Currently, a number of astrophysical institutes all over the world are working on the design of Extremely Large
Telescopes (ELT). Due to the enormous size of the primary mirror these telescopes make use of segmented mirrors.
These segments have to be positioned with respect to each other with nanometer accuracy in spite of all kind of external
disturbances such as wind loads, thermal loads, deformation of the base frame, varying orientation with respect to the
field of gravity, etc.
Janssen Precision Engineering (JPE) developed a revolutionary position actuator called the HiPAC which is able to
fulfill the demanding requirements for this kind of actuators.
The actuator is based on an integrated system of a pneumatic actuator, an electric voice coil and smart control strategy
and has the following features:
high positioning accuracy performance due to play-free and frictionless actuation;
high reliability and maintenance free operation due to flexure-based frictionless guiding;
system behavior is constant in time, because no parts affected by wear are used in the actuator;
low cost, because no highly accurate machined parts required to reach high end performance;
the position actuator acts as an integrated vibration isolator which isolates the segmented mirrors from
external vibrations induced in the telescope frame;
In this paper the design, simulation and measurements of the HiPAC actuator will be presented.