PH Origins: Road-scanning suspension


On 15 May 2013, the sixth-generation 'W222' Mercedes-Benz S-Class was unveiled in Hamburg. Befittingly, for a new flagship, it was equipped with a battery of advanced technology - including a semi-autonomous cruise system, airbags integrated into the seat belts and all-LED illumination.

Also highly touted was the 'Road Surface Scan' feature, part of the optional 'Magic Body Control' system, which let the S-Class detect and prime itself for upcoming bumps and surface imperfections.


The system's windscreen-mounted camera would look 15 metres ahead, then relay relevant data to the Magic Body Control - an active hydraulic suspension system. This would then adjust the load and damping at each wheel on the fly, reputedly adapting to the oncoming terrain in a fraction of a second and delivering a 'flying carpet'-style ride.

There were limitations to its capabilities, of course. Visibility needed to be good for it to work properly, and certain road surfaces and conditions could prevent it from functioning as expected.

Regardless, the press release described the S-Class fitted with this system as 'the world's first car to be able to detect bumps on the road ahead'. Unfortunately, for Mercedes, this wasn't the case - and it had missed the chance to claim that headline by some 28 years.


In 1981, Nissan had introduced electronically adjustable shock absorbers that offered three modes, allowing drivers to tailor the way their car handled and rode. With a new Bluebird - and flagship equipment-laden Maxima model - around the corner, however, the company was looking for ways to further improve its existing technology.

Automation was deemed appropriate for flagship derivatives, leading to the work on an electronically adjustable suspension system that would automatically optimise the car's dampers for the conditions.

The result was a new sonar-based hardware package, patented in February 1984, called the 'Supersonic Suspension System'. It used an ultrasonic sonar, mounted in the nose of the car, to 'look' at the road in front of the car. Analysis of the data from the sensor allowed a processing unit to identify the upcoming terrain - for example, if it was smooth or undulating - and adjust the stiffness of the front and rear dampers to the most appropriate setting.

It didn't overlook what the driver was doing at the time, either; the central processing unit also made use of other inputs - including information from the brakes, engine and steering - in order to constantly tailor the suspension to its optimal mode. The range of adjustments was relatively limited, mind, with the control unit simply switching between soft, medium and firm configurations.


Nissan ultimately launched its seventh-generation Bluebird, codenamed U11, in October 1983. The Maxima version was later unveiled in October 1984 and, in range-topping Legrand specification, it was equipped with the Supersonic Suspension System.

The Supersonic option was soon made available in myriad models, including the 1986 Leopard and 1988 Cefiro - which also received speed-sensitive four-wheel steering, along with the sonar-based suspension hardware, in an equipment combination dubbed 'Duet-SS' by Nissan.

In any instance, according to reviews of the system when it was new, it had the desired effect - with it reputedly improving both handling and comfort, particularly on uneven roads. Nissan had even accounted for it potentially packing up, with all the shocks simply defaulting to a medium stiffness if an error occurred.

So, while clearly not as advanced as the Mercedes system - with a shorter range, lower accuracy, fewer suspension adjustments and less processing power - it's fair to say that Nissan's sonar-based suspension system was truly the first to take into account 'the road ahead'.

Lewis Kingston

 

 

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Comments (35) Join the discussion on the forum

  • donkmeister 18 Dec 2017

    After Nissan, but before Mercedes, I'm certain Citroen released a system on tbe C5 that scanned the road ahead for bumps and holes, adjusting the suspension on each wheel to cope.
    I can't seem to find anything about it though.

  • Lewis Kingston 18 Dec 2017

    donkmeister said:
    After Nissan, but before Mercedes, I'm certain Citroen released a system on tbe C5 that scanned the road ahead for bumps and holes, adjusting the suspension on each wheel to cope.
    I can't seem to find anything about it though.
    Do shout if you come across something concrete – I'll have a further look around for more details later, too. Always looking to add more to the mental archives!

  • Loplop 18 Dec 2017

    Lewis Kingston said:
    Do shout if you come across something concrete – I'll have a further look around for more details later, too. Always looking to add more to the mental archives!
    Whilst not quite as sophisticated, it is suitably geeky!

    Toyota TEMS smilehttps://en.wikipedia.org/wiki/Toyota_Electronic_Mo...

    I've been doing lots of research into computing in cars for an assignment at Uni so I've come across a few interesting oddities such as these!

    If you ever get bored look up the Bendix Electrojector (first electronic fuel injection system) and the Carnegie Mellon University's NavLab.

  • TooMany2cvs 18 Dec 2017

    donkmeister said:
    After Nissan, but before Mercedes, I'm certain Citroen released a system on tbe C5 that scanned the road ahead for bumps and holes, adjusting the suspension on each wheel to cope.
    I can't seem to find anything about it though.
    No, everything Citroen hydraulic has been purely reactive, although it has adjusted springing and damping to conditions since the late 80s, and the Xantia Activa had full anti-roll in the mid 90s.

    The DS 7, though, has a camera-based system "reading" the road ahead.

  • Max_Torque 18 Dec 2017

    Hmm, not really. There is a rather important difference in the systems.

    The modern Merc system can scan the road far enough ahead, and modify the damping profiles quickly enough to be able to compensate for INDIVIDUAL road surface profiles in real time ie before the car hits the bump it's scanned.

    The old Nissan system could just basically say "this road is bumpy" (on average) and put change the damping to suit. That is really not very useful as it's reacting to what has gone and not to what is coming!


    What that means is the Merc system can be nice and stiff to control the secondary ride, but soften off an individual wheel to limit the affect of large primary ride event (ie a pot hole).

    This is why Merc are correct to make the claim they do for their system!

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