@article {
	title = {Control of Hysteresis in Smart Actuators with Application to Micro-Positioning},
	author = {Tan, Xiaobo., Baras, John S., Krishnaprasad, P S.},
	year = {2005},
	month = {05/2005},
	abstract = {Hysteresis in smart material actuators makes the effective use of these actuators quite challenging. The Preisach operator has been widely used to model smart material hysteresis. Motivated by positioning applications of smart actuators, this paper addresses the value inversion problem for a class of discretized Preisach operators, i.e., to find an optimal input trajectory given a desired output value. This problem is solved through optimal state transition of a finite state machine (FSM) that corresponds to the discretized Preisach operator. A state-space reduction scheme for the FSM is developed, which significantly saves the memory and the computation time. Experimental results on micro-positioning control of a magnetostrictive actuator are presented to demonstrate the effectiveness of the proposed approach.},
	pages = {pp. 483-492},
	volume = {Volume 54},
	number = {Issue 5},
	journal = {Systems \&amp; Control Letters}
}
@conference {
	title = {A dynamic model for magnetostrictive hysteresis},
	author = {Tan, Xiaobo., Baras, John S., Krishnaprasad, P S.},
	year = {2003},
	month = {06/2003},
	abstract = {The rate-dependent hysteresis present in thin magnetostrictive actuators can be captured by a dynamic model, consisting of a Preisach operator coupled to an ordinary differential equation in an unusual way. The model presents interesting problems in analysis and computation due to its special structure. In this paper, we first transform the model into a more amenable form and gain insight into the model by introducing a new hysteretic operator. Then we investigate some system-theoretic properties of the model: stability of equilibria, input-output stability, reachability~and observability. Existence of periodic solutions under periodic forcing is also established. Finally, numerical integration schemes for the model are discussed.},
	address = {Denver, Colorado},
	booktitle = {2003 American Control Conference},
	pages = {pp. 1074-1079}
}
@conference {
	title = {Computational Micromagnetics for Magnetostrictive Actuators},
	author = {Tan, Xiaobo., Baras, John S., Krishnaprasad, P S.},
	year = {2000},
	month = {05/2000},
	abstract = {Computational micromagnetics plays an important role in design and control of magnetostrictive actuators. A systematic approach to calculate magnetic dynamics and magnetostriction is presented. A method is developed to solve the coupled Landau-Lifshitz-Gilbert equation for dynamics of magnetization and the 1-D elastic motion equation. A hierarchical algorithm using multipole approximation speeds up the evaluation of the demagnetizing eld, reducing computational cost from O(N2) to O(NlogN). A hybrid 3D-1D scheme is adopted to compute the magnetostriction. Numerical results include domain wall dynamics, hysteresis, magnetostriction, and applications to control of actuators.},
	address = {Philadelphia, Pennsylvania},
	booktitle = {3rd SIAM Conference on Mathematical aspects of Materials Science}
}
@conference {
	title = {Fast Evaluation of Demagetizing Field in Three Dimensional Micromagnetics Using Multipole Approximation},
	author = {Tan, Xiaobo., Baras, John S., Krishnaprasad, P S.},
	year = {2000},
	month = {03/2000},
	abstract = {Computational micromagnetics in three dimensions is of increasing interest with the development of magnetostrictive sensors and actuators. In solving the Landau-Lifshitz-Gilbert (LLG) equation, the governing equation of magnetic dynamics for ferromagnetic materials, we need to evaluate the effective field. The effective field consists of several terms, among which the demagnetizing field is of long-range nature. Evaluating the demagnetizing field directly requires work of O(N2) for a grid of N cells and thus it is the bottleneck in computational micromagnetics. A fast hierarchical algorithm using multipole approximation is developed to evaluate the demagnetizing field. We first construct a mesh hierarchy and divide the grid into boxes of different levels. The lowest level box is the whole grid while the highest level boxes are just cells. The approximate field contribution from the cells contained in a box is characterized by the box attributes, which are obtained via multipole approximation. The algorithm computes field contributions from remote cells using attributes of appropriate boxes containing those cells, and it computes contributions from adjacent cells directly. Numerical results have shown that the algorithm requires work of O(NlogN) and at the same time it achieves high accuracy. It makes micromagnetic simulation in three dimensions feasible},
	address = {Newport Beach, CA},
	booktitle = {7th SPIE International Symposium on Smart Structures and Materials},
	pages = {pp. 195-201}
}
@conference {
	title = {Computational Micromagnetics for Magnetostrictive Actuators},
	author = {Tan, Xiaobo., Baras, John S., Krishnaprasad, P S.},
	year = {2000},
	month = {03/2000},
	abstract = {Computational micromagnetics plays an important role in design and control of magnetostrictive actuators. A systematic approach to calculate magnetic dynamics and magnetostriction is presented. A method is developed to solve the coupled Landau-Lifshitz-Gilbert equation for dynamics of magnetization and the 1-D elastic motionequation.},
	address = {Newport Beach, CA},
	booktitle = {7th SPIE International Symposium on Smart Structures and Materials},
	pages = {pp. 162-173}
}
@conference {
	title = {Dynamic Observers as Asymptotic Limits of Recursive Filters},
	author = {Baras, John S., Krishnaprasad, P S.},
	year = {1982},
	month = {12/1982},
	abstract = {~

In this paper we discuss the ansatz: nonlinear observer = limit of nonlinear filter. The results of Vent-tsel{\textquoteright} and Freidlin on large deviations are useful in interpreting observer trajectories as {\textquoteright}most-likely{\textquoteright} paths.},
	address = {Orlando, Florida},
	booktitle = {21st IEEE Conference on Decision and Control},
	pages = {pp. 1126-1127}
}
