Optimality Properties and Driver Input Parameterization for Trail-braking Cornering

In this work we present an analysis of rally-racing driving techniques using numerical optimization. We provide empirical guidelines for executing a Trail- Braking (TB) maneuver, one of the common cornering techniques used in rally-racing. These guidelines are verified via experimental data collected from TB maneuvers performed by an expert rally driver. We show that a TB maneuver can be generated as a special case of the minimum-time cornering problem subject to specific boundary conditions. We propose simple parameterizations of the driver's steering, throttle and braking commands that lead to an alternative formulation of the optimization problem with a reduced search space. We show that the proposed parametrization of the driver's commands can reproduce TB maneuvers along a variety of corner geometries, requiring only a small number of parameters.