The next three shots tell a different story, however. Parts wobble from side to side, latches shake and the motor base plate flexes as the rotor spins inside.
This hidden world of bad vibrations, containing issues that could require maintenance, was revealed by motion amplification. Designed to exaggerate small movements, the technique works by detecting small variations in pixels from frame to frame, effectively turning each pixel into a vibration sensor.
Patented by University of Louisville spin-out RDI Technologies, motion amplification uses high-speed cameras and specialist software to reveal subtle bends, twists and displacement of components, enabling engineers to carry out preventative maintenance.
The technology was highlighted at IMechE’s Automation of Inspection and Maintenance in Railways event in November last year by Harry Shaw, a mechanical reliability engineer from Cargill. His company is a food and agriculture business, but Shaw set out to show how the video method could be applied “across all maintenance disciplines”, including in the rail industry.
Traditional vibration analysis has long been used to monitor the asset health of rotating equipment, Shaw said, but it relies on single point measurements and requires “significant interpretation”. Operational deflection shapes, meanwhile, allow engineers to visualise entire structures moving, but Shaw said the approach is high-cost and very time-consuming.
“Motion amplification changes the game,” he said. By transforming every pixel of a video into a vibration sensor, the technique provides millions of data points, instead of just a few. The tactile, visual nature of the feedback also offers advantages, he continued.
“By visualising vibrations and movements usually not visible to the human eye, it can really improve stakeholder engagement in a way that raw data and graphs may not be able to,” he said. “By amplifying these small motions, we identify specific faults such as misalignment, imbalance or looseness. This approach helps an accurate diagnosis, reducing repair time and preventing further damage.”
Described as a “superpower” by panel chair Kevin Rayment, reliability process manager at Network Rail, the technology has already been deployed in many industries as a first-line diagnostic tool, working in conjunction with traditional vibration analysis for deeper insights.
The technique could be a “really powerful tool” in rail reliability, forensic engineer Rory Taylor, a consultant at Intertek Capcis, told Professional Engineering. “A lot of the failures that I see are due to something that’s not quite been tightened up… or there’s something that’s not adequately supported,” he said. “There could be a lot of lost time failures prevented just by doing something like this.”
Tribology specialist Taylor, who is also honorary treasurer for IMechE’s Railway Division North Western Centre, explained that vibration can lead to loosening of fasteners and the loss of components from vehicles.
Under the track, meanwhile, ‘soft spots’ of weak, unstable soil can cause excessive deflection, and even derailments in the worst-case scenario. Motion amplification cameras could watch problem areas, Taylor suggested, to see exactly how the tracks move under trains. Proactive maintenance could then reinforce the ground as needed.
Bridges are another potential application, he continued. “One of the main problems with excessive displacement is fatigue of components. If you’ve got some excessive movement on a structural component and it’s seeing a lot of cycles, then it could eventually crack and fail by fatigue. This might be a good way of determining – if you see, maybe, some settlement cracks – if they’re likely to grow, possibly with time, and understand timescales for repairs.”
Taylor’s main background of on-vehicle rotating equipment, such as drivetrains and axle bearings, could also potentially benefit. “Anything that rotates is going to generate some vibration. We can’t get everything perfectly aligned, but there are operational limits. And if you exceed those limits, then that’s when components tend to fail,” he said.
“If there’s something vibrating on the vehicle, it could vary from just a nuisance, something that’s an audible noise as a passenger sat on the train… to something quite serious. So if you’ve got a loose drive shaft, for instance, or a misalignment that’s causing a really uncomfortable vibration… it could be something ranging from a nuisance to catastrophic failure.”
Motion amplification could be a “really powerful tool” for checking alignment of components, he said, either during new builds or train overhauls. Cameras could watch engines or drive shafts during test bed checks, he suggested.
“Usually this is done with sensors. You’ll have some accelerometers on there, and if they exceed a limit, then you have to go fact-finding. But this could be a really good application to hone in exactly where that vibration is occurring and how the thing is moving and behaving in a very simple and visual manner,” said Taylor, who recently presented an IMechE technical lecture entitled The Importance of Tribology on the Railways.
“With normal sensors, accelerometers, if you put them on a vehicle you have to first of all know what you’re interested in looking at. And, second of all, you have to be quite skilled in understanding and analysing that data as well… a lot of time goes into analysing data, so if you can just see it visually, the engineering time and understanding involved could be really greatly reduced.”
However it is applied, Taylor stressed the need for accurate and precise measurements of movement, to enable engineering calculations.
Last year’s event heard that smart inspection and maintenance technologies are already preventing delays and disruption on the UK rail network. Motion amplification could well attract attention as the industry increases deployment of cutting-edge tech.
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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.