But that doesnt require any input .. the car will slow to increase the distance from the car in front as soon as it can do so (which means as soon as you release the accelerator). Try engaging CC when there is no car in front of you and see if it still does the slow down/speed up dance.
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Cruise Control still follows throttle pedal
- Thread starter CorneliusRox
- Start date
I think this behavior is intentional to allow the driver to remain in control of vehicle power/speed until the accelerator is completely released. More specifically, in situations where the cruise control set speed is significantly higher than your current travel speed, e.g. work zones or bad weather, this feature allows the driver to maintain current speed with the accelerator while dialing in the desired cruise control speed.
I remember a time where my car didn't behave this way and would immediately accelerate to the set speed upon activating cruise control. This was a problem when traveling significantly below what the car thought the set speed should be, like when going 45 in a work zone on a 60 MPH road or when trying to go slower than the speed limit in bad weather.
But yes - I agree that the current programming leaves a lot to be desired in terms of smoothness when engaging cruise control.
I remember a time where my car didn't behave this way and would immediately accelerate to the set speed upon activating cruise control. This was a problem when traveling significantly below what the car thought the set speed should be, like when going 45 in a work zone on a 60 MPH road or when trying to go slower than the speed limit in bad weather.
But yes - I agree that the current programming leaves a lot to be desired in terms of smoothness when engaging cruise control.
mikes_fsd
Banned
Yes, that is correct. But again it only applies if you're feathering the accelerator, the go pedal.
The slowdown is not drastic either it's like 1 mph difference. Almost feels like you're just letting off the accelerator.
If you punch the accelerator you will not recreate this scenario.
It literally can't work this way.
If cruise "held" a position that had nothing to do with speed, then when you went downhill, you'd speed up, and the vehicle would ignore this. If it holds a position, it also means you couldn't reduce the throttle position as it would ratchet up as you gave it more throttle. And there is no correct position for a given speed, as it depends on hills, winds, weight, etc. The car doesn't even have a throttle pedal position sensor in your explained case, so it's impossible to determine what is going on.
I think the issue with a Tesla is that if you let off quickly you hit regen, which means it slows down much faster than other cars and is more noticeable. I've never owned an automatic transmission car, and manuals act a lot more like an EV, so maybe that's the difference in experience. I've always needed to let off slowly to not encounter a jerk- and I still do in my 2010 BMW.
FirstInTown
Member
Yes, it DID literally work this way. The throttle got pulled tight and you were able to remove foot W/O a jerky feeling in the car. The cruise control was connected to the carb throttle at the same axis point as the cable from the foot pedal and they did a relatively smooth transfer. For hills and the like, to PID controller would release the cable abit as speed up. If you were still on the gas, of course you wouldn't slow down under car control.
I remember an add-on cruise system that was connected in series with the speedometer cable to get speed and a vaccum line to have 'power' and had a cable you connected to where the foot cable connected to the carb. The car year was 1974.
So, you turned on the cruise and slowly release the foot pedal to slow a bit (say 1-2mph, slowly) The cruise would pull it's cable tight until the car started to accel to the set point. At this point the PID loop in the controller would have enough integral gain to maintain this location, and the gains were tuned such that the speed back up of 1-2 MPH was not harsh.
You could very lightly rest your foot on the petal and feel the pedal go lower as the car went up hills and the cruise opened the throttle.
'Throttle by wire' cars, like the Volt have a smooth transfer from driver to car speed control. The Tesla is also 'throttle-by-wire' and is not smooth on that transfer. I contend it could be.
1. Car knows torque level when engage cruise, latch level.
2. Turn Cruise on,
a. disable regenerative braking from throttle position temporarily during this transition.
b. as long as pedal RELEASED over say next 2 seconds AND car required torque doesn't decrease, hold torque as release foot.
b1. If torque demand increases, add torque even at same throttle level automatically.
This allows smooth removal of foot.
FirstInTown
Member
So it's a 'feature'? I can see where could use to maintain a slower speed, but I just tap the X down speed to get setpoint closer to what I want, just like DECEL button in other cars.
If it is a feature, OK, I guess. But agree, it is not a smooth transition and could be.
I've noticed this issue on my S100D recently. I wonder if a recent software update changed things. I don't remember having this jerkiness issue years ago.
In the past, if I was going slower than the set cruise speed, the car would speed up when I would engage TACC. If I was going faster than the set cruise speed, it would gradually slow down to the set speed if I removed my foot from the accelerator. Now when I try to set it, it sometimes slows down to several miles per hour below the set speed before accelerating back up to the set cruise speed.
In the past, if I was going slower than the set cruise speed, the car would speed up when I would engage TACC. If I was going faster than the set cruise speed, it would gradually slow down to the set speed if I removed my foot from the accelerator. Now when I try to set it, it sometimes slows down to several miles per hour below the set speed before accelerating back up to the set cruise speed.
mikes_fsd
Banned
Want to clarify something.
There is only Adaptive Cruise Control in Tesla's (TACC) there is not dump cruise control in these cars (at least not since 2014).
Not true.
TACC is part of AP. Cars sold 2014-2019 could be bought without any AP, and thus have non-aware cruise. It's even more complex in non-US reigons.
But remember, TACC is "beta" (just like everything else in AP and auto wipers) so nobody has any right to complain about it, you know what you were buying, right?
FirstInTown
Member
Did a 500 mile trip this weekend, lots of 2 lane 55-65 MPH roads, so played with this. It's weird, as there are times I CAN lift foot and does just like it should, no slow down as remove foot. So played with it to see pattern.
On s/x pull cruise lever 1= TACC, 2x = FSD. Not sure how to active on 3/Y, so up to you to you to translate this.
-Pull 1x for cruise and right way, lift foot. Don't wait a second or 2 like I was normally doing.
-Be AT speed will be setting cruise at. Ex, if setting at 62 mph as displayed on speedo, be at that speed to keep car from having to speed change.
Doing these 2 things and the speed transfer to CAR control was very smooth.
On s/x pull cruise lever 1= TACC, 2x = FSD. Not sure how to active on 3/Y, so up to you to you to translate this.
-Pull 1x for cruise and right way, lift foot. Don't wait a second or 2 like I was normally doing.
-Be AT speed will be setting cruise at. Ex, if setting at 62 mph as displayed on speedo, be at that speed to keep car from having to speed change.
Doing these 2 things and the speed transfer to CAR control was very smooth.
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