Customer Solutions
Integrated PXI System for Multihead X-ray Tube Stress Testing
Author(s):
V. Arunachalam, Soliton Automation Private Limited
Industry:
Life Science
Product:
Compact FieldPoint, Distributed I/O, FieldPoint, LabVIEW, Modular Instruments, Oscilloscopes/Digitizers, PXI/CompactPCI
The Challenge:
Developing a Highly Accelerated Stress Test system (HAST) in the shortest possible time for independent, simultaneous endurance testing of two X-ray systems controlled by CAN and serial communication.
The Solution:
Creating an integrated system using the PXI platform with multiport CAN interfaces and serial interfaces for communication with the different X-ray systems and high speed digitizers to acquire the fault waveforms.
Introduction
Our customer, a leading manufacturer of X-ray system components for medical applications, designed new varieties of X-ray tubes for different applications. After the customer designed the new X-ray tubes, they needed to test the new X-ray system for endurance and validation before transferring it to manufacturing. The critical HAST testing involves exposing the tubes to X-ray cycles of varying intensity and duration continuously for up to ten days and validating the various design parameters. The HAST provides valuable information to the design team on the system’s reliability, performance, and design validation. After we completed the design and defined the validation parameters, our customer asked us to develop a HAST station in the shortest possible time to simultaneously test two X-ray tubes. To fulfill the complex requirements, we decided to use an integrated solution and chose the PXI/LabVIEW system.
System Requirements
Our customer needed to control each X-ray system through CAN communication to set the exposure parameters according to test protocols. With a serial interface to each X-ray system, our customer could read the values measured by the manufacturer’s measurement system, which we used to validate the system. We used an additional serial interface to each generator for fault monitoring and resetting the system after a fault.
Additionally, we validated the X-ray tubes based on the occurrence of ‘spits’ or arcing caused by dielectric breakdown in the X-ray tube. We measured and recorded the temperature at specified locations on the X-ray system. The systems also required alarms and safety interlocks through software.
System Description
The PXI instrumentation platform integrated all of the desired functionality to simultaneously and independently perform HAST on two units at a time. We used a two-port PXI CAN interface for CAN communication. A four-port PXI serial interface provided serial communication with the test system and the X-ray measurement system. Four 100 MHz PXI oscilloscopes perform the high-speed data acquisition of spit waveforms from the anode and cathode of each X-ray tube. FieldPoint thermocouple and discrete I/O modules measure temperature and implement safety interlocks respectively. The system interfaces to a PC using a MXI interface. A LabVIEW application controls the overall tests and data management. The test system interfaces to a second PC running a Web server and a database.
System Development
Powered by LabVIEW and the appropriate drivers from National Instruments, we quickly developed the multiple CAN and serial interface communication. The customer used the simple user interface to define the test parameters and view the results.
The spit detection posed a tougher challenge. A spit characterizes a sudden dip in the applied voltage to the X-ray tube. Spits can occur at two positions (anode and cathode) in each station, simultaneously or separately, and at any time during the exposure. This meant that the customer needed the ability to trigger on any of the four channels when a spit occurred. Because the customer wanted the ability to resolve the spit waveform finely, we used four 100 MHz PXI scopes to trigger on a falling edge and used software algorithms to differentiate between a spit and the end of exposure. With the PXI architecture, we integrated waveform acquisition and analysis to perform the necessary feedback control to stop the test if the spits exceeded a preset limit. We monitored the temperature and safety interlocks for test chamber door status and incoming power using FieldPoint modules.
We uploaded the test data and the HAST system status information into a database server running on a second PC using the SQL toolkit. A Web server on this PC made this information available to the global teams interested in this data. Authorized users had the access to shut the system down via the Web. By moving the database and Web server activity into a second PC, we ensured people trying to access the system status and data would not disturb the HAST. This was important because the PC running the HAST software performed high-speed data acquisition (DAQ) and analysis. Using the Enterprise Connectivity Toolset features, we programmed the second PC to send e-mails to the engineers on the test status, reports, and any critical events.
System Benefits
We easily integrated PXI, FieldPoint, CAN, high-speed DAQ, multi-port RS-232, temperature measurement, and the digital I/O required for the system. The LabVIEW environment combined with NI driver software provided seamless integration and application development. The alternative design involved using four separate oscilloscopes and two separate PCs for control of the X-ray system - but this system would not integrate all of the required functionality.
With LabVIEW, we developed the complex application that used CAN, serial, and high-speed DAQ to meet our tight deadline. We estimate that we saved one man-year of development efforts compared to previous attempts to automate similar processes (especially the spit detection) using alternative methods.
By eliminating the high-end, stand-alone oscilloscopes and integrating all functionality, we saved more than $30,000. In addition, we saved space, which is always at a premium in a fast growing manufacturing site. However, the most significant savings were from the quick completion of the project.
The Web-enabled system provided the global teams with access to the HAST status and results online. Furthermore, with the features of the Enterprise Connectivity Toolset, the customer could instantaneously e-mail or mobile phone message critical results.
Conclusion
Our customer needed a reliable solution developed in a short time period. The combination of FieldPoint, LabVIEW, and PXI helped us develop a user-friendly solution within a very short timeframe. The HAST station deployed within eight weeks and the customer ran the HAST and validated their product successfully.
For more information, contact:
V. Arunachalam
Senior Project Manager
Soliton Automation Private Limited
Classic Towers, 1547 Trichy Road
Coimbatore - 641018 INDIA
Tel: +91 (422) 302374
E-mail: arun@solitonautomation.com
v_arunachalam_pc_rd_2002.pdf
View the entire user solution in Adobe Acrobat PDF format.
