Flight Control, Guidance, and Navigation

An important aspect of proposed hypersonic vehicles compared to hypersonic ballistic reentry is controlled maneuverability. This is a particular challenge since the high velocity introduces an extreme sensitivity to changes in the flight condition. The flight control system must ensure that the vehicle is always stable, that the response to autopilot commands is satisfactory, and that external disturbances do not produce unacceptable vehicle motions. The requisite dynamical models are nonlinear, unstable and with non-minimum phase, falling into a class of systems that are notoriously difficult to handle with traditional controller designs, as well as having significant uncertainty from aerodynamic effects and vehicle changes during flight.

The solution is likely to involve an adaptive controller that makes use of dynamic flight models, real-time sensors, actuators, and artificial intelligence.  In extreme cases of sensor and actuator loss, the flight controller needs to be capable of performing trajectory re-planning to recover stable motion and to minimize the deviation from the desired flight conditions. This will also require dynamic real-time planning capability that includes path planning algorithms with the ability to balance multiple competing mission objectives and risks.  

These challenging issues are the interest of the Hypersonic Systems Initiative's Flight Control, Guidance, and Navigation Focus Group, which is made up of experts in dynamic systems and control, high-speed sensors, automated control, flight control and swarming, and guidance.