Design parameters study on the stability and perception of riding comfort of the electrical motorcycles under rider leaning

Abstract

Owing to noticeable differences of the characters between the electrical and the conventional gasoline-powered motorcycles, such as heavier in weight, lower in mass center position and slower in forward speed, the control and design considerations of the electrical motorcycles are not the same as conventional motorcycles. In this paper, the rider upper body lean control system is considered as the only control action to analyze and simulate the stability and the perception of riding comfort of the rider–motorcycle system in different riding conditions and parameter designs. The equations of lateral motion of an electrical motorcycle, which includes the rider upper body leaning motion, are derived first from Newton mechanics. Via this dynamics model and its associated transfer functions at various speeds, perception of riding comfort is defined as the damping ratio of frequency domain Bode plots in classical control theory. By the analysis, we find that the tendency of the stability is the same under the straight-line and the cornering motions, but shows significant differences for different parameter designs of the electrical motorcycle. We discuss the effect on the perception of riding comfort issue for changing mass center position, total weight of the motorcycle, the wheelbase, the front fork rake angle and the front wheel trail distance of the motorcycle. On the premise of the stability, we use the maximum damping ratio to represent the riding response of the motorcycle to find the best perception of riding comfort. By the analysis results, if we move the mass center forward, shorten the wheelbase, steepen the front fork rake angle and shorten the front wheel trail distance of the current design of electrical motorcycles in the market, a better perception of riding comfort is achieved. From the user's point of view, our analysis method of perception of riding comfort can be a supplement to the analysis of the stability of motorcycles.