The first time I tried the line-follower program built into the mBot2 (mBot2_demo 1), it worked perfectly: the bot quickly and accurately followed the track. But when I tried it again the next day, and every time thereafter, the line following has been really wonky; sometimes it seems to be following the edge of the paper more than the track printed on it.
I’ve tried recalibrating the Quad RGB sensor. I’ve tried the Kp line follow program provided under Example Programs in mBlock, but it behaves similarly. Colour detection appears to be accurate: I’ve used a block to report the colour under one of the sensors, and it’s correctly reported as white, black, blue, etc.
The strange part is that I’ve read that the LEDs over the line should turn off, but it’s actually the opposite: only the LEDs over the line are on.
The firmware version is 44.01.011. I shouldn’t have procrastinated on resolving this issue, because tomorrow is the last day to return the mBot2 to Amazon if it’s a hardware problem.