On the control and stability of the pinhole occulter flexible boom facility

The dynamics and control of the Shuttle based, gimbal mounted, boom pointing system for use in the X-ray pinhole experiments were studied. The overall system stability was studied, and root locus compensation was designed to achieve stability and pointing stability requirements. This single axis control study found the compensated system to be stable and capable of pointing to within 6.5 arc sec while the Shuttle rocks in its 0.1 deg deadband. The system follows step (positon) inputs with zero error and rupm (velocity) inputs with a steady state error coefficient of 4.5/sec.