Prediction of the lateral stability of a forestry chassis with an articulated body and fitted with luffing wheel-legs

Abstract

Due to the roads in forest being short of structured terrain, lateral stability of chassis is crucial for forestry vehicles. A forestry chassis with a novel articulated body and fitted luffing wheel-legs (AB + LWL) is proposed in this paper. The novel articulated body with three degrees of freedom which improves the ability to adapt to terrain is described. In particular, a luffing wheel-leg which enhances the lateral stability to run in forestry terrain, is proposed. After performing a detailed theoretical analysis of the mechanism equivalent, a new accurate the lateral stability model for the without driven luffing wheel-legs is derived. The new model predicts the lateral stability by analysis tyre contact forces, which is different from most models established by the geometrical position of centre of gravity. Significantly, a lateral stability model for an articulated body with driven luffing wheel-legs is derived. To verify the theoretical analysis, simulations that describe the lateral rollover for the chassis are established in ADAMS. The simulation is considered into two conditions, without driven luffing wheel-legs and with driven luffing wheel-legs. For the chassis without driven luffing wheel-legs, the lateral rollover is caused by the rear up-slope wheel when the inclination angle of slope reaches 34.8°. The maximum absolute percent difference of the rear up-slope wheel contact force with the theoretical analysis relative to the simulation is only 2.8%. For the chassis with driven wheel-legs, the lateral rollover which is also caused by the rear up-slope wheel will occur when the inclination angle of slope reaches 40.3°. The front or rear frame can be levelled by regulating the luffing wheel-legs when the inclination angle of slope is less than 15.29°. Compared with the chassis without driven luffing wheel-legs, the maximum inclination angle of slope increased 15.8%. The maximum absolute percent difference of the rear up-slope wheel contact force with the theoretical analysis relative to the simulation is only 1.6%. Simulation results validate the effectiveness of the proposed lateral stability models of the chassis in the two conditions. • Novel forestry chassis is proposed. • Lateral stability models not using geometric centre of gravity derived. • Simulations validated effectiveness of proposed lateral stability models. • New lateral stability models more accurate and more generic. • Articulated chassis with different active body control could be examined by models.