Hardware-in-the-Loop Testing of Engine Control Units - A Technical Survey

Due to tougher legislation on exhaust emissions reduction and the consumer demand for more power and mobility and less fuel consumption, the functionality in today's engine management systems continues to grow. The electronic engine control units (ECUs) have to perform more control tasks using new sensors and actuators, along with the corresponding self-diagnostics (OBD, on-board diagnosis).
All this leads to continuously increasing demands on automated hardware-in-the-loop (HIL) test systems. HIL technology has advanced in parallel to the ECUs, and is today an indispensable tool for developing automotive electronics. This paper therefore aims to provide a comprehensive and state-of-the-art survey of HIL test systems for engine controllers.
First of all, a brief introduction to the ECU's functionality is given. Then the sensor and actuator interfaces are described in detail together with the corresponding interfaces of the HIL simulator, and both hardware and software aspects are discussed. There follows a description of the real-time engine simulation models which are needed to close the control loop between the ECU and the HIL simulator. Finally, some typical HIL system configurations are shown to demonstrate today's breadth of applications. The last section looks at future development steps in HIL technology, necessitated by the current enhancements to ECUs.