Guidance laws with input saturation and nonlinear robust H∞ observers

- An ISS-based guidance law via a dead zone operator is proposed.
- The ISS stability of LOS rate is ensured though a term Hη is introduced.
- All trajectories starting in a reasonable region are restricted in the region.
- Sufficiently H∞ observers are proposed using Lyapunov theorem and convex optimization.
- A linear matrix inequality (LMI) optimization problem is constructed for H∞ observers.

A novel three-dimensional law based on input-to-state stability (ISS) and nonlinear robust H∞ filtering is proposed for interception of maneuvering targets in the presence of input saturation. A dead zone operator model is introduced to design an ISS-based guidance law to guarantee robust tracking of a maneuvering target. Input saturation and system stability are considered simultaneously, and the globally input-to-state stability have been ensured in theory. Since in practice line-of-sight (LOS) rate is difficult for a pursuer to measure accurately, the nonlinear robust H∞ filtering method is utilized to estimate it. The stability analyses and performed simulation results show that the presented approach is effective.