MECHANICAL DESIGN

Inventor Drawings


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2233

The above 3D drawings were made in Autodesk Inventor 2015. Our entire fabrication was based on the dimensions planned out in the above drawing. We had to be very meticulous in planning, and thereafter had to be even more meticulous in fabrication so that the pieces would align well and would be assembled with ease.

Design Explanation


 

1L

The above design was conceived due to how large our water containers were. As such, the size of the overall vessel had to compensate for this and hence resulted in a rather large assembly. The PVC pipe base network was designed in a streamline manner so as to reduce as much drag as possible when moving. Though the main feature of the vessel is not movement, we aimed to reduce the amount of work the propeller motors had to put in as much as possible.

Our electronics box was mounted at the top of the entire vessel as we aimed to keep the electronics as far away from the water level as possible. Another reason for this is for the GPS Shield’s antenna to have an unobstructed line of sight to the open sky to allow for it to pick up a strong signal. Furthermore, we also had to house the Bluetooth module as far away from the water level as the waves in the water could interfere with the signals transmitted and received by the module.

We used Styrofroam to keep the vessel afloat due to its very high buoyancy, which counteracts Imp Bot’s low buoyancy. Further proof can be found in the Analysis section.

We 3D printed pipe brackets to join the aluminium frame with the pipe base.

2

We used aluminium L brackets as the entire vessel bore a lot of dynamic load as the water containers could either be empty or full. Hence, the aluminium brackets ensured that all our motors were mounted properly and that it could bear the load without breaking.

We made a triangular shaped aluminium frame for the propellers to be mounted below the pipes. As the motors would be exerting a lot of torque, the aluminium frame would be able to sustain this without bending or breaking.

The actual water collection action is carried out by 2 motors. The first motor, for example, Container Motor A will rotate the spool such that Water Container A is lowered into the water. The container is by default open as it has a lever holding the acrylic circle open. Upon reaching the desired length, in this case, 1 metre, Bicycle Brake Servo Motor A will start turning from 0 degrees to 180 degrees, then back. It repeats this motion 3-4 times to ensure that the lever is pulled upwards and that the container’s acrylic piece is shut and water is trapped inside the container. Container Motor A then rotates in the opposite direction from previously so as to coil the nylon rope on the spool and reel Water Container A up. Upon reaching its original position, Container Motor A stops and the water collection action is complete.

The same principle applies to Water Container B, except it gets lowered to 2 metres instead of 1 metre underwater.

3

To abide by a convention, by facing the stern of the vessel, all motors on the left hand side were labelled A and all the motors on the right hand side were labelled B. By sticking to this standard, we completely avoided mix-ups in motor referencing along the way.

 

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