Raider of the Top Mark
Our robot - Raider of the Top Mark - combines existing engineering solutions to tackle the given challenge in a simple and effective design.
To have high torque and allow for driving up a ramp and over rocks, we constructed a drive system with a 7:1 gear ratio. The gear system was mounted within the wheel, as shown in the video.
Drive System
Raider has three main features that uniquely designed for the competition: large wheels with high torque, a sled instead of front wheels, and a simple single actuation retrieval arm.
The wheels were made from scratch with the following components:
-
Gears and Spacers - laser cut 6mm acrylic
-
Wheel Disk - waterjet cut plywood
-
Bearing - 3D printed
-
Rims - waterjet cut and spotwelded steel
-
Treads - waterjet cut rubber and pipe insulation
Front Sled
Although unconventional, the front sled proved to be a great design for allowing the tape following reflectance sensors to always be a close distance from the tape, providing mechanical dampening while steering, and most importantly, pairing with the large diameters wheels to glide across the rocks effortlessly (as seen in the video). The key behind its success was to shift the robot's centre of gravity as far back as possible to minimize normal force on the sled.
The sled was waterjet cut and hand bent into shape, with a small aluminum rod connecting it on a hinge to the underside of the chassis.
Retrieval Arm
The most important aspect of our robot is also one of the most simple. The arm extends from the side of the chassis to hover a steel plate reinforced with strong magnets at the exact distance and height of the artifacts. Because the robot is able to tape follow so well, the steel plate always comes in contact with the magnetic top of the artifact, which triggers a thin plate on a hinge to press a microswitch between the thin plate and steel. The arm then completes its simple RC servo motor single plane motion to swing the artifact inside the chassis where mechanical objects simply dislodge the arm's magnetic hold. This can been seen well in the video at the top of the page.
The arm is made of the following components:
-
Main extension - thick waterjet cut aluminun
-
Magnetic plate - hand cut steel
-
Trigger hinge plate - thin hand cut aluminum
-
Hinge - plastic cylinder
