Calculations and Fabrications

Another day of break, another day to work. Today, we met in K2 from 9-7, and completed more of our central design work. We specifically looked at physics and motor calculations for the cascade elevator, as well as layout designs for the power cube intake. Tomorrow, we hope to translate these designs to 3D models in CAD and place our preliminary round of orders.

Now, for the physics. First, our requirements: we know from analysis of previous year's robots that the optimal speed for an FRC linear elevator is roughly five feet per second. Because this speed will be accomplished by the innermost carriage within the elevator, the primary stage will have to travel at a speed of two and a half feet per second, or 0.762 m/s. Our objective is for the robot to scale the scale at this velocity, carrying a load of approximately 70 kilograms. By taking into consideration tentative pulley dimensions, motor specifications at peak power, and knowledge of gear ratios, we were able to determine several important theoretical figures about our climbing mechanism. First of all, the required power needed to climb is calculated to be just over five hundred watts, requiring two 775 Pro motors. However, due to concerns with overheating by running 775 pro motors near peak power throughout the endgame, the team decided to design using four 775 pro motors instead of two. With these four motors. our robot would be able to lift the weight of one other robot attached to ours, easily, opening up options for our strategy team. The main limiting factor in that situation, however, would be our drivetrain acceleration, which could not run at the same time for fear of browning out the RoboRIO. In conclusion, our final decided gear ratios are 25:1, planned for versa planetary gearboxes with a two-motor adapter adapter. 

Next, we prototyped intake wheel arrangements for the power cube manipulator. After surpassing our initial time expectations for prototyping, we revisited the effort with specific objectives. It is only worthwhile to prototype a system if your team would gain something from doing so, and thus we decided continuing our efforts would give us insight into wheel distance for vertically aligned power cubes, as the fabric can deform slightly on one side. We decided to use a spring-tensioned, jointed pair of mirrored sectionally-sigmoidal-shaped arms (hard to explain, think integral sign) with three pairs of high friction wheels, spaced such that the tension is initially able to intake vertically-aligned power cubes, and expands to allow a secure grip on flat power cubes. We expect to calculate free-speeds of the intake before the end of the day, tomorrow, and cut out a rough design of the plates which will eventually mount to the competition robot.

Fabrication is going better than ever thanks to the dedication and time given by our wonderful coaches and mentors. This season, we are on track for a three-hundred hour time commitment, which will be instrumental in testing and prototyping, in addition to the motion of building a second robot. 

Here's to another productive work day ahead!