Slip Controller Development for an Electric 4WD Formula Student Race Car

Slip Control is a common topic on high performance race cars vehicle dynamics. With respect to common passengers cars, in this particular application, the main goal is focused on the vehicle dynamic performances improvement. This can be achieved enhancing the vehicle control system capability to properly deliver the right amount of torque to the tires in every working condition. The subject of this analysis is the Formula Student Squadra Corse PoliTO 4-Wheel-Drive electric race car Slip Controller. The prototype is embedded with 4 independently controlled electric motors, which drive one wheel each, giving very high flexibility to the torque delivery. Due to the non-linearity of the tire contact patch interaction with the ground, a proper Controller should be implemented. This work aims to propose a solution to improve the vehicle slip control with the development of a Fuzzy Logic Controller. This can be able to improve the non-linearities control, not relying on a model-based controller that would require higher data, sensors and validations. This makes the Fuzzy Logic Controller an interesting and cost effective solution. A PI Slip Controller is also proposed as a benchmark, being the most simple, diffused and yet a quite effective solution, despite its linear approach. The different solutions are implemented and tested in a MATLAB Simulink and VI-grade CarRealTime co-simulation environment. The pros and cons of this approach are discussed in the analysis. Results are discussed through the project Key Performance Indicators. The selected KPIs embrace basic physics, vehicle dynamics and lap-time simulation aspects. Since the analysis is focused on the behaviour of the controller on different working conditions, each of them is characterized by different key aspects. Finally, overall results of the vehicle in normal track drive situations, represented by the different Formula Student Events, are also analysed.