Implementing caterpillar inspired roll control of a spherical robot

This paper presents a novel caterpillar inspired rolling gait generation and control mechanism of a spherical robot. The research investigates efficient locomotory rolling gaits of Pleurotya caterpillar in unstructured environment. A similar rhythmic rolling pattern is produced for the spherical robot locomotion. A synergetically combined feedforward - feedback control strategy is further proposed. The feedforward component is generated from centrally connected pattern generators (CPGs)in conjunction with nonlinear robot dynamics. A nonlinear integral sliding mode (ISMC) feedback method regulates these rhythmic patterns to adjust robot stability and robustness in the presence of parameter uncertainties and external disturbances. The proposed control strategy is developed, implemented and tested for the spherical robot on both smooth and irregular surfaces. The robot performance is quantified by measuring the stability in roll angle and wheel velocities. Experimental results show that proposed novel strategy is efficient in producing a stable rolling gait and robust control of a spherical robot on different types of surface conditions.