F.E.T.C.H.

Our drive system was designed to supply our robot with enough torque to navigate the course, driving up the hill under full weight of the robot and animals, while also doing this with as much speed as possible. To achieve this, we drove our rear wheels with two ungeared motors, put through an additional 5:1 gear reduction. We adjusted the wheel size and the gear ratio, eventually settling on four inch wheels that allowed for a high speed and sufficient torque.

To use this torque as effectively as possible, we tried to minimize friction in our drive system as much as possible. We mounted our gears on motors on removable brackets that were carefully cut from steel and bent to be well aligned. We also machined brass bearing surfaces to reduce friction in the interface between our chassis and our drive shafts. Our gears were laser cut from acrylic and delrin, to employ the precision of laser cutting, and the durability of delrin in our gear interface.

For our approach we needed an arm capable of picking up pets on both sides of the robot, traversing an angle of 180 degrees. To achieve this, we built a servo arm using a high torque motor, and a potentiometer that gives feedback to the motor so that we can determine the exact position of the arm. We drove the main arm with a worm gear to gain a large increase in torque, and to use the worm gear's ability to hold the arm at an angle without driving the motor. We manufactured the gear box, arm supports and arm mount using a variety of fabrication techniques, including 3D Printing, waterjet cutting, and laser cutting. The precisely assembled arm and gearbox allowed us to reduce friction enough that our arm ran reliably, never got stuck, and matched given angles precisely.