New versions of Barbalat's lemma with applications

This note presents a set of new versions of Barbalat＇s lemma combining with positive （negative） definite functions.Based on these results,a set of new formulations of Lyapunov-like lemma are established.A simple example shows the usefulness of our results.

Stabilization of linear time-varying systems with state and input constraints using convex optimization

The stabilization problem of linear time-varying systems with both state and input constraints is considered. Sufficient conditions for the existence of the solution to this problem are derived and a gain-switched（gain-scheduled） state feedback control scheme is built to stabilize the constrained timevarying system. The design problem is transformed to a series of convex feasibility problems which can be solved efficiently. A design example is given to illustrate the effect of the proposed algorithm.

Wind disturbance compensated path-following control for fixed-wing UAVs in arbitrarily strong winds

Wind is the primary challenge for low-speed fixed-wing unmanned aerial vehicles to follow a predefined flight path.To cope with various wind conditions,this paper proposes a wind disturbance compensated path following control strategy where the wind disturbance estimate is incorporated with the nominal guiding vector field to provide the desired airspeed direction for the inner-loop.Since the control input vector for the outer-loop kinematic subsystem needs to satisfy a magnitude constraint,a scaling mechanism is introduced to tune the proportions of the compensation and nominal components.Moreover,an optimization problem is formulated to pursue a maximum wind compensation in strong winds,which can be solved analytically to yield two scaling factors.A cascaded inner-loop tracking controller is also designed to fulfill the outer-loop wind disturbance compensated guiding vector field.High-fidelity simulation results under sensor noises and realistic winds demonstrate that the proposed path following algorithm is less sensitive to sensor noises,achieves promising accuracy in normal winds,and mitigates the deviation from a desired path in wild winds.

Integrated guidance and control with input saturation and disturbance observer

In presence of input saturation,a novel integrated guidance and control(IGC)law based on the backstepping technique is proposed for missiles attacking manoeuvring target in this paper.A modified saturation function and an auxiliary system are proposed to deal with the input saturation.The state of the auxiliary system is used in the IGC law design process and stability analysis.Considering the uncertainties caused by target manoeuvres,model errors and variation of the aerodynamic parameters,disturbance observers which converge in finite time are introduced to estimate and compensate them.Based on the Lyapunov theory,the detailed stability analysis of the closedloop system is presented.The non-linear numerical simulations are presented to illustrate the effectiveness of the proposed IGC law.