Air Force Research Laboratory, Air Vehicles Directorate
Principal Investigator and Technical Lead
1 September 2015 – 31 December 2015
Total award $22,000
Because of the widely varying flight conditions in which hypersonic vehicles operate and certain aspects unique to hypersonic flight, the development of control architectures for these vehicles presents a challenge. One particular safety concern in hypersonic flight is inlet unstarts, which not only produce a significant decrease in the thrust but also can lead to loss of control and possibly the loss of the vehicle. Previous work on control design for hypersonic vehicles often has involved linearized or simplified nonlinear dynamical models of the aircraft, but a better approach is a nonlinear adaptive dynamic inversion control architecture with a control allocation scheme. This approach was shown to handle time delays, perturbations in stability derivatives, and reduced control surface effectiveness while maintaining tracking performance. The technical objective of this effort is to extend the previous work and develop state-constraint enforcement methods for an adaptive nonlinear dynamic inversion architecture. State constraint enforcement methods are necessary for all classes of aircraft, but are important for hypersonic aircraft. When the engine is operating in what is called “dual-mode,” the isolator is susceptible to over-pressure due to combustion, which can result in an inlet unstart. At other points in the flight envelope, an inlet unstart can occur when certain angle-of-attack or sideslip limits are violated. Initial work into enforcement of envelope constraints has successfully been done in the context of an adaptive dynamic inversion control law that assumes full-state feedback.
- Develop the formal theory for enforcement of both state and input constraints (position and rate limits) while maintaining stability.
- Address an extension of state-constraint enforcement in an output-feedback adaptive dynamic inversion architecture. In this case, the state that must be constrained may not be directly measurable and therefore have to be estimated.
Working with me on this program are Research Assistants:
- Douglas Famularo, Ph.D student
- Sean Whitney, B.S. student