Investigation on Guidance and Control Schemes for Landing Phase of a Reusable Launch Vehicle

Abstract

The present research aims at an in-depth analysis of the existing guidance and control schemes and the limitations posed by these methods in effectively addressing the approach and landing problem. The focus is to develop novel guidance algorithms to achieve terminal constraints at runway touchdown and implement guidance and control methods for large trajectory deviations from nominal states as well as changes in aerodynamic parameters. newline newlineThe contributions of the present work are as follows: newline newlineA path planning algorithm is newly introduced during approach and landing making use of a single segment reference path connecting the approach and landing interface to the desired touchdown point on the runway. The concept is a novel attempt to use a single segment altitude profile for approach and landing based on a quintic polynomial that relates altitude with downrange. The main advantage is that a solution satisfying the initial as well as final boundary constraints on the vehicle states are attained with a lesser computational complexity. newline newlineA comparative analysis is carried out between three segment, proposed two segment and the proposed single segment guidance schemes using a common closed loop strategy. newline newlineThe touchdown position error is further reduced for the single segment scheme by implementing closed loop guidance using Fuzzy Logic Controller. newline newlineAn optimal strategy based on Model Predictive Static Programming is implemented to cater to the constraints on the control inputs along with the terminal constraints at touchdown. Large number of simulations are carried out under simultaneous varia- tions in initial states, vehicle and aerodynamic parameter variations to evaluate the performance of the scheme. This is also a novel attempt in the present work. newline newline