The Power of Video Vibration: Non-Contact Sensor
By Chad Pasho
Using video as a sensor has unique benefits for measuring vibration. Chief among these benefits is no longer requiring contact with the target object to be measured. Typical vibration measurement using an accelerometer requires mechanical contact with the object, transferring the mechanical motion of the object to the sensor, which then translates this into a signal describing the original motion.
In many circumstances this is an acceptable limitation. However, for the remaining situations, we may have become accustomed to making do without vibration data. If the equipment or piping is too hot, too high, or otherwise too hard to access, we spend significant time and/or money getting the necessary data, or forego it altogether.
|MSI's Maki Onari getting ready to take vibration data on a gas turbine|
For hot equipment or piping, there are accelerometers rated for high temperatures, but in practice, we have found these to be a) very expensive, and b) limited in longevity. And that’s just the sensor. Sensors typically don’t affix themselves to the equipment or piping being measured! Putting our people into this environment is a risk we do not take lightly. Heat exhaustion and burns for our most important assets (our people) are serious matters, and we’re always looking for ways to mitigate that risk while still getting the quality data we need to solve our customers’ problems.
Similar in terms of risk and associated expense, it is sometimes “not worth it” to get measurements on overhead piping or equipment. Erecting and inspecting (and waiting for) scaffolding, dealing with personnel lifts, making sure personnel have appropriate training and fall protection gear, along with the general risk of things, or sadly people, returning to the ground in an uncontrolled manner, make the cost/benefit analysis often come down in favor of doing without that vibration data.
While heat and height are probably the most common problems, there are a variety of other situations that make getting vibration data difficult. High radiation or explosive environments, difficult to access areas, or anything that puts personnel at increased risk is an unwelcomed complication to getting data. And, one of my personal favorites is “protected equipment”, or that equipment which is so vital to operational happiness that it shall not be touched or even approached (but they would still like to know what’s wrong with it). Thankfully, you’re still allowed to look at it, which means you’re back in business with video vibration!
As long as you can see the object for which you would like to measure vibration, you can use video vibration to get the data you need. Bearing the relationship between field of view (how much area you are looking at with the camera) and displacement detection threshold in mind (see related blog on displacement), you can safely position your camera where you need to, and use the appropriate lens to get the field of view you need. No longer do you need to ask how hot is it, how high is it, or is it hard to get to. The question is merely, “Can I see it?”
We’ve built VibVue™ from the ground up to accurately measure AND quickly magnify vibration at incredibly low levels of displacement, including at high frequencies. And it’s why we continue to experiment with and apply unique ways to leverage video as a non-contacting sensor.