Trajectory Optimization Procedures for Rotorcraft Vehicles, Their Software Implementation, and Applicability to Models of Increasing Complexity

This paper describes numerical procedures for the solution of trajectory optimization problems in rotorcraft flight mechanics. Specifically, procedures are considered that can be easily interfaced with black box flight simulators, with minimal assumptions on such third-party software components, and that can cater to a wide range of vehicle models of increasing complexity. First, the direct approach to the solution of maneuver optimal control problems is identified as the method of choice for this class of problems. Next, the direct transcription and the direct multiple shooting approaches are formulated, their characteristics are discussed, and their respective optimal application areas are identified. Finally, the functionality and architecture of a general-purpose code implementing both methods is described. The capabilities of the proposed procedures are demonstrated with the help of practical examples of industrial relevance, regarding both helicopters and tiltrotors.