Practical Experence with Identification of Large Flexible Structures

This paper summarizes work done to experimentally characterize the combined actuator/structure/sensor system, and the control system hardware, of the ACES facility at the NASA Marshall Space Flight Center. The input-output frequency response functions of the actuator/structure/sensor system were measured for all analog actuator inputs and sensor outputs. System nonlinearity and time variance, measurements delays, and control hardware sampling delays and alias protection were investigated. Modal models of the system were generated from frequency response function data. State space models are formed from these modal parameters, for use in controller design.