To keep the antenna performance at its optimum, the sub-reflectors even out external impacts on the mechanical system. Deviations can occur, for example, with antenna tracking that compensates for global rotation, with bending of telescope components due to gravitation, or through thermal effects or wind load.
The sub-reflectors are mounted on the hexapods which provide motion with 6 degrees of freedom. The PI Hexapod combines a load capacity of 200 kg with sub-micron linear resolution and microrad-level angular resolution. A digital motion controller provides advanced features, such as a user-programmable virtual pivot point, critical in complex alignment applications. Target positions in 6-space are commanded in Cartesian coordinates and reached by smooth vectorized motion. Hexapod parallel kinematics are lighter, more compact, and stiffer than conventional serially stacked multi-axis motion systems. The effect is a higher natural frequency with improved dynamics, faster step & settle, and higher stability.
High Altitude Controller – Fanless