The continued push to improve manufacturing productivity and slash expenses is prompting robot makers to make major changes, shrinking control modules in order to save space on the factory floor. Increasing capabilities of processors and a focus on power electronics are keys in this change.
The control module has been completely eliminated by Adept Technology Inc. of Livermore, CA (www.adept.com). Its Cobra line integrates this module into the robot itself. "There's a 40% reduction in cost, and we eliminate the space used for the control box without adding extra space onto the robot," says John Dulchinos, Adept's sales vice president. Pricing also falls below the $20,000 barrier.
Also minimizing controller size, West Carrollton, OH-based Motoman Inc. (www.motoman.com) recently unveiled the first robot that uses a single controller for four separate arms, managing 36 axes with one control module.
Adept is addressing the broad market for individual robots, though its products are designed for easy interconnection with other manufacturers devices. The company altered its architecture for new products a while back, using 1394 FireWire to link modules together. Rather than putting boards and modules on a bus, the modules and robots are tied together with 1394, a scheme developed for consumer products. This technique also makes it possible to replace large cable harnesses with thin 1394 cabling. As engineers combine robots with vision, I/O, communications, and other links, the 400 Mbits/second link can be used in daisy chain fashion or fanned out from hubs.
While 1394 is important, integrating the controller into the robot is even more significant, Dulchinos says.
Shrinking required far more than just using smaller microprocessors. The Cobra line handles a 12-lb payload, so power requirements are fairly high. "Power is the biggest piece of the size reduction, it's where our biggest effort was," says Brian R. Carlisle, Adept CEO.
One aspect of dealing with power was shrinking the power amps to a size that could be squeezed inside the robot. The power module went "from the size of a hardcover dictionary to the size of a stapler," specifically a 2 x 6 inch module that supports one high power axis of motion, Carlisle explains. Also, a single DSP chip now controls multiple power amps, saving space over the previous 1:1 relationship between amps and DSPs.
In addition, the developers turned to large FPGAs, with over a million gates, to handle encoders. That saved a fair amount of board space. "A single FPGA can handle six absolute encoders," Carlisle says.
The Cobra line also aims at simplified operation. The robots can be programmed by PCs or PLCs.