SPACECRAFT SIX DEGREE OF FREEDOM OUTPUT FEEDBACK CONTROL BASED ON DUAL QUATERNION

This paper investigates the observer-based output feedback control problem for the spacecraft in terms of dual quaternions. First, a coupled linear velocity and angular velocity observer, driven by the position and attitude (i.e., pose) measurements, is designed via the immersion and invariance (I&I) methodology. After dominating the cross terms in the pose dynamics induced by angular velocity by high-gain injection, the observer is shown to be exponentially convergent. An output-feedback pose tracking law is then derived by combining the proposed velocity observer and a full-state feedback proportional-derivative controller with proven separation principle. Finally, an asteroid hovering operation is simulated to demonstrate its effectiveness and application.