Primus is the first robot that was built by Team π, which is where it got its name from in conjunction with the pride that the team had with the build. Coming from the word prime which stands for being the first in order and also being first class. The Robot was built with the start of and was built for the FRC game of 2017 Steamworks, but sadly did not participate in the game itself.
There where tree major requirements that highly influents the design of Primus. The requirements are; the robot has to be fully disassemblable, the electro box (a plate or box with the majority of the electronics) has to be able to taken out easily and the robot has to be built with aluminium profiles. The rest of the design came forth out of our strategy for the game itself. We chose for a strategy where we transport fuel (in the form of balls) and gears to the designated goals, which lead to our dissension to give Primus the function of interchangeable modules, one for the fuel and one for the gears.
The mechanical structure of the robot is build up out of 3 parts. At the bottom is the drivetrain which has the function of positioning. This can be seen as the legs of the robot, it gets the whole robot from place to place. On top of the drive train is the torso of primus. The torso has two simple but important functions. first of all, will it protect the electronics inside and secondly it elevates the game-module to a required Height. The game-module is the third part and are actually two modules which both can be used as the third part. The game-modules are used for the goals of the game.
The drivetrain is a basic part of every FRC robot. The drive train has a total of 6 wheels, 3 on each side. The wheels are powered with four CIM-motors, on each side two of the motors are linked to a gearbox. The gear box puts the added torque of both motors on the middle wheel. Subsequently the torque is also transferred to the other two wheels on that side using a cogged belt. The bumper of the robot is attached to the drivetrain. Primus has a special reversible bumper. The bumper has been handmade with fabric letter and can be changed from red to blue in a matter of seconds.
The main function of is the elevation of the game-module. This is important for receiving and depositing game-elements. During the game, game-elements can enter the play field through feeder slots and exit via goals, these are in the form of slots and pegs. The elevation caused by the torso of primus ensures that the game-modules are in the optimal vertical position for receiving and depositing these game-elements. The Torso is mostly build out of aluminium profiles, which were provided to us by our sponsor Newton Automation. The skeleton made out of aluminium profiles consist out of four pillars with an H structure in the middle. This H structure grants more stability to the whole structure, and also functions as and drawer path. The majority of the electronics are mounted on a plate which can slide in this path, this provides easy access to the electronics for reparations. The electro plate can be accessed via the door in the back plate of the torso. The side and front plates are manly for protection. It prevents any objects of coming inside of the torso and possibly damaging the electronics, but the side plates are also being used to prevents objects of coming inside of the torso.
For the fuel module we wanted to make a simple box. The box would have a slanted floor and no top. The balls could be deposited on the front or the back, but would always roll to the front of the robot because of the slanted floor. The idea was simple, but turned out to be too simple and we ran in to a problem. Because of the holes in the balls they wouldn’t always roll down when the front of the box opened to deposited the balls in the goal. This was because the balls weren’t in motion at the moment the box opened and the floor’s angle was not big enough to overcome the tipping point. We also couldn’t increase the floor’s angle because this would conflict with some of the height requirements. We had to find another option, so added a function to the module to vibrate the floor plate and force the balls over there tipping points.
The gear module was designed in the same manner. The gears could be deposited in the robot on the backside and they would slide to the front ending up in a horizontal position. The slide is completely constructed out of one piece of Sheetmetal, after we designed the slide our sponsor Koot Automation provided the fully made slide for us. There was a problem when the gear was in the front of the robot and tilted backwards we couldn’t grab it. That’s why we used a servo to push the gear back into place to pick it out of the robot.