Mechanical Subsystem

Main Components

Our robots consist of five main mechanical components: the wheels, motors, motor mounts, base, and shell.

The Wheels

We decided to 3D print our wheels. They are 3 inches in diameter, and 1/4 inch thick. Because we manufactured them ourselves, they are able to be mounted directly onto the motor. We also made them have interesting geometry. The dragon's wheels had flame decals, and the bee's were made up of hexagons. We didn't make them perfect circles either, which gave them a slight "clunky" driving style. These helped give the robots more personality.

The Motors

We realized that our robots were going to be fairy heavy (an 8-pack of batteries is not as light as we would have hoped). This meant that we would need a drive system with fairly high torque. We looked through the PoE lab's available motors/gearboxes, and found ones that would fit on our robot; our wheels were only 3 or so inches apart so our motor couldn't stick into the robot past 1.5 inches. We then turned them on to see which ones were the highest torque. We decided that having different motors for the two robots would be fun, since we wanted them to have differentiating features. We decided to make the bee faster and the dragon slower. We found that because the app has aslight delay, the slower motors made a much more controllable robot.

The faster set of motors were run at 6V with 250 RPM, and had a gear ratio of 1:48. The bee used the same motors, but they were geared down at 1:90.

The Motor Mounts

Once we had our motors picked out, we needed to make motors mounts to attach them to the rest of our robot. The faster motors came with motor mounts, so we just needed to put holes in the base that could attach to the mounts. The slower motors did not have a motor mount, so we had to CAD one ourselves. We made one with four "posts" that held a corner of the motor in place. The gearbox had a mounting hole through the side, so we put a hole through the post to screw into the gearbox. We then added holes to the base to attach to the mount.

The Base

We made a custom base for each of our robots. These had specific mounting points for the Arduino and battery pack, and holes for wheels and motors. We took exact measurements for the Arduino and battery pack, then added a small offset to account for tolernacing on 3D printers. We countersunk all holes so that we could have screws sit flush, and added pegs to be inserted into the shell for easy assembly and removal.

The Shell

We also made a custom shell for each robot. The shells were made to match features of the animal the robot was based on. The bee's shell was made of hexagons to mimic a honeycomb, and the dragon's had spikes coming off of it. They also had holes for sensors and the IR LEDs to poke through; all sensor holes were placed 1.5 inches above the base for all robots. To attach them to the base, we added holes for the pegs to fit into.


No battle robot is complete without fun decorations! We decided that since we were inspired by two flying creatures, our robots needed wings. We CADed the wings in Solidworks, then added intricate designs in Adobe Illustrator so they could look more realistic.