Lin Defu

On Control for Static Unstable Missiles

Some benefit results on control for static unstable missiles are established. Based on LTI model of missile plant, it validates complete controllability and existence for pole assignment by output feedback instead of state feedback. The focus is to examine the control effect of two and three loop autopilot on a static unstable missile and determine the proper control strategy from a control capacity perspective. It will be shown that there are transformations that can provide equivalent closed loop properties for the output feedback opposite to state feedback in missile control field. The open loop properties will be some different, however. The analysis is accomplished by establishing a standard algorithm in virtue of MATLAB for autopilot design. The simulation results are indicated that this method has well practicability and robustness.

Missile two-loop acceleration autopilot design based on L 1 adaptive output feedback control

This article documents the design of a novel two-loop acceleration autopilot based on L1 adaptive output feedback control for tail-controlled missiles. The inner loop is an adaptive angle-of-attack tracking loop and the outer loop is the traditional PI controller for error compensation. A systematic low-pass filter design procedure is provided for minimum phase system and is applied to the inner loop design while the parameters of the outer loop are obtained from the multi-objective optimization problem. The effectiveness of the proposed autopilot is verified through numerical simulations under various conditions.

Terminal sliding mode based impact angle guidance law with observability enhancement

In this paper, a new impact angle constraint guidance law for stationary targets is presented based on terminal sliding mode control (TSMC) theory. The finite time stability of the line-of-sight (LOS) angular rate have finite time convergence under the proposed guidance law is obtained in theory. The boundness of unknown parameter estimation error is proven through Lyapunov method. Also, higher target observability is guaranteed by forcing an oscillatory missile motion trajectory. Numerical simulations results are provided to demonstrate the effectiveness of the proposed guidance law under different initial conditions.

Missile autopilot design using optimal control and frequency constraint

The benefits of relaxed static stability on missile were examined. Based on optimal control and open-loop crossover frequency constraint, an acceleration autopilot design methodology was developed and applied to a highly unstable airframe. Performance and robustness comparisons for three autopilot topologies were made. The analysis reveals the topology origin of classic three-loop autopilot, and simulation results show that the four-loop topology looks very promising.