Motion control: The past 10 years

By Loren Shaum, Contributing Editor

Over the past 10 years, there have been significant advances in machine automation. Progress in vision technology, for example, comes to mind as, perhaps, the most innovative of all the automation technologies over that time.

Contributing to any perceived lag in motion innovation is the consolidation in the industry over the past 10 years. Consolidation has reduced the number of innovative, entrepreneur-style companies to a very few. This leaves machine builders a bit more vulnerable to a more-limited choice of brand solutions, rather than a best-of-breed solution. Hence, for many machine types, the void in competitive solutions has resulted in a higher cost per axis on each machine.

Regardless, motion has made some significant advances during Control Design’s 10 years. There’s no room here to expand on all of them, but some of the more prominent might include:

• Transition from analog to digital drives
• Higher efficiency in power stage devices
• Faster, cheaper microprocessors and DSPs
• More distributed drive solutions via fieldbus advances
• Integrated power amps with motors
• Alternative, smart feedback devices
• Innovative drive algorithm developments, allowing one drive to handle any motor
• Drives with more I/O, and I/O with motion capability
• Universal selection software allowing any motor/drive combination to be considered for almost any mechanism configuration
• Emergence of real-time Ethernet-wrapped protocols

What’s clear is that many more machines are being built today using electronic, servo control, replacing line-shaft, pneumatic and/or hydraulic solutions.

One of Control Design’s earliest editions, February ’98, took a shot at identifying emerging trends in machine controls. Conspicuous by its absence among the eight trends was any real mention of drive technology. However, the article saw something coming. In its “What About These?” sidebar, it noted that “Integrated drives, the combination of controller and motor as one unit, are becoming popular where variable-speed functionality has to fit in small spaces. For open-loop vector control, the miniaturization of inverter components and new feedback algorithms are bringing small-footprint drives up to 10 hp into practical use.” It clearly didn’t stop there.

All of us were accustomed to finding a rectifier diode, power transistor, thyristor, gate-turnoff thyristor (GTO), and the insulated gate bipolar transistor (IGBT) in electronic drive technology descriptions. However, in the June 1998 issue, we examined a technology that “claims to be the world’s smallest, standard medium-voltage AC drive system—in terms of power and voltage compared to size—is now on the market. The compact size is achieved by using an integrated gate commutated thyristor (IGCT) semiconductor switch. The IGCT consists of a power-handling device known as a gate commutated thyristor (GCT) integrated with the device control circuitry. Uniform switching eliminates the need for a snubber.” We reported claims that IGCTs deliver extremely fast switching and high yields suitable for power conversion from 400-6,500 hp at up to 4.16 kV. IGCT technology, developed by ABB Industrial Systems was touted to operate at up to 1,000 Hz, which was four times faster than previous power devices at full rating.

Electric Power and Efficiency
In the June 2001 issue, we got a sense of what electric drives and motors were becoming capable of when we reported on Milacron’s all-electric injection molding machine, which the company claimed to be two to four times more energy-efficient than conventional machines and could save 8.9 million MWh of electricity.

“Some of the largest global companies have already mandated across-the-board energy reductions in their operations because they realize the cost savings go straight to the bottom line,” said Barr Klaus, vice president of technology for Ferromatik Milacron North America. “At three times the efficiency of conventional machines, all-electric injection-molding technology can be a strong component in those reductions, and our resource center will serve as an important, time-saving means to accelerate validation of the process.”

Though it sounded contradictory, “all-electric injection molding machines actually are three times more efficient than conventional hydraulic machines,” claimed Klaus. “That’s because the all-electric machine motors use energy only when actually doing work, unlike conventional hydraulically powered machines, where motors consume energy while idling.” A switch to new all-electric injection machines was expected to save an estimated 700,000 MW of power and $42 million in energy annually in California.

With all the emphasis on drive electronics, Control Design didn’t forget about motors. A September 2001 Editor’s Page aimed at those machine builders who relied on big motors and drives with heavy-duty cycles, argued they could do their customers a big favor by encouraging use of motors meeting high-efficiency standards.

Earlier that summer, CEE, a consortium of motor manufacturers, trade associations, electric utilities, and government agencies, kicked off the “Motor Decisions Matter” campaign to encourage more motor management to cut energy costs.