Analysis of Handlebar Vibration Mechanisms and Perceptual Characteristics During Push-Walking of Electric Motorcycle

Electric motorcycles produce less vibration and noise than vehicles with internal combustion engines. However, the cogging torque of electric motors can cause vibrations, particularly at low speeds. When push-walking a motorcycle at very low speeds, this cogging torque produces handlebar vibrations, resulting in discomfort for the rider. Since motorcycles are typically turned off during push-walking, it is impossible to reduce these vibrations through motor control. Thus, reducing handlebar vibrations through motor cogging torque design is required. To simulate vibration, a detailed and large-scale model that considers the characteristics of drivetrain components like belts and gears, is required. Consequently, the optimization of vibrations in the early stages of design is challenging. The ultimate goal of this study is to construct a simulation model that can predict handlebar vibration during push-walking. This report investigates the vibration transmission mechanism. Vehicle testing confirmed that vibration from the motor is transmitted to the handle through two distinct paths: one via the frame and the other via the belt drive. The excitation force is believed to come from the motor’s cogging torque. Handlebar vibrations caused by cogging torque during push-walking were confirmed to occur even in the stand-up condition. Handle vibration was found to be caused by vehicle resonance. Furthermore, by compensating for perceived vibrations in the hand and arm, it was inferred that vibrations below 100Hz are perceived directly through the handle during push-walking. Through an investigation of operational modes, vehicle modes corresponding to resonance frequencies were identified. However, a contradiction emerged during the discussion of the 30Hz mode. Therefore, the operational mode analysis must be reexamined, and further discussion is planned for future work. This study enables the definition of requirements for motors and vibration transmission components in the early stages of design, contributing to the development of electric motorcycles that reduce rider-perceived vibrations.