Preliminary Study on a Three-coil Wireless Power Transfer System for Endoscope Micro-robot of Intestinal Diagnosis: Design, Optimization and Validation

A wireless power transfer (WPT) system based on inductive resonant coupling makes it possible for endoscope micro robot (EMR) to explore intestine noninvasively. However, due to the increased demand for energy in such micro robot system, such as autonomous movement and drug delivery, the small receiving coil (Φ 15 mm × 13 mm) embedded in limited space on micro robot could not supply enough power as expected. To improve the power supply issue, this article proposes a three-coil WPT system for EMRs system. Based on the reflected impedance theory, the receiving end of three-coil WPT system is analyzed. Then, according to maximum power transfer principle, parameters relative to performance of WPT system have been optimized through simulation. After that, some bench tests are constructed. A good match is found between analysis results and experimental data. By comparing the three-coil PTW and two-coil WPT systems, it has verified that the transmission efficiency can be increased significantly to 11.2% by optimized three-coil WPT system and the power dissipation of receiving end could be reduced greatly when the micro robot is under a high power consumption, which is more suitable for endoscope micro robot system with limited space.