In essence, the final prototype of our unmanned remotely controlled boat, Clear Water, comprises of 2 essential (involved in tackling an environmental issue – namely floating waste on bodies of water) features which are the floating waste capture mechanism as well as the on board storage enclosure for said captured waste.
The Two Essential Features of Clear Water Below
1. Floating Waste Capture Mechanism
Materials/Components & Their Specifications
Non Electronics Related Components Below
(#1) 2 x high density polyethylene (HDPE) mesh net piece
Dimensions: 90 cm in length x 30 cm in width
(#2) 3D printed pulley system made of polylactic acid (PLA)
(#2.1) 2 x column piece and its accompanying base piece connected to the rest of the frame of the hull
(#2.2) 1 x double T shaped looking piece connected to 1 x U shaped looking piece
(#2.3) 2 x pulley piece that looks like a shaft with a sleeve on it
(#3) 2 x jute string acting as the pulley’s belt
Electronics Related Components Below
(#4) 1 x 12V 24 RPM with peak torque 15 kgfcm (1.47 Nm) brushed DC geared motor
Weight: 300 g
(#5) 1 x L298N Motor Driver
Weight: 20 g
(#6) 1 x ESP32
Weight: 25 g
(#7) 1 x 11.1 V 1300mAh Li-Po Battery
Weight: 200 g
(#8) 8 x AA Alkaline Batteries connected in series in its holder with On/Off switch and cover
Overall Weight: 400 g
(#9) Several Male to Male and Female to Female Jumper Wires of various lengths
Miscellaneous Components
(#10) 1 x PVC Pipe
Dimensions: 3.5 cm inner (hollow) diameter & 13 cm length
(#11) 1 x Plastic Container
Dimensions: 17 cm length x 11.5 cm width x 8.5 cm height
Software Used
(#12) Robotic Operating System Command Line User Interface (running on Linux OS laptop)
Description of Waste Capture Mechanism
(#1) When the boat moves towards floating waste on a body of water, some the floating waste will settle and be temporarily trapped on the two pieces HDPE mesh net which will act as two individual platforms for collecting floating waste.
(#2) The two pieces of HDPE mesh net are able to be lifted up simultaneously towards either side, where said waste will then be dumped onto either side of the on board storage enclosure for temporary keeping. The motion mentioned will look like the lid of a roof hatch opening. This motion will be controlled by a single high torque motor which will allow it to lift a large amount of floating waste that is collected onto the platform. Moreover, this motion is also possible due to the pulley system and the pulley belt employed.
(#3) Once the boat operator deems that the two platforms have been lifted high enough whereby all the waste collected on the platforms have fallen into the waste storage enclosure, the operator will reverse the direction of the pulley on a Linux OS laptop containing the Robotic Operating System command line user interface.
1.1 Floating Waste Sweeping Mechanism
Our boat has a rear non-rigid mesh net (which will be elaborated on below) that is perpendicular to the surface of the water and can allow floating waste that is trapped on the surface of the water to be pushed out by said net towards the shoreline
2. On Board Storage Enclosure for Captured Waste
Dimensions of our HDPE mesh net acting as storage enclosure barriers are as follows:
(#1) Front and Rear Barriers: 26 cm height x 20 cm width
(Both barriers installed on both sides of the boat)
(#2) Side Barrier: 26 cm height x 79 cm length
(Side barrier installed on both sides of the boat)
(#3) Base: 73 cm length x 26 cm height
(Base installed on both sides of the boat)
Our on board storage enclosure is essentially made up of high density polyethylene (HDPE) mesh nets that are typically used for gardening and fencing operations. However, it still fits our use case and can act as barriers (walls) of our storage enclosure to prevent collected waste from easily escaping our boat. We mainly tested whether plastic bottles and empty potato chip cans will easily escape our storage enclosure and I am delighted to inform you that they can all stay in place in the storage enclosure once it has been dumped there. Therefore, if we narrow the scope of the floating waste we can capture, then our storage enclosure works perfectly fine for your typical plastic bottle sized floating waste. We reckon that our storage enclosure can store a total of up to 30 – 40 empty plastic bottles (~ 500 ml each) before our storage enclosure becomes too small to fit anymore empty plastic bottles. The weight due to these 30 – 40 empty plastic bottles (~ 300g – ~ 400g) is still sufficient for the base net to handle without sagging considerably.
The 4 main benefits of HDPE mesh nets are as follows:
- Relatively non rigid and hence it can be easily deformed. Hence, it can be easily positioned according to our needs.
- Corrosion resistant
- High strength
- Durable.
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However, in order to allow for proper operation of our boat, there are what we will deem as non essential components (assembled together) which are nonetheless required in order for Clear Water to function as an unmanned remotely controlled boat.
Non Essential Components Below
Structural Components (Frame of the Hull)
(#1) Many 3D printed PLA pieces of different shapes, sizes and use cases
(#2) 2 types of PVC pipes with one having the dimension of 1.3 cm in inner (hollow) diameter and the other having the dimension of 3.5 cm in inner (hollow) diameter and both in various lengths
For Buoyancy Purpose Only
(#3) 4 x Ethylene-vinyl acetate (EVA) swimming kick boards
Attaching many disparate pieces of the boat together
Attaching disparate 3D printed parts and the frame of the hull
Many of the disparate 3D printed parts are connected to one another via push fit. As such, none of the disparate 3D printed parts are permanently joined together and hence the entire boat or parts of it can be fully disassembled relatively easily. Moreover, we can modularize certain parts of the boat for easier storage and transport when needed, instead of being forced to deal with the entire boat as one large piece. Last but not least, the fact that we utilized a push fit connecting system means that the connection between disparate 3D printed parts can be more easily adjusted when need be. For instance, the 3D printed L shaped joints (with dual connecting heads) that controls the smoothness and speed of the pivot of the aforementioned mesh platform lifting motion (part of the waste capture mechanism) can be adjusted accordingly. We can insert deeper or pull out more of the connecting head that is connected to the socket which are the PVC pipes, in order to adjust the overall width of the mesh platform. Furthermore, we can adjust the tightness of the push fit by wrapping some tape around the connecting head if we deem the fit to not be secure enough. We 3D printed sockets and connector heads with dimensions that allow a minute degree of freedom in the push fit. As a result, the push fit is never “spot on”, whereby once you attach two or more compatible pieces together, it will be extremely difficult to separate them without potentially causing damage or outright breaking said piece(s), because the fit is simply too tight and secure.
The frame of the hull of our boat is made up of only PVC pipes and various 3D printed parts all connected once again via the versatile push fit system. Unfortunately our boat does not possess a typical hull structure where there is an actual continuous body of the hull present. Thus, we call the body/hull of our boat the frame of our hull. Our boat resembles more of a flotation device that is made up of “skeleton” looking components.
Attaching pieces of the mesh nets to the frame of the hull
The mesh structure of the net inherently offers sufficiently large holes for cable ties of 3 mm & 5 mm both in width to be slotted through in order to fasten the mesh nets to a particular section of the frame of the hull. The tightness of the cable ties fastening can be adjusted accordingly. Moreover, we can always utilize more cable ties when necessary in order to provide even stronger fastening. But the same cannot be said for chemical adhesive which will not provide stronger fastening when more and more of it is being used. Last but not least, cable ties do not possess any chemical adhesive substances and hence we do not need to worry about any chemical adhesive residue if we reposition pieces or already attached pieces come loose. Therefore, we believe that cable ties attachment system for mesh nets in particular is superior to any chemical adhesive solution.
Propulsion System Through Water
(Work in Progress Unfortunately Due to Complications)
Materials/Components Used
(#1) 2 x brushless DC (BLDC) motors with propellers for underwater usage
This BLDC motor is capable of spinning in 2 directions so one direction will be for forward motion and the other direction will be for backwards (reverse) motion.
We can vary the speed of one of the BLDC motor while keeping the other BLDC at a fixed speed and this will allow the boat to navigate turns.
Unfortunately, most likely due to incorrect programming codes, we are unable to get the BLDC to run as desired.