Thursday, December 06, 2007

One Controller Does It All for Machine and Robot

Rockwell has added native support for a variety of robot kinematics to its ControlLogix platform. Other vendors have made similar moves in an effort to eliminate the need for stand-alone robot controllers.

Integrating kinematics into general motion controllers promises to eliminate some stand-alone robot controls


Robots and packaging machines already work together closely – except for their controllers. “OEMs have essentially had to deal with two completely different control systems in the past, one for the machine and another for the robotics,” says Mike Wagner, global business manager for packaging at Rockwell Automation.

Yet, robot and packaging machines may increasingly find themselves sharing a controller. More and more motion control suppliers have started to offer robot kinematics as part of their general motion control platforms, potentially eliminating the need for stand-alone robot controllers and the associated integration headaches.

According to Wagner, the notion of integrated kinematics has always been an attractive one for machine builders and their customers. “Limitations on processing power and intellectual property in the robotics industry kept the controls separate,” he says. Now, though, more powerful processors and the expiration of patents related to Delta-style kinematics has made integrated robot kinematics a likely outcome for many packaging applications. A couple of new examples were on display at the recent Pack Expo show in Las Vegas.

B&R Industrial Automation for the first time in North America demonstrated how its Generic Motion Control (GMC) system can replace a dedicated robotics controller with software that runs on B&R’s controllers.

The software includes a variety of robot kinematics, including a six-axis articulated arm, SCADA and Delta. The demo at the show involved a six-axis articulated arm robot powered by DC motors, but the GMC system has been shown on servo-driven robots as well. “We wanted to show that we could do things other than servo,” says Helmut Kirnstoetter, B&R's international sales manager. In fact, the same GMC software can handle not just AC and DC motors but stepper motors and analog outputs too. Aside from robotics, the GMC system also offers CNC controller functionality and can handle general motion control tasks, including coordinated motion. It supports PLC Open motion control function blocks as well as motion control functions developed in-house by B&R.

Rockwell, meanwhile, showed a more tightly integrated robot control than it has had in years past. As Wagner explains, the company has long been able to offer software that would add some robot control functionality on its ControlLogix platform. Now, though, Rockwell has added native kinematics support to ControlLogix, meaning that the kinematics reside in the controller’s firmware rather than running as function blocks.

“It’s an important difference,” Wagner says, explaining that the native kinematics takes away about 70 percent of the robot-related overhead that would otherwise burden the processor, especially in very fast or multi-robot applications.

Currently, Rockwell’s native kinematics support extends to Cartesian, SCARA and Delta style robots. Wagner says the system can handle basic moves for a six-axis articulated arm robot, though full support for this more complex type of robot is not available yet.

B&R and Rockwell are certainly not alone in the push toward integrated robot control. At the previous Pack Expo, Bosch Rexroth demonstrated its take on the technology.


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