Guidance and Control Design for the Ascent Phase of the Hopper RLV

Abstract

In this article the design of a guidance and control system for the automated ascent of the Hopper reusable launch vehicle is presented. The considered ascent starts at the pull-up maneuver performed immediately after horizontal take off and ends near main-engine-cutoff. The guidance (trajectory control) law is based on the coupled inversion of flight-path-toangle-of-attack and heading-to-bank-angle dynamics. The control (attitude) law uses also nonlinear dynamic inversion to obtain the required aerodynamic surfaces and engine gimbal deflections for robust tracking of the attitude angles from the guidance law. The used NDI attitude law is inherited from a previous design for the Hopper re-entry phase (with only minor modifications apart from the inclusion of thrust vector control) showcasing the reusability of NDI designs for quite different types of configurations. The resulting design has been validated using a Monte Carlo campaign with realistic aerodynamic mismatch, corrupted measurements, parametric uncertainty and high fidelity atmospheric and 6DoF vehicle dynamics models.