Robotics-Based Hardware-in-the-Loop Ground Test Facility for Dynamics and Control of Capturing Space Target

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The objective of this experimental program is to design and build a robotics-based hardware-in-the-loop (HIL) ground simulating facility to study full 6-DOF dynamics and control problems in the autonomous capture of free-floating targets by free-floating spacecraft-borne robotics. It will improve our understanding of soft-contact dynamics of two free-floating bodies in microgravity and control problems of post-capture attitude stabilization. The technology can be used for active debris removal and on-orbit serving of satellites. A thorough test and verification of the capture system and associated control laws on Earth before being launched to space is essential to mission success.******The proposed simulator consists of: (i) real-time computers that emulate dynamic responses of free-floating spacecraft-borne robotic manipulator and target based on multibody dynamics, (ii) robotic manipulators to physically deliver the computer-generated 6-DOF relative dynamic motion of the robotics and target, and (iii) mock up robotic gripper and target that contact physically to generate contact forces and torques. The hardware includes two high-bandwidth 6-DOF industrial robotic manipulators fully instrumented with force/torque sensors, one mechanical finger gripper as the end-effector, two workstations to perform real-time multibody dynamics simulation, and a camera for autonomous capture. The HIL simulator will allow us to accurately mimic the dynamic behavior of free-floating target and spacecraft-borne robotic manipulator in microgravity on Earth. This is achieved by the industrial robotics that strictly follows the 3D motion commands generated by real-time computer simulators, where the gravity effect is actively compensated. However, the contact dynamics between the gripper and target is real. Contact forces/torques will be measured and fed into the computer simulators to emulate the dynamic responses of the target and spacecraft-borne robotics in the next moment, subject to space environment and control input. This highly focused experimental program will open a new window to understand the soft-contact dynamics of free-floating spacecraft-borne robotics and target and associated control problem in multibody dynamics in microgravity. It will allow us to discover fundamental issues that may be overlooked by existing theories in normal conditions.******The simulator is essential for HQP to have a hands-on and space mission-like training environment. The proposed equipment will train 25 HQP. All HQP will be trained in multiple facets of technologies relating to multibody dynamics, control theory, mechanical design, machining and integration, electronic instrumentation, software programming, data acquisition and processing, design and implementation of a testing procedure evaluating the performance of the system, and development of operational procedures. These hands-on experiences and practical skills will make HQP more competitive in the job market.