| Autonomous capsule robot can be safely and effectively used in noninvasive treatment for gastrointestinal diseases, which has become a milestone in the development of medical micro-robots. The wireless capsule robot with extracorporeal magnetic drive to achieve non-contact drive and active control, as well as the direction and attitude can be adjusted, has becoming a research project with important application prospect.Capsule robot has a unique petal-shaped profile, through in-depth analysis of the tiles surface fluid characteristics, achieve affected profile structure on driving performance. Under actual conditions, the instantaneous spatial location of capsule robot is unstable, so in the paper, eccentric motion characteristics of capsule robot is to expand research.First, a rigid petal-shaped capsule robot is presented, and multiple convergent wedge space have been formed between the convex profile of the petal and the pipe inner wall, resulting in the fluid motion path to change and thus generate multiple wedge effect. For providing main technical indicators for capsule robot, the viscoelasticity and biomechanical properties of gastrointestinal tissues are briefly introduced. An innovative technology solution is proposed, which employs three-axis orthogonal square Helmholtz coils fed with three phase sine currents to create a universal uniform magnetic spin vector to drive capsule robot moving in arbitrary direction.After that, the petal-shaped capsule robot with multiple wedge effects is analyzed in theoretical, taking single petal tile stretch surface of capsule robot as the research object, analyzing the characteristics of surface fluid velocity and clearance, and general pressure model is established. Using numerical integration method for solving steady swimming speed, while building radial equilibrium torque equation of capsule robot, and using software programming of matlab to solve structural parameters influence on the frictional resistance of liquid. The comparative analysis of driving performance between petal-shaped capsule robot and equivalent cylindrical robot is generated, with average fluid dynamic pressure of petal-shaped capsule robot and steady-state swimming velocity as single objective function respectively to optimize the profile design, selecting rational petal profile, giving full play to the role of multiple wedge effects, improving the non-contact drive performance. According to the fluid hydrodynamic properties of capsule robot with petal-shaped profile in the ideal conditions, established the mathematical model of oil film thickness of the capsule robot under the eccentric motion, and oil film stiffness coefficient and damping coefficient are used to judge the capsule robot swimming stability problem.Finally, in the pipeline filled with silicone oil environment, conducted the driving test of capsule robot under the level, tilt, spiral turning situations to verify the feasibility of control-driven by universal rotating magnetic field. Finally, in vitro pig and sheep intestines conducted straight line walking test to verify the robot’s movement through an unstructured environment to achieve good experiment effect test. |
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