Speed Limiter "logic" - Jaguar I-Pace EV400 Forum
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post #1 of 9 (permalink) Old 04-29-2019, 01:43 PM Thread Starter
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Speed Limiter "logic"

So I need help here. I am relatively tech savvy, not a total idiot, yes the function of the speed limiter is a mystery to me. So when I just turn it on and its orange it pretty much tells me I am going too fast and tries to prevent me from speeding up at ANY speed (even when it shows the speed limit detected at 50 it complains at 35). And then when its green for auto speed it doesn't seem to always drop the speed when the speed limit changes. I understand it won't go up, but doesn't always go down. And btw it ALWAYS turns on when you set cruise.

So I am not even sure what action causes which mode to turn on (orange or green), and I don't understand if its just not working properly for the non cruise mode.

Anyone else? Any tips? Insights?
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post #2 of 9 (permalink) Old 04-29-2019, 07:53 PM
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I accidentally turned it on when I was first attempting to try the cruise control.



It definitely kept me from accelerating past the speed I had 'set' for it (not on purpose), until I gave it a lot of pedal.


I gave up on trying the cruise control until I finally realized I had toggled on the speed limiter as I could tell by the graphic light on the dash display. It's toggled on/off with the button by the set and +/- control. I suspect you also have it accidentally on. If so, turning it off returns the set speed to the cruise control function instead of the set speed limit.

2019 I-Pace 400EV HSE First Edition
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post #3 of 9 (permalink) Old 06-26-2019, 03:57 PM
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Quote:
Originally Posted by epirali View Post
So I need help here. I am relatively tech savvy, not a total idiot, yes the function of the speed limiter is a mystery to me. So when I just turn it on and its orange it pretty much tells me I am going too fast and tries to prevent me from speeding up at ANY speed (even when it shows the speed limit detected at 50 it complains at 35). And then when its green for auto speed it doesn't seem to always drop the speed when the speed limit changes. I understand it won't go up, but doesn't always go down. And btw it ALWAYS turns on when you set cruise.

So I am not even sure what action causes which mode to turn on (orange or green), and I don't understand if its just not working properly for the non cruise mode.

Anyone else? Any tips? Insights?
According to the manual the limiter only forces the vehicle to stay below the selected speed perhaps as a method for the driver to not accidentally go over the limit. The adaptive speed limiter is supposed to read speed limit signs and keep the driver under the limit even as the limit changes.

I think it's a useless feature that confused me too the first time I wanted to engage the cruise control.
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post #4 of 9 (permalink) Old 06-26-2019, 05:08 PM
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Speed limiter: This is best activated by driving the maximum speed you want to be limited to, press the LIM button, then toggle the speed control (silver thing) to the SET+ position. That is now the speed to which you can drive before the car complains of you speeding.

Once you've done that, you can increase/decrease the limit in 5 mph increase by press and holding the speed control up/down. A quick toggle will adjust it 1 mph increments.

The CANCEL button will cancel it. RES (push in on silver thing) resumes its operation.

Adaptive speed limiting: Press the LIM button. If speed limiter is displayed, press the CANCEL button. Toggle the silver thing to the SET+ position, or press in on it (RES). This will activate the adaptive speed limiter.
You can use the RES to increase/decrease the rate of acceleration/deceleration has it accelerates/decelerates.

CANCEL will cancel it and RES/SET+ will resume it. Use the SET+/- to adjust the detected speed if needed.

Adaptive cruise control (if the car is so equipped): Without LIM lit up, activate by pressing the speed control to SET+. LIM will light up green. Use the buttons to the side of the silver thing to increase/decrease the gap allowed.

CANCEL will cancel it and RES will resume. SET+ will reactivate it too at whatever speed you're driving at the moment.

The brake pedal can also be used to cancel any of these.

As for speed sign recognition, it doesn't do too well in school speed zones since it has no idea if the speed applies at that time of day, or other conditions. Signs around here say "School speed zone during restricted hours." I've never found an official definition of "restricted hours." It also does recognize when the zone ends.

It has also mistaken an off ramp speed limit for the speed limit of the main highway. That could cause a catastrophic accident with someone close behind in a 70mph zone and it suddenly decides to do 45 (or less).

That's why I don't use adaptive speed control but I do use adaptive cruise control.

More information, including limits of capabilities, in the owner's manual and iGuide.

Last edited by Ayepace; 06-26-2019 at 05:10 PM.
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post #5 of 9 (permalink) Old 06-26-2019, 05:25 PM Thread Starter
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@Ayepace : thanks it is clear as mud! Not your post but the various modalities and uses for the EXACT same button where the sequence of what you do determines what you get. It is really poor design imho.
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post #6 of 9 (permalink) Old 06-26-2019, 09:38 PM
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I totally agree. Three options using the same buttons (that have to be pressed in a specific sequence) but only one is active at any given time, or all are off.
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post #7 of 9 (permalink) Old 06-27-2019, 03:30 AM
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One thing I've noticed about the automatic speed limit display is that it only changes as of passing the sign. I guess that is a perfect performance, but I wonder how it happens. Side camera viewing, or would it be a speed/distance calculation? The former, probably.

2019 I-Pace 400EV HSE First Edition
Corris Grey - Ebony/Ebony
Suede Headliner
Fully Extended Leather/Ash Wood Trim
Heads-Up Display/Four-Zone Climate
20" Wheels/Rubber Mats x5
Delivered 2/22/19
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post #8 of 9 (permalink) Old 06-27-2019, 06:34 AM Thread Starter
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Originally Posted by LauderdaleFE View Post
One thing I've noticed about the automatic speed limit display is that it only changes as of passing the sign. I guess that is a perfect performance, but I wonder how it happens. Side camera viewing, or would it be a speed/distance calculation? The former, probably.
All cars I have seen that have sign recognition delay “activating” the display until you pass by the sign. You are probably correct that it is a guess on when to kick it by distance.
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post #9 of 9 (permalink) Old 06-28-2019, 10:55 PM
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Originally Posted by LauderdaleFE View Post
One thing I've noticed about the automatic speed limit display is that it only changes as of passing the sign. I guess that is a perfect performance, but I wonder how it happens. Side camera viewing, or would it be a speed/distance calculation? The former, probably.
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Originally Posted by epirali View Post
All cars I have seen that have sign recognition delay “activating” the display until you pass by the sign. You are probably correct that it is a guess on when to kick it by distance.
The cameras being used for this have a focal length and field-of-view known to the developers of the software. This is aided even further by the car having two cameras that may be providing a stereoscopic view, making the problem even simpler since with stereo vision the distance estimate is even easier. I don't know if the car is using stereo in the case or not, but even without stereo, the car can precisely calculate its distance to objects it identifies (like the.sign).

Combined with the known speed of the car and the change of observed angles to the sign as each video frame arrives, the car can very accurately calculate the position of and distance to the sign. This technique is known as SLAM (simultaneous localization and mapping). All newer mobile phones can do this as well. With this information the software can use fairly straightforward trigonometry to calculate exactly when the car passes the sign. In case you wonder, I develop augmented-reality apps for the iPhone and use these kinds of calculations regularly to determine the placement and orientation of objects in the camera's field of view.

You might notice when moving at low speed the car warns you of obstacles to the side even though there are no parking sensors on the side. And if you stop, it tells you that it will start reporting side obstacles once the car starts moving again. This is because it is uses the cameras under the mirrors to estimate the distance just like I described above... and without movement it can't figure out the distance with just a single camera on each side. Once you move and the angles start changing, then the distance can be calculated.
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Last edited by StormRune; 06-28-2019 at 11:03 PM.
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