Ms. Leslie P. Fowler Profile

Leslie P. Fowler

Senior Engineer

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Publications (5)

Proceedings Article | 10 May 2007 Paper

Adaptive filtering and feed-forward control for suppression of vibration and jitter

Eric Anderson, Ross Blankinship, Leslie Fowler, Roger Glaese, Paul Janzen

Proceedings Volume 6569, 65690Q (2007) https://doi.org/10.1117/12.718890

KEYWORDS: Control systems, Sensors, Digital filtering, Cryocoolers, Actuators, Filtering (signal processing), Mirrors, Acoustics, Servomechanisms, Digital signal processing

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Proceedings Article | 10 May 2007 Paper

Real-time optimal sensing strategies for active control of optical systems

Suk-Min Moon, Leslie Fowler, Robert Clark, Eric Anderson

Proceedings Volume 6569, 65690R (2007) https://doi.org/10.1117/12.719372

KEYWORDS: Sensors, Adaptive control, Digital signal processing, Actuators, Control systems, Detection and tracking algorithms, Optical components, Mirrors, Signal attenuation, Sensing systems

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The pointing and imaging performance of precision optical systems is degraded by disturbances on the system that create optical jitter. These disturbances can be caused by structural motion of optical components due to vibration sources that (1) originate within the optical system, (2) originate external to the system and are transmitted through the structural path in the environment, and (3) are air-induced vibrations from acoustic noise. Beam control systems can suppress optical jitter, and active control techniques can be used to extend performance by incorporating information from accelerometers, microphones, and other auxiliary sensors. In some applications, offline fixed gain controllers can be used to minimize jitter. However there are many applications in which a real-time adaptive control approach would yield improved optical performance. Often we would like the capability to adapt in real-time to a system which is time-varying or whose disturbances are non-stationary and hard to predict. In the presence of these harsh, ever-changing environments we would like to use every available tool to optimize performance. Improvements in control algorithms are important, but another potentially useful tool is a real-time adaptive control method employing optimal sensing strategies. In this approach, real-time updating of reference sensors is provided to minimize optical jitter. The technique selects an optimal subset of sensors to use as references from an array of possible sensor locations. The optimal, weighted reference sensor set is well correlated with the disturbance and when used with an adaptive control algorithm, results in improved line-of-sight jitter performance with less computational burden compared to a controller which uses multiple reference sensors. The proposed technique is applied to an experimental test bed in which multiple proof-mass actuators generate structural vibrations on a flexible plate. These vibrations are transmitted to an optical mirror mounted on the plate, resulting in optical jitter as measured by a position sensing detector. Accelerometers mounted on the plate are used to form the set of possible optimal reference sensors. Reduction of the structural vibration of optical components is attained using a fast steering mirror which results in a reduction of the corresponding jitter.

Proceedings Article | 19 May 2005 Paper

Optimal sensing strategy for adaptive control of optical systems

Suk-Min Moon, Leslie Fowler, Robert Clark

Proceedings Volume 5757, (2005) https://doi.org/10.1117/12.605544

KEYWORDS: Sensors, Actuators, Adaptive control, Optical components, Digital signal processing, Mirrors, Acoustics, Control systems, Detection and tracking algorithms, RGB color model

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Proceedings Article | 12 June 2000 Paper

Self-contained active damping system for pneumatic isolation tables

Leslie Fowler, Stephen Buchner, Vyacheslav Ryaboy

Proceedings Volume 3991, (2000) https://doi.org/10.1117/12.388168

KEYWORDS: Sensors, Actuators, Tolerancing, Optical isolators, Electronics, Motion measurement, Electromagnetism, Signal attenuation, Linear filtering, Calibration

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Proceedings Article | 5 May 1995 Paper

Individual feedforward-feedback control of a flexible rotor blade: a comparison of approaches

Leslie Fowler, Daniel Cole, Harry Robertshaw, Victor Giurgiutiu

Proceedings Volume 2442, (1995) https://doi.org/10.1117/12.208861

KEYWORDS: Feedback control, Control systems, Aerodynamics, Mechanical engineering, Performance modeling, Intelligence systems, Systems modeling, Mathematical modeling, Matrices, Defense and security

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