Autopilot dangerously reducing speed on highways

[Fresnel]

That is totally understandable. Two things here that can avoid this dangerous situation:
1. Let the car move with the speed that was set to in AP (65, 70 mph etc..) without interfering with posted speed and this should be controlled by the driver not posted speed in maps
2. There should be a setting in AP that can give us options a) you want to follow the speed as per maps b) manually control the speed in AP.

True but manually setting a speed like that would negate the very important lowering speed when going around a bendy offramp. Where if It didn't automatically change the speed you might slide right off the road.

 

[Kennymb5384]

Mine always does this in the same place. On the freeway, but I noticed it is always in the same exact spot, and I believe it is due to there being a carpool exit on the left, and not on the right side where 95% of exits on the freeway are.

 

[Fresnel]

I'm sure they've known about this problem for a very long time (over reliance on maps), we just have no visibility to how they are planning to address it. There really isn't much of a financial incentive for them to devote resources to fixing it in the near future. They are likely focusing on features that can be released as FSD revenue. The whole business model is based on pushing out partially working software (typical of a tech company).

A lot of "buggy" (even though it's not a TACC bug, more like an overall flaw in the driver assistance system) features generates more revenue than chasing down all the problematic parts of existing feature sets.

We're all waiting for the pot of gold at the end of the HW3 rainbow.

Plus another nice thing with the "Beta" label is that it allows you to take less responsibility for when things do glitch. Even if they work nicely 90% of the time.

 

[Fresnel]

they could also put in an "anti brake-check" algorithm to the automatic speed change subsystem that would cap the amount of braking force/deceleration based on the distance of the car behind. This is called "anti-jerk" logic in conventional ICE vehicles, often used to cap jarring behavior on acceleration.

I like that idea a lot. It's like dynamic cruise control but it works with the car behind you instead of in front

 

[Knightshade]

FWIW when someone actually measured this "massive dangerous" braking it was like 0.2g

Which isn't really massive or dangerous at all-- it's about what regen gives you without even touching the brake pedal.

It just FEELS like a lot because you're not expecting it.

This is similar to how you, slamming the accelerator, enjoys the acceleration- while a passenger who was looking down at their phone and (lacking ICE noise/revving) had no idea it was coming and gets upset by it.

 

[CrayZ1]

yes and there should also be a feature to completely turn off TACC and run dumb cruise control sometimes for especially problematic situations like this.

they could also put in an "anti brake-check" algorithm to the automatic speed change subsystem that would cap the amount of braking force/deceleration based on the distance of the car behind. This is called "anti-jerk" logic in conventional ICE vehicles, often used to cap jarring behavior on acceleration.

This is what some EV ACC systems do: If somebody changes lanes into your frontal buffer zone, it will slowly reduce speed unless a collision is imminent. This applies to at least 4 EVs I can think of, and several ICE cars. I've not tested it in the Teslas yet. In fact, I have only used the TACC in fairly uncrowded situations.

 

[arghx7]

FWIW when someone actually measured this "massive dangerous" braking it was like 0.2g

Which isn't really massive or dangerous at all-- it's about what regen gives you without even touching the brake pedal.

It just FEELS like a lot because you're not expecting it.

This is similar to how you, slamming the accelerator, enjoys the acceleration- while a passenger who was looking down at their phone and (lacking ICE noise/revving) had no idea it was coming and gets upset by it.

There are two aspects. One is the comfort of the people in the car, which is going to be sensitive to sudden G forces, and the other is the car behind you which is going to be upset by what seems to them like random rapid deceleration. You can put a G force clamp (deceleration force, whatever units) and a decel/change of speed clamp, or a delay timer, or whatever. The car clearly has an acceleration clamp, which is why it struggles to merge on to fast moving highways with short and/or twisty ramps.

 

[LowBattery]

No.

There's nothing to "fix" with AP.

AP is working exactly as intended

The problem is the map has the wrong speed limit (or in this case, apparently NO speed limit since he said the sign vanished rather than just became a lower speed)


I think a lot of folks in this thread would benefit by reading page 85 of the current Model 3 Owners manual that explains how AP speed restrictions work.

The page you cited says the speed limit will be reduced to 45 mph in the absence of speed limit information whereas the OP indicated the vehicle slowed to 55. It could be that OP intervened every time before the speed dropped that low, the speed limit information was incorrectly stored as 55, or perhaps the issue is unrelated to missing speed information altogether. In any event, this discussion just highlights what seems to be a common sentiment that AP (in its current state) is not delivering an experience that is 100% confidence-inspiring.

 

[Kabillyhop]

I agree that the cause is maps. What I don't understand is why the maps are so badly out of date. There are many places around here where the map speed limit is years out of date. Why does it take so long to fix?

We also have a BMW SUV which seems to keep its map speed data perfectly up to date. I don't know how it does it, but when there is construction lasting only a few days, I've noticed that it displays the reduced speed limit.

Not complaining, I love the Tesla, but this is one thing I wish they'd raise the priority on.

 

[RobRain]

I agree that the cause is maps. What I don't understand is why the maps are so badly out of date. There are many places around here where the map speed limit is years out of date. Why does it take so long to fix?

We also have a BMW SUV which seems to keep its map speed data perfectly up to date. I don't know how it does it, but when there is construction lasting only a few days, I've noticed that it displays the reduced speed limit.

Not complaining, I love the Tesla, but this is one thing I wish they'd raise the priority on.

Some BMWs read the road signs.

 

[ElectricIAC]

Relying on the car in front of you to pick a max speed (other than TACC insuring you don't hit the guy) makes no sense because if the guy in front of you is a maniac who wants to drive 30 over the limit you probably don't want YOUR car doing that do you?

Given I’m usually the maniac leading the pack, no. I don’t mind it doing that. Lol.

 

[PianoAl]

I’ve had many close calls where I had to take over and slam on the accelerator to keep the car following me from rear ending “my precious.”

This is a side issue, but would the car let that happen?

I've seen video where the car moved forward to avoid a collision, but I've also seen a video of @DirtyTesla getting rear ended.

 

[goldengate]

Phantom braking and the auto wiper issues are the two reasons I chuckle whenever I hear that full self driving (FSD) is just around the corner. If they can't fix these - which are simple - how is this thing going to drive itself with much more complex decision making? Because of this, I rarely use auto pilot and only use TACC with my foot right near the accelerator.

 

[SIr Littlelot]

I have noticed this too and here are my observations as well as possible reasons. I am living in Atlanta so I am using specific examples

Express Lanes I-75:

• These are fairly new in the map system and go in parallel on the west side of the interstate I-75 Marietta area
• Using FSD without navigation set, the car will slow down in areas that are close to off ramps on the regular I-75 which might be very close or even below the Express Lane
• Using FSD with a navigation target set, car still does not recognize the Express Lane to be a part of the interstate and therefore tries to re-route me to take an exit and slows down on that part of the route in order to use an off ramp (that does not exist)
• In both those cases, the selected FSD speed is actively set from e.g. 70 to 55 or even 30 without manual input
• Whenever the speed is being reduced, I interact and set it back to the desired speed hoping the car would upload the input and "learn" that this is not right but I can understand that this is a conflict, especially where an exit or on ramp is directly below the bridge type Express Lane.
  
• It also seems that the two lane part of the Express Lane is not recognized as an interstate and it will not allow me to change lanes by indicating when in FSD
• In the area of Windiy Hill Rd, the car maintains the set speed e.g. 70 but still slows down to about 55

G-400

• Going northbound right after Lenox exit where the toll plaza used to, the car starts to slow down when in FSD without any input even when behind a car that drives the same set speed
• Ironically when going southbound in the same area, it does not happen

Overall I wonder if there is a way to update the map to help overcome those restrictions, like for the smart summon
Tesla Owners Can Edit Maps to Improve Summon Routes - Tesla Motors Club

 

[Silver Ghost]

I agree with @Knightshade, we drive on Hwy 290 in Houston where it had been under major renovation for about 7 years. It's pretty much done, about 3 years behind schedule, the two biggest issue I have with the renovation is 1) striping is not complete and 2) speeds are not updated for Tesla usage. The speed signs appear to be correct but the database that Tesla uses is not. Same portion of the hwy will go from 65mph to 45mph. 45 was the construction speed years ago, it is annoying and dangerous.

Same thing in Temple TX. Once the road construction was done Tesla tried to correct the problem by removing the speed limit, then we got the new update and now at the end of the patch where the speed limit was removed it showed up at 45 mph. Mind you this is a 70 mph zone and most drive 75 to 80. So 75 to 45 is jarring and dangerous.

 

[angelman]

I have the same thing in a specific spot on the 210 freeway towards Pasadena. Everytime it suddenly slows down to 60mph from whatever speed I am going. There is nothing special about the spot on the freeway other than short tunnel maybe 1/2 mile beforehand. I just now have to quickly change the speed whenever I get to that spot. It's annoying and can be dangerous for sure if someone is following close behind

 

[Silver Ghost]

FSD is an exercise in wasting time and money. It will be banned. It's never going to work with other human drivers and all the crazy weather and road conditions.

The worst part is that all these India programmers are clearly on the wrong track on programming AutoPilot and FSD. I am glad I didn't waste $7K and I wish I didn't pay for AutoPilot in my LR AWD.

I do not think it is “Indian programmers” we have now moved to machine learning sir. Programmers are so last decade

 

[SoManyM3s]

Phantom speed limits changes have worsened over the past couple of months. Twice on my drive to Rochester this pas weekend, auto speed on the highway went from 75 to 35 with hard braking. Multiple times were smaller differences. In a few seconds it will revert to normal

 

[momoz74]

Orlando here.. and I-4 is under construction forever (2021 maybe?).. Anyways, there are two spots East and West bound that have been "finalized" for some time and I have this massive slam the brakes to 45mph. Today I was almost rear-ended and I felt so bad for the folks behind me.. clearly pissed at me.

While I know its not approved for construction zone, this stretch is "feature complete" (lol). Big point is it made me wonder. It is always doing this in the right lane and it seems to think I am in the off-ramp lane which I am not. There is one major location (434 exit) EAST bound where I am staying on the interstate but it wants me to exit and get back on i-4. Clearly this is dumb. Traffic is moving along at 65-75 and it ALWAYS (navigation) says to get off i-4 and back on and this event always has a missing speed limit and slams the car down to 45-55.

There really should be some over-ride or option or some NNet feature that realizes your traveling and not exiting and not to slam the brakes.

Very annoying but the two or three spots I am now used to keeping my foot on the accelerator to "push past" these points and it picks back up to normal..

Watching the maps in some of the areas it really thinks I am on a parallel side road and tries to re-route me.


Hope this gets fixed soon!!!

 

[SIr Littlelot]

On another note, Tesla rather suffers from Sudden Deceleration Issues and could be arguable pose similar danger.
Traffic laws would render a rear ending as following to close but the argument could be made that suddenly changing the speed by more than 50-70% could be rendered as a "brake check"....