Path tracking control of self-reconfigurable robot hTetro with four differential drive units

The research interest in robots with more than one steerable wheel has been increasing over recent years due to their high mobility while having a better payload capacity than systems using omnidirectional wheels. However, with more controllable degrees of freedom, almost all of the platforms include redundancy which leads to a modeling method based on the instantaneous center of rotation. The self-reconfigurable the robotic platform, hTetro, is designed for floor cleaning tasks. It also has four differential-drive units which can steer individually. Differing from most other steerable wheeled mobile robots, the wheel arrangement of this robot changes because of its reconfigurability. In this paper, we proposed a robust path tracking controller that can handle discontinuous trajectories and sudden orientation changes. Singularity problems are resolved on both the mechanical aspect and control aspect. The controller is tested experimentally with the self-reconfigurable robotic platform hTetro, and results are discussed.