Abstract:The dynamic problem of an antenna pedestal is related to its tracking accuracy, and influences of external wind load on the antenna should not be neglected. Here, a 3-RSR (R represents revolute joint and S represents spherical one) parallel mechanism was taken as an antenna pedestal to analyze dynamic problem of a parallel antenna mechanism with a few-DOF. Firstly, the initial posture state of a parallel mechanism was described, and the posture matrix of each member of the parallel mechanism was obtained with the exponential product formula. Then, constraint relations between joints of motion pairs were used to deduce the constraint matrix of the parallel mechanism, and obtain Jacobian matrix and the velocity screw of each member. The acceleration screw of each member was obtained by deriving the differential form of the constraint matrix. Secondly, the inverse dynamic model of the parallel antenna mechanism was deduced according to the force balance relationship of each member. Considering the action of wind load, the dynamic calculation procedure of the parallel antenna mechanism was proposed. Finally, the software MATLAB and ADAMS were used to do numerical simulation for the dynamic model under motion states of pitch and azimuth, respectively, solve and verify this dynamic model. It was shown that the study results provide a certain guidance for improvement of dynamic performance and control realization of parallel antenna mechanisms.
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