P16029: Robofish 3.2 - Object Retrieval
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Preliminary Detailed Design

Table of Contents

Team Vision for Preliminary Detailed Design Phase

Tasks for this Review

Tasks for this Review

Timeline and Completeness

Timeline and Completeness

System Flow Chart

Overall System Flow Chart

Overall System Flow Chart

Image Processing

In this phase we started looking into the different options for cameras that could be implemented for the image processing, the two primary options were either a regular webcam, or one with a fisheye lens. In order to get a better idea of which camera is better for our system, the field of view of both were calculated. Further discussion is needed, but in terms of cost effectiveness and ease of implementation, the regular webcam appears to be the better option.

FOV Estimates

FOV Estimates

Utilizing the input from last review, the algorithm for detecting the object was modified to now identify it using color versus "teaching" the program what the diving stick looks like. The use of tracking the color allows for greater versatility of the program, because now it can track any object as long as it has been set for the appropriate color.

Object Detection Algorithm

Object Detection Algorithm

To determine the distance to the of the object, it was chosen to use the relative size of the known object at known distances to create an equation that when inputted the pixel width will give the relative distance of the object. This was tested with measuring the size of the object every two inches until the object was three feet away, and the given data for the current setup resulted in the equation in the graph below. When the equation was put into the program it outputted distances within two inches of the correct distance.

Distance Using Width in Pixel

Distance Using Width in Pixel

Hydraulic System

We have changed our hydraulic system to a simpler design. Instead of using a compressed air tank to force water back out of our ballast tank, we will use a series of valves that can redirect the flow from the pump. This lets us draw water from the environment to fill the ballast tank, or draw water from the ballast tank and push it back into the environment.

System Hydraulic Schematic

System Hydraulic Schematic

We ordered a pump that provides 5 L/min of flow and a max pressure of 100 psi. We were unable to create an experimental pump performance chart due to the difficulties of measuring the pressure of a diaphragm pump. However, we did measure the flow rate through one of our valves to be 2.6 L/min, which corresponds to 48 psi of pressure on the theoretical pump performance graph.

Pump Performance

Pump Performance

Using this initial pressure and the slope of the pump performance graph, we modelled how the ballast tank would fill over time as the air inside it was compressed. From there, we estimated velocity, depth, and the time to intercept a sinking object.

Intercept Calculations

Intercept Calculations

By changing the size of the ballast in the calculations above, a chart of the time needed to intercept a sinking object at two different speeds was generated. Based on this chart, we were able to determine an appropriate size for the ballast tank.

Ballast Tank Size

Ballast Tank Size

Buoyancy Control

Fill and Drain functions

Fill and Drain functions

Buoyancy Control Flow Chart

Buoyancy Control Flow Chart

Method1: Hydraulic Mock up

Method1: Hydraulic Mock up

Method1: Current Pulled by Mock up

Method1: Current Pulled by Mock up

Method2: IN-3/8

Method2: IN-3/8", OUT-3/16"

Method2: Current Pulled by IN-3/8

Method2: Current Pulled by IN-3/8", OUT-3/16"

Method3: IN-3/8

Method3: IN-3/8", OUT-3/8"

Method3: Current Pulled by IN-3/8

Method3: Current Pulled by IN-3/8", OUT-3/8"

Each Methods'Performance

Each Methods'Performance

Jaw Design

Jaw Design - Front

Jaw Design - Front

Jaw Design - Back

Jaw Design - Back

Jaw Design - Side/Bottom

Jaw Design - Side/Bottom

Why did we choose this design?

Return Home

RSSI was monitored for 450ms then histogram was generated.

Variation of RSSI at a fixed distance of 3m

Variation of RSSI at a fixed distance of 3m

Histogram of RSSI variation

Histogram of RSSI variation

Simulation of approaching "Home" was conducted by moving cell phone towards the beacon in constant speed. It indicates that "Home" location can be approached by using RSSI of a single Bluetooth beacon within 5 meter radius.

Observed RSSI variation as Fish moves towards Home

Observed RSSI variation as Fish moves towards Home

Histogram of RSSI variation

Histogram of RSSI variation

Testing Magnetometer

Testing Magnetometer

Bill of Material (BOM)

Confirm that all expenses and contingencies are afforded by the project financial allocation.
Bill of Materials

Bill of Materials

Fish CAD Model Design

A rough CAD model was assembled to give us an idea of how big the fish body would need to be. The current design is 12" tall, 8" wide, and 20" long.

Fish Assembly - Front

Fish Assembly - Front

Fish Assembly - Top

Fish Assembly - Top

Fish Assembly - Bottom

Fish Assembly - Bottom

Risk Assessment

Updated Risks Added

Updated Risks Added

Plans for next phase


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