Monitoring Arc Welding Applications at ABB

Author(s):
Jörgen Lundberg - Midroc Electro AB
Anila Jonas Uller - Midroc Electro AB

Industry:
Industrial Controls/ Devices/ Systems

Products:
PXI/CompactPCI, LabVIEW

The Challenge:
Building a system to monitor robotic arc welding applications used in research, development and production.

The Solution:
Using a PXI and SCXI combination system with CAN and DAQ hardware, signal conditioning, and LabVIEW.

Improved Welding System Performance

ABB is a world leader in robotic arc welding with robot applications in more than 40 countries. ABB Automation Technology Products AB, Business Area Unit Arc Welding and Application Equipment, based in Laxå, Sweden, develops, markets, and supplies products, systems, and software for robotized arc welding, thermal cutting, and robot peripherals. The welding products and systems range from compact, standardized robot cells for simpler tasks to large, customized solutions.

We developed a measurement system, WeldMAN, to monitor the arc welding process. WeldMAN acquires data from analog and digital sensors as well as communication information from the CAN buses within the welding system. Typical analog signals are voltage, current, and gas flows. We use WeldMAN in two major ways:

• As a process surveillance tool for monitoring current, voltage, and electrode speed during the welding
• As a diagnostics tool for synchronizing the CAN messages in the control system with the analog data

 

High Analog Acquisition Rates

We designed the system to synchronize CAN and DAQ data with an acquisition rate of 10 KHz. We selected the PXI-1010, a combined PXI and SCXI chassis, as the hardware platform. We used a PXI-6602 counter/timer board for synchronizing CAN and DAQ signals. The counter/timer board routes one clock signal to the CAN board where the clock signal is time stamped using the NI-CAN RTSI timestamp capabilities. We route another clock signal to the DAQ board and use it as the acquisition clock. With this solution, we achieve high analog acquisition rates while maintaining CAN performance.

Configuration System for Individual Settings

We developed the software using graphical object-oriented programming (GOOP) in combination with traditional LabVIEW dataflow programming. The system uses an XML-based configuration system for individual settings. Each system user has a profile which controls data acquisition methods and data analysis capabilities. The program has three major parts, including configuration, data acquisition, and data analysis.

Configuration

The user configures a data acquisition method that describes the CAN messages and analog channels to acquire, the acquisition speed for the analog channels, and the start and stop conditions. The start and stop conditions include a software pushbutton, analog trigger, and CAN message trigger. The triggering is softwarecontrolled so the user can have the same triggering settings for start and stop. Digital triggering is also possible but not required at the current state.

With the WeldMAN configuration interface, you can select CAN messages and DAQ signals to acquire start and stop measurements using CAN messages and/or analog levels.

High-Speed Data Acquisition

The data acquisition focuses on performance, and the user is only informed about the acquisition status. Data is stored in binary files using a tailor-made data storage package optimized for high acquisition rates and large file sizes.

Specialized Data Analysis

We developed a data analysis package to meet the specific needs of this application.With the package you can perform visual examination of CAN and DAQ data, as well as calculation and export functions. The analysis package communicates with external analysis tools giving the user the ability to add new analysis capabilities without any programming. This feature can also distribute calculations across the network.

Data is analyzed graphically, so the file is automatically split into data intervals to improve performance and make it possible to analyze large amounts of data.

Result

Our solution for an arc welding process monitoring and diagnostics system was to create a measurement system based on PXI and SCXI technology. The system uses a combined PXI and SCXI chassis running Windows NT 4.0, a PXI-6040E board for analog data, and a PXI-8461 board for CAN data. A PXI-6602 counter/timer board handles the synchronization of CAN and DAQ data. We used an SCXI-1125 module for analog input and an SCXI-1126 module for frequency-channel input.

We designed the software using LabVIEW and the GOOP toolkit, which is available as a free download from National Instruments. Using the GOOP toolkit, we achieved a higher degree of code reuse and application expansion because the toolkit enforces modularity in your LabVIEW code, which is a good programming practice to follow. For large applications, using the GOOP toolkit to produce more modular code means that each VI contains simpler code. Simpler code reduces costs due to reduced development times and increased productivity. Also, because the code is more modular, it is easier for more users to work on the project at the same time.

Today we use WeldMAN on multiple hardware platforms for in-house development, as well as trouble-shooting at customer sites. The simple yet powerful user interface makes it an effective tool for users ranging from research and development to manufacturing test.

For more information, contact: 

Midroc Electro AB

Jonas Uller / Jörgen Lundberg

Lagergrens gata 4

652 26 KARLSTAD

Tel: 054-13 05 50

E-mail: info.iel@midroc.se

 

 

 

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