Highlights of CDCSS-UMD Accomplishments
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Transcript of Highlights of CDCSS-UMD Accomplishments
Harvard - Boston University - University of Maryland
Highlights of CDCSS-UMD Accomplishments
Presentation to Dr. Randy Zachery
Army Research Office
May 25, 2004 at Harvard University
Harvard - Boston University - University of Maryland
Accomplishments• Adaptive Optics
- Proof-of-concept experimental demonstration of the liquid crystal light valve (LCLV)-based high resolution wave-front control system (nonlinear Zernike filter realization)
- Simulation results show effectiveness against atmospheric turbulence
- Global nonlinear stability analysis for the continuous system model of the wave-front control system
- Patent disclosure (PS-2001-078) jointly to University of Maryland and Army Research Laboratory: Wave-front phase sensors based on optically or electrically controlled phase spatial light modulators for wave-front sensing and control (M.A. Vorontsov, E. W. Justh, L. Beresnev, P. S. Krishnaprasad, J. Ricklin)
Harvard - Boston University - University of Maryland
From nonlinear Zernike filters to high-resolution adaptive optics
Harvard - Boston University - University of Maryland
Accomplishments• Modeling, Computation and Control of Magnetostrictive Hysteresis
- Effective numerical computation of magnetostrictive hysteresis in materials such as Terfenol-D using the Landau-Lifshitz-Gilbert (LLG) equation to model ferromagneto-dynamics, and elastic rod theory to model actuator movement
- Hierarchical tree-structured Fast Multipole Algorithm to compute magnetostatic term in effective field, coupled to a new Cayley transform- based geometric integrator for solving the LLG equation, to compute theoretical hysteresis curves
- Modeling of rate-dependent phenomena in hysteretic actuators due to eddy current effects by a novel extension of the Preisach model
- Fast inversion algorithm for Preisach-type model to compute control signals for tracking specified output trajectories.
- New Hamilton-Jacobi theory for robust control of hysteretic systems
Harvard - Boston University - University of Maryland
Sectional view of the Etrema magnetostrictive actuator
Harvard - Boston University - University of Maryland
Higher Order Geometric Integrator— Performance Comparision
Comparison of integration schemes on a 2 by 2 by 4 grid, using the result of RK4 with much smaller stepsize as the benchmark. RK4: Runge-Kutta 4-th order, MP: Mid-point rule. Cay_RK4: Cayley transform with RK4.
Harvard - Boston University - University of Maryland
Higher Order Geometric Integrator— Performance Comparision
Comparison of performance on norm preserving
Harvard - Boston University - University of Maryland
Higher Order Geometric Integrator— Summary of Features
• Fast
– Explicit
– On the right track
• Accurate due to high order
• Norm preserving
Method Stepsize (sec.) Time (sec.)RK4 2 10 -13 1656RK4 6 10 –13 953
Mid-Point 6 10 –13 789 Cayley-RK4 6 10 –13 367