Actively steering a wheeled tractor against potential rollover using a sliding-mode control algorithm: Scaled physical test

Abstract

Tractor rollover is a severe safety problem in crop production. Active steering (AS) is an effective active control technology that can be used to enhance the lateral stability of the tractor. The purpose of this study is to implement AS system that converts tractor roll and pitch motion to restore the tractor attitude in a potential rollover. Based on the Lagrange method, a nonlinear time-varying attitude dynamic model is established according to different rollover statuses. A sliding mode control (SMC) algorithm for the tractor is constructed based on variable structure theory. A lateral stability indicator depending on tractor dynamic attitude is further proposed. The effectiveness of this SMC-AS control strategy was validated in simulation and scale-model experiments under various test conditions. The results showed that by adopting SMC-AS control, the roll-stable time of tractor was reduced by 46.07%, which demonstrates that the proposed SMC-AS control strategy was robust and effective. The developed approach is expected to supply technical support to help drivers to prevent tractor rollover accidents. • A 7-DOFs nonlinear dynamic tractor model is established. • The sliding mode algorithm is applied to active steering control strategy. • Simulations and scale-model experiments are conducted for verification.