The Kinematics And Control Method Researches For The Propulsion System Of The Robotic Dolphin

Robotic dolphins are usually studied as a kind of joint-caudal robotic fish, and there are two difficult problems need to be solved, namely, how to get a practical kinematic model, and how to achieve a closed-loop control for robotic dolphin’s movement. Targeting at the average propulsive speed of the robotic dolphin, this paper studies in depth the movement rule of robotic dolphin from the angle of locomotion feature extraction, and obtains a kinematic nonlinear feature equation based on kinetic energy mapping principle(KEMP), whereby a series of methods for achieving average forward speed control are explored. The research takes the KEMP and kinematic nonlinear feature equation as main lines, and progressively carries out a series of original researches in three aspects of the kinematic modeling, the single robotic dolphin locomotion and the group locomotion. It develops a new approach for the average speed implementation research of robotic dolphin.Firstly, the used hydrodynamic analysis method can hardly obtain the practical kinematic equation, thus this paper employs the feature extraction method to put forward the KEMP by aiming at the no phase difference case, the kinetic energy mapping coefficient(KEMC) is defined, and obtains the nonlinear kinematic feature equation. And then, this paper expands the KEMP to the travelling wave mode, and proposes the frequency displacement method, as a result of it, the KEMC is successfully obtained for the travelling wave mode.Secondly, considering there exist defects on open loop method for propulsion control, this paper further studies the average speed control implementation method for no phase difference mode by adopting the kinematic nonlinear feature equation. This study designs the iterative learning identification and adaptive control policy. An online identification method is used to get the value of the KEMC, and the value is directly used to generate the new input oscillating angle velocity of joint, then the expected target average speed is realized by closed loop method for robotic dolphin.Thirdly, the biological dolphin commonly swims in the way of the travelling wave. This paper contrastively analyzes the numerical variation characteristic of KEMC between the no phase difference and the travelling wave mode, and defines the same frequency feature oscillating(SFFO) and the phase difference factor(PDF), thus completes the mode transformation of the kinematic nonlinear feature equation. But, as a result of transformation, the kinematic feature equation under the travelling wave mode is much nonlinear. Therefore, a data-clamping design method is used to restrict the system’s operation in the design of control system, and the average speed target is realized for the travelling wave mode.The fourth, inspired by the kinetic energy mapping feature and implementation research of average speed under the travelling wave mode, this paper further studies the wave velocity driving method for the travelling wave mode. The method studies the matching characteristic between the average speed and the wave velocity of dolphin’s rear body, and proposes the speed-wave velocity matching principle and defines the speed-wave velocity matching coefficient(SVMC) by fitting the tail’s expanded wave, as well as calculates the matching equation. And then, a self-tuning control system based on SVMC is designed by applying the interval linearization policy and realizes the target average speed of robotic dolphin under the travelling wave mode.The fifth, the KEMP and kinematic nonlinear feature equation is expanded to the group movement for solving the consistency issue of robotic dolphin’s group speed. The kinematic feature equation group is proposed for a group of robotic dolphins. The consistent arrival method based on the parallel identification and the speed synchronization method based on the KEMC adjusting protocol are respectively designed, and the course consistency and target consistency are realized for robotic dolphin’s group speed.Finally, the KEMP is expanded to the yaw locomotion, and the two-dimensional data driven method is studied. The feature circle and feature radius are proposed by studying the concentric movement. And then, the two-dimensioinal feature data is proposed to respectively carry out the linear speed and angular speed motion by deeply studying the changing rule of KEMC.