Bose (of speaker fame) designs electromagnetic car suspension | Hacker News Reader

Bose (of speaker fame) designs electromagnetic car suspension

edmunds.com

15 pointscharzom6 comments

This will actually make cars handle worse unless it's redesigned in one of two non-trivial ways. The problem is camber: the side-to-side tilt of the wheel and tire. Bringing the top of the wheel closer to the center of the car is called "negative camber" while the opposite is "positive camber". Most modern cars have a little bit of negative camber, which increases as the suspension is compressed. The relationship of compression to camber is called the "camber curve".

When the tire is being deformed by cornering forces, negative camber helps more of the tire stay in contact with the road. When traveling in a straight line, negative camber reduces the tire's contact with the road and increases tire wear. The reduced contact is visible on the left rear tire in the fourth photo.

One solution is to design a suspension with a very fast camber curve and allow minimal compression when cornering. This is similar to what most sports cars already do, and has a couple problems of its own. Such a suspension design is more limited in the distance the wheel can travel upward and has somewhat less traction on bumpy surfaces.

Another solution is to have a separate motor to adjust camber. That's expensive and heavy, but would probably work pretty well.

With an SLA suspension, you could just increase the ratio of bottom arm length relative to top arm to get a faster camber curve. But judging by the pic they plan on using this in McPherson style setups. Even if they left the camber settings the same though, the tire contact should still be better with the reduced roll. Increased roll angle will cause more positive camber than the camber curve will decrease it due to suspension compression. This is the reason why you typically go with more negative camber when you soften a suspension setup.

A setup like this would not work well for a few other reasons too. Like on a sports car, it would have problems with heat I can guarantee it. Looking at the pic it already has heat sinks all over the place, but in a race situation the heat emission would be totally ridiculous. As far as handling goes, it could have problems with grip when cornering hard over bumps. The outside wheel would essentially behave like having a damper with very high bump stiffness. I know they claim it has fast response time, but it would need to have very high resolution to still absorb bumps when it is basically holding up that corner of the car. Oh, and its damn heavy...

This tech has been around for years. I wonder why they haven't got it in production vehicles yet?

Bose Whitepaper: http://www.bose.com/pdf/technologies/bose_suspension_system....

If this is anything like Bose products of the past, I'm willing to bet that:

1) Bose wont release any technical specs (b/c apparently those dont matter in loudspeaker design)

2) It will be overpriced.

3) It will be over hyped.

Here's a bose site that has much more info about the system: http://www.bose.com/learning/project_sound/suspension_challe...

Video is included on the last page.

Active suspension is the natural language processing of automotive industry -- it's a good idea, and can be made to work well enough in the lab, but just isn't as good as conventional suspension with the same cost.

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