Reliability Optimization And Development Based On ISO26262for Electronic Control Unit(ECU) Of Electronic Power Steering(EPS) System

Electric power steering (EPS) systems have been more and more widely used inmedium and large cars. But the development of EPS system in China is not as mature as indeveloped country. As a safety critical system, its safety and reliability are uttermostimportant. Software and hardware for automotive industry have to be as reliable as it isreasonably possible avoid human and property hazard, caused by its failure. That is whyindustry is constantly producing software development standards, which capture the bestpractices, recommendations and state-of-the art development technologies. Hencecompanies are constantly challenged by the need to align their current developmentprocesses with the upcoming standards like ISO26262standard.ISO26262adapted fromIEC61508provides a standard model as a reference process model for different phases ofproduct development. This paper aim to develop Electronic Power Steering(EPS) systembased on the ISO26262including software and hardware. Before the development of EPS,this dissertation discuss the standard criteria for C language and fault analysis based onISO26262are made for the later-stage development. Designed controller is divided into twolayer, the upper layer is mainly about basic control strategy, which mainly includesdifferential control of torque, selecting power-assisted characteristics and motorcompensation control. The lower layer is mainly about the underlying driver. For installingto the real vehicle, the ECU of EPS is developed in this paper, which includes the design ofsoftware and hardware. The design and development of software are mainly about thesoftware architecture of EPS and platform software, the design and development ofhardware are mainly about the basic units of prototype controller. The developed ECU ofEPS is tested by the real vehicle, the working conditions are pivot steering, steering handiness with low speed and returnable steering. The results of test show that the vehicleinstalled with the developed ECU of EPS can meet the requirement of expected steeringperformance. To reach the product level, this EPS system passed several reliability test.Finally, this dissertation presents a standard method for fault analysis based on theISO26262.