Impact angle constrained guidance for nonstationary maneuvering and nonmaneuvering targets

Abstract

Guidance systems with terminal impact angle constraints play a pivotal role in modern missile technology and defence systems. This thesis delves into the intricate domain of impact angle constrained guidance, focusing on its application against nonstationary nonmaneuvering and maneuvering targets. The research builds upon a foundation of proportional navigation guidance (PNG) and its adaptability for achieving precise impact angles. Guidance laws incorporating terminal impact angle constraints have been extensively explored in prior research, with notable contributions spanning across several studies [1–7]. Proportional navigation guidance (PNG) has emerged as a prominent framework for devising impact angle constrained guidance strategies applicable to both stationary and moving targets. Lu et al. [8] introduced an adaptive guidance law that harnessed PNG for achieving hypervelocity impact angle constraints against stationary targets. This thesis builds upon the foundational work of Ratnoo and Ghose [9], who addressed the challenge of satisfying impact angle constraints by adjusting the navigation constant N within the PNG framework. Their innovative two-stage PNG law was designed for realizing a broad spectrum of impact angles in surface-to-surface engagements with stationary targets. Kim et al. [3] further extended this concept with the introduction of a biased PNG (BPNG) law, which incorporated an additional term to nullify terminal impact angle errors while maintaining the conventional line-of-sight rate term for lateral acceleration commands. BPNG, in essence, expanded the capture region of existing guidance laws, particularly when dealing with moving targets, albeit with some limitations in tail-chase scenarios. One of the central challenges addressed in this thesis pertains to achieving impact angles against moving targets. Notably, the PNG law generates a set of impact angles for various values of the navigation constant N when targeting moving entities. However, classical PNG law studies [10] have revealed that N must exceed a minimum threshold to ensure bounded terminal lateral acceleration demand. To bridge the gap and achieve the full spectrum of impact angles, an orientation guidance scheme is introduced for the initial phase of the interceptor trajectory. This orientation guidance law, a derivative of the PNG framework, adjusts N as a function of the initial engagement geometry. Rigorous analysis and simulations demonstrate that following the orientation trajectory, the interceptor can seamlessly transition to N = 3, enabling precise control and attainment of any desired impact angle in a surface-to-surface engagement scenario. In conclusion, this thesis offers a comprehensive exploration of impact angle constrained guidance against a spectrum of targets, encompassing both stationary and moving entities. The research contributes novel insights into the application of PNG-based guidance laws, expands the achievable set of impact angles, and provides innovative solutions for addressing the complexities of nonstationary nonmaneuvering and maneuvering targets. The findings presented herein hold significant implications for enhancing the effectiveness of missile and interceptor systems in contemporary defence scenarios.