Mechanical Design


With four distinct actions involved in winning the game (exploring the field quickly to obtain easy exploration points, spinning a gearbox to capture a territory, pulling a lever to dispense resources, and delivering the resources in the center of the field to score massive points), we took a simple approach to designing our robot: build mechanical systems for each of the tasks. Our robot is split into two main systems: Drive (allows the robot to navigate the field) and Articulation (allows the robot to interact with the field).


Drive

We decided to only use two motors for our drive, as extra DC motors were costly in sensor points. Before building, we performed a few calculations to optimize our gear train. First, we weighed several winning robots from previous competitions for an estimate of an average robot weight. Using this weight, the radii of Lego wheels, and the given specifications of the DC motors, we calculated our desired torque needed to move our robot at a competitive speed. We also used the provided motor curves and designed our gear ratio to have a normal operating torque at two thirds of peak efficiency. This allows our drive system, in the event of a collision with a field element or another robot, to become more efficient as the motors apply more torque. Our final gear ratio was 125:1.


Articulation


The gearbox spinner is located on the backside of the robot, using a DC motor on a 25:1 gear ratio to spin a large Lego wheel. The large, single Lego wheel allows us to approach the gearbox at many angles without missing.


The lever pull mechanism is stationed on the front of our robot, utilizing a four-bar linkage (so that the puller maintains a constant angle) on a 1:1 servomotor. The use of the servomotor enables us to set certain positions for the lever puller, which allows us to be precise in dispensing resources. The lever puller at its highest state can actually push the bucket dump (which will be explained next) up and increase its slope in case a resource fails to escape.


Lastly, the bucket dump system rests on top of the main chassis, pivoted near the backside of the robot. At the backend of the bucket is a chained 1:1, servomotor-operated gate, allowing balls to be stored and then dumped at an appropriate time. The gate allows the bucket to span only a fraction of the chassis length, as the gate can extend down and bridge the remaining length of the robot to the dumpsite.


BOTT SCEZEK   

team 2

Gearbox spinner.

Lever puller.

Bucket dump.