Economical motion control: low dollars and good sense

Interest in the class of single-axis motion controllers for continuous motion is growing, thanks to the technology's ease-of-use and quick payback.

Design News: How do you define economical motion control?

Slye: To me, economical motion control is a system that meets the user's needs and pays for itself in a short amount of time. So the fact that one of our units costs $900, for example, does not make it economical in and of itself. The improvement in production processes that it delivers also helps to achieve a quick return-on-investment.

The factors that contribute to a short payback period can be very subtle. For example, we have special units for wire machine operators that allow them to enter their setpoints and variables in units that make sense to them. In this way, they can directly set and very precisely maintain something like slip percentage to a significantly lower value, which they could not do in the past for fear of snapping the wire.

Q: How has demand changed for economical motion control?

A: Since the mid-1980s when the company was started, we've seen unit volume grow every year. I think one of the reasons engineers are moving to this technology is that they want to be producing good products right from the beginning of the process. Without motor control, operators will be tweaking things back and forth for the first 10% of the run. Likewise, they have to scrap the product produced at the end of the run when the machine is slowing down to a stop.

Another reason is that factories everywhere used to have a staff of production engineers, electricians, or somebody who really understood how the production machines and processes worked and knew how to fix problems. But a lot of those people retired or were laid off and never rehired. Since many factories today cannot depend on knowledgeable people to oversee these processes, they work with com- panies like ours that can help them control the process.

And, finally, as ac and dc drives become smarter, the line between our controllers and other more expensive offerings on the market is blurring. We're competing against servo in a wider variety of applications.

Q: What is the biggest challenge associated with marketing an economical controller, when the servo mindset is frequently that the most ex- pensive solution is the best?

A: I think there is initial skepticism on the part of some potential users-they aren't sure that they can get the performance they need out of a controller that is a fifth the cost of other controllers. So the hardest challenge is simply getting them to try it out. The way we've overcome that hurdle, though, is by being successful in the marketplace and by solving more and more applications out there. It's much easier when you can tell a customer that he isn't the first one to apply a technology in a particular way.

Q: What do design engineers need to know in order to make the best choice in motion control for their application?

A: They need to know what size motors they plan to use and how many axes they need to be control, and whether the motion required is continuous or point-to-point. They need to know what kind of investment they are prepared to make-if any-in programming and learning to use a new system. They also need to ask themselves how much operator interaction they want and how the machine is going to be maintained.

Q: Can you give us a preview of some of the technology developments in the works?

A: To give you kind of a historical perspective, our product has gotten more diverse over the years. On our new MS 232, we will be having panel-mountable units with multiple axes built right in. We will also have applications built directly into our controls. In fact, we've already done control for weaving machine, tension control, traverses, winding and unwinding, electronic gear boxes, index registration, and other applications. Controllers of the future will be even easier to use and customers will be able to order a particular controller by function, which more closely matches the thought process when specifying a controller.