====== PI Hexapod ======

VATT (starting summer of 2017) Uses a PI hexapod to precisely position the secondary mirror. 






===== PI Coordinate System =====

A full description of the coordinate system can be found {{:vatt:c887t0007_hexapod_coordinate_systems_en.pdf |here}}. I will summarize below. 


=== Hierarchies ===


The PI coordinate systems for the hexapod are created in a hierarchy. Each higher level adding to the lower level. THe lower levels should be permanent when the mount and orientation has been properly characterized.

Each level also has different possible types which can be user defined or left as the PI default. You can read the details of those types in the coordinate system manual

the hierarcies are:
{lower} -> {higher}
Leveling -> Orientational -> Operating
== Leveling ==
Permanent corrections to the alignment of the hexapod

== Orientational ==
permanent Rotation of the XYZ axes if necessary

== Operating ==
Described in detail below with sub types.

=== Work-Tool Concepts ===

The center of rotation always lies at the origin of the tool
coordinate system.

== Work Coordinate System: ==
    X, Y and Z directions are always spatially fixed

== Tool Coordinate System: ==
    X, Y and Z directions are permanently connected to the moving
    platform of the hexapod ie it moves with the platform. 




=== Operating Coordinate System ===
    The operating coordinate system is the "highest level"
    meaning it inherits properties from the lower
    level coordinate systems ie Orientational and Leveling
    The operating coordinate system has two Types KSD and KSF

== KSD: ==
        The work and the Tool coordinate systems are aligned
        at ZERO position only

== KSF ==
        The Work and the tool coordinate systems are aligned
        at the current position of the platform. Work Coordinate
        system stays at that position for any future moves ie
        you can move the work coordinate system away from
        the zero point to the current position.