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Abstract: ISO 26262: Experience Applying Part 3 To An In-Wheel Electric Motor

This paper presents a case study that applies ISO 26262 Part 3 to the hazard analysis of an in-wheel electric motor. It describes the activities undertaken, their mapping onto the Standard, and discusses the limits and strengths of the analysis and possible alternative approaches

ISO 26262: Experience Applying Part 3 To An In-Wheel Electric Motor – Introduction

ISO 26262 Part 3  mandates a process for evaluating the functional hazards associated with electrical and electronic systems and components fitted to road going vehicles of up to 3500 kg. While the processes detailed within are perhaps well suited to the needs and capabilities of large vehicle manufacturers and established suppliers, the capacity of smaller organisations to apply ISO 26262 and to bring to market a  novel device is less well understood. In this paper the authors document the actual process used to develop the Functional Safety Concept (FSC) for an in-wheel electric motor and compares this with the idealised process presented in ISO 26262. We also compare our process with the options that are possibly available to larger organisations. Using the terminology defined in ISO 26262, the ―item‖ under analysis is an in-wheel electric motor capable of generating over 800Nm of torque for extended periods of time. Unlike a number of similar systems this device incorporates all the high voltage and control electronics within the hub of the wheel, outboard of the vehicle‘s suspension. It should  be noted that even though the development is not being performed by a major OEM the analysis we perform is of an ―item‖ rather than a ―Safety Element out of Context‖ (SEooC). This approach was chosen because although the ―item‖ is not targeted at a specific vehicle programme, it does directly influence the safety of the vehicle; as the item combines elements of a drive-by-wire engine, a brake system and a differential. Indeed it is difficult to conceive how an analysis of the ―item‖ could be performed out of context.