Bose Active Suspension
11-13-2014, 09:29 AM
#9
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They do use magnetic fluid in shocks with electromagnets, but I think it is only on/off. If set up with control algorithms, it could be modulated to do more along the lines of Bose: single setting gives smooth ride and wheel control.
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11-13-2014, 09:32 AM
#10
The bose system are literally electric linear actuators. Think hydraulic cylinders but powered with electricity. The only thing they have in common with the shocks in our cars is that they fit in the same relative space. The rate at which they have the sense the road forces, compute the suspensions reaction and then actually perform it absolutely pushes the limit of what is physically possible with our current technology.
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11-14-2014, 06:37 PM
#11
^that would be sweet, but having used a big linear actuator (EMA shock dyno) that would require a rather large alternator. Our machine ran on 220v producing up to 1000 lbs force and would overheat after a minute or two of running. I guess the power consumption and resulting MPG penalty of an EMA suspension would be huge.
Very cool technology though.
Very cool technology though.
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11-14-2014, 07:33 PM
#12
There are major law suits happening now because GM keys failed to work properly. This was mainly due to customers adding about 10 pounds of crap to their key chains but hey, law suit.
Imagine what would result if these systems failed to work exactly as advertised.
The magnetic oil that changes viscosity on the fly is impressive. I think older systems (the Bose system?) used a piezo-electric valve in place of the stock shock shims. The magnetic ride seems like a natural progression from the valve as it does the same thing (alters valving), but with fewer moving parts to break.
Lotus had a system with sensors pointing at the road in front of the wheels that would alter the valving based on the road directly in front of it.
Imagine what would result if these systems failed to work exactly as advertised.
The magnetic oil that changes viscosity on the fly is impressive. I think older systems (the Bose system?) used a piezo-electric valve in place of the stock shock shims. The magnetic ride seems like a natural progression from the valve as it does the same thing (alters valving), but with fewer moving parts to break.
Lotus had a system with sensors pointing at the road in front of the wheels that would alter the valving based on the road directly in front of it.
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11-14-2014, 11:40 PM
#13
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Active suspension is legit, although very high dollar. Rumors are 2017 Mercedes S class will be so equipped.
For something a little closer to the aftermarket, see article titled "With Liberty and Electronic Dampers for All" in the December 2014 Motortrend.
Electromagnetic dampers have been around a while. But I don't know of any aftermarket nor OE that currently that have active suspension, which that Lexus clearly has.
For something a little closer to the aftermarket, see article titled "With Liberty and Electronic Dampers for All" in the December 2014 Motortrend.
Electromagnetic dampers have been around a while. But I don't know of any aftermarket nor OE that currently that have active suspension, which that Lexus clearly has.
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11-15-2014, 02:00 PM
#14
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There are various variations of similar themes:
The above bose system is "fully active" and "full bandwidth" (fast) in that each corners hydraulic ram (or other actuator) can both absorb or deliver energy (e.g. push a wheel down), in real time to react to bumps. They consume a lot of power. The ultimate realization of this would be like a big cat running across rough terrain. Each leg adjusts for the terrain at every touchdown of each foot. In contrast a damper just absorbs energy; Pushing a vehicle across rough terrain would be kinda like pushing it through treacle - the road undulations drive the dampers up and down which absorbs and wastes energy.
"Semi-active" systems can only absorb energy, such as dampers that change their damping curves in real-time. Various systems have various bandwidth (speed). Some are fast enough to react to the aftermath and oscillation after a bump, some can only change in half a second or so.
Here are some of the options
- active preload a la early 2000 Mercedes, and 1980s Williams F1 cars.
-- these change ride height to counteract body roll for corners or aero loads or changing passenger loads but aren't fast enough for reacting to bumps in real time. What this allows you to do is use soft springs so bump absorption is good. The coming Merc system will have a "look ahead" feature using video cameras to for example, raise the ride height and soften damping in anticipation of a speed bump, then stiffen the damping to damp oscillations afterwards.
- active swaybar preload, a la Porsche 991, 2006+ 750i, and 2008+ BMW sport suspension 5-series
-- these allow soft swaybars for good ride but wind-up (pre-load) for corners and work as part of the active stability control (My 750i is realllly good here, such as launching out of corners from a stop. It plants the rear tires, and general stability correction is very smooth)
- "automatic" adjustable dampers. Imagine Tein EDFC but which can decide on its own to stiffen up in < a second if it detects frisky driving or the push of a "sport" button. Early 2000 BMW "M sport" and other cars do this. Kinda lame if you ask me.
- MR dampers. These can change damping in 10s of milliseconds to improve ride and grip, so it will be well damped against body motions but soft to wheel motion from bumps. The damping forces can be changed over a wide continuous range. These are great.
- switching dampers. These are like a poor man's MR damper. But instead of a wide continuous range of damping curves available, it will switch between 2 or 3 presets. They are fast enough to kill oscillations after hitting bumps a certain way. Certain mid 2000 Jaguars had this for reacting to brake dive among other things. AFAIK the F430 does too. The ride quality improvement is substantial (I've driven one in anger extensively)
see beginnings of my blog Jason's engineering and other musings: Bi-state or Tri-state semi-active vehicle damping
- Audi has proposed electromagnetic dampers. The dampers instead of being fluid filled, will be a linear motor which can absorb energy which will be recycled to the perhaps-hybrid powertrain. This will have similar advantages to MR shocks, but with faster control bandwidth and some energy regeneration. Shocks won't get hot! They can also probably push or pull a wheel up actively, but I doubt they'll have enough oomph to match the prototype Bose system. This system will probably provide better performance than MR dampers.
The above bose system is "fully active" and "full bandwidth" (fast) in that each corners hydraulic ram (or other actuator) can both absorb or deliver energy (e.g. push a wheel down), in real time to react to bumps. They consume a lot of power. The ultimate realization of this would be like a big cat running across rough terrain. Each leg adjusts for the terrain at every touchdown of each foot. In contrast a damper just absorbs energy; Pushing a vehicle across rough terrain would be kinda like pushing it through treacle - the road undulations drive the dampers up and down which absorbs and wastes energy.
"Semi-active" systems can only absorb energy, such as dampers that change their damping curves in real-time. Various systems have various bandwidth (speed). Some are fast enough to react to the aftermath and oscillation after a bump, some can only change in half a second or so.
Here are some of the options
- active preload a la early 2000 Mercedes, and 1980s Williams F1 cars.
-- these change ride height to counteract body roll for corners or aero loads or changing passenger loads but aren't fast enough for reacting to bumps in real time. What this allows you to do is use soft springs so bump absorption is good. The coming Merc system will have a "look ahead" feature using video cameras to for example, raise the ride height and soften damping in anticipation of a speed bump, then stiffen the damping to damp oscillations afterwards.
- active swaybar preload, a la Porsche 991, 2006+ 750i, and 2008+ BMW sport suspension 5-series
-- these allow soft swaybars for good ride but wind-up (pre-load) for corners and work as part of the active stability control (My 750i is realllly good here, such as launching out of corners from a stop. It plants the rear tires, and general stability correction is very smooth)
- "automatic" adjustable dampers. Imagine Tein EDFC but which can decide on its own to stiffen up in < a second if it detects frisky driving or the push of a "sport" button. Early 2000 BMW "M sport" and other cars do this. Kinda lame if you ask me.
- MR dampers. These can change damping in 10s of milliseconds to improve ride and grip, so it will be well damped against body motions but soft to wheel motion from bumps. The damping forces can be changed over a wide continuous range. These are great.
- switching dampers. These are like a poor man's MR damper. But instead of a wide continuous range of damping curves available, it will switch between 2 or 3 presets. They are fast enough to kill oscillations after hitting bumps a certain way. Certain mid 2000 Jaguars had this for reacting to brake dive among other things. AFAIK the F430 does too. The ride quality improvement is substantial (I've driven one in anger extensively)
see beginnings of my blog Jason's engineering and other musings: Bi-state or Tri-state semi-active vehicle damping
- Audi has proposed electromagnetic dampers. The dampers instead of being fluid filled, will be a linear motor which can absorb energy which will be recycled to the perhaps-hybrid powertrain. This will have similar advantages to MR shocks, but with faster control bandwidth and some energy regeneration. Shocks won't get hot! They can also probably push or pull a wheel up actively, but I doubt they'll have enough oomph to match the prototype Bose system. This system will probably provide better performance than MR dampers.
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