Auto Manifesto

August 27, 2009

Effectiveness of Anti-Lock Brakes

NHTSA published a reqeust for comments in yesterday's Federal Register about a Technical Report on The Long-Term Effect of ABS in Passenger Cars and LTVs (based on 1995 to 2007 data), some good some not really... Here are the basic findings:

1. "ABS has close to a zero net effect on fatal crash involvements."

2. Fatal run-off-road crashes of pass cars increased 9%.

3. Fatal collisions with pedestrians decreased 13%

4. Collisions with other vehicles on wet roads decreased 12%.

5. "ABS is quite effective on nonfatal crashes, reducing the overall crash-involvement rate by 6% in passenger cars."

Here's the link: text, PDF

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February 5, 2008

More Use of Magneto Rheological Dampers

As vehicles get lighter in the future there’s going to be more need for variable shock absorbers such as magneto rheological (MR) dampers. The reason is because as vehicle mass goes down but payloads (passengers) stay about the same, the payloads will make up a larger percentage of the overall mass, and suspensions are going to become more sensitive to changes in payloads. It becomes more difficult to make the vehicle meet performance criteria with regular (passive) dampers over the same variety of conditions.

Consider that on a bicycle you can use your body weight to drastically influence the dynamics of a bicycle, less so on a motorcycle, and not much in a regular car. Active suspension will be the key to improving handling, comfort, and safety.

Considering that MR dampers are proven, have been deployed in some higher end vehicles such as Ferraris, Corvettes, and Audis, it is only a matter of time before they migrate further down market. Here’s a brief summary of MR dampers from Wikipedia.

Now, I want to tie this in with a few other thoughts. Regenerative braking is widely used with hybrid vehicles. It captures kinetic energy that would otherwise be dissipated by brakes as heat to the atmosphere. Dampers also take kinetic energy from suspension movement and ultimately dissipate it to the atmosphere as heat. And they’ve been known to overheat in extreme conditions such as racing.

The second thought is that there are watches and flashlights, among other devices, that convert motion to electricity.

Would it be possible to develop a suspension system that uses a smart fluid to provide better vehicle handling and at the same time generate the electricity needed to control it from its own damping action, maybe even power accessories on the vehicle?

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