But...if you are regularly using regen to nearly stop the car, you usually do not apply the brake until the last second when car is in creep mode.
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Sudden Unexpected Acceleration today
- Thread starter AZM3
- Start date
Dan203
Active Member
I don’t have one yet so can’t test myself, but what happens if you brought the car to a complete stop using regen and then pushed down on the shifter and enabled cruise? Would the car suddenly accelerate to try to get up to last used cruise speed? What if you did this and just lightly tapped the accelerator, would it accelerate to cruise speed then?
With cruise, you cannot activate it below (I believe) 25 mph. Where the cruise surprise comes into play, is when say you set cruise at 25 mph (for example) and then you get a speed sign saying that you can proceed faster but you use the accelerator to go faster. Finally your turnoff is coming up and you stop pressing the accelerator pedal and begin regen braking but at the cruise setting at 25 mph it will stop regen braking and feel like it is accelerating without pressing any pedals because it is resuming the low cruise setting. It can be a surprise. Just one type of surprise that I think some are experiencing. Yes, applying the brake pedal will cancel cruise but it might make someone think/feel unexpected acceleration occurred.
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lairdb
Member
The threshold is lower than you might expect, like two or three MPH. Below the nominal creep speed, IIRC. If you are braking toward zero and attempt to shift to the other direction in preparation to accelerate again, the vehicle will ignore the control input and will not give you any feedback that it did (other than not-changing the display.)
Sure you can. In fact, you can activate cruise at 0 mph. Steps to duplicate: come to a stop behind another vehicle. Put your vehicle in brake hold. Activate cruise.
You cannot set the cruise lower than 18mph -- but that's a different matter.
Well since I use creep mode, I never use brake hold so I have no experience with what you speak of.
Why not? I use creep and Hold.
Yes I often activate AP when in Hold in traffic.
Dan203
Active Member
I've experienced this same thing in my BMW with adaptive cruise control. Follow another car that is slowing down and the car will slow significantly below the set speed. But as soon as that car gets out of the way you get a burst of sudden acceleration that can be unexpected and unwanted. (like on an off ramp)
But this isn’t quite what I think is being discussed here. It is a problem, but not quite the problem that’s being discussed.
Daniel in SD
(supervised)
There's not really much to discuss about unintended acceleration. Without evidence to the contrary we have to assume that the driver pressed the accelerator when they thought they were pressing the brake. It happens with every make and model of car so it seems unlikely that it's a malfunction. Now that everyone drives automatic transmissions maybe they should just put another brake pedal for the left foot. If everyone learned to use a left brake pedal I bet there would be no more unintended acceleration.
Dan203
Active Member
If they can't figure out how to drive with two pedals, I don't think adding another pedal will make it any easier for them.
Dan203
Active Member
I think the idea is to move the brake over so that it's primary position is under the left foot. So you'd only ever use the right foot for accelerating and the left foot for braking,
Daniel in SD
(supervised)
You'd have to also have the brake pedal on the right too though!
Actually you'd have a big problem that people would learn to left foot brake and then get in a car without it and miss the brake pedal. It would probably be impossible to transition without causing more harm than good. I suppose everyone could just learn to left foot brake with the current pedal position (some people already do) but that seems like it would be uncomfortable.
Dan203
Active Member
I agree that two pedal driving with current position would be uncomfortable, but it wouldn't be impossible, so the transition from a new car, with the pedals set to left and right foot positions, to a "traditional" car wouldn't be impossible.
I recently heard this somewhere, but can't remember where. But essentially the quote was.... "continuing to do things a specific way because that's the way it's always been done is a bad idea". So if two foot driving is a better way for people to drive and would prevent accidents then maybe we should transition to it. It took me a while to get use to my ergonomic keyboard with the big split in the middle, but now I can type better than before and my wrists don't hurt. Maybe the same would be true for a car designed to drive with a foot on each pedal. I'm not in the auto industry or the highway safety industry so I have no data to back that up, but perhaps it's worth looking at. (maybe someone is, or has?)
Silicon Desert
Well-Known Member
You are probably right about that for some people. For me, not an issue.. I have always been a two foot driver because I learned to fly (two feet required) before I ever had a driver's license. When I get in a plane, both pedals are closer together and used for different reasons than in a car. For whatever reason, the usage change just comes naturally. So to me it is not uncomfortable at all, and not confusing, and I never miss the brake. Yet I can understand where it might be uncomfortable and a problem for some people.
I disagree! That 0.003% doesn't actually exist. It's 100%.
I engage it all the time in stop and go traffic from a dead stop.
I've had this happen but not to that degree, my Tesla recognizes it's on a ramp/curve and adjusts speed as necessary.
Don’t forget the cruise stalk!
I used to get unintended acceleration events in my classic S when I would engage the cruise stalk instead of the blinker. Always exciting as my P85 punched it while I was rounding a right turn. Out of curiosity, what do you think of this fellow’s data? https://www.autosafety.org/wp-conte...udden-Acceleration-Log-Data-What-It-Shows.pdf
Real accelerator pedal sensor data from the log file of a Tesla S sudden acceleration incident has been provided. After giving an explanation for how the data was obtained from the two accelerator pedal position sensors, the data was examined. It was concluded that changes in the accelerator pedal sensor output caused the sudden acceleration. The alternating peaks and valleys in the accelerator pedal sensor data appeared to show that the driver was stabbing at the accelerator pedal. This led Tesla engineers to conclude that the driver was the cause of the sudden acceleration. But the four valleys indicating that the accelerator pedal was released had a duration of one exactly second accurate to 0.1 second. This accuracy in the duration of four successive pedal release times could not have been caused by a human driver. Instead, the peaks and valleys in the output of the accelerator pedal sensor appear to have been caused by a thermally induced leakage current in the motor speed sensor, which is housed inside the hot drive motor housing, and which shares a common+ 5V power and ground with the accelerator pedal position sensor. An explanation of how this leakage current originates, and how it increases the output of the accelerator pedal position sensor while the accelerator pedal is released by the driver, was provided. The explanation reveals that the four identical pedal release times are caused by the +5V regulator powering the accelerator pedal and motor speed sensors going into reset at high temperature, turning off the sensors for a fixed time duration of exactly one second. While the motor speed sensor is turned off, the algorithms controlling the vehicle’s drive motor become unstable, causing the motor speed to increase without control. This causes sudden acceleration to occur without the driver pressing on the accelerator pedal. This explanation provides a testable theory of sudden acceleration in the Tesla S vehicle. The theory applies to all Tesla S and Tesla X vehicles as a result of commonality in the design of their traction motor/inverter assemblies.
That may become true at some point, but as long as there are still cars with mechanically operated throttle linkages there will still be mechanically caused unintended acceleration. (e.g. broken return spring). Not all that germane to a Tesla forum, I know, but it's important to keep an open mind.
Don’t forget the cruise stalk!
Out of curiosity, what do you think of this fellow’s data? https://www.autosafety.org/wp-conte...udden-Acceleration-Log-Data-What-It-Shows.pdf
Real accelerator pedal sensor data from the log file of a Tesla S sudden acceleration incident has been provided. After giving an explanation for how the data was obtained from the two accelerator pedal position sensors, the data was examined. It was concluded that changes in the accelerator pedal sensor output caused the sudden acceleration. The alternating peaks and valleys in the accelerator pedal sensor data appeared to show that the driver was stabbing at the accelerator pedal. This led Tesla engineers to conclude that the driver was the cause of the sudden acceleration. But the four valleys indicating that the accelerator pedal was released had a duration of one exactly second accurate to 0.1 second. This accuracy in the duration of four successive pedal release times could not have been caused by a human driver. Instead, the peaks and valleys in the output of the accelerator pedal sensor appear to have been caused by a thermally induced leakage current in the motor speed sensor, which is housed inside the hot drive motor housing, and which shares a common+ 5V power and ground with the accelerator pedal position sensor. An explanation of how this leakage current originates, and how it increases the output of the accelerator pedal position sensor while the accelerator pedal is released by the driver, was provided. The explanation reveals that the four identical pedal release times are caused by the +5V regulator powering the accelerator pedal and motor speed sensors going into reset at high temperature, turning off the sensors for a fixed time duration of exactly one second. While the motor speed sensor is turned off, the algorithms controlling the vehicle’s drive motor become unstable, causing the motor speed to increase without control. This causes sudden acceleration to occur without the driver pressing on the accelerator pedal. This explanation provides a testable theory of sudden acceleration in the Tesla S vehicle. The theory applies to all Tesla S and Tesla X vehicles as a result of commonality in the design of their traction motor/inverter assemblies.
Caveat, I did not read the whole thing.
It appears they do not understand that the accelerator pedal feedback are dual slope. One starts out near 5V and one starts near 0. As the pedal is pressed, one goes up and and goes down. In addition, the power feed itself is likely monitored by the system/ software. A lack of voltage to the pedal would definitely be caught by the software and not processed as a valid pedal input.
(other variants use two slopes that both increase, but even then, they are offset from the limits, so 0 is never valid (otherwise a disconnected pedal would not be detected))
In general:
If the system detected loss of pedal input, it should cut motor power, regardless of motor feedback.
I was not aware that the AC motors had an encoder on them, I always thought they used the ABS sensors. FOC control schemes do not require encoders.
Cirrus MS100D
Member
I had a crazy thought, hear me out:
All new cars automatically accelerate on their own at a linear rate and the ONLY pedal is the brake pedal. One. Big. Pedal.
Can’t have unintended acceleration unless of a total and complete failure of primary and backup braking systems! You modulate acceleration by using the brake pedal: Take the foot off the brake, accelerate like a P100D Raven. Slowly let the brake pedal come up, car starts to move at walking pace.
Done. Problem solved.
All new cars automatically accelerate on their own at a linear rate and the ONLY pedal is the brake pedal. One. Big. Pedal.
Can’t have unintended acceleration unless of a total and complete failure of primary and backup braking systems! You modulate acceleration by using the brake pedal: Take the foot off the brake, accelerate like a P100D Raven. Slowly let the brake pedal come up, car starts to move at walking pace.
Done. Problem solved.
