Robust maneuvering envelope estimation based on reachability analysis in an optimal control formulation
This paper discusses an algorithm for estimating the safe maneuvering envelope of damaged aircraft. The algorithm performs a robust reachability analysis through an optimal control formulation while making use of time scale separation and taking into account uncertainties in the aerodynamic derivatives. Starting with an optimal control formulation, the optimization problem can be rewritten as a Hamilton-Jacobi-Bellman equation. This equation can be solved by level set methods. This approach has been applied on an aircraft example involving structural airframe damage. Monte Carlo validation tests have confirmed that this approach is successful in estimating the safe maneuvering envelope for damaged aircraft.
Quantifying loss-of-control envelopes via robust tracking analysis
Nomenclature e control error r reference command x state vector S sensitivity function V airspeed [m/s] P set defining the permissible flight envelope R set of real numbers Sn set of symmetric matrices of size n T set admissible parameter trajectories α angle of attack [◦] ∆ uncertainty set ρ scheduling parameter
Tactical Flight Management Concept for Trajectory Based Operations
This paper introduces the concept of tactical flight management and outlines methods for implementation. In this context, the distinction between strategic and tactical is unrelated to the construction of a flight plan that is composed of a sequence of waypoints. Rather it distinguishes between approaches for generating and guiding aircraft along trajectories that connect these waypoints. This paper focuses on the descent phase of flight where the goal is to fly an idle thrust descent from cruise down to the runway. The conventional approach is to generate a strategic trajectory that optimizes performance while complying with constraints. Guidance is then provided to fly the aircraft along this static trajectory, deviating when necessary by transitioning between guidance modes. The proposed approach is to generate a guidance trajectory that is continually updated to achieve tactical objectives. This motion-based trajectory will represent an extension of the aircraft’s current state, and incorporate control laws and mode transition logic as part of the trajectory. This paradigm shift can provide a number of advantages when operating in the highly constrained and dynamic environment of the next generation air transportation system. These advantages include improved constraint compliance, reduced occurrences of mode confusion, and increased situational awareness of what the automation is doing now and what it is going to do in the future.