An average propulsive speed control method for a robotic dolphin with wave velocity propulsion

By analysis of dolphin's propulsion characteristics, a speed-velocity matching method and an engineering speed-velocity matching equation (SVME) are proposed to describe the relation between the average propulsive speed and the body wave velocity. Furthermore, driving methods using the speed-velocity matching coefficient (SVMC) are put forward to realize the average speed control of the robotic dolphin. Firstly, the sinusoidal body wave created by the swimming dolphin is analyzed. The corresponding relation between the average propulsive speed and the wave velocity is determined, and the SVMC and the SVME are defined. Then, taking a three-joint caudal fin robotic dolphin as an example, a mathematical relation between the average propulsive speed and the dolphin's body wave velocity is determined based on the speed-velocity matching characteristics. Finally, according to the distribution of the SVMCs, an open-loop control method and a self-tuning control method are designed by using a partition linearization policy. The SVMC is taken as a feature data and used to drive the robotic dolphin's swimming, as well as to effectively realize the average speed control. The experimental results show a strict matching relation between the average propulsive speed and the dolphin's body wave velocity, and that the average speed control method using the SVMC is feasible.