Rov for Pools - Balance


I need to build an rov that is very balanced, easy to drive and maneuverable. It can only have three motors. It will drive in swimming pools. Here are my questions:

  1. How does the height, width, and length of an rov affect it? I think the height affects the distance between the center of gravity and buoyancy but am not sure how to apply this to the actual robot.

  2. Please link any helpful resources that can make an rov very balanced.

  3. The rov will participate in different challenges. One is to pick up objects and one is to maneuver through hoops as fast as possible. How can the ballast/flotation be changed for each challenge?

Another question you may want to add…How will repeated exposure to a clorinated environment effect durability of the seals and other components?

Sounds like you are doing a MATE ROV competition. Read ROV Manual and Underwater Robotics

Short answers:

  1. Just how you think they would. For a statically stable ROV you want the COB inline and above the COG. If you want a dynamically stable ROV, then stick them together. I leave it to you to figure out the differences between static and dynamic stability.
  2. The books above are your best bets for learning about ROVs, also check out MATE’s website, but from question 3, sounds like you have already done that. And don’t make the mistake that someone will do your homework for you, lol, that never ends well. I’ve seen vehicles disintegrate because teams didn’t do their homework.
  3. Why do you think you need to change ballast/flotation to accomplish these two tasks?

When you have some designs, post them and folks will chat, but you need something to start with, otherwise, you aren’t going to get many responses.

…and chlorine over a short period of time is ok, but it matters in the long run, so there’s that.

Best of luck,


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G’day namanagarwalat,

Welcome to the forum. As you might have realised, Trident has three thrusters so you are in the right place and you have already gained the attention of very knowledgeable people.

From a design point of view, make sure you understand the range of operational requirements imposed by the competition including the environment itself plus any factors or limits relating to the various tasks your ROV will be required to perform. Recovering a small and stable neutrally buoyant object with good connection points in shallow water with good lighting/visibility, no obstructions and zero current is a relatively straight forward process…vary any of these parameters and your task might require more careful thought and a more capable design.

I would start with the smallest ROV that you can create with the available materials and components and then increase its dimensions only when needed to improve its ability to perform a high ranking task.

Take examples from common underwater vehicles and devices…torpedos perform a particular task very well whilst lifting bags perform another task very well. Their respective designs will provide you with some clues to help your own design take shape.