S-AWC and Regen etc.

[Trex]

Hi folks,

Been asked by dogman12 this in another topic:

Phevy, Trex: I've had a lot of very slick roads to deal with this winter. I have been wondering about the allocation of Regen. With the S-AWC (which is overall excellent,) is Regen equal on all four wheels, all the time, or allocated depending on traction/slippage?

And, will S-AWC do anything in B-0 while coasting if slippage occurs? Asking for a friend

Hi dogman12,

So we are talking about S-AWC and Regen. Lets deal with S-AWC and what it is which according to Wikipedia:

"S-AWC (Super All Wheel Control) is the brand name of an advanced full-time four-wheel drive system developed by Mitsubishi Motors. The technology, specifically developed for the new 2007 Lancer Evolution, the 2010 Outlander (if equipped), the 2014 Outlander (if equipped), the Outlander PHEV and the Eclipse Cross have an advanced version of Mitsubishi Motors' AWC system."


This according to Mitsubishi:


"S-AWC used in Outlander PHEV has the integrated control function of Twin Motor 4WD and AYC which controls the driving force distribution between front and rear wheels and between right and left wheels."


Now we better deal with some more definitions. Mitsubishi state for Twin Motor 4WD :


"TWIN Motor 4WD controls the driving torque and the regenerative braking torque by front and rear electric-motors respectively."


So this system ie TWIN Motor 4WD is controlled by the electric motors/generators on the front and back axles. Notice dogman12, Regen already get a mention.

For AYC (Active Yaw Control) Mitsubishi state:


"AYC controls braking force for each wheel respectively. Moreover, ABS (Anti-lock braking system) and ASC (Active Stability Control) is controlled optimally."


So basically this system ie AYC (Active Yaw Control) is controlled by the physical disk brake on each wheel.

Now Mitsubishi also state for S-AWC (Super All Wheel Control) :


"S-AWC achieves a faithful handling to the driver's operation and enhanced stability, and supports the driver safety, the comfortable vehicle characteristic and the efficient vehicle driving.

Driver can select two operating mode by 4WD LOCK switch: "NORMAL" is for usual use and "4WD LOCK" is for higher traction ability."


Now from all of the above we have 2 systems ie TWIN Motor 4WD and AYC (Active Yaw Control) integrated (integrated, meaning linked or coordinated) so in answer to your question "is Regen equal on all four wheels, all the time, or allocated depending on traction/slippage?" we need to remember we only have two electric motors/generators ie one for the front two wheels and another for the back two wheels. So if one wheel on one axle started slipping the PHEV would need to reduce Regen on that axle and then could use the physical individual disk brakes to compensate for that loss of Regen braking on that axle or even just reduce the Regen a little till no slippage occurs like with ABS brake control.

Now as Mitsubishi have already stated above that "TWIN Motor 4WD controls the driving torque and the regenerative braking torque by front and rear electric-motors respectively." which mentions Regen specifically I think this answers your first question.

Now for your 2nd question "And, will S-AWC do anything in B-0 while coasting if slippage occurs?" I think the AYC (Active Yaw Control) which includes ABS (Anti-lock braking system) and ASC (Active Stability Control) part of the S-AWC (Super All Wheel Control) system would probably come more into play although the TWIN Motor 4WD system could still be part of this scenario I could imagine.

Hope this helps and please ask questions if I have not explained myself good enough. I think I can be a little rushed in my reply's sometimes.

Regards Trex.

 

[Trex]

S-AWC images from Mitsubishi Motors

 

[dogman12]

Awesome research, thanks! I am clear on everything but what the various systems might do when coasting: no power being applied. IE - B-0 down a slight hill with a curve. The vehicle starts to slide to the outside a bit. Would Yaw or Stability kick in? Or what? I realize this is a rather obscure situation, that doesn't lend itself to the "marketing speak" descriptions of the systems. thanks again.

 

[karl]

The stability system activates in all modes : braking, generative braking, coasting, or accelerating. The manual "disable" button disables some features, like anti-spin, and maybe dials down the other bits, but it's not totally disabled.

The yaw-control system is easy to notice, just wiggle the steering wheel and listen to the rattling brakes.
The ABS system will probably reduce the regen if it detects a locked wheel, but I think you need pretty bad tires or a really steep and icy hill to for this to happen because of regen only.

 

[dogman12]

 

[Trex]

Added some images above to hopefully help explain what S-AWC can do.

 

[ThudnBlundr]

The car can't "demand" a set regen level come what may, but has to accept what is available. Don't forget that regen is powered by the electric motors (acting as generators) resisting the torque in the driveshaft produced by the wheels turning, and so the torque of the turning wheels actually powers the regen. If a wheel starts slipping for whatever reason, by definition it means that the torque produced by that wheel has been reduced. So to a great extent, the regen is self-limiting in slippery conditions, and will simply drop without any intervention by the electronics when a wheel slips.

What the electronics do when it detects wheel slip is a bit of a black box from then on...

 

[dogman12]

Trex: thanks again.

My steep 250 feet of driveway got a deep load of very wet snow this week. In 4Lock the PHEV didn't do very well. It seemed to me (from the same situation in a dumb 4WD Jeep previously) that anti-slip was NOT doing as much, or anything. It kept digging and thus slid toward the down side, where even deeper snow was. I only made it up by taking the 4Lock Off. There was obviously slip control then. The vehicle moved forward, accelerating lightly, until it hit deeper mush. I left my go pedal in the same position, and the power to the wheels was reduced, vehicle slowed, until it got better traction, then accelerated again. This cycle happened about 4 times get all the way up.

So I suppose there is a way to reconcile that with the Mitsu description above. We don't need to belabor the issue, I know what settings to use when, better now after this discussion.

 

[ThudnBlundr]

Maybe this video will help explain why it doesn't work as expected. It's quite long-winded, but does propose some theories...

https://www.youtube.com/watch?v=KnUxphPSjdI

 

[jaapv]

In this situation you have to switch the stability control off. RTM.
And use winter tyres.

 

[dogman12]

jaapv: So you are saying 4Lock On, Stability Off?

I have new excellent winter tires.

 

[jaapv]

Yes. Otherwise it will dig itself in by applying more and more wheel braking.