Optimal control of passive locking mechanism for battery exchange using Pontryagin's minium principle

Mobile robot market and its importance are rapidly increasing. Mobile robots usually mount batteries to extend operating time and workspace. For that, robot has to charge the battery while stopping at a station or exchange the battery. Charging battery is too slow to restart robots. Therefore, battery exchanging method is encouraged. Until now, this method needs expensive sensors such as laser range finder and vision sensors to align and is very complex mechanism which including battery removal from robot, moving to the station, docking mechanism and exchange mechanism. Thus, we proposed a new complete passive battery docking and exchange mechanism. This mechanism uses no actuators at whole actions. And it simplifies the process that unifies the docking and exchange mechanism using key and housing system. This system reduces the docking and exchange operating time and compensates wide range of offset between battery and charge station. But this mechanism needs optimal control of robot moving, because this system is composed of springs and dampers which are passive modules that should be controlled accurately. This paper proposes optimal control of robot moving at passive docking mechanism in battery system for reducing docking time, rebounding force and stable docking using Pontryagin's minimum principle. Also this paper verifies proposed optimal control using dynamic analysis program, Recurdyn and Matlab Simulink.