Automatic Temperature Measurement with Precise Infrared Pyrometers

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"Using LabVIEW and advanced programming, we met the customer’s measurement requirements with a short delivery time and with cost-effective reusable hardware and software. "

- Zoltán Ványi, Head of Software Engineering, ENG Systems Hungary Kft.

The Challenge:
Developing an automated test solution to replace an existing manually operated system, and increasing the system’s measurement precision and system reliability.

The Solution:
Using NI X Series DAQ multifunction I/O devices and LabVIEW software to deliver a quick solution for measuring different analogue and digitally programmable pyrometers, and creating reports using the LabVIEW Report Generation Toolkit.

Author(s):
Zoltán Ványi, Head of Software Engineering - ENG Systems Hungary Kft.

ENG Systems, a small, but dynamically expanding limited company, works on industrial measurement and control solutions. As an NI Alliance Partner, we use LabVIEW, TestStand software, PXI systems, reconfigurable I/O (RIO) architecture, CompactDAQ hardware, and X Series hardware. Our customers include automotive suppliers, domestic manufacturing companies, and international manufacturing companies.

For this project we worked with our customer Atlas Copco—Industrial Technique Hungary Kft., an industry-leading pneumatic tool vendor with products ranging from pneumatic motors to handheld instruments. A number of the company’s products are certified as ATEX safety tools, which means the tool cannot cause a fire or explosion. The device temperature has to be kept under control.

Our goal is to record and display temperature for up to four channels per unit under test (UUT). The units are turned on and run continuously at a nominal pressure. Depending on product size, the test period can vary between a few seconds to a couple of minutes.

Background for Specification

In another cooperative project, ENG Systems is also developing a comprehensive TestStand-based multistation test system for several physical measurements for all Atlas Copco products. When that test system launches it will integrate this Temperature Measurement Station.

NI Design Advantages 

The X Series DAQ product line provides enough channels both for measuring signals and handling digital I/O lines within one device at an outstanding benefit-cost ratio. USB connections are the easiest way to connect measuring architecture. The X Series USB devices feature a rugged aluminum case, which protects it against mechanical shocks or electrical noises. We can use DAQ hardware for the whole integrated test system and as a universal device that fits all test requirements. Whether measuring speed, resonance, air pressure or consumption, or power or weight measurement, we can cover all tasks with the same X Series DAQ device. This includes both channel amount and measuring speed (maximum angular speed to be measured is going up to 110k RPM). Thus, the Temperature Measurement Station and all the next TestStand applications can run on the same hardware boxes, which results in a highly flexible solution with low development costs.

Quick, Reusable, Rescalable Solution

NI emphasizes advanced programming techniques and offers trainings on various topics such as software development strategies and managing complex projects. We can use this knowledge very efficiently to design measurement solutions with fully configurable, scalable, modular, and reusable code. We can implement the measuring modules into the TestStand structures launching in the future. We only need to define test structures, SQL databases, and control clusters for test modules. Based on these definitions, we can create a universal code module for the Temperature Measurement Task (see on Figure 1), which will fit into the TestStand architecture. Until then, instead of TestStand, a LabVIEW VI acts as a framework and executes this code module. Control parameters come from XML parameter files since there is no SQL database background yet. The framework also manages report generation. We created two types of report printing. The customer required we use a third-party freeware PDF creator application, which works by template. It is easy to use but not convenient for graphs. The main advantage is that the customer does not need to install MS Office for report generation. The LabVIEW Report Generation Toolkit is the other option with well supported options for graphs and creating easy-to-read reports in color. The customer can configure which solution generates the report.

How the Measurement System Works

Products are categorized first by product family and second by specific test parameters. A parameter group contains XML files for Limits, Drives, Instruments, TestSpec, and ParameterSet clusters. These have exactly the same structure as the clusters in TestStand that will configure the test modules.

 

Figure 1. Software Front Panel Initial Screen—Graphic Shows Theoretical Limits

The test application registers maximum temperatures of different parts of the products, over the ambient temperatures. Measuring temperature on the house of the UUT is simple. We chose the high-class IPE-140 pyrometer to measure on spinning, small, and shiny shafts. Configuring this ‘camera’ using serial communication, that is for setting emissivity factor for different surfaces, and reading the measurement signal on the analogue inputs (4–20 mA) is the same as with the Calex pyrometers.

Practically, the heat of on the operating product will be stable state for a while. The program records charts, finds the stabilized maximum levels, and calculates differences from ambient temperatures. Depending on authority of the logged-in operator, the program can be more or less flexible to adjust a test, allow overheating, and more.

Hardware, Fixture

Figure 2 shows a smart computer with a dual-core Intel Atom CPU next to the DAQ device. This compact, fanless embedded computer is strong enough for LabVIEW or TestStand deployments and saves space and power. We use only signal conditioning boxes for 4–20 mA current loops to DAQ Analog Inputs and a signal driver for DAQ Digital Outputs lines to 24 V DC power range.

Figure 2. Hardware Implementation With Embedded PC and the NI-USB 6341 DAQ Device

The fixture for UUTs is also a quick and provisional solution until the final integration for global test structures launches. It is designed by ENG with the main goals of being simple to use and fast to develop. The shaft-sensing pyrometer is mounted to a ball joint positioning system to reach all expected positions in different products. We mounted other meters in a fixed direction, but these also can be lifted up or down and shifted vertically. The fourth sensor measures the ambient temperature. The fixture can also hold two different seats for the UUT and a multipositioned lift with two fixing arms (see Figure 3). This fixture can hold up to 25 products and different sizes or shapes.

Figure 3. The Fixture With Small, Medium, and Large UUTs

Summary

Using LabVIEW and advanced programming, we met the customer’s measurement requirements with a short delivery time and with cost-effective reusable hardware and software. Atlas Copco—Industrial Technique Hungary Kft. started the Temperature Measurement Task much earlier than they launched their overall test system.

Author Information:
Zoltán Ványi, Head of Software Engineering
ENG Systems Hungary Kft.
Tel: +36 1 2406383
vanyi.zoltan@eng.hu

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