Abstract:

Torque control is the core function of the vehicle control unit （VCU）， which is crucial to ensure its safety. Therefore， for the problem of unexpected torque output anomalies in VCU， functional safety analysis is conducted in this paper based on the ISO 26262 standards， and a torque control three-layer monitoring strategy is proposed based on the EGAS architecture. Firstly， based on the definition of VCU items， the level of automotive safety integrity and safety objectives are determined through hazard analysis and risk assessment. Secondly， the fault tree analysis method is used to derive functional safety requirements and technical safety requirements. Once again， a functional safety mechanism based on the AURIX TC275 three-core main control chip and TLF35584 power monitoring chip is designed for safety objectives. In addition， CPU resources are allocated through a three-layer monitoring strategy to achieve the separation of basic torque control functions and monitoring functions. Finally， processor in loop testing is conducted， including UDE debugging， UDS diagnosis， and TLF35584 security state control testing. The results indicate that this three-layer monitoring strategy can achieve the basic function of VCU torque control and enter a safe state in a timely manner in case of faults， thereby achieving safety goals.

Key words: functional safety, vehicle control unit, torque control, three level monitoring