Summary

The Surfbot is a programmable mechatronics device that applies a coat of wax onto a surfboard based on a user’s preferred waxing pattern.
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It utilizes 2 stepper motors to control a compliant wax-head that applies a consistent wax coat over uneven contours. The system uses an Arduino to control it and a closed loop controller was designed to assure accurate path tracking.

Hardware & Software

Wax Holder:

• 3D printed plunger assembly with internal spring to maintain constant normal force between the wax and board

Structural:

• 80/20 Aluminum Extrusions
• Custom machined 6063 aluminum crossbar

Linear Motion:

• 20mm hardened steel rails with linear bearings
• T8 lead screw system​​

Mechatronic:

• 2 Stepper Motors
• Encoders
• Arduino
• Raspberry Pi

Using an Arduino Uno, rotary encoder, and Rasberri Pi, the surfboard waxer implements a closed loop feedback control system.  By pulsing to the motor drivers and reading wax head position, a PID controller was implemented via communication between the Rasberri Pi and the Arduino.

This feedback controller ensures that the various trajectories of the wax head are robust when subject to disturbances, resulting in the most even coat of wax. A linear quadratic regulator was designed using the premise of impedance control for implementation in the further design iterations of the waxer, in which the actuated wax head shifts automatically to a position which provides a predicted level of contact required between the board and the wax. This allows for adequate coverage given changes in board shape, board curvature, and surface friction from previous wax layers.

Acknowledgments

A huge thank you to the entire team (JT Truitt, Julie Steigerwald, Kelcie Bourne, Richard Didham, Nathan Penn), to GSI's Andrew Barkan and Patrick Savidge for the guidance, and to Professor Kazerooni for leading this course!