Nonstop update of running robot controllers

This paper presents a controller design on a RTOS platform to update running controller programs repetitively with small time loss. Field applications are the target of our study. The proposed online update method uses thread swapping in order to replace binary code without any customized operating systems or languages. We introduce a novel layered design based on update frequency for controller modules to manage the dependency among them. We present implementation expertise in update timing for performance improvement and show that a system of subsumption architecture is convertible to online updateable one. The overhead time of the method was measured by using a mobile manipulator and the results show that update can be completed within one servo cycle time.