An evaluation of ATV handling is presented in which participants, recruited for the study, operated an ATV that
could be configured to have two different steady-state cornering characteristics as documented in circle-turn tests on
an asphalt surface. One configuration produced an approximately linear understeer response (labeled US) whereas
the other configuration transitioned from understeer to oversteer with increasing lateral acceleration or speed on the
circle (labeled US-OS). Ten riders operated the ATV in both configurations on a serpentine off-road riding track and
were asked to complete a questionnaire to gather subjective impressions regarding the vehicles’ handling response
and suitability of purpose. The ATV was also instrumented to record objective performance and rider input data.
2.1. Vehicle selection
The ATV used in the study was a mid-sized general purpose/utility model with a 420 cc engine (Figure 2). The
ATV came equipped with front and rear independent suspension, a selectable automatic or manual transmission and
two- and four-wheel-drive capability. An ATV with these general specifications was chosen because its size would
be suitable for all adults, the participants in the study would not need to change gears during their evaluations and
the suspension could be modified relatively easily to obtain the different steady-state cornering characteristics. The
ATV was instrumented to record yaw, pitch and roll angles and associated angular velocities, the three principal
linear accelerations, speed and GPS position. In addition, the operator’s control inputs, including handlebar angle,
throttle and brake application were also recorded.
2.2. Handling response
To create the two steady-state cornering responses used in the study, the front and rear suspensions were
modified with the installation of an additional front and rear sway bar which were independently connected or
disconnected. The ATV with the front sway bar attached (labeled US) yielded an approximately linear understeer
steering response. Disconnecting the front sway bar and adding an additional rear sway bar produced a steer wheel
angle versus lateral acceleration response that transitioned from initially understeer (positive slope) to oversteer
(negative slope) and was labeled US-OS (Figure 2).