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Among the simplest and least expensive feedback devices are Hall-effect sensors.  These are digital on-off devices that detect the presence of magnetic fields.  Made of semiconductor material, they are rugged, can be operated at very high frequencies (equating to tens of thousands of motor rpm), and are commonly used to provide six-step commutation of brushless motors.

Most machine builders are familiar with modern touch screen HMI's. They have all but replaced older style toggle switch panels. It has also enabled machine builders give operators much more information on the process going on in a machine. HMI's can look at a multitude of machine variables and they can be presented in a more relatable graphical format than digital readout or analog meters. For instance, instead of a tank volume number, you visually show the operator much fluid is in the tank. HMI's however can go even beyond these operator related touch-screen graphics. Some of the more sophisticated features can really benefit machine builders and end-users of machines. Here are a few capabilities you might not have known about modern HMI's.

There are a number of situations that call for crossing over and replacing an existing motor with a newer servo. These can include: product obsolescence, cost savings, lead time issues, or upgrading to newer technology. The specifics of each application could lead to an endless number of important factors to consider. In this post I will try to (briefly) identify those that are most common and their correct order of concern.
In our previous post of this series, we learned that the selection of a feedback device is critical for precise motion applications, and that where it's located is important as well. Today's post covers some additional information regarding the difference between absolute and incremental feedback and why should I care, as well as a few other considerations.

As soon as you walk into a quiet space, you know it. In the world of automation, noise tends to be considered a necessary byproduct. A number of my colleagues have become very adept at describing the various noises made by stepper motors, leadscrews, cams, gearboxes, etc. Wheeeeeew. Wheeeeeeeeeeew. Wheeeeeeeeew, clack. This tends to be fine if you're talking about a single axis of motion, but imagine a hospital lab with hundreds or perhaps thousands of axes of motion all moving at the same time. Try having a quiet conversation in a large lab around the 8:00am sample rush - just about impossible.

A critical element of any servo system is the feedback device - after all, that's what makes it a servo to begin with! How about a very simple example to start off with: I have a bow and arrow, a target 30 feet away, and I left my glasses at home. So while I do see a large round "thing" in the distance, I have trouble making out the edges of the rings on the target. My feedback is not very accurate at the moment - so I'm likely not going to hit the bull's-eye. I discover my glasses in my pocket, slip them on - and now I can see the target much better, and I at least have a better chance now of hitting the target. Yes, there are other factors, environmental, arrow construction, etc., but you get the point (pun intended)!
There aren't many of us that open up the hefty manual that you receive with your new lawn tractor or dishwasher but if you did there would be a section in there on "preventative maintenance." There's a similar section in the documentation that comes along with most IVD analyzers and other lab equipment. The documentation often includes recommended activities to be done on a weekly, monthly and yearly basis to keep your instrument running as intended.
Machine builders focus on functionality and reliability when first designing a new machine. Ideas are put on paper and components are strung together in block diagrams with thin lines to show the association of all the pieces. It is the most creative time in the cycle. Things can be moved and shifted with ease because everything is on a whiteboard. Even if you are far enough in the cycle to work in a CAD model, changes require no physical effort and the task of putting it together is still just an idea.
Although my blog entries will generally call attention to new ideas we think will end up someday on the factory floor, drive-by-wire actually lags industry: this type of following, such as electronic gearing (a.k.a. cam profiling or camming), has been available in Industrial Automation for years.
Coating and lamination applications demand precise speed regulation in order to avoid velocity ripple that causes uneven coating and undesirable horizontal bars across the substrate. The key to achieving the most uniform coating is minimizing the variations in velocity as well as in metering of the coating material.


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