Paper Title
Performance Analysis of PID Control based Landing Guidance Strategies for a Reusable Launch Vehicle

Abstract - Approach and Landing is the final phase of descent of a reusable launch vehicle through the earth’s atmosphere. Traditional guidance strategies during this phase make use of multiple segments to land the vehicle safely on the runway. Recently, approaches based on single flight phase have been proposed for landing. This paper aims at a comparative analysis of two and three segment landing guidance strategies with a single segment guidance approach making use of PID control for generating closed loop commands. Closed loop normal acceleration guidance command is designed using PID control scheme and off-nominal conditions with worst case scenarios are considered for performance comparison between the guidance schemes. Numerical results are presented and analyzed for simulations based on both low and high energy conditions. The results indicate that single segment scheme is capable of handling large initial condition errors more effectively by giving minimal errors at touchdown compared to other schemes. Keywords - Guidance Strategies, Approach and Landing, Reusable Launch Vehicle, Closed Loop Guidance, Two and Three Segment Guidance, Single Segment Guidance.