Subsystem Build & Test
Table of Contents
Team Vision for Subsystem Level Build & Test PhaseDuring 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 ModelThe 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.
Centers of Mass and BuoyancyUsing 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.
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 DesignThe 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.
Hydraulic SystemOur 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.
Bluetooth Communication and Locate HomeBluetooth 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.
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 MaterialsInclude links to:
- Presentation and/or handouts
- Notes from review
- Action Items
Plans for next phase
- PVC Caps Machined 2/25/16 or 2/26/16
- Build Start Date: 2/28/16 (Body and Ballast Tank)
- Electrical Integration week 6 (2/29/16 – 3/4/16)
- Machine and Assemble Pump Case and Jaw: week 6
- Jaw will be printed by the end of week 6
- Week 7 we plan to start testing:
- Buoyancy Testing
- Max Depth Testing
- Jaw Grip Strength Testing
- Under Water Imagine Processing
- Potential to have full fish assembled with valves by week 8’s presentation