Robotics: Battle Bots

This Instructable will teach you how to make a battle bot using minimal materials, with the body being mainly foam board. The weapon, which spins, is made of Legos and is able to hook onto the other bot, as well as aiding in the avoidance of a pin.

foam board

cutting mat

ruler

Xacto knife

3 continuous servo motors, two smaller ones for the wheels and one larger one for the weapon, but it isn't necessary to have 2 different sizes

2 main wheels

1 smaller wheel

zip-ties

2 popsicle sticks

6 Lego pieces (2 straight pieces and 4 angled pieces)

battery, transmitter, receiver

electrical tape

wire cutters

hot glue

First we came up with an elongated pentagon shaped base that we cut out of foam board. Then we cut a hole in the bottom so that we could easily replace the batteries. Our goals for this robots were for it to be able to corner other robots and for its arms to be able to push aside other robots and corner them. We decided not to make our robot too low down so that it would not flip easily.

We tried to use the least amount of foam board as we could. By doing this, our robot would be lighter weight and would move faster. We chose to cut out the smallest piece of foam core for the base so that we could fit all the pieces that needed to be attached with little wiggle room. We also added a small wheel at the front of the bottom of the bot that would help keep the balance. We also chose a design that would support the wheels on the outside of the bot because that way the front of the bot could be skinnier.

We also chose to not put a full top on the robot. We did that because we wanted to make sure that our rotation weapon could fully operate and wouldn’t accidentally collide with anything that could stop its motion.

The wiring is a very simple process and only requires the battery pack, electrical tape or a soldering iron, transmitter, wire cutters and the motors. For the most part, the wiring is just plugging the motors into the transmitter so they follow the instructions from the remote. The picture shows how to plug in the servo motors. The motors controlling the wheels should be placed in Channel 1 and Channel 2, with the black (or brown) part plugged in on the right side (with the transmitter details on the left side and legible). The weapon's motor should be placed in Channel 3.

To attach the battery to the transmitter solder the red wire of the transmitter to the red wire of the battery and repeat with the black wire. First, use the wire strippers to strip all four of the wires, about an inch. Then twist the exposed parts together: red with red and black with black. Next, solder the exposed wires together. You don't need to completely cover the wires, just be sure that it covers the twisted part. Once the solder cools off, wrap electrical tape over it. This can be seen in the second picture for this step (top left).

Step 5: Electronics placement

When we were placing the electronics we started out by tracing their shapes on the foam board before we cut the base piece. Once we had all of those pieces attached to the base we cut out the exact shape we wanted with a point at the end. We chose a design that fit everything as close as possibly. We also realized that our weapon was too low so we ended up having to mount it on multiple layers of foam board so that it would collide with anything.

Originally, we chose to only mount 2 wheels on the side of the robot but we eventually decided that we should add a small rotating wheel to the tip of the bottom to make it balance better.

The body construction was done over the entire building process as it is dependant on the size of the weapon.

To start, build and attach the motors, transmitter, and wheels to the base (look at the electronic wiring step for how to do this). The battery should be in the back part of the body of the bot, but do not glue it down as you need to be able to change the batteries. From there, we measured and cut the back piece of the bot’s body and attached it. Afterward, we glued and taped the weapon onto the top of the bot.

Weapon creation:

The weapon was two identical lego weapons. To make it, glue a popsicle stick to an angled lego piece, a straight lego piece under it, and another angled lego piece under the straight part. The second angled piece should be set at an angle to get the best results. The resulting weapon should be long, extending out past the bot and have three different levels of lego (see the picture of weapon). The servo motor used for the weapon was the bigger one, with a star part attached on top which allowed it to be more stable. However, another popsicle stick was used to reinforce it. Two zip-ties were used to keep the motor attached to the bottom of the bot (in addition to some glue).

Optional: Use hot glue and a bit of a popsicle stick to ensure that the zip-ties do not slip off.

We did this before doing the other steps in order to ensure the weapon could fully spin around. Afterward, we finished constructing the sides. The bot should be protected from all sides, so on the sides, holes for the wheels are cut out.

This process is very simple: measure the length of the side, cut it out, measure the length of the motor (so the side can fit over the motor), and cut that part out.

From there, we glued it onto the body. To build the front, cut the foam board pieces into long triangles, again trying to cover all the sides. The top of the bot is a bit strange to construct but pretty simple. The hardest part would be to cut a large “V” shape, so it sits on top of the sides but still allows access to the electronics. This required a bit of trial and error. In attaching it to the top, we had to slightly bend it so it would sit evenly on the bot. Here, we used a lot of glue to make sure it didn’t come off while in operation. Finally, attach 2 popsicle sticks across the top of the bot, where the “V” part isn’t on. The goal is to cover the wires and keep the battery in. However, space it out enough that the battery can be taken out (from an angle) and the on/off power switch can still be flipped.

*our bot has popsicle sticks on the bottom as well as we accidentally glued the battery pack to the body, without thinking about needing to replace it.*

To operate the bot, make sure that the battery pack and the controller are on. The wheels will operate using the right side of the controller. The weapon is operated with the left side. In battle, it is easiest to have 2 people driving, one for the direction and one to use the weapon to target specific areas of the opponent's bot. However, you can just have the weapon's control pushed up (or to any direction as it will continuously spin), and focus on driving.