The 2006 Robot - Joshua

At the beginning of the year, our generous donors Larry and Yvette Gralla had named our new robot after their grandson, Joshua. So it was with this name that our robot carried all the way to the finals using its ingenious features that made Joshua one of our most technically astounding robots.

Engineering

During our early design discussions, it became clear that our robot for the "Aim High" game had to be agile and strong in this new, rough competition. After all, the game consisted of six robots running across the field, vying to capture or herd around up to forty foam balls, and then either pushing them into goals or even launching them. Using photos of other team's drive trains and our own previous robots, we settled on a proven design similar to the one we had used last year in our robot, Yvette: a tank drive with six wheels around which tread would revolve. In order to maintain the high maneuverability this game required, we lowered the center two wheels so that they would act as pivot points, easing Joshua's turning. To ensure that Joshua would not be pushed around on the field, the rubber we chose for the treads had a high coefficient of friction, which was 2.0.

Now, with our drive train decided upon, we had to tackle the other, crucial dilemmas that the game presented. Before we could decide on a specific design, we first had to decide what we were aiming for. After some discussions, we chose to tackle the most ambitious way of scoring on the field, the high goals. Therefore, our design would require three actions to be filled: collecting balls, storing balls, and shooting balls.

In order to collect the balls on the floor, Joshua had to be quite close to the floor in order to reach the balls. Luckily, Joshua was only a mere inch or two above the ground, and so it was sufficient enough to collect balls using horizontally mounted rotating brushes. This system was known as the acquirer.

Next came the problem of storing the balls. To maximize the space available to store these balls, we decided on an untested and ground breaking rotating spiral ramp. This system, which was made of light aluminum sheets, rivets, and a lexan cylinder, was similar to an Archimedes Screw in design. Josuha's spiral reached from the ground all the way up the shooting system, and could store up to twenty eight balls at a time, pushing them upwards using brushes mounted vertically on the center axle. The brushes, however, could be reversed along with the acquirer, allowing balls to be both collected from the ground and rolled out from the acquirer, allowing us to score in the corner goals.

Though scoring in the corner goals would earn us points, our main aim for Joshua was to score in the more ambitious three point high goals. In effect, we needed a way to shoot balls out of the robot. After some deliberation, we decided on a possible solution. By mounting an old pneumatic flywheel at the top of our storage cylinder, we had a way of shooting balls when they reached the top of the cylinder. To give the ball spin on its way out, we compressed the ball using a section of plastic piping. This whole system allowed the poof balls to be launched much farther than was required by the competition.

Finally, we put in place bumpers made to FIRST specifications, which protected the drive train from impacts on the field and cost us almost nothing in weight.

Programming

During autonomous mode, we were aiming for Joshua to be able to score in the high goals. The difficulty of being able to sense the targeting light of the high goals, aim the robot towards the light, and then fire provided a worthy challenge for our more experienced as well as fledgling programmers. However, even our best programmers needed help, and they found that help in the form of Kevin Watson, a supervisor in NASA's Jet Propulsion Lab who also wrote algorithms for the identification and positioning of a light source within a given field for all the FRC teams around the world. This, along with our own code and the camera that was given to all the teams, allowed us to write code that would accomplish these highly complex tasks within the ten second time frame in which we were alloted.

However, during competition, a major failure in one of our treads jeopardized our entire robot. Though the engineers ordered and installed omni wheels for Joshua, the code that was originally used to shoot balls at the high goals could no longer be used due to these changes. Thankfully, our programmers compensated magnificently and managed to write code that still allowed us to score in the corner goals during autonomous mode.