Charging locations grid based and related problems.

[WattsUp]

When you think about it, it does make some sense...a lot of cars don't have a Nav system, and therefore may not have a GPS receiver.

I doubt, even under ideal conditions, the use of a cell triangulation would make for a reliable navigation system. Navigation would only work where, 1) there were enough cell towers and, 2) the towers consistently had the required capabilities (directional antennas, etc.). Both conditions are probably frequently not met, and certainly navigation would simply stop working in many areas.

Even when everything comes together, cell triangulation could still be as much as 200 meters off. Civilian GPS is accurate to around 3 meters.

 

[michael]

This discussion isn't about navigation. It's about locating the vehicle for charging purposes. Navigation and location have different requirements.

It wasn't my idea that the charging location system should use cell triangulation rather than GPS, in fact the idea surprised me as I said several posts above. The point is that Ford SAYS it uses cellular and based on what I now know, it seems plausible.

In fact, since we all agree that there IS a problem with non-repeatable charging location estimation, and since as you point out GPS is accurate to a few meters, this tends to support the idea that they use the imprecise method for one reason or another.

While our FFEs all include nav, many other plug-in cars do not. Nav is not standard on Fords plug-in hybrids, for example.

 

[michael]

So cell phone triangulation give location to 50-200 meters, typically....this is consistent with the type of mis-location we are dealing with here. So the guy at Ford may have been telling me correctly.

Possibly, but I think there is an important difference to point out...

The "mis-alignment" of charging locations manifests as an exact and repeatable grid alignment, wherein the charging locations recorded by MFM always vary from the actual charging location as the result of an apparent alignment to a fixed grid. This suggests to me that the mislocations are the result of deliberate quantization (rounding) of the otherwise accurate GPS coordinates, as opposed to "random error" that could be attributable to cell signal triangulation (though I still highly doubt triangulation is even being used).

In my case, when I've removed previously-recorded charging locations and waited for them to re-appear (after charging there again), they always re-appear in exactly the same grid-aligned locations. As a test, I also observed that the alignment behavior persists across an account reset. Such behavior does not appear to me to be due to randomness -- it appears to be deterministic, and therefore is very likely to be intentional and algorithmic, IMO.

I believe the MFM server-side software is specifically doing this. It is not just happening due to error.

Yes, of course. We have discussed that at length. The point is that imprecise location estimation increases the risk that the software will align to an adjacent grid. If it were accurate to a few meters, then only in the few cases that one was very close to the boundary would this occur.

Since the problem occurs so often, this tends to suggest the Ford guy was right, that it uses imprecise cellular location rather than precise GPS.

The greater the randomness, the greater the chance it will pick the wrong grid. In fact as I think back, I have seen my car placed not at the adjacent grid, but at the next one beyond.. If they were using GPS, this would be very, very unlikely.

And, as he acknowledged, as ATT continues to abandon 2G, this problem will become worse.

 

[hybridbear]

While our FFEs all include nav, many other plug-in cars do not. Nav is not standard on Fords plug-in hybrids, for example.

While not all the Ford Fusion Energis have nav on the dash, they all have the same GPS system that the Focus Electric has. Having navigation on the dash is a software option, not a hardware change. The same is true of the Fusion Hybrid. Our first Fusion Hybrid (before we had the Energi) didn't even have MFT and it still had the GPS hardware which is used for EV+ mode.

 

[michael]

While our FFEs all include nav, many other plug-in cars do not. Nav is not standard on Fords plug-in hybrids, for example.

While not all the Ford Fusion Energis have nav on the dash, they all have the same GPS system that the Focus Electric has. Having navigation on the dash is a software option, not a hardware change. The same is true of the Fusion Hybrid. Our first Fusion Hybrid (before we had the Energi) didn't even have MFT and it still had the GPS hardware which is used for EV+ mode.

Then it is an even stranger that Ford would have chosen to use cellular location services, assuming that they actually did....