Assessment of Model Predictive Control for Mars Entry Vehicles with Flaps

Flap-based steering systems on blunt-body Mars entry vehicles may improve flight performance relative to existing bank-angle steering systems. Successful implementation of aerodynamic flaps on a hypersonic entry vehicle requires an active control system to map angle of attack and sideslip angle commands to flap deflection commands. Here, a successive-linearization model predictive control algorithm and a linear-quadratic regulator are designed and assessed to address this multiple-input, multiple-output control problem. These two control algorithms are assessed in the presence of uncertainty in Monte Carlo simulations for various flap configurations and command profiles. While both control algorithms provide successful command tracking in the presence of uncertainty, the model predictive controller tracking errors are about half the value of those corresponding to the linear-quadratic regulator, indicating improved performance. Large uncertainties sometimes result in the linear-quadratic regulator failing to maintain control of the vehicle, while the model predictive controller remains successful. A comparison of several flap configurations shows the model predictive controller can be applied to various flap configurations successfully with only marginal performance differences between configurations, while the linear-quadratic regulator has a larger performance disparity between configurations and may require additional tuning to avoid controller failures when changing configurations.