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detrimental to aero fins. Line-of-sight angular velocities of the ISMCG are less than those of the APNG with the actual target's acceleration. From Figures 2(a), 3(a), 4(a), and 5(a), in case 1 and case 2, ISMCG's guidance commands are smoother than others, which are appropriate for continuous aero surfaces to track. From Figures 2(b), 3(b), 4(b), and 5(b), because the ISMCG uses an adaptive estimation to identify atq's upper boundary, line-of-sight angular velocities of the ISMCG are not as moderate as those of the SMCG; however, from Table 1, line-of-sight angular velocities in the endgame of the ISMCG are less than those of the SMCG and the OSMG in case 1 and case 2. From Figures 6 and 7, the guidance commands and line-of-sight angular velocities of OSMG, SMCG, and ISMCG have little differences and are superior to

From Figure 8, it illustrates the δatq identified by the ISMCG in three cases under two conditions. Compared with ∣atq∣, in the initial 2 s, δatq is larger since q\_ and bk are larger, and then, the tracking error decreases since the ISMCG restrains the line-of-sight angular velocity. Because δatq is not the estimation of atq, tracking phases are considered and tracking errors are not concerned. Tracking phases reflect that estimations lag behind the actual target maneuver; thereby, it decides whether the compensation bk is timely and can influence the guidance precision. With tracking phases under consideration, δatq mostly tracks ∣atq∣ with a tiny time delay. In fact, for the step maneuver target in case 3, from Figure 8(e, f), δatq tracks ∣atq∣ well. As

In this chapter, robust guidance schemes are presented, which require states such as initial relative speed, relative distance, and error boundaries of them besides line-of-sight angular velocity. Proposed schemes' performances are validated by simulating under uncertainties for different target's maneuver modes. Two guidance schemes hit and kill maneuverable targets with fairly limited maneuverability. By comparisons with the APNG and OSMG, the ISMCG is superior, and the OSMG and SMCG perform similarly, whereas the APNG's miss distances are greater. Moreover, guidance commands of the APNG and ISMCG are smoother than those of the OSMG and SMCG for complicated maneuver modes of the target. In conclusion, ISMCG's advantage is that the guidance scheme is not required to obtain the target acceleration under

The future work concentrates on adapting the interceptor's maximum maneuverability to be a constraint condition in the proposed guidance scheme. Anti-saturation design is studied to

This chapter is supported by National Key R&D Program of China under Grant Nos. 2017YFD0701000 and 2016YFD0200700, National Natural Science Foundation of China under

shown in Table 1, small tracking phases obtain small miss distances.

uncertain conditions for different target maneuvers.

address the control-saturation problem in Eq. (4) [18–20].

those of the APNG in case 3.

38 Adaptive Robust Control Systems

5. Conclusions

Acknowledgements

Jian Chen<sup>1</sup> , Yongjun Zheng<sup>1</sup> , Yuan Ren<sup>2</sup> \*, Yuan Tian<sup>3</sup> , Chen Bai4 , Zhang Ren<sup>5</sup> , Guangqi Wang<sup>1</sup> , Nannan Du<sup>1</sup> and Yu Tan<sup>1</sup>

