Energy Efficient Trajectory Tracking Controller for Underwater Applications: ARobust Approach

Unstructured oceanic environment and uncertain operating conditions of autonomous underwater vehicles (AUV) with limited on-board energy resources calls for the design of appropriate controllers to achieve optimal energy consumption while navigatingunderunstructured oceanic environment. With this aspect in mind, a sub-optimal robust control methodology has been presented here based on the appropriate switching surface design pertaining to the sliding mode control and an optimizer based on the solution of Euler-Lagrange equation for minimisation of total energy in relevance to the trajectory tracking of autonomous underwater robots within acceptable range of tracking error. The optimizer searches the local minimum in the nearest neighbourhood of the solution provided by the sliding mode controller and produces a sub-optimal solution.The system has been driven through composite 3-dimensional helical trajectories and reasonably accurate performance with substantial reduction of total control effort is noticed over the existing standalone controllers in spite of various parametric variations.