Where do you keep your foot?

[kiwi]

On a long drive over the weekend I had yet another case of phantom braking.
It was in reasonably busy but fast traffic on a main (multi-lane) motorway. I had to hit
the throttle quickly because of the cars close behind. This is V9 - 42.2 BTW.
I'm pretty sure it was braking and not just slowing via regen, it seemed very strong.

I was wondering - where do you leave your foot when on a long autopilot trip?
I often have to brake because the autopilot doesn't deal with merging, but these
I can see a long way in advance and so there's plenty of time to react.
I occasionally have to hit the throttle because of phantom braking, and
for those I have to be quick because of the cars behind.

Its pretty uncomfortable to leave your foot hovering over the accelerator, although I
did that for a while after the last one.

 

[Aljohn]

The only times I have had sudden braking is approaching a turn where the X thinks adjacent traffic lane is in my lane (AP1).
I keep my feet on the floor near the peddles -- never hovering above them. Mainly be cause hovering, as you point, out is uncomfortable and tiring. Secondly one can inadvertently rest on the peddles -- brake or acceleration. If you are not slowing sufficiently approching slowing traffic, check the rotation of the "cruise" stalk and see how many car lengths is set -- I use 3 as a comfortable distance. 1 and 2 are a little too close for me. Conversely, anything over 4 car lengths seems to allow (unscientifically) cars squeeze in. So my comfort zone is 3 car lengths. To your issue -- I seldom have to accelerate manually. I set the speed at a comfortable speed for me to travel and allow the autopilot to reduce speed from there. By comfortable speed I mean the speed at which I would drive manually for given road and traffic conditions.... The X is far more capable than my reaction time and sight distance. If autopilot is faster than I am personally comfortable, I feel that I tend to try to brake more often. Conversely, too slow requires acceleration not to impede traffic. Try to find a speed and distance where you are comfortable with traffic conditions. Relax, set a speed at which you would manually drive and enjoy Autopilot.

 

[kiwi]

You are lucky to never have "phantom braking" as it is known.
The car suddenly decelerates hard in the middle of flowing traffic, in this case
on a dead straight piece of road. That creates some excitement and
consternation from the cars behind you Rapidly hitting the accelerator
is definitely required.

I hear your point about setting a gap you like - in my case its a 4.

 

[Skotty]

I keep my foot attached to my leg at the heel.

 

[kavyboy]

Its pretty uncomfortable to leave your foot hovering over the accelerator, although I did that for a while after the last one.

I don't get phantom braking (AP1 - maybe that makes a difference) but I keep my foot over the accelerator anyway because that's been it's home while driving for a few decades. If I take my shoes off, then it's a light-enough touch to not actually accelerate, plus it's pretty comfy. My old-style yacht floor is a great shoe holder.

 

[animorph]

I have had plenty of phantom braking, and it is handy to hover my foot over the accelerator just for that. But the main reason is that that's where I expect my foot to be normally. My reflexes to the brake are practically automatic after so many years, I've sometimes braked before even thinking about it. If my foot was anywhere else my reflex reactions would be all wrong, I'd have to think about it, might hit the brake instead of the accelerator or might even hit the accelerator instead of the brake. So my foot remains over the accelerator and all my learned automatic responses are still valid.

 

[kiwi]

@kavyboy I've driven AP1 - I envy your smoothness and predicability.
It felt like places AP1 failed, it would do so more gracefully.

@animorph I'm beginning to think you are right. I've normally left my foot on the
ground in front of the accelerator (most comfortable) - and when braking hits, I jump my foot onto the
accelerator fast, and its never a smooth action. Its practically impossible to
gently apply acceleration when you are rapidly bringing your foot to the throttle
to stop that truck behind you from crushing you. I end up over-compensating
and my passengers go from lurching forward due to sudden braking to lurching
back from full throttle. Fun!

 

[Aljohn]

Interesting discussion on "phantom braking. I can only speak of AP1. A few clarifications: 1. I only use Auto Pilot on Interstate highways -- never in constructions zones or on surface streets. 2. I keep the "offset" setting at zero (0). 3. If my X (AP1) is slowing because of slowing traffic and I hit the accelerator, I get dash warning immediately saying the accelerator is pressed. The X allows me to control, but the warning is quite prevalent. 4. The only time I have had phantom braking is in the right curve where the on adjacent lane traffic was interpreted as a impending collision -- lots of warning sounds -3 beeps and hard braking (RED Dash). It sounds like you are describing a more subtle slowing type braking, which I have never experienced in 3 years. @kiwi -- try reducing the distance to 3 car lengths.... it appears to me that Tesla errs on the side of caution, so 3 car lengths is actually longer. Possibly 4 is too great???

 

[BigMskiman]

I had a significant phantom breaking while on AP thru rolling hills single lane hwy (going south on 128 b4 Cloverdale) , but only once, right at a hill crest. I know this was an earlier AP problem, maybe lane lines lost, but was not expecting anything like this.

old |v2018.40 |AP2,PUP|
new |v2018.42.2|AP2,PUP|

 

[kiwi]

@Aljohn, I'll try reducing the gap.

For me, phantom braking is relatively rare - maybe once or twice every couple
of weeks when I'm doing more motorway/long distance driving (my normal commute is via
back streets and I can't use AP at all). But it does happen on straight divided motorways
and straight main streets, and when it happens it is quite a shock. I've had it happen when
there was nothing in front of me but clear, empty road (no road works, bad paint etc).

In the old days (12 months ago) it would happen every time I went under a bridge - fortunately
that one has been resolved.

 

[Aljohn]

@kiwi Good luck. Keep us posted, so to share with others.

 

[kiwi]

Will do. Sadly (for me) my wife is taking the MX away for a weekend trip.
I'm relegated to the Leaf. .

 

[Aljohn]

Will do. Sadly (for me) my wife is taking the MX away for a weekend trip.
I'm relegated to the Leaf. .

Ah.... I am sure she is sorry for you (not). I was watching a video of a 3 traveling in Nav-on-Auto Pilot, and the driver acknowledge that phantom braking was common with long shadows, especially during early (rising) and late evening (setting) sun light. Therein may lie and answer. I am retired and seldom drive in those conditions.

 

[hiroshiy]

In my experience, phantom braking happens frequently at locations where there are overhead objects or narrow lanes with curves where long trucks and trailers cross lane markings toward the car. For me it is sort of predictable so I usually prepare for it.
Sometimes it brakes when you have the sun directly in front of you.

I usually have my right foot on the floor near the accelerator in AP and cancel AP when phantom braking happens, so that Tesla would know there was an AP issue at that spot.