Autonomous Mobile Robot

Feb 2017

Four Team Members

This is a 4-week team design project for Stanford ME218b, Smart Product Design (Mechatronics) class. The underlying purpose of this project is to give students experience building an electro-mechanical widget. This involves working with sensors, driving actuators, designing event driven software and implementing that software in C on a Tiva LaunchePad microcontroller.

PROJECT DESCRIPTION

The 2017 Stanford 218B competition required building autonomous robots, also known as TaRgeted Extremely Ballistic Universal Containerized Heavy Engineering Trucks (TREBUCHETs). The project’s goal was to apply our course learning in 218, specifically motors and motor drivers, SPI communication, signal conditioning, hierarchical state machines and noise reduction. The theme of this year’s competition was construction, and the robots were required to navigate a field to deliver construction materials (foam balls) to different construction sites (5 gallon buckets).

In the competition, the robots communicated with the Logistic Operations Coordinator (LOC) to determine the requested staging area. The robot were then required to navigate to the staging area marked by a magnetic field and upon arrival, unlock a corresponding construction site by sense the frequency of the magnetic field at the staging area. After unlocking a construction site, as the name TREBUCHETs implies, the robot must shoot the construction materials a minimum distance of 4 feet to reach the construction site. The LOC uses a synchronous serial signaling method to transfer data into and out of the LOC compatible with SPI communications, with the LOC operating as a slave device on an SPI network. A reload station was available on the field to request up to 5 construction material packages (foam balls). The winner was determined by whichever team delivered the most construction materials.

Final Art

Diagram of the playing field

PROJECT SPECIFICATION

The robot must:

Be autonomous and un-tethered.
Use TI's Tiva Launchpad as the microcontroller for the robot
Use the motor's provided to navigate the playing arena.
Use only NiCd batteries. No more than two 7.2V batteries may be used for the drive motors.
Indicate to the audience whether it is team red or team green.
Be fully contained within a 1’ cube at the beginning and end of the game.
May carry a maximum of 5 foam balls
Cost less than $200 to construct
Must be constructed as part of ME218B. It may not be based on a commercial or otherwise pre-existing platform.

JOHN ARRILLAGA CONSTRUCTION BOT

Our strategy was to have a simple design that could move quickly and shoot reliably. Three different shooting mechanisms were prototyped (catapult, flywheel and flicker), before we chose to move forward with a flicker design. We designed the robot to always stay on the black line that intersected all staging areas and the reload station. An array of 6 IR emitter/receivers was used to line follow the black line. For repeatability, robust electrical and software filtering was used for the magnetic field and IR sensing circuits.

Our robot was the winner of the 2017 ME218B Competition.

THE TEAM

Left to right: Matthew Matera, Yiwen Wu, Jason Flahie, Isabelle Heye

Competition video

Mechanical System

Electrical System

Software