An Inertial and Aerodynamic Approach to Active Flutter Suppression Control Law Design and Wind Tunnel Evaluation
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Szymanski, Jacob
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Abstract
This thesis examines multiple continuous time adaptive control methodologies for use in Active Flutter Suppression (AFS). Typical AFS control methodologies rely on feedback in the form of inertial and elastic data such as acceleration and strain. This approach has been shown to be effective, however potential improvements may be made with the inclusion of additional information in the form of surface pressure data. Aeroelasticity involves the interaction of aerodynamic, inertial, and elastic forces, thus the inclusion of surface pressure data completes this triangle of forces.
There are two main parts of this thesis. The simulation portion examines the effectiveness of three adaptive control methodologies at mitigating flutter of a nonlinear aeroelastic simulation model. Due to the difficulty of simulating surface pressure fluctuations, the simulation models relied on the inertial data in the form of the pitch and plunge motions of the model for feedback. Analysis in both the time and frequency domains provided a complete
spectral analysis of the closed loop behavior of the model which provided insights into the underlying mechanisms acting within the adaptive controllers. Key pieces of information
were the energy transfer between modes of motion, frequency trends over time, and relative phase between deflections and control inputs. The most effective controller from the
simulations was selected for implementation on an experimental aeroelastic test rig in the
experimental portion of this thesis. The test rig was used to examine the effects of including the surface pressure data within a feedback control loop.
Experimental testing was conducted on a cantilever wing model which was instrumented with an angular rate sensor, an accelerometer, and upper and lower surface pressure transducers. Trailing edge flaps on the wing were used as the control effectors. The open loop behavior was characterized, then control with angular rate feedback into an adaptive
controller was evaluated. Multiple configurations of inertial and surface pressure feedback control were evaluated, with the final configuration achieving a 25% increase in flow velocity over the open loop case. Each control configuration was evaluated using spectral analysis to determine the modifications necessary to improve the control.
Overall, it was shown that the inclusion of surface pressure data provided information which was not present in the inertial data which enabled more stable control of the test rig. Controller tuning via examining the spectral information within the signals was found to be a valid approach which did not rely on precise modelling of the entire test rig.
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Date
2023-12-07
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