DEVLOG 4 - COMMUNICATION

1 full rewrite later, and the robots can form a line again, but better this time! When I started this project I didn’t have a clear vision of how it was going to work. At a certain point, it became very hard to add improvements to the simulation, because it was built on such a shaky foundation. The new version is cleaner and more organised, as well as being more realistic.

Changes

Signals

Instead of solely relying on IR for angle, distance and communication, it’s now split between IR, UWB and WiFi. IR and UWB now only transmit tiny signals for detecting each other. All the heavy communication and networking is done over WiFi.

Communication

I overhauled the flow of communication between the robots. When each robot is turned on, it sends out a message attempting to establish a network. This message contains what other robots it can see, and who goes next. The robots take turns, keeping track of who has already spoken and building the network. By the end, they all have a shared map of who can see who, which they use for formations, and the last robot to speak is designated the temporary leader. I had to make the robots take turns to avoid the signals interfering with each other.

Next I added a controller class to tell the robots when to change formation. When the robots hear this signal, the leader uses the network to find the most optimal line from the current positions. It then broadcasts this signal to the rest of the swarm, and they enter motion.

What’s Next

Right now, the robots never fully settle in a line, they continue to oscillate for a long time. The position estimates (magenta dots) are also quite far off from reality. Right now, the simulation is still ‘perfect’ in the sense that there is no noise or interference. When I start adding noise, these problems are only going to get worse. To combat this, in the next update I plan on implementing more techniques to make the estimates accurate. I also want to add more formations, to test how fast they can alternate, as my goal with this whole project is speed and precision.

Video: Big circles are robots, red dots are IR LEDs, blue dots are IR receivers. Thin green lines are lines of sight, thick lines represent the intended path. Magenta dots are where the highlighted robot believes other robots are located