Reza Mohsenipour; Mehrzad Nasirian; Abdol Reza Kashaninia; Mohsen Fathi
Volume 8, Issue 1 , April 2015, , Pages 61-71
Abstract
Increasing in dimensions of the satellites and using light movingstructures, causes flexibility and uncertainty in their models. Therefor to control the attitude of the satellites, should use those methods which resist against the plant’s model uncertainty and could reject the disturbance and the ...
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Increasing in dimensions of the satellites and using light movingstructures, causes flexibility and uncertainty in their models. Therefor to control the attitude of the satellites, should use those methods which resist against the plant’s model uncertainty and could reject the disturbance and the measurementnoise. One of these methods is the robust control. But due to the location of the poles in the dynamic equations of the satellite, the design of robust controllers faces some problems. In this paper, using aninternal feedback, the dynamic equations are changed so that the poles are located in a more proper place. And then,considering flexibility affects as uncertainty and also, uncertainty in inertia matrix of the satellite, a H∞ controller, and finally to improve the performance, a µ-controller will be designed for the new equations. But these two controllers will be analyzed and compared for the primary equations and not for the new equations.For comparison, a classical controller is also designed forthe primary system.
M. Nasirian; R. Saleh; R. Shojaee
Volume 2, Issue 3 , December 2009, , Pages 51-56
Abstract
What is done in this paper is simulation of telemetry and telecommand communication between satellite and earth station as what exists in real earth station. Three software: Satellite predictive motion software, Monitoring and Control (M&C) software, processing Software are used in the simulation. ...
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What is done in this paper is simulation of telemetry and telecommand communication between satellite and earth station as what exists in real earth station. Three software: Satellite predictive motion software, Monitoring and Control (M&C) software, processing Software are used in the simulation. Satellite predictive motion software uses orbital equation extracted from Two Line Elements (TLE) to generate tracking elevation and azimuth angles of satellite. These angles as text file are input of M & C software. The M & C software has four modes as simulation mode, online mode, test mode and emergency mode. In simulation mode Acquisition Of satellite (AOS), Loss Of Satellite (LOS) and Pass Time (PT) are seen. The angles are produced and transferred to antenna servo system for moving antenna to desirable direction. Time of simulation is controllable and received signal level is displayed simultaneously. In this mode when satellite is observable, the telecommand can be send. In online mode all explained capabilities are valid except changing of time. In test mode antenna axis could move in desirable velocity and acceleration. In the other hand, when the satellite becomes lost, the system enters to emergency mode for searching of satellite. In the normal mode after receiving the telemetry data by M & C software this data as text file transferred to processing software. Processing software by protocol which accepted by satellite (HDLC based) recognizes the first and the end of telemetry frame and then extracts and displays the parameters. The telemetry parameters include online and offline data.
