Influence of base support on large gimbal performance

Large gimbal systems often demand high accuracy pointing and smooth travel. Feedback control is employed to guarantee this performance in the face of wind, bearing and other disturbances. Both small and large gimbal performance is affected by many common factors. However, in smaller gimbal system, the foundation has little impact on the performance of the gimbal feedback control and can be neglected. For larger gimbal systems, this is not the case. Fortunately, the control system designer can use simplified analytical models to characterize foundation designs assess the impact on the system. This information can be coupled with modern control design techniques to improve the performance under less than ideal foundations. Analytical work is supplemented with test results from two large terrestrial gimbal telescopes with significantly different foundation designs.