Design and Testing of a Control System Based on STM X-Nucleo Development Boards for Detection and Wireless Transmission of Sensors Data Applied to a Single-Seat Formula SAE Car

The emerged potentials and opportunities in the electronics field are becoming greatly appreciated in a highly competitive environment such that of the mechanic/engine field. In fact, the electronic system integrated in a vehicle is playing an increasingly fundamental role, especially in the competition/races sector, such that related to the “Formula SAE” (Society of Automotive Engineers), a competition in which participating teams (eg the Salento Racing Team) compete in the design, construction and testing of prototype single-seater cars (Fig. 1(a)). In this research work, an electronic system able to monitor in real time and constantly principal parameters characterizing the moving vehicle and to transmit wirelessly the acquired data was realized [1, 2]. Different sensors, mounted on vehicle, exchange data with the data acquisition and wireless communication control unit (Fig. 1(b)): linear potentiometers in order to monitor the suspensions behavior, temperature transducers located inside the engine compartment, gyroscope/accelerometer for detecting the accelerations and the inclination angles in space (i.e. pitch, roll and yaw), one NTC thermistor for acquiring the cooling liquid temperature and Hall effect sensors for monitoring the vehicle speed and any slippage of the wheels [3]. Besides, the realized data acquisition board, shown in Figs 2a and 2b, is composed of a conditioning board, for adjusting the voltage value of signals provided by sensors in accordance to voltage values required by the STM-32 Nucleo F411RE development board, which processes received data and, by means of the DORJI DRF1278F WiFi radio module, sends them to the base station (Fig. 2c) [4]. A further component is the SPARKFUN CAN-BUS shield module employed for data storage on SD memory card and for establishing the communication between the STM board and the engine control unit which receives signals from Hall sensors and from the NTC thermistor. The developed firmware (flow chart shown in Fig. 3), installed on STM32F411RET6 microcontroller embedded on STM board, allows the reading of signals provided by sensors, the SPARKFUN CAN module management and wireless transmission data through DORJI WiFi module. In Fig. 4, graphs relative to the sent data to the base station, concerning the vehicle speed, suspensions behavior and cooling liquid temperature monitoring, are shown. As reported in the graphs, data are correctly received by the base station and they show accordance between themselves, confirming, in this way, the proper functioning of the developed data acquisition and wireless transmission systems.