Applications and implications
The weekly assignment require the description of the final project that integrates the range of units covered during the academy. As described at the beginning of the academy my final project (that will be presented at the Maker Faire 2015) is a robotic fish called “Piske” (fish in Sardinian dialect). The end of the academy approach faster so I decided to focus my attention in the design a fish-like shape 3D printed containing the mechanical and electrical organs and design the emergency system that allow the fish not to disappear in the deep.
WHAT WILL IT DO? “Piske” has been designed in order to swim (using a small DC motor) at a certain fixed depth underwater and checks several parameters (not yet implemented). An emergency system has been designed based on a photo resistor that control the intensity of light (which decreases with the depth of water). At the design depth a switched on green LED indicates the correct placement. If the light decreases (increasing depth) a yellow LED switch on (green LED switch off). If the light continue decreasing (increasing depth) a red LED switch on (yellow LED switch off). At this point (dangerous depth) the lateral fins rotate (servo rotation) and the fish go back to the water surface.
WHO'S DONE WHAT BEFOREHAND? On the web there are a lot of different kind of robotic fishes. Three big families can be defined:
1)Fish that are supposed to swim/to appear in a very realistic way: example one and two 2) Kid games example one, two and three 3) Underwater drones example one and two
Even if there are a lot of robotic fishes around the world, I could not find a fish with sensors (i.e. temperature or pressure), just cameras or complex mechanical systems.
WHAT MATERIALS AND COMPONENTS WILL BE REQUIRED?
WHERE WILL THEY COME FROM?
HOW MUCH WILL IT COST? The fish body will be 3D printed with ABS. Approximately the weight will be 0.5kg. Considering that one roll of ABS costs 35€ and taking into account printing errors, the full amount of 35€ will be taken into account. Price (approximately): 35€
Two servos are needed for the two lateral fins. Price (approximately): 2*5.20€ = 10.40€.
One DC motor is needed for the main engine. Price (approximately): 1.70€.
A main board and a secondary board for input/output devices are required.
The components used for the main board (FabKit) could be find at this page.
Take into account the loss of some components! Price (approximately): 15.00€
The components used for the input board are:
1 RESISTOR Price (approximately): 0.10€
1 SIX PINS HEADER Price (approximately): 1.10€
1 PHOTO DETECTORS Price (approximately): 0.90€
1 PCB Price (approximately): 4.90€
The components used for the output board are:
3 LEDS Price (approximately): 1.00€
3 RESISTOR Price (approximately): 0.30€
At the end of the list, 15€ will be taken into account for wires, bolts, screws and all the secondary parts not directly involved in the design but that can be needed during the process.
The final (approximate) price of the “Piske” is circa 90€.
WHAT PARTS AND SYSTEMS WILL BE MADE? WHAT PROCESSES WILL BE USED? As introduced before the main body and the fins will be 3D printed using the DeltaWASP 40x70cm or a Zortrax M200).
The mentioned boards will be designed using Eagle and then milled with the Roland Modela SRM-20.
The underwater test will be performed in a big tank (if available).
WHAT TASKS NEED TO BE COMPLETED? The main task will be the first assembly of the fish, the check of the above mentioned emergency system by means of an underwater test, even if the underwater equilibrium of all the weights has yet to be improved.
WHAT QUESTIONS NEED TO BE ANSWERED? Will be the fish able to move around the equilibrium position (fixed depth) by modifying the code?
Will the equilibrium of the weights (especially the motor weights) affect the final shape of the fish ?
Will the waterproofing be a too complex problem ?
Design depth will not be set to an high value, but structural deformation of the hull will affect the fish functionality ?
WHAT IS THE SCHEDULE? The schedule is:
• 3D print the body and the parts
• Insert the electronic components
• Light the motors and do the emergency check!
HOW WILL IT BE EVALUATED? The functionality of “Piske” will be evaluated by means of the good result in the emergency check.