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The Wicked Winch

An autonomous-driving ball-launching robotics capstone project

My baby

The Project

In January 2016, the UCLA Mechanical Engineering Senior Class was split into groups of five, and assigned a task:

Create a robot that
  1. Is completely autonomous
  2. Can navigate a twisty and hilly course
  3. Can launch a golf ball precisely 4 feet +/- 10% from the end of course
  4. Can traverse the course back to the starting point
  5. Uses active steering
  6. Can do this in under 2.5 minutes
  7. Fits within an 11” x 11” x 11” volume
  8. Costs less than $375

The Course


The Best Team Ever


Design

We had to make some critical design decisions early that would affect our process thereafter.

  1. Number of wheels
    • We went with three wheels. The two rears can be powered through a single axle. The front steering wheel can be actively steered with a servo.
  2. Sensor placement
    • Left and Right sensors located near the centerline, forward and rear sensors angled downward.
  3. Launch mechanism
    • A wicked winch that loads a spring and quick releases a piston that pushes the ball out and up.
  4. Drivetrain
    • Belt-driven solid rear axle.

Computer Aided Design

We had to have an accurate CAD by the end of 162D, which we would then build during 162E.

Full Solidworks CAD


Solidworks CAD of the Launching Mechanism

Building & Programming

The launching mechanism was a half gear which, via a geared winch and fishing line, loaded a spring inside the barrel and pulled back the piston and ball-carriage.

Launching mechanism, without the release


The pyhsical product


The brains of the robot was a school-provided NI MyRIO, which – of course – had to be programmed in LabView


A statechart was used to step the robot through the phases of its journey


The Results

We built the robot to spec, and managed to use only $275 in parts, $100 under budget! At the final competition, it performed its task 3 times in a 5 minute window, without any adjustments or resets!

A clean practice run in the lab! The golf ball hits the target!