Embedded Files
Drivetrain
Drivetrain
Our team chose a circular design for our robot in order to increase agility and maneuverability. By placing the wheels at the centerline, we ensured that the robot would only turn in its own shadow and would not hit the wall while searching for beacons at startup. The drivetrain of the robot consists of metal axle supports, rollerblade wheels, metal wheel inserts, D-shafts, flexible couplers, 3D-printed motor clamps, the provided motors and encoders, and the encoder holders developed by previous students. The axle supports and couplers help to ensure alignment of the wheels and prevent harmful radial forces from being applied to the motor. The robot also features two caster wheels, one at the back of the robot and one embedded in the bottom of the “spoon.” These caster wheels were placed slightly higher than the base of the driving wheels in order to prevent them from lifting the driving wheels out of contact with the ground. By placing the heavy batteries in the back of the robot, we were able to ensure that the robot would balance mainly on its back caster wheel. The front caster wheel guaranteed that the “spoon” would glide smoothly even if it were forced into contact with the ground, and it ensured that the robot could not tilt too far forward if something were to go wrong with its balance.
Feedback and Control Shelf
Feedback and Control Shelf
The third tier of the robot provides the fixture points for the gameplay LED (which indicates when the robot is actively playing a round), the yard servo (which indicates which side of the field the robot is located on), the power switch (which provides an emergency shutoff), and the idle/game switch (which initiates gameplay). We chose to use a large LED for our gameplay indicator because it was simple to incorporate and highly visible. We chose to use a servo with a 3D-printed arrow to indicate the yard because it was straightforward and legible.
Spoon Assembly
Spoon Assembly
The striking mechanism of the robot is made up of a DC Motor, two plastic gears, and the 3D-printed “spoon.” The 50:72 gear ratio turns the output of the motor from 170 rpm to 244.8 rpm. The spoon is attached to the baseplate of the robot using a shoulder bolt and an assortment of bearings and spacers found in the lab. The spoon is designed to cup the pucks, so that when it strikes pucks from underneath the trees, the pucks are launched at a diagonal towards the back of the robot instead of being pushed perpendicular to the wall, where they would run into the edge of the fence.
Sensors
Sensors
The phototransistor for beacon detection was mounted in an adjustable slider in order to permit height tuning. The two ultrasonic sensors (one pointed forward for tree proximity and the other pointed downward for wall proximity sensing) were located at the front of the robot using a hinge and a 3D printed scrap from the lab to speed up fabrication, to increase ease of adjustments, and to allow for earlier testing. The proximity sensor used for locating the initial acorn was also mounted on a hinge found in the lab in order to permit exact calibration of the optimal angle for detection. The robot was originally designed to also include an IR emitter and detector for use in locating acorns across the field, but there was not time to implement this feature. On the bottom of the robot, the tape sensor is suspended between the two encoder mounts in order to sense the location of the center of rotation of the robot.
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