Design of real-time measurement system with Vision/IMU for close-range semi-physical rendezvous and docking simulation

Design of a real-time measurement system based on information fusion of Vision Measurement Unit (VMU) and Inertial Measurement Unit (IMU) is proposed for a semi-physical simulation system. Main contributions of the paper are the design and application of VMU-IMU integration to the real-time simulation of close-range rendezvous and docking (RVD) in lunar orbit. Structure and each component of the system are presented. The pose (position and attitude) filters utilized for information fusion within Kalman filter (KF) framework are designed, which regard Hill equations and quaternion differential equations as process models respectively and choose relative pose of two spacecraft as measure variables. Capabilities of the real-time measurement system are demonstrated by semi-physical closed-loop simulations, which show the proposed system yields more precise navigation result and more effective preservation of energy than an independent VMU.