Abstract
This paper investigates the problem of designing angle constraint guidance law against unknown maneuvering targets based on discrete-time sliding mode control theory. Invoking the fact that the future course of action of the target, an independent entity, cannot be predicted beforehand due to its complexity and unpredictability, a model-assisted discrete-time disturbance observer in cooperation with a singularity-free strategy is proposed first to estimate the target maneuver. Based on the reconstructed signal and a fast convergence time-varying sliding surface, a new chattering-mitigated super-twisting-like discrete-time impact angle constraint guidance law is then synthesized. Stability analysis shows that the closed-loop system trajectory can be forced to enter into a small region around the sliding surface. Simulations and comparisons with classical discrete-time sliding mode guidance law validate the effectiveness of the proposed guidance law.
Highlights
Proportional navigation guidance (PNG) law has been widely used in missile guidance system in the past few decades due to its easy implementation and might suffice for many typical cases of applications [1]
The simulation results, including interception trajectory, achieved acceleration, LOS angle profile, target maneuver projection estimation performance, impact angle profile as well as target maneuver estimation for Cases 1 and 2 are provided in Figures 3 and 4, where Figure 3 is for Case 1 and Figure 4 is for Case 2
One can note from these two figures that accurate interception is achieved under the proposed guidance law whatever the desired impact angle is, that is, the miss distances in these scenarios are less than 0:8m. These figures demonstrate that the LOS angles converge to their corresponding desired values during the homing engagement and proves that the proposed guidance law exhibits satisfactory performance in impact angle control with the small acceptable miss distance for different impact angles, that is, the impact angle errors in these scenarios are less than 0:5 deg. These results show that the proposed model-assisted discrete-time disturbance observer can accurately track the real target maneuver in noise-corrupted guidance environment
Summary
Proportional navigation guidance (PNG) law has been widely used in missile guidance system in the past few decades due to its easy implementation and might suffice for many typical cases of applications [1]. When applying continuous-time controller to discrete system, firstly, the system can hardly reach and maintain on the sliding surface due to the discrete form; secondly, the continuous stable system may be unstable, the stability theory of discrete system is different; the discrete system will result in time delay, chattering phenomenon, and invariable control command during sampling time [24] These are the reasons why designing guidance law in discrete-time manner is more desirable for practical interceptors. Motivated by the above analysis, this paper considers designing discrete-time SMC impact angle guidance law for unknown maneuvering target interception. (3) Based on the reconstructed target maneuver information, a new chattering-mitigated super-twistinglike discrete-time guidance law is proposed for accurate impact angle control.
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