Border detect and line follower not working

hi i’m trying to get my robot to follow a line but ii cant seem to get it to work.
i have two old type robot zumos one with a li ion modification. the one with the mod both the motors work and Im receiving data from the qrt sensors but in the serial monitor nothing seems to react to anything. the other the motors don’t move.

any help would be appreciated!


I think we should focus on troubleshooting one Zumo robot at a time. Can you provide more details on the Zumo without the LiPo modification (e.g. LED behavior)? Are you able to get any of the other examples to work on that Zumo? If possible, can you post a video showing the Zumo’s behavior?

- Amanda

unfortunately I think i have run both zumos off lipo battery voltage also all three qtr sensors that i have.So when powering on I get the qtr sensor array lite up red and the 4 red and blue leds on the zumo lite up also the arduino is lite up red. the uv leds are lite up purple (using a camera).
the example code showing the qtr sensor output is below. the first is covered and the second is uncovered (using a bit of paper).


Those values look pretty low, however, it is difficult for me to help you troubleshoot the problem without knowing more about your setup and how you are testing your modified Zumo(s) (e.g. which example sketch did you use?). Please answer my previous questions and post close-up pictures of your Zumo(s) showing the board, the LiPo modification, and the Zumo reflectance sensor array.

- Amanda

i’ve soldered the battery terminals directly to the positive and negative terminals where the aa battery used to be. i used the qtr raw values sketch.

Can you post a video showing how the values in the serial monitor change when you slowly pass the sensor over your line (using the qtr raw values example)? How many cells is your LiPo battery?

- Amanda

i cant post a video my phone is broken. all that shows is a bunch of values that don’t change when i put my hand over it. its not the arduino as i just tested a new one.


Ideally a video would show us how you are moving the sensors/zumo and how far from the line you are holding them, what the line you are testing with looks like, and if there are other environmental factors that might have an effect, but we would just not think to ask about.

If you are not able to post a video though, please post pictures that show the solder joints on the sensor array and front expansion area as well as how the sensor is connected to the Zumo. Could you measure the voltage of your LiPo battery? Just putting your hand over the sensor is not a great test. Could you try moving the Zumo over a black line on a white board or white paper while you run the qtr raw values example? Please post pictures of that too.