Onground testing of satellite attitude determination and control system with three-axis motion simulator

In order to increase quality and reliability of newly developed satellite attitude determination and control systems (ADCS), on-ground testing is needed during their development as well as manufacturing. Moreover, the effectiveness of ADCS testing directly depends upon the accuracy of its operating environment simulation which requires highly accurate simulation of environmental effects on the sensitive items of the tested system. This article describes provision of accuracy when setting input effects on the ADCS sensitive items while performing dynamic bench tests using three-axis motion simulator which design is based on three-axis Cardan assembly. The article describes the calculation procedure and the algorithm of control input generation that affects the three-axis motion simulator while simulating absolute angular rate vector for the unit measurement channels, intended to measure satellite body angular rate. Motion simulator main advantages determined by its specific design are given. The article describes main kinematic relations and method of three-axis motion simulator calibration with reference to meridian that allows to take Earth angular rotation rate effect on the unit sensitive axes while the control input, affecting the simulator, is being generated, thus increasing the simulation accuracy. The research resolves an urgent issue which on the one hand allows to increase the quality of unit output performances measurement process, on the other hand it allows to increase effectiveness of ADCS on-ground testing. Effect of uncertainties of the three-axis motion simulator on ADCS dynamic performances measurement process in a damping mode was assessed using mathematical model method. The article also demonstrates that calculated kinematic relations and developed control algorithms simulate satellite angular motion accurately enough. Uncertainty of angular rotation rate in the set mode does not exceed 0.1 ′/sec.