A procedure for setting accessories' delays

Discussions on all kinds of sensors (GPS, OBD, video/audio) and other accessories like mounts
Mateusz
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A procedure for setting accessories' delays

Postby Mateusz » Mon Nov 13, 2017 3:53 pm

Is there a "scientific" procedure of setting proper delays for accessories (OBD and internal GPS in my case?)? Assuming consistent OBD update rate and the fact that Harry probably tested the default internal GPS delay (1.5s) extensively, I see two options:

1. Analyse a lap or a performance run and broadly align peaks of OBD with GPS speed reading
2. Video record a lap and a dashboard during acceleration and try to align speed somehow (that requires proper calibration of the dashboard speedo, which is always off compared to both GPS and OBD reading). Using standing start might be easier?

Does it make sense?


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Harry
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Re: A procedure for setting accessories' delays

Postby Harry » Mon Nov 13, 2017 4:04 pm

Yes, if the standard setting is not good enough, I'd recommend a GPS / OBD alignment using speed and wheel speed first. Please keep in mind that GPS speed may be over-smoothed and allow it to be a little late because of this. In addition, compare longitudinal latitude changes from minus to plus (or vice versa) with the position speed is increasing after decreasing (or vice versa). This should align the acceleration, GPS and OBD sensors. Now, do a new recording to have an aligned set of data. To derive the data / video sync, it is usually best to compare audio and acceleration / rpm. This is what we humans see first.

- Harry


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