Autonomous Guidance of Agile Small-scale Rotorcraft

This report describes a guidance system for agile vehicles based on a hybrid closed-loop model of the vehicle dynamics. The hybrid model represents the vehicle dynamics through a combination of linear-time-invariant control modes and pre-programmed, finite-duration maneuvers. This particular hybrid structure can be realized through a control system that combines trim controllers and a maneuvering control logic. The former enable precise trajectory tracking, and the latter enables trajectories at the edge of the vehicle capabilities. The closed-loop model is much simpler than the full vehicle equations of motion, yet it can capture a broad range of dynamic behaviors. It also supports a consistent link between the physical layer and the decision-making layer. The trajectory generation was formulated as an optimization problem using mixed-integer-linear-programming. The optimization is solved in a receding horizon fashion. Several techniques to improve the computational tractability were investigate. Simulation experiments using NASA Ames 'R-50 model show that this approach fully exploits the vehicle's agility

System identification modeling of a model-scale helicopter

Abstract: Development of a reliable high-performance helicopter-based unmanned aerial vehicle (UAV) requires an accurate and practical model of the vehicle dynamics. This report describes the process and results of the dynamic modeling of a model-scale unmanned helicopter (Yamaha R-50 with 10 ft rotor diameter) using system identification. A complete dynamic model was derived for both hover and cruise flight conditions. In addition to standard helicopter flight characteristics, the model explicitly accounts for the stabilizer bar, which has a strong influence on the flight dynamics and is widely used in model-scale helicopters. The accuracy of the developed model is verified by the comparison between predicted and actual responses from the model and the flight experiments (in both frequency and time domains), and between key identified parameters and their theoretical values. Scaling of the main characteristics of the R-50 modelscale helicopter with respect to those of a UH-1H full-size helicopter was performed to determine how the size influences the flight dynamics of helicopters.

Diabetes care: opinions, needs and proposed solutions of Swiss patients and healthcare professionals: a qualitative study.

AIMS: To explore, both among patients with diabetes and healthcare professionals, opinions on current diabetes care and the development of the "Regional Diabetes Program". METHODS: We employed qualitative methods (focus groups - FG) and used purposive sampling strategy to recruit patients with diabetes and healthcare professionals. We conducted one diabetic and one professional FG in each of the four health regions of the canton of Vaud/Switzerland. The eight FGs were audio-taped and transcribed verbatim. Thematic analysis was then undertaken. RESULTS: Results showed variability in the perception of the quality of diabetes care, pointed to insufficient information regarding diabetes, and lack of collaboration. Participants also evoked patients' difficulties for self-management, as well as professionals' and patients' financial concerns. Proposed solutions included reinforcing existing structures, developing self-management education, and focusing on comprehensive and coordinated care, communication and teamwork. Patients and professionals were in favour of a "Regional Diabetes Program" tailored to the actors' needs, and viewed it as a means to reinforce existing care delivery. CONCLUSIONS: Patients and professionals pointed out similar problems and solutions but explored them differently. Combined with coming quantitative data, these results should help to further develop, adapt and implement the "Regional Diabetes Program"