Autocross with more than one lap

Any discussion on using LapTimer. Please use this forum in case you need guidance on how to use LapTimer or perform a certain operation
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cayman pyrat
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Autocross with more than one lap

Post by cayman pyrat »

I tried to use HLT today at our autocross which was setup as a two lap circuit. Did the normal AX setup and start and finish, including the trigger directions. However, when I drove the first laps, the finish trigger was early as I passed nearby the finish line (there is a split about 3-4 meters before the finish line with a 45 degree turn to the left to go around the course one more time). How can I setup HLT to avoid an early trigger of the finish line?
AX Jun 21 final.jpg
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Harry
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Re: Autocross with more than one lap

Post by Harry »

This is not easy to set up reliantly. Using the internal GPS, there will not be enough data to detect passing s/f after lap 1. With a precise GPS, you can try setting the detection corridor for the finish to „Normal“. Every POI can have an individual corridor. Remove the split in case it is near finish. After every trigger, LapTimer will pause detection for a few seconds. So in case triggers are too near to each other, the following trigger may be ignored.

To be sure you get data recorded, I‘d change the finish trigger to a stop / start trigger. This has two effects: in case it is detected after lap #1, you will get separate times for lap 1 and 2. These can be merged after the fact or simply added up. But you will always get another recording when passing finish. It needs to be canceled once you have reached the parking area.

Harry
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cayman pyrat
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Re: Autocross with more than one lap

Post by cayman pyrat »

Got it to work!

I first used another tip on the forum to reset the Dual XGPS to 5Hz (Use the Dual GPS SkyPro app to reset XGPS150 to 5Hz, shut down, launch Harry's, connect to XGPS150, verify 5Hz setting retained). This provided the necessary fine position to avoid the finish trigger.

Next, when setting up the autocross, I set the trigger direction to about 15-20 degrees right of centerline -- this allowed for trigger sensing without being tripped by the turn to the left on the lap.

Finally, after the two steps above did not work, I went into expert settings and modified the following:
Allow Low Speed trigger -- checked
POI detection -- set to Narrow
Deviation trigger -- set to 45 degrees
Narrow corridor -- set to 7.0
Narrow sector -- set to 15.0
Normal corridor and sector -- both set to 15.0 (unchanged?)
Wide corridor -- set to 10.0 (this may be a setting from a track day problem at UMC)
Wide sector -- set to 18.0

With all the above settings in place, I drove a slow full two lap route, and the attached full track was setup!

Comment welcome on whether or not the expert settings tweaks really helped or whether the offset finish line trigger direction was the key.
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Harry
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Re: Autocross with more than one lap

Post by Harry »

The corridor type selection (Narrow / Normal / Wide) is as follows (top to bottom priority):

- for POIs with a defined corridor type, this type is used
- for POIs with a defined direction the Wide type is used
- for all other POIs, the type defined in Expert Settings is used

With the general recommendation to always set a driving direction, the last case is never used and the Expert Setting has no effect.

Harald
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