LATERAL TRAJECTORY STABILIZATION OF AGRICULTURAL TRACTORS ON SIDE SLOPES VIA CONTROL ALLOCATION ACTIVE SUSPENSION

Abstract

Operating agricultural tractors on side slopes causes dynamic weight transfer, asymmetrically degrading the tires' lateral grip according to the Pacejka characteristics. This disparity generates a Yaw moment, causing the vehicle to slip laterally, deviate from its trajectory, and face rollover risks. This article proposes a trajectory stabilization solution using an independent 4-cylinder active suspension system to automatically level the chassis. A 6-Degree-of-Freedom (6-DOF) full-vehicle mathematical model integrating hydraulic dynamics is established. To address the cross-coupling interactions among the suspension corners, a control allocation algorithm combined with PID loops is applied to accurately regulate four proportional valves. A digital twin is built on the Simcenter Amesim platform for validation. Under a 10 km/h scenario on a 20° slope, simulations show the system successfully maintains the chassis roll angle at approximately 0°, eliminating lateral weight transfer and restoring grip to all four tires. Consequently, lateral trajectory deviation is drastically reduced from 8 m to ±0.15 m, ensuring absolute directional stability for the tractor.