Video guidance sensor flight experiment results

Abstract

An active video sensor system for determining target range and attitude was flown on STS-87. The Video Guidance Sensor (VGS), developed at NASA's Marshall Space Flight Center, demonstrated its capability in space and collected performance data. The VGS was designed to provide near-range sensor data as part of an automatic rendezvous and docking system. The sensor determines the relative positions and attitudes between the active sensor and the passive target. The VGS uses laser diodes to illuminate retro-reflectors in the target, a solid-state camera to detect the return from the target, and a frame grabber and digital signal processor to convert the video information into the relative positions and attitudes. The system is designed to operate with the target within a relative azimuth of +/- 9.5 degrees and a relative elevation of +/- 7.5 degrees. The system will acquire and track the target within the defined field-of- view between 1.5 meters and 110 meters range, and the VGS is designed to acquire at relative attitudes of +/- 10 degrees in pitch and yaw and at any roll angle. The sensor outputs the data at 5 Hz, and the target and sensor software and hardware have been designed to permit two independent sensors to operate simultaneously. This allows for redundant sensors. The data from the flight experiment includes raw video data from the VGS camera, relative position and attitude measurements from the VGS, solar angle data, and Remote Manipulator System position data to correlate with the VGS data. The experiment was quite successful and returned significant verification of the sensor's capabilities. The experience gained from the design and flight of this experiment will lead to improved video sensors in the future.