The images below show the position of our tape sensors and the circuit used for tape sensing. We had four tape sensors in total with the center two used for going in a straight line and the side two used for detecting turns. As soon as any of the two center tape sensors no longer detected the black line, the bot would turn in order to align itself along the black tape. This was achieved through proportional control feedback, meaning that how fast the bot turned to find the line was proportional to the difference between the readings of the center two tape sensors. A higher difference meant a sharper turn and smaller difference meant a smaller adjustment. Finally, the two side sensors were used to detect junctions in the tape where the bot needed to turn and move along a new tape line. When any of these two sensors detected black tape, the bot would determine which way to turn based on the sensor triggered and proceed to turn. Note that if both sensors were triggered, the bot was coded to turn left.
As discussed in our Strategy Section, we ultimately used tape following in order to move across the front tape line demarcating the force bins. This only required our bot to be able to stay on a line of tape, a relatively simple task. However, our tape following was much more complex and incorporated added functionality we never used. For instance, when we reached the end of this front tape line, our bot was able to realize this, turn around, and follow the tape line back from where it came. Furthermore, our bot was able to follow the tape line from the FLAP zone to this front line, navigating three turns along the way. Although we never utilized this functionality, we just figured following the tape was the most reliable and easiest way to get our bot to the force bins, and therefore we designed a very robust tape following system. Also note that we had originally planned to immediately move to the FLAP zones and then line follow to the force bins, a strategy that would required this added tape following functionality.
Screenshots of the tape sensor CAD assembly can be seen below. Also, the code used to implement our tape following can be found attached below.
tapesensing.ino | |
File Size: | 2 kb |
File Type: | ino |