Multi-Sensor Measurement of the Motion Stability of an Active Controlled Isolation Test Pad

Performance data of a variety of motion sensors at controlled sub-seismic levels is presented. Sensors compared include representative state-of-the-art seismometers and tilt detectors, as well as newly developed quartz fibre linear and angular motion sensors developed under AGSC/FJSRL sponsorship, and the TGG gyro. The basis for a stable low level motion test pad, and calibrated, controlled excitations is a pneumatically supported, actively controlled Isolation Test Pad (Iso-pad). The Iso-pad is motion controlled at low frequency to local level with precision level-sensor/pneumatic-activator servos, and controlled at high frequencies in 6 degrees-of-freedom with inertial-sensor/electromagnetic shaker-activators. The current stability of the Iso-pad and its potential for ultra low noise instruments tests, is discussed as well as its use for controlled low level excitation of test instruments. (Author)