Explanation of How M Adaptive Suspension Works

Racer20

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[COLOR="DarkRed"][SIZE="1"](This post was originally written in response to a question asking about the general limitations of adaptive suspension. When this ended up on the front page, all the discussion before my post was removed. Therefore, most of this post talks about the downsides, or things it CAN'T do. However, there are lots of benefits to these systems as well, or Automakers wouldn't be spending hundreds of dollars to put them on their cars.)[/SIZE][/COLOR]

TLDR:

• Yes, your aftermarket wheels/tires/springs/bars/spacers will make a difference
• These systems are very complex, once in a while they may do strange things under some outlier road/driving conditions, but in general are quite robust if well tuned
• They can't react perfectly to very small/very sharp bumps
• Requires a really good tuning engineer to fully optimize. Bad tuner = bad ride/handling.
• There are lots of bad tuning engineers out there.

THE LONG VERSION:

[COLOR="DeepSkyBlue"]How they work:[/COLOR]

These systems (excluding Magneride) usually work by having passive valves just like any shock absorber, and an active valve in parallel that makes the damping force change.

The ECU has a simulated model of the vehicle including all the suspension parameters (tire stiffness, spring/bushing rates, suspension geometry, wheel/body mass, etc.). Information from various sensors is run through this model to predict what the car is going to do, then the ECU sends a command to the shock, in the form of an electrical current.

When driving down a smooth road, the active valve is fully open, and the damper is in full soft**, or some "steady state" setting close to it. When the sensors detect a large swell, pothole, choppy pavement, etc., or if you turn the steering wheel or brake or whatever, the ECU does the math and sends some current to the active valve solenoid for a split second. The valve gets stiffer, the damping force increases to deal with whatever is going on, then it drops back down to the soft setting. This all happens in fractions of a second.
[COLOR="DarkRed"]
**(Note that "full soft" is /= comfort mode. Full soft means no current being sent, no active control, absolute minimum damping force. Comfort mode typically has some level of active control, just less of it than normal and sport modes)[/COLOR]

[COLOR="DeepSkyBlue"]Some limitations:[/COLOR]

1. Road conditions
Very Small Bumps
Some events, like pavement cracks, roads with a coarse texture, or very small, light undulations, are too small or too fast to detect and/or react to. In these cases, no current command is sent, and the performance will depend on how the full soft mode was tuned. Also, instant response to every road input isn't really ideal either. If the damper reacts to every single tiny bump on the road, it can cause the ride to become busy and jerky. For example . . . Magneride has much faster response time potential, but they have to put an artificial threshold there anyway to prevent this issue.

Very Sharp Bumps
Larger events that are very sharp, like your pavement transition or a manhole cover, occur too quickly for the damper to react in the ideal manner. Its possible that the full soft mode isn't soft enough for these bumps, but it's more likely that the harshness you feel is actually a result of not enough damping at the instant that you first hit the impact. With lower damping, the tire kicks off the impact rather than enveloping it, and you get more/faster wheel motion than you would if you had more damping. This limitation will affect the body's reaction to the initial kick as well as how the wheel and body settle after the bump. If you bring in more damping faster at the initial impact, you can improve the impact quality on sharp bumps, but again, the ride can get jerky and busy on other types of roads. It's still all a compromise.


2. Adaptability and Hardware
The model in the ECU isn't perfect, and how not-perfect it is depends on many things. One trend now is to reduce the number of sensors on the car to save money. When we're tuning, we have all kinds of high precision accelerometers, height sensors, yaw sensors, GPS, etc. on the car to measure what it's doing. But the production car may only have 4 height sensors to go by, and they may be less precise than we would like. So we have to do some fancy math to know what the car is doing, which means it takes longer and the result is less accurate.

As far as your wheels and tires go:
The difference between your old and new wheels may not seem like much, but in engineering terms, an 18mm offset difference in the rear is HUGE, and will definitely affect the accuracy of the model. Say for example that 18mm equates to a 10% increase in suspension lever arm length. That means the damper will have to make 10% more force in order to get the same level of control as before, but the ECU doesn't know that!. That's before we talk about width, diameter, tire stiffness, scrub radius, etc, etc.

3. Lots of things going on at once
If you hit a pothole in a corner while braking over a large swell, the ECU has to prioritize all those different events to decide what command to send. 1st priority would be to make sure the car is controlled and safe, then to prevent wheel/tire/body damage in the pothole, then other comfort and handling concerns.

4. Complexity of tuning
Semi-active shocks are some of the most complex, non-linear, un-model-able mechanical components on a modern car, and the car is EXTREMELY sensitive to very small changes in their behavior. These systems can cost the OEM up to $ or more, which is a big chunk of change for just 4 shocks and some sensors. When we're tuning these things, we make changes on the order of a couple pounds of force, and that results in big changes to the car's behavior.

My point is that these things are very difficult and time consuming to tune, and if the tune isn't robust and the algorithm doesn't properly account for all roads and conditions, the car might do strange things under some circumstances. IMO, only in the past couple years has the hardware, software, and engineering capability come together for semi-active suspensions to be really good. Even then, it depends HEAVILY on the tuning engineers skills and knowledge.

I believe the F30 Adaptive Dampers are made by Tenneco. I haven't driven one of their systems, but from what I know, this system is a bit behind the current state of the art. [COLOR="DarkRed"](Edit: this technology is advancing very quickly these days, so their system on the 4 series or 2 series will have a different tune and may use different valves or software, and may be better than the F30.)[/COLOR] Sachs has some valve-based systems that are really good, and GM's latest Magneride cars are really good. Things are advancing pretty rapidly in my field right now, so within the next couple years these systems should be even better.
Edit Jan 11, : this post is pretty old but I see that people are still reading it, so a little disclaimer: technology moves quickly in the field of electronic suspension. Main points are still accurate but take it with a grain of salt, as it likely doesn't reflect the latest state of technology, especially on G series cars.

[COLOR="DeepSkyBlue"]My Personal Thoughts . . .
[/COLOR]
All said and done, a GOOD adaptive system can be much better than any passive system if properly tuned. I've heard mixed reviews of the F30 system, and I'm having a hard time finding one locally to test drive. Regardless, I've decided that my next car will have an adaptive system . . . I've just got to find one that meets my high standards. Unfortunately the stuff I'm working on now won't be on the market for a few more years, so I'm kind of stuck hoping the other guys have tuned something that I like.

I'm a chassis engineer and I develop adaptive suspensions systems. This will be long.[COLOR="DarkRed"][SIZE="1"](This post was originally written in response to a question asking about the general limitations of adaptive suspension. When this ended up on the front page, all the discussion before my post was removed. Therefore, most of this post talks about the downsides, or things it CAN'T do. However, there are lots of benefits to these systems as well, or Automakers wouldn't be spending hundreds of dollars to put them on their cars.)[/SIZE][/COLOR]These systems (excluding Magneride) usually work by having passive valves just like any shock absorber, and an active valve in parallel that makes the damping force change.The ECU has a simulated model of the vehicle including all the suspension parameters (tire stiffness, spring/bushing rates, suspension geometry, wheel/body mass, etc.). Information from various sensors is run through this model to predict what the car is going to do, then the ECU sends a command to the shock, in the form of an electrical current.When driving down a smooth road, the active valve is fully open, and the damper is in full soft**, or some "steady state" setting close to it. When the sensors detect a large swell, pothole, choppy pavement, etc., or if you turn the steering wheel or brake or whatever, the ECU does the math and sends some current to the active valve solenoid for a split second. The valve gets stiffer, the damping force increases to deal with whatever is going on, then it drops back down to the soft setting. This all happens in fractions of a second.[COLOR="DarkRed"]**(Note that "full soft" is /= comfort mode. Full soft means no current being sent, no active control, absolute minimum damping force. Comfort mode typically has some level of active control, just less of it than normal and sport modes)[/COLOR]Some events, like pavement cracks, roads with a coarse texture, or very small, light undulations, are too small or too fast to detect and/or react to. In these cases, no current command is sent, and the performance will depend on how the full soft mode was tuned. Also, instant response to every road input isn't really ideal either. If the damper reacts to every single tiny bump on the road, it can cause the ride to become busy and jerky. For example . . . Magneride has much faster response time potential, but they have to put an artificial threshold there anyway to prevent this issue.Larger events that are very sharp, like your pavement transition or a manhole cover, occur too quickly for the damper to react in the ideal manner. Its possible that the full soft mode isn't soft enough for these bumps, but it's more likely that the harshness you feel is actually a result ofat the instant that you first hit the impact. With lower damping, the tire kicks off the impact rather than enveloping it, and you get more/faster wheel motion than you would if you had more damping. This limitation will affect the body's reaction to the initial kick as well as how the wheel and body settle after the bump. If you bring in more damping faster at the initial impact, you can improve the impact quality on sharp bumps, but again, the ride can get jerky and busy on other types of roads. It's still all a compromise.The model in the ECU isn't perfect, and how not-perfect it is depends on many things. One trend now is to reduce the number of sensors on the car to save money. When we're tuning, we have all kinds of high precision accelerometers, height sensors, yaw sensors, GPS, etc. on the car to measure what it's doing. But the production car may only have 4 height sensors to go by, and they may be less precise than we would like. So we have to do some fancy math to know what the car is doing, which means it takes longer and the result is less accurate.The difference between your old and new wheels may not seem like much, but in engineering terms, an 18mm offset difference in the rear is HUGE, and will definitely affect the accuracy of the model. Say for example that 18mm equates to a 10% increase in suspension lever arm length. That means the damper will have to make 10% more force in order to get the same level of control as before,. That's before we talk about width, diameter, tire stiffness, scrub radius, etc, etc.If you hit a pothole in a corner while braking over a large swell, the ECU has to prioritize all those different events to decide what command to send. 1st priority would be to make sure the car is controlled and safe, then to prevent wheel/tire/body damage in the pothole, then other comfort and handling concerns.Semi-active shocks are some of the most complex, non-linear, un-model-able mechanical components on a modern car, and the car is EXTREMELY sensitive to very small changes in their behavior. These systems can cost the OEM up to $ or more, which is a big chunk of change for just 4 shocks and some sensors. When we're tuning these things, we make changes on the order of a, and that results in big changes to the car's behavior.My point is that these things are very difficult and time consuming to tune, and if the tune isn't robust and the algorithm doesn't properly account for all roads and conditions, the car might do strange things under some circumstances. IMO, only in the past couple years has the hardware, software, and engineering capability come together for semi-active suspensions to be really good. Even then, it depends HEAVILY on the tuning engineers skills and knowledge.I believe the F30 Adaptive Dampers are made by Tenneco. I haven't driven one of their systems, but from what I know, this system is a bit behind the current state of the art. [COLOR="DarkRed"](Edit: this technology is advancing very quickly these days, so their system on the 4 series or 2 series will have a different tune and may use different valves or software, and may be better than the F30.)[/COLOR] Sachs has some valve-based systems that are really good, and GM's latest Magneride cars are really good. Things are advancing pretty rapidly in my field right now, so within the next couple years these systems should be even better.Edit Jan 11, : this post is pretty old but I see that people are still reading it, so a little disclaimer: technology moves quickly in the field of electronic suspension. Main points are still accurate but take it with a grain of salt, as it likely doesn't reflect the latest state of technology, especially on G series cars.[COLOR="DeepSkyBlue"][/COLOR]All said and done, a GOOD adaptive system can be much better than any passive system if properly tuned. I've heard mixed reviews of the F30 system, and I'm having a hard time finding one locally to test drive. Regardless, I've decided that my next car will have an adaptive system . . . I've just got to find one that meets my high standards. Unfortunately the stuff I'm working on now won't be on the market for a few more years, so I'm kind of stuck hoping the other guys have tuned something that I like.

Last edited by Racer20; 04-09- at

10:09 AM

..

Imagine a car that constantly adjusts its suspension in response to changing road conditions in order to ensure a continuously smooth ride. This is basically what adaptive suspension does; it actively changes the configuration of the suspension in order to mitigate the impact of potholes, bumpy roads, and other impediments on the driving experience.

As we&#;ll explore further in this post, this allows adaptive (or active) suspension to offer drivers a better handling, feel, responsiveness, and safety.

How does adaptive suspension work?

Adaptive (or active) suspension systems use sensors and microprocessors to monitor the road beneath its wheels in real time. A computer reads the data as it&#;s sent over by the sensors and adjusts the shocks and springs to create a smooth driving experience.

The company is the world’s best cars with adaptive dampers supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

Is adaptive suspension worth the cost?

For those who have a long commute, drive frequently on bumpy roads, or just appreciate the feeling of a seamless drive, adaptive suspension can be well worth the price.

Which vehicles offer adaptive suspension?

As of the time of writing, adaptive suspension is offered as a standard or optional feature on these vehicles.

Acura Active Damper System

Acura&#;s adaptive suspension is only available on Sport Hybrid models.

Audi Adaptive Damping Suspension

Audi&#;s adaptive suspension is offered on the A4 and S4, A5 and Q5

BMW Adaptive Drive with Variable Damper Control

BMW&#;s adaptive suspension is available on the 5 Series, 6 Series, X6, and most Alpina models

Buick Continuous Damping Control Active Suspension

Buick&#;s adaptive suspension is available on the LaCrosse

Cadillac Magnetic Ride Control Adaptive Suspension

Cadillac&#;s adaptive suspension is an option on the ATS, CTS, and XTS

Dodge Adaptive Damping Suspension

Dodge&#;s adaptive suspension is offered on the Charger and Challenger

Ford Adaptive Suspension

Ford&#;s adaptive suspension is offered on the Ford Fusion Sport

Genesis Adaptive Control Suspension

Genesis&#; adaptive suspension is available on the G90

GMC Magnetic Ride Control Adaptive Suspension

GMC&#;s adaptive suspension is available on the Yukon and Sierra

Infiniti Dynamic Digital Suspension

Infiniti&#;s adaptive suspension is available on the Q50 and Q60

Jeep Adaptive Damping Suspension

Jeep&#;s adaptive suspension is available on the Grand Cherokee SRT.

Land Rover Adaptive Dynamics with advanced MagneRide

Land Rover&#;s adaptive suspension is available on the Discovery Sport and Range Rover Sport

Mercedes-Benz Active Suspension

Mercedes-Benz&#; has three different adaptive suspension systems: Agility Control is available on the C-Class, E-Clas, GLC-Class and GLE-Class; AIRMATIC is offered on the S-Class, CLS-Class and GLS-Class; Active Body Control is exclusive to the SL-Class

Porsche Active Suspension Management

Porsche&#;s adaptive suspension is available on the Cayenne

Toyota Adaptive Variable Suspension

Toyota&#;s adaptive suspension is offered on the Sequoia

Volkswagen Dynamic Chassis Control

Volkswagen&#;s adaptive suspension is available on the Golf R

Volvo FOUR-C Active Chassis

Volvo&#;s adaptive suspension is available on the XC90

Whether or not you want adaptive suspension in your new vehicle, Cartelligent can help you get a great deal on exactly what you want. Call our team of car-buying experts at 888-427- or get started today.

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