NOTE: Images can be expanded by clicking on them

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XE521 – engineering design module introduction

This module is a group project which involves two tasks: one was to design a SUBCAM (an underwater camera with the capability to move) and the other is a robot wars project. This is where, as a group, we were to design and build a robot to battle against others.

SUBCAM project

pin-up work

For this model our group had to present a pin up. This is a collection of work and a proposal for our idea. The pin up would present our idea to other students and the lecturer of which we would be marked for.

Justification of subsystem:

Decision matrix:

Poster work

Mathematical models/suitability:

Above is some mathematical models and suitability work. Part of this was used for the pin-up.

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Robot war project

For this project we had to work in groups to produce a battle bot to fight against others. My role for my group was to come up with a concept and make a CAD drawing of this concept. One task for this part of the model was to present it as a pin up much like the SUBCAM above.

Concept work:

Below is a collection of photos of quick drawings I made. the main concept was to have a robot that was flat enough so that it could slide under the opposing robots. Once under the opposing robot, pistons could activate and launch the opponent into the air. I also came up with the idea of giving the robot the ability to extend and retract itself. This would allow it to be more defensive and move faster. I also thought of giving it the ability to arch itself. This could also help its attack power. For example, if the robot arches when it is under another robot, it could launch the opposing robot further in the air, thus doing more damage and hitting the ground faster.

CAD concept design:

For my CAD models I decided to make the concept that was split into sections instead of the one with one massive piston on top. I did this because I felt it was a better design and could cover more in Solidworks. I started by making the individual components and then removing parts so that the assembled robot would be under the weight limit. I also made 2 assemblies, a 3 segment short version and a 4 segment version. Below are photos of the assembly models I produced. I also can up with some estimated weights and extension and retraction lengths:

Here is a download zip file for the components and assembly of the 4 segment version with a technical drawing of the assembly:

Click Here: Assembly of concept with technical drawing

Here is a download zip file for the components and assembly of the 3 segment short version: Click Here: Short assembly for concept

Technical drawing for concept

Here is the technical drawing that I made for the 4-segment version of the concept:

A download above for the 4-segment version contains this technical drawing

Mathematical models for robot concept

Here are some mathematical models of if the machine were to launch another robot into the air at different velocities:

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CAD assembly and technical drawing aid

For the making of the robot, CAD models for each component needed to be made with a technical drawing. This was so that the assembly could be approved for the material to be cut. For one of the subsystems of the robot, I was asked by another member of the group to help them make some adjustments and complete the assembly. Once this was done, I then helped them with the technical drawing before it was to be sent off for approval.

To start I had to check the components were the correct size so that the screw holes would align. Once all the components were of the correct size, I was able to use mates in Solidworks to assemble the pieces in the correct way. To begin with I had assembled the sub system incorrectly, this was due to a communication error. However, when speaking the the team member further, I was able to correct the mistakes and place the components in the correct places and make them of the correct size. Below is a photo of the incorrect assembly:

For this assembly I had placed the silver brackets in the wrong place. They were meant to be placed where the MDF strip is on the right of the photo. Also the MDF strip was meant to go in front of the batteries, not behind it. Below is some photos of the correct assembly:

 

Technical drawing:

To go along with the CAD assembly, I was asked to help the group member make a technical drawing for this assembly so that it could be approved by the lecturer to be cut and built. For this, the technical drawing had to show all views including an isometric view. This was so that the people reviewing the drawing and approving it would be able to see the assembly properly. Below is the technical drawing that I created and then passed over to the other group member to add his parts. This technical drawing was approved by the lecturer and was built into the robot.

Here is a Solidworks download for the full battery tray assembly and the technical drawing that was built:

Click Here: Full battery tray with technical drawing

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Final robot and outcome of project

Below are some photos of the final built robot for our group:

For this module I mainly helped with the CAD and the technical drawings. The design of the robot was not using the concepts that I produced but a concept that was made by another group member. We decided that that design would be better as its weapon would be ore effective and also my concept would have been very expensive. Ultimately, the concept that we were aiming for was not the same as the final design. This was mainly due to time issues. A features that stuck though was the battery tray assembly that I helped get ready for approval (it can be seen in the centre for the robot under the copper plates). Originally the casing was meant to be made of steel, this would have been made also using CAD. I was to help make the CAD models and technical drawings for approval as agreed. However, this never happened due to lack of time. Instead of a steel casing a plywood casting was made instead by the other group members.

Another part that did not occur was the weapon. Originally there was meant to be a rotary saw on the end. Due to improper communication I and others in the group were not aware that this had been altered to be a hammer instead. This lead to delays in the build and ultimately lead to no weapon being constructed at all because lack of time.

Testing and battle

When it came to the testing and the battle the final design had very little movement. It was only really capable of turning in circles and only with one wheel at a time. There was a issue where one of the motors in the system was spinning in the wrong direction but even when we fixed this problem (by unscrewing and flipping the connection points) the robot was still not functioning as intended.

If we were to do this module again I believe I should focus more on the building of the robot. Although the CAD was good and helpful, I noticed that there were better solutions to holding the batteries. For example, I noticed that other groups had used zip tires or had hot glued the batteries to the base of the robot. Next time I would use a less time consuming solution so that more time could be given to the casing and the weapon. I would also maybe implement a plan and a time scale so that different parts could be given time and actually be completed. I would also improve my communication with the group so that communication errors are less likely.

Below is a video of the robot in the battle area:

 

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References

References for SUBCAM project:

Izadi-Zamanabadi, R., & Blanke, M. (1998). Ship Propulsion System as a Benchmark for Fault-Tolerant Control.

Information on propulsion systems from Aalborg university Denmark. https://vbn.aau.dk/

mecaflux. (2021). Hydrodynamics, general. Available from: https://www.mecaflux.com/en/hydrodynamique.htm [Accessed 17th February 2022]

 

Information on propellers from Dave Gerr’s propeller handbook

Information on dynamic model for thrust generation of marine propellers written by Mogens Blanke, Karl-Petter Lindegaard and Thor I. Fossen. https://orbit.dtu.dk/en/publications/dynamic-model-for-thrust-generation-of-marine-propellers

Thrust equation for propellers from Embry-riddle aeronautical university. https://commons.erau.edu/

https://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node86.html

https://www.gaelforcemarine.co.uk/

https://en.wikipedia.org/wiki/Buoyancy