Observer-Based Sliding-Mode Guidance Law

When taking the control loop dynamics of interception missiles into consideration,the designed sliding-mode guidance law often involves some feedback variables which are not directly measurable and some internal parameters that exists uncertainties.Based on adaptive control and estimation techniques,a novel observer-based adaptive sliding-mode guidance law was presented.The observer can realize the on-line estimation of the system states such as higher-order line-of-sight rate derivatives and the uncertainties such as higher-order closing-velocity derivatives for practical implementation.One-order maneuvering dynamics of interception missile was considered in the guidance law derivation and this approach can also easily be extended to the scenarios of high-order maneuvering dynamics.The nonlinear system simulations show that compared with the traditional proportional navigation and sliding-mode guidance law,this guidance law,with an enough maneuvering capability,can not only realize the hit-to-kill of the target,but also has advantages in maneuvering and homing performance.The simulation results also show the effectiveness of the designed observer.