Implementing Leader-Follower Algorithm

_


While trying to implement the Leader-Follower algorithm on the NXTs using C language many different obstacles got in the way. The first challenge I faced was to get one robot to follow the other one. The robots have no since on direction and have limited memory to keep track of where the leading robot is. One of the first things that I thought about was to add a pink ball to the leading robot and have the follower have a light sensor which can locate the pink ball and follow it. Such idea proved to be inconvenient based on the fact that the light sensor get less effective as the distance increases and a the chances of losing the leader robot get higher, also the ball can fall off the robot. Adding an LED light to the robot makes it easier to find instead of having a ball. But this means that the leading robot has to be moving slower due to the fact that the follower robot has to make a 360 degree turns every time it needs to find the leader.

Another approach is to use a HiTechnic Compass Sensor which measures Earth’s magnetic field in order to provide accurate navigation. Also, it can be used to calculate the current position. This can be used by the robots to send their positions through Bluetooth or IR to help achieve the Leader- Follower algorithm. A Codatex RFID Sensor was under consideration, it’s a sensor that can read up to five-byte transponder numbers into the NXT Brick. It can be used to send directions to the follower robot but its range is very limited 30mm which defeats the goal of using it.

Another interesting idea was to use a Vision Subsystem v2 for NXT (NXTCam-v2) - This vision subsystem connects to NXT on a standard sensor port, and tracks up to 8 colored objects. It reports coordinates of each object to NXT. Vision is very complicated in the robotics world, but I believe such a sensor would help greatly in achieving our goal using the Leader-Follower algorithm. One of the disadvantages that it costs about $150.00, which I don’t know if it fits with our budget or not.


Time: 8.5 hrs.