The design was first conceived in late 2009.  Since then it has been refined through six iterations.  A production model of diameter 90mm could translate approximately 5mm in each direction and rotate 10 degrees around any axis that passes through the centre of the sphere.  

The mechanism contains three disconnected sets of mutually orthogonal motion decomposition assemblies each containing three gimbals.  The ends of the outer two gimbals form cylindrical joints over a set of 3D Cartesian axes which have a ball joint at the centre.  A sensor is mounted on the outer-most gimbal (the red part in the figure on the left below) and records movement across a tracking surface mounted on a paired gimbal (the blue part).  Each sensor measures translation and rotation along and around its corresponding axis.  

The large scale prototype was built over a period of a year finishing early 2011.  It can translate 30mm in each direction and rotate 9 degrees on any axis.  The prototype was drafted with Alibre Design.  

Nautamouse Prototype