P15029: Air Muscle Underwater Fish Phase 2 - Buoyancy

Week 8

Table of Contents

Waterproofing Pump

In order to waterproof the pump, a 3” diameter threaded PVC pipe with end caps were chosen as the housing, as aforementioned. Properly sized holes were drilled into the PVC pipe to allow for access between the environment outside and the pump, which include wires and tubing. It was a concern that those openings, no matter how tight, would allow water from the environment to leak into the pump housing and hinder the performance of the pump, with the worst case scenario being an inoperable pump. As a result of this concern, the openings (tubing and wires included) were covered with pipe cement. See the photos below for clarification.

The test plan below indicates various stages of water proofing the pump and testing that housing, in order to address the above concern. The pipe cement was the primary solution in reducing leaks into the housing. However, there were issues with the pipe cement cracking. This issue was introduced into our problem tracking spreadsheet and has been temporarily resolved by examining the openings with pipe cement before and after testing and reapplying when necessary. This decision was based on the pipe cement’s success in the past. Furthermore, despite some minor leaking, the pump still performed as expected.

Waterproofing Pump Test
S9 Test Plan

Composite Head

After researching various composite materials, it was determined that a marine/boat style composite would be used to form the shell for the main body of our fish, due to its obvious water-usage. The chosen composite was ordered from West Marine. Once the composite arrives, it will undergo various tests to determine molding technique and coloring. The support of an RIT professor, Dr. Ghoneim, has been confirmed in the creation and implementation of a mold for this composite.


Electronics Prototype

A working electronics prototype for the valves, air muscles, ballast tank and pump has been assembled using breadboards and an Arduino. Also, initial programming has been performed in conjunction with the testing of the electronics and the aforementioned subsystems. This initial prototyping demonstrated successful integration between electrical and mechanical subsystems.

Electronics Prototype

Distance Sensor Waterproofing

The short range IR distance sensor was waterproofed using Plasti-Dip. The waterproofing was then verified by testing the IR sensor while submerged in water. It continued to work as expected. Upon successful waterproof testing of the short range IR sensor, the decision was made to go ahead and waterproof the long range IR sensor, which will be the actual distance sensor implemented in the fish.

Tail Motion Testing

The tail segment and air was successfully attached to the body channel, along with its corresponding air muscles configuration. The air muscles and tail segment were fully integrated with one another by wiring each muscle to its joint counterpart within the tail. The success of this wiring was demonstrated during prototype testing in MSD I. Below are photos of the tail segment with its wires in place.


The tail motion was then tested by integrating the above components with the electrical prototype. See Test Plan S3 for more details for The following images show the correct swimming motion of a fish. Further testing will need to be done to perfect the fish swimming motion. However, this initial integration has proven that the subsystems aforementioned can successfully collaborate.

Tail Motion

Full Set-Up

The electronics prototype and the mechanical subsystems were fully integrated and tested in this phase of MSD II. The following images show the overall fish structure, with all mechanical subsystems connected, with the electronics prototype wired in where they are necessary. The water bottles were used to achieve neutral buoyancy and help with floating for testing purposes. The water bottles will later be replaced with pool noodles and various weights to achieve stability and neutral buoyancy. The fish was then tested in the Tow Tank at RIT for tail motion, buoyancy, pump leakage, and valve integration. (These specific tests and subsystems have been detailed above).

Full Fish Set-Up

Problem Tracking


Updated Project Plan


Table of Contents MSD II

Week 5 Week 8 Week 11 Week 14

Ballast Tank Testing

Skin Color Testing

Tail Motion Testing


Waterproofing Pump

Composite Head

Electronics Prototype

Tail Motion Testing

Problem Tracking

Updated Project Plan


Communication System

Swimming Algorithm

Electronics Hardware

Air Muscles

Buoyancy System

Eco-Flex Skin

Problem Tracking

Schedule to Imagine


Performance vs Requirements

Imagine RIT

Final Videos

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