Mehdi Ahmadian

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This study explores the use of generalized polynomial chaos theory for modeling complex nonlinear multibody dynamic systems in the presence of parametric and external uncertainty. The polynomial chaos framework has been chosen because it offers an efficient computational approach for the large, nonlinear multibody models of engineering systems of interest,(More)
This study applies generalized polynomial chaos theory to model complex nonlinear multibody dynamic systems operating in the presence of parametric and external uncertainty. Theoretical and computational aspects of this methodology are discussed in the companion paper " Modeling Multibody Dynamic Systems With Uncertainties. Part I: Theoretical and(More)
  • Mohammad H Elahinia, T Michael Seigler, Donald J Leo, Mehdi Ahmadian
  • 2004
In this paper a nonlinear stress-based controller is designed to position a single-degree-of-freedom shape memory alloy (SMA) actuated manipulator. A three-part model was constructed based on the dynamics/kinematics of the arm, the thermomechanical behavior of SMAs, and an assumed heat transfer model consisting of electrical heating and natural convection.(More)
(ABSTRACT) Vibratory gyroscopes are inertial sensors, used to measure rotation rates in a number of applications. The performance of these sensors is limited by imperfections that occur during manufacture of the resonators. The effects of resonator imperfections, in piezoelectric vibratory gyroscopes, were studied. Hamilton's principle and the Rayleigh-Ritz(More)
Orthogonal eigenstructure control is a novel active control method for vibration suppression in multi-input multi-output linear systems. This method is based on finding an output feedback control gain matrix in such a way that the closed-loop eigenvectors are almost orthogonal to the open-loop ones. Singular value decomposition is used to find the matrix,(More)
An orthogonal eigenstructure control method with collocated actuators and sensors was recently developed by the authors. In this paper the application of the method is extended beyond the collocation of the actuators and sensors, including the cases that different numbers of actuators and sensors are used. Orthogonal eigenstructure control is an output(More)
The characterization of damping is important in making accurate predictions of both the true response and the frequency response of any device or structure dominated by energy dissipation. The process of modeling damping matrices and experimental verification of those is challenging because damping can not be determined via static tests as can mass and(More)
Orthogonal eigenstructure control is used for designing a control law that decouples the dynamic modes of a flying vehicle. Orthogonal eigenstructure control is a feedback control method for linear time invariant multi-input multi-output systems. This method has been recently developed by authors. The advantage of this control method over eigenstructure(More)
Orthogonal eigenstructure control is a novel control method that recently has been developed by the authors as a method for active vibration cancellation. This method is a feedback control method, which is applicable to linear multi-input multi-output systems. The remarkable advantage of this method over most of the eigenstructure assignment methods is that(More)
  • Amnart Kanarat, Robert H Sturges, Mehdi Ahmadian, Donald J Leo, Charles F Reinholtz, Craig Woolsey +2 others
  • 2004
(ABSTRACT) This dissertation addresses the problem of motion planning and control for nonholonomic mobile robots, particularly wheeled and tracked mobile robots, working in extreme environments, for example, desert, forest, and mine. In such environments, the mobile robots are highly subject to external disturbances (e.g., slippery terrain, dusty air,(More)