Slug-o-Lete: This Ain't No Bull 2011
Local News Coverage of the event
For this project, we had a little over 4 weeks to construct a fully functioning, dual-mode autonomous
robot from scratch, capable of competing in a simulated bullfight.
In bull-mode, the robot was tasked to find the other robot, the toreador, and “gore” him several times.
Here goring simply means ramming the other robot. In toreador mode, the robot was tasked to find the
other robot, the bull, and somehow place ping-pong balls into a small target container on the top of the
bull. Both robots had to remain within the bounds of the 7.5 foot diameter “bullfighting” ring, demarcated
by black masking tape, or otherwise face disqualification.
Robots could find one another via a small beacon placed on top of each robot. This beacon consisted of
a ring of infrared LEDs pulsing at 2kHz.
Robots were to operate fully autonomously, with no assistance from the engineers once unleashed into the
ring. Furthermore, robots were required to occupy a volume no larger than an 11 inch cube. The
competition would involve two robots operating in one of the two modes for 1 minute; then the robots
would switch modes (i.e. the bull would become the toreador and vice versa) and compete again.
I lead a team of 3 students as we worked from initial concept sketches to our final, integrated machine.
Our team first performed functional decomposition in order to identify the relevant components needed to
satisfy the project requirements:
- Infrared (IR) beacon
- Tape detector
- Ping-pong ball launching techniques
We used the 3D CAD design software SolidWorks to design the robot's chassis and wheels. These
designs, which relied heavily upon tab in slot construction, were then cut out of MDF (medium-density
fibreboard) with a 2D laser cutter (LaserPro Explorer II) and assembled.
We designed a ball launching mechanism using cpu blower fans, PVC piping, and a custom control
circuit. Locomotion was handled through a set of DC motors, custom designed wheels cut out of MDF,
and a few H-bridge circuits.
To hone in on the beacon signal of the other robot, our team designed and implemented custom analog
signal conditioning circuits to process the output of infrared phototransistors. We also used a couple of
Sharp infrared rangefinders to help with distance measurements between the robots. To keep the robot
in bounds, we used six reflective object sensors to discriminate between the black boundary tape and the
white MDF playing field.
A Freescale HCS12 microcontroller acted as the main CPU for our robot, running all our sensor,
actuator, and control software written in the C programming language.
We learned a great deal in this project about project/time management, mechanical/electrical/software
systems, unit- and integration-testing, debugging, and how to get by with little sleep.
CMPE 218/L - Mechatronics
Above images from course document:
|Ping-Pong Ball Launcher/
Cannon Assembly Detail
|3D view of the robot in SolidWorks
|Filter circuit for infrared phototransistors