Nonlinear dynamics and control of INSAT-II: application of a general formulation

Abstract

The paper presents a general Lagrangian formulation capable of studying the nonlinear dynamics and control of spacecraft with interconnected members in a tree-type topology. The nonlinear control, based on the feedback linearization technique (FLT) is adopted. The simplicity of the control algorithm and its applicability to both rigid and flexible spacecraft make the technique quite attractive. Application of the formulation is illustrated using a spacecraft of contemporary interest, INdian SATellite-II (INSAT-II), a next generation of multipurpose communications spacecraft launched in August 1992. The uncontrolled dynamics show the spacecraft to be in an inherently unstable equilibrium orientation. Control, based on the FLT, is then applied to restore the desired attitude of the spacecraft. The performance of three sets of control gains are compared. Even if the satellite is initially subjected to a large disturbance of 1° in pitch, roll, and yaw, the controller is successful in reducing the attitude err...