Effect of speed bump on the ergonomics of a two-wheeler rider: Nonlinear model development, analysis, and experimental validation

Speed bumps are globally used to calm the traffic, thereby enhancing passenger and pedestrian safety. However, they significantly affect the rider ergonomics, especially for a two-wheeler. Thus, their design should incorporate passenger comfort as well. This research aims to investigate the biomechanical response of a two-wheeler rider traversing a rigid circular speed bump using a nonlinear spring-mass-damper model (SMD). The incorporates the contact between the tire and the speed bump (with potential detachment) and captures the vertical movement of the two-wheeler and the human body. Initially, the credibility of the kinematically simple SMD (for this analysis) is validated by comparing its results with those from a reliable and well-established multibody modelling technique. Additionally, several simplified SMDs are derived and compared. The article further documents the ergonomic effects (qualitatively and quantitatively) of speed bump dimensions and vehicular speeds along with physical interpretations. The results highlight the significant role of the bump dimensions and the vehicle speed in human discomfort. The study also investigates two simple novel vehicle design concepts for their effectiveness in improving rider ergonomics. The predictions from the developed model are compared with a few published works and are also validated against controlled experiments developed in-house. The findings offer significant insights into the influence of speed bumps on two-wheeler rider ergonomics, which can eventually lead to an ergonomically better design (of two-wheeler and speed bump).