Fail-operational auxiliary steering system

Electronic hydraulic vehicle steering system with permanent maintained steering. Vehicles with a big influence of the rear axle steering position on the vehicle direction often demand for an active steering throughout the entire speed range.

Moreover, a common safety strategy with a passive failsafe mode is not sufficiant in many applications. EHLA® FAILOP provides highest availability by offering an entirely redundant architecture and is the solution for long-framed mobile cranes or multi-articulated buses.

EHLA® FAILOP is often combined with fail-safe systems or AGV applications. It offers the complete function range known from the fail-safe systems.

Fail-operational Auxiliary Steering System for the Van Hool Exquicity

One of the most challenging applications in the range of auxiliary steering systems is the articulated bus. Common fail-safe systems are limited for these vehicles. The risk analysis leads to a requirement for a SIL3 system (IEC61508) and the vehicle design does not allow any shut-down or centring measure in the case of a system failure as the driving behaviour of the trailer is massively affected or even a mechanic defect of the articulation may be provoked. Conclusively a fail-operational system is required.

MOBIL ELEKTRONIK has been working for more than 10 years in this field. This experience was transferred to the sophisticated Van Hool Exquicity. Besides the steering system the demand lies in the extensious system integration resulting from the hybrid drive chain. The system has been successfully approved from the TÜV Nord according ECE-R79 annex 6.