Vector Field-based Guidance Development for Launch Vehicle Re-entry via Actuated Parafoil

Abstract

In this paper, a launch vehicles re-entry strategy using an actuated parafoil is analyzed. In recent years, this concept is gaining new momentum: it offers a lightweight and cost-effective control solution for autonomous landing of reusable rockets to specific ground or sea coordinates, as well as for mid-air capturing. This landing maneuver requires appropriate modeling together with suitable guidance and control strategies. This work expands upon the following aspects: (1) the development of suitable models for control synthesis and verification; (2) the design of heading control system; (3) the application of a path-following guidance law capable of steering the payload (i.e. the launch vehicle) to the prescribed end-of-mission point. Three models of increasing complexity are proposed based on different assumptions and the dynamics are compared in an ad-hoc simulation environment. MATLAB-Simulink is employed to design two versions of a 6 Degrees Of Freedom (DOF) model accounting for distinct aerodynamic effects. On the other hand, the multi-physics object-oriented language Modelica is used to develop a higher-fidelity 9DOF dynamic model of the system. The latter is then compiled and embedded within MATLAB-Simulink. The same environment allows the implementation of the designed Guidance and Control (G&C) algorithms. The G&C architecture comprises both low-level control loops, regulating course andyaw angles by means of differential steering commands onto the canopy strings, and a guidance layer where the VF path-following is employed. VF methods have already shown remarkable results for fixed-wing unmanned vehicles due to the lower steady-state errors as compared to other approaches, while retaining the potential for real-time implementation. With this work, the method is extended to the application of a launcher recovery. The results of the simulations are investigated, highlighting overall satisfactory performance even in presence of wind disturbances.