5 ms·

While we're on the subject of maps-related bugs, I was recently borrowing a new Tesla Model Y and took it on a RORO ferry. After the crossing, the car’s GPS was

While we're on the subject of maps-related bugs, I was recently borrowing a new Tesla Model Y and took it on a RORO ferry. After the crossing, the car’s GPS was convinced I was still at the port where I had departed from. I restarted it a couple of times, but nothing. I drove off using Waze on my phone instead of the car's navigation. The map on the car kept moving relative to the direction I was driving, so the navigation was showing me driving into the sea and eventually started complaining that it would be impossible to find a charger. Approximately 5 hours later, just as I was about to arrive, the car finally managed to figure out my correct location. Exciting trip, not a huge fan of Teslas, but their charger planning is really nice. It was very unpleasant to suddenly lose it. I just genuinely wonder how such a bug can actually occur, surely you'd update the GPS fix more often than every couple of hours. Hard to imagine the car just suddenly couldn't get a GPS fix for hours either. But if it did somehow totally lose the ability to use GPS, the car must have a pretty good dead reckoning system given how well it was responding to my changes in direction. On a vaguely related note, driving 3000 kilometers through Europe in an electric car was surprisingly nice. Certainly didn't affect the length of the trip nearly as much as I'd have expected, but it was certainly super annoying to try and figure out the optimal rate of travel on the Autobahn. Charging at Tesla's supercharges was vastly more expensive than I expected, the "fuel" costs weren't much lower than what you could easily reach with a diesel car.

roywiggins 10mo ago
Possibly it was using WPS keyed to the ferry's WiFi and didn't consider the possibility that the ferry itself could move out of where it was registered (ie, the port)?
- monerozcash 10mo ago
  I drove away from the ferry and passed lots of WiFi APs on the way, presumably it should have figured out the new location pretty quick with WPS.
  - kijin 10mo ago
    Perhaps the car is programmed to ignore all external signals for a while if it detects significant disagreement for a prolonged time, as might have happened if it had access to both WPS and GPS during the ferry ride. In such cases it would be safe to assume that something is being spoofed, and fall back to INS.
Liftyee 10mo ago
I wonder if it's using a compass and odometry (distance) with dead reckoning. A strange choice when GPS is available, but it would account for the map moving in the car's direction and it not changing locations when it moved without rolling (ferry).
- billyjmc 10mo ago
  Almost certainly. GPS is not only easily jammed, but easily spoofed. If the car believed GPS instead of its own eyes, so to speak, then there’s significant potential that you’d see glitches more often. It could also be something of a safety risk when using its self-driving capabilities.
  - morning-coffee 10mo ago
    Makes me wonder why there isn't a UI feature within easy reach to let the user drag a pin on a map and tap "I know I'm here right now"... and if that agrees with where GPS also indicates, let's it reset its notion of "I must be getting spoofed right now" thoughts in addition to calibrating other notions of current location.
- bragr 10mo ago
  In addition to sibling's comments about jamming and self driving safety, there are many driving situations where there is no or poor GPS reception: tunnels, double deck bridges, double deck freeways, underpasses, urban canyons, actual canyons, etc. Also regional problems. The GPS constellation is in a 55° inclination, so if you are north of ~55N, or south of ~55S, you need a clear view of the southern/northern sky, respectfully, for reception, since there will be no overhead satellites.
stockresearcher 10mo ago
I had a Volvo XC90 that “jumped” off the interstate and onto a parallel mountain road east of Knoxville. It did its best to track along those roads and somehow made its way into North Carolina. But even when I was back in Chicago, it was still stuck in NC trying to find a way off those mountain roads. Dozens of on/off cycles did nothing. I disconnected the battery overnight and that didn’t work. At the next service appointment, the dealer had to do a full firmware reset to wipe the memory and get it working again. It amazed me that Volvo programmed an SUV to disbelieve that it could ever actually leave a road.
- kijin 10mo ago
  My dad used to have a crappy aftermarket GPS in his car that did the same thing. It would get lost dozens of miles away, and then hundreds of miles away. The explanation I found online at the time was that a GPS receiver needs to download data about the exact orbits of all GPS satellites from time to time. Satellites slowly lose altitude and change their orbits. Up-to-date information is constantly broadcasted by every satellite, but it takes about 15 minutes for a device on the ground to download this dataset. Most GPS devices do this automatically whenever they get the chance. But if your GPS is somehow unable to stay online for 15 consecutive minutes (bad firmware, faulty memory, tunnels, underground parking lots, etc), it will be relying on increasingly outdated info and drift far off its actual location.
  - pbmonster 10mo ago
    There's no way a modern smart phone or car relies on those ephemeris transmissions. They all just get it from the internet, which takes less than a second. That's one of the reasons why a smart phone has a reliable GPS fix basically instantly after being booted up, while old-school offline GPS units needed minutes to get a fix.
  - malfist 10mo ago
    _deleted incorrect statement_
    - 10mo ago
technothrasher 10mo ago
I remember cars in the early 2000's doing this. Haven't seen that behavior in years.
bragr 10mo ago
My guess would be: 1. Car entered ferry, loses GPS 2. Car entered dead reconning mode used for tunnels and such 3. Car left ferry, acquired GPS Then either: 4a. Location via dead reconning vasty disagreed with GPS because the car doesn't know about the ferry's movements, triggering some kind of failsafe. Or: 4b. There's just a plain old bug in the condition to switch back to GPS and maybe people haven't noticed because you don't get as badly desynced in a tunnel. >the car must have a pretty good dead reckoning system Yeah all the pieces are there: accelerometers and gyros for stability control, compass for navigation, and the wheel speed sensors give you exact distance traveled.
- toast0 10mo ago
  My local roro ferry drops you off pretty close to downtown. If you don't get a good fix as you get off the boat before you get into the urban canyon, satnav is pretty hopeless for a few minutes. Doesn't usually take 5 hours to figure out where it is though. At least not on my vehicles, even the one that's always getting confused.
- raverbashing 10mo ago
  It probably doesn't do dead reckoning even in tunnels And maybe the system sucks to get the GPS almanac if badly desynced
  - DonHopkins 10mo ago
    TomTom's have for at least 15 years or so. They have accelerometers to measure the motion when cut off from the GPS satellites. I worked there, knew the guy who developed it, and saw him give a presentation about it.
    - rob74 10mo ago
      That's cool... so I guess this works something along the ways of "calculate the speed via GPS before entering the tunnel, and then try to update this speed using the data from the accelerometer while in the tunnel"? Because as long a the car is moving at constant speed in a straight line, the accelerometer shouldn't register anything...
kbutler 10mo ago
Looks like others have reported similar issues. Entering a navigation route may help? https://teslamotorsclub.com/tmc/threads/map-location-and-routing-after-eurotunnel.335549/page-2?utm_source=chatgpt.com https://teslamotorsclub.com/tmc/threads/map-location-and-rou...
- monerozcash 10mo ago
  > Entering a navigation route may help? Didn't work for me.
somenameforme 10mo ago
A practical issue is that GPS can be spoofed relatively easily. If autonomous driving became a thing, and ubiquitous, with vehicles that prioritized remote over local consistency, then a single GPS spoof could cause some interesting things to happen. This is probably a concern that does drive decisions, at least to a degree. It creates a weird scenario where you kind of need to trust GPS, but you simultaneously also can't treat it as authoritative. OTOH creating a dumb user experience for a fairly common scenario, to try to preempt a hypothetical scenario is probably not a great idea. A fun problem to think about, though it may be completely unrelated to this issue.
- malfist 10mo ago
  If it becomes common place, spoofing is easy to counter. Directionality and parallax of the signal is enough to figure out the true signal, all it requires is an additional antenna. This won't prevent jamming, that requires a different mechanism, but spoofing should be prevented.
- dlcarrier 10mo ago
  I do hope self-driving software works out a better system, before it becomes common place. Autopilot has been incorporating GPS in aviation for decades, and it's still surprisingly common to have major problems when a loss of GPS occurs. The Phenom 300 jet can't fly straight without a valid GPS signal: https://news.ycombinator.com/item?id=12519629 https://news.ycombinator.com/item?id=12519629 Every swept-wing jet has a tendancy to enter a positive feedback loop of rolling and yawing, called a dutch roll, when flying at altitude, so even when not using autopilot, an active system is needed to fly straight and level. If the Phenom 300 doesn't have a valid GPS signal, that system fails.
pjsg 10mo ago
I suspect that my Tesla adjusts its location based on dead reckoning after losing GPS lock except that it assumes that I'm driving forwards. I.e. If I reverse out of my garage, then the map ends up in the wrong place and now I'm driving parallel to the road!
tgsovlerkhgsel 10mo ago
As you're mentioning a RO/RO ferry, recently, and Europe... are you sure you weren't in a GPS-denied environment, where the car (correctly) detected that GPS was jammed or spoofed and ignored it?
- monerozcash 10mo ago
  It was further west than you typically see significant GPS jamming, and GPS on other devices was fine.
jwr 10mo ago
> On a vaguely related note, driving 3000 kilometers through Europe in an electric car was surprisingly nice. Having done a number of multiple-thousand km trips in Europe in an EV (not a Tesla, nobody buys those anymore) — it's amusing how non-EV muggles think this is somehow an ordeal. It's just fine! There are drawbacks: you do have to use your brain and plan ahead more than you do when burning dinosaurs. But I found that the 20-30 minute stops every 2h really improve how I feel after a day or two of driving. Agreed about prices: there is gouging going on with some crazy margins. When charging at home, an EV is 2-4x less expensive per km than a gasoline-powered car, but when fast-charging on a road trip the cost of energy is nearly the same.
- SoftTalker 10mo ago
  [flagged]
  - namibj 10mo ago
    As a citizen I wish cars had similar driving break requirements as trucks do: mandatory 30 minutes break after 4.5 hours, 9-ish hours per day, minimum 9~11 ish hours break between driving days. Such minimum reasonable rest is what keeps you from killing innocents with your 2-ton weapon/tool.
  - jwr 10mo ago
    No need to get agitated. Some people enjoy sitting in the car for multiple hours, some people don't. I found it changed for me as I got older. However, about those 20 minutes — this, again, is a misconception. Stop at a busy rest area or a gas station and actually start your stopwatch. If you are a single male, it might take you shorter. If you are with a family, 20 minutes is pretty much the minimum.
    - DANmode 10mo ago
      Really depends on the air quality inside (and indeed outside) the car.
- zamalek 10mo ago
jonathan7977 10mo ago
One hypothesis I can offer is that your car could not, for whatever reason, use assisted gps to download the almanach which relies on mobile networks. Gps devices that download the almanac via gps itself can take up to twelve hours (in higher latitudes i think)!
- namibj 10mo ago
  It doesn't just become invalid; almanac is good enough to use for satnav for over a day.
kec 10mo ago
Civilian GPS (as in, the DoD’s Navstar) alone isn’t accurate enough to actually place you on a specific road. To compensate, auto navigation systems will snap you to the nearest road parallel to your current heading. Tesla likely didn’t consider the edge case of ferries and other off road situations in their mapping software and you hit some corner case bug.
- FireBeyond 10mo ago
  This used to be true, but the DoD turned off "selective availability" (the intentional degrading of the civilian signal) back in 2000, and the current generation of satellites do not have the capability (https://www.gps.gov/selective-availability https://www.gps.gov/selective-availability). What they do have though is a separate, encrypted, military broadcast that can be used for those purposes (I think the plan in those situations is to turn off civilian GPS entirely - but I think that there's no reason for that, now, due to the other navigation systems like GLONASS).
  - kec 10mo ago
    Even without selective availability gps is only accurate to within about 30’ in normal urban conditions which is more than enough to punt you over to a side street without heuristics on top.
    - everfrustrated 10mo ago
      Your device will use a lot more than the Navstar constellation to get a position these days.
testing22321 10mo ago
My farming GPS does this every time I ship it with my vehicle to a new continent. I always figured it has some code to get a quick location, and it assumes that location is very close to the last time it got a sat lock. I just ignore it for the first day, then it comes good.
pjdesno 10mo ago
Back in the days of MapQuest there was a (usually) very good site called mapsonus.com, but it evidently had one of the ferries that crossed Boston Harbor in its map as a zero distance link. Since it was offline, the bug was obvious although a bit frustrating - you had to put in multiple waypoints to make it forget its urge to send you on the ferry to Hull when you were trying to get to parts of the South Shore.
barnas2 10mo ago
>On a vaguely related note, driving 3000 kilometers through Europe in an electric car was surprisingly nice. I did 2 cross country road trips here in the US (~5000mi/8000km total) and had a similar experience. The nav's automatic charger routing did a great job, and we had 0 issues with charging.

roywiggins 10mo ago

Possibly it was using WPS keyed to the ferry's WiFi and didn't consider the possibility that the ferry itself could move out of where it was registered (ie, the port)?

monerozcash 10mo ago
I drove away from the ferry and passed lots of WiFi APs on the way, presumably it should have figured out the new location pretty quick with WPS.
- kijin 10mo ago
  Perhaps the car is programmed to ignore all external signals for a while if it detects significant disagreement for a prolonged time, as might have happened if it had access to both WPS and GPS during the ferry ride. In such cases it would be safe to assume that something is being spoofed, and fall back to INS.

Liftyee 10mo ago

I wonder if it's using a compass and odometry (distance) with dead reckoning. A strange choice when GPS is available, but it would account for the map moving in the car's direction and it not changing locations when it moved without rolling (ferry).

billyjmc 10mo ago
Almost certainly. GPS is not only easily jammed, but easily spoofed. If the car believed GPS instead of its own eyes, so to speak, then there’s significant potential that you’d see glitches more often. It could also be something of a safety risk when using its self-driving capabilities.
- morning-coffee 10mo ago
  Makes me wonder why there isn't a UI feature within easy reach to let the user drag a pin on a map and tap "I know I'm here right now"... and if that agrees with where GPS also indicates, let's it reset its notion of "I must be getting spoofed right now" thoughts in addition to calibrating other notions of current location.
bragr 10mo ago
In addition to sibling's comments about jamming and self driving safety, there are many driving situations where there is no or poor GPS reception: tunnels, double deck bridges, double deck freeways, underpasses, urban canyons, actual canyons, etc. Also regional problems. The GPS constellation is in a 55° inclination, so if you are north of ~55N, or south of ~55S, you need a clear view of the southern/northern sky, respectfully, for reception, since there will be no overhead satellites.

stockresearcher 10mo ago

I had a Volvo XC90 that “jumped” off the interstate and onto a parallel mountain road east of Knoxville. It did its best to track along those roads and somehow made its way into North Carolina. But even when I was back in Chicago, it was still stuck in NC trying to find a way off those mountain roads. Dozens of on/off cycles did nothing. I disconnected the battery overnight and that didn’t work. At the next service appointment, the dealer had to do a full firmware reset to wipe the memory and get it working again. It amazed me that Volvo programmed an SUV to disbelieve that it could ever actually leave a road.

kijin 10mo ago
My dad used to have a crappy aftermarket GPS in his car that did the same thing. It would get lost dozens of miles away, and then hundreds of miles away. The explanation I found online at the time was that a GPS receiver needs to download data about the exact orbits of all GPS satellites from time to time. Satellites slowly lose altitude and change their orbits. Up-to-date information is constantly broadcasted by every satellite, but it takes about 15 minutes for a device on the ground to download this dataset. Most GPS devices do this automatically whenever they get the chance. But if your GPS is somehow unable to stay online for 15 consecutive minutes (bad firmware, faulty memory, tunnels, underground parking lots, etc), it will be relying on increasingly outdated info and drift far off its actual location.
- pbmonster 10mo ago
  There's no way a modern smart phone or car relies on those ephemeris transmissions. They all just get it from the internet, which takes less than a second. That's one of the reasons why a smart phone has a reliable GPS fix basically instantly after being booted up, while old-school offline GPS units needed minutes to get a fix.
- malfist 10mo ago
  _deleted incorrect statement_
  - 10mo ago

technothrasher 10mo ago

I remember cars in the early 2000's doing this. Haven't seen that behavior in years.

bragr 10mo ago

My guess would be: 1. Car entered ferry, loses GPS 2. Car entered dead reconning mode used for tunnels and such 3. Car left ferry, acquired GPS Then either: 4a. Location via dead reconning vasty disagreed with GPS because the car doesn't know about the ferry's movements, triggering some kind of failsafe. Or: 4b. There's just a plain old bug in the condition to switch back to GPS and maybe people haven't noticed because you don't get as badly desynced in a tunnel. >the car must have a pretty good dead reckoning system Yeah all the pieces are there: accelerometers and gyros for stability control, compass for navigation, and the wheel speed sensors give you exact distance traveled.

toast0 10mo ago
My local roro ferry drops you off pretty close to downtown. If you don't get a good fix as you get off the boat before you get into the urban canyon, satnav is pretty hopeless for a few minutes. Doesn't usually take 5 hours to figure out where it is though. At least not on my vehicles, even the one that's always getting confused.
raverbashing 10mo ago
It probably doesn't do dead reckoning even in tunnels And maybe the system sucks to get the GPS almanac if badly desynced
- DonHopkins 10mo ago
  TomTom's have for at least 15 years or so. They have accelerometers to measure the motion when cut off from the GPS satellites. I worked there, knew the guy who developed it, and saw him give a presentation about it.
  - rob74 10mo ago
    That's cool... so I guess this works something along the ways of "calculate the speed via GPS before entering the tunnel, and then try to update this speed using the data from the accelerometer while in the tunnel"? Because as long a the car is moving at constant speed in a straight line, the accelerometer shouldn't register anything...

kbutler 10mo ago

Looks like others have reported similar issues. Entering a navigation route may help? https://teslamotorsclub.com/tmc/threads/map-location-and-routing-after-eurotunnel.335549/page-2?utm_source=chatgpt.com https://teslamotorsclub.com/tmc/threads/map-location-and-rou...

monerozcash 10mo ago
> Entering a navigation route may help? Didn't work for me.

somenameforme 10mo ago

A practical issue is that GPS can be spoofed relatively easily. If autonomous driving became a thing, and ubiquitous, with vehicles that prioritized remote over local consistency, then a single GPS spoof could cause some interesting things to happen. This is probably a concern that does drive decisions, at least to a degree. It creates a weird scenario where you kind of need to trust GPS, but you simultaneously also can't treat it as authoritative. OTOH creating a dumb user experience for a fairly common scenario, to try to preempt a hypothetical scenario is probably not a great idea. A fun problem to think about, though it may be completely unrelated to this issue.

malfist 10mo ago
If it becomes common place, spoofing is easy to counter. Directionality and parallax of the signal is enough to figure out the true signal, all it requires is an additional antenna. This won't prevent jamming, that requires a different mechanism, but spoofing should be prevented.
dlcarrier 10mo ago
I do hope self-driving software works out a better system, before it becomes common place. Autopilot has been incorporating GPS in aviation for decades, and it's still surprisingly common to have major problems when a loss of GPS occurs. The Phenom 300 jet can't fly straight without a valid GPS signal: https://news.ycombinator.com/item?id=12519629 https://news.ycombinator.com/item?id=12519629 Every swept-wing jet has a tendancy to enter a positive feedback loop of rolling and yawing, called a dutch roll, when flying at altitude, so even when not using autopilot, an active system is needed to fly straight and level. If the Phenom 300 doesn't have a valid GPS signal, that system fails.

pjsg 10mo ago

I suspect that my Tesla adjusts its location based on dead reckoning after losing GPS lock except that it assumes that I'm driving forwards. I.e. If I reverse out of my garage, then the map ends up in the wrong place and now I'm driving parallel to the road!

tgsovlerkhgsel 10mo ago

As you're mentioning a RO/RO ferry, recently, and Europe... are you sure you weren't in a GPS-denied environment, where the car (correctly) detected that GPS was jammed or spoofed and ignored it?

monerozcash 10mo ago
It was further west than you typically see significant GPS jamming, and GPS on other devices was fine.

jwr 10mo ago

> On a vaguely related note, driving 3000 kilometers through Europe in an electric car was surprisingly nice. Having done a number of multiple-thousand km trips in Europe in an EV (not a Tesla, nobody buys those anymore) — it's amusing how non-EV muggles think this is somehow an ordeal. It's just fine! There are drawbacks: you do have to use your brain and plan ahead more than you do when burning dinosaurs. But I found that the 20-30 minute stops every 2h really improve how I feel after a day or two of driving. Agreed about prices: there is gouging going on with some crazy margins. When charging at home, an EV is 2-4x less expensive per km than a gasoline-powered car, but when fast-charging on a road trip the cost of energy is nearly the same.

SoftTalker 10mo ago
[flagged]
- namibj 10mo ago
  As a citizen I wish cars had similar driving break requirements as trucks do: mandatory 30 minutes break after 4.5 hours, 9-ish hours per day, minimum 9~11 ish hours break between driving days. Such minimum reasonable rest is what keeps you from killing innocents with your 2-ton weapon/tool.
- jwr 10mo ago
  No need to get agitated. Some people enjoy sitting in the car for multiple hours, some people don't. I found it changed for me as I got older. However, about those 20 minutes — this, again, is a misconception. Stop at a busy rest area or a gas station and actually start your stopwatch. If you are a single male, it might take you shorter. If you are with a family, 20 minutes is pretty much the minimum.
  - DANmode 10mo ago
    Really depends on the air quality inside (and indeed outside) the car.
zamalek 10mo ago

jonathan7977 10mo ago

One hypothesis I can offer is that your car could not, for whatever reason, use assisted gps to download the almanach which relies on mobile networks. Gps devices that download the almanac via gps itself can take up to twelve hours (in higher latitudes i think)!

namibj 10mo ago
It doesn't just become invalid; almanac is good enough to use for satnav for over a day.

kec 10mo ago

Civilian GPS (as in, the DoD’s Navstar) alone isn’t accurate enough to actually place you on a specific road. To compensate, auto navigation systems will snap you to the nearest road parallel to your current heading. Tesla likely didn’t consider the edge case of ferries and other off road situations in their mapping software and you hit some corner case bug.

FireBeyond 10mo ago
This used to be true, but the DoD turned off "selective availability" (the intentional degrading of the civilian signal) back in 2000, and the current generation of satellites do not have the capability (https://www.gps.gov/selective-availability https://www.gps.gov/selective-availability). What they do have though is a separate, encrypted, military broadcast that can be used for those purposes (I think the plan in those situations is to turn off civilian GPS entirely - but I think that there's no reason for that, now, due to the other navigation systems like GLONASS).
- kec 10mo ago
  Even without selective availability gps is only accurate to within about 30’ in normal urban conditions which is more than enough to punt you over to a side street without heuristics on top.
  - everfrustrated 10mo ago
    Your device will use a lot more than the Navstar constellation to get a position these days.

testing22321 10mo ago

My farming GPS does this every time I ship it with my vehicle to a new continent. I always figured it has some code to get a quick location, and it assumes that location is very close to the last time it got a sat lock. I just ignore it for the first day, then it comes good.

pjdesno 10mo ago

Back in the days of MapQuest there was a (usually) very good site called mapsonus.com, but it evidently had one of the ferries that crossed Boston Harbor in its map as a zero distance link. Since it was offline, the bug was obvious although a bit frustrating - you had to put in multiple waypoints to make it forget its urge to send you on the ferry to Hull when you were trying to get to parts of the South Shore.

barnas2 10mo ago

>On a vaguely related note, driving 3000 kilometers through Europe in an electric car was surprisingly nice. I did 2 cross country road trips here in the US (~5000mi/8000km total) and had a similar experience. The nav's automatic charger routing did a great job, and we had 0 issues with charging.