VBOX Sport And HLT different data

Discussion related to external and internal GPS / GLONASS / Galileo / BeiDou sensors
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VBOX Sport And HLT different data

Post by teo_parvu » Sun Jun 03, 2018 12:56 pm


I've used VBOX sport for the first time with HLT and It seems that I get different G-force data. I've choosen VBOX Sport from the sensor list and recorded my lap with HLT. Later I've seen that the data from HLT differs from the one from VBOX's SDcard. Speeds, timing is exacly the same, but different lateral acceleration.
On the vbo file I get close from @1.5 - 1.6G:


On the HLT overlay-ed video just 1.2-1.3 on full slicks:


Could you help me understand? Which information is valid? Maybe how can I use the data from VBOX Sport?
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Re: VBOX Sport And HLT different data

Post by Harry » Sun Jun 03, 2018 3:52 pm

LapTimer *measures* acceleration using the smartphone's accelerometer. Due to smoothing (for noise reduction), this measurement tends to come in slightly too low. Although RL offers devices measuring acceleration, they have a legacy of calculating acceleration from GPS. So if you open a VBO file in Circuit Tools, you will see calculated acceleration. I cannot comment on the absolute accuracy that can be achieved using this approach. 1.5 to 1.6G is quite high...

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Re: VBOX Sport And HLT different data

Post by gplracerx » Sun Jun 03, 2018 11:25 pm

You can minimize accelerometer smoothing in HLT by increasing the accelerometer data rate to 100Hz from the default 30Hz in Expert Settings. This is a requirement, in my opinion, for autocross data logging.
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