Hexapod 6-DOF Robots in Antenna Research and Alignment
Adjusting Commercial Satellite Dishes with Highest Precision in Multiple Degrees of Freedom
Hexapod 6-axis robotic positioners are versatile and high performance tools for antenna alignment applications. In the last century already, PI Hexapod Alignment Systems were used at ALCATEL SPACE, Cannes (France) for satellite antenna optimization at its Compact Range Facility. Here’s the story that was published in a PI newsletter back then:
A satellite antenna basically consists of a reflector and a feed. The reflector (dish) and the corresponding feed are built with respect to the specifications. Due to manufacturing tolerances the theoretical position of the feed does not completely fulfill the specifications. So relative movements of the feeds with respect to the reflector are necessary.
Alcatel Space has developed a new process for this optimization, called "Pathfinder System". After testing the feeds with their theoretical position, deviations are analyzed by software and hardware and the new optimized position for the feeds is determined. Pathfinder is fully automated. It controls two Physik Instrumente M-850 Hexapods to reach the optimized position of the feeds. The M-850 Hexapod is a complex six-degrees-of-freedom micropositioning system featuring better than 1 microns linear resolution and better than 5micro rad angular resolution in all axes. It also allows the user to define the pivot point anywhere inside or outside the system's envelope. Pathfinder drastically reduces testing time and increases performance, correcting deviations in pointing and gain with an accuracy of better than 0.01 mm and 0.001 deg. The new system has already demonstrated its full efficiency. More than 15 antennas have been optimized to date (1999).
In the years after this project, many more PI hexapods were used for similar antenna test and satellite antenna alignment applications. The most famous experiment where Hexapods were involved was the imaging of a black hole, with the Event Horizon Telescope, where the ATACAMA telescope array played a significant role. More than 50 of the telescopes are equipped with a PI hexapod to optimize the alignment of their secondary reflectors.
Improving mobile wireless networks may not be considered reaching for the stars, but it will make life on earth better for many people. The National Institute for Standards and Technology (NIST) has been working on higher performance antennas for next generation mobile communication and again, hexapod robots contribute to the solution.
The latest advances in alignment algorithms initially developed for hexapod-based high-seed silicon photonics circuits and fiber-optic component alignment can also be used for any type of multi-axis optimization from radio-frequency signals to optical lens alignment.
This is a legacy product that may have limited availability or may have been replaced. Ask a PI engineer for an equivalent new model.