A Study on Motorcycle-Rider System Simulations

It is necessary to predict motorcycle performance at an early stage of development to minimize the period for designing, experimenting, and tuning. In order to do that, we have developed a motorcycle model with a mechanical dynamic simulation program. This model includes the bodies of a motorcycle, aerodynamic forces, tire forces, engine characteristics, simplified gear trains and driving chains, and rider operations. With this program, we have conducted motion simulation on steady state turn and disturbance response tests with two kinds of tire stiffness. We have also conducted experiment on the steady state turn and disturbance response tests to validate the program. In this paper, we analyze the results of the simulation and experiment. As a result, it is confirmed that the simulation results accord with the experimental results, and we have found that the steer angle and bank angle at the steady state turn depend on tire stiffness. The frequencies and damping ratios at the disturbance response tests are also affected by tire stiffness. We have also conducted simulations on disturbance response tests with different crankshaft rotating directions and found that the stability is affected by the direction. In this case, simulations are effective because these tests cannot easily be experimented.