Swarm Robotics Week 3: All About the Algorithm

Hey! I’m back to report about my third week of my Senior Experience project. My primary objective for this week was to implement a positioning algorithm for my swarm drones.

Let me back up and explain what those big words I just used meant.

The drones in my robot swarm are very simple. They can do two things: drive (forwards, backwards, and right/left steering) and connect to the Internet. The drones have no on-board sensors, so there is no way for them to know where they are. They cannot sense if they are about to bump into each other or even detect if they are about to drive off a table. If you have been keeping up with my blog, you’ll know that I have also been building an Internet-connected camera that can track the locations of the swarm drones based on their colored hats. Last week, I planned a system for the camera to send the location of the swarm drones to the drones themselves. The last step is to program the drones to be able to to use the location data from the camera module to navigate around a space and drive to a target

I started by assembling the camera module. The module consists of a Feather Huzzah WiFi board and the PixyCam camera that tracks the robots. I built a 3D printed case for these components that then attaches to a tripod to hold it above the table that the drones will live on.

Next, I had to write some code to make the camera module output the location data of the swarm drones in a way that the drones can then understand. Here is how the code works:

1. The WiFi board in the camera module asks the PixyCam for the coordinates of every drone that it sees as well as their color

2. The WiFi board hosts a webserver where it displays a string that has the color of the drones it sees and their XY coordinates

3. Every time a drone requests data from the webserver, the module will recheck what the camera sees and will update locations

So, to recap, the camera module tracks the location of each drone, and then each drone connects to the webserver to find its location. Here’s the tricky part: now that the drones know their current location, how can they navigate to another location. This is where the position algorithm comes into play. The algorithm works as follows:

1. The drone reads its current location from the webserver

2. The drone drives with both wheels turning at the same speed for a short time interval

3. The drone reads its location again

4. The drone compares the two locations and determines how far it has moved and in what direction

5. The drone compares its current location its target location and determines the distance and direction to this point

6. It compares the two vectors and finds the angle between them

7. If the objective vector is to the right of position vector, the robot speeds up its left wheel, and vice versa

8. Repeat until the robot approximately reaches the target

Here is a picture to aid my explanation:

Swarm Robotics Week 2: The Swarm Invades the Internet

As week two of my Senior Experience project draws to a close, I am back with another update. Last week, I planned, designed, and built a swarm drone. Over the last few days, I programmed this robot to move and communicate with the Internet!

Some of the code I wrote to control the robot drone

As I wrote about last week, I have put significant effort into making my swarm robots as simple as possible. One benefit of this simplicity is that it makes it easier for me to program them! The “brain” of the drone robot is an ESP8266, which is essentially a tiny, WiFi-enabled computer. Unlike other WiFi chips though, the ESP8266 makes programming wireless communication extremely simple. Espressif, the manufacturer, also has lots of documentation on how to use the chip with other peripheral devices, such as, in my robot’s example, servo motors. As a result of all this, I was able to very quickly write code to make my robot move.

My code needed a bit of tweaking and iteration, but, as you can see from the video, the robot is speeding around and looks great!

Now that I have a moving robot, I need to build the infrastructure for other swarm drones to function and work collaboratively. Things can get very messy when devising wireless systems, so it is important to be very organized. I created this diagram to convey how the Camera Module will communicate with the robot swarm. This will be very handy once I start programming the different devices to communicate.

While I have decided to use WiFi to coordinate communication for my swarm, I still have many options for data-exchange methods within WiFi itself. From UDP to IoT packages, there are dozens of different WiFi-based protocols to choose from. After conducting research and experiments on a number of these protocols, I decided that using a “webserver” would be the best option for my project. A webserver may sound fancy, but all it is is just a website that can change dynamically to both take in and put out data. Next week, I will dive into programming the webserver that will serve as the backbone of my robot swarm.

In the meantime, I have started to design a 3D-printed enclosure for the Camera Module that will track the motion of the robot swarm. Here’s a sneak peak!

Swarm Robotics Week 1: Hats, Limes, and Wheelies

Hey! I’m back with my first Senior Experience project update! This past week I hit the ground running on the first steps of building my swarm robots.

The first order of business was the build the drones: the individual robots of my swarm, the “worker bees”. I began by looking for inspiration from existing swarm robots. Although I’m going to be an engineering major next year, at heart, I’m an artist. I’m always thinking about how the things I build make people feel and how design elements evoke emotion. Swarm Robotics is a complicated topic, but I hope to convey it to people more easily by incorporating visual language into the design of my swarm. The basis of swarm robots is that each individual robot is extremely simple, so I was inspired to design each of my robots as one of the simplest forms in existence: the cube.

But before I could even get to prototyping the robot’s body, I had to gather my components. Since I only need my robot to be able to move in an XY-plane and communicate wirelessly, I only needed four electrical components:

• WiFi Microcontroller

• 2x Continuous rotation servo motors

• Small rechargeable battery

The only other parts I needed were two wheels to let the robot drive itself around!

Once I got all my parts, I went on to designing the robot. I settled on a two-piece design for the drone: one body piece and one “hat”. The body houses all the components I just listed and uses magnets to slot into the hat. The hat is a merely a cover for the robot. Each drone in the swarm will need to be a different color (for reasons we will talk about later), so having the hats as an interchangeable part will make producing these drones easier.

While this all may sound simple on paper, it actually took quite a while to design this. I used a program called Fusion 360 to make 3D schematics for the drone, and then used a 3D printer to turn the schematics into real parts. Even then though, the parts did not fit perfectly, and I had to iterate many versions of the design.

All 10 prototypes of the robot’s body

While I was waiting for my robot parts to be 3D printed, I began experimenting with the PixyCam. Most cameras, like the one on your phone, only sees individual pixels of color. The PixyCam on the other hand, can actually understand what it is seeing. This is a hard thing to describe with words, so here’s a video of me using the PixyCam to recognize limes:

Eventually, I am going to use the PixyCam as a sensor for every drone in the robot swarm. It will track the location of the robots so that the swarm knows where its moving.

While I write this, I am finishing up the final version of the drone. Next week, I am going to make the drone to move, get it connected to the Internet, and make it talk to the PixyCam.

Senior Experience Project: Robot Swarms!

Throughout High School, I’ve built all sorts of robots, from robots made of PVC pipes to ones made of rubber, and robots powered by electricity as well as ones powered by air. The field of robotics is incredibly interesting to me and has driven me to experiment and research a variety of robotic concepts over the past six years.

One area of the subject that I have always dreamed of exploring is swarm robotics. This discipline is, at its core, based on nature. Bees, ants, humans, and many other animals use social organization and collaboration to complete tasks more effectively than they could alone. This behavior is increasingly being adapted for networks of many small, identical robots.

Giant termite mound

Mound-building termites are a great example of swarm behavior. Each individual worker termite is small, blind, relatively weak, and identical with very limited intelligence. Despite being so meager on their own, a swarm of termites is capable of building massively tall mounds, with intricate tunnels and thousands of chambers and rooms, all from dirt. A great feat achieved by many, small drones working together.

For my Senior Experience project, I want to capstone my work as a High School roboticist by exploring swarm robotics. I plan to lay the groundwork and build a platform for the development of robotic swarms. My final product will consist of a group of small, simple robots only capable of movement and wireless communication. I plan to coordinate every drone in the swarm over WiFi. Each drone will be able to communicate with the others and work towards a common goal.

Over the next five weeks, I will post weekly updates on this blog to show my progress, my failure, and my learning throughout this project. Stay tuned!