Submarine

[uaefame]

Hello everyone,

I am interested in building a robot that can navigate under water using a PC or any other method.

Q1> what is the best type of navigation?
Note: The submarine (robot) will be tested in the pool first.

Q2> what is the best type of motor for underwater?
Note: Right now the test will be done in pool 1.5m deep maybe in near it will be tested in deep water 30m to 50m. I am building a model first that can handle maybe upto 3m. In future i might scale the robot to handle more pressure.

Best regards,
Hesham

 

[Mercur]

Your best bet for a motor would probably be, at least for testing the thing; a regualr motor similar to those in RC cars with grease around the axel and body gap to prevent leakage and the remainder sealed in the submarine body.
For navigation; how much are you going to spend ?
A cmos camera in the nose and thena simple remote control either as a PC program or a Remote.

 

[dknguyen]

Motor- WHat will decide this is what propeller and drivetrain you can get and the motor that will fit with it, rather than the motor type
https://www.crustcrawler.com/

Is this remote control? Or autonomous? And I assume it's freshwater (RF does't work very well in salt water).

Camera if it's remote control.

SONAR for obstacle avoidance is by far the best method. For navigation, simple inertial navigation with gyros and accelerometers, but don't expect it to be very accurate without getting very expensive. I'd probably just try a compass and depth sensor over a gyro and accelerometer first since they are much cheaper and simpler.

Submarines tend to have a very hard time navigating. Real ones have maps of the sea floor and use sonar to make an image and then compare it with their maps. THey also use very expensive and accurate inertial navigation that works for months at a time, but even then they have to surface and use GPS to recorrect their position (or map the sea floor).

 

[Menticol]

I'm not a robot builder, but you have to thing about the variable ballast, to control the depth. I think you need somekind of air storage tank, pump, valves... controlled by your method od choice (RF, etc)

 

[uaefame]

Right now, I will focus in sensor.

I want the robot to be autonomous. I was thinking about using GPS to control robot.

Is it a good idea? Is it difficuilt to build?

Thanks in advance

 

[Nigel Goodwin]

How will GPS work under water?.

 

[uaefame]

Hello,

How will GPS work under water?.

Through a google search and reading more about GPS, It appear that GPS can only be used for fresh water (3ft) and salty water (1ft) because of conductivity and reflection. Therefore, I think GPS is not a good idea.

I will stay with sonor for the time being... I am still thinking of a way to define the location of the submarine under water.

Note: I will test the submarine first in a pool or tank.

 

[arrie]

You'll have your hands full with this one.

As mentioned, sonar will be your best bet to make it autonomous, but good luck with programming that.
What would you like to do with a sub anyway?
Or are you just looking for a toy?

 

[Mercur]

What would you like to do with a sub anyway?
Or are you just looking for a toy?

If cost is not an issue I belive there are toy submarines you can buy fairly cheaply form toy stores; they only go straight and are not autonomus etc but it may help give you some ideas for the construction requirements.

 

[dknguyen]

THe idea is to use INS and surface every so often to recalibrate your position and reset the accumulated INS error. But GPS is only accurate to 10m or so and if the operating time is short enough INS alone might be accurate enough. An INS system requires expensive sensors and even serious processing power and programming. Building one is expensive and risky (since it could not work and you could end up wasting your money). THe cheapest ones are about $1500 but these ones only keep track of orientation and the ones that keep track of actual position are $5k+. YOu don't really even need the orientation stuff since submarines have slow acceleration, angular velocities, and angular accelerations that you could probably leave out the gyros and get away with just an accelerometer for orientation sensing.

Overall, I believe tHe cheapest way is to use an accelerometer and 3-axis compass to maintain your direction and resurface every so often and use GPS to figure out how far you travelled. About ~$150 worth of sensors with some programming that a simple uC should be able to handle.

 

[littlejohn0]

hi

if you want a good starting point for your ROV.
you can't do better than to go to
**broken link removed**
for an off the shelf easy to build ROV using plumbing fittings and sump pumps
he gives full biuld and program instructions for a rov with cctv-compass-depth-temp-and a lot more.

for for the program control board and motor drive go to
Robokits World, Easy to Use, Versatile Robotics Kits...
the most complete pre built clip together components i have found to date and cheap too

hope this helps
littlejohno¼