wire systems and draws parallels to more familiar topics associated with Electric Power Steering. Initial recommendations are made for areas which would benefit from industry-wide consensus and establishment of standards to benefit OEM’s, suppliers, end consumers, and ultimately the entire industry.