Wireless Power and Data Transfer for Robotic Joints Using High Coupling Magnetic Cores and Photodiode-Based Communication

Robotic systems, such as legged robots or industrial robots used in manufacturing and humanoid assistance, rely on robotic joints to perform multi-degree-of-freedom motions. Each joint typically incorporates a motor and a gear to drive its motion. Power delivery and control for these joints are usually achieved through cables for power and data transfer, which are routed through the joints. However, as the joints move, these cables bend and flex, leading to eventual failure due to the limited number of bending cycles they can withstand. In addition, in high-precision joints, cable slack can disrupt position control accuracy. To address these challenges, this article investigates wireless power and data transfer for robotic joints. The proposed approach leverages a closed magnetic core for power transfer, minimizing stray magnetic fields, and uses photodiode-based communication with a custom-developed control circuit. The approach is validated through experimental measurements and benchmarked against existing solutions in the literature. We demonstrate a system capable of transferring 200 W of power and achieving a data transfer rate of 2 Mbit/s, with the total weight of all components being 96 g.