Abstract: A petal-shaped capsule robot is proposed. The convergent wedge-like gaps are formed between the surface of four eccentric tiles and the inner pipe wall, and multiple wedge effects happens to the fluid when it flows around the four convergent wedge-like gaps when the robot rotating. Fluid Reynolds differential control equation and fluid dynamic equilibrium of the robot satisfying the boundary conditions of the outer surface of the capsule robot with spiral blades are derived. For investigating fluid dynamic characteristics and swimming speed, regarding swimming speed as objective function, optimization of petal-shape is conducted using genetic algorithm. The results show that both fluid dynamic pressure and swimming speed are improved within a certain gap range, achieving good driving performance and safety in the intestinal tract. With favorable adaptability to the unstructured environment and high driving efficiency, the petal-shaped capsule robot has a good prospect of applications inside the intestinal tract for diagnose and drug delivery.

Key words: multiple wedge effects, optimal eccentricity of petal shape, petal-shaped capsule robot