Add vision to robots — see the difference

Robots Paired With Machine Vision Create Automated and Efficient Motion, Leaving the Old Generation Behind

By Dan Hebert, PE, Senior Technical Editor

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How Hard Is It?
Adding vision to a robot isn't always easy. "There are challenges with the seamless integration of sophisticated vision, robotics and the accompanying automation systems," Wicks says. "This advanced level of integration requires a collaborative effort on the part of the vision systems providers, robotic arm manufacturers and robotic systems integrators because it requires in-depth knowledge of not only the vision piece, but also how it integrates with the robot and other automation equipment."

Fung says that most vision systems must be designed specifically to meet the requirements of the tool into which they are to be incorporated. "This increases the overall tool cost as well as the design time," he explains. "There's a lack of generic, industrial-quality vision systems that can be programmed easily to meet a variety of system requirements. Most vision systems are difficult and complex to operate. Much of the system complexity is due to the high image quality required for most applications, as well as challenges involved in accurately measuring parts that don't conform to regular shapes."

Software and lighting pose problems, too. "We've seen advances in both software and lighting for vision systems, but there are many opportunities for further improvement," CMD's White says. "While the software has become increasingly user-friendly, end users still need some proficiency with programming and setting up the cameras when they introduce a new product. Depending on the type of features the customer is looking for, this can be a tedious process of adjusting the camera and lighting to show the intended features. Products have different patterns, colors, sheens and materials that can complicate setup."

Fung agrees and suggests improvements. "Lighting systems must be able to fit into the tool without adding excessively to tool size," he says. "Designers usually have to use very thin, industrial-grade backlighting, which is expensive and further increases overall system cost. Filtering to prevent stray light reflection is also a concern."

Most robot and vision vendors recognize the integration challenges and provide solutions. For example, White explains how Yamaha software helps, saying, "The software program in the Yamaha RCX controller is a modified form of BASIC. The commands are actually quite simple. For instance, a MOVEP command (move to position) tells the robot to move to a given X,Y,Z coordinate. The Yamaha firmware and hardware determine the most efficient path and control all the motors to arrive at the destination as smoothly as possible and within the defined limits."

Steve Zhu, director of business development for Teledyne Dalsa, describes a system the company built at a Honda plant that also uses vendor software to advantage. "Our GEVA1000 vision system and Sherlock software is being used for China's Dongfeng Honda Assembly line, where an ABB robotic gripper is used to grip the car body accurately and reliably (Figure 2). Our GEVA1000 with Sherlock guides the giant ABB robot to locate the car body properly."

Sherlock software tells the robot where to go. "With its search tool, the software can recognize marks and locate the right positions where the grippers should be put on car bodies of different sizes," Zhu says.

HMI software vendors also provide assistance with robots and vision. "The volume of data produced by vision systems operating at high speed can't be handled by most database servers, and specialized data historians may be required just to capture the data stream," says Fabio Terezinho, vice president of consulting services at InduSoft. "The OEM's vision system uses our HMI capabilities to show and ameliorate volumes of complex, high-speed data, especially in a quality assurance (QA) application where parts are inspected by the high-speed vision system at 10 msec intervals."

Some of the integration problems can be eliminated by using a robot with a vision system supplied by the robot manufacturer (Figure 3). "We use Fanuc robots with their integrated iRVision, so we no longer purchase many third-party vision systems, says Tom Spisak, senior controls engineer at integrator Automated Cells & Equipment, Painted Post, N.Y. "Before iRVision, we purchased Cognex cameras and integrated them into the robot cells." Why the change? "Faster integration and easier support from a single manufacturer, which translates into lower costs and increased performance," Spisak says.

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