v-Lockers. Let's poke a dead horse.

[Visket]

I thought I would get Tread Lightly's take on whether lockers save, or tear up the ground beneath us:

Me to TreadLightly.org:

/QUOTE:
I am hearing my fellow Jeepers arguments on both sides, including, but not limited to:

Pro-lockers: Less wheel spin on the technical areas = less damage.

Anti-lockers: Going around corners on fire roads tears up the corners unnecessarily.

What is the official stand of Tread Lightly?
/End QUOTE

TreadLightly.org to me:

/QUOTE
Mike, thanks for your question.

The points that you make are both valid.

I’m not a Jeep guy personally as I have a Bronco, but we do have a Tread Lightly! Gladiator. Me personally, I find myself switching them on and off multiple times during a ride for the exact reasons that you mention, both in the Bronco and Gladiator.

I don’t think lockers are right or wrong, or good or bad, it’s about using them when appropriate.

Trust that helps.
/End QUOTE

So Rivian... are you listening? I know wheel slip/spin is part of the traction algorithm, but according to the folks at TreadLightly, LESS wheel spin = less damage WHEN APPROPRIATE. In other words, if appropriate, use (old school, dumb) lockers. In other words, HAVE lockers available for use "when appropriate".

My only suggested enhancement to the current batch of "dumb" lockers would be to account for turning (the various distances of the paths each wheel takes in a turn radius) to run the motors at slightly different speeds.

It would add major chops to Rivian's off-road abilities - I think. I would be happy to be a "Beta" tester for you.

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[COdogman]

I know part of the reasoning for dumping tank turn was environmental damage, but I was not aware this was a consideration when it comes to locker/ no locker? I thought they just felt their design was good and didn't need lockers...

 

[Visket]

I know part of the reasoning for dumping tank turn was environmental damage, but I was not aware this was a consideration when it comes to locker/ no locker? I thought they just felt their design was good and didn't need lockers...

The current is "good". Do we settle for "good", when "better" and "best" are a few lines of code away?

From what I have read, the traction algorithm requires some wheel slippage to determine the type of terrain and traction available at any given moment - for each wheel. No slippage, no determination. (Hey Rivian - please correct me if I am off-base here!).

From many YouTube (R) videos, and a few of my own situations (I also have a built Jeep TJ, an overlanding Tacoma and a 4Runner TDR Pro), I can tell Rivian that some Good Old Skuul, albeit virtual, lockers - with turning algorithms! - would be, in technical terms, Da Bomb.

Slow and easy (adjustable speed from .1 - 5-ish mph), yet forceful (full torque), with a full, regulated hard stop (regen + brakes and no backing up!) when the go-pedal is released. One pedal rock crawling, eh?

 

[mikehmb]

I’m willing to bet that they do not go full-locker because their current implementation significantly reduces stress on components while being Very Good off-road (to your point, could be Great with it). Though like you, I would like them very much

I can easily imagine an off-road novice go to full-locker mode when it’s entirely inappropriate, because it’s simply a button tap away.

 

[COdogman]

The current is "good". Do we settle for "good", when "better" and "best" are a few lines of code away?

From what I have read, the traction algorithm requires some wheel slippage to determine the type of terrain and traction available at any given moment - for each wheel. No slippage, no determination. (Hey Rivian - please correct me if I am off-base here!).

From many YouTube (R) videos, and a few of my own situations (I also have a built Jeep TJ, an overlanding Tacoma and a 4Runner TDR Pro), I can tell Rivian that some Good Old Skuul, albeit virtual, lockers - with turning algorithms! - would be, in technical terms, Da Bomb.

Slow and easy (adjustable speed from .1 - 5-ish mph), yet forceful (full torque), with a full, regulated hard stop (regen + brakes and no backing up!) when the go-pedal is released. One pedal rock crawling, eh?

I traded in a Tacoma TRD Pro for my R1T so I definitely appreciate having lockers. I haven't had much time to go off roading since I picked up my Rivian but I think the consensus here from experienced off roaders is that lockers would be a welcome upgrade.

I tend to agree with @mikehmb and assume Rivian has a secondary reason for not adding it. Plus, the majority of owners will likely never need it so maybe that is a factor also.

 

[ndmiller]

Dead horse not stirring. It's a niche customer group in a niche small production vehicle. One day, but not for a long while, they have too many fish to fry and are a public company so shareholders to please. Maybe a software option before hardware.......

 

[k3g]

I would love something similar in results to a locker: I want less wheel speed and more controllable torque delivery when unweighting wheels and crawling up stuff.

I don't care if they make it a locker (velocity control of rear wheels regardless of perceived "differential slip") or just add a crawl control mode, I'd like better crawling capability.

 

[KootenayEV]

I wonder if they could add more ‘poles’ to the wheel speed sensors to get better resolution on when a wheel is slipping? I haven’t seen details on the current implementation.

edit: eg if they only have 4 poles, the wheel needs to rotate as much as 90 degrees to provide the next input to the software.

 

[Visket]

I wonder if they could add more ‘poles’ to the wheel speed sensors to get better resolution on when a wheel is slipping? I haven’t seen details on the current implementation.

edit: eg if they only have 4 poles, the wheel needs to rotate as much as 90 degrees to provide the next input to the software.

I'm thinking they don't need sensors on the wheels - each motor has a gear reduction box ratio of somewhere around 12.6:1 (motor:wheel), so 1 motor rev = 30 degrees of wheel.

In any event, have the software ignore the slippage, and "simply" turn each motor at full torque at the crawl speed specified by the driver (outside wheels slightly faster, of course).

I agree with the opinions of other fish to fry, niches, shareholders, etc... but we might be showing Rivian special interest in this by continuing to post and respond to threads such as this.

Plus, since TreadLightly has opined that "lockers" (I'm betting virtual or mechanical) spin/slip less, they are better for the environment. Let's see how dedicated Rivian is to that!

 

[dgennetten]

I, for one, am silently hoping for some pleasant surprises in the off-roading capabilities (upgrades) of the R2.

This would be an excellent area of exploration, combined with the per-wheel gearboxes that Rivian has patented (link?)

 

[COdogman]

I, for one, am silently hoping for some pleasant surprises in the off-roading capabilities (upgrades) of the R2.

This would be an excellent area of exploration, combined with the per-wheel gearboxes that Rivian has patented (link?)

https://jalopnik.com/rivian-patents-a-low-range-gearbox-for-electric-off-roa-1850090533

 

[KootenayEV]

I'm thinking they don't need sensors on the wheels - each motor has a gear reduction box ratio of somewhere around 12.6:1 (motor:wheel), so 1 motor rev = 30 degrees of wheel.

In any event, have the software ignore the slippage, and "simply" turn each motor at full torque at the crawl speed specified by the driver (outside wheels slightly faster, of course).

I agree with the opinions of other fish to fry, niches, shareholders, etc... but we might be showing Rivian special interest in this by continuing to post and respond to threads such as this.

Plus, since TreadLightly has opined that "lockers" (I'm betting virtual or mechanical) spin/slip less, they are better for the environment. Let's see how dedicated Rivian is to that!

To discern a motor revolution they still need sensors in the motor; 30 degrees is a lot, so hopefully they have more poles inside.

AFAIK, you would need the feedback from the sensors to discern how fast to rotate the wheel; if you apply too much torque it is going to spin; ergo you can't do the "simply turn each motor ... at crawl speed specified by driver" without the sensor to close the control loop for the motor torque.

 

[Visket]

To discern a motor revolution they still need sensors in the motor; 30 degrees is a lot, so hopefully they have more poles inside.

AFAIK, you would need the feedback from the sensors to discern how fast to rotate the wheel; if you apply too much torque it is going to spin; ergo you can't do the "simply turn each motor ... at crawl speed specified by driver" without the sensor to close the control loop for the motor torque.

I agree with that - mostly.

I was speculating that each motor has *at least* one (at minimum, before the gear reduction box) sensor in it.

Worst case scenario: One motor sensor on 34" Tires (on the ATs) = (34 * 3.1416 = 106.8144" (circumference) / 12.6 (gear reduction box) = 1 sample per every 8.47 inches of roll. That's with one sensor per motor.

My point is that with the ability to traction control snow, street, sand, etc..., I am speculating that no more hardware is needed (hopefully!). Two sensors = 4.235" granularity, etc...

Oh - I wanted to also comment on the "abuse" the drivetrain may take. Each axle needs only take the abuse of the 200hp motor turning it. It isn't like an ICE / driveshaft / differential / axle that would be called upon to take the hit of the entire engine HP when the tire suddenly grabs (and breaks axles, etc..). The Rivian can withstand 0-60mph blasts all day long with the axles it has (again, speculation..), so I'm confident in my R1T to withstand some grappling at 1mph over some rocks.

And as far as novice or inexperienced drivers - meh. Get a Prius.

 

[HaveBlue]

Hyundai reinvented a kinder gentler tank turn.

 

[UnsungZero_OldTimeAdMan]

Hyundai reinvented a kinder gentler tank turn.

More complexity. More failure points. Especially for vehicles that may get driven on challenging and remote trails. Rivian’s tie-rods are already suspect for some, imagine what this could mean to durability of suspension and driveshafts.

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