Laws For Stable Control Of Orientation

Class of globally stable laws for control of orientation of rigid body established. Tradeoffs made among complexity, performance, and information available for mathematical models. New approach involves use of globally nonsingular four-parameter unit-quaternion (Euler-parameter) representation. Attitude dynamics described by nonlinear Euler equation together with nonlinear kinematic equations, which relate representation of attitude to angular velocity of body. Suitable energy-motivated Lyapunov function to analyze stability.