Stable Wireless Power Transfer System for Capsule Robot Using Three-Dimensional Hybrid Transmitting Coil Pairs

Abstract

Wireless power transfer (WPT) in weak coupling has recently received widespread attention because it could be used to supply energy to capsule robots (CRs), allowing CRs (580 mW needed) to diagnose and treat diseases in the human body. In particular, exciting a three-dimensional (3-D) alternating magnetic field (AMF) for powering CRs has always been challenging since the randomly changing attitude and position can destabilize the induced power received by the coil on the CR. In this article, a novel WPT system based on three-dimensional hybrid transmitting coils (3DHTC) is proposed to generate stable energy for the CR. 3DHTC is a 3-D orthogonal coil system, consisting of a Helmholtz coil pair and two saddle-shaped coil pairs. The dimension of the 3DHTC is Φ70 × 35 mm. It can basically cover a 30 cm <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">×</i> 30 cm area of the human abdomen the design and implementation details of the new 3DHTC system are presented in this article. The 3DHTC system has been proven to excite a uniform and stable AMF covering the CR workspace by both analytical calculation and simulation analysis. Furthermore, a 1-D receiving coil (1DRC, Φ14 × 14 mm) is employed in the experiments to measure the AMF generated by the 3DHTC for its performance evaluation. The experiments illustrate the 3DHTC can supply stable energy of at least 777.63 mW to the 1DRC with randomly changing attitudes and positions, and the corresponding transfer efficiency ranges from 8.1% to 13.61%.