Design of a reconfigurable automated landing system for VTOL unmanned air vehicles

Abstract

With the release of Bombardier's redesigned vertical take-off and landing unmanned air vehicle (VTOL UAV), the company's development team was interested in exploring fresh avenues for automatically landing the craft. The focus of this redesign revolved around navigation via DGPS data. The development of three principle components were identified as being paramount to the success of the system. First was the need for an algorithm to locate an appropriate intercept point on the intended landing profile. Landing initiated the switch of navigation modes from one using GPS to one employing DGPS. This differing of sources and their respective accuracies led to position errors between expected and actual craft location, thereby necessitating the inclusion of the flight-path intercept algorithm. With the establishment of concrete target points, a corroborative effort was required between the second and third components of the autoland system to provide motion control between two arbitrary points in space. The first of the two, a trajectory generator, provides an ideal locus of points based on a time law, paying careful attention to the craft's acceleration. A controller using the ideal points generated by the trajectory generator drives the craft and was the second component of the motion control system. The controller configuration was kept simple, due in no small part to the project's scope. The initial evaluation tool for theory development was a simplified version of Bombardier's overall craft dynamics model for the CL-327. This was then followed by tests with a high-fidelity model. Currently, flight testing is in progress.