9/15/1999 | 9 MINUTE READ

Robotic Quartet: Digital & Real

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Among some of the newer products being offered by robot companies are software-based systems, which shouldn't be too surprising nowadays. Of course, work beyond manipulating digital information still needs to get accomplished, so there is also new iron...


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Time-to-Volume Facilitator

"Adept's dirty fingernails and SILMA's virtual reality" is the way that Joe Campbell, VP of Marketing at Adept Technology (San Jose, CA), describes Production PILOT, a 3D, CAD-based assembly process planning and design software suite that Adept is launching.

What Campbell means is that Adept, which has shipped more than 15,000 robot systems, knows plenty about what occurs on the factory floor (thus, dirty fingernails), and that SILMA, which Adept acquired in 1995, has spent a number of years developing advanced-but-usable 3D factory-floor simulation tools (e.g., its package for the creation and verification of programs for coordinate measuring machines, CimStation Inspection, has been selected for use by Ford Motor; the program with the automaker is valued at some $15-million).

Production PILOT
Creating a line with a suite of simulation tools like Production PILOT from Adept facilitates process optimization so that when the real thing gets installed, ramp-up time is minimized.

The objective of Production PILOT is to accelerate the implementation of automation on the factory floor by allowing users to get a better handle on what will meet their needs before any automation is put in place—or even purchased, for that matter.

Campbell points out that while people often stress the competitive advantage of fast time to market, Adept people are emphasizing the ability to achieve fast production ramps, or what is called "time-to-volume." "Volume," he notes, "is what gets you market share."

To be sure, there are a number of simulation packages available from several sources (for line flow analysis and optimization, feasibility assessment, yield prediction, and cycle time prediction). One of the key benefits that Production PILOT has is that, according to Campbell, it comes in at a cost that is 75% less than what would need to be spent for less well-integrated software (it uses a single environment and database). A seat of Production PILOT is approximately $50,000.

There are three levels of the package: PILOT Line, PILOT Cell, and PILOT Yield. Input for what is to be built comes from CAD files; there are direct interfaces with many of the major CAD vendors' systems, as well as 3D neutral interfaces (e.g., IGES, STEP). Process information is Adept-neutral: certainly, there is abundant data related to the specs of Adept robots and peripherals, but there are lots of other vendors' equipment well represented (robotic and otherwise).

PILOT Line is for discrete event simulation: the first cut at laying out cells and balancing the lines. What's more, there are financials included in PILOT Line, to permit determination of investment and operating expenses, as well as possible savings.

PILOT Cell goes deeper: here actual cell designs are devised; the virtual workcell permits cycle time prediction. Users can perform a variety of what-if scenarios (as in, "What if we change the length of the roller conveyor?" or "What if we add another robot to the line?") in order to determine process feasibility. This goes all the way to physics-based simulation, taking into account things like the fact that real parts can bounce, which can cause assembly problems (which is certainly an example of dirty-fingernail understanding).

As PILOT Cell is about process feasibility, PILOT Yield is about the product: digital mock-up and tolerance stack. In addition to allowing the simulation of the assembly of a component and the determination of such things as whether parts actually have sufficient clearance to mate, PILOT Yield even permits the generation of GANTT charts to track the process.

Throughout all of these packages, the user is working with a single interface, so there is a seamlessness from Line to Cell to Yield.

(On the hardware side of things, Adept is also bringing out what are called SmartModules. Essentially, this is a compact unit that includes a amplifier with power electronics, encoder interface, and servo control digital signal processor. The SmartModules employ FireWire, a high-performance serial bus that was developed by Apple Computer [there is actually now a standard, IEEE 1394, and plenty of vendors are offering products so one shouldn't worry about the Apple association in this increasingly Microsoft-centric world]. This provides high rates of data transfer, simple plug-in between the backplane and devices, and a thin serial cable connector. One result is that the individual motor power cables and encoder feedback cables—which turn into multiples pretty quickly for a multi-axis robot—are replaced by FireWire such that there is a 65% reduction in the number of cables used. Which means there are improved reliability and reduced costs, in addition to the overall reduction in size. Adept is rolling SmartModule technology throughout its Cartesian and SCARA robot line.)

Surfing the Factory Floor

ABB believes that Internet access to robots on the production floor will help increase uptime.

The ability to monitor production data via the Internet? This, according to Jim Winfree, product manager, ABB Flexible Automation, is a unique capability that ABB is offering (at least unique with regard to robot vendors), one that facilitates production management of robots on the factory floor. By simply utilizing the familiar Microsoft Internet Explorer browser—from office, home, shop floor, wherever—diagnostic, timing, counting, and other information can be readily accessed in a simple-to-understand format via the ABB WebWare system. (To be sure, there is security built in, so not just anyone can log on to your factory floor and check out what's going on.)

Essentially, there is a server. And there is the WebWare Software Development Kit that allows the creation of PC-based (as in off-the-shelf PCs) operator stations on the factory floor. These stations can be setup to have human-machine interfaces (HMIs) like those available from companies including WonderWare and GE Fanuc. These stations communicate with the ABB robot controls on the factory floor, and, in turn, with the server.

One of the benefits of this setup is that there can be scheduled saves of the robot programs running on the factory floor so that there is always an up-to-date file of what is being used. (Recognize that there are sometimes floor-initiated program adjustments that aren't appropriately filed; this takes care of that.) What's more, by having good remote diagnostic information, technicians can quickly get to the source of problems and keep the robot uptime high.

At present, the WebWare package communicates only with ABB S4 and S4C robot controllers. A single server can handle any number of controllers, but it is recommended that if there are more than 30 robots, then in order to be more efficient in collecting data and routing network traffic, more than one factory-floor PC be used to facilitate flow.

The system employs Microsoft OPC (OLE for Process Control). According to Winfree, this open protocol is used instead of DDE, an older protocol. He's found that an increasing number of manufacturers are making the same OPC selection. Consequently, he says that ABB is developing a generic OPC client interface for WebWare that will allow connection to other plant floor devices using OPC, most likely PLCs.

One of the things that users can't do with WebWare—with good reason—is to make modifications to programs from a remote location. The reason: robots are about motion. And safety is key. "It requires someone on site to load programs back into the control for safety reasons: we can't allow a remote user to cause motion," Winfree says. He adds, "The same thing is true of I/O signals. Technically, they could cause motion."

Being able to have ready access to what the factory automation is doing—or not doing—is certainly a key benefit to those who are looking to optimize uptime, which is what automation must have if it is to provide return on investment. Fundamentally, this is what WebWare is all about.

Nachi SG160P
Note the robot at the bottom: the Nachi SG160P. By having a compact design yet significant reach and payload capacity, it allows weld lines in body shops to be significantly shortened.

Addressing the Final Frontier

Space is always a consideration in assembly line construction. According to Michael J. Bomya, vice president of Engineering at Nachi Robotic Systems (Novi, MI), there is now the opportunity to notably shorten the length of the line in the body shop because they've developed a new line of robots, the SG Series. And by notably, he means half the length of a normal weld station, because the SG160R and SG160P are both compact units, yet they provide long reach and heavy payload capacity necessary for wielding spot welding guns. In terms of height, the SG160R is just 1,250 mm; the SG160P is a mere 921.64 mm. The forward reach of the former is 1,100 mm. The overall reach (fore and aft) envelope for the SG160P is 2038.9 mm. Both have a capability of handling 185 kg (160 kg at the wrist; 25 kg at the forearm).

What all of this means in practice is that there can be a highly dense layout of robots within a weld cell, either configuring it with just SG series robots or combining them with Nachi's other more conventionally configured models (e.g., setup a line so that the SG160P can work on the lower portion of the vehicle while an SA160F reaches over to the juncture of the body side and the roof).

Nachi has also developed a servo gun for spot welding which provides several advantages compared to typical air guns—not the least of which is a much quieter weld environment (75 dB rather than 85 dB). The servo gun allows thetips to be smoothly brought into place and pressure applied, which not only eliminates distortion of the surfaces to be mated, but also reduces burring and spattering by half, while helping improve the life of electrodes by 30 to 50%. In addition to which, because there is less impact force, the support structure for the assembly station can be lighter.

The servo gun can be programmed so that there is synchronization between it and the movement of the robot, thereby helping reduce the overall cycle time.

An important aspect of the servo gun is that electrode wear is automatically measured, so worn electrodes can be changed before they cause any trouble.

Standard for the Press Room

Motoman Inc. (West Carrollton, OH) has been concentrating a great deal of its engineering know-how in developing robotic packages that allow the company to offer packages to customers that don't require a whole lot of engineering. In other words, rather than having special-engineered robotic systems (which means there is a cost associated with the engineering part of the jobs), it is offering packaged robotic systems to perform specific functions for which the engineering is minimal at most.

One of the latest packages that should be of interest to metal stampers at suppliers and OEMs alike is PressWorld. This system employs the SK16 robot, a six-degree-of-freedom unit that provides a reach of 61.22 in. and the ability to handle 35.2 lb. Additionally, there are a controller and menu-driven application software, integrated gripper package (mechanical or vacuum grippers can be utilized), integration with a press, an electrical interface for press-to-robot signals, and safety guarding.

Advantages that robots can provide for material handling in press operations is, according to Motoman, reliability and flexibility.

Bill DeCamp, Motoman's director of Marketing, admits that much of the work that PressWorld can do is being done with dedicated equipment. "But robot costs are coming down and they can be reapplied to jobs more easily," he notes. As for the first point, PressWorld packages can be obtained for less than $100,000; depending on the complexity of the jobs to be performed, the prices go north.

As for the second point—the flexibility—this is fairly clear: a robot is fundamentally flexible and dedicated automation is, well, dedicated. "Stamping companies are looking for quick changeover time," DeCamp says, "and fitted with quick-change tooling, the robot can do the job."

But some people think that there is an inverse relationship between flexibility and reliability as in the more flexible a piece of equipment is, the less reliable it will be. "Some dedicated equipment—such as special loaders—are often less reliable than robots. We've got a proven design and thousands of units in the field—the risk is taken out of it," DeCamp argues. A special loader may be one-of-a-kind. According to Motoman data, the SK16 robot has a mean time between failure (MTBF) greater than 50,000 hours.


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