Controlling steer-by-wire steering apparatus

Abstract

A microprocessor system for a vehicle steer-by-wire steering apparatus, comprising: a hand wheel actuator controller, comprising first and second microprocessors, and arranged to provide control signals for a hand wheel actuator of the steering apparatus; a front axle actuator controller, comprising first and second microprocessors, and arranged to provide control signals for a front axle actuator of the steering apparatus; first and second private buses connecting the first microprocessor of the hand wheel actuator controller to the first microprocessor of the front axle actuator controller. The first private bus has a physical layer over which data can be transmitted with a first data link format and a second data link format different to the first data link layer format. The second private bus connects the second microprocessor of the hand wheel actuator controller to the second microprocessor of the front axle actuator controller. The second private bus comprises a physical layer over which data can be transmitted with either the first or second data link format. The microprocessor system is arranged to switch from the first state to the second state upon one of the first or second microprocessors of the hand wheel actuator controller or the front axle actuator controller determining that there is a fault on the first or second private bus.