Nonlinear attitude control of rigid body with bounded control input and velocity-free

In this paper a result on attitude tracking problem of mobile robot without velocity measurement and within the physical limits of actuator by the development of a novel Lyapunov function based on quaternion feedback is presented. The attitude of the rigid body is represented by unit quaternion, and introduces an auxiliary dynamical system whose output is used in the attitude tracking error. The analysis of the method shows that our control law guarantees almost global asymptotic stability in the case of bounded control input, and simulation results demonstrate that the controller can be used to perform large angle maneuver with short settling time and good steady-state performance torque.