Engineering 44 Combot Peach Project

Combot: Peach JAR

Goal:
The objective of the project was to build a combat robot for an Ant Weight Combot Competition.

Criteria of Success:
1. The combot is able to navigate wirelessly.
2. A transistor-microcontroller circuit controls the flamethrower.
3. It is able to function after the deadly combot competition.

Main Materials:
-LaunchPad MSP430
-Toy Chassis
-Bluetooth Module
-2xVex Motorcontrollers 29
-2xMotors
-2xWheels
-Batteries

Weapon Materials:
-Fly swatter circuit
-Transistor
-Servo
-Gas Tank

Armor Materials:
-Polycarbonate
-Carbon Fiber Sheets
-Piano Wires

How it Works:
A bluetooth module is used to control the launchpad.
The Launchpad sends out different PWM signals to control the speed controller and servo.
The servo releases butane from a container while a transistor would turn on the sparker.

Conceptual prototype designs

First build for competition

The Mechanics:
-Sloped Front at 40°
-Wheel Protection
-Flamethrower weapon
-Center of Mass shifted towards the back to prevent flips

Schematics:
One Problem encountered was that the launchpad only worked at 3-5V while the other devices operated at 6-8V. A voltage divider was used for our initial circuit, but AA batteries were used in the second design.

Every ground is connected to a common ground else it will not work

Bluetooth Module Connected to Launchpad running on Batteries

Fly Swatter circuit connected to transistor and Launchpad

Peach moving via putty

Peach shooting fire via putty

Code to control the launchpad
The code is fairly simple as it replaces the Serial Monitor with a Bluetooth Monitor.
The Servo class controls both the servo and Vex Motor Controllers.
Motors run a range servo write values from 65 - 130.
- Going Backwards = 65 - 87 (fast to slow)
- Neutral = 88-100
- Going Forward = 101 - 130 (slow to fast)

Bill of Materials without Flamethrower:
- Launchpad MSP430 = Free
- Polycarbonate = $10
- Carbon Fiber Sheets = $27
- Bluetooth Module = $20
- Servo = Free
- Toy Body Chassis = Free
Total Cost : $57

Conclusion:
Without a weight limit, it is better to use AA batteries than to voltage divide one LiPo battery to 7 different components while watching for current, and the transistor makes a better switch than a relay.