The Coordinated Control of Wheeled Mobile Robot on Loose Soil

Abstract

Generating the coordinated tractive force of each wheel for the robot is an important control objective in order to ensure the wheels to be the driven wheel but not the towed wheel. The tractive force is different between the front wheel and the following rear wheel because of the wheel's unequal sinkage caused by the compaction of loose soil. In this study, the mathematical model of sinkage is established to investigate the influence of repetitive passing on wheel sinkage, and the wheels' tractive performance is deduced on basis of the terramechanics. The equal drawbar pull generated by all the wheels under the optimal efficiency analysis is defined as the index to evaluate the wheel's motion consistency, as well as the coordinated control objective of wheeled mobile robot on loose soil. Furthermore, dynamic model of a six-wheel mobile robot is established and the fuzzy sliding mode controller is designed. Meanwhile, the validity of the proposed modeling and control method is demonstrated through the ADAMS co-simulation model. The result shows that control system has good performance in simulation.