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Experimental study on the hydrodynamics of a pectoral-fin propulsive system

In nature a lot of fishes realize to suspend itself in water, to go forward and to move back up by the pectoral fin moving complexly. So that it is significant theoretically and valuable for practical application to investigate the propulsive principle and hydrodynamic performance of pectoral fin and find the method utilizing the pectoral fin to maneuver the underwater bio-robot agilely. The pectoral fin in propulsive system was composed of two servomotors to obtain various demanded feathering lead-lag coupling motions within the system limitation. The motion was sinusoidal in the experiment. The parameters included phase difference, oscillating frequency, oscillating amplitudes and angular bias. The hydrodynamic coefficients against time in a cycle were obtained and the experiment results were analyzed.