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Heavy duty machines have become more electronically sophisticated and in-vehicle electronics are growing in number and complexity, keeping pace with technology advancements. New machines implements (both mounted or trailed) and machine automation, demand this evolution, and thus a new way of designing on-board Electronic Control Units (hereafter ECU) is required. Moreover, the connectivity between vehicles, often extended to World Wide Web, and machine control and Working Session Task Controllers demand to become really distributed and executed in real time. So, integrated control systems ask for more performing distributed controls over networks, in order to better manage the machine torque and power and in order to optimize the fuel consumption, as a function of power request.

Performance requests and machine automation, in conjunction with new regulations for commercial and heavy duty vehicles, represent a difficult challenge for machine design. Machine control systems complexity and functional safety regulation, are complex requirements to deal with in new machines design. The paper describes a steering system design, of a 6 wheeled agricultural front articulated self-propelled machine, that must comply with new regulations in terms of functional safety. The vehicle steering is driven by an electro-hydraulic system, totally controlled using electronics; the rear wheels are independently steered and controlled. This architecture requires a highly functional safety performance level. The safety analysis of the system lead to a required performance level whose compliance is a challenging task, due to the software quality required, and to the cost of a fully redundant hardware, on both electronics and hydraulics side.