@WoW_Remotion: I took a speed sensor and wrapped the output through a couple of empty microchips with circuit nodes. This introduces a few frames of lag to the signal. Then I used a direction combiner to compare the original signal to the delayed signal, this detects whether there has been a sudden decrease in speed (crash). I uploaded a pic of the circuit, check my recent photos. Contact me if it's still not clear (I might not have explained it very well).
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