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Comment by maxxxxx | Hacker News Reader

I thought there are already plenty of active suspension systems on the market or is this different?

The Mercedes ABC (Active Body Control) system is good. But if you watch the video - this one is amazing.

The Mercedes system used hydraulics. If the Bose system works the same way their truck seat does (the "Bose Ride") then it's run by a combination of pneumatic & electromagnets, and I'd be curious how they get enough current to run it.

ABC: https://www.youtube.com/watch?v=clyUmA5lRcg

Bose suspension: https://www.youtube.com/watch?v=q8sVDenpPOE

Bose Ride: https://www.youtube.com/watch?v=T_G9GCpWAcM

Mercedes ABC is actually the same as Citroen's much earlier hydropneumatic suspension. Its been around since WWII and in major production cars since at least the 1950s (the great Citroen DS)

Is that similar to the Austin 1800 and Morris 1100 hydrolastic suspension?

"it floats on fluid!

They were great cars to drive.

http://www.elevenhundred.com/hydro.php

https://en.wikipedia.org/wiki/BMC_ADO17

I think the updated version is called Magic Body Control [1] and the videos show an impressive behavior. But when this tech came out a couple of years ago, Autobild have tested it thoroughly and said that it works well on big bumps, but on everyday small street bumps and cracks that you mostly see on the streets, there was no effect. And it costs additional ~10k EUR...

[1]: https://youtu.be/ScpgI1w5F6A

I'm guessing that's what makes it viable.

If it's going into future vehicles, well, a number of those are going to have plenty of current.

That suspension would make a pretty sweet market differentiator for electric cars. Would go a long way toward making up for range anxiety.

There's been talk of switching to 48v batteries in cars (for the starter and accessory circuits, not for the EV circuits which already run at much higher voltages). AFAIK, only some Class B RV makers are using them for their house batteries.

They claim that it responds faster. Following the article's link to the source AutoCar article, there's this quote:

> “Our technology is the fastest proactive ride system that exists today,” Clearmotion CEO Shak Avadhany told Autocar in an exclusive interview.

There may be other differences. I'm not very knowledgeable about all the active suspension systems available, but it seems that the most common system today may be MagneRide:

https://en.wikipedia.org/wiki/MagneRide

This is basically a shock absorber but with some magnetic fluid inside it whose viscosity can be adjusted. So it does not move the wheels up and down, it just adjusts the opposing force. Though it can do it quickly.

There is one system on the new Audi R8 that does more:

https://www.audi-mediacenter.com/en/press-releases/looking-a...

This seems very similar to what the Clearmotion system does, as the above AutoCar article says the Clearmotion system "works by turning a car’s dampers into actuators".

So it seems the Audi R8 system and the Clearmotion system are doing similar things, but the Audi system does it "18 times a second" whereas Clearmotion technology page ( http://www.clearmotion.com/technology ) says "it only takes five milliseconds for the Activalve’s motor to counteract", so apparently 10 times as fast.

The problem with magnetorheological fluid dampers is that they wear out very quickly compared to conventional dampers. The magnetic particles are basically very fine grit, which abrades away at the valving inside the dampers.

The active suspension systems I have seen let you switch suspension profiles on the fly. Some are advertised with "millisecond" response time implying automatic tuning based on force sensors. This demo shows aggressive predictive tuning.

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