Proceedings of the first International Conference on Research, Development And Education On Unmanned Aerial Systems (RED-UAS11, Sevilla, SPAIN), Nov 30, 2011
Proceedings of the first International Conference on Research, Development And Education On Unman... more Proceedings of the first International Conference on Research, Development And Education On Unmanned Aerial Systems (RED-UAS11, Sevilla, SPAIN)
This paper presents a tutorial for applying Kane's method to derive a mechanical model of a small-size helicopter. Throughout this development main concepts underlying Kane's methodology are explained in detail. Furthermore, references to other approaches in the field of classical mechanics are included to analyze the advantages provided by Kane's method when compared to other alternatives. Since this work considers the most general case of two rigid bodies, fuselage and main rotor, the resulting model will account for most significant modelling issues in the mechanics behaviour of a small-size helicopter, such as gyroscopic effects. Finally it is emphasized that the adopted pedagogical approach should contribute to illustrate the method to beginners
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Papers by Luis A Sandino
This paper presents a tutorial for applying Kane's method to derive a mechanical model of a small-size helicopter. Throughout this development main concepts underlying Kane's methodology are explained in detail. Furthermore, references to other approaches in the field of classical mechanics are included to analyze the advantages provided by Kane's method when compared to other alternatives. Since this work considers the most general case of two rigid bodies, fuselage and main rotor, the resulting model will account for most significant modelling issues in the mechanics behaviour of a small-size helicopter, such as gyroscopic effects. Finally it is emphasized that the adopted pedagogical approach should contribute to illustrate the method to beginners
Thesis by Luis A Sandino
In the framework of the EC-SAFEMOBIL project, this thesis proposes the use of a tether as a guiding element for safe landing of unmanned helicopters on moving platforms such as a ship deck. The possibility to include a Stewart platform in the tethered system in order to provide a horizontally stable landing surface by compensating ship's roll and pitch is also analyzed.
To this end, several mechanical models corresponding to each part of the tethered system (helicopter, tether, controlled winch for tether tension control and Stewart platform) are derived using Kane's methodology, which allows to obtain uncoupled first order differential equations. The resulting models offer a trade-off between simple and manageable equations for ease of the analysis for control design, and expressions that can accurately reproduce the main behavior of the real system. Upon analysis of the model, it is proved that the tether provides a stabilizing action against external disturbances, such as wind gusts, and also provides a new way to estimate the helicopter position relative to the platform, whose reliability would not be affected by the lack of GPS accuracy.
Taking into account previous conclusions on the system operation, control laws for each part of the tethered system are proposed. On the one hand, the application of linear control strategies for the helicopter (e.g. linear quadratic integral control, loop-shaping, gain scheduling, etc.) in the thesis scenario is addressed. On the other, an elaborate model-based non-linear control strategy is proposed. The design of these controllers depends on the relative position and attitude between the aircraft and the landing platform. Therefore, it is critical to develop algorithms to accurately estimate the system state with sensor data fusion. To that end, the use of a numerically efficient square-root Unscented Kalman filter is proposed to reliably close the control loop.
Finally, experimental simulations with the models used for control design as well as field experiments are presented for validation. These field experiments carried out by CATEC in the framework of the EC-SAFEMOBIL project, constitute the first worldwide experiments with a tethered unmanned helicopter.
This paper presents a tutorial for applying Kane's method to derive a mechanical model of a small-size helicopter. Throughout this development main concepts underlying Kane's methodology are explained in detail. Furthermore, references to other approaches in the field of classical mechanics are included to analyze the advantages provided by Kane's method when compared to other alternatives. Since this work considers the most general case of two rigid bodies, fuselage and main rotor, the resulting model will account for most significant modelling issues in the mechanics behaviour of a small-size helicopter, such as gyroscopic effects. Finally it is emphasized that the adopted pedagogical approach should contribute to illustrate the method to beginners
In the framework of the EC-SAFEMOBIL project, this thesis proposes the use of a tether as a guiding element for safe landing of unmanned helicopters on moving platforms such as a ship deck. The possibility to include a Stewart platform in the tethered system in order to provide a horizontally stable landing surface by compensating ship's roll and pitch is also analyzed.
To this end, several mechanical models corresponding to each part of the tethered system (helicopter, tether, controlled winch for tether tension control and Stewart platform) are derived using Kane's methodology, which allows to obtain uncoupled first order differential equations. The resulting models offer a trade-off between simple and manageable equations for ease of the analysis for control design, and expressions that can accurately reproduce the main behavior of the real system. Upon analysis of the model, it is proved that the tether provides a stabilizing action against external disturbances, such as wind gusts, and also provides a new way to estimate the helicopter position relative to the platform, whose reliability would not be affected by the lack of GPS accuracy.
Taking into account previous conclusions on the system operation, control laws for each part of the tethered system are proposed. On the one hand, the application of linear control strategies for the helicopter (e.g. linear quadratic integral control, loop-shaping, gain scheduling, etc.) in the thesis scenario is addressed. On the other, an elaborate model-based non-linear control strategy is proposed. The design of these controllers depends on the relative position and attitude between the aircraft and the landing platform. Therefore, it is critical to develop algorithms to accurately estimate the system state with sensor data fusion. To that end, the use of a numerically efficient square-root Unscented Kalman filter is proposed to reliably close the control loop.
Finally, experimental simulations with the models used for control design as well as field experiments are presented for validation. These field experiments carried out by CATEC in the framework of the EC-SAFEMOBIL project, constitute the first worldwide experiments with a tethered unmanned helicopter.