Seeed grove motion sensor control and actuator modules seeed studio 101020009 the grove line finder follower from seeed studio uses an infra red emitter and photo transistor pair to detect the contrast between a black line on a white background and vice versa the line following robot has become a staple project for the robot builder and this sensor is a good place to start you can use one sensor or make an array of them the choice is yours an onboard potentiometer lets you adjust the s