Flight test instrumentation system for small UAS system identification

Common open-source flight controllers have the ability to log state data, but they often are unable to log at the rates required to obtain good identification of model characteristics. They are also often unable to log important flow parameters such as angle-of-attack and sideslip angle. This paper presents a custom flight test instrumentation system that is capable of providing accurate full-state and control surface deflection measurements for Small Unmanned Air Systems. The system consists of an embedded single-board computer integrated with a collection of sensors including commercial off-the-shelf air data and inertial navigation systems, in addition to direct measurement of control deflections. Developmental Flight Test Instrumentation data logging software runs onboard the computer. This software is released as open-source. Performance of the system is verified by flight test on a quarter scale Piper PA-18 Super Cub airframe. The Observer/Kalman Identification algorithm is used in post-processing to generate linear statespace models, which are then simulated with other input sets and compared to flight data. Results presented in the paper demonstrate that the integrated flight test instrumentation system is able to provide sufficiently accurate data at a high enough sample rate for the generation of quality linear state-space models.