Robust Funnel Synthesis Algorithms for the 6-DOF Powered Descent Guidance Control Problem

06/28/2024

As humankind enters a new era of space exploration, where the potential of reusable launch vehicles has been showcased by SpaceX and Blue Origin, the academic world has renewed its interest in autonomous landing algorithms. The terminal and most important phase of the landing sequence is commonly referred to as Powered Descent Guidance (PDG), where, using the available control mechanisms, the spacecraft needs to make final position and orientation corrections so it can land safely and smoothly. Throughout the literature published on this topic, convexification strategies have been proposed to compute, in an accurate and computationally efficient way, a reference landing trajectory. Furthermore, so-called funnel synthesis approaches have been applied to the PDG optimal control problem in order to provide additional robustness guarantees, by associating a control invariant set and a feedback controller to the reference trajectory and correcting deviations. However, such strategies fail to have an acceptable performance when unexpected additive random uncertainty and disturbance factors are considered in the dynamical model. For that reason, in this thesis project, two different approaches, both based on the funnel synthesis framework, are proposed to mitigate such issue. The first one is a Model Predictive Control (MPC) algorithm where the funnel parameters are leveraged to formulate a cost function and a terminal constraint. The advantage of including the funnel parameters in the optimization problem is shown, by comparing the corresponding performance with a standard MPC controller. The second approach is an algorithm that enables fast real-time reference trajectory and funnel recomputation.

Authors in the community:

• 

  G

  Guilherme João Verdasca Videira

  ist193262

Supervisors of this institution:

• 

  J

  João Miguel Da Costa Sousa

  ist12897

mechanical-engineering - Mechanical engineering

por - Portuguese

Instituto Superior Técnico