Tag Archives: vibrations

Driver sleeping.

Your car’s vibrations are making you a lousier driver — by lulling you to sleep

Just 15 minutes in a car makes us sleepier, affecting our ability to drive. After 30 minutes, this effect has a “significant impact on your ability to stay concentrated and alert,” researchers warn.

Driver sleeping.

Image via Pexels.

According to a new paper published by researchers from RMIT University in Melbourne, Australia, cars themselves may be a significant threat against our ability to drive safely — some 20% of fatal car accidents today involve driver fatigue, they explain, and, according to their research, the vibrations we experience in cars makes us sleepier, posing a major risk for motorists everywhere.

Snooze cruise

“We know 1 in 5 Australians have fallen asleep at the wheel and we know that drowsy driving is a significant issue for road safety,” said Professor Stephen Robinson, paper co-author. “When you’re tired, it doesn’t take much to start nodding off and we’ve found that the gentle vibrations made by car seats as you drive can lull your brain and body.

The team worked with 15 volunteers who were placed in a virtual driving simulator. The test pitted each participant against a monotonous, two-lane highway. It wasn’t the actual driving experience that was central to this experiment, however — what the team wanted to see was what effect car vibrations have on the volunteers’ alertness levels.

The simulator was installed on a platform that could vibrate on different frequencies. Each volunteer was tested twice, using the same 60-minute driving scenario, once with vibrations at low frequencies (4-7 Hz, the same range you’d experience in a car) and once with no vibrations (as a control test).

To gauge participants’ alertness, the team monitored their heartbeat. The researchers explain that tiredness induced by vibration makes it harder, both psychologically and physiologically, for people to perform mental tasks. In order to compensate, the body’s sympathetic nervous system alters the rate with which our hearts beat. So, by looking at each volunteer’s heart rate variability (HRV), researchers were able to gain an objective measure of how drowsy they were feeling as the test progressed.

Driving simulator.

The simulator rig used in the study.
Image credits RMIT University.

During the vibrating test, volunteers started showing signs of drowsiness roughly 15 minutes in. By the 30 minute mark, they showed significant drowsiness and required substantial effort to maintain alertness and cognitive performance. The effect was progressively stronger as the test drew on, peaking at 60 minutes.

Co-author Mohammad Fard, an Associate Professor at RMIT, said that the results warrant further research into the effect of these vibrations on people. One of the first areas that should be investigated is whether their effect is consistent across different demographics, he adds — as the current experiment used a relatively tiny sample size.

“We want to study a larger cohort, particularly to investigate how age may affect someone’s vulnerability to vibration-induced drowsiness as well as the impact of health problems such as sleep apnea,” he said. “Our research also suggests that vibrations at some frequencies may have the opposite effect and help keep people awake.

“So we also want to examine a wider range of frequencies, to inform car designs that could potentially harness those ‘good vibrations’.”

“To improve road safety, we hope that future car seat designs can build in features that disrupt this lulling effect and fight vibration-induced sleepiness,” added Robinson.

The paper “The Effects of Physical Vibration on Heart Rate Variability as a Measure of Drowsiness,” has been published in the journal Ergonomics.

The lattice-shaped electrode in the foreground, and the elastomer in the background.

Inteligent shock absorbers dampen vibrations and generate power

Many efforts and funding have been put into countering vibrations, such as the ones produced by an internal combustion engine, to dampen shocks and reduce noise. Much progress has been made; you only need to compare two vehicles, one twenty years old, the other brand new, and you’ll instantly notice the differences. One, noisy and bumpy, the other silent and smooth to cruise.

There is still room for much improvement. Engineers at the Fraunhofer Institute for Structural Durability and System Reliability LBF in Darmstadt are now researching the next generation of damping elements – active elastomers.

Elastomers are highly elastic materials, most common of which being rubber, which are well suited for absorbing shock and are widely used in the field. The researchers intend on brining shock absorbing a step further, or better yet a step back – making elastomers actively react to vibrations before they get the chance to produce shock.

The lattice-shaped electrode in the foreground, and the elastomer in the background.

The lattice-shaped electrode in the foreground, and the elastomer in the background.

Imagine a top tennis player slowing the ball down on a single drop by pulling back the racket. The active elastomer envisioned by the scientists would relatively employ the same principle, drawing out the energy from vibrations through a precise push-pull mode. In theory, vibrations would dissipate completely, in practice they’d be rendered to a minimum. Worst case scenario, active elastomers are a lot more efficient than any other conventional elastomer currently used today.

The concept isn’t new, however. Materials that are similar in principle have already been developed. “They are called ‘electroactive elastomers’,” explains LBF scientist William Kaal. “They are elastic substances that change their form when exposed to an electrical field.

An applied alternative current makes the material vibrate, and if you have smart electronics applying current precisely when and where it is necessary on the material to make it vibrate in a push-pull manner, then unwanted vibrations would be easily dissipated in the most part.

To demonstrate their concept, the researchers developed a model  made out of 40 thin elastomer electrode layers, fitted with  microscopic-sized holes in the electrodes. “If an electric voltage deforms the elastomer, then the elastomer can disperse into these holes,” said Jan Hansmann. The result is an actuator that can rise or fall a few tenths of a centimeter upon command – several times a second

The device then had a small mechanical oscillator attached to it to impose vibrations. When the oscillator was turned on, the actuator soon followed its oscillations and perfectly resonated with its frequency. If the oscillator is tapped by hand, it quickly settles down when the actuator vibrates in push-pull mode.

“An engine’s vibrations can be really disruptive,” says William Kaal. “The vibrations are channeled through the chassis into the car’s interior, where the passengers start to feel them. Active elastomers may help further reduce vibrations in the car,” Kaal asserts.

When the stack actuator is reversed, from producing vibrations, to absorbing them from the environment, it produces energy. The scientists introduced an electromagnetic oscillator on their stack actuator, it converted the vibrations into power. On the same subject, read: Nanotech powered by your breath.

 “That would be of interest, for example, if you wanted to monitor inaccessible sites where there are vibrations but no power connections,” Jan Hansmann believes – as he cites an example: the temperature and vibration sensors that monitor bridges for their condition.

source: physorg

cymbal

See how a cymbal wobbles at 1000 frames/second

cymbal

I’ve always liked drumming, and a masterful cymbal stroke is always a sign of good playing. I never once imagined, though, how complicated its motion of vibrations actually is, like demonstrated in the 1000 framer per second shot video from below. It actually wobbles when struck, similar to how waves might seems to juggle. Totally fascinating.

The video was shot by Fluke as part of its recent marketing campaign for company’s measurement instruments. Here’s another one from the same campaign right below, which shows in the same slow-mow technique a wet puppy shacking it off.

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