Local controllability of trident snake robot based on sub-Riemannian extremals

To solve trident snake robot local controllability by differential geometry tools, we construct a privileged system of coordinates with respect to the distribution given by Pffaf system based on local nonholonomic conditions and, furthermore, we construct a nilpotent approximation of the transformed distribution with respect to the given filtration. We compute normal extremals of sub-Riemanian structure, where the Hamiltonian point of view was used. We demonstrated that the extremals of sub-Riemannian structure based on this distribution play the similar role as classical periodic imputs in control theory with respect of our mechanism.