Abstract:Aiming at the problem of circular curve fitting, based on the parametric equation of circular curve, firstly this paper establishes the EIV model of circular curve fitting, and transforms the model into a more reasonable Partial EIV model for the characteristics of the coefficient matrix. Then, the formula is transformed into the least squares form, and the two-step iterative method is used to solve parameters of the model, ensuring that the corrections of the same elements in the coefficient matrix are same, and the corrections of the constant elements equals zero. Finally, combing case data shows the feasibility of this algorithm, and fitting accuracy is relatively superior.