Abstract: A dynamic model of a fishlike robot with undulatory motion based on Kane’s method is presented. Through kinematic description of the fish body with undulatory movement, the fishlike robot is divided into rigid head, flexible body and oscillating caudal fin which include many motion links. The dynamic model for a fishlike robot with multiple motion links is developed with the consideration of external environmental forces, such as the fluid added mass, the Froude-Kriloff force of fluid acceleration and the flow drag during fish swimming. The numerical example shows that acting moment of a motion link can be solved for given value of motion parameters with the exploitation of the dynamic model, and vice versa. Furthermore, the planning technique for the maximum thrust and highest propulsive efficiency can be explored by designing the motion law for each motion link. The dynamic model developed is a key theoretical support to the research on motion control algorithm as well as planning algorithm, and the revelation of dynamic mechanism of fish exploiting flow energy.

Key words: Dynamic model, Fishlike robot, Kane method, Motion link