Alien Registration- Rosata, Antonette (Rumford, Oxford County)

https://digitalmaine.com/alien_docs/12341/thumbnail.jp

Identification of a small-scale helicopter dynamic model

The aim of this thesis is to develop a model for flight simulation of a radio controlled aerobatic helicopter, available in the Industrial and Civil Department of the University of Pisa. The purpose of the project is to make the small scale helicopter capable to complete a planned mission in autonomous flight, with automatic take-off and landing and sense and avoid capabilities. In the first part of this work, a non-linear open-loop analytic model of the rotor-craft is developed, with the discussion of hypothesis and possible simplifications. The second part focuses on the identification of the helicopter model parameters, based on a trust region reflective algorithm, in order to evaluate the inertial, aerodynamic and elastic variables introduced in the foregoing section. The accuracy of the developed model is verified by the comparison between responses from the model and flight measurements. In the last part, a simplified model is evaluated in order to define the transfer functions needed for the synthesis of autopilot control laws

Ridge subduction at an erosive margin - the collision zone of the Nazca Ridge in southern Peru

The 1.5-km-high, obliquely subducting Nazca Ridge and its collision zone with the Peruvian margin have been imaged by wide-angle and reflection seismic profiles, swath bathymetry, and gravity surveying. These data reveal that the crust of the ridge at its northeastern tip is 17 km thick and exhibits seismic velocities and densities similar to layers 2 and 3 of typical oceanic crust. The lowermost layer contributes 10–12 km to the total crustal thickness of the ridge. The sedimentary cover is 300–400 m thick on most parts of the ridge but less than 100 m thick on seamounts and small volcanic ridges. At the collision zone of ridge and margin, the following observations indicate intense tectonic erosion related to the passage of the ridge. The thin sediment layer on the ridge is completely subducted. The lower continental slope is steep, dipping at ∼9°, and the continental wedge has a high taper of 18°. Tentative correlation of model layers with stratigraphy derived from Ocean Drilling Program Leg 112 cores suggests the presence of Eocene shelf deposits near the trench. Continental basement is located <15 km landward of the trench. Normal faults on the upper slope and shelf indicate extension. A comparison with the Peruvian and northern Chilean forearc systems, currently not affected by ridge subduction, suggests that the passage of the Nazca Ridge along the continental margin induces a temporarily limited phase of enhanced tectonic erosion superposed on a long-term erosive regime

Alien Registration- Rosata, Antonette (Rumford, Oxford County)

https://digitalmaine.com/alien_docs/12341/thumbnail.jp

Power absorption optimisation in electromechanical primary flight actuators via control laws design

This paper deals with the design of optimal control laws for an electromechanical actuator used for primary flight controls. The reference actuator, essentially composed of a brushless DC motor coupled with a low-pitch ball-screw, is controlled is by two nested loops, on motor current and output position respectively. A basic structure of the actuator regulators is preliminarily defined by using a detailed model of the actuator, and then verified through experiments. Starting from this basic design, an optimisation of the regulators is performed by applying the LQR technique. Once linearized the detailed model of the actuator, different versions of optimal control laws are obtained by varying the structure of the optimisation cost function. The actuator responses with “tracking-oriented” optimisations (more focused on the tracking error minimisation) and “power-oriented” optimisations (more driven towards the current absorption reduction) are finally compared, highlighting and discussing advantages and drawbacks of the two approache