This paper presents the single-axis angular motion equations of a large space structure assembled in orbit from separate elastic construction elements. We introduce a method to calculate the parameters of discretely varying dynamical properties of an assembled structure whose model has variable coefficients and inherent attributes of an elastic multi-frequency vibrating system. In addition, we suggest a parametrically tuneable algorithm for powered gyro control of such objects that guarantees desired dynamics at all steps of robotized assembly. Simulation results demonstrate the efficiency of the suggested algorithm.