Design and development of a test instrument for steering wheel characterization in automotive safety tests. Wireless communication and CAN data analysis

This thesis activity is aimed at designing and building a prototype of an instrument for measuring the steering wheel angle and the steering wheel torque, with the vehicle stationary and in motion. The project was carried out at the Turin-based company AMET Srl. The instrument, called Electronic Level, must have an appropriate mechanical fixing system able to adapt to different types of steering wheels. It has intelligence on board that can be programmed for carrying out tests, storing data, processing CAN messages, and PC interfacing. The system consists of three components: the first one is the Electronic Level fixed to the steering wheel with an anchor in three or four points, applicable to guarantee a secure and deterministic fixing, such as avoiding damages to the steering wheel. The second component is an OBD (On-board Diagnostic) interface for the acquisition, directly from the CAN bus of the vehicle under test, of steering angle, steering torque (when available), vehicle speed, and VIN (Vehicle Identification Number). The last component is the software to be loaded on the ground station (i.e. the PC), equipped with a USB 2.0 or higher interface. During the preliminary design phase, it was decided to use a 9-axis IMU system, which includes accelerometer, gyroscope, and magnetometer sensors, useful to measure the steering wheel angle. The idea is to filter the values obtained from these sensors using adaptive filtering techniques, in order to have a measurement as precise as possible, compensating sensor errors; once the steering angle value is obtained, it is compared to the same value received from the CAN bus. This comparison is made possible by reading the CAN data of the vehicle, and by the wireless transmission of the values of interest between the two modules on board (the Electronic Level and the OBD component), adopting a communication protocol called ESP-NOW. Due to the lack of time, it was not possible to realize an effective solution for the torque measurement, the preliminary study on this will be used for future developments. The obtained results analyze the accuracy of the measured steering angle in different test conditions. As for future developments an effective anchoring system and a data filtering method based on the Extended Kalman Filter should be evaluated.