Robust control strategy for generalized N-trailer vehicles based on a dual-stage disturbance observer

Articulated vehicles with multiple trailers also called N-Trailers have been widely used for transportation tasks in industrial applications. Solutions for the control problem of N-Trailers have been formulated mostly for vehicles with solely on-axle hitching or off-axle hitching but in field applications such as agriculture, most of the structures used are Generalized N-Trailers (GNT) which have a combination of on- and off-axle hitching. Moreover, most of the solutions in literature were developed and tested for laboratory-scale platforms under ideal indoor conditions. However, in outdoors conditions, the motion performance is commonly degraded by model uncertainties, slipping of wheels, and trailers localization loss product of noisy or inaccurate sensor data. In this context, this paper reports the use of Active Disturbance Rejection Control (ADRC) with a Dual-Stage Disturbance Observer (DS-DO) to improve the backward trajectory-tracking performance of GNT in no ideal conditions, where the DS-DO aims to attenuate the effects of error propagation on the ADRC compensation loop and improve the overall closed-loop performance. The proposed ADRC+DS-DO has been validated in simulation and real experiments showing overall improvements on the controller effort reduction and reduction of up to 57% on the tracking error against a traditional ADRC approach already existent in the literature.