With its dual emphasis on precision and cost effectiveness, electronic motion control has moved from being a bit player to a major force in industry. Today, it is critical technology in machine tools, packaging, and robotics. Tomorrow, say its advocates, it will be just as critical in a wide range of other industries, particularly those that require speed and efficiency on the factory floor.
To find out what the major breakthroughs are likely to be in electronic motion control as we approach a new century, Design News talked to several suppliers and users. You'll read their assessments in the next few pages, as well as one industry leader's views on tomorrow's motion-control systems.
The controller stands alone
Ease of use has become a defining characteristic of electronic motion control. Engineers at Galil Motion Control expect that to continue being the case well into the next century, with most of the growth of the technology occurring in less sophisticated markets. "When we started introducing products that plugged into a PC, we began to see ordinary electrical engineers as customers, physicists as customers, and technicians as customers," says Jacob Tal, president of the Sunnyvale, CA, company.
There exist two different philosophies concerning PC-based motion controllers. One is to rely on the PC to perform a portion of the processing. The other--the one preferred by Galil and competitor Delta Tau Data Systems (Northridge, CA)--is to make the motion controller so smart that it can stand alone. The link to the PC is for communication, not processing. "We really do this because it is easier to diagnose if something goes wrong, not because it is inherently more powerful," Tal says.
Today, Galil's new third-generation controllers take ease of use--and capability and performance--one notch higher. The product line consists of three devices, the DMC-1000, DMC-1300, and DMC-1500. Each is identical in capability, but the 1000 plugs into a PC, the 1300 targets VME-bus machines, and the 1500 is a stand-alone controller.
While the company may be touting ease-of-use, these third-generation controllers aren't slouches. All offer control of one to eight axes, including step motor, servo, or hydraulics. A 32-bit microprocessor and a custom sub-micron gate array give them four times the speed of their predecessors. Encoder feedback can be as high as 8 MHz, sample rates may be as short as 125aesec, and RS232/RS422 communication reaches 38.4K baud. And in the case of the DMC-1500, it's half the size and 40% cheaper than the previous generation DMC-700.
Modes of motion include the usual jogging, linear and circular interpolation, and contouring. It also includes electronic gearing--the ability to synthetically gear up to eight axes with variable ratios between them--and electronic camming--the synchronization of up to seven axes with a master axis to simulate the motion of a mechanical cam.
One company that agrees with Galil's vision of motion control is Glasstech (Perrysburg, OH). The firm's line of glass bending and tempering systems operate in 50 countries on six continents and are responsible for producing 80% of the 3-mm-thick glass sidelites used in all the world's automobiles. Each of four different bending and/or annealing machines depends on two 3-axis Galil controllers. They command the servo motors that power the glass-feed conveyors and run the gear trains that control a flexible bed for shaping the glass.
"We really don't do any sophisticated motion," says Dene Rinaldo, Glasstech's senior control engineer. "We chose Galil because the cards are reliable and the programming language, while sophisticated, is easy to use."
With his products spread across the globe, Rinaldo needs to be able to troubleshoot easily over the phone. He finds that Galil's line-interpretative language can be understood by most any engineer familiar with BASIC. Program printouts can be reviewed remotely on the phone, or modifications can be sent via Compuserve's e-mail. "To spend $3,000 to fly someone halfway around the world to make a one-line change in a program is not what we want to spend time doing," he says.
"Twenty years ago when you shipped a system, you shipped an engineer with it," says Tal. "Now it's more important to have comprehensive diagnostics built in than any other function."
Reliability is also important to Glasstech, and Rinaldo has been impressed with the durability of Galil controllers. "Our machines run seven days a week, three shifts a day in a very warm environment," he says. "Our customers don't need Star Wars; they need something that is easy to use and runs for years."
Programming skills? You won't need them anymore
Traditionally, installing, programming, and debugging a motion control system has been as much black magic as engineering. Designers at Berkeley Process Control say their new MachineWorks(TM) machine controller can eliminate the hocus-pocus and greatly speed the development of motion control systems, while also increasing reliability. "It's a breakthrough in the utility of machine control," explains Steve Kraft, product development manager, "not in raw performance, but utility."
The MachineWorks concept is basic: simplify through pre-integration. Since most machine development involves integrating hardware and software, Kraft and a team of engineers at Berkeley designed MachineWorks to eliminate these steps using something they call direct machine development.(TM)
Direct machine development simplifies the traditional development process--plugging in cards, connecting possibly incompatible components, and especially, writing lines of code--by providing an organizing structure for machine control built into the system. Developers can enter complete machine-control sequences from a touchscreen, following menu prompts, without any conventional programming.
The development process involves a series of on-screen prompts and selections. A full machine database, Quickstart(TM), gives users access via the touchscreen to servo functionality, axes, I/O naming, auto-tuning, etc. All underlying issues--the black magic--of axes setup, error handling, diagnostics, and hardware configuration are anticipated.
The step-by-step process combines pre-written building blocks of optimized code into the complete debugged system. Complex operations are separated into tasks, entered via the touchscreen, and can then be executed simultaneously for true multi-tasking.
The crucial benefit is time to market. "We've done jobs that have traditionally taken six weeks, and with MachineWorks, we've done them in two or three days," says Kraft. The Apple Computer of the motion-control world, Berkeley designs all its components to work together. They are specifically machine-control components, and they integrate quickly and easily, Kraft says. And programming, the part of the job where days can slip to weeks and months, is reduced to the assembly of optimized, pre-compiled instructions via MachineWorks.
An example of MachineWorks in action appears at Meadows Manufacturing (Sunnyvale, CA). The company's problem: how to retrofit a two-year-old, four-axis product insertion machine with the least downtime and the largest increase in reliability. Engineers also wanted to convert the machine from semi-automatic to fully automatic operation.
Pedro de la Serna, project engineer at Meadows, describes the machine as an X-Y-Z table that holds a nest of pre-measured portions of a liquid product. The table repositions each portion in front of an insertion actuator that pushes the portion into individual product applicators.
The new control system consists of Berkeley Integris, which includes MachineWorks, multi-axis amplifiers, I/O system, interface, power supply, and an enclosure. As a fully integrated solution, the turn-key operation was up and running quickly--with greatly increased capability and reliability.
The largest time savings occurred in programming. With MachineWorks, the insertion machine's software was written and debugged in two days. "We took the product down to their facility on Monday and left on Wednesday with a fully functional machine--full diagnostics, everything," says Kraft. And he left the system, with complete confidence, in the hands of de la Serna, a mechanical engineer who had never seen a Berkeley Process Control product before.
Kraft stresses that his company's solution is not inflexible. With Meadows, for example, engineers defined two custom sequences using MachineWorks' Extensions option.
Only a few months into the new system, De la Serna already plans to expand the machine's capabilities. Kraft isn't surprised. "Instead of focusing on technology, performance, and numbers, we're focusing on utility," he says. "If you can't use it, it doesn't matter what the raw capability is."
Flexibility is the driver
To see where motion-control is heading, one need only look at changes in the office-automation market, says Scott Hibbard, vice president of Indramat, Wood Dale, IL. The transition from centralized mainframe computing to minicomputers to distributed, open-system PCs foreshadows developments in industrial control.
If you want to gauge the industry's progress on that path, the best place to look is the machine-tool market. "In the metal-cutting industry, multi-axis machining centers are replacing dedicated transfer lines," he explains. "But greater flexibility can't mean sacrificing production rates or machining accuracy." The technological answers to the needs of these most-demanding applications will, in Hibbard's words, "bleed down into other industries."
Indramat's latest, the DKR digital ac servo drive, highlights what's coming. Microprocessor technology makes the drive a common platform for controlling motors from fractional to 100 hp. "One drive, one software package for rotary permanent magnet, rotary induction, linear permanent magnet, and linear induction motors," recounts Hibbard. It includes electronic gearbox and cam functions, function monitoring, and real-time machine-or-drive diagnostics to simplify troubleshooting tasks and boost machine uptime.
In addition to simplifying system setup, smarter drives mean easier development work for controls manufacturers. Where different applications required different motors and thus, different drive platforms, now software developed for one application is instantly available to all. There's more functionality, and it's more widely available.
The DKR drive also includes the fiber-optic, open SERCOS communications interface. SERCOS not only reduces wiring complexity, it's a high-speed link that will enable the lowest-level distributed control that is changing the motion-control industry.
Where most people think of distributed control as PLCs or motion-control cards operating one or several motors on a machine-by-machine basis, the new model, says Hibbard, is smart drives linked by SERCOS and communicating with a much-less-harried master controller. "Any control function performed on an axis-by-axis basis is a candidate for placment in the drive itself."
There's no longer the need to control a position loop or do fast offset corrections upstream in a centralized controller, Hibbard contends. Thus, as machine controllers have less axis-control work to do, they become candidates for open architectures like PCs. "We're taking away the peculiarities of the CNC or PLC," he says.
The shift to distributed control governed by PCs will mean much less reliance on system integrators for machine programming. A user will be able to purchase packages of software and put together his or her own control system if that's their wish.
For controls makers, the shift will make success a little harder to achieve. Yet Hibbard is optimistic about the future. "There will always be advantages to choosing one piece of hardware over another," he says. "As long as your company is technology-driven, you can still stay on top of the game."
Users: Write your own interface
The advantages of higher performance that come with advances in motion-control hardware design are lost if running the new systems becomes too complicated. That's the message from Cosmo Mirra, general motion-control product manager at GE Fanuc. The opportunity exists for the "popularizaton" of high-performance electronic motion control, he says, but only for those who don't forget the users.
The core challenge facing controls makers comes from the proliferation of controller hosts available today--CNCs, PLCs, and PCs. Large industrial users of motion control, such as the auto industry, adopt the new control technologies as a requirement of staying competitive. But adding new systems alongside previous generations of controls creates problems. "They run a number of different processes and they want a common operator interface from machine to machine in order to control their training costs," explains Mirra.
Traditionally, controls manufacturers took one of two approaches to operator interfaces (OIs), continues Jeff Kao, a GE Fanuc applications engineer: Either an industry-standard look and feel as with CNC commands, or a totally open approach where users design their own screens.
For old customers like the machine-tool industry where CNC originated, a standard interface often suffices. Large industries, like automotive, usually have or can afford the programming expertise necessary to construct custom interfaces. But to expand electronic motion control into new territories, the company felt it needed a different approach to building OIs.
As part of its recently introduced PowerMotion line of high-precision, distributed-control products, GE Fanuc introduced the C Executor, a development tool that greatly simplifies creation of custom OIs.
"We compile our programs on an IBM PC using Microsoft C," explains Kao. "You load the program in, get up and running quickly, then customize the presentation of data to meet the user's needs."
For example, says Kao, a robotic painting system can be configured to go to location 1, 2, or 3 instead of the operator calling CNC coordinate codes.
One user has already seen the benefits gained from an easily customizable interface. James Rodrigues, product manager for the robotics division of Husky Injection Molding Systems, Bolton, Ontario, says PowerMotion with C-Executor could be the key to winning new customers.
Husky developed a three-axis gantry robot for materials handling to serve its molding equipment. It needed a teaching pendant to enable users to operate the system, but shied away from non-intuitive languages that customers didn't know.
"We needed to have application software that was specific to injection molding to properly market the product," explains Rodrigues. With an assist from GE Fanuc applications engineers, C Executor allowed Husky to develop a menu-driven front end that incorporates industry terminology. "We think people will like it because they can relate to it and learn it quickly." He continues, "If we had to use off-the-shelf software, customers would probably shop elsewhere."
As Mirra sums it up: "With the C-Executor, we're marrying a high-performance motion system, a descendant of complex multi-axis CNC, with an easy-to-use software tool." That's how you make motion control popular.