Autopilot seems to love using ABS...

[thatisug]

Hey Folks,

New Model S owner, and am curious if it is normal for Autopilot to use ABS so much?

My drive from home to work (~30 miles each way), I drive about 20 of those miles on the interstate in SoCal using Autopilot. On the drive ABS seems to kick in about 3-4 times during my commute to work when Autopilot brakes the car. The car is not braking hard but it may brake a tad bit harder than normal (aka a car merges into my lane and autopilot brakes a little harder than normal) and the ABS on the front tires will kick in (you can hear and feel it).

While the car was in for service recently I asked them to check it and they came back with "thats normal" after the service visit. Seems extremely odd to me. When I drive without Autopilot I have never heard nor felt ABS kick in, even when I try to brake hard-ish and cause it... Is this truly normal for Autopilot or should I take it back into the Service center?

I have the MS75 with AP 2.0 - just received the car 9/16.

 

[thatisug]

Also - I assume have AP2.0 - I purchased the car with "Enhanced Autopilot" - so I think that is AP2.0? Not sure if there is a way to tell...

 

[LosAltosChuck]

If it was ABS you would *feel* it as hard braking and the ABS vibration.. I think what you are feeling is the haptic feedback when the car thinks you are drifting over a lane line. The car introduces a more or less subtle (depends on the car I think, my friend’s is far more noticeable than mine) vibration into the steering wheel. It actually has no affect on steering or braking, though sometimes it feels weird. It also (on my car at least) does it when I’m not crossing a lane, but if you look at the console display you’ll see that it’s likely confused about lane lines at that moment.

 

[kort677]

I have AP1 and have never had the car use the ABS ap engaged or not.

 

[thatisug]

If it was ABS you would *feel* it as hard braking and the ABS vibration.. I think what you are feeling is the haptic feedback when the car thinks you are drifting over a lane line. The car introduces a more or less subtle (depends on the car I think, my friend’s is far more noticeable than mine) vibration into the steering wheel. It actually has no affect on steering or braking, though sometimes it feels weird. It also (on my car at least) does it when I’m not crossing a lane, but if you look at the console display you’ll see that it’s likely confused about lane lines at that moment.

Thanks for the reply - I am fairly certain it is the ABS kicking in.. you can hear the loud "clicking" in the brakes (front tires) and feel the pulsing in the car as it slows down. About 5 miles of my initial drive is on a winding road, and the lane crossover vibration tends to give he steering wheel a nice little vibration if I edge to close to the lines.. and the Brake/ABS kicking in that I am referring is certainly different to that of the steering wheel vibration for the lane crossover warning.

 

[kort677]

Thanks for the reply - I am fairly certain it is the ABS kicking in.. you can hear the loud "clicking" in the brakes (front tires) and feel the pulsing in the car as it slows down. About 5 miles of my initial drive is on a winding road, and the lane crossover vibration tends to give he steering wheel a nice little vibration if I edge to close to the lines.. and the Brake/ABS kicking in that I am referring is certainly different to that of the steering wheel vibration for the lane crossover warning.

you're using the AP on winding roads? I tried that once, it doesn't work too well.

 

[BrettS]

I don’t believe that the AP system specifically engages the ABS system, but rather AP calls for the brakes and ABS kicks in as normal, if needed. I would try to manually duplicate the conditions where you feel that ABS is kicking in. Leave AP disengaged and try to stop with about the same amount of braking force manually and see if you experience the same sensation.

 

[brkaus]

Mine does the same. I’m not sure it’s ABS, I’m thinking it’s just the power booster applying the brakes in steps.

 

[croman]

Mine does the same. I’m not sure it’s ABS, I’m thinking it’s just the power booster applying the brakes in steps.

Yes, its not ABS, in my opinion, but I can understand how OP thinks its ABS because it has a vibration but its not the pulsing of ABS.

 

[Jmuessig]

I've never felt anything like this before. Did you server center drive the car with you and feel what your feeling? If not that would be my very first step!

 

[Beswick]

I have the same thing happen to me on the 405 when using autopilot. Sounds and feels like ABS. Scared me the first time it happened because I didn't think the car needed to brake that hard. Autopilot seems to just like braking late and hard.

 

[LosAltosChuck]

Thanks for the reply - I am fairly certain it is the ABS kicking in.. you can hear the loud "clicking" in the brakes (front tires) and feel the pulsing in the car as it slows down. About 5 miles of my initial drive is on a winding road, and the lane crossover vibration tends to give he steering wheel a nice little vibration if I edge to close to the lines.. and the Brake/ABS kicking in that I am referring is certainly different to that of the steering wheel vibration for the lane crossover warning.

I see. I agree what you are describing isn’t the haptic feedback of the lane departure warning. On the other hand, it doesn’t sound like ABS behavior either. It sounds like computer controlled braking, outside the ABS domain. I’ve also heard clicks in the brake mechanism, and I have noticed a tendency for Tesla’s systems to respond late and aggressively (and roughly), but never have I experienced the system entering ABS.

To understand what it means to be “in ABS”, one has to realize that it is the absolute maximum braking the vehicle will achieve via the automated systems. Interestingly, skilled human drivers can brake better than ABS (by holding a braking pressure just short of the point where ABS kicks in), but when the ABS kicks in, there will be no further increase in braking unless the mu of the road surface increases.

So, you may be experiencing harder than expected braking, and even some (poorly implemented) algorithmic pulsing, but unless you are also pretty much slammed into the shoulder harness, I doubt you are in ABS (unless you’re driving on snow). When your issue happens, if you can increase braking force by manually mashing the brake pedal, you are not in ABS (but doing that might put you there if you mash hard enough). I don’t recommend trying that on a public road...

 

[Mbrockus]

Have you tried changing the car length follow distance setting to 7? I noticed in stop n go traffic having that on a lower value resulted in the harder braking. Setting at 5-7 has stopped me from looking like I’m at a Slayer concert.

 

[J1mbo]

If you try to move closer to the car in front after coming to a full stop, the brakes will sound like ABS is kicking in as you ease off the throttle.

 

[thatisug]

I see. I agree what you are describing isn’t the haptic feedback of the lane departure warning. On the other hand, it doesn’t sound like ABS behavior either. It sounds like computer controlled braking, outside the ABS domain. I’ve also heard clicks in the brake mechanism, and I have noticed a tendency for Tesla’s systems to respond late and aggressively (and roughly), but never have I experienced the system entering ABS.

To understand what it means to be “in ABS”, one has to realize that it is the absolute maximum braking the vehicle will achieve via the automated systems. Interestingly, skilled human drivers can brake better than ABS (by holding a braking pressure just short of the point where ABS kicks in), but when the ABS kicks in, there will be no further increase in braking unless the mu of the road surface increases.

So, you may be experiencing harder than expected braking, and even some (poorly implemented) algorithmic pulsing, but unless you are also pretty much slammed into the shoulder harness, I doubt you are in ABS (unless you’re driving on snow). When your issue happens, if you can increase braking force by manually mashing the brake pedal, you are not in ABS (but doing that might put you there if you mash hard enough). I don’t recommend trying that on a public road...

Thanks LosAltosChuck for the reply! Sorry I did not chime in sooner. Looks like there is now a similar thread ongoing, and the general consensus is exactly what you said. That this is not ABS, but rather a pulsing by TACC on the break pedal. I will be following the newer thread and seeing where it goes.

Link:
Hard breaking with TACC in stop-n-go traffic

 

[CHG-ON]

Never had this with my AP1.

 

[chillaban]

Yeah I've only had this happen with AP2, never AP1. It is more of a pulsing THUD from the system suddenly deciding it's time to brake. The actual sound seems to be the brake pedal falling as the cylinder moves beneath it.

 

[Upgrade00]

You have your AP car distance to close. I have to swtich back from 3-4. 3 it uses the breaks more and 4 it use it less.

 

[comanchepilot]

the ABS is not 'selected' by the AP. The ABS works when the car wants to slow down and the braking level commanded causes the wheels to lock up.

As others have noted - its because your speed is too high for your distance selected in the AP. Either slow down or increase your distance selected.