Minglu Chi, Rongsheng Liu, Cheng Chang, Yuanli Wang, Huadong Zheng, Xiaoyan Qian, Qinchao Ren, and Ruihua Ren
Capsule endoscope, bivariate control, magnetic moment, decouplingcoordinates transformation, error correction
To drive and steer a capsule endoscope in a flexible and quick way, a magnetic field superposition method is proposed based on dimen- sionality reduction and decoupling control principles with the swing (χ) and pitch (ξ) angles as the double control variables. The control variables are reduced by decoupling coordinate transformation, while the operation flexibility of the capsule endoscope is realized through magnetic field orientation control. Based on the basic magnetic coupling moment equation, the bivariate steering magnetic moment is derived, while the relationship between pitch, swing angle, and magnetic moment is analysed. To eliminate the magnetic field error induced by the electrical parameters of the Helmholtz coil, a corrected basic driving current equation and a corrected bivariate steering magnetic moment model are derived. To verify the actual effect, preliminary control function experiments of capsule endo- scope are performed in a transparent straight tube and an in vitro porcine large intestine. The results show the effectiveness of the proposed bivariate magnetic torque control and laying a foundation for convenient and fast human–computer interaction.
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