Abstract:
In this paper, we discuss the LuGre model based parameter estimation of the
friction present in the 50/80 cm Schmidt telescope at the Aryabhatta Research Institute of
Observational sciencES (ARIES). Identification and compensation of friction in telescopes is
essential to achieve sub-arcsec pointing and tracking accuracies at very low velocities. The six
parameter LuGre model which is an extension of the Dahl model captures most of the observed
dynamic behavior of friction. High accuracy encoders mounted on the telescope axes are capable
of measuring micro and macro displacements useful for estimating the six parameters. A suitable
PI controller was developed for performing experiments on the Schmidt telescope to estimate
the friction. It was observed that the system exhibits the behaviour described by the LuGre
friction model.
