Jalil Beyramzad - Ph.D student of mechanical engineering, Iran University of Science and Technology, Tehran;
Esmaeel Khanmirza - Associated professor of mechanical engineering,Iran University of Science and Technology, Tehran;
Kamran Daneshjou - Professor of mechanical engineering, Iran University of Science and Technology, Tehran;

This research provides a technique for rigid satellite outputfeedback control that takes into account dynamicuncertainties and external disturbances without angularvelocity measurement. A rigid satellite's dynamics are firstexpressed using the modified Rodrigues parameter (MRP),and then translated into Lagrangian form to produce thestate-space description of the dynamics. Angular velocitydata is not always available for practical use due to cost ortechnological constraints. As a result, angular velocity isthought to be unmeasurable. To avoid additionalmathematical computations and design of separateobservers to estimate uncertainties and system states, athird order sliding mode (TOSM) state observer wasemployed to estimate uncertainties and system statesconcurrently. The primary element of the proposedcontroller also includes the full order terminal sliding modeapproach, which ensures finite-time stability and eliminateschattering. The simulation results of the suggestedtechnique have been provided and compared with theresults of methods accessible in the literature,demonstrating the effectiveness of the method described inthis study and the improvement of the findings of earlierrelevant research.

spacecraft - attitude control - state observer -full order terminal sliding mode – output feedback