The response of the rider’s body to roll oscillations of two wheeled vehicles; experimental tests and biomechanical models

This paper deals with a research aimed to identify the biomechanical properties of the rider’s body from laboratory tests. Special test equipment has been developed; it is a motorcycle mock up driven by a hydraulic servo-actuator that generates oscillations in the range 0.5–10 Hz. When the rider rides the motorcycle mock up, a system of sensors measures the input motion and the response of the rider’s body. The response of the rider’s body is represented in the frequency domain by means of frequency response functions: the motion frequency response function describes the lean motion of the rider’s trunk, the torque frequency response function describes the torque applied by the rider on the handlebars. The measured frequency response functions are used for identifying the parameters of lumped mass biomechanical models, which are suited to integration with the multi-body model of the motorcycle. Many experimental results are presented and discussed. Various biomechanical models are evaluated in terms of capability of reproducing the measured frequency response function. A good fitting of the motion frequency response function is achieved by means of a three-degrees-of-freedom model of the rider’s trunk, whereas a good fitting of the torque frequency response function is achieved by means of a five-degrees-of-freedom model of trunk and arms.