Modelling and in-orbit calibration practice of a miniature 2-axis analogue sun sensor

The modelling relations and calibration techniques of the miniature analogue sun sensors, developed at Surrey Satellite Technology Limited (SSTL), are discussed in this paper. Two model equations, an algebraic model based on a multi-variable polynomial algebraic curve-fitting procedure and a physical model based on analytical geometry relations, were developed. Parameter sensitivity analyses were conducted for the physical model, and an in-orbit calibration approach is proposed and was implemented with the sun sensors on-board UoSAT-12 and Tsinghua-1. A sequential batch filter algorithm was developed, based on the principle of the least-square estimation for regression models, to handle the large amount of in-orbit data in a sequential way. Satisfactory performance improvements have been achieved through the in-orbit calibration analyses for both satellites.