Metrology of the hexapod positioning systems for ground system equipment: recent innovations, and state of the art of reachable performances

This paper presents the performances of recent high-tech hexapod positioning systems. Those devices with six degrees of freedom, are commonly used in Ground System Equipment (GSE) design, to qualify and conduct, for example, optical performance test activities. They are frequently used in vacuum environments. This is the case for example for EUCLID, CHIME, PLATO missions. They are also commonly used on large scientific instruments like Telescope or synchrotrons.

The latest innovations in terms of the performances, measurement technology, stability and control of those positioners are presented. The know-how the manufacturer has mastered to mature this technology and push the boundaries is on display. The characterization of the performance in terms of resolution, repeatability, accuracy, cross-coupling, backlash, and stiffness is clarified. The methods and measurement instruments used to characterize each specification are explained. Then, the most advanced performances of different hexapod positioners are described in detail. The goal of this step is to provide the current state of the art of hexapod technology and describe the most advanced system. Ongoing innovations that could push the boundaries are also featured.

Finally, we present how engineers can specify their positioners to be integrated into the next generation of Ground Support Equipment (GSE). This analysis will include key parameters such as the stiffness, duty cycle, thermal management but also the control requirements.