A High Performance Petal-shaped Capsule Robot

Micro electromechanical system, sensor technology and image processing technology have made rapid development in recent years, and medical micro capsule robot has achieved a breakthrough on the basis of it. Active driving detection of capsule robot can effectively realize the human gastrointestinal tract with security and efficacy, will become a milepost in the medical field of gastrointestinal detection.To realize the active control of the capsule robot needs to solve two technical bottlenecks: the first technical bottleneck is to solve the problem of non-cable driven, magnetic drive provide a new way to solve the problem of energy supply and it has two ways:one is that the magnetic force is driven by an externally applied magnetic field of permanent magnets, and the second method is to spin the screw capsule robot which is driven by an external rotating magnetic field. The second technical bottleneck is the research of the principle of efficient driving in the gastrointestinal tract, realizing the driving of the capsule robot in complex environment. Breakthrough and put forward the space universal magnetic field drive technology and the spiral drive mode, effectively solve the above two technical bottlenecks. The theory established a foundation to capsule robot field. There are three main indexes to evaluate the performance of the robot,i.e. the average hydrodynamic pressure of the robot, the velocity of the steady state and the torsion moment of the liquid. Increasing fluid dynamic pressure can realize the whole suspension in the intestine, effectively improve the non contact swimming performance, avoiding the damage caused by contact with the robot, and increase the swimming speed can further improve the diagnostic efficiency. Reducing the torque of the liquid can weaken the robot's distortion of the intestinal tract, reducing the detection risk and improving the patient experience. The ideal robot profile should be improved by the three indexes.Firstly, inspired by the bionics and according to the related pressure phenomenon in the process of experiments, the petal-shaped capsule robot driven with excellent performance is proposed. The universal magnetic field space mechanism is introduced. According to the flow characteristics of the robot peripheral fluid, the Navier Stokes equation is simplified and velocity distribution is fulfilled. According to the step bearing pressure distribution rules, peripheral fluid dynamic pressure distribution of the robot is obtained, Newton inner friction law is employed to establish the axial and circumferential force equations of the robot.Secondly, from the theoretical level, the driving performance of different profiles is analyzed, and it is proved that the petal shaped capsule robot can not only improve the average hydrodynamic pressure and steady swimming speed, but also reduce the torque moment. Thus, the driving performance is improved comprehensively.Thirdly, the outer flow field of spiral drive capsule robot is investigated by the visual simulation software ANSYS FLUENT, founding the critical edge phenomenon, it describes the physical process of petal shaped capsule robot around the rotating flow. The critical edge phenomenon of the peripheral fluid surrounding the robot is discovered, i.e. fluid within the critical edge flows in the same direction as the robot swims, and the fluid out of the critical edge flows in the opposite direction as the robot does, while the fluid on the critical edge keeps stationary. Studies have shown that the fluid flow path is changed by the petal shape of robotic surface, meanwhile, hydrodynamic pressure and swimming speed increase as the edge of the area increases. Thus, the full suspension of the robot and non damage drive in intestine are realized.Finally, the experimental study of the four sets of robots prototypes are carried out, and it is found that the shape of the petal type capsule significantly reduces the torque of the intestine, and improves the pressure and velocity of the robot. The correctness of theoretical analysis is verified. Petal-shaped capsule robot with multi-wedge effects comprehensive performance improvement lay a solid foundation for the ultimate clinical application.