Chewbacca and the Ewoks are trapped inside an Empire stronghold! Scooter, our autonomous robot, must navigate the course shown below and bring them back to safety.
To do so, it must:
- Follow a trail of black tape
- Detect, grab, and store 4 Ewoks
- Cross two 6 inch gaps (the second also 2″ in height)
- Detect and characterize different frequencies of IR signal
- Follow the edge of a bridge
- Return the Ewoks to the start area down a zip line
Full competition rules can be found here.
On the left is a diagram representing all obstacles and components of the competition surface. On the right is a 3d model of the course.
Available Tools
To complete these tasks, a number of tools and materials were made available to us. We had access to two 3D printers, a laser cutter, a water-jet cutter, the UBC physics machine shop, steel, aluminum, and brass, Delrin, acrylic, hardboard, wood, a variety of microcontrollers, electrical and mechanical components, wires, soldering irons, etc.
Results and Reflections
On August 9, 2018, Scooter competed against 15 other robots and placed 4th. The main issue Scooter had was reliability. Due to variations in positioning, it would not reliably grab one of the Ewoks or put the basket on the zip line every run. Scooter’s tragic loss resulted from his position being ~5mm to far forward and the hook for the basket getting stuck under the zip line.
Looking back, additional sensing to help Scooter better localize himself on the course would have been crucial to improve his performance. Rotary encoders could have been included to provide feedback for the motion of the DC motors. Encoders would also allow us to calculate a value for motor torque, letting us detect potential jams/drivetrain issues, identify when the robot had hit the zip-line, and adjust power to compensate for different inclines on the course. Another approach, that we initially considered, but was ruled out due to the additional cost would have been to use stepper motors on the drive train to get precise open loop motor control, unachievable with conventional DC motors.
To highlight the importance of reliability, here is a sped up practice run where Scooter’s performs perfectly, but his basket was slightly too high to properly hook over the zip-line, costing him 11 out of 17 points!
Scooter 