Abstract
The primary way to control a motorcycle is the steering torque exerted by the rider on the handlebars. Basic steering properties of motorcycle can be evaluated in steady turning conditions. These properties can be also related to handling and stability of vehicle: if low steering torque is required on steady state cornering, the driver feels that the vehicle is maneuverable. Furthermore, if the steering torque has opposite sign with respect to the steering angle, the capsize mode is rather stable.
This paper deals with the effect of motorcycle geometric and inertial properties on steering torque in steady turning. The analysis is carried out by means of numerical simulations and experimental tests. Numerical simulations are carried out by means of a 11 d.o.f. multi-body model. Experimental tests are performed on a sport motorcycle equipped with instrumented handlebars and gyroscope transducers. The numerical results are compared to experimental data, obtaining good agreement. After this validation of the multi-body model, several numerical simulations are carried out in order to understand the influence of some geometric (like trail, castor angle) and inertial (like mass gravity center position, inertia moment) properties of the motorcycle on the steering torque. Steering torque is represented by contour plots, as a function of path curvature and forward speed. Finally, some dynamic simulations are carried out in order to examine the effect of the same parameters on the transient from straight running to steady turning.