Session 2: Advances in Guidance Design 

Maximizing warhead effectiveness by ensuring impact at structurally vulnerable points is a key objective in missile guidance. This talk presents nonlinear guidance schemes designed to achieve precise target interception at a desired impact angle by establishing a unique relationship between the impact angle and the line-of-sight (LOS) angle. The approach is first developed for planar engagements across varying interceptor-to-target speed ratios and later extended to three-dimensional scenarios using a target-centric reference frame. Unlike conventional methods, the proposed strategies avoid decoupling and linearization of the nonlinear engagement dynamics, maintaining accuracy even under large heading errors. For high-speed targets, an impact-angle-based classification is introduced to distinguish between head-on and head-pursuit geometries, enabling consistent LOS angle assignment for a successful angle-constrained target interception. The guidance scheme comprises two phases: an orientation phase to adjust the interceptor's lead angle based on the desired geometry, and a LOS tracking phase that ensures finite-time convergence of LOS angle errors. The proposed methods are validated through simulations under diverse engagement conditions, demonstrating their robustness and effectiveness across time-varying interceptor speeds subject to aerodynamic constraints. 

This talk discusses a nature-inspired guidance and collision avoidance strategy, modeled on the attack behavior of hawks. Analysis on experimental data on hawk pursuit and obstacle avoidance reveals that a combination of lateral and longitudinal accelerations is essential for effective target interception and safe maneuvering around obstacles. To capture this behavior, we employed the Longitudinal Acceleration-Based Variable Speed (LAVS) guidance law. In this model, longitudinal acceleration is defined as a function of the distance to the nearest obstacle, serving as a collision avoidance term. This term activates when the interceptor enters a critical safety radius, prompting a rapid deceleration and enhancing its ability to maneuver. Simulation results validate the effectiveness of the proposed strategy in real-time scenarios, highlighting its potential for integration into advanced interceptor systems.

Proportional Navigation (PN) has long been a preferred choice in guidance systems due to its simplicity, effectiveness, and optimality. PN commands lateral acceleration proportional to the product of the navigation gain and the rate of change of the line-of-sight angle, thereby enabling effective target interception. However, in its classical form, it offers limited flexibility in enforcing terminal constraints, such as a specific impact angle. This talk presents a progression of ideas that enhance PN through variable gain strategies. We begin with a composite PN guidance law for stationary targets, where adaptively switching the navigation gain across different flight phases enables coverage of the full range of impact angles without lateral acceleration saturation. The second approach introduces a PN-based trajectory shaping law, in which the navigation gain is defined as a function of the line-of-sight angle, scaled by a single design constant—resulting in smooth, continuous lateral acceleration that ensures target capture with the desired impact angle. The third work presents a trajectory shaping guidance law that achieves desired impact angles while respecting seeker look-angle constraints through a closed-form variable gain, utilizing the line-of-sight angle and two design parameters. Collectively, these innovations extend the capabilities of PN, making it more versatile, constraint-aware, and applicable to modern autonomous systems.