COVER STORY FEATURE
THE MAN FROM HAWAII AND THE HEXAPOD
Astronomy has a strong tradition in Hawaii and precision technology is popular, because the precise alignment of telescopes is crucial. 6-axes positioning Hexapods, a technology well known to Physik Instrumente (PI), is sought after on the archipelago as the telescope reflectors require highly accurate positioning solutions to achieve their goals. However the PI design teams want to take the technology further
F
rankfurt Airport at 8:00am: The jet from San Francisco touches down in
the cold drizzling rain. The passenger on seat 5f has been travelling for many hours and started his long journey in Honolulu. He is not accustomed to the April weather and 120
C of the German
airfield and only brought with him some shorts and t-shirts. “We were quite relieved when the customer had to go shopping for long trousers and a sweater – this gave us two hours to perform some adaptations to the hexapod controller”, remembers Dr. Rainer Glöß from Physik Instrumente. That was in 1993 and the small team at PI had to make the best of those two hours writing tiny adjustments in the code for the complex controller of the hexapod. “For this project we not only had to develop the 3D transformations, the interfaces between the PC kernel and two digital processes from scratch, but also the command parser and all interfaces” explains Glöß. He used the time gained, thanks to the customer’s shopping tour, for final alignments to the Hexapod that our Hawaiian tourist had come to see. Later that day in the lab, interferometer
measurements gave the man from Hawaii an excellent understanding of the superiority of the Hexapod technology compared to conventional stacked architectures. The telescope market has been one of the key markets of Physik Instrumente ever since. More than 20 years later, the Hexapods
from PI are still sought after by science, research and the industry, because vertical integration, i.e. in-house programming of the controller, guarantees high quality and precise positioning which is crucial when searching for new galaxies and stars. Hexapods are sophisticated automation solutions and the controller has to coordinate six struts for an object to be moved in all degrees of freedom. The hardware is based on algorithms the end customer doesn’t want to know because
/ MICROMATTERS
they are so complex that only engineers with a mathematical background can understand them. The end result, is that the technology is extremely intuitive to use despite the complexities that went into its creation.
“The controller design has to be as
simple and as intuitive as possible, so that the Hexapod system can be easily integrated into the customer’s automation environment. Meanwhile, the
PRECISION AND ACCURACY Six degrees of freedom in motion, precision and accurate positioning of even high loads are the main advantages of the robot. So far, customers have mainly come from research and science, astronomy and wherever applications require high- precision positioning but the company wants to grow. The aim is Hexapods performing more and more positioning tasks in industrial manufacturing processes. For several years, the company has provided the six-legged robots to the automotive industry. Even the aviation industry with its huge wings can benefit from this technology, which is more than 50 years old. Further suitable applications have been identified in the machine tool sector. There are plenty of applications, but the industry is often in “wait and see” mode. Is the technology too complex? No it is not – the operating mode of a Hexapod is relatively simple and well understood; the crucial factors are easy control and integration of the product. This is what Glöß wants to convince his customers of and the PI Hexapod team is working on, programming and researching. Users can even use an app now to control their Hexapod, a scenario that the passenger on seat 5f could have only dreamt of. The connections to Hawaii have remained intact with the German technology still helping astronomers from Hawaii and Chile to control their telescopes – in spite of April weather.
Physik Instrumente
www.physikinstrumente.co.uk 01234 756 360
MICROMATTERS | SUMMER 2015 13 Figure 1 & 2:
6-axes positioning Hexapods, from Physik Instrumente located in the Chilean desert
solution also comprises simulation software enabling the customer to quickly calculate loads and workspaces. “Not even CAD software could offer such functionality this way.” Today, the system can be integrated via EtherCAT or other fieldbus interfaces.
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