Glenn Y. Masada

Robust fault detection in nonlinear systems using sliding mode observers

A model-based scheme for robust detection and isolation of faults in a twin continuously-stirred tank reactor is presented. The scheme uses sliding mode observers for robust fault detection in the presence of parameter uncertainties in the system model. The fault detection and isolation scheme is validated by simulated faults in the sensors, actuators and plant operating parameters. The fault detection and isolation technique based on sliding mode observers is shown to be robust to parameter uncertainty in the model. The technique also provides a method for estimating the parameter error in the system.<<ETX>>

A neural network based adaptive fault detection scheme

An adaptive neural network augmented observer for fault detection in nonlinear systems is presented. The key feature of this fault detection scheme is the use of a sliding mode observer to characterize the unmodeled dynamics, and facilitate the training of the neural network. The scheme provides robust fault detection in the presence of modeling errors. The fault detection scheme is validated by simulating faults in a section of a thermal power plant model. Simulations show that the adaptive fault detection scheme learns the unmodeled dynamics, and is able to distinguish between faults, and modeling errors.

Mechanical response of PCB assemblies during infrared reflow soldering

A finite element structural model is developed to predict the thermomechanical behavior of printed circuit board (PCB) assemblies during infrared reflow soldering. Specifically, the model predicts the amount of board warpage, the effects of increased PCB assembly stiffness resulting from the solder joint formation, and the size of gaps generated at the module lead solder pad interface. In this paper, quantitative estimates of these process-induced variables are provided as well as a description of the approach used for the analyses.

Thermocompression bonding effects on bump-pad adhesion

In the wafer bumping process, metal bumps are deposited on aluminum pads and are later used to bond the silicon die to the I/O connections. The bump strength is important for the mechanical integrity and overall reliability of the interconnect. In this paper the effects of the following thermocompression bonding parameters on the bump-pad adhesion of TAB (tape automated bonding) bonds are experimentally determined and analytically explained: thermode temperature, base temperature, bonding pressure, and bonding duration. Experiments were performed on a 328-lead TAB device (gold bump on 4-mil pitch) and were based upon a 4-parameter, 3-level, Taguchi orthogonal array. The experimental results are compared with results obtained from finite element analyses. A consistent increase in the bump strength was observed after thermocompression bonding. Applied thermode pressure and bonding duration were found to be the most significant parameters that affect bump-pad adhesion. >

Model of a hyperelastic thin plate using the extended bond graph method

Abstract In this paper, an extended bond graph method is used to analyze the vibration of a hyperelastic plate. The development of the two-dimensional model is outlined in detail using the theory of conjugate projection in continuum mechanics. The natural frequencies computed from the bond graph analysis are compared to those from a finite element analysis and show excellent agreement in the fundamental mode. The utility of the bond graph model is illustrated by the ease of adding damping elements to the undamped plate. The extended bond graph method allows for wide ranges of continuous media to be reticulated in bond graph form.

Structural Analysis and Optimization of Nonlinear Control Systems Using Singular Value Decomposition

Structural information of a system/controller allows a designer to diagnose performance characteristics in advance and to make better choices of solution methods. Singular value decomposition (SVD) is a powerful structural analysis tool for linear systems, but it has not been applied to nonlinear systems. In this paper, SVD is used to structurally analyze and to optimally design nonlinear control systems using the linear algebraic equivalence of the nonlinear controller. Specifically, SVD is used to identify control input/output mode shapes, and the control input/output distribution patterns are analyzed using the mode shapes. Optimizing control effort and performance is achieved by truncating some mode shapes in the linear mode shape combinations. The proposed method is applied to the temperature control of a thermal system, and design guidelines are provided to overcome input-constraint-violating solutions.

Extended Bond Graph Reticulation of Piezoelectric Continua

Extended Bond Graph (EBG) reticulations for general and linear piezoelectric continua are developed in this paper. The EBG formulation is especially advantageous for modeling the distributed coupled electromechanical effects of these materials and for combining this representation with other discrete models. The electromechanical coupling effects are represented by a multiport C-element for the general piezoelectric material. For linear constitutive properties, the coupling effects are represented by two multiport C-elements; one for the strain energy and the other for the capacitance storage, and a transformer that converts the power flows between the two energy domains. Details of the developments of the general formulation and of the specific models are provided. This work represents the first application of EBGs to electric fields.

Sliding control retrofit for a thermal power plant

Preliminary results of a sliding mode controller retrofit for a thermal power plant are presented. The proposed sliding mode controller replaces the existing multi-loop PID controller on the water/steam side of the thermal power plant. The choice of the sliding mode control scheme is appropriate as it embodies an inherent robustness to modeling errors and parameter variations. The sliding mode controller is validated by simulations using a 21/sup st/ order thermal power plant model.

Dynamic Analysis of Flexible Bodies Using Extended Bond Graphs

An Extended Bond Graph (EBG) formulation is described for analyzing the dynamics of a flexible multibody system. This work extends the EBG method, which was originally developed for systems with small spatial motion, to rigid and flexible multibody systems exhibiting large overall motions. The development uses modular models for the elements so that complex system models can be derived by coupling these modules. The EBG formulation for moving reference frames is used to derive models of one-link and two-link flexible manipulator systems. This approach has several advantages over the Lagrangian and Newtonian methods, such as its ability to solve the forward and inverse dynamic problems using the same bond graph. Finally, the EBG formulations for cantilever beams and for multi-rigid body dynamic systems are shown to be special cases of the general EGBs for flexible bodies.

Dynamic analysis of a two-link flexible manipulator system using Extended Bond Graphs

Abstract The Extended Bond Graph (EBG) method is used to model a two-link flexible manipulator system. An EBG module is first derived to represent the dynamics of an elastic link undergoing large motions by applying the spatial discretization of the conjugate variable approximation method, the shadow-beam kinematic description and the principle of virtual work. Then, modules for a DC motor and a revolute joint are reticulated into the EBG format. Finally, the link, revolute joint and DC motor modules are coupled to form the EBG model for a two-link flexible manipulator system. Numerical simulations for a planar two-link flexible manipulator are presented, and the utility of this method is illustrated by the computation of the actuator torques and reaction forces at the joints.