A holistic approach to problem solving… The competition Challenge

 

Meet the Team and the Sub.

The 2018 competition

One Problem, Three Solutions

The 2018 Autonomous Underwater Vehicle Competition challenged the  team to complete tasks never attempted before; autonomously retrieve golf balls from 12 feet underwater. These 3 solutions gave the software and electrical sub-teams the space to develop successful techniques to solve the challenge considering technological capabilities and time constraints.

Bilge Pump Suction 

This iteration of design utilizes suction from a 24V 500GPH bilge pump. This pump was chosen due to its reliability, suction power, factory waterproofing, and simplicity in software operation. However, due to the nature of the problem, successful retrieval of balls was only achieved using a random search pattern over the designated ball-retrieving area.
Robust prototyping and testing to determine effective volume in which balls could be actuated
An analysis of the suction pump yielded a volume of 8 cubic inches where the nozzle exerted a sufficient suction force to retrieve the balls. 
FEA gave insight on stress concentrators and possible failure surfaces. Appropriate design adjustments were performed to ensure structural durability. This design was chosen to be manufactured out of Polycarbonate using 3D printing.

Bungee Tension

This design uses the movement of the submarine to descend onto a platform and with the usage of a grid-like set of bungee cords the golf balls were acquired. This design utilizes a previously existing compressed air manifold to actuate a pneumatic linear actuator to push the balls out to release them. 
The beauty and simplicity of this design made it the most successful out of all the previous design iterations.  With a success rate of over 90% in the capture maneuver, this design was chosen for competition. In addition, using previously created electrical actuation boards for pneumatic valves and pre-existing code, the design decreased complexity within all sub-teams
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T200 Thruster Suction

This design iteration utilizes a Blue Robotics T200 thruster to generate outstanding suction capabilities. However, with non-integrated ESC’s, hardware limitations on thruster operations prevented its usage during competition. The effective actuation volume created by suction from the thruster was much larger than the bilge pump previously shown, approximately 15 cubic inches. 
  • The operation of this design involves a pneumatic linear actuator as a stopping mechanism for the golf balls. 
  • This design uses a similar attachment method as the bilge pump design due to successful placement of the nozzle within the submarine assembly

ESC Waterproof Enclosure

Design and Manufacturing

 The development of a waterproof enclosure where all the thruster Electronic Speed Controls (ESC) boards could be stored was necessary for the 2018 RoboSub competition. Due to the heat generated by the boards, I designed and manufactured an internal tray system along with the waterproof enclosure shown. The following features were fitted into design:
  • Lightweight internal mounting shelf assembly with integrated fan and heat sink system for improved cooling capabilities
  • Double bore O-ring seal to prevent water leaking. This increased redundancy in key design parameters such as waterproofing
  •  Anodized Aluminum shell to increase heat conductivity and prevent oxidation.
  • 10mm Blue Robotics cable hull penetrators with O-ring face seal. Precision machined to prevent leaks.

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Competition Environment.

In a rapid-paced high stress scenario such as a design competition, creativity and adaptability are a pre-requisite for success. Things never go as planned. As a Mechanical Engineer, my competition role was to ensure that all the systems worked as they are intended. 
Even after countless testing hours, things don’t go as planned. No time to pondering, its time to do. I found myself manufacturing waterproof cables and connectors, using OTS cables, wire mesh shielding, shrink-wrap, and a lot of hot glue. It worked. Lessons learned: plan for system hiccups and create strategic connections among peers. Leverage your connections for resources and advice, it always helps.
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Testing.

There is never enough testing.  Dealing with timelines, deliverables, and competition deadlines is not easy. Time is not always available. Developing strategic testing strategies and Gantt Charts, along with other management tools, proves pivotal in time sensitive situations. Ensure that the testing is relevant and applicable to the issue at hand. Not all water is equally clear, not all walls are white, not water is equally dense.