The design and development of quad-copter based unmanned underwater and aerial vehicle.
The vehicle electronics pressure casing has been designed and fabricated using acrylic material which can withstand an atmospheric pressure in aerial condition and 10 bar external pressure in underwater condition to fly in both aerial and underwater condition up-to 100 meters.
The brushless DC motor and aerial fixed pitch propellers combination have been selected for the quadcopter type vehicle and each motor is capable of producing a required thrust force for aerial as well as underwater condition.
This type of vehicle will be used in both civil and military applications for surveillance in the air and underwater conditions etc.
NOTE: This is our first prototype in HYBRID DRONE
Step 1: Component Selection (MECHANICAL COMPONENT)
NOTE: Component selection based on your wish and also you can calculate vehicle payload based on components.
- Acrylic Block - 170*170*50mm
- Acrylic tube - ID=25mm, OD=30mm, L=140mm
- Acrylic tube - ID=150mm, OD=160, L=150mm
- Acrylic cylinder block - D=50mm, L=200mm
- Chloroform (or) anabond
- O-Ring- (2 quantity)
- Propeller adapter- (4 quantity)
- Aerial Propeller Counter Clockwise (CCW) - 10x4.5 _ (2 quantity)
- Aerial Propeller Clockwise (CW) - 10x4.5 _ (2 quantity)
NOTE: The propeller length increases the thrust force increases for the aerial condition. When as the increases in propeller length decrease the thrust force in underwater condition.
Step 2: Component Selection (ELECTRONIC COMPONENT)
NOTE: Component selection based on your wish and also you can calculate vehicle payload based on components. The required thrust force is most important thing to take off the vehicle.
- BLDC Motor - (4 quantity)
- The BLDC motor selection is most important. The motor selection based on how much of thrust it will be delivered and to check motor specifications.
- Total payload based to select motor e.g: total payload (3kg)/(motor quantity= 4) =0.75kg* (factor of safety=3) =2.25 kg.
- The motor selection based on thrust value is above 2.25kg.
- Apply hydrophobic coating in BLDC motor to avoid corrosion.
- Electronic Speed Controller (ESC) - (4 quantity)
The ESC is selected based on the high current value then compare to motor maximum current.
- Signal transmitter and receiver
- flight controller -ArduPilot APM, Pixhawk etc
- Lithium polymer battery
- The battery selection based on vehicle motor power required in maximum condition
- LED strip
Step 3: DESIGN
The vehicle design based on aerodynamic, hydrodynamic and material properties etc.
The fusion 360 software platform will be used to design the vehicle for required thickness.
The vehicle design thickness based on material properties and vehicle has been withstanding underwater pressure 10 bar in 100meter condition
- Cylinder and X-tube frame
- End caps
- Motor base
All dimensions are in meters.
Step 4: FABRICATION
NOTE:If you have 3D printing machine easily you can be fabricated.
Fusion 360 software is used to design the vehicle in 3D model to converted in 3D file (STL)
Using 3D printer to upload the file and then you can be printed your vehicle.
If you can use 3D printing machine based on the filament properties you can change the vehicle thickness to withstand the underwater pressure up to 10 bar in 100-meter condition and also done some pressure test to verify the vehicle design is safe or unsafe.
In our case, we are using an Acrylic material to fabricate based on using CNC machine or laser cutting machine etc.
- Cylinder - 160 diameter acrylic tube used to cut prescribed dimensions and to form 4 holes in an equal position and all so form threads on both ends of the tube.
- X-tube frame - 4 tubes cut equal size in as per dimensions
- End caps - Square blocks is machining to form end-caps in as per dimension.The factor of safety vehicle end-caps thickness will be in 2 times of vehicle cylinder thickness.
- Motor base - Round blocks are machining to form as per dimensions.
Step 5: ASSEMBLY
NOTE: If you can use 3D printing to the fabrication process and you don't need to the assembly process.
In our case, we are using chloroform or anabond to fix the vehicle parts such as the cylinder, X-tube frame, motor base.
The Bldc motor is fixed in motors base and attached 4 propellers with the help of propeller adapter.
The vehicle will be sealed in underwater condition using emseal to seal the motor wire parts.
The O-ring is fixed to both end-caps to provide additional sealant and both end caps are the open and close type.
The end cap parts to provided Teflon tape to avoid the leakage and then to completely sealed the entire vehicle.
You have to ensure vehicle is completely sealed to withstand the underwater pressure
Step 6: CONTROLLER CONNECTION
The control parts represent four motors and two motors rotate in clockwise and another two motors rotate counterclockwise direction. Motors are controlled by the Electronic Speed Controllers (ESCs).
ESC is connected to Flight controller and to move the vehicle with the help of 2.4ghz signal transmitter and receiver
NOTE: If you have added some other components also such as camera, LED light, underwater pressure sensor, sonar etc. Mass distribution very important
NOTE: Use Ardupilot Software to install the program file in flight controller. ESC calibration is also important.
Step 7: PROTOTYPE
FACTORS CONSIDERED IN UNDERWATER
- Vehicle stability
- Added mass due to the inertia of the surrounding fluid etc.
NOTE: Signal transmission is a major problem in the underwater condition
- We are planning to use wireless signal transmission but the vehicle is found to be stable and wireless control is working for about 0.5 or 1 m from the surface of the water. so we are planned to develop floating theater system used in the underwater condition.
- The tether system will be the float and the cable will connect to the one end in the vehicle and another end is connected to tether system and this system cable tether length is controlled by using motor based on depth range.
NOTE: This is our first prototype in HYBRID DRONE
I just added my initial testing videos (:_'_:).
Air Ocean team