Talk:Active suspension

Formula 1
Both Williams and Lotus experimented with active suspensions. In the times of the "inverted-wing" cars, the goal was to provide a constant ride height throughout a lap. See for example the 1987 Lotus 99T-Renault. Later, with the new "flat-bottom" regulation, Williams developed a true active suspension, with computer-controlled length of travel and speed of movement. See for example the 1992 Williams FW14B-Renault. Aldo L (talk) 06:41, 21 November 2010 (UTC)

Citröen Hydractive system
The Citröen Hydractive system was actually the first mass-produced intelligent system that controlled the two most important parameters in the elasticity of a suspension system: its length of travel and its speed of movement. Most semi-active systems only control the speed of movement via the setting of the shock absorbers, but do not change the setting of the springs. (The Xantia Activa's novel feature was a further development of the constant-height system introduced in 1955 by the DS, this time adding lateral control to the longitudinal control. This feature do not change the setting of the suspension in any manner, though the Xantia was also equipped with the Hydractive system.) Pondering these capabilities, all Citröen Hydractive systems would thus qualify as active systems. Aldo L (talk) 06:50, 21 November 2010 (UTC)


 * Years ago I read a piece in CAR magazine, authored by the late LJK Setright, which claimed that Citroen had a working system on a DS around 1959-60. I presume that cost and/or complexity in the pre-electronic era prevented it from reaching production.  the same article mentioned AP testing a system later in the 1960s, installed in, of all things, a Hillman Hunter. Mr Larrington (talk) 14:25, 11 August 2011 (UTC)


 * Fully active systems allow the controller total authority over the motion of the wheels and body, to within the limits imposed by their masses. As you reduce the power and bandwidth of the actuators, fully active segues into semi-active, such as variable ride heights, and then adaptive type systems such as variable passive damping and variable stiffness sta bars are even lower on the scale. I am pretty sure that Rolls Royce got seriously interested in an active system based on citreon's technology, but so far as I know neither citreon nor RR ever got close to productionising a powerful active system. Marketing people and fanbois love to refer to 'active' suspensions, but they are rare beasts. Certainly most of the suspensions listed as active in this article are mislabelled. Since, of course, marketing people write the PR blurb, and journalists swallow it whole, and fanbois write wiki articles, inevitably the silly marketing claims end up as cited statements. Oh well, nobody dies as a result, it really doesn't matter much.Greglocock (talk) 07:26, 22 August 2012 (UTC)


 * To answer the question of Citroen getting involved with Rolls Royce and others, its hydropneumatic suspension was fitted on the Mercedes-Benz 6.9 L: http://www.classicandperformancecar.com/front_website/octane_interact/carspecs.php?see=3446 — Preceding unsigned comment added by 174.116.2.222 (talk) 00:00, 4 October 2012 (UTC)

Automotive Products
Automotive Products (AP) did a Rover 3500 (2000 bodyshell, V8) which was fully active - all suspension by hydraulic cylinders, back in about 1975. It handled like a 911! Absorbed a lot of power (>50 hp from memory) and never went into production. — Preceding unsigned comment added by 103.247.246.119 (talk) 09:41, 23 May 2013 (UTC)


 * Gosh, and yet by 1978 they had scrapped it unlike all the other Rover and Triumph protos which they kept. Or perhaps, more likely, it never existed. Greglocock (talk) 12:00, 23 May 2013 (UTC)


 * Was it a prototype by Rover (the vehicle manufacturer) or a prototype by AP (third party)? And of course, we need some form of documentation.  Stepho  talk 22:05, 23 May 2013 (UTC)


 * I apologise, it was an AP project Rover weren't directly involved. http://www.tonyfoale.com/Articles/Active/active.htm
 * Greglocock (talk) 06:16, 24 May 2013 (UTC)

Yes the AP Rover V8 with fully active suspension did exist,I drove it at Leyland in about 1975 or so. It cornered very flat, but so much power was absorbed it was slower than a standard 3500S through a chicane. By the way I think we should differentiate "Fully Active" where all suspension is hydraulic apart from compliance in tyres and rubber bushes, from "Semi Active" - control of gross body movements like dive and roll, but a passive suspension is series, from "Adaptive" - alteration of suspension parameter (damping, anti-roll bar stiffness etc.). Calling "Adaptive" by the name of "Semi-Active" is wrong! Sort of thing Marketing people do!JohnBegg (talk) 07:05, 20 December 2016 (UTC)

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Active vs. Passive unclear
Article is not clear on what 'Active Suspension' really is.

According to some dictionary definitions, it is narrow, that application of electric servos or motors married to electronic computing powered by Lotus in the 1980's. This was of course not possible earlier, only possible due to advances in technology.

If on the other hand, it is wide - anything not-passive is active, that would encompass earlier systems that also addressed 'Skyhook theory,' beginning with Hydropneumatic suspension. If 'active' is not a good description of the 'non-passive' catchall grouping, then we need to clarify. PLawrence99cx (talk) 17:35, 21 April 2017 (UTC)


 * In my mind I use the following rough definitions:
 * Passive is when you have a spring and shock absorber combination that always responds the same to every situation.
 * Semi active is when you can alter the spring rate or damping rate - eg sports mode vs normal mode.
 * Active is when a mechanism raises or lowers the wheel (eg hydraulic rams, electric motors).
 * Might have to tweak these definitions a bit to handle the original Mini's Hydrolastic suspension and the Citroen DS's Hydropneumatic suspension, both of which could be considered active suspension but neither has any electronics.  Stepho  talk 00:20, 22 April 2017 (UTC)stem or


 * There was no control system or power supply for Hydrolastic. it was interlinked, not active (I worked on it briefly). Greglocock (talk) 03:54, 22 April 2017 (UTC)


 * True, which is why I pointed out that my rough definitions fail in those two cases. Perhaps active suspension should include something about each actuated being independent of the others (which rules out the Mini and DS systems).
 * Anyway, we're getting off topic a bit. The real question is about semi-active (ie those that only change the spring and damper rates). I'm happy to leave them here. We just need to spell out the 3-way differences a bit clearer in the article instead of just splitting them into passive and active.  Stepho  talk 08:53, 22 April 2017 (UTC)

Proposal : Active/semi active
Since semi active suspension has its own article why not get rid of all the semi active details from this page? Greglocock (talk) 22:41, 21 April 2017 (UTC)
 * ah it is just a redirect to this article. forget it. Greglocock (talk) 22:42, 21 April 2017 (UTC)

The list of cars
I think it would be worth editing the list and chucking out anything that is not a first or a significant milestone, and anything which incorrectly claims to be active but is semi active. Greglocock (talk) 23:11, 22 April 2017 (UTC)


 * Then what do we do with the semi-active cars?  Stepho  talk 23:18, 22 April 2017 (UTC)


 * Automatically adjustable shock absorbers? I don't know. I'm trying to come up with a classification system that would help, but self levelling cars are a great illustration of why defining active is so hard, and adding an external control to the damping rate of a shock absorber is also trivial these days - there are at least three ways of doing it.Greglocock (talk) 23:34, 22 April 2017 (UTC)


 * Here for example is the spectrum of stuff that hitachi makes for cars. http://www.hitachi-automotive.us/Products/oem/DCS/Suspension/index.htm If you put the self levelling springs, semi active shocks, and the roll control system all in one vehicle you have a low bandwidth, low authority, fairly cheap, active car. Greglocock (talk) 23:45, 22 April 2017 (UTC)

Agreed. The history list is so long as to be useless. Many look like new brand names for "me too" products - don't belong on this page. A history of first developments in "Non-Passive Suspension" with "Skyhook" as a guide for design makes sense. I would get rid of the list, and match each category to first use. Here is my proposal:
 * -Active - Hydraulically actuated. First engine powered, adjustable suspension on production car, which I believe to be 1955's Hydropneumatic suspension. The air compresses instantly to adjust to road obstacles, while the fluid under pressure allows for the system's "brain" to readjust the body in response to conditions automatically, but in seconds, not milliseconds.
 * -Active - Electronically controlled F1 car - application of electric servos and motors married to electronic computing pioneered by Lotus 92 from 1983. Williams Grand Prix Engineering prepared an active suspension for F1 cars in 1992, creating such successful cars that the FIA decided to ban the technology.
 * -Active - Active anti-roll bar - First production car where anti-roll bar stiffened under command of the suspension ECU during hard cornering was Citroën Xantia Activa in 1994
 * -Active - Electronically controlled (fully) production cars - Are there any?
 * -Semi-Active/Adaptive - Solenoid - First production car with semi-active suspension Toyota Electronic Modulated Suspension from 1983.
 * -Semi-Active/Adaptive - Magnetorheological damper Cadillac STS 2002
 * PLawrence99cx (talk) 00:34, 24 April 2017 (UTC)


 * Good job. AFAIK there are no /production/ cars with high power high bandwidth systems, and the low power low bandwidth systems are off the shelf, as I demonstrated with Hitachi's technology. To further confuse things, one could vary ride heights with switchable shocks only, no pump required, just by exploiting the jacking effect of high compression damping. Greglocock (talk) 01:19, 24 April 2017 (UTC)


 * Sounds like this framework is a good definition of Active and Semi-Active that encompasses the concept. To me the on-board "brain" is the key marker of Active, with high bandwidth solenoid systems driven by rapid computer processing distinguished as ''Fully Active." PLawrence99cx (talk) 23:29, 7 May 2017 (UTC)

Is variable ride height alone active suspension?
It is hard to claim that it isn't, since a power source and some form of feedback are required, but if it does qualify then it blows this whole article apart. For example the 1955 Citreon system was basically just a way of changing the ride height. Incidentally Lotus realised they were going to lose the PR game when the Infiniti came out. The Infinit system was very low bandwidth and aimed at ride more than handling with fairly limited authority, but /was/ active by any sensible definition, and of course enormously cheaper than the high bandwidth high power system Lotus were developing. Greglocock (talk) 23:20, 22 April 2017 (UTC)


 * My vote is if the car has a "brain" of some kind on board that regulates the suspension, then it is active. The electronics allow greater processing power, but just because ships today are made of steel, doesn't mean that a wooden ship is no longer a ship. PLawrence99cx (talk) 00:48, 24 April 2017 (UTC)

Skyhook
I gather that an editor once read an article about skyhook control theory and it is now plastered all over this article. Are all active suspensions based on skyhook theory, or is this wp:undue ? Greglocock (talk) 20:37, 14 December 2017 (UTC)

the list again
DeFacto rightly questions the parameters for this list. I suggest that it should be restricted to production vehicles (not prototypes) and should merely include the first example of each significant step in technology. I know that is somewhat subjective, but of Joe Bloggs had tunable shocks in 1992 I don't see why Boge/BMW introducing them in 1994 is worth mentioning, for example. However in the interim I'll bung in refs as I find them. Greglocock (talk) 20:52, 15 December 2017 (UTC)