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Make your own Aqua Polo Robot

Updated on May 7, 2013

Aqua Polo Robot

Project Level
Easy (Begginer's Level)
Time to make
1 hour (estimated)
Estimated Cost
Low (~20$)
Robot Control

Aqua Polo Robot

Today, i suddenly remembered of my old store, and came out with a project untouched since past many months. I suddenly realized why not share this abandoned cool stuff with you.

'Aqua Polo bot' has been the very first Robot made by me. I with my 3 other friends made this Robot, 2 years ago; and presented it at an inter-collage Competition organised in our Collage Campus.

In this Competition various Participating teams demonstrated their bots in an S- Shaped water track Starting from one end to reach the other, while at the same time Capturing the balls floating over water in robo arm to place at 3 definite goals set in the pool. It was really a great fun.

"This is very simple and cost effective project, and you will enjoy making and playing it."

Various Participant teams had their own models with basic concept being the same. Some of 'em had structures of ship made by GI sheets, while various others had fixed wheels and motors over a plain wooden plank.

An other impressive concept was, just fixing the motor wheels to a thick thermocol polystyrene sheet supported by a thin cement sheet, to provide weight for balance. We would have never imagined the concept if not seen that. Well but that roughly made device was good enough to work. That day i realized resources are never the limitations, substitutes are limitless.

"This Project contains a Boat model and a Control Box, which will be your hand gadget(remote control), to control the movement of Robot. The control box signal reaches the boat via a 10-Led wire."

Another big thing folks, when our seniors first time introduced us to "Robotics Workshop", what they told us was:-

"It's easy just join the parts, that's not engineering. A mechanic's job is to assemble the parts, but an engineer's job is to 'innovate'. So, rather than obtaining the desserts from market just serving and enjoying it, better learn to prepare your own dish, than serve it. And than when you eat it, you'll gain another bonus special feeling apart from taste itself.

How to make ?

We'll make our project in 3 basic steps

#1 Design of the bot structure.

#2 Design of control Circuit

#3 Join the two objects.

Next will be, take your device to any water pool. Provide Power Supply and Have fun. :)

Click thumbnail to view full-size

Boat Structure Design

Materials Required:

  1. GI Sheets(49cmX49cm) :- Galvanised Iron sheets, generally k/as GI sheets are light, strong, corrosion resistant Stainless steel sheets. They are used to make the basic physical structure of the boat, and can be easily found at any hardware store.
  2. 100rpm-24Volt External gear DC motors (4 nos.):- These are actually responsible for the movement of your bot. Two motors Control the side-wheels, 1 for power booster and 1 for Rotating hand.
  3. 15-30rpm-24Volt DC high torque Motor(1 nos.):- This high torque motor Controls the Up and Down Movement of Robot hand.
  4. Screw, Washers, Nuts and Bolts, and Electrical Tape.
  5. M-seal:- Since, your Robot needs to work under water; It must be highly shielded from all corners and side. we Don't need to weld at every position. At many Points M-seal comes out of great use. We should apply it to cover the holes we created to insert the screw, nails or wire.

Note:- Excess use of M-seal may make the weight of your boat extra heavy.


Iron Cutter:- This would be needed to cut off the Iron sheet. Though it's an important instrument to make our project, but it's not a part of our design. So, i may suggest that despite of buying it, you can even ask your retailer to cut the sheet and provide you in a form you need it.

Welding:- This is done to join the GI sheet, as glue won't works here. For Welding you can take your structure to any hardware store.

Very Important

While you design your boat, it is really very important to keep these points in consideration.

  • The Boat should be designed with proper measures so that Center of gravity of your boat must coincide with the Centroid of boat. Otherwise, the boat may not be able to balance itself under water. And if you increase its speed while working, the boat may bend or even turn upside down.
  • Be sure to properly seal off, any holes made(specially in bottom portions) of your boat.

Even while applying M-seal, be sure that the mass shouldn't exceed in excess at one corner, causing the boat to bend.

How to make your Boat ?

Step#1 Cut out a 38cmX38cm piece out of GI Sheet. Make a square of side 20cmX20cm on it, leaving a margin of 9cm on each side (that's a good height for side walls, to avoid water entering it when you run at high speed.)

Step#2 Cut along the Red lines marked with a cross (X). Fold the Sheets along each side of square marked a,b,c and d, to form the side walls. (Refer Fig. Sheet 1)

Step#3 Now take another rectangular G1 sheet of side 15cm X 12cm. Cut the cross marked lines and fold along sides 'x' and 'y'.(Refer Fig. Sheet 2)

Step#4 Next Comes the welding turn. Weld the the obtained contains at all sides, and join the two containers to obtain the Structure of ship as picturised below.

At the Corners of welds 'you may also apply M-seal, if needed.

Aqua polo bot Structure

Wheels of boat

Use of wheel

Wheels attached to the two sides of boat are connected with motor armature. Their basic task is to accelerate or decelerate the boat, and to turn it's direction.

Each motor is connected to a rocker switch, which can either make motor to move clockwise or anticlockwise, to provide the boat forward or backward acceleration. They have turbine kind of structure to push water forward or backward as they rotate

How to make the wheel?

Well, wheel can be made in any possible ways of your imagination, via spoons, via GI sheets or whatever way you can imagine best. Or even in form of fins, considering Bernnoulie's Principle. Well, not going into it's details lets get to how i made my turbine

The way i used :-


  • Four plastic scales (15 cm)
  • Feviquick. (or any other glue which can join plastics)
  • Electrical tape
  • Four 2.5cmX8 cm strips of GI sheet.
  • Four plastic caps (say of a soft drink bottle.)

Take the two plastic scales of 15 cm, rite at half length, i.e. 7.5 cm; cut half of the width, leaving a small portion, as shown in picture below. Do the same with another scale. Insert the two scale in each other to form a cross, nicely stick them.

Now, Cut out the small equidistant width(2.5 inch) of wall of plastic cap and insert the scales in it. Fold the GI sheet in shape of L, and stick the two L's at any two vertically opposite angles of the Cross, to provide it the strength. Cover it with Electrical tape, or leave if you prefer transparent structure. Your turbine wheel is ready to use.

Now you'll have to insert the armature of your motor inside the cap and fill it with M-seal, so that armature sticks to it.

Finally, set the wheels an at two sides of boat, joined with the motors placed in it.

Remember:- Always place the objects inside the boat in a proper symmetry, such that the Centroid of structure always coincides with the center of Gravity of the boat.

You will have to drill the holes inside the boat, to give an exit to motor armature, and after all your fixings never forget to seal the holes properly to avoid entry of water inside the boat.

Speed Booster Mechanism
Speed Booster Mechanism

Robo Arm Design

Now that we are ready with our basic boat structure we need to design our Robo arm, to pick up the ball.

Again, the very famous and one among most loved word in Hindi - 'Jugaad', this term means substitute or alternate searched, creative method to do something.

You can have your own ways to make out your Robo hand. Among about 30 participating teams in our game None of the two had xactly similar ideas.

Here i'll share how my group arranged to make the Robo arm.

Needs for Robo arm

All we need is a hand which can be rotated in any direction, as well as moved up and down to capture ball, and a bucket to hold the ball, People generally use a plastic Rod for hand and a Steel Stainer, or half cut hollow cricket ball attached to it to hold the small tennis ball. Motors are used to provide movements to arm.

My Story:

What we used?..... Hmph, Pardon me for that - but 'yes', we used the flush ball. We were just planning, trying out with various possible ideas, only till one of our friend next day brought up the flush ball thing to us. At first we were shocked, but he explained, it remains in water tank, is clean and good to use, and moreover he has even cleaned it better.

Finally "Yes", we thought- Well, he is even right at his point. After all it was a well built, with proper rotation mechanism, ready to use thing.

Just Cutting out the upper half edge of the ball, our hemispherical bucket was ready to use.

We attached the two motors as shown in figure to provide the movements to the arm. High torque motor is used to provide the up and down movement to the arm, so that it can bear even the heavy load of it's prey "the ball or etc.".

What is a High Torque Motor?

Important point to mention is, as the torque value of motor increases, it becomes capable to support more weight, while at the same time it's rpm (rotation per minutes) value reduces, i.e. motor performs at low speed and vice-verse.

Speed boosters

And now the final attachment to our boat will go 'The speed boosters'. These are the optional wings attached at the back of our boat with a 100 rpm motor, which are used to accelerate the boat or to boost it's speed. You may use any bowl shaped object with holes in it. when it rotates it further causes the pressure difference at the back of boat causing it to be pushed forward further.

Control Circuit Design

So now, as we have already designed our boat, let's watch out how to make it's control circuit.

Offcourse, we cannot sit inside that 20X20 cm square box it's control the movement. So, we design a handheld remote control circuit joined to the boat via a long 10-lead wire.

Note:- wireless remote control mechanism can also be used, especially by digitisation, but we are not entering the complex stuff here.

The Control circuit is easy to design, and implement.

Materials required: -

  1. A PCB (Printed Circuit Board)
  2. Rocker Switches 5 nos.
  3. A DC jack - To provide input DC Supply
  4. Connecting wires. - To provide the connections with in the Circuit
  5. Soldering Equipments- Soldering iron rod, flux, and Soldering wire.

Rocker Switches -

These are switches with 3 positions +ve polarity 'On', -ve polarity 'On' and null 'Off'. The switch normally remains in null position, until and unless we push and hold the switch in any of the other positions. We here use the switch to provide alternate polarities to the motor at two diff. states, so that at one state motor armature rotates clockwise and thus the wheel, and in other state it rotates anticlockwise and so the wheel again.

Connections in a Rocker switch :-

In a Rocker switch the corner most pins are cross connected, so that left-top corner pin ahs the same polarity as right bottom corner pin (1 -> 6), and right top corner pin has same polarity as left bottom corner pin (2 -> 5). Input DC supply is provided at two opposite pins at middle(3 and 4) as shown in figure.

Finally, two pins of any end are connected to the motor.

working :-

Initially, when at rest(null) position, no power is supplied to motor, but as soon as we push and hold the pin it works as follows:

Suppose, pin 3 is +ve and 4 -ve, and pin 1 supplies current to motor terminal 'A', and pin 2 to terminal 'B',

Now as u toggle switch towards up (pin 1 & 2) side, it will make pin 1 +ve and pin 2 -ve. Thus, also pin 6 becomes +ve(cross connected with pin 1), and pin 5 gets -ve. Now, terminal 'A' of motor will gain +ve polarity, and terminal 'B' -ve. Thus, motor rotates clockwise.

In other case, u toggle switch down (pin 5 & 6) side, it will make pin 5 +ve and 6 -ve, and thus pin 1 -ve (cross-connected with pin 6), and pin 2 +ve( cross connected with pin 5). So, finally we have terminal A of motor at -ve polarity, and terminal B at +ve polarity. Thus, our motor now rotates anticlockwise.

So, here we got the trick to control the direction of motion of wheel, and thus the boat itself.

Now, let's move on' to design our chip.

Design of Control Circuit

Control circuit is designed on a single printed circuit board(PCB) of size 14cmX10cm(or as per your requirement).

Step#1. Six Rocker switches are inserted on board as per the convenience, to best handle the control of boat during its use.the switches are inserted from plane dielectric side of board, such that pins lie on the conducting side.

Step#2. Proper Connections are made to each rocker switch as per above demonstration.

Step#3 All the supply pins are bundled in common at the other end as per the polarity. (one bundle forms of +ve polarity and other of -ve polarity terminals).

Step#4 The two bundles are fed into the DC jack, which is than fixed at one end of the board.

Step#5 Now take the ten Lead wire and keep adding each lead to Pin 1 and Pin 2 of each Rocker switch.

Our Control Box is almost ready. Now, for safety and convenience of use we prefer next step

Step#6 Take a Plastic box of about the size of PCB, and place the entire circuit in it. Cut out the holes in box to avail switches and to give space to wire exit and DC jack, for power transfers. And fix the things Properly.

Circuit Design (RS-> Rocker Switches)

Watch out !!

Well you may notice friends, how roughly it is made, as it was my first circuit and a new experience i may forgive myself up to some extent.

But for now, i must say that in a circuit design it matters a lot how beautifully your connections are formed. Howsoever complex your project is-'It's preferred visual appeal is beauty over Complexity.'

How to join the wires:

For joining wire contacts with various pins on board or the other wire, Soldering technique is employed. If you are absolutely new to it than you may refer Video tutorials of "Soldering on PCB" on Youtube. For soldering you will basically need three things-

  • Soldering iron rod
  • Soldering wire - The wire melt is applied via heated iron rod at the points to join.
  • Flux - This is added to remove oxide from surface, if any. 'Coz Soldering wire does not sticks to the oxide surface.

Now after you have made your control circuit, box it out. Join the other ends of 10lead wire to corresponding motors and your 'Aqua Polo bot is ready to be used'

Take your Bot to pool, give it a supply through DC adapter inserting it into DC jack, Play with it. Have fun !! :)


I really apologise for such dirtful structure, but the thing is we really were more concerned of it's working than ideas applied over its aesthetic taste. Moreover, a long time storage has further worsened it's condition. And i wanted to present here the original made project.

But, You may may rather keep in consideration the beauty and attractiveness attribute as well, at the time you make yours project.

Furthermore, you may also vary it's size and structure parameters to obtain smaller, lighter or else other output pattern as per the way you needs and ideas.

You may also design wireless remote control later on by installing infrared sensor mechanism, and digital programming by installing microprocessor circuit. Or through your mobile phone, using DTMF technology.

Wishing you Goodluck to come out with your own Robot Very soon.

Thanks a lot for your patience with me, friends :)

Final Bot snaps at various angles

Click thumbnail to view full-size


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