Explained: Clearmotion Proactive suspension

What is it?

Remember the Bose Ride suspension innovation that broke cover in 2004? Clearmotion bought that technology and is picking up where the consumer electronics company left off. Thanks to a fully active (‘proactive’) damper, the system gains a new level of control over wheel movement to deliver what is claimed to be an eerily smooth ride. The company has about US$100m invested in advancing the idea with its sights set on commercialising the technology for production cars.

4

Unlike Bose, which was targeting the luxury car market, Clearmotion sees greater potential in the emerging autonomous car arena. The system has already been miniaturised and lightened, resolving one of the hurdles experienced by the technology’s previous custodian.

How does it work?

With conventional suspension systems, the movement of the wheel is dictated by the surface it rolls over, or changes in speed and direction of the car. Modern adaptive dampers can alter the extent to which suspension resists movement but Clearmotion’s technology can actively compress and extend the suspension independently. Linear motors replace conventional suspension dampers. When voltage is applied to the motor, the wheel moves up or down in the arch depending on the polarity. In combination with sensors that read the road ahead, the system can move a wheel to roll over an obstacle with lessened impact on the car body.

4

Why does it matter?

With more control over suspension movement, the impact of bumps on the car and its occupants can be reduced, to increase comfort, while a reduction of bodyroll in corners and dive under hard braking brings dynamic benefits. Clearmotion sees greater potential with the advent of self-driving cars, however. The theory goes that passengers are willing to tolerate a degree of movement when they are aware of their surroundings, but in an autonomous vehicle, occupants might be preoccupied by other tasks.

Reducing the amount of disturbance felt in the cabin will make typing or reading easier, for example, and would reduce the likelihood of motion sickness. The system can also be configured to regenerate electricity, reducing the net power it consumes and extending the range of EVs that adopt the technology.

4

Sound principles

The idea behind Clearmotion’s proactive suspension is the same as that behind an audio speaker. When current is applied to a coil of wire, the magnet is repelled forcing the speaker cone to move, creating a sound wave. In the case of the suspension, the cone is replaced by a bar connected to the suspension arm. When the control system senses a lump in the road ahead, a signal is sent to the coil forcing the wheel to move before it hits the obstacle.