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Scary highway brake

Bill55 said:
Not doubting anyone, but especially with one pedal driving 99.99 percent of the time in car data shows the human pressed the wrong pedal.
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That is probably the case when there is an accident where unintended acceleration causes the car to hit an object but these incidents have the car braking after the feeling of acceleration (either regen braking stops which makes it feel like the car accelerated - which I think is the case or the car accelerated). If they hit the wrong pedal, they would have quickly accelerated into the object as they pressed harder to try to stop. Since the car does brake after the momentary feeling of acceleration, it seems like rather than the regen being additive to the braking effort, the regen is missing.

Do all the incidents involve the car telling the driver to brake? That would at least narrow the debug path.
 
I think the car didn’t actually accelerate. It just lost the regen torque, and brake pad is barely touching. It feels like acceleration. But it just lost braking power. So push brake harder will stop it. You know as a human, the first reaction is “am I pushed the wrong paddle?” :( so 1 more seconds hesitation made this situation worse.

Little bit deeper if anyone is interested. My guess is when the brake paddle touch the rotor, the sudden change of phase made motor control lost the detection of motor rotor position. If you have a high brake torque at this time. It my lost completely. Or maybe push the power to wrong direction. I think it is a common issue with EV. All the control engineer are facing it and solving it one way or another. It is tricky and may have coner cases. I cannot reproduce it later today. Hopefully the data Lucid got from my car help then fix something.

I am not lucid engineer so could be completely wrong. No responsible for it.
 
It happened with me as well a few times as well. As soon as the car has a collision warning it lets go of the Regen braking and depends solely on the car brakes which probably is causing this thus throwing us off regarding how much to depress the brake pedal
 
Bill55 said:
Not doubting anyone, but especially with one pedal driving 99.99 percent of the time in car data shows the human pressed the wrong pedal.
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this is how victim blaming starts :D . you won't believe it until you experience it yourself. heck, i might have wrote it off as a user error like you said but since i have gone through it, i can attest what OP is saying here.
 
creair said:
It happened with me as well a few times as well. As soon as the car has a collision warning it lets go of the Regen braking and depends solely on the car brakes which probably is causing this thus throwing us off regarding how much to depress the brake pedal
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a reasonable explanation but why did the car go off the regen when the collision warning appeared? shouldn't it stay on because my car is set to high regen and my foot was off the accelerator? as i described in my original thread, i'm pretty sure i got the collision warning after i started applying the brakes so your theory somewhat makes sense (i.e, i took my foot off accelerator, high regen started, i braked lightly, collision warning came on, high regen turned off which caused the car to lunge and i braked harder).
 
hellolucid said:
a reasonable explanation but why did the car go off the regen when the collision warning appeared? shouldn't it stay on because my car is set to high regen and my foot was off the accelerator? as i described in my original thread, i'm pretty sure i got the collision warning after i started applying the brakes so your theory somewhat makes sense (i.e, i took my foot off accelerator, high regen started, i braked lightly, collision warning came on, high regen turned off which caused the car to lunge and i braked harder).
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Honestly it threw me off a few times as well. It happened with me in stop and go traffic. Only reasonable liability thing I can think of is Auto Braking as it might not know if motor Regen is working or not ( in worse case scenario where motor fails) so it only wants to depend on brakes for emergency collision system or maybe regulatory. It definitely throws you off where if not paying attention will definitely cause an accident.
I don't remember that happening in my model x ( sold in 2019) so don't even remember anything about the car other than being louddd inside
 
creair said:
Honestly it threw me off a few times as well. It happened with me in stop and go traffic. Only reasonable liability thing I can think of is Auto Braking as it might not know if motor Regen is working or not ( in worse case scenario where motor fails) so it only wants to depend on brakes for emergency collision system or maybe regulatory. It definitely throws you off where if not paying attention will definitely cause an accident.
I don't remember that happening in my model x ( sold in 2019) so don't even remember anything about the car other than being louddd inside
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i think you have a good explanation (i.e, regen and auto braking working as separate systems) but Lucid should document this behavior and put it on the manual.
 
I do think there are times when the regen releases, during crash avoidance scenarios. It has surprised me because you need to press the break harder at exactly the same moment you need to stop shorter. Keep us updated on Lucid feedback.
 
MoniputerLM said:
Nope.
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If the car is behaving as expected, any press of the brake disables the accelerator. I tried a few different scenarios on the way to work. Every time as soon as I touched the brake the accelerator was cut.

I have noticed some odd behavior occasionally when transitioning from cruise on to off. I’ll have to pay closer attention on road trip this week.

A lack of regeneration braking when it is expected could feel like acceleration and the braking point is much earlier without regeneration, so you would be past your brake point by the time you realize there is no regeneration and a hard brake would be required.

Is this possible or do you think the car was truly accelerating unexpectedly?
 
I came here looking to see if this happened to anyone else as this just happened to me too for the second time!!! Incredibly scary. Really hope Lucid can find this and fix it.
 
The situation is probably magnified by the sheer weight of the vehicle. If regen can bring it to a swift halt and regen cuts off, then the car will definitely feel like it is accelerating because it's no longer decelerating. We went to Six Flags and the brakes that hit at the end of the coaster swiftly bring you to a stop, but then they cut off and we're "accelerating" again because we're no longer actively being slowed down. Makes perfect sense. The question is - does regen accidentally cut off at times. Otherwise sounds like everything is operating as normal.
 
Bbq9 said:
I experienced this today
Pretty certain I was not pressing the Brake pedal when the warning came on
the loss of regen was like the car was suddenly “running away”
disconcerting to say the least
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Just curious.... are you on the latest and greatest software update? 2.0.24?
 
Bbq9 said:
I experienced this today
Pretty certain I was not pressing the Brake pedal when the warning came on
the loss of regen was like the car was suddenly “running away”
disconcerting to say the least
Click to expand...
+1 just happened today for the first time.

I was coming off of the highway, in full regen. There was a car stopped at the light ahead, I knew I'd need brake input eventually but I let the car regen as much as I could.

Then it happened just as I was about to gently add brake pressure. I got the forward collision warning, and then I started my brake input and the car started to lurch forward (definitely just regen cutting out), now obviously I had not planned for not having regen suddenly so I really had to slam the brakes to get stopped short of the car in front. Went into ABS for the first time.

Thankfully, the brakes on the Air are stellar.

Idk if it's safety issue per se but it's a drivability issue for sure. Gets your blood pumping though.
 
windscar911 said:
+1 just happened today for the first time.

I was coming off of the highway, in full regen. There was a car stopped at the light ahead, I knew I'd need brake input eventually but I let the car regen as much as I could.

Then it happened just as I was about to gently add brake pressure. I got the forward collision warning, and then I started my brake input and the car started to lurch forward (definitely just regen cutting out), now obviously I had not planned for not having regen suddenly so I really had to slam the brakes to get stopped short of the car in front. Went into ABS for the first time.

Thankfully, the brakes on the Air are stellar.

Idk if it's safety issue per se but it's a drivability issue for sure. Gets your blood pumping though.
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Dang that’s scary.
 
I just experienced it. In a faster freeway lane, rounding a corner and visually being blocked by a semi in the other lane. Couldn’t see that traffic had slowed in front of me because of the blocking semi. I began to brake. The collision warning came on and it felt as if the brakes got ‘soft’ making me brake harder. Not sure if the ABS came on. This all happened in a split second. Definitely didn’t hit the wrong pedal because I was already breaking. I avoided collision but am very concerned about this issue. To me, it seems like a problem with the collision warning and braking system.
 
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