Experiments in robust path following control of a rolling and spinning robot on outdoor surfaces

This paper presents path following control experiments of a miniature spherical rolling and spinning robot mechanism on three different types of outdoor surfaces. The research is inspired from the efficient locomotory rolling patterns of various insects in unstructured environment. A nonlinear adaptive sliding mode (ASMC) feedback method maintains the robot stability and robustness in the presence of parameter uncertainties and external disturbances. The proposed path following control policy is developed, implemented and tested for the miniature spherical robot on three different types of irregular surfaces in outdoors. Path following accuracy, roll angle stability and wheel velocity response are three parameters measured to evaluate robot performance. ASMC controller capability is compared with an integral sliding mode (ISMC) controller. Experimental results show that proposed nonlinear robust control policy precisely tracks the different paths on these irregular surfaces in practical outdoor conditions.