Karl Reichard

Calibration-based phase-shifting projected fringe profilometry for accurate absolute 3D surface profile measurement

In this paper, an accurate calibration-based phase-shifting measurement technique for measuring the absolute 3D surface profiles is presented, in which the system distortions for each detection location are calibrated individually. Thus, this approach offers higher accuracy than that of conventional global system model-based calibration technique. By comparing the experimental results from this technique with the data from Zeiss Universal Precision Measuring Center (Model UPMC 550), it is found that the absolute measurement accuracy for a bowl size object (about 160 mm in diameter and 40 mm in depth) is about 5 μm. This experimental result proves that, indeed, this calibration-based phase-shifting measurement technique has a good enough accuracy for precise engineering surface (such as gear gauge surface) measurement.

Application of sensor fusion and signal classification techniques in a distributed machinery condition monitoring system

A new paradigm for machinery maintenance is emerging as preventive maintenance strategies are being replaced by condition-based maintenance. In condition-based maintenance, machinery is repaired or serviced only when an intelligent monitoring system indicates that the system cannot fulfill mission requirements. The implementation of such systems requires a combination of sensor data fusion, feature extraction, classification, and prediction algorithms. In addition, new system architectures are being developed to facilitate the reduction of wide bandwidth sensor data to concise predictions of ability of the system to complete its current mission or future missions. This paper describes the system architecture, data fusion, and classification algorithms employed in a distributed, wireless bearing and gear health monitoring system. The role and integration of prognostic algorithms--required to predict future system health--are also discussed. Examples are provided which illustrate the application of the system architecture and algorithms to data collected on a machinery diagnostics test bed at the Applied Research Laboratory at The Pennsylvania State University.

Bend-insensitive ultra short long-period gratings by the electric arc method and their applications to harsh environment sensing and communication

Ultra short long-period gratings (LPGs) fabricated using the electric arc discharge method are demonstrated with regular single-mode fibers. The gratings were as short as two periods, which were the shortest LPGs ever reported. The evolution of this short gratings and their characteristics are investigated in this paper. The excellent bending insensitivity and high temperature robustness demonstrated by this unique LPG make it particularly suitable for harsh environment sensing and communication.

A new design for non-zero dispersion-shifted fiber (NZ-DSF) with a large effective area over 100 μm2 and low bending and splice loss

A new design for large-effective-area non-zero dispersion-shifted fiber (NZ-DSF) for dense wavelength division multiplexing (DWDM) is presented. The Gaussian approximation method is used for calculating electrical field distribution for the designed refractive index profile. The designed fiber has a dispersion about 4 ps/nm/km and dispersion slope about 0.06 ps/nm2/km at 1.55 μm operating wavelength, which can be used to avoid four-wave mixing (FWM). In addition, our calculation also shown that the designed fiber not only has a large effective area over 100 μm2 but also has low bending loss (<1.3×10−3 dB with 30 mm bending radius and 100 turns) and low splice loss (<6.38×10−3 dB) with conventional fiber. The manufacturing tolerance of the fiber is found to be compatible with other types of known profile large-effective-area fibers. Thus, this newly designed fiber may be a good candidate for the long-haul DWDM fiber optic communications.

Using torsional vibration analysis as a synergistic method for crack detection in rotating equipment

A non-intrusive torsional vibration method for monitoring and tracking small changes in crack growth of reactor coolant pump shafts is presented in this paper. This method resolves and tracks characteristic changes in the natural torsional vibration frequencies that are associated with shaft crack propagation. The focus of this effort is to develop and apply the torsional vibration shaft cracking monitoring technique on a Westinghouse 93A reactor coolant pump. While this technique is being applied to reactor coolant pumps, it is generally applicable to many types of rotating equipment, including centrifugal charging pumps, condensate and feed water pumps, and may be used to detect and track changes in blade natural frequencies in gas or steam turbines. A laboratory scale rotor test bed was developed to investigate shaft cracking detection techniques under controlled conditions. The test bed provides a mechanism to evaluate sensing technologies and algorithm development. For accurate knowledge of the crack characteristics (crack depth and front), a sample shaft was seeded with a crack that was propagated using a three-point bending process. Following each crack growth step, the specimen was evaluated using ultrasonic inspection techniques for crack characterization. After inspection, the shaft was inserted in the rotor test bed for analysis and to track changes in shaft torsional vibration features. The torsional vibration measurement method has demonstrated the ability to reliably detect changes in the first natural shaft frequency in the range of 0.1 to 0.2 Hz. This technique shows the potential to enable online structural health diagnostics and ultimately the prevention of shaft or even possibly blade failure due to crack growth.

Utilizing dcom in an open system architecture framework for machinery monitoring and diagnostics

A communications framework for nextgeneration machinery monitoring and diagnostic systems has been addressed through the Open System Architecture for Condition Based Maintenance (OSA-CBM) development team. This framework employs the use of an open system architecture standard utilizing a distributed software model approach. The OSA-CBM team investigated different middleware technologies and defined data models in C O D A and COMIDCOM as well as XML. Even though IDL files are provided, the protocol logic or skeleton code isn’t defined; only conceptual descriptions are provided. The Applied Research Laboratory (a) has taken the COIWDCOM IDL files along with supporting OSA-CBM documentation and has developed skeleton code to implement a functional CBM system. This work focused on writing the necessary handshaking and data management code needed for communications between OSA-CBM modules. From this work, a user can develop their own working version and expand the theory to all other OSA-CBM layers. This paper provides an overview of the OSA-CBM development models and insight into a DCOMbased OSA-CBM implementation. TABLE OF CONTENTS

Model-based Prediction of Skid-steer Robot Kinematics Using Online Estimation of Track Instantaneous Centers of Rotation

This paper presents a kinematic extended Kalman filter EKF designed to estimate the location of track instantaneous centers of rotation ICRs and aid in model-based motion prediction of skid-steer robots. Utilizing an ICR-based kinematic model has resulted in impressive odometry estimates for skid-steer movement in previous works, but estimation of ICR locations was performed offline on recorded data. The EKF presented here utilizes a kinematic model of skid-steer motion based on ICR locations. The ICR locations are learned by the filter through the inclusion of position and heading measurements. A background on ICR kinematics is presented, followed by the development of the ICR EKF. Simulation results are presented to aid in the analysis of noise and bias susceptibility. The experimental platforms and sensors are described, followed by the results of filter implementation. Extensive field testing was conducted on two skid-steer robots, one with tracks and another with wheels. ICR odometry using learned ICR locations predicts robot position with a mean error of -0.42i¾?m over 40.5i¾?m of travel during one tracked vehicle test. A test consisting of driving both vehicles approximately 1,000i¾?m shows clustering of ICR estimates for the duration of the run, suggesting that ICR locations do not vary significantly when a vehicle is operated with low dynamics.

Zeros of modal models of flexible structures

It is shown that in some situations the zero patterns of a flexible structure change radically with model order. The refinement of the model by the addition of higher-order modes can cause zeros to appear at low frequencies or in the right half-plane. Structures instrumented with piezoelectric actuators and/or fiber-optic sensors are also considered. >

Investigation of tuning characteristics of electrically tunable long-period gratings with a precise four-Layer model

In this paper, an investigation of the tuning characteristics of electrically tunable long-period gratings (LPGs) is presented. A precise four-layer model is used to quantitatively analyze the tuning potential of the gratings, and experimental data are provided to support the analysis. The four-layer model includes a silica core layer with an inscribed LPG, a thin silica cladding layer (/spl sim/40 /spl mu/m), an ultrathin (/spl sim/ 50 nm) high refractive index indium-tin dioxide (ITO) inner electrode layer, and a tunable electrooptic (E-O) polymer layer. It has been found that the inner electrode layer, made of high refractive index ITO, can be modeled as a high refractive index overlay and causes the forward-propagating modes in the thin silica cladding to reorganize as the ambient refractive index changes. This reorganization effect can lead to a significant increase (ten plus fold) in the tuning range of LPG tunable filters. Moreover, the required specifications of the tunable polymer layer are quantitatively analyzed. Finally, the required characteristics of the E-O polymer is realized by using a nanocomposite ferroelectric relaxor poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) terpolymer.

High-performance nonscanning Fourier-transform spectrometer that uses a Wollaston prism array

A high-performance nonscanning Fourier-transform spectrometer is reported that is composed mainly of a Wollaston prism array and a two-dimensional photodetector array. It is a substantial improvement over existing Wollaston prism based nonscanning Fourier-transform spectrometers because it offers finer spectral resolution and smaller size. Such spectrometers will find important applications in remote chemical and biological sensing, environmental monitoring, medical diagnosis, etc. Experimental results are consistent with theoretical analyses.