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ME 218B Winter Quarter Robot

Robbie O'Doyle, Side View

Team ODST - Robbie O'Doyle

Robbie O’Doyle, half a play-on of robot and half allowing us to shout “O’Doyle Rules!” during the competition was built for Stanford’s Smart Product Design course, ME 218 B. A course based on teaching how to build and program embedded systems.

Top View, Hands for Scale

Top View

About 3 weeks prior our class was split into groups of 3 and given the assignment of building a robot to play a simple game. Autonomously drive on a small 8ftx8ft table top court and knock down small targets as they were assigned wirelessly.

We were given 2 Maxon motors, an E128 microcontroller, a few bags of Nerf balls, and a max spending of $150.

The robots varied widely, but for ours:

Navigation was done by following a small strip of black tape in the center of the court using light sensors. Location and direction was determined with the wheel motor’s encoders (incredibly precise devices that relay how much each wheel motor has rotated).

Shooting was done using a small wheel and motor (like a baseball pitching machine) and a servo motor for loading.

Gun Wheel and Ball Loading Track

Gun Wheel (Below Square Barrel) and Ball Loading Track (with many balls...)

CAD Model and Construction

The full robot assembly can be split into 3 “tiers” made almost entirely out of masonite, shown in dark brown (which is kind of like plywood, but worse…).

Robot Assembly All Tiers

All of the hardware used for shooting is mounted to the top tier, which includes the gun wheel (in blue) and the Nerf ball reserve slide/ramp thing (in white and blue). At the end of the ramp is the loading mechanism, which is kind of hard to see at the moment. It raises the ball from the ramp to the back part of the gun barrel (the square tube).

Robot Assembly, Tier 3 RemovedWith the top layer removed you can see the 2nd, more boring, electronics board tier. Each green square is a board we soldered, the far left one is for our tape sensors, the two middle ones are for sensing an infrared beacon and for connecting the big green computer board (Motorola E128 microcontroller) to everything.

Robot Assembly, Tiers 2 and 3 RemovedThe second tier removed you can see the batteries (light brown, 7V each) and the green “power distribution” board (which makes 14V and 5V from the two batteries to be used in other parts of Robbie.

Robot Assembly, Tiers 1.5, 2 and 3 RemovedRemoving the batteries and it’s supporting board you can see the drivetrain. The black cylinders are 2 Maxon (awesome) motors with encoders attached to the back (which we can use to get accurate info on motor rotation and speed). The two orange wheels are rollerblade wheels which have been modified to be attached to a shaft. Belts and pulleys connect the two in such a way that 1 motor rotation means 8 wheel rotations.