A root hinge drive assembly is preferred in place of the classical viscous damper in a large solar array system.It has advantages including better deployment control and higher reliability.But the traditional single degree of freedom model should be improved.A multiple degrees of freedom dynamics model is presented for the solar arrays deployment to guide the drive assembly design.The established model includes the functions of the torsion springs,the synchronization mechanism and the lock-up impact.A numerical computation method is proposed to solve the dynamics coupling problem.Then considering the drive torque requirement calculated by the proposed model,a root hinge drive assembly is developed based on the reliability engineering design methods,and dual actuators are used as a redundancy design.Pseudo-efficiency is introduced and the major factors influencing the（pseudo-）efficiency of the gear mechanism designed with high reduction ratio are studied for further test data analysis.A ground prototype deployment test is conducted to verify the capacity of the drive assembly.The test device consists of a large-area solar array system and a root hinge drive assembly.The RHDA development time is about 43 s.The theoretical drive torque is compared with the test values which are obtained according to the current data and the reduction efficiency analysis,and the results show that the presented model and the calibration methods are proper enough.
