The hexapod is a parallel kinematic manipulator that is the minimum arrangement for independent control of six
degrees of freedom. Advancing needs for hexapod performance, capacity and configurations have driven
development of highly capable new actuator designs. This paper describes new compact hexapod design proposals
for high load capacity, and corresponding hexapod actuator only mechanisms suitable for integration as structural motion
elements in next-generation telescope designs. These actuators provide up to 90 000N load capability while preserving
sub-micrometer positional capability and in-position stability. The design is optimized for low power dissipation and
incorporates novel encoders direct manufactured with the nut flange to achieve more than 100000 increments per
revolution. In the hexapod design we choose cardan joints for the actuator that have axis offsets to provide
optimized stiffness. The additional computational requirements for offset axes are readily solved by advanced
kinematic algorithms and modern hardware. The paper also describes the hexapod controller concept with
individual actuator designs, which allows the integration of hexapod actuators into the main telescope structure to
reduce mass and provide the telescope designer more design freedom in the incorporation of these types of motion
systems. An adaptive software package was developed including collision control feature for real-time safety during
hexapod movements.
This paper describes a high-force PZT-ceramic based linear actuator for long-travel, high resolution
applications. Different modes of operation offer high bandwidth dither, step and constant velocity slew motion.
The drive is self-locking and does not expend energy to hold a position. This development was originally
undertaken for applications in the semiconductor industry and mature serial production actuators are now
embedded in machinery to actively collimate heavy optic assemblies weighing 10's of kg in multiple axes with
nanometer resolution.
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