Collision Avoidance overrode brake press and causing car to veer and hit the curb

[mcfuzz89]

Hi all,

This happened to a buddy of mine - details in bullet points:

• Stopped at a light, on a three lanes + left turning lane road. Car is in the middle lane. Right lane merges into the middle lane after the intersection (thus becoming a 2 lane road).
  
  
• Light turns green, start accelerating and merge into the left lane (not the turning lane) before cross the intersection.
  
  
• As the car crosses the intersection, a van in the middle lane cuts the car off.
  
  
• Slam on brakes - however the car does not stop and instead sharply veers to the left causing the passenger front and rear wheels to hit the curb of the median (where the street light is erected). Impact damages both wheels and causes a flat tire on one; wheels need to be replaced.

Has anyone seen this happen before? We have a video and we can clearly see the van cutting the car off and then the car sharply veering to the left at the moment my buddy claims he smashed the brakes. Car is with Tesla right now to investigate and verify whether there is any damage to suspension and/or brakes... Seems very odd that collision avoidance will override an emergency brake press...

Crappy diagram to illustrate the issue:

 

[C141medic]

I’m no mechanic, but unless it was a total brake system failure, I can’t see how this would occur?

 

[CCIE]

The car has no ability to override the brakes, other than ABS to avoid locking the brakes. It can apply the brakes on its own, but not stop the driver from doing so.

Tesla’s hydraulic braking system is relatively simple compared to other EVs and PHEVs. Their is no mixing of regen and hydraulic when pressing the brake pedal. When you hit the pedal, you’re directly actuating the hydraulic brakes with power assist.

 

[electrictorque]

Hi all,

This happened to a buddy of mine - details in bullet points:

• Stopped at a light, on a three lanes + left turning lane road. Car is in the middle lane. Right lane merges into the middle lane after the intersection (thus becoming a 2 lane road).
  
  
• Light turns green, start accelerating and merge into the left lane (not the turning lane) before cross the intersection.
  
  
• As the car crosses the intersection, a van in the middle lane cuts the car off.
  
  
• Slam on brakes - however the car does not stop and instead sharply veers to the left causing the passenger front and rear wheels to hit the curb of the median (where the street light is erected). Impact damages both wheels and causes a flat tire on one; wheels need to be replaced.

Has anyone seen this happen before? We have a video and we can clearly see the van cutting the car off and then the car sharply veering to the left at the moment my buddy claims he smashed the brakes. Car is with Tesla right now to investigate and verify whether there is any damage to suspension and/or brakes... Seems very odd that collision avoidance will override an emergency brake press...

Crappy diagram to illustrate the issue:

I'm very skeptic about this. Good thing Tesla has very detailed logs.

 

[qdeathstar]

the car will not override the brakes, so something else happened.

 

[mcfuzz89]

The car has no ability to override the brakes, other than ABS to avoid locking the brakes. It can apply the brakes on its own, but not stop the driver from doing so.

Tesla’s hydraulic braking system is relatively simple compared to other EVs and PHEVs. Their is no mixing of regen and hydraulic when pressing the brake pedal. When you hit the pedal, you’re directly actuating the hydraulic brakes with power assist.

There was some discussion amongst some of my peers on whether there is some kind of a "brake-by-wire" technology in the cars - is there something like this in the Model 3? Or is the pedal connected directly to the master brake cylinder through an electric booster?

 

[tvad]

Wouldn't be the first time someone mistakenly pressed the accelerator instead of the brake. That's the first thing that comes to my mind.

 

[mcfuzz89]

Wouldn't be the first time someone mistakenly pressed the accelerator instead of the brake. That's the first thing that comes to my mind.

I don't disagree that this is a possibility in this kind of a scenario, and considering I was not there I can't really say one way or another - but for the sake of the argument, lets go with the notion that there was no pedal confusion.

 

[silenteski]

 

[tvad]

...but for the sake of the argument, lets go with the notion that there was no pedal confusion.

Since i believe “pedal confusion” as you put it (I would not describe it as such) is the most likely cause of the situation, I will step aside from the discussion.

 

[Tam]

...collision avoidance will override an emergency brake press...

Unless you are using a Boeing 737 Max, manual overrides automation every single time.

Boeing 737 Max is different: the automation called MCAS was fighting human manual corrections consistently until it could kill everyone on board.

Since you are not using a Boeing 737 Max, it's a misapplied pedal.

You can buy Tesla Event Data Recorder (EDR) which should confirm the misapplied pedal.

You can also ask for one of the DIY specialists who offer remote data retrieval.

 

[ZappCatt]

Hitting the median is not very surprising, since it is listed in the manual that the auto-pilot/evasion does not see curbs(there have been some funny Smart Summons showing this) so it probably thought that was a "safe area" to navigate to, as opposed to being next to a wall or another car.

My initial thought was how did a Model 3 get beat off the line at an intersection by a van?

 

[electrictorque]

There was some discussion amongst some of my peers on whether there is some kind of a "brake-by-wire" technology in the cars - is there something like this in the Model 3? Or is the pedal connected directly to the master brake cylinder through an electric booster?

The brake pedal is mechanically connect to the master cylinder just like all other cars. No such thing as break by wire.

 

[afadeev]

This happened to a buddy of mine[...]Slam on brakes - however the car does not stop and instead sharply veers to the left causing the passenger front and rear wheels to hit the curb [...] Seems very odd that collision avoidance will override an emergency brake press...

Seems like your buddy is trying to weasel out of driving into a curb in a panic.
Story reeks of BS.

for the sake of the argument, lets go with the notion that there was no pedal confusion.

This is where your buddy's BS becomes your BS.
Brace for impact!

 

[qdeathstar]

Unless you are using a Boeing 737 Max, manual overrides automation every single time.

Boeing 737 Max is different: the automation called MCAS was fighting human manual corrections consistently until it could kill everyone on board.

Since you are not using a Boeing 737 Max, it's a misapplied pedal.

my initial reaction was funny, but then i was thinking sad.

 

[jjrandorin]

Op.. you say you have video of this happening. I am always skeptical of anyone that posts saying "My friend / My co worker / My buddy" had this fantastical thing happen... anyone seen this before?

It always sounds like "Im asking for a friend, yeah thats it, a friend...." who doesnt actually exist. Why do YOU have your "buddys" video, yet didnt post it in this situation to prove what you are saying?

You even know enough about it to draw a diagram, but it wasnt you, it was your buddy, right?

Its also highly (highly highly highly) unlikely the car would override any sort of manual input. the car lets you drive into a garage or other stationary object (see all the "unintended acceleration" threads).

This really sounds like someone trying to find some way out of "I panicked, yanked the wheel and drove into a curb"...err your buddy did, yeah.

 

[Twiglett]

anything that starts with "this happened to a buddy of mine" and includes something like "the car wouldn't stop" is seriously suspect.
Just quit pressing the go pedal instead of the brake and hold the steering wheel - there, fixed it.

 

[Vines]

I had a different issue recently, where AEB triggered, stopping me fully. As I saw the car barreling down from behind I tried to escape with pushing the accelerator gently. I could not use the accelerator to escape the impending rear end collision. Luckily they stopped about 2 feet from my bumper.

Still in this case the brakes are mechanical, so pretty much surprised this could happen.

 

[S4WRXTTCS]

Could this be caused by a debris or a pebble stuck between the brake rotor, and backing plate? Or somewhere in the brake system?

It looks like the braking itself is what caused the car to veer.

One drawback to an EV is that the brakes aren't used very often so you don't really know if something is up with them until you seriously hit the brakes.

I think drivers need to get into the habit of checking their brakes once every drive, and then seriously hit the brakes hard every month or so.

 

[MentalNomad]

There was some discussion amongst some of my peers on whether there is some kind of a "brake-by-wire" technology in the cars - is there something like this in the Model 3?

The Tesla Model 3 is not brake by wire.

Moreover, human steering and braking actions always override the computer systems unless braking causes the wheel(s) to lock, in which case ABS/ traction control kicks in.

Pedal error is dramatically more likely in this instance than any fault in the Model 3.