Control methodologies for relative motion reproduction in a robotic hybrid test simulation of aerial refuelling

In many applications it is advantageous to simulate the relative motion of two bodies in a laboratory environment. This permits the testing of sensors and systems critical to the safety of equipment and personnel with reduced risk, and facilitates stage-gate management of large projects to mitigate financial risks. The University of Bristol is collaborating with Cobham Mission Equipment to develop a large-scale facility for relative motion simulation, primarily for the purpose of testing automated air-to-air refuelling systems. The facility incorporates two 6DOF articulated robotic arms whose motion is dictated by real-time numerical simulations of the physical environment. Sensors on the robot-mounted equipment feed back into the numerical simulation to perform closed loop simulations with real hardware. This paper discusses the development of the facility and the different approaches considered for achieving real-time control of the robotic hardware. It then goes on to focus on aspects of the control topologies and motion optimisation which are used to maximise the performance of the facility. The current capabilities are demonstrated with respect to an aerial refuelling exercise and future challenges are explored.