Unexpected speed up in Autopilot

[Blkflg]

I have had my Model S accelerate unexpectedly on numerous occasions. My wife has also had the same experiences. The below speed behavior happens consistently on a section of road where the speed limit changes from 65mph to 55mph then to 45mph:

@65, autopilot allowed 70,
@55, it allowed 60,
@45, it allowed 50 for a few hundred yards then tried to accelerate to 57 even though the 45mph speed limit was displayed on the dash - Autopilot canceled by me.

The indicator on the dash shows the cruise control speed is 57 although neither my wife or I set that speed.

On one occasion when going the opposite direction on the same section of road this occurred:
Going into the 45mph zone, AP was engaged, 50mph was attained.
In the 55mph zone, 60mph was attained.
In the 65mph zone, the BRAKES came on. The accelerator was used to override the deceleration and AP was eventually turned off.

Other information:
The speed limit warning setting button was set to 'absolute' 75mph
The speed limit warning setting 'relative' button was de selected although the setting was +12mph.
Could this have any effect on overriding the Autopilot?

Any thoughts on this behavior?

So far Tech support has not responded with an explanation.

 

[rjcbox]

Odd....and I've never had this happen in 20k miles, most of which were autopilot. Having said that, I have had unintended acceleration when the speed limit sign read incorrectly (very rare), but you indicated the car read the sign correctly.

They should be able to pull logs and investigate

 

[Burnt Toast]

Did you change lanes?

 

[silentsnow31802]

I'm pretty sure the speed limit sign on the display is just a display. I can set my AP for 80 in a zone where 30 is displayed if I want. It all depends on what the cruise control is set to max at.

 

[S4WRXTTCS]

That's the expected behavior with exception to accelerating to 57mph in a 45mph.

On undivided roads AP only allows for up to 5mph over the speed limit so it tries to maintain that for those types of roads. Whether the speed limit goes up or down.

So in theory this seems like a neat thing aside from the 5mph over being a little slow for some of us.

But, in practice it doesn't really work all that well. The reason is sometimes it will misread the sign or it won't see the sign and will continue on with it thinks is the speed limit. Or it suddenly thinks its an divided highway where it doesn't have the 5 over restriction so it zooms to 10 over the speed limit (or whatever your set point over is). In some cases it simply loses it's mind and picks some random number like 52.

I imagine the problem is worse in Oregon because for some reason you guys seem obsessed with speed limit changes every thousand feet in 5mph increments. Like couldn't they just pick one speed limit and be happy with it? Plus I've noticed the AP system misreading the signs more in Oregon than in WA.

Now nothing I just said should be received with any confidence at all. The reason - I barely remember its behavior since I stopped using it on those types of roads because it was annoying.

 

[Tomnook]

Here in the U.K. I'm fairly certain that both AP1 and AP2 relate speed limits to geo co-ordinates - possibly from Google maps. Personally, I found speed limit detection far better with AP1. Now, with AP2 my X will often travel a couple of hundred yards into a lower speed zone without 'detecting' it.

Other examples are a couple of roads I regularly use where the speed was reduced two or three years ago - neither AP1 or AP2 pick this up and neither does regular Google maps on a phone.

 

[BerTX]

Here in the U.K. I'm fairly certain that both AP1 and AP2 relate speed limits to geo co-ordinates - possibly from Google maps. Personally, I found speed limit detection far better with AP1. Now, with AP2 my X will often travel a couple of hundred yards into a lower speed zone without 'detecting' it.

Other examples are a couple of roads I regularly use where the speed was reduced two or three years ago - neither AP1 or AP2 pick this up and neither does regular Google maps on a phone.

There is definitely a gps database that the car accesses. Another way to know this is that when turning onto a different road with a different speed limit, the car will sometimes display the new speed limit, even though there has not been a speed limit sign yet. Now, which source has priority and when it uses the database and when it uses the sign recognition, I don't have much of a grasp on as yet.

 

[ZAKEEUS]

There is definitely a gps database that the car accesses. Another way to know this is that when turning onto a different road with a different speed limit, the car will sometimes display the new speed limit, even though there has not been a speed limit sign yet. Now, which source has priority and when it uses the database and when it uses the sign recognition, I don't have much of a grasp on as yet.

Is there any proof that sign recognition has ever been used. It seems like it's completely GPS based to me.

 

[Blkflg]

A slightly different occurance happened today:
In a 65mph zone AP was activated - the car tried to accelerate to 77mph. This happened on a section of divided road as well as a section of undivided road.
77 was indicated on the dashboard cruise control circle (TCC?).
Cruise control WAS NOT SET by driver. Where does the 77 come from?

 

[BerTX]

Is there any proof that sign recognition has ever been used. It seems like it's completely GPS based to me.

I see it change in construction areas, where I'm pretty sure the database does not contain all the transient speed limit changes. It changes right where the temporary speed limit sign is located.

 

[BerTX]

A slightly different occurance happened today:
In a 65mph zone AP was activated - the car tried to accelerate to 77mph. This happened on a section of divided road as well as a section of undivided road.
77 was indicated on the dashboard cruise control circle (TCC?).
Cruise control WAS NOT SET by driver. Where does the 77 come from?

You mean you just then set the AP on, and it accelerated? I have seen this when pulling the speed wand back to set TACC on and accidentally pulled it up and back, instead of back, thus bumping the speed setting up 5 mph. Don't know if AP would do that.

 

[Blkflg]

You mean you just then set the AP on, and it accelerated? I have seen this when pulling the speed wand back to set TACC on and accidentally pulled it up and back, instead of back, thus bumping the speed setting up 5 mph. Don't know if AP would do that.

Yes. When AP was turned on, it accelerated to 77.
It seems that TACC is somehow automatically being set to 77 or in previous incidences +12 mph over the speed limit. Every other car I've driven, cruise control is deactivated either manually or when the car is turned off.
Again - the big question is where is the 77 (or mph +12) coming from?

 

[Drone Flyer]

I'm pretty sure the speed limit sign on the display is just a display. I can set my AP for 80 in a zone where 30 is displayed if I want. It all depends on what the cruise control is set to max at.

You can set the cruise control to whatever you want but AP will only go to 10 km/r over the speed limit.
If the speed limit is 30 and you set AP while doing 80, it will immediately slow down to 40, or whatever speed limit you programmed above the limit maxiing out at 10 over.

 

[Tomnook]

I see it change in construction areas, where I'm pretty sure the database does not contain all the transient speed limit changes. It changes right where the temporary speed limit sign is located.

That's true! Only ever happened to me with AP1 - could be 'over the air' updates similar to the live traffic information we receive on the in-car Google navigation. But then why doesn't it happen with AP2? Anyone ever had construction speed restrictions with AP2?

 

[silentsnow31802]

You can set the cruise control to whatever you want but AP will only go to 10 km/r over the speed limit.
If the speed limit is 30 and you set AP while doing 80, it will immediately slow down to 40, or whatever speed limit you programmed above the limit maxiing out at 10 over.

Mine does not do this. Today I had AP set to 85Mph in a 65 zone. Was a multiple lane highway though. I hear the limits are only on 1 lane highways?