Robockey is an annual tournament at the University of Pennsylvania. It serves as a capstone project to MEAM 510: Design of Mechatronic Systems. In 2014, 24 teams made of 89 mechatronics students competed. Each team designs, fabricates, and programs three autonomous robots that compete against each other in a game of robotic hockey.
Above the rink, a "constellation" of infrared LEDs serve as a navigation tool for the robots. Using unique infrared cameras salvaged from Wii Remotes, each robot then utilizes coordinate transformations to determine their relative location to the rink's origin. The electronic puck also emits infrared light radially, and is tracked by the robots using infrared phototransistors. These phototransistors and other various sensors feed information to the MAEVARM M2 microcontroller which determines the robot's actions. Additional phototransistors are used to sense if a bot as possession of the puck. If one of the attacking robots gains possession, it is capable of rapidly plotting and traversing a path to the opponents goal. At the "two-point line", the strikers are also capable of shooting the puck for double points if the 18V push solenoid is charged and ready to fire. The high voltage of the solenoid booster circuit and brushed DC motors are carefully separated from the logic circuits on-board. Our team utilized a unique stacked perfboard design so that each independent perfboard could be connected via a series of headers along each board. This allows for signals and power to be passed along each board, and allows all pins of the microcontroller to be accessed from any layer of circuitry. Limit switches placed along the back of the goalie and sides of the strikers allow for verification of the wall location when executing certain commands.
Each robot has large brushed DC motors that attach to the wheels via aluminum spur gears. These gears were implemented in order to adhere to the strict size restrictions of the competition by mounting the motors off-center. To gain more traction as well as a head-to-head advantage, each of the robots was loaded with lead shot. This allowed for an average team weight of approximately 7 lbs and ultimately proved to be a huge asset in the tournament.
The basic programming of the strikers allowed for the ability to locate, control, and score with the puck. However, our team also implemented inter-robot communications in order to add an additional level of strategy. Whenever a robot gains possession of the puck, the behavior of the other robots is slightly altered. For example, when one striker gains possession and moves to score, the other striker acts as a "midfielder" by shadowing the first robot in the case of a rebound or loose puck. Most importantly, this prevents the robots from contesting the puck simultaneously, which results poor puck control and potential damage.