Improved peg-in-hole (5-pin plug) task: Intended for charging electric vehicles by robot system automatically

This paper deals with establishing of the electrical connection between a plug and a receptacle by a robot manipulator for the purpose of charging electrical vehicles. In general, the task of the robot for automatic charging of vehicles consists of two phases. In the first phase, the robot system defines the position of the charging receptacle of the vehicle using vision or infrared system. After that in the next phase, it starts to interact with the environment by connecting the charger plug to the charging receptacle (socket) of the vehicle. However, this phase is not always performed successfully, especially when the socket has complicated shape or consists of multi cores with different sizes. In this paper we will use robot force control to build up the connection. Additionally, an algorithm will proposed which improves the peg-in-hole task by generating spiral motion. The proposed algorithm has shown promising results performed on 5-pin industrial charger plug which is very hard to peg in the socket, even for the human, because it is secure and weatherproof (the plug should cover the whole socket cavity), moreover it has multi cores (5 pins) and it is provided with multiple notches to avoid mismatching between similar pins. In addition to that, the proposed algorithm has assumed that a small vision error could be occurred during estimating the initial position of vehicle´s receptacle.