Calibration plays an increasingly important role in enhancing robots positing accuracy. The research gives an overview of the existing work on robot calibration and points out the utility of calibration in areas such as the production, implementation and operation of robots. Modeling, measuremet, identification and compensation issues in robot calibration are discussed.

With a tunable cw semiconductor laser oscillating in a single longitudinal mode, measurement of an absolute strain is demonstrated with a frequency modulated interferometric method. Its measured resolution is 1.6 Hz/με, range is more than 3.5×106 με and just limited by the coherent length of the laser.