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Motion Amplification in Modern Vibration Analysis (Series)

09/23/2021

2021-07-vibration analysis series-part 7This blog post continues an 8-part series on vibration analysis written by Dr. Sara McCaslin & Nolan Crowley, Business Development Manager at HECO.

Dr. Sara McCaslin: Sara has a Ph.D. in mechanical engineering from the University of Texas at Arlington. Sara has also taught materials science, manufacturing, and mechanical system design at the University of Texas at Tyler.

Nolan Crowley: Nolan has BS from Miami University along with extensive field experience with powertrains, electric motors, & vibration issues since 2007.

Motion amplification is a type of video vibration analysis that can reveal the presence of hidden vibration. Often used as part of predictive maintenance (PdM) services, motion amplification can help optimize the reliability of your rotating equipment, including electric motors, fans, pumps, and drivetrains. But what part would it play in modern vibration analysis?

Read on to learn more!

Motion Amplification in a Nutshell

Motion amplification is a non-contact process that turns every pixel in a high-resolution digital video into an extremely accurate sensor for measuring movement and vibration. The data can then be used to generate a new video that amplifies the motion so users can clearly see the components and relationships that are generating the motion.

How Motion Amplification Works

The concept behind motion amplification is fairly straightforward. Basically, the object, system, or structure is filmed while it is running under normal operating conditions. Filming is done by a high-speed digital video camera with an extremely high resolution. It usually takes only a few seconds of video to reveal your powertrain's vibration challenge.

The individual images that make up the frames in the video are analyzed pixel by pixel. How the object moves (displacement and deflection) can be determined by looking at how the pixels are changing between successive frames.

The displacement measurements obtained from the video possess accuracy on the same level as a contacting displacement sensor. That displacement and deflection data can also provide information about velocity and acceleration, as well as vibration for further vibration analysis.

Next, proprietary software algorithms take the data related to position and displacement and scale it up. The scaled movement is applied to the original frames to generate a new video that has amplified the motion so the human eye can recognize it.

The Information Provided by Motion Amplification

Let’s say you know something new is vibrating, but you can’t tell why. A motion amplification scan can help you see where the invisible vibration is occurring. If you look at the video below, you’ll see three different motion scans that make it very obvious what the cause of vibration is.  

 

Three examples of motion amplification videos

In the first video, the pump base is obviously rocking --which tells the maintenance team that they need to better secure that base. The second video reveals that the left side of the base is loose compared to the rest of the structure, again indicating that some minor maintenance is needed. The third video may seem rather extreme but it shows very clearly that something isn’t correctly fastened.

However, videos aren’t the only data that a motion amplification system provides. The data gathered from the original video can be used to extract time waveforms and frequency spectrums, supporting both basic and advanced vibration analysis. That same data, combined with the videos, will help a trained vibration analyst to visualize the math and mechanics of the vibration taking place.

How Does it Differ From Traditional Vibration Analysis Techniques?

Motion amplification approaches problems related to vibration using a very different approach made possible by modern technology and advanced software. It is intended to be used along with traditional vibration analysis, not in place of it.

Motion amplification provides a different perspective, allowing users to more easily investigate how different components are interacting. This can be extremely difficult using traditional vibration analysis techniques, but motion amplification can assist with narrowing down the source and frequencies involved before a full vibration analysis is performed. In short, motion amplification works extremely well with other vibration equipment in order for condition monitoring and troubleshooting.

While a certified analyst can quickly interpret the meaning of spectrum plots and the like, motion amplification videos are more intuitive. The motion amplification videos can be used along with complex data to help others understand the source of a problem and how it needs to be fixed. 

What Place Should Motion Amplification Have in Your Vibration Analysis Program?

Motion amplification is a powerful tool for enhancing PdM and complements traditional vibration analysis rather than replacing it. Some of our customers use it as part of their route-based data collection, implementing it when there are signs of excessive vibration. Motion scans can also be used to check for potential vibration problems when equipment is being commissioned and provide useful baseline data for condition monitoring later. 

As part of your vibration analysis program, it can ....

  • Identify areas of your rotating equipment that experience vibration and deflection
  • Reveal complex interactions at work, including those that aren’t visible to the naked eye
  • Show the effect that different frequencies have on the motion of the system
  • Narrow down the root cause of vibration issues
  • Help identify problems related to misalignment, imbalance, and looseness
  • Detect the presence of potential problems before they start

RDI IRIS-M System

Here at HECO, we use the RDI IRIS-M system, which uses a high-resolution digital video camera that provides 2.3 million video-based sensor points at a sample rate of 180 fps and up to 1,300 fps at a reduced resolution. 

The frequency range is up to 39,000 cycles per minute at 1,300 fps at reduced resolution and down to 5,400 cycles per minute at 180 fps. And it is capable of measuring displacement at  <0.25 μm at 3.3 ft with a  50mm lens and down to 0.125 μm at close focus. The motion amplification factor can reach up to 500x.

Something important to keep in mind with these systems, as with any digital video system, is the importance of light to achieve a clear image and good data. The IRIS-M system comes with an option LED light that provides 23,000 Lux at 1 meter.

Conclusion

Motion amplification is an excellent tool to complement, not replace, your current vibration analysis program. In fact, motion amplification works so effectively it’s part of HECO’s turn-key condition based maintenance offered through our Reliability Services Group. If you’re interested in how motion amplification can increase the reliability of your equipment and complement your vibration analysis measures, give us a call today!

 

 

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