Default thresholds for ground sensors

[motib]

In the transition from 1.3 to 1.4, the default thresholds for the ground sensors have been changed from 150 and 300 to 350 and 450. When resting on a light-colored table, one sensor on my Thymio returns only about 420, while on a black background or when "in the air", the sensors return values less that 100. These readings are consistent with the old thresholds and I request that they be restored.

[stephanemagnenat]

Your table seems to be not so light at least in the view of the Thymio. In commit 383ca00929fe9e8cb75d1ecd8efd1821ad8b75ea I have updated the thresholds to 400/450, but this will not solve your specific case. But I understand your need, and so I propose to make a "single-click" calibration wizard, that basically collects the ground sensor values while the user is moving the robot over the different surfaces, and then does a clustering and find good points for the thresholds.

[motib]

I would claim that there is a high contrast between the floor and the black tape (see image).

Given the variation in tables/floors and in the sensors, I believe that the provision of calibration is essential.

[stephanemagnenat]

I agree, we will add the calibration as soon as development resources permit (I added it to the Version 1.4 milestone).

[mbonani]

the actual firmware 11 version improve the ground sensor with an automatic gain that makes white value of delta close to 1000. It should help to have the treshold suitable for all robots. Probably it is not more needet.