Robots The Next Generation

For years if you told someone that you work with "industrial robots" they'd hear the "robots" part and think about something like something from Forbidden Planet or The Day the Earth Stood Still. Yet the robots you're talking about look more like something built with an Erector set. Motoman's new industrial robot looks, well, like a "robot"-yes, the humanoid kind.

If you think about it, the industrial robot, despite the fact that it historically hasn't looked at all like a human, has always been anthropomorphized, either in terms of application-as in doing the jobs ordinarily done in factories by people like welding and machine tending-or as in the description of the elements of the device-waist, arm, wrist. Of course, unlike the robots of popular culture, industrial robots have had little similarity to people. But Motoman (www.motoman.com; West Carrolton, OH) is changing that. Its dual-arm robots-the DA20, the DIA10, and the SDA10-are true industrial robots, yet they have an overall configuration that has distinct humanoid qualities.

Craig Jennings, Motoman's president and COO, explains that the work on these dual-arm robots began with work being done on actuator-based robots. That is, rather than using typical robotic mechanical architecture that deploys motors driving shafts, the compact actuators (that combine the motor, encoder, reducer, and brake) can be stacked. The result of the use of the actuators for arms means there is a slim profile, that Jennings describes as being "a near shape to a human arm." So this led to a seven-axis robot, the IA20, that has a 44.1-lb payload, a 44.88-in. reach from the centerline of base rotation to the tool mounting surface) yet when straightened vertically requires only 1 ft2 of floor space. Jennings points out that with conventional robot design, the number of axes has a direct effect on the overall size of the robot, because as the number of axes increases, so does the size of the motor because it has to deal with drive mechanisms that are not in line. The stacked actuators eliminates that problem. He does acknowledge, however, that there are limitations to how much mass the actuator design can accommodate; he sees it going to 50 kg and "eventually 80 kg." But he has an implementation strategy for industrial operations that could make that suitable for some applications like spot welding that otherwise utilize much larger robots. That is, because the latest version of the IA10, the SIA10, is so compact, it is possible to put more of them in a welding cell than would be possible with conventional robots. Add to that the ability to snake into places within a body-in-white, then Jennings says that the need for deep-throated spot welding guns that are being frequently used to be able to handle various models on a line can give way to smaller guns on these robots. There is the additional benefit of reducing the size of the cell because of the small footprints of the robots. 

In addition to creating a slim robot, Motoman's engineers have been working for some years on control technology. Not only have efforts been made to simplify programming and operations, but also to allow a single control to operate more than one robot at the same time. The latest control is its NX100, which has the ability to simultaneously handle 32 axes.

So, combining what the compact servomotor brings with the robust controller capability, they developed the DA20, a dual-arm robot that has 13 axes of motion: six per arm and a base, or waist, rotation. The DA20 can handle 44.1 lb. per arm, and each arm has a reach of 30.1 in. from the centerline of the base to the tool mounting surface. The arms can work independently or in coordination: One arm can hold a part and the other can perform a process on it. Jennings says that while the DA20 provided notable capabilities, "The six-axis version of an arm doesn't give humanoid abilities. You need seven axes for humanoid tasks." So they developed the DIA10, which has two seven-axis arms and a waist, for a total of 15 axes.

Now, moving beyond even that-and realize that the DA20 was introduced at the International Manufacturing Technology Show in September '06-Motoman is coming out with the SDA10, which is even more human-like, inasmuch as it is a slimmed down version of the DIA10 (it has the same weight capacity). Jennings explains that the design objective for the SDA10 is to put it directly in applications where people might work, women in particular. Jennings says that if you go to manufacturing operations, particularly in the low-wage countries, you'll see women standing shoulder-to-shoulder, performing tasks. Jennings says that rather than sending these tasks offshore-where there are risks associated with the pirating of intellectual property, long supply chains, and other negatives-the work can continue to be done cost-effectively by the dual-arm robots.

Jennings thinks that Motoman will sell approximately 10,000 robots of this type by 2015, of which 40% will be in automotive applications (another 40% will be in electronics). In the realm of automotive applications he says that they see great potential in the body shop, such as placing doors, fenders, hoods, and decklids on bodies. Trim and final operations have long been places where there hasn't been much robotic incursion; Jennings says that the two-arm robot has applicability there. In addition, there are tasks in powertrain, like transmission assembly, that can be accomplished. There is also the facility to add vision and force-feedback sensing, which makes these devices even more capable.

He acknowledges that the dual-arm robot is more expensive than a conventional robot. But the price is proportional to that of two traditional robots with an addition of approximately $10,000 to $15,000 for the S-axis. But he suggests, "The dual arm opens up a plethora of applications that can't be done economically with single-arm robots. What's so elegant is that as soon as you go multi-arm and working in concert, the tooling and the environment become simpler-you dramatically simplify the tooling and the infeed and outfeed of production." Speaking of the tooling, for example, he says, "Less sophisticated gripper technology can accomplish what we did with an 8-sxis customized manipulator."