Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Ford F-150 Lightning Breezes Up Obstacle Where Tesla Cybertruck Struggled

thedrive.com

Post reply on HN
Print view View original

71–80 of 93 posts

Re: Ford F-150 Lightning Breezes Up Obstacle Where Tesla Cybertruck Struggled

#71

Post by whalesalad »

gavin_gee wrote: post #45

All these comments about a lack of locking diff on the CT could be the reason but it seems that this capability can be achieved in software with motors on all 4 wheels. - you don't allow the motor/wheel to move at a different speed to another on the same axle. Therefore this, to me at least, seems like an easy pathway for improvement for the CT. And we have already seen, telsa has the best software team with companie…

I was with you until you said Tesla has a killer software team.

This is going to be a test for them. They’re always on, digital, networked, touchscreen-powered ethos is going to fall apart with the truck and off road. Stuff is physical in a truck because you’re often wearing gloves and operating in rough environments.

But seriously - we need to all ack here that this is not a truck. It looks like a truck, yes, but it does not walk or quack like one. Do a lot of current truck owners use them as a fashion statement? Yes. But on the flip side a lot of truck owners do truck things and the cyber truck won’t compete there. As a fashion accessory/commuter/bulletproof SF tenderloin machine yes it will and I actually think it looks pretty cool.

Re: Ford F-150 Lightning Breezes Up Obstacle Where Tesla Cybertruck Struggled

#72

Post by SigmundA »

deelowe wrote: post #31
SigmundA wrote: post #25

Earlier quoted context omitted.

It's not about turning at the same pace, the side that has no traction cannot send its torque to the side that does without a mechanical connection. Each wheel is limited to the maximum torque of a single motor vs torque being sent to all wheels in a traditional single ICE engine with transfer case and lockers. You can see a quad motor Rivian performing worse than the new dual motor due this issue, the dual motor can…

You just need motors large enough to break traction. After that, it's irrelevant. Doesn't seem impossible to me.

Yeah just need larger motors that can put out more torque which adds more cost and weight. Or you can have a way to connect each side with a locker or a single larger motor with brake locker control like dual motor vs quad motor Rivian's. Again the quad motor Rivian can be stalled on rock crawling due to lack of torque when multiple wheels lose traction.

Electric motors have a lot of torque but EV drive trains are usually single speed so it must not have too much gear reduction for highway speed. A modern ICE offroad vehicle has a multispeed transmission with torque converter that greatly amplifies stall torque along with a transfer case that has a low range that multiplies even further. I would imagine when jeep does an electric production Wrangler it will probably have dual motors with lockers and may even have a 2 speed transmission for low range. Maybe they will even do like their Magento prototype and run a single large electric motor through a traditional transfer case and driveline.

Re: Ford F-150 Lightning Breezes Up Obstacle Where Tesla Cybertruck Struggled

#73

Post by bb88 »

Some poor engineer in Tesla probably tried to raise this issue and got shut out of meetings. And it was probably the kind of engineer that actually cared about traction control performance. And he also probably wanted to further the Tesla brand.

But Elon is so busy these days managing 3 companies, that he just should quit two of them now.

If I have the choice, today I'm choosing the F-150 lightning.

Re: Ford F-150 Lightning Breezes Up Obstacle Where Tesla Cybertruck Struggled

#74

Post by mike_d »

brucethemoose2 wrote: post #67
giobox wrote: post #62

Earlier quoted context omitted.

It's not yet clear virtual locking diffs on quad motor cars will be as effective as a fully locked diff. A software system will likely have to detect some small degree of slip before intervening to sync the wheel speed again - that slip just wouldn't occur in the first place on a fully locked setup given its impossible for one wheel to spin faster than the other. This seems to be the experience of Rivian owners who h…

That's a solvable software problem. The electric motors know how much they are spinning, they just need to be modulated quickly enough and intelligently enough.

Motors know nothing. The encoders know how much current is being input to the motor, but do not know the rotational output of the motor or the friction coefficient between the tires and the ground. All three are things you'd need to emulate a locking differential in software. You could fake the last two by having a reliable way to measure the travel of the vehicle from a source other than the wheels (GPS, downward camera, etc).

Re: Ford F-150 Lightning Breezes Up Obstacle Where Tesla Cybertruck Struggled

#75

Post by SigmundA »

giobox wrote: post #46
lolbase wrote: post #16

For context, this is a video of a traditional truck driving up the same hill: https://www.youtube.com/watch?v=ptTwpkWQY_s And here's a Range Rover going up it: https://www.youtube.com/shorts/_00ah8lG4yk It seems like the CT doesn't have the equivalent of a locking diff, and had essentially no articulation. It'll be fine for the target demo (on-road usage). Both the Lightning and the CT clearly suffer from their weigh…

I wonder if the tri-motor CT models will be able to simulate a locked rear diff, much like the quad motor rivian models can simulate a locked diff front and rear thanks to being able to adjust torque to all four wheels individually. Only the rear axle of the CT would presumably be able to do this due to the tri-motor layout, unless they resort to the individual wheel braking like they've done on their road cars to si…

I posted below but you cannot fully simulate a locker with independent motors. The quad motor Rivian is actually inferior to the dual motor for rock crawling due to this.

The quad motor Rivian produces 908 lbs/ft of torque which means each motor produces 908/4 = 227 lbs/ft. It has a single speed gear ratio of 12.6:1 meaning each wheel can get a maximum of 227 * 12.6 = 2860.2 lbs/ft wheel torque.

The dual motor Rivian produces 829 lbs/ft of torque which means each motor produces 829/2 = 414.5 lbs/ft. It has has a single speed gear ratio of 13.7:1 (11:1 front) in the rear meaning each rear wheel can get a maximum of 414.5 * 13.7 = 5678.65 lbs/ft wheel torque (4559.5 front) with brake locking diff.

Contrast this with a Jeep Wrangler which can put out 20,000 to 30,000 lbs/ft of torque to any single wheel through its torque converter, transmission, transfer case and axle gearing which can be over 100:1 in gear ratio and single ICE.

There are videos of Rivian's stalling rock crawling that are no issue for an old Jeep with weak engine due to lack of torque to the wheels. EV's will need lockers and probably at least two speed transmission to compete here, or they will need way oversized quad motors to make enough low speed torque without the gearing and lockers.

Re: Ford F-150 Lightning Breezes Up Obstacle Where Tesla Cybertruck Struggled

#76

Post by mike_d »

whalesalad wrote: post #32

Honestly both are abysmal. Even the F-150 is slipping like crazy in areas where it shouldn't matter. Locking differentials are really required for this sort of thing - or a four wheel motor setup where a motor is dedicated to each wheel and can apply power equally. Afaik none of the EV trucks have a mechanical locker or even a limited slip? This might be as easy as a software update for both. Reducing tire pressures…

> No one is gonna be doing this sort of thing with an EV though. There is no charging infrastructure out in the boonies.

Jeep has built solar supplied charging stations at most of the 56 badge of honor trailheads and continues to expand in partnership with Volkswagen. The Rivian recently did an end-to-end run of the Rubicon trail using the Jeep chargers.

Re: Ford F-150 Lightning Breezes Up Obstacle Where Tesla Cybertruck Struggled

#77

Post by SigmundA »

jmtulloss wrote: post #65
SigmundA wrote: post #10

Looks like the Tesla has an open diff with poor brake lock diff control, I think the lighting has an option for a locking rear diff wonder if they were using it, looks like it. Interesting thing about the Rivian quad motor version is while it has full software control due to a motor per wheel, this can be a downside for crawling like this because it has no way to send torque from one side to the other, so if say only…

I am no expert at this but I think the Rivian should perform comparably. The Rivian can do 908 lb-ft of torque. Like you say, that's divided up amongst the 4 wheels, so that's 227 lb-ft per wheel. The Jeep can do 260 lb-ft total. The Rivian weighs ~7200 lbs and the Jeep weighs ~5300 lbs. So, with only one wheel of traction you're right. If you can transfer all of that torque on the jeep with less than ~14% loss (whic…

A Jeep can have over 100:1 gear ratio in low range with torque converter and transmission and axles, its can put 20,000 to 30,000 lbs/ft to the wheels a quad motor Rivian is a fixed 12.6:1 gear ratio so 11440.8 lbs/ft to the wheels max.

Now have two wheels lose traction and you cut that down to 5720.4 lbs/ft at the wheels while a Jeep with lockers put the full 20k+ torque to any one wheel as needed.

Re: Ford F-150 Lightning Breezes Up Obstacle Where Tesla Cybertruck Struggled

#78

Post by fragmede »

jmtulloss wrote: post #49
whalesalad wrote: post #32

Honestly both are abysmal. Even the F-150 is slipping like crazy in areas where it shouldn't matter. Locking differentials are really required for this sort of thing - or a four wheel motor setup where a motor is dedicated to each wheel and can apply power equally. Afaik none of the EV trucks have a mechanical locker or even a limited slip? This might be as easy as a software update for both. Reducing tire pressures…

I do things like this from time to time with my Rivian. You're right that charging infrastructure is a challenge, but two things make a big difference: - Lots of campgrounds have 30 or 50 amp plugs for RVs. Oftentimes off-road trips I go on start by everybody getting together at night so we can get an early start the next day. If you can meet near an RV campground (not always a great option), you can charge - Most of…

it's a truck. throw a honda genny with a 240v output, and a couple of gallons of gas, and charge it overnight. it's not about being perfectly environment pious, but going away from rolling coal.

Re: Ford F-150 Lightning Breezes Up Obstacle Where Tesla Cybertruck Struggled

#79

Post by 10u152 »

mike_d wrote: post #74
brucethemoose2 wrote: post #67

Earlier quoted context omitted.

That's a solvable software problem. The electric motors know how much they are spinning, they just need to be modulated quickly enough and intelligently enough.

Motors know nothing. The encoders know how much current is being input to the motor, but do not know the rotational output of the motor or the friction coefficient between the tires and the ground. All three are things you'd need to emulate a locking differential in software. You could fake the last two by having a reliable way to measure the travel of the vehicle from a source other than the wheels (GPS, downward ca…

Err, sorry but the encoders don't measure current. An absolute position encoder knows the exact speed/position of the motor. By that you can extrapolate the wheel speed position which you can just match 1:1 with the one on the other side. It won't be perfect as the reaction time of the system if wheel A breaks away and starts spinning but you don't need GPS or a downward camera to mimic a locking diff.

Re: Ford F-150 Lightning Breezes Up Obstacle Where Tesla Cybertruck Struggled

#80

Post by dreamcompiler »

jmtulloss wrote: post #49
whalesalad wrote: post #32

Honestly both are abysmal. Even the F-150 is slipping like crazy in areas where it shouldn't matter. Locking differentials are really required for this sort of thing - or a four wheel motor setup where a motor is dedicated to each wheel and can apply power equally. Afaik none of the EV trucks have a mechanical locker or even a limited slip? This might be as easy as a software update for both. Reducing tire pressures…

I do things like this from time to time with my Rivian. You're right that charging infrastructure is a challenge, but two things make a big difference: - Lots of campgrounds have 30 or 50 amp plugs for RVs. Oftentimes off-road trips I go on start by everybody getting together at night so we can get an early start the next day. If you can meet near an RV campground (not always a great option), you can charge - Most of…

Confirmed about the RV campgrounds. Almost every private RV campground has 50A service, and most state and national parks have 30A service. Both are sufficient to recharge a Tesla overnight, and the Model Y is big enough to sleep inside. I do it all the time.
Post reply on HN