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Tuesday, 14 February 2012

A Suspension System with Smooth Moves

Feb 14, 2012

Credit: ASME

"Don't drink and drive ... you might hit a bump and spill your drink." So goes one of the stupider attempts at bumper sticker humor. Someday soon, though, the drivers of the world will no longer get the joke. Once the active electromagnetic suspension system developed by Bart Gysen, a researcher at Eindhoven University in the Netherlands, hits the road, folks behind the wheel will have a much better chance of keeping their drinks in their cups.

The Design

Gysen's design is a simple one in appearance. Inside the suspension spring that keeps the car levitated is an aluminum cylinder containing high-powered magnets. The cylinder also acts as a passive suspension system as a safety backup. The active system uses only 75 watts of energy, about the amount needed to power a car's air conditioner. The cylinder also regenerates energy, using the bumps in the road to power itself. If Gysen, or an auto manufacturer, were willing to discard the passive portion of the system, the active suspension would power itself 100%.

There are three sensors on the front of the car that measure the wheels' movement in relation to the road and the body of the car. It takes only milliseconds for the information to be translated into a reactive force from the magnets. The result is a ride that cuts down on jolts by 60%.

That percentage would be even higher if the road and its undulations could be measured before they got to the wheels, perhaps with lasers that read the terrain

in front of the car. Somehow, though, the system would have to know the material of the road, be it ice, pavement, wet leaves, or cream cheese. For now, Gysen is sticking with his trio of sensors.

Bart Gysen and a test car fitted with the new suspension system. Photo: Eindhoven University.

Control and Comfort

An active suspension has other advantages in addition to comfort. Typically, a car taking a sharp turn (or even a dull one) has a weight shift from one side to the other. The two inner wheels end up taking the lion's share of the force and lose a percentage of their traction. This can result in a loss of control or worse, a tipping or flipping of the car. Gysen's system can keep the weight of the car evenly distributed over all four wheels, so that the vehicle remains parallel to the ground throughout a turn. "You can put the gravity back in the center of the car, and get a better grip on the road," says Gysen.

Smart programming will tell the system when control is needed over comfort and when comfort trumps all. (It's easy to imagine, though, a system where the driver could choose, with the push of a button, between race-car mode and limo mode). The size and shape are the same as traditional suspension systems and can fit right onto the body of any car.

At the moment, the only prototype resides on the test vehicle, a BMW 530. While including the system on future vehicles might seem like a no-brainer, the automotive industry is currently guarding its coffers and is less than willing to lighten them for the research and development needed to put Gysen's invention on pavement. "It's not a bright future," bemoans Gysen. "There's no market pull at the moment. But if the system shows its advantage in the public, then there will be much more attention."

If consumers want active suspension, it seems manufacturers have to end suspension of action.

Source: ASME

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