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AutoPilot decelerates too abruptly

Eric_L

Member
Feb 21, 2015
17
0
United States
It would be nice if we had some sort of way to adjust the deceleration range of the autopilot. For example - if you are manually operating the accellerator and approaching a stopped vehicle you would usually take your foot off the accelerator for a few seconds before applying the brakes, bringing the car to a gradual and comfortable stop. The Tesla AutoPilot does not; it waits until you are uncomfortably close then brakes immediately without coasting. It constantly makes me nervous because the time I would need to intercede if necessary is considerably reduced. The stop is not comfortable and gradual, it is somewhat abrupt; I can feel my momentum pulling me forward in the seat.

There would be alot of comfort in knowing that the Tesla is reading the stopped vehicle much sooner, as well as the literal comfort of a more gradual deceleration.
 

LetsGoFast

Active Member
Oct 13, 2014
1,329
101
Virginia
Believe it or not, this is actually significantly improved. Earlier releases of TACC braked even later and harder. I agree with you that they could still improve, especially when approaching stopped traffic.
 

Discoducky

P100DL, 2021 M3, 3 CT reservations and counting
Dec 25, 2011
3,590
4,997
My mountain
@Eric, what is your following distance set at? 1-7

As others have said, it has gotten better, but you might get some benefit by setting your following distance closer to 7.
 

zer0cool

Member
Apr 26, 2015
506
332
charlotte, nc
I personally think it's pretty good now. Is it as good as a human, no, but is it significantly better than even just a few months ago, yes.

I wouldn't call the stops now abrupt, but just slightly harder than I would do them, so I think it's good enough.
 

bancroftc

Member
Sep 21, 2015
179
10
Austin, TX
OP - I don't think TACC is designed for "approaching a stopped vehicle" under any circumstance (unless you were locked on to that vehicle to begin with, while it came to a stop). You wouldn't use TACC to approach a concrete wall at speed any more than you would a car stopped at a traffic light 1/2 mile up. I would guess that automatic emergency braking is handling that maneuver (slamming on the brakes at the last minute) rather than TACC. When you experience this, does your display show the car in front in red? If so, that's AEB doing the work. Unless I'm misunderstanding the scenario you outlined, you might need to adjust how/when you are using TACC.

My experience TACC speed adjustment has been pretty damn good. I've had numerous occasions where a car in the adjacent lane will "cut in" between me and the car I'm following while on TACC. While the new distance between me and the encroacher immediately becomes too close, TACC gently decelerates to reestablish the following distance I have set. My previous cars with adaptive cruise control would slam on the brakes and overreact. The only exception is when I'm following a car on TACC, and the car in front decides slow down to take a right turn. TACC seems to overreact in this case, trying to maintain the preset distance by slowing hard and unnaturally, well after the car has exited the road. So much so that I feel like it could cause issue with cars following me. Normally, you see a car turning right and you slow down gently and decrease your following distance accordingly to time their turn. TACC doesn't seem to have a good solution to this scenario yet.
 

David99

Active Member
Jan 31, 2014
4,850
7,026
Brea, Orange County
It's a very subjective thing. I personally drive very much looking ahead and decelerate slowly long before I need to stop (as long as I don't hold up traffic behind me). I try to use both acceleration and slowing down very gently overall. Auto Pilot definitely behaves more like an average driver would in normal traffic. I think most drivers would do what Auto Pilot does. Some drive more aggressive and to them Auto Pilot feels to defensive. It's really subjective.
What I noticed when I first drove with Auto Pilot was that it felt all wrong! The car would do things that I would not have done the same way. It slowed down too early or too late, it accelerated too slow here and then too much in another situation. The problem isn't that Auto Pilot does something wrong, it's just that the car does it different while we are still in the driver's seat. It feels just wrong. Once you get used to it and let it do it's thing, it's fine.
 

LetsGoFast

Active Member
Oct 13, 2014
1,329
101
Virginia
OP - I don't think TACC is designed for "approaching a stopped vehicle" under any circumstance (unless you were locked on to that vehicle to begin with, while it came to a stop). You wouldn't use TACC to approach a concrete wall at speed any more than you would a car stopped at a traffic light 1/2 mile up. I would guess that automatic emergency braking is handling that maneuver (slamming on the brakes at the last minute) rather than TACC.

It depends on your speed. It actually now handles speeds of say 35 and below reasonably well. At 50, it probably would go into emergency braking territory.

- - - Updated - - -

Oddly enough one time I was using TACC and the collision warning sounded!

The other day I was using autopilot and the lane departure warning sounded. I'm honestly sort of baffled and sort of amused by that.
 

S4WRXTTCS

Well-Known Member
May 3, 2015
5,537
6,289
Snohomish, WA
My biggest issue with TACC is it doesn't correct for the persons behavior in front of me.

If the person in front of me is smooth then TACC is generally smooth. Sure it could be a little more smooth, but it's not bad at least when comparing to other Adaptive cruise control systems.

If the person in front of me isn't smooth then it just transfers than non-smoothness to me.

It doesn't seem to have any way of adapting to the behavior of the person in front of me.
 

cbin97

Member
Feb 9, 2015
116
29
Orange County
I had the collision warning come on just yesterday in traffic while using TACC. The problem is the distance setting and the speed that's locked in. If I'm locked in at 70 and the car I'm following departs my lane when I'm at 55mph then due to the big gap in front of me before the next car, TACC speeds up to desired speed even though I can see that about 13 car lengths in front the traffic is slowing to a standstill.
 

robert774

Member
Mar 21, 2015
107
51
Houston, Texas
I have taken to cutting TACC when I see the car rapidly approaching a stopped or much slower vehicle, which slows my car due to regen braking. After a few seconds I re-engage TACC and the car follows normally. I agree this can and should be approved with software because I can see the car is tracking the car in front by its icon on the front console.
 

Lex

Member
Apr 23, 2015
805
318
Toronto, Canada
I remember washing my wheels and seeing more brake dust the more I used TACC... but I agree it seems smoother now (and now that it's colder I've instinctively taken to braking in case regen is kaput so I'm making them all dirty on my own too).

My biggest issue with TACC is it doesn't correct for the persons behavior in front of me... If the person in front of me isn't smooth then it just transfers than non-smoothness to me
Yes, but I prefer it reacting quickly so I'm not sure I see a problem here. But I am wondering if you have air suspension ? I found Autopilot not as crisp with the air. Maybe an opportunity for some adjustment settings and controls, hello TMC perhaps more settings for like EVERYTHING one day soon please ?

As for the collision alert, yep mine (set on medium) seems to have been self-triggered eg. on Autopilot during what seemed like normal operation and traffic circumstances, but I don't expect the system to be perfect. It can't be, it's made by humans :)
 
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bancroftc

Member
Sep 21, 2015
179
10
Austin, TX
I had the collision warning come on just yesterday in traffic while using TACC. The problem is the distance setting and the speed that's locked in. If I'm locked in at 70 and the car I'm following departs my lane when I'm at 55mph then due to the big gap in front of me before the next car, TACC speeds up to desired speed even though I can see that about 13 car lengths in front the traffic is slowing to a standstill.

I hate when this happens, but have come to keep an eye out for it. Very disconcerting to be accelerating towards a bunch of red brake lights up ahead! Just drove the whole family from Austin to Dallas this afternoon in my wife's Denali (ICE! gasp!) and used adaptive cruise control about 90% of the drive. It behaves the exactly same way, so that particular issue is not isolated to Tesla, FWIW. I did wave and smile at the Waco supercharger when I drove by.

Side note on our SUV - I almost crash it every time I drive it expecting regen to kick in when I let off the gas, only to coast rapidly forward and end up having to smash the brakes. Pretty much happens every time I drive it, particularly if it's been a while. I also pushed the overdrive button on the end of the gear shift (same place as the Tesla) to put it into park and scared myself when the car started to roll forward when I let off the brake. Relived that I didn't hurt anyone, I put it into park the correct way and then got out of the car and walked away, only to realize the engine was still running. WTF!
 

Plan B

Active Member
May 8, 2015
4,862
2,235
Portland OR
My biggest issue with TACC is it doesn't correct for the persons behavior in front of me.

If the person in front of me is smooth then TACC is generally smooth. Sure it could be a little more smooth, but it's not bad at least when comparing to other Adaptive cruise control systems.

If the person in front of me isn't smooth then it just transfers than non-smoothness to me.

It doesn't seem to have any way of adapting to the behavior of the person in front of me.

LMAO
 

Max*

Charging
Apr 8, 2015
6,670
3,719
NoVa
My biggest issue with TACC is it doesn't correct for the persons behavior in front of me.

If the person in front of me is smooth then TACC is generally smooth. Sure it could be a little more smooth, but it's not bad at least when comparing to other Adaptive cruise control systems.

If the person in front of me isn't smooth then it just transfers than non-smoothness to me.

It doesn't seem to have any way of adapting to the behavior of the person in front of me.

I know EXACTLY what you're talking about. It has actually gotten better recently, but it was bad. If I was in traffic and following someone who would constantly jerk his car, I would disable TACC because it would be horrible. If that person left me lane, and the guy in front of him is more relaxed, TACC would do a much better job.
 

Lex

Member
Apr 23, 2015
805
318
Toronto, Canada
I know EXACTLY what you're talking about. It has actually gotten better recently, but it was bad. If I was in traffic and following someone who would constantly jerk his car, I would disable TACC because it would be horrible. If that person left me lane, and the guy in front of him is more relaxed, TACC would do a much better job.
Again... air suspension ?
 

BertL

Active Member
Aug 19, 2015
2,018
1,573
Carlsbad, CA
Agreed that TACC still needs refinement applied to it's logic -- even at furthest following distance it does not come close to as smooth (non-emergency) stop using just accelerator regen as I would driving unassisted. My former Lexus with Radar Cruise Control was never jerky or seemed to transfer a bad driver's behavior in front of me to my vehicle running mid-to-furthest distance apart... the acceptable exception being one time my Lexus began an emergency stop because the guy in front slammed on his brakes in the middle of nowhere for an unknown reason going 70+.

IMHO though, my Lexus had a lot less variability to following distance (IIRC, only 3 settings) than MS does. I personally expect if I have TACC on, and have elected to essentially ride the guy's tail at setting 1, TACC is going to be more jerky and abrupt as speed increases given less distance and time to react -- but that would be my choice if I used setting 1 (that I never do). OTOH, if driving at setting 7 (furthest distance apart), there really isn't any reason why my state-of-the-art MS can't almost always react in a more refined way as it slows, stops and follows, as my now former and antiquated Lexus always did (well, it couldn't fully stop itself, but you hopefully get my drift).

VENT ON:
I am just hopeful that since TACC is still relatively new to Tesla in the last couple of major software drops, that Tesla (or Elon) has not already moved on to some other thing they find more interesting (I worry about that a lot), and in doing so keep TACC in it's almost-done state like so many things that could exit Beta, be so much better if Tesla prioritized further refinements, or just flat-out finished what they started: Media Player and USB support, Calendar, Nav Routing, Improved accuracy with Anxiety Mode pop-ups and waypoint charging redirection, etc. immediately come to mind -- many others being discussed in the 7.1 voting threads.
VENT OFF: (Thank you. I feel better now.) ;)
 

favo

P3D+ owner
Apr 5, 2012
1,043
1,140
Durham, NC
Sounds like they need to modify the TACC algorithm to allow a wider range around the set distance, especially when the set distance is at the larger end of the scale. I.e., have a larger slop factor for larger following distances (or use a percentage or whatever). If you imagine an elastic connection to the car in front, you want to set the max length and elasticity. I suppose they could present both as separate settings, but that might be too confusing for some folks.
 

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