An Optimization Study for Occupant Comfort during a Three Wheeled Indian Auto-Rickshaw Ride for Low Frequency Vibrations

A three-wheeled auto-rickshaw (auto) remains one of the widely used modes of transport in parts of India. The vehicle structure places restriction in speed and it remains one of the ‘safe’ and cheap modes of urban commute medium in India. As part of data collection process, vibrations experienced in an auto-rickshaw ride were measured using 3 axis accelerometer fitted to the auto floor. A set of three maneuvers were planned in 4 different scenarios, namely, a stationary or idle mode, constant speed cruising(operating in speeds of 30,40 and 50 km/hour), a typical acceleration from idle to 30 km/hour and a typical braking or deceleration from 30 to 0 km/hour. The signals recorded were of the stationary random nature. The presence of 0.5 Hz dominant frequency in vertical and lateral vibrations denotes a higher tendency for motion sickness if travelled for a long period of time in auto. For auto operation at 50 km/hour, other modes were found at 10 Hz and 25 Hz, which indicate that the auto occupant would have a high chance of experiencing discomfort due to near human body resonance frequencies. Using SIMULINK, a single degree of freedom model of the vehicle was constructed for vertical vibrations and suspension parameters optimized for optimal ride.