Modelling & Simulation of Dual Motor Drive Control for 11-meter Parabolic Antenna

Abstract

The 11-meter Parabolic Antenna control system at Master Control Facility (MCF) is utilized for spacecraft tracking throughout early launch phase and for 24x7 on orbit operations. The system has maximum driving velocity of 1 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sup> /s with maximum acceleration of 1 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sup> /s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .The control system is capable of keeping a tracking accuracy of 0.03 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sup> rss. The highly precise control requires a dual motor drive feed-back control in each axis, both azimuth and elevation to minimizes the back lash effect which is inherent to gear drive system. The dual motor system also eliminates the non-linearity from control system produced due to backlash effect.The precise control also requires proper tuning of the control system. The servo system here works on software based Proportional, Integral and Derivative (PID) algorithms. PID Controller are extensively utilized for spacecraft tracking. PID controllers are simple to implement but proper PID tuning is a tedious task. In this paper, the mathematical model of a complete dual motor drive Antenna control system is developed using System Identification tool of MATLAB. The model is developed with first order with zero order hold and convergence criteria are also ascertained.Different simulations are carried out in SIMULINK model and the behavior of dual drive system is studied with existing PID constants. Step response with various step sizes is simulated along with ramp response of the system. The results obtained from simulation are compared with the real system data and evaluated. Significance of this research work and future scope is concluded at last.