A matter of control

A matter of control

Universal controller expands research capabilities at Oak Ridge National Laboratory.

Universal controller expands research capabilities at Oak Ridge National Laboratory.

The Universal Robot Controller lets shops with multiple robots train users on only one type controller, saving both time and expense.

The high-intensity plasma-arc lamps used in Oak Ridge National Lab's experiments instantly melt tungsten, making precise motion control vital to research.

The URC lets users at Oak Ridge National Labs change research parameters in minutes rather than hours.


Oak Ridge National Laboratory in Oak Ridge, Tenn., is known for cranking out new manufacturing technologies that help industry leap forward in its journey toward cost-effective and scientifically advanced production. But to effectively discover and test these new technologies, Oakridge researchers often have to turn back to the manufacturing industry for help in updating the lab's own systems. In the most recent case, the lab turned to Robotic Workspace Technologies Inc. (RWT), Fort Meyers, Fla., to purchase a Universal Robot Controller (URC), which is helping the lab use high-intensity plasma-arc lamps to treat, temper, and form corrosion-resistant coatings on materials.

The new system replaces a tape-drive control on a Cincinnati 776 robot. The robot had sufficient brawn for the job at hand, but the brains needed some updating. The lack of speed and flexibility of the old controller was holding back progress on the plasma-arc-lamp research.

"From a mechanical standpoint, everything about that arm was extremely solid," says head project researcher Dr. Craig Blue. "The controller, however, was essentially useless."

In the plasma-arc-research project, Blue passes a plasma-arc lamp, with 3.5 kW/cm 2 of power over the surface of a material. The heat is enough to instantly melt tungsten, so moving the lamps at a specific speed and at a set distance is crucial to the experiment.

The new URC uses RobotScript, a macro-like robot programming language, employing Microsoft's ActiveX technology and based on VisualBasic. This lets users create programs in a range of environments including Microsoft VisualBasic, Visual C++, or even Microsoft Office. RobotScript runs on a Windows NT platform when used with the URC but works off-line on any PC running Windows NT/95.

The programming language's suite of tools has four parts: the RobotScript ActiveX Control, the URC RobotScript Control Screen, the Teachpoint File Creator, and the Microsoft Script Debugger. Each of these has a specific function. The Teachpoint File Creator, for example provides programmers a graphical method to teach point locations for a RobotScript program. Wizards help users teach complex processes, like motion-coordinated output. A graphical display makes it easy to visualize, verify, and edit point locations. In addition, the file creator can be used off-line to create RobotScript text files. These files are then converted into robot-motion programs by the RobotScript ActiveX engine. Since no binary data files are used, programs don't have to be compiled before being run.

The Control Screen provides a user interface that lets programmers run RobotScript programs. An optional soft-ware-development kit lets the end user write a custom control screen that reflects application-specific parameters. In addition, users of the kit can also implement a standard company-wide interface.

Testing and debugging of RobotScript programs is completed through the Microsoft Script Debugger, which lets programmers step through a RobotScript program as well as display the program's logic as it is being executed.

RWT configured the URC for the Oak Ridge robot and shipped it with the part programs already prepared. After only three hours of installation and setup, the robot was running in production mode.

When installing the URC, the old controller was simply disconnected and the URC connected in its place.

"If we do all our homework before we install it, meaning we make sure we have the program written correctly, the cable connections are right, and the power is at hand when we get there, the client can easily be up and running in less than a day," says RWT president Walter Weisel. "If it's going to be a really complex installation, you do it over a weekend."

The controller was tested by moving the lamp to treat flat-stock, powder-metal parts, and it provided speeds and accuracies previously impossible.

"What the URC did was save me lots of money. For me to go out and buy a brand new arm, with a brand new controller — without knowing how user-friendly that controller would be — could get us into the 6-figure area," explains Blue. "By putting the URC and its Microsoft-based software system on it, I now have a valuable arm."

The URC gave Blue the consistency needed for the experiments and cost-effective versatility. "Basically, we can change things on-the-fly. That is the crux of why I wanted the RobotScript software and URC," says Blue. "I probably have 10 different programs for the lamp right now. Upon completion of one experiment, we can immediately change the parameters in the URC. If in the next experiment we're going to change the scan speed, it takes less than a minute. In the old days, we'd have to walk around this huge tape-drive controller hoping it didn't go down. It took a fair amount of time."

Since robot time at the lab is charged at $150 to $160/hr, the faster a change can be made, the better. "If I have guys fumbling with archaic controllers — even where it would only take two or three hours — to me, that's $500," Blue explains. "If they can change over in RobotScript in only two minutes, I've saved $500. This is the type of thing that hits the bottom line."

Increased safety was another benefit of the URC. As a PC-based system with standard inputs and outputs, it allowed Oak Ridge to put in optical sensors, door sensors, or proximity sensors that instantaneously shut down the arm if there is a safety concern. The controller also opened doors for expansion at Oak Ridge. The design of the URC lets it be easily updated at a small cost. By changing a board in the processor, the controller becomes virtually brand new, and an upgrade package allows users to download new programs for their URCs over the phone or through the Internet.

New life for old robots

When it comes to robots, the brain, or controller, usually dies before the body. There are two reasons for this. One is that robot manufacturers have proprietary programming languages for their products. As new-generation models are introduced, these languages change, and programs written in later versions of a language usually aren't compatible with earlier versions and vice-versa. As such, controllers tend to become obsolete about every four years, while well-maintained robots can go 50,000 hours, or 12.5 years, between major overhauls. Unfortunately, few OEMS offer controller upgrades for their existing robots. The result is an arm capable of handling tasks far beyond its controller's ability.

Another reason controllers become obsolete is improving scan rates. Robots use feedback loops to control motion. In a feedback loop, a signal tells the arm to move to a specified position. The arm then signals back, telling the controller its actual position, and the controller makes any necessary adjustments. The rate at which this occurs is the scan rate. The faster the scan rate, the more precise the motion control. The current URC has a scan rate of approximately 2,300 times/sec.

A URC is also of benefit to those shops with multiple makes and models of robots. Since the controller is truly universal, it can be connected on all makes of robots, letting shops train employees to use and maintain one controller instead of several.

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