PRODUCT DEVELOPMENT MOD007114

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Deep Nanavati : 2045651   Jay Kher: 2060438   Ehtisham Afsal:2129564   Romil Modi : 2055626             

                        Malewar Tanish:2130193     Jorge Locker: 2012469  

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The brief we have been given is to redesign the SPIDRJet drone made by BAE Systems. The brief states we must reduce the weight of the chassis by 20% by design or material change. Overall weight should be less than 2kg and to redesign the leg to increase the reach up to 300mm while keeping the same electro-mechanical design of 3 joints powered by 3 servo motors.

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Market Research

For our market research we decided to focus on other quadrupled drones available on the market. 

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We found that most bodies were made of ABS or carbon fibre composites while the legs were made from ductile aluminium. 

We also found that the leg designs we’re not solid parts, they were framework to form a kind of skeleton frame instead reducing the weight of them. We also noted how these drones have rubber feet on the bottom.

Product Design Specification

Current Body Design

This is the current design of the drone we was given. It weights 0.548kg and is made from ABS Plastic

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Body Concept Design 1

• For this design we looked at the images of the complete drone to try and find where we can remove parts or cut down and we focused on this part here. 

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• On the original design this was a solid block with a hole in each side but we couldn't find a purpose for the hole, so we removed the block. 

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• Added a cross support instead and a bar across the top for the hole in case it had a purpose we couldn't find. 

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We also decided to change the material to polycarbonate as it has a similar strength to ABS while being more lightweight.

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Weight is 0.42 Kg

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Body Concept Design 2

Weight = 0.449 Kg

Spacious body, to fit electronics

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Dividers for electronic circuits, disable circuits to move inside the body.

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Material = Polypropylene

Body Concept Design 3

• We reduced the thickness of the block marked in this picture to get a bit more space and to reduce the weight.

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• Removed the cross-section design on the base of the body to reduce weight.

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• Material used is polypropylene

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• Weight of this body design is 0.450 kg

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Current Leg Design

This is the current design for the leg. It is made from ABS Plastic and weighs 0.169kg and extends to 238mm.

Leg Concept Design 1

• For this design, we kept changed the material to polypropylene and made the joints thicker to strengthen them and added steel rods to reduce the possibility of breaking under stress.

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• We also added rubber bearings around the steel rods to absorb some of the force on the joints.

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• We also added a rubber foot to add grip and absorb some of the force applied. It has a reach of 293mm and weighs 0.212Kg

Leg Concept Design 2

• The legs have been changed in a way to perform in different climate conditions and in different surface places.
• We have change the material to polypropylene for reducing weight and to make structure perform in all condition.
• For the structure we have change in a fine bridge structure which can help us to reduce weight and make it stronger and can perform in any condition.
• This form of bridge structure we have in the middle section which have the most force to work with..
• The weight of the legs will become 0.113kg

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Leg Concept Design 3

• For the drone's legs, we switched to polypropylene.

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• To reduce weight, we changed the design by designing two rods instead of a solid bar and we constructed a thin polypropylene wall to give more strength.

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• The reason we did not choose this leg design is that putting more stress on the legs can easily break the rods

Final Design

Overall weight is 1.897 Kg

Materials we used are polypropylene, silicone rubber and steel

Design Review

To pick what concepts we used for the final design, we built full assemblies for them and ran the same simulations on them and analysed the results to see what worked best, what we liked about each design and what would work best for our final design.

Final Design Evaluation

Overall, we like the design we ended up with, if we were to do this again, we would like to test out other materials what wouldn’t be restricted by an overall weight of 2Kg as that restricted us to mainly plastics. When designing the drone, we kept in mind the manufacturability and kept to parts that could be 3D printed.  As a group we focused more on the leg designs than the body and after we feel we should have spent more time working on the body to see if we could have made it better.

Finite Element Analysis of Leg

Simulation of Safety Factor under 30N load

Simulation of Von Mises Stress under 30N load

Finite Element Analysis of Complete Assembly

Simulation of Von Mises stress under 30N load spread over the four legs

Simulation showing safety factor under 30N load spread over the four legs

Reviewing Ideas

• On the initial stage of redesigning body and legs of drone, we just went through ideas like Circle designed body or square.

• This designs were major failure as they get force on any side of the body out body got bent inside.

Failures

As on redesigning we faced some of the failures in the designs such as in above image we observed at the deformation of the structure when applied force on the body of drone.

Failure could be due to :

• Design
• Inappropriate material
• Manufacturing process

In our case, in one of our design, failure was because of the design by which body deformed. There was less connectivity between base and pillars.

Value Analysis

Recyclability

• When we were looking at materials, we kept in mind of recyclability of them as we wanted to keep the drone materials as environmentally friendly as possible.
• Polypropylene is 100 % recyclable- we would aim to buy recycled polypropylene
• Silicone rubber isn’t as recyclable but up to 70% of it can be reused after the recycling process
• Steel is 100% recyclable – we would aim to buy recycled steel

Conclusion

We feel as a group we have met the brief we were given and have produced a product that would hold up to the task.