| 1. |
- Pettersson, Anders, et al.
(författare)
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Nonlinear Feedforward and Reference Systems for Adaptive Flight Control
- 2013
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Ingår i: 2013 AIAA Guidance, Navigation, and Control Conference. - Reston, Virginia : American Institute of Aeronautics and Astronautics.
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Konferensbidrag (refereegranskat)abstract
- Use of feedforward can alleviate feedback and adaptive actions. Feedforward signals can be generated from reference models and the same models can also be used as reference models in adaptive control. A method for designing the reference models is presented in the paper. By exploiting the structure of the equations describing air vehicles it is possible to find reference models that scale to the present flight condition and vehicle configuration. Such reference systems are derived for flying vehicles in a generic manner, suitable for both winged aircraft and missiles. The same type of reference systems are also used to create trajectories for feedforward signals that compensate known plant non-linearities.
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| 2. |
- Pettersson, Anders, et al.
(författare)
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Analysis of Linear L1 Adaptive Control Architectures for Aerospace Applications
- 2012
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Ingår i: IEEE 51st Annual Conference on Decision and Control (CDC), 2012. - 0743-1546. - 9781467320658 ; , s. 1136-1141
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Konferensbidrag (refereegranskat)abstract
- In some situations the closed-loop system obtained by L1 adaptive control is equivalent to linear systems. The architectures of these systems are investigated and compared with internal model control and the input observer architecture. The analysis is focused on aerospace application. An effort has been made to understand and describe what fundamental control characteristic of flying applications that make L1 adaptive controllers suitable for the task.
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| 3. |
- Pettersson, Anders, et al.
(författare)
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Augmenting L1 Adaptive Control of Piecewise Constant Type to a Fighter Aircraft. Performance and Robustness Evaluation for Rapid Maneuvering
- 2012
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Ingår i: AIAA Guidance, Navigation, and Control Conference, 13 - 16 August 2012.
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Konferensbidrag (refereegranskat)abstract
- An L1 adaptive controller of piecewise constant type has been applied to a fighter aircraft by augmenting it to a linear state-feedback controller. Angle of attack and sideslip as well as velocity vector roll rate is demanded and controlled. It is relatively easy to design a controller augmentation this way; few parameters need to be tuned. To design an L1-controller for roll/pitch/yaw-motion of an aircraft, a five-state reference system with desired dynamics is created and three bandwidths of low-pass filters are chosen. The L1-controller activates when the aircraft aided by the feedback controller deviates from the reference dynamics. Load disturbance rejection is improved when the L1-controller is active. Results from simulations with different kinds of deviations from the nominal aircraft are presented. Special non-linear design elements need to be introduced if actuator dynamics, including rate limits, interfere with reference system dynamics. Since an L1 adaptive controller of piecewise constant type in its original form is linear time invariant, frequency domain analysis is presented, including comparisons to a typical linear state-feedback controller.
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