GPS documented P&G?

[bwilson4web]

Hi,

I'm looking for a PnG advocate who has a laptop and would use my GPS mouse to record their driving protocol. All they need to do is record the GPS data in as many PnG runs as they feel comfortable. Ideally, they would also run the same route using cruise control and the GPS mouse, a reference sample. This data would provide engineering units documenting PnG.

I'm seriously confused by the P&G claims. At speeds within the hybrid speed limit, 42 mph for NHW11/NHW20 and 46 mph ZVW30, P&G can save fuel if the speed difference is large enough. For example, my testing with an NHW11:

• PnG 25-43 - 11% fuel savings over equivalent 34 mph
• PnG 15-25 - 14% loss over equivalent 19 mph

In contrast, the Lee and Nelson SAE paper reported a 90% improvement (nearly double!) for an NHW20 compared to the equivalent steady speed. My closest test saved only 11% in an NHW11 versus their NHW20. However, their methodology was based upon using a dynamometer test, not field work.

The problem is worse when trying to get user reports about P&G effectiveness. With one rare exception, I'm not seeing head-to-head comparisons of PnG compared to the equivalent, steady state speed. But this is complicated by the lack of specific, engineering unit based, PnG procedures. Data recorded by a GPS mouse can resolve this ambiguity.

Ebay lists GPS mice for $50-$60. The USB interface one I bought over a year ago reports longitude, latitude and altitude in one second intervals. I've switched to using my Garmin nuvi, coarser data but adequate for the task. So I'm willing to offer my GPS mouse to a PnG advocate to record their Prius driving protocol and share the data with me.

If you are a PnG advocate, please contact me via PM and we'll work out the logistics. I'm interested in the GPS data. Then I can use it to reverse engineer exactly what is being done and see if it works with my ZVW30.

Bob Wilson

[brick]

Bob - What model Nuvi do you use and how do you get it to record? I have a 660 that will do trip totals and averages but I have never tried to data log in this sense. Or do you connect it to a laptop via USB?

I don't really have the right commute for P&G but I always like to have extra tools in the box.

[bwilson4web]

Originally Posted by brick

Bob - What model Nuvi do you use and how do you get it to record? I have a 660 that will do trip totals and averages but I have never tried to data log in this sense. Or do you connect it to a laptop via USB? . . .

I have a Garmin nuvi 260W but the other models should have the same thing. Mine automatically records the "Trip Log," which is saved in an XML formatted file. To access the file:

• plug in USB cable and unit should mount - this makes the nuvi file system available to your computer
• path: /Volumes/GARMIN/Garmin/GPX/Current.gpx - the 'Current.gpx' file is in XML format and holds both way-points and the "Trip Log" data
• analysis - there are XML interpreters however I wrote a Perl program to extract the way-points and "Trip Log" data in a <TAB> delimited form. I'll try to attach it to this message.

Here is an example of the type of data:

$ ./trace /Volumes/GARMIN/Garmin/GPX/Current.gpx
-1 004 34.739017 -86.575697 201.520000
-1 Bob Work 34.726111 -86.664279 -0.110000
-1 Coast 01 34.667243 -86.588927 168.840000
-1 Coast 02 34.662488 -86.597305 167.870000
-1 Coast 03 34.638889 -86.628989 175.080000
-1 Coast 04 34.609462 -86.630221 178.450000
-1 Coast 05 34.601898 -86.630350 177.250000
-1 Coast 06 34.628383 -86.629168 172.920000
-1 Dr Haynes 36.155062 -86.801553 114.040000
-1 Duckworth 34.691953 -86.572217 193.350000
-1 East End 34.623445 -87.081584 -0.110000
-1 Hair Care Lifestyles 34.661346 -86.540009 192.630000
-1 Home 34.652834 -86.571580 184.220000
-1 I-565 W 34.717527 -86.637090 -0.110000
-1 Jet Pep 34.753958 -86.743503 244.300000
-1 Propst 34.738990 -86.575761 202.240000
-1 Saigon 34.680198 -86.747715 189.980000
-1 West End 34.684250 -87.305668 -0.110000
0 2009-08-14 14:16:54 34.658558 -86.569736 227.900000
0 2009-08-14 14:17:02 34.659520 -86.569967 212.500000
0 2009-08-14 14:17:14 34.661192 -86.570519 200.000000
0 2009-08-14 14:17:30 34.663932 -86.571468 190.400000
0 2009-08-14 14:17:39 34.665168 -86.571860 189.000000
0 2009-08-14 14:17:48 34.666130 -86.572172 188.500000

The fields are:

trip counter - I use "-1" for the way points and the rest count up from "0". You get a new trip record with every power cycle and "Reset Trip" from the live mileage and speed display.

GPS date and time - for Central Daylight Time, I subtract 5 hours.

Latitude - in degrees and fraction of a degree

Longitude - in degrees and fraction of a degree

altitude - in meters

summary - the last record of each trip are the longitude and latitude minimums and maximum

Unlike the GPS mouse that reports every second, the nuvi trip data can include gaps, 1 to ~30 seconds. However, even at this relatively coarse resolution, you can load it into a spreadsheet and:

• plot the route
• speed and altitude history
• calculate total kinetic and potential energy

Eventually, I may do some differential GPS measurements. I'll use on GPS mouse to record the GPS at a fixed location and a second one in the vehicle. Then I'll bring the data back and use the fixed GPS data to correct for GPS wander from the mobile unit. But that is a little beyond the pale of what is needed here.

What I'm trying to do is find any PnG advocate who may be willing to help us get engineering units for what they do in the field. Recording GPS mouse data solves the problem.

Bob Wilson