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The transfer functions of a motorcycle, especially that between roll angle and steering torque, qualify inputoutput characteristics — that is, motion produced as a function of steering torque — and are closely related to ease of use and handling. This paper describes the measurement of the transfer functions of a typical sports motorcycle, resulting from data collected in slalom tests. These functions are then compared to analytical transfer functions derived from known models in the literature. The comparison shows fair to good agreement. Lastly, the formation of steering torque is analysed and the observed transfer functions are interpreted in this framework. It is shown that gyroscopic effects are mostly responsible for the lag between steering torque and roll angle, and that there is a velocity for which the various terms that combine to form steering torque cancel each other out, yielding a 'maximum gain condition' for torque to roll transfer function which drivers rated 'good handling'. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach to the assessment of the manoeuvrability of vehicles which is not based on the simulation of open-loop manoeuvres, nor does it rely on the modelling of the driver as a control system. Instead, the essence of the method is the solution of a two-point optimal control boundary value problem, in which a vehicle, subject to physical constraints like tyre adherence and road borders, among others, is required to go between given initial and final positions as fast as possible. The control inputs — i.e., the driver's actions — that make the vehicle move between the two states in the most efficient way are found as a part of the solution procedure and represent the actions of a sort of ideal, perfect driver. The resulting motion is called the optimal manoeuvre and, besides being the most efficient way that the given vehicle has for travelling between the two points according to the chosen optimal criterion, may be taken as a reference for meaningful comparisons with other vehicles. The value of the penalty function, used to define the optimal condition occurring at the optimal manoeuvre, may be taken as a measure of manoeuvrability or handling. With this approach the manoeuvrability properties are established as intrinsic to the vehicle, being defined with respect to an ideal perfect driver. Some possible forms of the penalty function, which means slightly different concepts of manoeuvrability and handling, are discussed. In the end, the case of motorcycles and some examples of optimal manoeuvres are given. [ABSTRACT FROM AUTHOR]