Control Algorithms for a Bidirectional Wireless Power Transmission System at the Redistribution of Energy Resources in a Group of Ground Robots

Abstract

Redistributing energy resources within a group of ground robots allows for an increase in the reachable workspace area and expands its functional capabilities. The use of wireless energy transfer systems for exchanging energy resources between ground robots reduces the requirements for positioning accuracy and enhances the reliability of the robotic system. This study examines control and management algorithms for a bidirectional wireless energy transfer system when operating as part of a ground robot. A structural diagram of the bidirectional wireless energy transfer module is proposed for integration into the robot’s control system, built on distributed principles. The developed algorithms take into account the specific features of the circuitry solutions of the bidirectional wireless energy transfer system, implemented using an uncontrolled resonant generator. The proposed solutions are tested on a robotics platform. The experiments focus on the process of replenishing the energy resources of one robot with another robot. Energy is transmitted between robots equipped with the same Li-ion battery, which has a nominal voltage of 7.4 V and a capacity of 5 A•h. The battery is charged from 50 % to 90 % capacity with different positioning accuracies of the robots. When there is a displacement of 4 mm and a distance of 4 mm between the receiving and transmitting coils, the charging time was 48 minutes, which is 5 % longer than the wired charging method. The maximum charging time reached 57 minutes with a distance of 15 mm between the robots. The use of bidirectional wireless power transfer for energy exchange between ground robots or for charging robots at a charging station enhances the autonomy of the group’s operation, as energy transfer can be successfully achieved even with low positioning accuracy. The proposed solutions can be used for battery charging and resource redistribution processes in groups of ground and underwater robots.