3RC Sensor Array Troubleshooting

I am attempting to make an autonomous robot that can follow a line using an Arduino. It was working fine until one morning, I kept getting wrong readings when the robot would move to the left side of the line. Instead of the readLine() function printing out 0, it was printing out 2000 and I could never get a reading under 900 for the left side of the line. This continues to happen each time I calibrate it. I am using an external power supply to run the motors of the robot and the Arduino is powering the sensor. Could the sensor be damaged or is there another problem with it?


I am sorry you are having problems with your 3RC-Sensor Array. From your description of the problem it seems possible that one of the sensors is damaged, but from the pictures you sent in your email to us, I see some other things that could be causing problems in your system too. The wires connecting to the Adafruit shield used on the robot in the pictures do not appear to be soldered, and there are some other solder connections that look like they might be cold solder joints. Also, the sensor array seems too high to detect the line. The optimal sensing distance for this sensor is 0.125" (3 mm).

I suggest addressing those issues and simplifying your setup to test the sensor. Can you try connecting directly to the Arduino and run the “QTRRCRawValuesExample”?


I connected the sensor directly to the Arduino and this is what I got.

Directly over the line: 2500 1844 2500
Right of the line: 1640 1152 2320
Left of the Line: 1636 1148 2220

Did you change your setup based on the issues I pointed out in my last post? The “Right of the line” and “Left of the Line” readings seem very similar. Can you post some pictures that show your line follower track and how the robot is placed on it for each of the three readings you took? Also, can you post some pictures of the sensor side of the 3RC Sensor Array and the wiring going to the Arduino (please be sure to show all of the wires in one picture so I can trace them).