An Investigation of Operator Performance in All-terrain Vehicle (ATV) Handling and Control

Abstract

The handling properties of All-Terrain Vehicles (ATVs) have been the subject of numerous investigations over the last two decades. Because the great majority of ATVs use a solid rear axle or a direct drive to both rear axles for improved off-road traction, these vehicles typically transition from understeer to oversteer with increased cornering severity in tests customarily used in the automobile industry to measure steady-state vehicle handling properties. An oversteer handling response is contrary to the accepted norm for on-road passenger vehicle handling and, for this reason, has drawn scrutiny from the Consumer Product Safety Commission (CPSC) staff and others. In the research described in this paper, an evaluation of ATV handling is presented in which 10 participants operated an ATV that was configured to have two different steady-state cornering characteristics. One configuration produced an approximately linear understeer response (labeled US) and the other configuration transitioned from understeer to oversteer (labeled US-OS) with increasing lateral acceleration in constant-radius turn tests. Participants found that the ATV with either the US or US-OS steady-state handling characteristic would be satisfactory for their typical use of an ATV; however, participants overwhelmingly preferred the US-OS Configuration. No participant reported that either configuration was unpredictable, although the ATVs were rated as more comfortable and received better steering feedback ratings for tight turns when configured to and operated in the US-OS Configuration as compared to the US Configuration. The objective data did not indicate that there was a control issue associated with the ATV configured to have an understeer/oversteer steady-state handling response. Course excursions were observed with both configurations, with the most significant occurring with the US-configured ATV. In summary, passenger car control response characteristics that have traditionally been found to be conducive to vehicle safety and control in that environment cannot be directly applied to the understanding of ATV safety and control.