Modelling and Control of an End-Over-End Walking Robot

Over the last few decades, Space robots have found their applications in various in-orbit operations. The Canadarm2 and the European Robotic Arm (ERA), onboard the International Space Station (ISS), are exceptional examples of supervised robotic manipulators (RMs) used for station assembly and mainte­nance. However, in the case of in-space assembly of structures, like Large-Aperture Space Telescope (LAT) with an aperture larger than the Hubble Space Telescope (HST) and James Webb Space Telescope (JWST), missions are still in their infancy; this is heavily attributed to the limitations of current state-of-the-art Robotics, Automation and Autonomous Systems (RAAS) for the extreme space environ­ment. To address this challenge, this paper introduces the modelling and control of a candidate robotic architecture, inspired by Canadarm2 and ERA, for in-situ assembly of LAT. The kinematic and dynamic models of a five degrees-of-freedom (DoF) End-Over-End Walking robot's (E-Walker's) first phase of motion is pre­sented. A closed-loop feedback system validates the system's accurate gait pat­tern. The simulation results presented show that a Proportional-Integral-Derivative (PID) controller is able to track the desired joint angles without exceeding the joint torque limits; this ensures precise motion along the desired trajectory for one full cycle comprising of Phase-1 and Phase-2 respectively. The gait pattern of the E-Walker for the next phases is also briefly discussed.