ajdelange

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Id be curious to know which drive mode he was in and what the regen brake settings were. From other reviews, I've seen people stopped on descents I believe without having their foot on the brake. I'd imagine it would also allow for hill hold with max regen on. Or perhaps the weight and grade of the hill were more than the regen could.
Regen doesn't take place unless the vehicle is in motion so hill hold by regen is impossible. Yes, you can lock the rotors electrically but it takes stator current and that would waste energy.
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0===0Riv

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Both of his vids, nothing on actual range (on or off road) or charge speed? guess i truly have to wait on one of you to get your truck for that info
 

Canthoney

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If it’s worth anything, I was told back in September at the 1st mile event that the tire pressure monitoring system would include individual tire monitors like most new cars with tech packages. So I think it’s just literally a software update forthcoming
 

godfodder0901

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But if you read the words in the manual that say "This vehicle is equipped with a Tire Pressure Monitoring System (TPMS) with individual tire pressure display", then you would think you'd get a display on an individual tire basis.
I agree 100% that it should have that feature, but the fact that no one has seen it and the manual has an alarming level of ambiguity (and specifically mentions the telltale indicator as seen below) makes me think there is a chance we don't get the individual tire pressure display.
 

jjswan33

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For what its worth on the TPMS sensors. The sensors at each wheel will absolutely be able to give the tire pressure at that tire, whether the software displays it is another matter all together.

As an example my ProMaster has individual TPMS sensors in each wheel but the factory computer just gives a warning when any one of them is below recommended pressure (65psi in front, 80psi in the rear, 80psi in the spare). When I updated the head unit in my ProMaster with one that connects with a Maestro unit. With the new unit I can turn on a display to get the tire pressure of all the tires as well as check any engine codes etc.

So this should definitely be a software update IMO. That is assuming that Rivian will listen to what customers want.
 

Dark-Fx

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That's kind of what I think they are trying to do. But what happens when a tire slips on you? Your frictional resistance drops and that tire has to restrain itself after the fact, while assuming the other tire is correct. there's a great jalapnik video from David avy about this. Without another special sauce mixed in, that's likely a limitation of 4 independent motors.
They should just be able to cut power basically instantly when there is a sudden unexpected increase in RPM that's not corroborated with the other tires. Running some second order derivative (jerk) filtering against the values should be able to determine that on a single wheel. It does look like they might be doing this with their traction control, but it doesn't react as quick as I'd expect it to. Likely just another thing that needs more tuning.
 

SeaGeo

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They should just be able to cut power basically instantly when there is a sudden unexpected increase in RPM that's not corroborated with the other tires. Running some second order derivative (jerk) filtering against the values should be able to determine that on a single wheel. It does look like they might be doing this with their traction control, but it doesn't react as quick as I'd expect it to. Likely just another thing that needs more tuning.
Have you had a chance to read what Rivian told David about it? Watching Doug's experience, the response definitely seemed different (and less controlled) than what I recall seeing from the Colorado drives or other informal climbing videos people have taken. I am a little curious if Doug just didn't have the right drive mode selected.

For reference (because I think it's interesting) I've added the excerpt I was referencing.

https://jalopnik.com/a-ridiculously-detailed-look-at-why-the-rivian-r1t-elec-1847749837

“I wanna say our [refresh rate] is 100hz in the inverter” he said. “Basically our torque command can change let’s say on the order of 100hz. 100 times per second you can say ‘Am I going too fast, too slow.’”

Verbridge said the R1T’s four-wheel drive system isn’t meant to simulate a locker. “But basically where you set your slip target defines how close to [a locker] you are. Slip targets are surface dependent — what the vehicle expects the mu [friction coefficient] to be will change how much we allow the wheel to slip above whatever we think is vehicle reference speed.”

“That does get tricky... if all four wheels are spinning, what is vehicle reference? GPS can help you a little bit, but you don’t know how fast is the ground moving beneath me, right?” he continued. “But in the case of one wheel we generally have a good idea from the other three how fast is the vehicle actually going, and we can keep that slip within check.”

Think about that for a second. Rivian’s system has to not only predict the friction coefficient (which is constantly changing!) but it also has to figure out what the vehicle’s speed is, which isn’t easy to do if there’s slip at all corners.

Verbridge admits there are limitations to the system. “There’s a PID gain loop there... a control reaction time iteration time in your way,” he said. “To your point, it’s not gonna be perfect. How quickly can you go ‘I’m slipping. Stop.’ That’s your limit of the technology.” He notes that the system is quick, but admits that the wheels do flare up a “quarter turn at a time” before the control software brings the wheel speed down.
 

Dark-Fx

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Have you had a chance to read what Rivian told David about it? Watching Doug's experience, the response definitely seemed different (and less controlled) than what I recall seeing from the Colorado drives or other informal climbing videos people have taken. I am a little curious if Doug just didn't have the right drive mode selected.
This wouldn't surprise me at all and would explain the apparent lack of descent control, among other things.
 

dleewla

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Regen doesn't take place unless the vehicle is in motion so hill hold by regen is impossible. Yes, you can lock the rotors electrically but it takes stator current and that would waste energy.
its not impossible (either by regen or physical brakes). its been demonstrated by folks who test drove the vehicle. they've stated the car was not moving on a hill, even though they had their foot of the accelerator.
 

dleewla

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Have you had a chance to read what Rivian told David about it? Watching Doug's experience, the response definitely seemed different (and less controlled) than what I recall seeing from the Colorado drives or other informal climbing videos people have taken. I am a little curious if Doug just didn't have the right drive mode selected.

For reference (because I think it's interesting) I've added the excerpt I was referencing.

https://jalopnik.com/a-ridiculously-detailed-look-at-why-the-rivian-r1t-elec-1847749837

“I wanna say our [refresh rate] is 100hz in the inverter” he said. “Basically our torque command can change let’s say on the order of 100hz. 100 times per second you can say ‘Am I going too fast, too slow.’”

Verbridge said the R1T’s four-wheel drive system isn’t meant to simulate a locker. “But basically where you set your slip target defines how close to [a locker] you are. Slip targets are surface dependent — what the vehicle expects the mu [friction coefficient] to be will change how much we allow the wheel to slip above whatever we think is vehicle reference speed.”

“That does get tricky... if all four wheels are spinning, what is vehicle reference? GPS can help you a little bit, but you don’t know how fast is the ground moving beneath me, right?” he continued. “But in the case of one wheel we generally have a good idea from the other three how fast is the vehicle actually going, and we can keep that slip within check.”

Think about that for a second. Rivian’s system has to not only predict the friction coefficient (which is constantly changing!) but it also has to figure out what the vehicle’s speed is, which isn’t easy to do if there’s slip at all corners.

Verbridge admits there are limitations to the system. “There’s a PID gain loop there... a control reaction time iteration time in your way,” he said. “To your point, it’s not gonna be perfect. How quickly can you go ‘I’m slipping. Stop.’ That’s your limit of the technology.” He notes that the system is quick, but admits that the wheels do flare up a “quarter turn at a time” before the control software brings the wheel speed down.
Pros and cons of 4 wheel drive / torque vectoring and lockers. sounds like advantages for one in some scenarios while disadvantage for the other. im sure they weighed the compromises and decided it was more benefits to go 4 motors. and my guess it it'll only get better with time as the system learns and optimizes.

which means we need to get more vehicles in the hands of customers to build up thier data set. which means early deliveries next year will continue to be "test" vehicles . honestly, all vehicles will continue to be test vehicles but i guess thats just the nature of software and software based systems. h/w requires much more finalized choices while s/w leave a lot of wiggle room(and room for bugs... ahem... features).
 

ajdelange

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its not impossible (either by regen or physical brakes). its been demonstrated by folks who test drove the vehicle.
It's not being done by regen. I have not had the pleasure of driving (or even laying eyes upon) a Rivian so I can't be certain but it is probably done by "blending" as is done in the Teslas. When the rotor speed gets low the "back emf" approaches 0 and trickery is necessary to boost it to the point where it is greater than (and can, thus, charge) the battery but you aren't getting much at this point and so as they roll regen out with decreasing speed they roll friction brake in. When the car is completely stopped it is being held by the friction brake alone. The power meter reads 0. This makes one pedal driving possible even when stopped on a hill and taking the regen down to close to 0 supposedly adds a couple of miles to the the Teslas' EPA range.
 

CO_R1S

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“I wanna say our [refresh rate] is 100hz in the inverter” he said. “Basically our torque command can change let’s say on the order of 100hz. 100 times per second you can say ‘Am I going too fast, too slow.’”

Verbridge said the R1T’s four-wheel drive system isn’t meant to simulate a locker. “But basically where you set your slip target defines how close to [a locker] you are. Slip targets are surface dependent — what the vehicle expects the mu [friction coefficient] to be will change how much we allow the wheel to slip above whatever we think is vehicle reference speed.”
I have no doubt that over time this technology could get very good, especially if they link conditions to location, etc.

In the meantime, an old school drive mode of “turn all motors at a fixed rate” would be beneficial as off-roading people make the transition to this technology. The video of the R1T ascending hells gate looked awkward because it appeared the (very experienced) driver could not precisely predict what the vehicle was going to do… At least with all wheels rotating at a constant rate you would have a better seat of the pants understanding what the vehicle is doing.
 

Blueassassin

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I have no doubt that over time this technology could get very good, especially if they link conditions to location, etc.

In the meantime, an old school drive mode of “turn all motors at a fixed rate” would be beneficial as off-roading people make the transition to this technology. The video of the R1T ascending hells gate looked awkward because it appeared the (very experienced) driver could not precisely predict what the vehicle was going to do… At least with all wheels rotating at a constant rate you would have a better seat of the pants understanding what the vehicle is doing.
I agree but the terrain in a lot of locations changes every time it rains. The fixed rate for all four tires "locked up" would be great. As someone mentioned already it wouldn't be that easy unfortunately. But this is guaranteed to be a lot of the over the air updates coming is working on the traction control and dynamics. imagine crawl control from Toyota but it being able to control every wheel and every brake.
 
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