Baldr Flight 6

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Baldr Flight 6

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Brian, Chris, Danny, Parul, and Raghu arrived at the UMore Park Airfield around 8:30am for the fourth, fifth, and sixth flights of Baldr. In addition to Baldr flights, there was one Fenrir flight that took place. A separate flight report describes the purpose of the Fenrir flight. Baldr is the UAV LabÕs newest UltraStick 120 airframe that will be used for aircraft reliability research. Baldr is a modified UltraStick 120 airframe that has split elevators and split rudders, each surface driven by a dedicated servo motor. Recently, efforts have been underway at the University of Minnesota to design fault tolerant control laws for UAVs. Specifically, researchers have been focusing on attempting to control Baldr using only the split elevators, with all other control surfaces locked into their respective trim positions. The key idea in this experiment is controlling a conventional aircraft with two coplanar control surfaces. There are two main motivations that drove this experiment: 1. Exploring the controllability of conventional aircraft (with an empennage) that have been severely handicapped with losses in multiple aerodynamic control channels, and 2. Drawing meaningful conclusions about the controllability of two-surface flying wing aircraft which are subject to faults in any one of the two aerodynamic control surfaces. For this experiment, the performance objectives were tracking phi and theta commands. Hence, only phi and theta tracking control loops were implemented. Researchers decided to modify the baseline loop-at-a-time controller for this experiment. The baseline controller has two independently designed tracking loops. The pitch tracking loop generates an elevator deflection command in order to track a theta reference. The roll tracking loop generates an aileron deflection command in order to track a phi reference. It is important to note that each of the split elevators induce both longitudinal and lateral-directional motions in the aircraft. When both elevators deflect symmetrically, they act as elevators. When both elevators deflect anti-symmetrically, they act as ailerons. Hence, the pitch and roll tracking loops can be retained, with the only addition being a control command reallocation block. The reallocation involves mapping the conventional elevator and aileron commands into left and right elevator commands. Finally, updated input trim settings for all the control surfaces (estimated from Baldr flights 1, 2, and 3) were used in this flight. This experiment used both elevators of Baldr to regulate outputs around trim and track phi and theta.

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Venkataraman, Raghu. (2015). Baldr Flight 6. Retrieved from the University Digital Conservancy,

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