  Calibration is crucial for hexapods with high-accuracy positioning
capability. Many of these calibration procedures require measurement of
hexapod's platform pose (position and orientation) at constant temperature.
Consequently, thermal deflection of the hexapod's platform during pose
measurements impacts the accuracy of calibrated parameters. This paper presents
a method to eliminate the impact of thermal deflection of hexapods on their
pose measurement. In this method, a reference pose is measured before each
measurement of any particular pose. The measurements of reference pose are used
to estimate thermal deflection of hexapod's legs. This is in turn used to
estimate and correct the resulting pose error at the particular pose to be
measured. The advantage of using the proposed method is demonstrated
experimentally by means of pose measurements of a high-precision hexapod using
a CMM.
