Longitudinal Acceleration-based Variable Speed Bio-inspired Guidance Law

Abstract

Most analyses of existing interceptor guidance laws assume the interceptor speed to be constant, which simplifies mathematical analysis and enhances predictability in interception characteristics. In reality, this is not the case. This is especially true when drones are used as interceptors. Drones have the capability to vary their speeds over a fairly wide range of values. Therefore, traditional guidance algorithms for interceptors are not feasible when dealing with interception challenges.

This thesis presents an innovative guidance law known as the Longitudinal Acceleration-Based Variable Speed (LAVS) guidance law, drawing inspiration from the hunting strategies of Harris hawks. Observations from hawks’ behavior during prey attacks reveal their tendency to increase speed when the target does not maneuver (not stationary) and decrease it during target maneuvers. The LAVS guidance law integrates longitudinal acceleration commands with conventional pure proportional navigation (PPN) guidance law-based lateral acceleration commands, enabling the interceptor vehicle to engage targets that exhibit both maneuvering and non-maneuvering phases effectively. This approach significantly reduces the control effort required when compared to conventional guidance methods.

In the second part of this thesis, we conduct a qualitative analysis of the Variable Speed Pure Proportional Navigation (VS-PPN) guidance law. While researchers have previously tackled the capturability analysis of the constant speed PPN guidance law, the engagement equations involved prove highly nonlinear and challenging to solve, often yielding complex functions. Existing literature often relies on qualitative analysis techniques to determine capture conditions for constant-speed PPN guidance laws without solving motion equations. This thesis addresses the analysis of varying velocity, proposing a qualitative approach to establish capture conditions for a variable speed interceptor utilizing PPN for lateral acceleration commands. Additionally, this work explores Variable Speed Pure Pursuit (VS-PP) and Variable Speed Deviated Pure Pursuit (VS-DPP) guidance laws to identify the characteristics of those guidance laws during variable speed conditions and to facilitate a comprehensive performance comparison among VS-PP, VS-DPP, and VS-PN.

The third part of this thesis focuses on implementing the LAVS guidance law in a 6-Degrees of Freedom (6 DOF) drone model. The primary objective is to assess the practical effectiveness of the LAVS guidance law in real-time scenarios. This guidance approach combines longitudinal acceleration commands inspired by hawk attack strategies with lateral acceleration commands based on the conventional proportional navigation (PN) guidance law. It is employed when engaging targets exhibiting a combination of maneuvering and non-maneuvering phases. Furthermore, this research compares the LAVS guidance law with the conventional PN guidance law across various performance metrics, including control effort, time required for interception, energy consumption, and miss distance. The objective is to comprehensively evaluate the LAVS guidance law's performance relative to the PN guidance law across these critical parameters.