Developing Test Systems for Automotive Multimedia Devices Using NI TestStand and PXI Hardware

Author(s):
Wilfried Noffz, Certified LabVIEW and NI TestStand Developer - NOFFZ ComputerTechnik
Dirk Schüller-Möller - NOFFZ ComputerTechnik
Christian Tenhumberg - NOFFZ ComputerTechnik

Industry:
Consumer Goods, Manufacturing, Electronics

Products:
Database Connectivity Toolkit, PXI-6052E, PXI-8420/4, PXI-1045, LabWindows/CVI, NI TestStand, PXI-1411, PXI-5431, PXI GPIB, LabVIEW

The Challenge:
Developing a test system for automotive multimedia systems that can perform multiple test operations for both DVD players and the associated display unity, and be easily altered to meet changing test parameters.

The Solution:
Using NI TestStand and LabVIEW software as well as NI PXI hardware to develop a test system for users to perform all of the required tests to ensure reliability and functionality for multiple types of in-vehicle entertainment systems.

Johnson Controls is an international components manufacturer for the automotive industry. One of its product lines includes automotive multimedia systems such as rear seat entetertainment systems. For DaimlerChrysler, these systems consist of a DVD player and two thin film transistor (TFT) displays installed in the headrests. Another variant developed for Opel is a foldout TFT display installed in the roof of the car.

Test System Requirements

Electronic module and device manufacturing requires test systems that are extremely reliable and flexible. High-quality products and minimal test system downtime and changeover time are extremely important in the automotive industry. In addition, hardware and software must be easily adaptable to new products and variants. Because Johnson Controls is a global company, worldwide test system component availability is also an essential aspect.

The required end-of-the-line test system needs to provide full DVD player testing, including both the AVS boxes and the associated TFT displays. Requirements also include testing for all electrical connections and optical and mechanical devices.

Comprehensive testing procedures include the following tests:

• Audio I/O including level, THD, and SINAD

• Current DVD player and display consumption

•  Plastic housing color control

•  Video I/O

• Display color homogeneity using the NOFFZ Display Test Toolkit

•  Keypad illumination color and function

•  Connection assemblies optical check power required to operate the keypad (MMI buttons)

•  Display hinge frictional force

•  Support for different manufacturers and types

•  TFT display parallel test (for the DaimlerChrysler variant)

 TAVT Test Platform

Based on these requirements, we developed the test system using the scalable telecommunications, audio, video, and telematics (TAVT) test platform. Because of the large variety of PXI modules, we configured the test system to meet various test product requirements.

A comprehensive interface electronics system provides the interface between the PXI modules, the test chambers, and test adapters, where we test the DVD players and TFT displays according to electrical, optical, and mechanical criteria. The power supply for the test samples is provided by high-quality, programmable power supply units with GPIB interfaces.

NI TestStand Offers a Modular, Flexible Software Structure

As a result of years of experience building test systems, we developed test libraries for audio and video tests, different communication interfaces, and vision and digital I/O that can be integrated into NI TestStand as custom step types. No special programming knowledge is required to use these step types because the test steps are easily configurable. We also expanded the NI TestStand environment with several service tools such as a limit editor, which acts as an interface between the customer’s database and the front end.

Display Test Toolkit

We integrated the NOFFZ Display Test Toolkit into NI TestStand to provide easy and configurable step types. NI TestStand makes it easy for the user to configure the individual test steps and adjust the test sequence so that the system can adapt to changing requirements.

The NOFFZ Display Test Toolkit offers the following test steps:

• Color and contrast test

• Pixel defect test

• Icon recognition

• Display adjustment

• Character recognition

Rear Seat Entertainment System Test Implementation

We designed all test adapters as interchangeable adapters because the system is used to test rear seat entertainment systems for different customers and setup times must be kept as low as possible. The test systems are located in separate test chambers because we conduct optical checks for both the DVD players and the displays.

The hardware features the following NI PXI devices:

• PXI-1045 chassis

• PXI-8176 embedded controller with GPIB interface

• PXI-6052E multifunction data acquisition module for analog measurements and signal generation

• PXI-5431 signal generator for generating video signals to test the display

• PXI-1411 image acquisition module for optical checks

• PXI-8420/4 serial interface

The test system supports the following bus systems:

• High-speed controller area network (CAN) buses

• Low-speed CAN buses

• Local interconnect network (LIN) buses

A comprehensive interface electronics system, with a general-purpose I/O (GPIO) card at the core, complements the system and includes the following:

• Power control

• Signal control

• Video multiplexer

• Video demultiplexer

We used some existing NI TestStand step types and developed several new ones for different test and measurements. For example, we expanded the function libraries for audio and video measurements as well as digital I/O. Special test steps complemented these step types for functions such as testing the homogeneity of TFT displays, testing IR remotes, or performing mechanical keypad tests. Each test step is parameterized in an interactive configuration window.

Test functions and the configuration window are implemented using NI LabVIEW and/or LabWindows™/CVI software. A customer-specific operator interface complements the software as well as service tools such as the statistical process control or LabVIEW Database Connectivity Toolkit, or the service panel or camera adjustment custom service panels we developed.

Based on the TAVT platform modular and structured concept, the requirements for this special rear seat entertainment test system can be implemented quickly and cost-effectively. Because the concept is scalable, the customer has decided to redesign an existing test system for a different product based on this platform. We developed another similar test system that will test the contacts and problem-free function of displays installed in seats. Six of these test systems are being integrated into the manufacturing system at a U.S. subsidiary of Johnson Controls.

The mark LabWindows is used under a license from Microsoft Corporation. Windows is a registered trademark of Microsoft Corporation in the United States and other countries.

Author Information:
Wilfried Noffz, Certified LabVIEW and NI TestStand Developer
NOFFZ ComputerTechnik
Germany
Tel: 49 2757 99878-0
wilfried.noffz@noffz.com

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