P16029: Robofish 3.2 - Object Retrieval
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Subsystem Build & Test

Table of Contents

Team Vision for Subsystem Level Build & Test Phase

During this phase the team purchased and finalized the selection for last minute selection of parts and supplies. The most challenging subsystems that had been giving problems to some preliminary testing were the valves. The main body components were machined or are currently waiting to be machined. Building and Testing dates have been assigned.

Risk and Problem Tracking

Updated CAD Model

The CAD model has been updated to include the most recent tail and jaw designs, and to incorporate a slightly larger case for the battery packs and circuit boards.

The latest files can be downloaded here.

Robofish Model

Robofish Model

Centers of Mass and Buoyancy

Using SolidWorks, the centers of mass and buoyancy were calculated. These approximations take into account the volume of air enclosed in the battery and pump cases, as well as the water in the ballast tank. A comparison of the two points can be seen below.
Center of Mass

Center of Mass

Center of Buoyancy

Center of Buoyancy

Values

Values

Because the center of mass is located above the center of gravity, it is likely that the Robofish will try to flip belly-up. Foam will be added to the top and additional weight will be added to the bottom of the design as necessary to keep the Robofish upright.

Jaw Design

The design of the jaw has been finalized. It utilizes a torsion spring to close the claw and will be pulled open by a wire attached to a McKibben muscle. To prevent the jaw prongs from slipping on their axles, flats will be machined onto shaft collars, and the collars will be set into the prongs.
Jaw Design - Isometric

Jaw Design - Isometric

Jaw Design - Front

Jaw Design - Front

Jaw Design - Detail

Jaw Design - Detail

Hydraulic System

Our Robofish design reuses many of the valves from Team P15029's design. However, the addition of a jaw means there is an extra muscle that must be operated. The goal of catching a sinking object also requires a more responsive ballast tank. An extra 3-way valve for the jaw muscle, and two 2-way valves with larger internal orifices (and therefore higher flow) have been ordered from Triline.

The hydraulic design has also changed to use a pre-charge ballast tank with a passive draining system, rather than an active draining system due to the difficulty of finding a suitable 4-way valve. The overall schematic is shown below.

Hydraulic Schematic

Hydraulic Schematic

Bluetooth Communication and Locate Home

Bluetooth communication has been tested and confirmed that we will be able to execute specific task on command. Xbee was also able to transmit Lidar sensor value to the computer in real time which shows that we will be able to debug through Xbee communication as well.
Matlab Code for Xbee

Matlab Code for Xbee

9DOF to Xbee

9DOF to Xbee

Lidar to Xbee

Lidar to Xbee

Video for BLE(Bluetooth Low Energy) beacons has been uploaded to the SVN folder and codes for test that were conducted above has been uploaded to Google Drive.

Functional Demo Materials

Include links to:

Plans for next phase


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