The Bose Active Suspension Lives! (On a Chinese Luxury Sedan)
Boston-based ClearMotion bought the Bose IP and swapped electrohydraulic for electromagnetic actuation. China’s Nio ET9 is first to put it in production.
If you haven’t seen the video from 2004 of a Lexus LS400 performing a steeplechase jump, Google it and lament the fact this electromagnetic suspension—under development for 24 years by then—never ended up suspending a volume production car (it did cushion some heavy-truck seats). But Boston neighbor ClearMotion acquired the Bose Ride business in 2017 and has continued to develop the concept. Chinese EV startup Nio was among ClearMotion’s investment partners, and it inked a contract for 750,000 vehicles’ worth of ClearMotion1 suspensions, making it the first manufacturer to put the system in production under the name "SkyRide." We recently sampled it on the Nio EV9.
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Electrohydraulic, Not Electromagnetic
Turns out scaling a doorbell plunger or speaker-coil driver up for car suspension duty just couldn’t pencil out, but ClearMotion applies much of Bose’s control logic to its suspension, which packages a proprietary gerotor hydraulic pump and reservoir at each corner. These units can adjust a wheel’s position up or down 60 times faster than an air spring can. To do this, the pump motor makes 1,000 torque adjustments per second in response to actuators with a response time of 40 adjustments per second while moving the wheel through a total range of motion of 108mm. Note that while Bose proposed steel torsion bar springs to bear the vehicle’s load while its rams handled damping and leveling, the ET9 uses air springs for these purposes. (This is a major difference between the ClearMotion1 system and the purely hydraulic active corners we covered by Domin.)
Reactive Now, Fully Active Soon?
Bose and ClearMotion both propose reactive suspensions fitted with ultrafast responding sensors, but everyone knows that a suspension that knows the precise size and placement of a bump can better prepare to actively cushion it. All the recent higher-end Nio vehicles are cloud connected, and every one of them has been using their onboard sensor suite to map the road for bumps and potholes, but to date that data isn’t quite accurate enough to inform SkyRide. But these new suspension corners are far more accurate at road sensing, so as the fleet of ET9s increases, the high-def map of road irregularities will improve. The companies are also working to train the ADAS sensor suite to better measure and report road irregularities, both to their own onboard suspension corners and to the cloud. All of this promises to make an ET9 purchased today potentially ride better tomorrow.
Edge Use Cases
Along with the ability to kneel for easier entry/egress/cargo loading, or to rise in an instant to better align the car’s skateboard structure with another vehicle’s bumper prior to an impending impact, the ET9 has some other party tricks. Its suspenders can be made to dance on command. There’s a suspension demo mode, in which the front center screen plays videos of different road surfaces, depicting the ride quality a “normal” car might provide, with the suspension acting out the bumps, then plays them back in SkyRide mode for contrast. Then there’s also the world’s first production example of 5D PanoCinema mode, in which the car can be made to shake and vibrate in conjunction with action in a movie playing on the screen(s). But perhaps our favorite is “Soccer Maze,” a gaming demo in which the car can be connected to a Nio Phone 2 (yes Nio makes phones now, too) via Bluetooth, allowing the phone’s gyroscope to control pitch and roll while a tabletop football game on the roof moves the ball around.
How Much Power Does SkyRide Draw?
Nio engineers were pretty cagey on this topic, but translating one of the graphics in a SkyRide presentation noted a power figure 10kW. That has to be a max draw rate during 5D PanoCinema use with a lot of up and down motion, because there’s no reason these units should draw significantly more power than the Domin ones, which were quoted at 1kW during a ride height increase adjustment. There should be no significant power draw while riding down a smooth road.
How Does It Ride?
Remembering that we’re still sampling the system before it’s totally cloud-informed, it rides very smoothly, but not cloud-like. You still sense all the bumps as the system reacts and greatly lessens their effect. It is exceptionally good at bridge ramps (these it can prepare for). The suspension rises a little in advance, absorbs the uphill ramp, levels off, and descends the other side with exception grace. And experiencing the demo, which showed a road very like one we’d driven on near the Nio headquarters with rubber speed bumps applied, the difference before and after engaging SkyRide was stark, and the after felt representative of our experience on that road. We also watched folks watching a movie with cars bucking like broncos on an extremely rough course, and the car impressed by matching the action faithfully.
When Might We Get ClearMotion1?
Porsche signed a licensing deal with ClearMotion in April 2024 and we’re told others will be announcing similar deals soon. Nio also has technology sharing agreements with McLaren. So expect this tech to make it’s North American debut on something expensive.
But Will It…Fly?
We seriously doubt these gerotor pumps have the speed, power, and fluid capacity needed to launch 2.5 tons of luxury sedan skyward. But we’d definitely click on a video of it doing so.
I started critiquing cars at age 5 by bumming rides home from church in other parishioners’ new cars. At 16 I started running parts for an Oldsmobile dealership and got hooked on the car biz. Engineering seemed the best way to make a living in it, so with two mechanical engineering degrees I joined Chrysler to work on the Neon, LH cars, and 2nd-gen minivans. Then a friend mentioned an opening for a technical editor at another car magazine, and I did the car-biz equivalent of running off to join the circus. I loved that job too until the phone rang again with what turned out to be an even better opportunity with Motor Trend. It’s nearly impossible to imagine an even better job, but I still answer the phone…
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