| Popis: |
A two loop quaternion based state dependent Ricatti equation (QSDRE) control is proposed to improve the pointing performance of a large Earth Observation camera carried by a spacecraft. The system is modeled as two bodies, a spacecraft and a high resolution camera, connected by piezoelectric actuators to damp out vibrations, and a satellite mounted reaction wheel cluster to realize slew maneuvers. Disturbances coming from the unbalanced reaction wheels were also included in the model. The effectiveness of this two loop QSDRE control in improving the pointing performance demonstrated through simulations. Nomenclature A = cross sectional area of the Piezoelectric actuator D3 = vector of electrical displacement in polarized direction d33 = matrix of the piezoelectric effect in polarized direction E3 = vector of electric field in polarised direction Fa(t) = force exerted by the electric voltage Fp(t) = force applied in the piezoelectric actuator J = inertia matrix Ds, Dc = feedback damping matrices Ks, Kc, = feedback gain matrices l = length of the piezoelectric actuator n = number of piezoelectric stack P = stiffness matrix due to piezoelectric truss members S3 = vector of mechanical strains in polarized direction |
