Fault tolerance steer-by-wire electrohydraulic system with haptic interface for articulated vehicles

The current advance in embedded computer control systems encourages the introduction of X-by-wire control systems in automotive applications as well as earth moving equipment applications. Steer-by-wire is one application of X-by-wire systems. A steer-by-wire vehicle is one step towards autonomous vehicles. This work focuses on earth moving articulated vehicles. Current state of art steering systems used in articulated vehicles are hydro-mechanical systems.;In this work a novel steering haptic interface using a semi-active force feedback device is proposed for application on off-road articulated vehicles. The interface used for both closed-loop steering position control and open-loop steering velocity control algorithms. The steering interface allows the introduction of corrective steering action in order to reduce the instability which occurs due to the time delay in closed-loop position control. A lab setup is designed to test the proposed haptic interface.;A fault tolerant steer-by-wire system is proposed with a primary and redundant electrohydraulic circuit. The system is controlled by two redundant embedded electronic control modules (ECM). Two main control algorithms are implemented to run on the ECM in real time, the steering control algorithm and the failure detection algorithm. A startup failure diagnostics runs at machine start up in order to test the electrohydraulic components of the primary and redundant circuit. Finite state machine (FSM) concept is used to design the fault handling algorithm for the component level and system level.