DKIST Enclosure Azimuth Mechanism adjustments for improved performance and reliability

The DKIST Enclosure Azimuth Mechanism is responsible for accurate positioning of the Enclosure in azimuth and provides a second degree of freedom to the altitude movement of the Enclosure Shutter which enables an overall position accuracy of 19 arcmin point-to-point at the Enclosure Aperture. The mechanism is primarily comprised of sixteen track rail segments, eight driven bogies, and two idler bogies, and it serves as the interface between the fixed support building Ring Girder structure and the rotating Enclosure structure. Visual observations and control system torque data have shown evidence of a loss of contact at the interface between the individual bogie wheels and the track rail sections. As a result, a project was initiated to improve the overall flatness of the azimuth track rails to improve performance of the Enclosure and reliability of the mechanism components.