Study on Weave Behavior Simulation of Motorcycles Considering Vibration Characteristics of Whole Body of Rider 2018-32-0052

In motorcycles, the mass difference between a vehicle and a rider is small and motions of a rider impose a great influence on the vehicle behaviors as a consequence. Therefore, dynamic properties of motorcycles should be evaluated not merely dealing with a vehicle but considering with a man-machine system. In the studies of a simulation for vehicle dynamics, various types of rider models have been proposed and it has already been reported that rider motions have a significant influence on the dynamic properties. However, the mechanism of the interaction between a rider and a vehicle has not been clarified yet. In our study, we focused on weave motion and constructed a full vehicle simulation model that can reflect the influences of the movements of the rider’s upper body and lower body. To construct the rider model, we first measured the vibrational characteristics of a human body using a vibration test bench. Based on the measured data, 26 degrees of freedom was determined as the relevant parameters. In addition, spring and damper characteristics of each part of a human body were identified. Using this rider model, a simulation was carried out applying the equivalent input as the pulse response test. The simulation results well represented those of actual vehicle running tests and it was confirmed that, in the weave mode, the rider’s body motion influences the phase difference between the steering angle and the roll motion of a vehicle. Furthermore, we analyzed the input-output energy balance regard with movements of each part of the rider's body. As a result, it was clarified that lower body motions of a rider also have influences on the weave behavior of a vehicle.