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ibooster braking system logic issue [and discussion around brake failure claim in shanghai]

sunjack

Member
Apr 20, 2021
28
2
Shanghai, China
Skepticism about what?
I do not know how the public respond to recent accidents in USA, but obviously the situation is not good in China. After series of accidents related to braking system and sudden unintended acceleration, lots of potential M3 buyers like me are now wondering whether M3 is really safe or not.
Since we are not pros and consider most comments in China now to be very emotional, we also want to hear voice worldwide. Is that intention strange?
I'm looking forward to more technical analysis instead of something else.
IMO, blended or not, it doesn’t matter, as long as the brake can stop the car properly. So far, I haven’t heard anyone complaining about that here.
 

skywalker2go

Member
Apr 26, 2021
13
-8
China
IMO, blended or not, it doesn’t matter, as long as the brake can stop the car properly. So far, I haven’t heard anyone complaining about that here.
I'm afraid not. Whether a stiff braking pedal is expected in such cases still needs more digging.
According to what you guys have discussed above, ABS seemed to be triggered in stopcrazypp‘s video. My question is, why wasn't ABS triggered in the 1st attempt? The only difference seemed to be "pump the brakes" in the 2nd attempt. Will that trigger ABS? Note that ground conditions were almost the same in both attempts.
Besides, more and more cases show that road conditions were relative good in such accidents, e.g. Ms. Zhang‘s case, there is no evidence which shows that the road is either slippy or sandy. Then how got ABS triggered?
ABS-like behavior should not be expected and braking pedal should be pressed down smoothly, thus avoiding an accident. I think that’s what most people really care about, not just telling people what happens when someone rolls on a slippy ground.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
8,836
9,800
Riverside Co. CA
Skepticism about what?
I do not know how the public respond to recent accidents in USA, but obviously the situation is not good in China. After series of accidents related to braking system and sudden unintended acceleration, lots of potential M3 buyers like me are now wondering whether M3 is really safe or not.
Since we are not pros and consider most comments in China now to be very emotional, we also want to hear voice worldwide. Is that intention strange?
I'm looking forward to more technical analysis instead of something else.

There is no "series of accidents related to braking system malfunction" nor is there any proof anywhere that a single case of "sudden unintended acceleration" is actually that, and not the person pushing the wrong pedal.

With that being said, if the model 3 makes you uncomfortable, in china, you have many more choices than we do here for what appear to be viable electric vehicles. since you are uncomfortable, why not pivot to purchasing one of those instead?
 

skywalker2go

Member
Apr 26, 2021
13
-8
China
There is no "series of accidents related to braking system malfunction" nor is there any proof anywhere that a single case of "sudden unintended acceleration" is actually that, and not the person pushing the wrong pedal.

With that being said, if the model 3 makes you uncomfortable, in china, you have many more choices than we do here for what appear to be viable electric vehicles. since you are uncomfortable, why not pivot to purchasing one of those instead?
In fact I have already considered other brands. But whether to buy or not, has not been decided yet. Maybe the whole EV industry still needs more time to get mature. Since your next doubt could be why not pivot to oil cars. OK, that's not what we can completely determine. Plz search online related policy in China , especially in mega cities like Beijing and Shanghai.

To tell the truth, I have paid attention to M3 for more than half year and also tried driving several times. I was in general satisfied with its performance and planned to buy one within next few months, meanwhile, I cannot simply ignore this event. Well, it's just like a child waiting for Christmas present but gets suddenly grabbed by others.

I personally consider both "TESLA is always good" and “TESLA must have design issues” to be emotional. What I want is strong and solid evidence, not what happens now: Tesla shouts , I'm innocent, believe it or not, and Ms Zhang shouts back, no no, whatever you say, i just don't believe it. Stop playing kids' game and show me some proof.
People like me may lack professional background in auto domain, but we have at least basic logic and will judge based on available info online, after all there are also so many pros out there in the public. That's why i want to hear technical analysis from Tesla circle ( the other side already enough ) and keep doubting,however some guys always reply that this must be the driver's fault. How could he be so sure about that?
I believe paradox will eventually appear from at least one side and hope i can find it myself.
 

Electric Dream

Pilots the Millennium Milkfloat
Jul 21, 2016
1,682
2,759
UK
Tesla has produced the proof. It's you and others who are not prepared to accept that it shows the driver was to blame or perhaps can't understand it. Either way, that's not Tesla's fault.

More data would be nice to have, but from what's already been released it's obvious where the blame lies.
 

Gasaraki

Active Member
Oct 21, 2019
1,668
1,070
Syracuse, NY
In fact I have already considered other brands. But whether to buy or not, has not been decided yet. Maybe the whole EV industry still needs more time to get mature. Since your next doubt could be why not pivot to oil cars. OK, that's not what we can completely determine. Plz search online related policy in China , especially in mega cities like Beijing and Shanghai.

To tell the truth, I have paid attention to M3 for more than half year and also tried driving several times. I was in general satisfied with its performance and planned to buy one within next few months, meanwhile, I cannot simply ignore this event. Well, it's just like a child waiting for Christmas present but gets suddenly grabbed by others.

I personally consider both "TESLA is always good" and “TESLA must have design issues” to be emotional. What I want is strong and solid evidence, not what happens now: Tesla shouts , I'm innocent, believe it or not, and Ms Zhang shouts back, no no, whatever you say, i just don't believe it. Stop playing kids' game and show me some proof.
People like me may lack professional background in auto domain, but we have at least basic logic and will judge based on available info online, after all there are also so many pros out there in the public. That's why i want to hear technical analysis from Tesla circle ( the other side already enough ) and keep doubting,however some guys always reply that this must be the driver's fault. How could he be so sure about that?
I believe paradox will eventually appear from at least one side and hope i can find it myself.
In the US, we operate on the assumption that we are innocent until proven guilty.
Unless someone can prove and have "strong and solid evidence" that Tesla's brakes are faulty, I'm not going to believe what a crazy lady is shouting.

Tesla and the Chinese government have stated nothing was wrong with the car.
 
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Big Earl

bnkwupt
Jul 12, 2017
5,296
9,758
Springfield, VA
Random thoughts
  • The protestor at the Chinese auto show wasn't directly involved in the accident in question; her father was the driver
  • Model 3 and Model Y (not sure about S/X) use the Bosch iBooster 2, not the first generation Bosch iBooster
  • Regen and friction brakes are NOT blended in any Tesla regardless of powertrain configuration
    • Yes, the iBooster and iBooster 2 both support blended braking, but Tesla does not use that feature
  • Sudden unintended acceleration in Tesla vehicles has always turned out to be driver error and pedal misapplication
Good discussion on what's going on with FUD in China on Rob Maurer's Tesla Daily podcast:


And a data point for the OP: 100,000+ miles on our Model 3 with no braking issues whatsoever.
 

skywalker2go

Member
Apr 26, 2021
13
-8
China
Random thoughts
  • The protestor at the Chinese auto show wasn't directly involved in the accident in question; her father was the driver
  • Model 3 and Model Y (not sure about S/X) use the Bosch iBooster 2, not the first generation Bosch iBooster
  • Regen and friction brakes are NOT blended in any Tesla regardless of powertrain configuration
    • Yes, the iBooster and iBooster 2 both support blended braking, but Tesla does not use that feature
  • Sudden unintended acceleration in Tesla vehicles has always turned out to be driver error and pedal misapplication
Good discussion on what's going on with FUD in China on Rob Maurer's Tesla Daily podcast:


And a data point for the OP: 100,000+ miles on our Model 3 with no braking issues whatsoever.
Just one comment on the video, ask any of your Chinese friend and you will find how many basic facts “happened to" be ignored by dear Rob, which have already been reported over and over by stream media in China. That's why the public got so excited and angry.
 

Gauss Guzzler

Member
Dec 27, 2020
207
258
Thousand Oaks, California
People like me may lack professional background in auto domain, but we have at least basic logic and will judge based on available info online, after all there are also so many pros out there in the public. That's why i want to hear technical analysis from Tesla circle ( the other side already enough ) and keep doubting,however some guys always reply that this must be the driver's fault. How could he be so sure about that?
Double check your basic logic. Telsa has a million cars on the road and 1 (crazy) woman says she thinks that maybe her dad thinks that maybe he hit the brakes as he sped thru town.

Do the math and you'll see that Tesla brakes are *exactly* 100% reliable. That's why everyone is sure it's the driver's fault.

Could Zhang's car have a 1-in-a-million brake failure? Maybe but it's extremely unlikely. Could it have a brake failure that somehow fixed itself without leaving any evidence? No. That has never happened on any car from any maker anywhere ever.
 
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Gauss Guzzler

Member
Dec 27, 2020
207
258
Thousand Oaks, California
Just one comment on the video, ask any of your Chinese friend and you will find how many basic facts “happened to" be ignored by dear Rob, which have already been reported over and over by stream media in China. That's why the public got so excited and angry.
I'm only aware of 2 facts in this case. The guy was speeding and the woman is crazy. If there are more *facts* please share them with us.
 

Big Earl

bnkwupt
Jul 12, 2017
5,296
9,758
Springfield, VA
Just one comment on the video, ask any of your Chinese friend and you will find how many basic facts “happened to" be ignored by dear Rob, which have already been reported over and over by stream media in China. That's why the public got so excited and angry.

I'm curious what those additional basic facts are. I'm genuinely unfamiliar, so please help me understand.
 

TunaBug

Member
Mar 27, 2021
35
26
Kirkland, WA
While the paper referenced has a lot of the useful information to reference, I would caution about fully believing the overall theory that it pushes. The NHTSA ODI seems to disagree with it:
"As part of its evaluation of DP20-001, ODI reviewed two defect theories alleging vehicle-based causes of SUA in the subject vehicles. Both theories were developed by Dr. Ronald Belt, the first in 2018 and the second in 2020. A paper describing the most recent theory was submitted to NHTSA by the petitioner and is based upon Dr. Belt’s review of EDR data from the crash reported in VOQ 11206155. The other theory was referenced by the consumer who submitted VOQ 11206155 and is based upon Dr. Belt’s third-hand reconstruction of log data from an unknown SUA event. Both papers are based upon incorrect event data, incorrect reconstructions of event dynamics, and false assumptions regarding vehicle design factors."
https://static.nhtsa.gov/odi/inv/2020/INCLA-DP20001-6158.PDF

Note that in general, Tesla does not blend regen brakes into the brake pedal in the traditional sense (as hybrids do). The way hybrids do it is by when you press the brakes, the system gives x-amount of regen along with it (to net to the expected braking force). Lifting off the accelerator pedal does not provide regen braking, only pressing the brake pedal.

The regen in Teslas instead is 100% controlled by the lifting off the accelerator pedal. However the braking system still has to do some blending even in this case (to not interfere with each other).

How do you search for these ODIs? Is there a place on nhtsa.gov where I can search specifically for investigations into Teslas? (Or Toyotas, or...).

I read most of the ODI document that you linked to. More than 50%, but I confess I skimmed a bit.

My very high level summary of that: the reports that they investigated did not show any brake malfunction, if anything they showed drivers accidentally mashing the accelerator when they perhaps meant to mash the brake pedal; and Belt's papers are best ignored.

That does not sound to me like a malfunction of the car.

But I have to wonder: could some people have muscle memory for bringing a car to a stop that consists of "use brake to stop the car, then press harder for full stop", and that causes them to occasionally mess up on cars with aggressive regen: the car mostly comes to a stop via regen, but if the foot is still over the accelerator (while regen is slowing the car), and then without thinking the next step is "mash the pedal to come to full stop" and they do that without moving the foot to the brake pedal? I haven't done this, but I have noticed that now when I'm coming to a red light or stop sign that frequently my foot is hovering over the accelerator, not the brake.

Also, not all hybrids do regen only via brake pedal. On my wife's 2020 Honda Insight there is regen when you take your foot off the accelerator, and paddles behind the steering wheel to let you adjust that regen up/down. And regen will be used when going downhill to attempt to keep at the set adaptive cruise speed, but it won't fade in the brakes to maintain speed.
 
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stopcrazypp

Well-Known Member
Dec 8, 2007
10,202
5,108
How do you search for these ODIs? Is there a place on nhtsa.gov where I can search specifically for investigations into Teslas? (Or Toyotas, or...).

I read most of the ODI document that you linked to. More than 50%, but I confess I skimmed a bit.

My very high level summary of that: the reports that they investigated did not show any brake malfunction, if anything they showed drivers accidentally mashing the accelerator when they perhaps meant to mash the brake pedal; and Belt's papers are best ignored.

That does not sound to me like a malfunction of the car.
I searched specifically for that using google and keywords. I'm not sure how to do the same however with the NHTSA or ODI system however.

But I have to wonder: could some people have muscle memory for bringing a car to a stop that consists of "use brake to stop the car, then press harder for full stop", and that causes them to occasionally mess up on cars with aggressive regen: the car mostly comes to a stop via regen, but if the foot is still over the accelerator (while regen is slowing the car), and then without thinking the next step is "mash the pedal to come to full stop" and they do that without moving the foot to the brake pedal? I haven't done this, but I have noticed that now when I'm coming to a red light or stop sign that frequently my foot is hovering over the accelerator, not the brake.
Yeah, there are some people that threw out the theory that "one pedal driving" is the culprit of pedal misapplications in Teslas, but there is no evidence of this. I believe even the ODI mentioned there doesn't appear to be evidence suggesting that Tesla has disproportionally more pedal misapplications than other manufacturers (which in itself may suggest a design defect, even if the systems were all working properly). I don't really believe that either, given people have long pressed the wrong pedal well before regen braking even existed in cars.
Also, not all hybrids do regen only via brake pedal. On my wife's 2020 Honda Insight there is regen when you take your foot off the accelerator, and paddles behind the steering wheel to let you adjust that regen up/down. And regen will be used when going downhill to attempt to keep at the set adaptive cruise speed, but it won't fade in the brakes to maintain speed.
Yeah, my point there is not to be absolute (as in all hybrids operate the same), just that the blending originated from them (iBooster was originally developed for hybrids).
 
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Big Earl

bnkwupt
Jul 12, 2017
5,296
9,758
Springfield, VA
Post 10 of this thread contains a link that I found quite informative. That's just a single investigation, but that investigation considered data from many different people reporting a problem.

Quoting from the summary portion of that link:

"After reviewing the available data, ODI has not identified evidence that would support opening a defect investigation into SUA in the subject vehicles. In every instance in which event data was available for review by ODI, the evidence shows that SUA crashes in the complaints cited by the petitioner have been caused by pedal misapplication. There is no evidence of any fault in the accelerator pedal assemblies, motor control systems, or brake systems that has contributed to any of the cited incidents. There is no evidence of a design factor contributing to increased likelihood of pedal misapplication. The theory provided of a potential electronic cause of SUA in the subject vehicles is based upon inaccurate assumptions about system design and log data."

Nothing about this investigation of more than 200 incidents suggests that there are additional basic facts that have been unreported. Still waiting on @skywalker2go to clarify what those missing pieces of information are.
 
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stopcrazypp

Well-Known Member
Dec 8, 2007
10,202
5,108
I personally consider both "TESLA is always good" and “TESLA must have design issues” to be emotional. What I want is strong and solid evidence, not what happens now: Tesla shouts , I'm innocent, believe it or not, and Ms Zhang shouts back, no no, whatever you say, i just don't believe it. Stop playing kids' game and show me some proof.
People like me may lack professional background in auto domain, but we have at least basic logic and will judge based on available info online, after all there are also so many pros out there in the public. That's why i want to hear technical analysis from Tesla circle ( the other side already enough ) and keep doubting,however some guys always reply that this must be the driver's fault. How could he be so sure about that?
I believe paradox will eventually appear from at least one side and hope i can find it myself.
Ms. Zhang has posted no evidence of a brake failure and refuses an independent examination of her car. As far as I can find, she have not even hired a mechanic to do a basic examination of the braking system (such that at least you can eliminate typical mechanical causes of brake failure, like a leak or air/water in the line or master cylinder, brake pad/discs being defective, brake booster pump failing or wiring contaminated, etc). All we have to go by is her claim the brakes failed (note she wasn't even the driver, her father was driving).

Tesla posted their evidence already that strongly suggests that this is simply Ms. Zhang's father speeding and/or not keeping enough following distance. Tesla can't really do anything further to determine if there really is a problem with her car's braking system, given Ms. Zhang refuses to any sort of examination of her car.

Tesla had sold more than 500k Model 3 already, and no reports in this forum of similar issues when the system is working normally (only one case of brake boost lost in a car with a failed electrical system which the car had lots of warnings above, but car appears to still be able to brake). So unless someone posts at least some evidence, most people here aren't going to believe the Model 3's brakes are defective. As others posted, USA operates under the assumption of "innocent until proven guilty." It's the accuser who has to provide evidence of guilt, not the defendant's job to prove themselves guilty (or not). It's hard to refute an argument where the only evidence the lady has is her word and nothing else. There are many possible causes of brake failure, and so far we have no details at all on the condition of the vehicle's braking system, so all the internet talk so far is just speculation.
 
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Electric Dream

Pilots the Millennium Milkfloat
Jul 21, 2016
1,682
2,759
UK
I can tell you now what the cause of this and other 'pedal misapplications' is. It's actually quite simple:
  • Drivers of EVs with regen are becoming less and less familiar with the brake pedal, how it feels and how to use it properly when required.
  • Drivers do maybe one emergency stop during their driving test and then rely on the car they drive thereafter to do the emergency braking for them with AEB etc.
  • Drivers are becoming less and less familiar with how a car works generally, how to operate it and what to do when things go wrong.
There's no way back from this because cars are only going to become more autonomous, so driving skills will wane and only enthusiasts will want to learn how to drive a car manually and with a degree of skill.

Some will say it's progress, some will say it's inevitable.
The result is the car is going to blamed for anything and everything bad that happens.
The owner will accept no responsibility.
This is the start of that.
 

sunjack

Member
Apr 20, 2021
28
2
Shanghai, China
I can tell you now what the cause of this and other 'pedal misapplications' is. It's actually quite simple:
  • Drivers of EVs with regen are becoming less and less familiar with the brake pedal, how it feels and how to use it properly when required.
  • Drivers do maybe one emergency stop during their driving test and then rely on the car they drive thereafter to do the emergency braking for them with AEB etc.
  • Drivers are becoming less and less familiar with how a car works generally, how to operate it and what to do when things go wrong.
There's no way back from this because cars are only going to become more autonomous, so driving skills will wane and only enthusiasts will want to learn how to drive a car manually and with a degree of skill.

Some will say it's progress, some will say it's inevitable.
The result is the car is going to blamed for anything and everything bad that happens.
The owner will accept no responsibility.
This is the start of that.
Is that what Elon wants?
 

skywalker2go

Member
Apr 26, 2021
13
-8
China
I'm only aware of 2 facts in this case. The guy was speeding and the woman is crazy. If there are more *facts* please share them with us.
I think what you described here should be called 2 assumptions in stead of 2 facts. But what i list below could be proved either by public paperwork or recorded videos and images.

1、Before the accident happened, Miss Zhang's family ( her parents, Ms. Zhang, and her 1-year-old niece ) were in the car. The accident happened at about 6 pm on the urban road. Her father was a truck driver with more than 30 years experience.
2、Ms. Zhang refused to accept Tesla's assigned third party for inspection. And Tesla did not admit any other third party's result.
One of these certificates provided by Tesla‘s assigned partner marked M3 as front wheel drive.
3、Ms. Zhang has tried to negotiate with Tesla for many times. Tesla promised to help resell the car to someone else. Ms. Zhang considered that to be immoral and refused.
4、After the protest, Tesla's VP declared in public "Never compromise", and "Some one must be behind Ms. Zhang", without providing any proof. Apologizes are issued later after the government made some comments.
5、Ms. Zhang has always demanded EDR info, especially brake pedal distance related data. Tesla did provide some data, but did not include the most critical pedal distance related info. No further response made.
As a comparison, another brand also encountered similar accidents, then they released full logs and detailed EDR info. Shortly after that the public stopped criticizing that brand.

Above are just parts of the facts available, I did not mention them before because i think they would make people emotional and also contribute little to the final analysis.
IMO, for a video that tends to tell the whole story, i think at least a few points above should be mentioned, otherwise people may think that Tesla belongs to the vulnerable groups, which is obviously not true, at least in China.
 

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