Abstract
The present work compares simulated optimal manoeuvres of motorcycles with and without rider´s lateral lean movements. Aim is to assess the improvements and differences in driving styles when the rider is allowed to control the vehicle with the additional control of the torso movements. The "optimal" adjective refers to optimal control method, here used to find the perfect driver´s longitudinal controls: steering torque and lean motion (when allowed).
The optimal control theory yields the driving manoeuvres that best achieve a given objective (for example minimum lap time, safety criteria, etc.). No "driving rules" (differently than fuzzy logic or neural net approaches) have to be predefined: they naturally emerge from the optimality criterion and solution of control problem. Recently, it was shown how to include the driving styles and driver´s limitations in the optimality criterion by means of a small set of parameters, which can be obtained from experiments. The optimal manoeuvre approach guarantees that different vehicles (i.e. with different design parameters) are always driven according to their best, making it possible to compare and evaluate the influence of design parameters on the basis of vehicle intrinsic performance (manoeuvrability, considering the best driver possible), or as a whole system (handling, including different driving styles and physical limitations).
The algorithm used to solve the optimal control problem is based on an indirect method, which computes the solution of the two-point boundary value problem derived from the necessary condition of optimality. The solution is very accurate and can be obtained quite fast (e.g. a few minutes for a relative complex motorcycle model for a whole circuit lap). In this work the rider torso lateral movement is analysed. It is an additional control input that permits performance improvements, which are quantified. The focus is a first study on the understanding of the relative importance of the steering torque versus the rider´s upper body lateral movements on the motorcycle manoeuvring efficiency. In fact, it is known that a rider drives a motorcycle by applying a steering torque to the handlebar and by changing the body position with respect to the motorcycle. Even if the rider uses the steering torque as a primary control he is able to change the vehicle dynamics in transient phases of a manoeuvre with his upper body movements. Here it is shown how this capability let him anticipate the sequence of actions in manoeuvring.
Keywords - dynamic path planning, optimal control, motorcycle handling, rider movements, driving style