NI-Based High-Speed Wood Panel Testing System

Author(s):
Rob Taylor - LightWave Computing Tech. Ltd.

Industry:
Basic Materials - Steel/ Lumber/ Construction

Products:
Compact FieldPoint, LabVIEW, Profibus, FieldPoint

The Challenge:
Building a high reliability online tester for plywood and OSB panels with complex I/O requirements.

The Solution:
Using LabVIEW and National Instruments FieldPoint, PROFIBUS and DAQ products to build a sophisticated test system.

CAE Machinery, a major manufacturer of wood product processing equipment, needed a control system for their PanelMSR online tester of wood-based panels, and we, at LightWave Computing Tech., designed a system to meet their needs. Our machine measures panel-bending properties, such as stiffness and modulus of elasticity (MOE) of plywood and OSB panels up to 4 by 12 ft long. The system provides real-time feedback to the mill, so the user can adjust production to provide improved product consistency. This ultimately pays off in lower production costs and higher product yields.

Determining Stiffness and MOE
In order to bend panels of different thickness enough to determine their stiffness and MOE, we had to control nine panel-bending servo drive motors, as well as three conveyor drives. We also needed to maintain data acquisition rates high enough to properly represent panel stiffness profile, signal other equipment to sort panel quality, and interlock the online tester with other mill equipment. The servo drives set the degree of bending applied in two stages inside the machine. While the DAQ board handles background buffering of the data using direct memory access (DMA), the CPU is free to perform filtering and analysis functions, giving the system time to gather results before the panel exits the machine.

Processing Signals
We needed a system that could process required load, temperature, thickness, and photocell data quickly, so we chose a National Instruments E Series DAQ board, along with a SC-2345 signal conditioning chassis, which was ideal for our low-channel count requirements. As the panels pass through various stages, the machine analyzes buffered analog input data from the DAQ board online to determine the strength of the panel. With the ability of the DAQ board to provide background buffering using direct memory access (DMA), the CPU performs filtering and analysis functions, giving the system plenty of time to gather data before the panel exits the machine.

FieldPoint Modules Track Speed
We used two National Instruments FieldPoint distributed I/O nodes to handle the drive motors and general machine interlocks. Because of the compact size and industrial design of FieldPoint, we could locate our I/O close to the machine, greatly reducing wiring complexity and cost. We used the new FieldPoint quadrature encoder input module, FP-QUAD-510, to track the conveyor speed while the relay and isolated digital input modules controlled the interlocks for drive motors and mill conveyor systems.

Improved Reliability
Our software development benefited greatly from the ability of LabVIEW to spin off tasks, and we easily performed online acquisition, filtering, and analysis of data. All machine control is performed through one VI on a local PC that has all the attached I/O hardware. In order to monitor and control the application, both locally and remotely, we chose DataSocket, a technology for sharing data access networks. Using DataSocket, we easily communicated with the machine control VI from two separate remote stations over an Ethernet network. Because we use NI DataSocket technology to simplify data exchange, we improved the modularity and reliability of the system.

Conclusion
With our NI-based tester, we successfully perform tests on OSB and plywood panels at the impressive rate of one panel per second. The system performs to the same degree of precision as much more labor-intensive stationary test stations; and because we put together these diverse control requirements using a single vendor, NI, we avoided the issues of driver incompatibility that plague multivendor solutions.

For more information, contact:

Rob Taylor

LightWave Computing

111 Regina Street

New Westminster, BC, Canada, V3L-1S4

Tel: (604) 522-1786

Fax: (604) 522-1726

E-mail: rob.taylor@lightwavecomputing.com

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