Enterprise-Wide Generic Data Acquisition, Validation, and Storage System

Author(s):
Dennis Kenter - WAES

Industry:
Aerospace/Avionics

Products:
PXI/CompactPCI, LabVIEW

The Challenge:
Replacing our current paper-based system of test specifications with an electronic system.

The Solution:
Designing a generic test sequencer and test stand interface with software, such as LabVIEW and DataSocket capable of interpreting electronic test procedures.

Background
Woodward AES (WAES) is the industry's leading supplier of integrated engine fuel delivery systems. In the 1940s when the U.S. military flew its first turbine-powered aircraft, WAES helped the program take flight, providing the fuel controls critical to the mission's success. Today, we equip the most complex aircraft propulsion systems in the world with proven fuel control, injection components, and complete engine fuel delivery solutions.

Quality products are a baseline requirement for suppliers in the aircraft industry. The WAES reputation for dependability is a strong trait that drives our ongoing improvement efforts. It is why we adopted Six Sigma as a methodology, a mindset, and a way of doing business. As part of a Six Sigma quality initiative, we decided to replace our current paper-based system of test specifications with an electronic system. While we originally planned to ensure that we completed all test points and legibly store the data, the scope quickly widened because of the tremendous capabilities of the software and hardware. We not only eliminated the number-one cause for quality rejects, but we also improved the entire test process while molding consistency and completeness into the test specifications themselves. Additionally, we created a software and hardware package that is completely flexible in configuration, adaptable to many different platforms and systems, and generic enough that one version covers all applications. This alone will save hundreds of hours per year in programming, designing, troubleshooting, debugging, and building. In applying Six Sigma, we address customer expectations for cost, quality, and on-time delivery, while reducing scrap, rework, and throughput time.

System Overview
The solution is comprised of two main parts - a test sequencer and HMI/data source - and one connection element, which ties those parts together and a database. We defined the test sequencer as the electronic test specification procedure (ETSP) system and refer to the HMI/data source as the electronic test stand interface (ETSI) system. The database warehouses all the test specification procedures (TSPs) and stores data from completed tests. The ETSP and ETSI, coupled with the DataSocket server technology, provide the nucleus of the data collection and validation system. However, either can run independently.

In the Beginning, Before Test
We authored and maintained the test specifications in the ETSP system using an application attached to the company's enterprise resource planning (ERP) system. We performed this to facilitate revision control and engineering change releases. The TSP data is stored in an Oracle database. We used the SQL Toolkit and LabVIEW to write virtual instruments (VIs) that connect to the database, retrieve, and write information. On the Oracle side, we use a specially written database package that contains all the procedures that the ETSP software needs to execute. This includes writing data, retrieving TSP templates, and checking test status. The ETSP software executes these package procedures to perform database operations. This gives the LabVIEW software access to the database but leaves control of the database to its owners.
The validation functions necessary to verify the correctness, completeness, and structure of the TSP are performed in the ETSP software through a specially designed debugging function. The structure defines the order to complete the tests (individual test points each containing one recorded piece of data) and tasks (groups of tests). This structure that allows the ETSP computer to control sequencing, deleting and re-running, suspending, and resuming tests. Depending on type or mode in which the test is performed, the level of control enforced by the sequencer is automatically adjusted. For example, some modes allow multiple runs of the same test point, while others force strict adherence to the structure.

Multiple Functions with ETSP System
The ETSP system, in addition to being a test sequencer, has many other programmed functions. Some functions provide access to documentation and allow communications with auxiliary equipment such as the ETSI. The ETSP software is quite flexible, yet requires only one executable to run all our different products and programs. This greatly reduces the effort required to support the system as a whole. Being generic has proven to provide other advantages such as leveraging this system in other areas including the calibration laboratory.

By providing a direct connection between our database and the UUTs, the ETSP software can query and retrieve the latest approved revision of the TSPs at any location worldwide. This provides the means to affect instantaneous change at all locations. In the aerospace industry, all TSPs must be strictly controlled by revision letter and must have customer approval prior to use. It is paramount to maintain control over the use of the specifications to absolutely guarantee that only the most recent, approved TSP are used to ship product. Because the database warehouses the TSPs and also controls their status and revisions, we can guarantee that we use only approved released specifications.

Major Benefits of ETSP
The ETSP system offers distinct advantages over the paper-based system it replaced. The software, on completion of a test, writes a pass or fail to the test header in the database. This indicates the unit’s overall status to the quality auditors, which eliminates a detailed review of the tests. This, coupled with the guarantee that no test points have been omitted or illegibly written, will save hundreds, if not thousands, of hours per year.

Several data pages are published from every ETSP system through the use of the LabVIEW HTTP server built into the LabVIEW software. With these pages, the production leaders and customer service representatives can track the progress of UUTs via the Intranet. Using the ActiveX Web browser, online access to all referenced documents is just a click away. The ETSP system also:

• Eliminates microfilming (saves cost of film and time to process)
• Provides instantly retrievable data at all locations around the world
• Performs all calculations with GMath software (reduces human error)
• Stores complete data sets for SPC analysis (better quality management)
• Validates pass/fail criteria at every test point

ETSI - Providing the Data, HMI, and Much More
Where the ETSP system leaves off, the ETSI system takes over. As a second step in the overall conversion to electronic data, this system was designed to tie into and provide the data for the ETSP system. It also provides the HMI to all the instrumentation associated with each test stand. The computer connects via RS-232 and RS-485 ports to each device for all digital data and through the BNC-2115 and BNC-2110 for all analog data. The digital numbers are used to evaluate set conditions and record data, while the analog data provides a window into the real-time characteristics and operating conditions.

We designed the software for ETSI to accommodate any type and number of instruments. Its open architecture allows both the products tested on the stand and the instruments used during the test to be changed easily. We used two configuration files that define the equipment on the stand and the communication port configuration. Built-in editors provide access to these files for editing should a piece of equipment be added or removed. Through these files the auto-configuration software matches devices on the test stand with instruments that are required by the TSP. This in turn guarantees that only the tools required be displayed on screen, and they meet the accuracy requirements of the TSP.

The collection and reading of data is controlled through the VI Server. The first step is to create stand-alone subVIs for each instrument type. The essential attributes are to communicate to any number of identical instruments, have deterministic loop times, possess identical front panels, have very similar block diagrams, and be software controllable with respect to start, stop, and suspend commands. The subVIs are named and stored under their instrument type (make and model) within a directory dedicated to VI Server routines. When the file for port configuration is created, the software copies these subVIs and pastes them into the same directory under the name of the port for which they are created. Because the software determines what tools to populate on screen and knows the port where the instruments are located, the software loads and controls only the required subVIs through the VI Server.

Using the VI Server has proven extremely advantageous. The ability to load and control VIs separate from the main operating loop has several key qualities. First, it allows respectable iteration times (300 mSec) - previous state-machine software had loop times of 2.5 seconds or more. Second, because only the required subVIs are loaded, we conserve resources.

Putting It All Together
Using the DataSocket server, we joined the ETSP and ETSI systems and realized the true benefits. The ETSP system assumes authority over the ETSI system and forces it to reconfigure based on the instrument list sent via the DataSocket server. This way, the ETSP system can guarantee that the correct tools are configured and the data received is appropriate. Through the combination of ETSP and ETSI, we achieved greater control over the test process. Instead of just recording and verifying the pass/fail status of operator entered data, the ETSP system now validates and stores all set conditions and recorded data. Ultimately, this system will significantly reduce variability within the test process and help WAES in its pursuit to be a Six Sigma quality manufacturer.

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