Reach On Swimming And Driving Characteristics Of Petal Shape Capsule Robot

The application of medical micro robot in medical area can reduce the damage to human intestine organization, shorten the recovery time, decrease the medical cost and release pain of patient, thus it has become a research hotspot in the world.In this paper, a new kind of capsule robot with petal shape structure is proposed, the wedge-like gap between each petals shape tile and the internal pipe wall generates multiple wedge effects, achieving improvement of swimming speed, and olive-like shape along axis direction make the capsule robot turn much flexibly by reducing resistance easily, besides, rigid structure of the new kind of capsule robot make its application more practical and reliable.According to the two-dimensional Reynolds equation and Navier-Stokes equation, the kinetic equation of the capsule robot is established, the general solution is derived employing the variational functional and rayleigh step bearing method, then the effects of the structure parameters characteristics to multiple wedge effects are analyzed, the greatest steady-state swimming speed of the capsule robot inside straight pipe is chosen as the object function, the structural parameters of the capsule robot are optimized by SQP method.For the drive of capsule robot in bending environment, this paper proposes a technical scheme that three axis orthogonal Helmholtz coils is employed to generate a spatial universal rotating uniform magnetic field based on the magnetic field superposition principle. The intensity, angular speed and normal of the rotating magnetic field can be adjusted through three phase sine currents applied to the three coils.Electromagnetic mathematical model of the Helmholtz coils is established for analyzing the uniformity of rotational magnetic field as well as the regulation between the corresponding rotational direction of the magnetic field and symbols of applied currents in a cycle. The backard and forward driving principle of capsule robot inside bending pipe is analyzed and different currents formula in eight spatial quadrants are derived, the rotating regulation of the magnetic field in eight quadrants are also simulated.To investigate direction characteristics of a universal rotating magnetic field, three axis Helmholtz coils magnetic system, power sources with three-phase variable frequency control and multiple wedge effect capsule robot prototype for bending environment have been designed, manufactured and tested. Simulations and experiments have demonstrated that three axis Helmholtz coils can generate a spatial universal rotating uniform magnetic field with adjustable magnetic field strength, rotational speed and direction of rotational axis driven by three harmonic currents, achieving the drive of capsule robot forward and backward in curved environment vertically. This technology has a promising application prospect in medical engineering.