National Instruments PXI Platform Research Articles

FPGA Hardware Implementation of DOA Estimation Algorithm Employing LU Decomposition

In this paper, authors present their work on field-programmable gate array (FPGA) hardware implementation of proposed direction of arrival estimation algorithms employing LU factorization. Both L and U matrices were considered in computing the angle estimates. Hardware implementation was done on a Virtex-5 FPGA and its experimental verification was performed using National Instruments PXI platform which provides hardware modules for data acquisition, RF down-conversion, digitization, etc. A uniform linear array consisting of four antenna elements was deployed at the receiver. LabVIEW FPGA modules with high throughput math functions were used for implementing the proposed algorithms. MATLAB simulations of the proposed algorithms were also performed to validate the efficacy of the proposed algorithms prior to hardware implementation of the same. Both MATLAB simulation and experimental verification establish the superiority of the proposed methods over existing methods reported in the literature, such as QR decomposition-based implementations. FPGA compilation results report low resource usage and faster computation time compared with the QR-based hardware implementation. Performance comparison in terms of estimation accuracy, percentage resource utilization, and processing time is also presented for different data and matrix sizes.

The Automated System for Parametric and Functional Control of the Logic ICS

The article discusses implementation of the automated system based on the use of National Instruments PXI platform and designed for parametric and functional control of the logic ICs. The features of specialized software and typical results, obtained using the developed system, are observed.

An unsupervised learning algorithm for fatigue crack detection in waveguides

Ultrasonic guided waves (UGWs) are a useful tool in structural health monitoring (SHM)applications that can benefit from built-in transduction, moderately large inspectionranges, and high sensitivity to small flaws. This paper describes an SHM method based onUGWs and outlier analysis devoted to the detection and quantification of fatigue cracks instructural waveguides. The method combines the advantages of UGWs with the outcomesof the discrete wavelet transform (DWT) to extract defect-sensitive features aimed atperforming a multivariate diagnosis of damage. In particular, the DWT is exploited togenerate a set of relevant wavelet coefficients to construct a uni-dimensional ormulti-dimensional damage index vector. The vector is fed to an outlier analysis to detectanomalous structural states. The general framework presented in this paper isapplied to the detection of fatigue cracks in a steel beam. The probing hardwareconsists of a National Instruments PXI platform that controls the generation anddetection of the ultrasonic signals by means of piezoelectric transducers made of leadzirconate titanate. The effectiveness of the proposed approach to diagnose thepresence of defects as small as a few per cent of the waveguide cross-sectional area isdemonstrated.

LHC Collimators Low Level Control System

The low level control system (LLCS) of the LHC collimators is responsible for accurate synchronization of 500 axes of motion at microsecond level. Stepping motors are used in open loop ensuring a high level of repeatability of the position. In addition, a position survey system based on Resolver and LVDT sensors and operating at approximately 100 Hz, verifies in real-time the position of each axis with some tens of micrometers accuracy with respect to the expected position. The LLCS is characterized by several challenging requirements such as high reliability, redundancy, strict timing constraints and compactness of the low level hardware because of the limited space available in the racks underground. The National Instruments PXI platform has been proposed and evaluated as real-time low level hardware. In this paper the architecture of the LHC collimators LLCS is presented. The solution adopted for implementing motion control and positioning sensors reading on the PXI platform are detailed.