Motion Control Resources
Universal Drives Simplify Integration
by Kristin Lewotsky, Contributing Editor
Motion Control & Motor Association Posted 09/24/2007
Drives that can operate with multiple motors minimize inventory, enhance system flexibility, and make motion control more accessible.
If you want to do motion control, you need, among other things, a motor, whether brushless AC, brushed, permanent magnet, single-phase, three phase, or what have you. And where there is a motor, there must be a drive. Put yourself in the shoes of a motor manufacturer or machine builder: not only do you have to carry an inventory of three to five types of motors, you also need to carry three to five types of drives.
Or do you? Buoyed by sophisticated digital signal processors (DSPs) and microprocessors, drive manufacturers have begun developing universal drives that can run multiple different types of motors. The process has been enabled in part by an overall trend toward modularity in motor design. “Even 10 years ago, different hardware was the norm because the components selected were rather different, as was the architecture itself,” says Karl Meier, marketing manager at Advanced Motion Controls (Camarillo, California). “It dictated separate drives, whereas today, you’ve got similar architecture with similar components leading to similar drives.”
Essentially, it all comes down to the software and the firmware. “The technology behind the microprocessors and the DSPs that are used allows additional capabilities to be included,” says Meier. “As long as there is an ability to operate multiple algorithms for the different motor technologies on a common drive platform, then indeed they can and will be the same.”
Of course, motion control systems are built by engineers and if there’s one thing an engineer knows it’s that in trying to do everything, you run the risk of doing nothing well. The perception can also be that in paying for a universal drive, the user is buying capabilities they don’t need. Neither are accurate. The performance of the universal drives is just as good as motor-specific drives and a multi-platform technology can pay off big time when it comes to integration. Users and machine builders only have to learn one common software package and companies can minimize the number of products they need to carry in inventory.
“Does it make motion control overall more usable? Absolutely,” says Meier. “A common drive platform allows a potential machine builder or user to learn only one package. [If] they select a different motor technology, perhaps tune a loop or reconfigure settings, they don’t have to relearn an entirely new package. They just have to do a few things a little differently.”
Perhaps even more important, the platform offers engineers the freedom to test out more than one motor on a specific axis to choose the best solution. A team could start out using a three-phase stepper in a certain application but find that it provides insufficient speed or torque and they must turn to another solution. “Machine builders can upgrade the motor without having to change their drive and without having to change their control,” Meier says. That is important because keeping the same controller saves time and money.
Sometimes, even swapping out motor types can provide cost savings, in both real costs and in terms of simplifying sourcing and support. “They could start out with a servo and realize they can do the application with an ac induction motor with some closed-loop feedback, which saves them money,” Meier says. “[A common platform] reduces their overall supplier base. If they choose to do so, instead of relying on external technical experts, [they can] become the technology expert.” They can do all this without having to spend a large amount of time looking at new suppliers, which can be time-consuming and costly in and of itself.
Making the Most of Motion Control
“As we continue to move forward, it’s very important to provide products that are higher performance but easier to work with,” says John McLaughlin, manager, North America for Elmo Motion Control (Westford, Massachusetts). “Again, that’s the challenge: to simplify the use of digital drive products as much as possible.” In the digital era, fewer engineers are graduating with focuses in motion control. For cases in which engineers don’t have broad expertise, the simplifications offered by a universal drive might be just the right solution.
As with all technologies, it’s important to understand the application thoroughly to make the right motion control choice. “The universal drive is no panacea,” Meier cautions. “There’s no one size that fits all, does all. The universal drive concept is more to try to capture the system builders, integrators and OEMs who are looking for multiple technologies to be solved from a common platform, whereas some OEMs are building specific machinery that have details not lending themselves to a universal drive at all.”
In the end, it comes down to picking the right system for the job. “I think a customer having the option to select his own motor to meet his application needs and the right drive is the best approach to take,” McLaughlin says.