Overview

The use of Prosig P5000, P8000 and DATS systems within the NVH Engineering Groups at Ford Motor Company in Dearborn has made it possible to significantly reduce the time needed for the testing and analysis required for NVH target evaluation and development. Improvement factors of greater than 5 have been achieved relative to conventional procedures involving recording data with tape recorders and analyzing the results on laboratory analyzers.

Automotive manufacturers feel the ups and downs of economic cycles faster and more deeply than possibly any other industry. For this reason, automotive companies and their suppliers have made process improvements in every area possible over the past 20 years. One such area is the resource intensive product development and testing phase. Improvements in vehicle R&D testing processes have helped reduce the time and costs involved, without adversely affecting the equally important consistency of data quality.

Prosig's P8000/DATS data acquisition and analysis system has many features which can assist NVH (Noise, Vibration and Harshness) groups in achieving productivity improvements, particularly when applying the same tests in their multi-platform vehicle studies. Savings are achieved not only in the acquisition and analysis processes, but by improvements in test consistency.

Through organized implementation and collective usage, Ford was able to make substantial savings in vehicle NVH testing. Ford achieved this goal by taking advantage of the flexibility of DATS to operate either as an interactive analysis tool for vehicle development or as an automated procedure for repetitive testing, primarily for comparative analysis and quality control.

Data Acquisition

Vehicle NVH testing involves instrumenting the interior of a car or truck with microphones and accelerometers. NVH Engineers need to measure sounds and vibrations at various points in the vehicle interior. Additionally, signals need to be derived from chassis, body and powertrain components that contribute to interior NVH phenomena. Typically, transducer counts will vary from 2 up to 16 or more. Every P8000 can be confuigured with anything from 4 to 48-channels of simultaneously sampled 24-bit ADC's, each with programmable gain, offset, anti-alias filters and transducer power. Multiple units can be combined to extend the channel count up to 1024. Tacho inputs are included as standard.

Most systems are configured with either BNC or Lemo connectors for direct connection to microphones and accelerometers. Optional P8000 modules are available for a wide variety of applications including thermocouples, CAN-bus, charge accels, high speed precision tachos, load cells, pressure transducers and so on.

The compact size of the P8000 saves space, while eliminating the need for external signal conditioning.

The P8000 operates on vehicle voltage, and draws a low current of under 3 amps per 8-channel unit.

The P8000 acquires data at rates up to 400k samples per second per channel.

Data is streamed directly to the host PC via USB2 enabling long duration acquisitions.

Consistent data acquisition is achieved with Prosig's DATS Acquisition software that sets up the P8000 unit for the required transducer configuration, signal conditioning and capture rate as well as the test duration and data file naming. Setup files can be saved and loaded afterwards for a variety of tests. The setup information includes critical elements such as transducer ID, dB reference, and Project Manager information about the vehicle and type of test. For QA tracking, this and other setup file information are saved with the captured signals as Named Elements. This is information is critical not only for QA tracking, but is also used in smart signal labeling and in DATS Intaglio automated report-generation facility.

DATS Acquisition provides facilities that help the engineer install and check out the transducers. These include single channel monitoring with scope-like displays in both the time and frequency domains, and various types of calibration procedures. Multi-channel monitoring and automatic gain ranging are also provided to simplify pre-run checkout. TEDS type transducers are supported and the acquisition software includes an integrated transducer database.

During the acquisition run the user can choose to display the over-range status of each channel and also view up to eight signals that can be individually switched between time or frequency domain displays.

Run Control screen elements during acquisition

Ford Motor Company NVH engineers now use automated scripting to set up their acquisition systems. Adopting standardization in this area has improved consistency in the quality of captured data over a wide range of vehicle tests.

Data Analysis

As with data acquisition, a true consistency in data analysis is needed to achieve comparative results between vehicles being tested. To achieve this end Ford test-engineers use signal-processing scripts to automate the analysis of captured data. This gives an added productivity bonus in that the Prosig DATS script automation brings dramatically reduced data processing times.

Using DATS software scripting, data can be acquired on the test track, analyzed using a task-specific script and the results presented in a report in Microsoft Word format prepared by the automatic report generator.

Alternatively, a script can directly enter results into Microsoft Excel documents. By the time the engineer has returned from the track the acquired data has been saved, analyzed, and a report automatically produced on all the signals. Although test procedures often demand several runs be carried out, the scripts are able to process all of the data from a single invocation.

The portability of the Prosig P8000/DATS system is invaluable in allowing the engineer to acquire and analyze the data directly in the vehicle. First and foremost, this examination can be used to ensure that the test data is good. It also allows the engineer to view the results of the analysis and quickly make a change to the vehicle component under test. New data can then be acquired and analyzed for comparison with the old.

George Chang, Prosig USA Technical Director has worked closely with the customer in implementing their deployment of the P5600/DATS system. George states, "By creating a set of standard DATS analysis scripts, the NVH test engineers are enabled with an easy-to-use set of signal-processing tools for a complete range of tests within a variety of vehicle platforms. This uniform analysis approach has assisted Ford NVH engineering groups in achieving consistent data analysis for vehicles in the development process and for vehicles across the entire range right through to production".

Automated reporting

Prosig's automated report generator is called Intaglio, and is a standard part of DATS software. Using Intaglio, NVH engineers can create standard report templates with Microsoft Word for each of the various tests. Graphs, processed results and project information fields relevant to each test are then inserted automatically at run-time by the Intaglio program.

DATS Intaglio report scripting saves a significant amount of time in the report generation process. Not only does it take selected signals from data runs, but it also applies layouts that properly scale, and label the signal graphs automatically. Intaglio also makes use of DATS Named Elements that are attached to each signal and can be added to by subsequent processing. Named Elements can be used to hold setup information defining the acquisition stage, project information such as VIN number, processing information such as types of windowing and filter frequencies, and analysis information such as Sound Quality calculations of Sones, Phons, or Articulation Index. When an Intaglio script is running, the user can watch it opening the desired report template and dynamically updating the graph and text fields in the document.

Intaglio is far more powerful than a traditional cut-and-paste method, because it allows DATS to be invoked from within the report, so that it can change scaling and other visible attributes dynamically using the original data. This clearly allows greater flexibility than dealing with a fixed image in a document. The ability to have active control of data presentation using DATS is not only an essential feature of the report generation process but is also a valuable tool to aid the preparation of one-off reports.

Above is a mockup of a simple report template. Note the placeholders for the two graphs, and the areas for Named Elements to be inserted as encloses by [DRIVER], [COMPANY] and [DATE].

Below is the completed Intaglio report. The graphs and Named Elements have been automatically inserted in the respective placeholder locations. The graphs have also had pre-defined layouts applied to allow for signal overlays with trace colors, and styles, while labels have been applied. The [NAME], [COMPANY] and [DATE] fields have been filled in with corresponding Named Element information.

To sum up, the Prosig P5600/DATS system has assisted Ford NVH engineers in implementing a system of standardized development tests and reports. This has supported the achievement of required data quality and has resulted in significantly reduced cycle times for testing, analyzing and reporting results.