Design and control of a semi-passive, heavy-duty paired mobile robot system with application to aircraft wing assembly

Abstract

We describe the development of a robotic system capable of performing a class of manufacturing operations. An example of such an operation is commonly found in aircraft assembly - this demonstrates the immediate applicability of this research. The system utilizes a unique concept - a pair of mobile robots acting on opposite sides of a thin wall. The robots interact with one another through the use of magnetic fields that penetrate this wall. The 'inner' robot is untethered and is controlled by the 'outer' robot. Despite the significant mass of the outer robot, it operates without the aid of physical external supports. Full modeling of the system is presented. We include calculations for forces and torques produced by sets of permanent magnets for any system state. Simplified, tractable versions of this model for the purpose of control are also described. The system is designed to execute closed loop fine position control and large scale locomotion. Experimental results from a functional prototype verify the effectiveness of the design as well as the robustness of a position controller. Numerical optimal control results have been developed for high speed point to point trajectory motion. This 'pair of robots' paradigm could be applicable to a variety of tasks. This work outlines analysis techniques that are useful for such a system at most scales.