Industrial Machine Design: Leap of Faith?

Technology trends don't always lead to better machine design, but CONTROL DESIGN's Senior Technical Editor Dan Hebert found a few that could help you break away from the crowd.

By Dan Hebert

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August 2004, cover imageWe all sometimes think of ourselves as independent, "I gotta be me" captains of industry. But the direction of business is constantly affected by external market trends, some inevitable and overwhelming, others subtle and infectious, but all emerging to shape change. Sometimes this influence happens whether we like it or not. Sometimes, it's when we're smart enough to catch on early and ride a wave of disruptive technology.

 

What follows is our forward-looking view of machine builder industry trends. In it we look at how advances in automation, instrumentation, and electrical technology are likely to affect you and the direction of business. Some of the trends we cover are the direct result of vendors addressing OEM needs, while others are external influences that must be addressed by OEMs.

Some of the trends we identify probably are no great surprise to any of you. Others might be accelerating into the market faster than you think. Regardless, they all are having significant influence on the way our industry strives to improve machine performance, reliability and versatility

While there's bound to be disagreement when selecting a short list of mighty technology trends, in our minds, these are the ones likely to make the biggest impact:

  • Integrated hybrid control platforms,
  • Real-time machine vision,
  • Global standards,
  • Wireless network infrastructure,
  • Distributed machine control,
  • Machine safety, and
  • Servo motor/drive deployment.

Many Functions, One Platform
Machine functionality often includes a need for discrete, analog and motion control capabilities. Until recently, this meant integrating multiple controllers. Hybrid controllers now are available that can perform all needed control functions with one integrated platform.

Hybrid controllers are capable of at least two of these types of control: discrete (on/off), analog (process), and motion. Hybrid controllers are not special-purpose controllers, because the latter can only perform one type of control. Typical special-purpose controllers are small PLCs (discrete), single or multiloop PID controllers (analog), and motion-only controllers.

At this point in market evolution, virtually every PLC vendor offers hybrid controllers capable of discrete, analog, and motion control. Most loop-control vendors offer products that also can perform discrete control, but motion control is not addressed within this product class. Motion controllers that perform discrete and motion control are now common, and it's possible to find motion controllers with analog process control capability.Given the state of today's market, controller selection now is driven by specific application characteristics rather than device characteristics.

One of the main applications for hybrid controllers is motion control coupled with discrete and/or analog control. Two main types of products compete in this market space: motion controllers with discrete and analog I/O plus logic, and PLCs with motion control capabilities.

R.A. Jones Inc., best known for its line of high-volume packaging machines, has been performing a complete range of turnkey design and integration services for more than 25 years. The company uses hybrid motion controllers because "hybrid control streamlines the control architecture by removing the logic needed for handshaking between the motion controller and the discrete controller PLC," says Darren Elliott, chief engineer of Jones' electrical controls group. "This means less logic, quicker scan times, less hardware and less wiring. Reliability is better because there are fewer points of failure, and startups are quicker because there is less debug time and because hybrid controllers are easier to troubleshoot. It is also simpler to integrate advanced, time-critical functions such as registration when motion and I/O information are controlled uniformly into one central processor."

Because many industrial OEMs associate PLCs with discrete control only, new terminology is being used to describe hybrid controllers. "We see a trend towards the convergence of control disciplines into a single, multi-discipline controller," observes Rick Morse, manager of strategic applications for Rockwell Automation.

The Vision to Control
Machine builders and customers have long supplied and used automated vision systems for off-line inspection. Lately, the use of vision inputs for real-time control is gathering steam as an industry trend.

Several technology advances are acting simultaneously to improve vision system performance in real-time control applications. A smart camera not only is faster, smaller, and cheaper than its dumb cousin; it also is easier to interface to real-time controllers. As with hybrid controllers, more vendors are making control of functions such as motion and vision an integral part of their control systems.

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