PC-Based System Tests Vehicles in Temperature Extremes

Early in 1995, when personnel at the Ford Electrical Fuel Handling Division discussed upcoming prototype vehicle testing in Yucca, AZ, the test trip was nothing new. But the proposed technique was: The company wanted to improve its methods of gathering and recording data.

At the time, Ford used a system that forced the test engineers to work in very cramped quarters. The system and the engineers were wedged into the passenger compartment along with the written test procedures, gauges, strip-chart recorders, data loggers, display units and engine-calibration equipment.

New System Plans

To meet the new test goals, Ford contracted with National Instrumentation and Engineering (NIE) to find a solution that would:

Reduce the time needed to analyze and process acquired data.

Display results immediately in convenient formats and charts.

Reduce the passenger-compartment clutter.

Perform remote monitoring and data retrieval from test vehicles.

Keep recorded data compatible with previous tests.

Ford engineering personnel, a manager and a supervisor, worked with NIE to combine the demands and requirements of the testing procedure into one piece of equipment. The solution was a custom PC-based system with a graphical user interface and plug-in data acquisition boards. We completed the system with the addition of Ford computer-based engine-calibration equipment.

The Software

We selected LabVIEW from National Instruments because it provided a fast, cost-effective way to develop a complete customer package (Figure 1). We programmed the system to log data at variable intervals or to acquire and display data taken at 100 kHz, excluding the stand-alone strip-chart recorder.

The information was displayed in graphs, charts and tables, and stored in standard spreadsheet format for later manipulation and analysis (Figure 2). We incorporated all schematics and system drawings into the program for viewing the prototype vehicle-under-test. Once the software was ready to meet the demands of test, it was time to work in a unique hardware system.

The Hardware

We developed a computer system to survive the punishing test environment. Shock and vibration, as well as temperature extremes ranging from 60° to 130°F, were just a few of the challenges.

The computer chassis was mounted on four shock absorbers in the trunk of the test vehicle to give the test engineers more room in the passenger compartment. All the internal components—boards, disk drives and a power supply—were also shock-mounted. Three high-volume fans moved filtered air into the computer chassis, keeping the components cool and maintaining a positive air pressure to keep out dust and debris.

We used the AT-MIO-16E-2 and AT-MIO-64E-3 data acquisition boards from National Instruments to measure temperatures, pressures, timing pulses and many voltages. The 5B Series modules were used for signal conditioning.

The unit was powered by either AC or DC and controlled from the passenger compartment with a remote switch. All signals were connected at the rear of the chassis. To meet the demand for remote communications, we used a cellular voice data modem that communicated between vehicles and remotely retrieved data and controlled the computer system.

By placing most of the data-gathering and recording equipment in the trunk of the vehicle, the test engineers shared the passenger compartment with only the display units and printers. The system displays, which came from Cascade Technology, provided color VGA display, a keyboard, a mouse and a reset button in one unit.

A single cable connected the display unit to the computer chassis. The display recorded and monitored many signals, including thermocouples, pressure transducers, voltages, pulses from engine rpm and vehicle-speed sensors.

Powering and Testing the System

An auxiliary battery powered the complete instrumentation system, which was charged by the charging system of the test vehicle. To test the prototype vehicle, the computer could disconnect itself as well as the auxiliary battery system from the vehicle-charging system.

With the new instrumentation system complete, it was time to evaluate it in the field. By operating in continual triple-digit Arizona temperatures during 12- to 14-hour days, the system got—almost literally—a baptism by fire. Under this grueling pace, Ford added tests and changed programs at least once a day, but the system successfully met the challenges throughout.

Epilogue

Since the Arizona tests, the system has operated flawlessly at -40°F. It is the only test system of this type at Ford that has been used over such a wide range of temperatures.

About the Author

Brian Wright is Manager of the Instrumentation and Electronics Systems Group at National Instrumentation and Engineering. The electrical engineer began his career in automotive testing more than nine years ago and has been at NIE for the last two years. National Instrumentation and Engineering, 12250 Belden Court, Livonia, MI 48152,

(313) 421-2151.

Brian Wright is Manager of the Instrumentation and Electronics Systems Group at National Instrumentation and Engineering. The electrical engineer began his career in automotive testing more than nine years ago and has been at NIE for the last two years. National Instrumentation and Engineering, 12250 Belden Court, Livonia, MI 48152,

(313) 421-2151.

Copyright 1996 Nelson Publishing Inc.

July 1996

 

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