Overall Design/Frame

First Concept
Version 1: a series of platforms holding the circuitry. Wheels and drivetrain i n the lowest platform, coin mechanism on the top of the robot.

Materials

 * The robot frame will be manufactured used Duron, a hard wooden board. Most robots from previous years use the same material. Apart from that, some acrylic (inside the wheels), velcro and screws are used. To join pieces together permanently, we will use hot glue.
 * Note that a Duron board has a thickness of 0.210 inches. This number is crucial in the design.
 * The laser cutter removes 0.006 inches when cutting, so holes meant to fit the width of a piece of duron are cut to 0.198 inches.

Robot Levels

 * Our robot consists of multiple platforms, or levels. Each level will carry specific circuitry and subsystems accordingly. Based on all the hardware we need, we have a design which calls for 4 distinct levels. Level 1 is closer to the ground and it goes up.
 * Level 1: drivetrain (motors, motor driver, wheels), batteries, line sensors and bumper sensors (just the sensors themselves, not the accompanying circuitry). Most of the weight(motors and batteries) is here; this makes the robot more stable.
 * Level 2: Arduino, PDB (power distribution board), two beacon sensors and accompanying boards. For the competition, we added two additional beacons.
 * Level 3: Circuitry for the line sensors and bumper sensors (one board each), motor and shaft for coin dispenser, H-bridge driving the coin dispenser motor. Besides, we have circuitry to control the two extra beacon sensors of level 2
 * Level 4: Coin dispenser roulette.
 * The levels are interdependent; wires will need to connect them for the robot to work. So, levels 2 and 3 will need to have several holes (Swiss cheese style) to allow the wires to go through.

Heights

 * We are restricted by the rules to a maximum height of 12 inches above the ground. We still need to decide, however, the height of each level.
 * Level 1: the height is decided by how low we attach the motor. The center of the motor shaft will be 3.6cm above the floor (since the wheels have D = 7.2 cm). The height is limited by the size of our caster wheels and by the distance that the line sensors must be above the floor. We decided that the bottom of the car will be 1cm off the floor. So, the motor shaft has to be centered at about 2cm above the bottom plate of the robot (h = 3.6cm - 1cm - 0.22in = 2cm)
 * Level 2: the height here is fixed by the height of the beacons, because this is where beacon sensors are. They have to be 4 inches off the floor, so this will be the height of the top of this level. Then, the columns between the first and second level have to be 7.9 cm tall.
 * Level 3: There is nothing that specifically dictates how high this level should be. Then, for simplicity, we made the columns between levels 1 and 2 exactly the same as the columns between levels 2 and 3. So, they are 7.9 cm tall (3.1 inches). This makes level 3 7.3 inches above the floor.
 * Level 4: The roulette wheel is about 2 inches tall, and its base needs to be at about 10 inches (so we can dispense coins and, at the same time, meet the maximum height requirement). So, again for simplicity, we make the columns between levels 3 and 4 exactly the same as the other columns. They were 3.1 inches tall. Thus, level 4 is 10.4 inches above the ground, which is just enough to dispense coins and which makes us slightly above the 12-inch height requirement (the top of the robot is at about 12.4 inches off the ground, which meets the tolerances).

Width

 * The robot can have a projection on the floor that is, at most, 11x11 inches.
 * The first three levels are based on a square design, 9x9 inches. We rounded off the edges to make it harder to get stuck. But, level 1 has bumpers sticking out, which makes the it larger than 9x9, but still comfortably within the requirements.
 * The fourth level is bigger: it was design to be 10.5x10.5 inches. We want to have the maximum area to be able to collect coins. We also made the roulette displaced (not centered) in the back-front axis. This was done to make it easier to collect and dispense coins in the appropriate places (see Coin Manipulation for more details).
 * The result is that our robot ended up being about 10.5 inches left-to-right, but about 11.4 inches front-to-back. The latter dimension exceeds the requirements by a little bit, which was not a problem.