Development of the miniature video docking sensor

Abstract

To perform realistic demonstrations of autonomous docking maneuvers using micro-satellites, the MIT Space Systems Laboratory (SSL) developed a miniature universal docking port along with an optical sensing system for relative state estimation. The docking port has an androgynous design and is universal since any two identical ports can be connected together. After a rigid connection is made, it is capable of passing electrical loads between the connected micro-satellites. The optical sensor uses a set of infrared LED's, a miniature CCD-based video camera, and an Extended Kalman Filter to determine the six relative degrees of freedom of the docking satellite. The SPHERES testbed, also developed by the MIT SSL, was used to demonstrate the integrated docking port and sensor system. This study focuses on the development of the optical docking sensor, and presents test results collected to date during fully autonomous docking experiments performed at the MIT SSL 2-D laboratory. Tests were performed to verify the validity of the docking sensor by taking measurements at known distances. These results give an estimate of the sensor accuracy, and are compared with a theoretical model to understand the sources of error in the state measurements.