Motion System Design

Keep the application foremost

Digital technology is phenominal, but let’s remember it controls an analog world

As consumers, we are told that the newest and best cell phone technology is digital, that digital audio recordings are far superior to analog methods, and so on. Even the U.S. Congress is getting into the act by considering legislation that would mandate digital television by the year 2007. That move would obsolete all TVs in the home today, but our new digital viewing experience might threaten to make couch potatoes of even the most resistant consumers.

In industry, the control of machine motion has evolved — in just a few short years — from mechanical systems to analog electronics and now to digital electronics. High-performance motion control systems no longer employ only digital position loops, but have evlolved to include digital velocity loops and now even digital current (or torque) loops. The interface between controls and drives has migrated from the traditional analog signals to digital control over fiber-optics.

Digital technology provides suberb benefits, no doubt about it. However, one critical truth is quite often overlooked — we still live in an analog world! Whether talking about cell phones or television, metalcutting or printing machinery, designers must always address one critical decision — at which point shall the digital-to-analog conversion be made? The answer continually shifts as technology advances.

Design engineers and applications experts too often lose sight of the fact that an analog world still sits at the end of all these nifty high-tech digital electronics. As technology advances exponentially, the sheer volume of information which must be absorbed makes it easy for engineers to become specialized into a sort of “digital tunnel vision.” Yet, these digital experts are the ones who must manipulate, control, and ultimately tame this analog world. From the fly-by-wire control of today’s aircraft to the sophisticated stability control systems now appearing in automobiles, to automated baggage handling equipment, the end task is to control a world that moves continuously in an analog fashion. The better our engineers understand this analog world, the more controllable it will be.

In these digital times, the difference between a good engineer and a great engineer frequently boils down to the degree to which he or she can effectively translate digital advantages into the analog world.

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