viewtopic.php?f=9&t=2243
In this thread I'll recap how things worked out in the 2014 Silver State Classic Challenge. For those not familiar with a road rally, it is a timed point to point race on a closed public road. A car wins by finishing closest to their target time.
HLT was not designed for road rally use, but with a little work (well, a lot) and the patient support of Harry, it is possible to use the app and be competitive. Basically, what we do is create a reference lap in a spreadsheet and load into HLT that we can then use to pace us through the actual event. The thread mentioned above describes the details.
So, how did it go?
We (myself and my navigator) used HLT on an iPhone 4s and Gen 3 iPad. We ran it on two devices for redundancy and so we could compare the results at the end of the race. Both devices were linked to an XGPS160. The iPhone was also linked to a GoPoint BT1.
Our start time was 1:11:00.00 and target finish time was 2:00:05.45 (49:05.45 elapsed time and the same as our programmed reference lap).
HLT was programmed with a standing go start. When our start time arrived, we started briskly and HLT on both devices started as planned.
About 10 minutes into the race, the iPad froze in what appeared to be a GPS issue. HLT was closed and restarted, but it froze on the start screen when restarted locking up the iPad. Rebooted the iPad and restarted HLT, but by then it could not get back on "course." The iPad was done for the day.
Meanwhile the iPhone continued to work, but the gap calculated against the reference lap got much larger (10-20 seconds) than I believed it should be. Then while the gap was displaying -25 it suddenly changed to -3 (more in line with expectations). This occurred at about 1/3 of the way into the race in an area where the distance between the points in my reference lap are quite large (but these types of large gaps were common throughout the reference lap). For the last 2/3 of the race, the gap calculation seemed very reliable.
Shortly after the above behavior, the iPhone locked up. Assuming another GPS issue, we switched off the XGPS160 and the iPhone recovered using it's internal GPS -- thank goodness.
The last few miles we got the gap down to -0.3 - 0.0. The value of the gap jumped back and forth within that range. I don't think there is any way I could have kept it steadier, so that was the best I could do.
Default sensor delay settings were used.
Here are the numbers displayed or recorded by HLT:
1. Gap at finish: near 0.0 (from timer view)
2. Difference displayed in large font moments after finish: -1.01
3. Lap time displayed in Lap List: 49:04.44
All the following are from the .hlptrl file (UTC times converted to PDT)
4. Start time: 1:10:59.93
5. Finish time: 2:00:05.17
The fact that we had to switch from the XGPS160 to internal GPS part way through may have caused some issues as their sensor delays differ by 0.8s. The issues I'm referring to are: why is #1 so different than #2? Also, the difference between #4 and #5 is not quite the same as #3?
Our actual results were -0.9554s, or finishing at 2:00:04.43. So the difference was very close to #2. Finishing time was 0.73s sooner than #5, but again this may be due to the different sensor delays.
We finished in ninth place out of 28 in our class.
With all that happened, I am delighted with the result. I realize HLT is not designed for this and that I am trying to attain a level of accuracy in a system with many moving parts that may be unrealistic. But it is the tool (i.e. app) that I know how to use, and by golly I'm going to use it
We had a blast and that is what counts!I would like to get to the bottom of the XGPS160 freeze ups. All my testing beforehand with the XGPS160 went fine, so the problems during the race were a surprise.
Thanks again to Harry for his support!
Deven
