Study of the effects of caster offset and kingpin offset on kinematics and lateral dynamics of long wheelbase solid axle bus

Wheel alignment parameters play a vital role in the handling behaviour of commercial vehicles. Thus, considering the future possibilities of active control of wheel alignment parameters, it is necessary to understand the effective range of use and limitations of the parameters mentioned on kinematics and dynamics of these vehicles. The objective of this work was to understand the effects of varying caster offset and kingpin offset on a long wheelbase bus and therefore an open loop study was conducted for the same. Handling response metrics were evaluated for three different manoeuvres, namely straight path driving, steady state circles and double lane change. The handling response metrics analysed include diameter of turn, tyre side-slip angles, body slip angle, yaw angle, yaw rate, chassis roll and forces at tyre road contact. A 2-variable (caster offset and kingpin offset) and 5-level design of experiments (DOE) was carried out using the full factorial matrix to determine the effects of the parameters on the above-mentioned handling metrics. The results show that both caster offset and kingpin offset have noteworthy influence on the kinematics and dynamics of the bus and hence their real-time control could be possibly considered for further improvement of handling performance.