Sustainable Product Design





FloodBud



The design of a flotation device to assist wheelchair users in reaching safety with their wheelchairs during flooding in India and Bangladesh


KEY SKILLS





Engineering Science



Problem Solving



Sustainable Design



Teamwork



Human Factors



OVERVIEW





BRIEF



As a group of 5, we were tasked to identify and solve a current sustainability issue occurring in the world. Several issues were identified, however the most prevalent was that wheelchair users are extremely vulnerable during floods and are 2-4 times more likely to sustain an injury during natural disasters.



DELIVERABLES



  • 80 Page Technical Report
  • 15 Minute Group Presentation


SOLUTION



The final design uses CO2 canisters with a two-stage inflation process, the product does not increase the width of the wheelchair, ensuring the user is able to exit doorways. Sustainability impacts were assessed using Ecoindicator tools, as well as technical calculations and simulation using Unity to prove the concept would work in practice.



SOFTWARE USED





Siemens NX11



Blender



Unity



SimaPro



DESIGN FEASIBILITY





Human buoyancy is quite complex, as it is dependent on the amount of body fat and lung capacity when submerged in water. As a result of this, humans have an ‘effective weight’ when fully submerged, which is around 5kg, regardless of their size. This was used as a basis to calculate the total volume of air required to float the user and the wheelchair. A 2-stage inflation process was chosen which allows the user to float 5% out of the water when inside their home, then 25% out the water when outside their home. Several locations for the buoyant forces were identified, however the most appropriate were chosen for the 2-stage inflation process.



UNITY SIMULATION







As well as conducting feasibility calculations by hand, simulation-based analysis was conducted in Unity. This was used to verify that the user would float above water, and the angle at which they sat in the water was appropriate. A standard water model and buoyancy script were utilised in this analysis as well as a wheelchair and human CAD model. Several dynamic properties were applied to the models including weight, drag and joints to achieve accurate results in the simulation. Also possible, is a method to increase the wave strength (Beaufort Factor scale) to identify what effect it would have on the model. To further analyse the product, a C# script was written which allows the centre of mass of the user to be changed to assess the effect on the stability. This is useful to be considered as users may have differing disabilities and muscle atrophies.



ERGONOMICS AND HUMAN FACTORS





Ergonomics and Anthropometrics



In order to understand how well the product fit the intended user range, an ergonomic analysis using NX human software was completed using anthropometric data for 5th, 50th and 95th percentile adults in India. It was identified from this that the majority of users fit comfortably with the flotation device in place and could reach neccesary areas of the wheelchair.



Human Factors



This investigated how the user would activate the product, and the system that should be in place for distribution of the flotation device. As shown from the storyboard, the user would require a carer to assist in activation of the 2 stages as well as getting the user to safety. The system requires aid charities who buy the product from manufacturers, transport to local areas and finally distribute to users in need of the device prior to flooding. After the flood, the charities reactive the CO2 cannisters and redistribute devices for the next use.



FINAL DESIGN AND RENDERS





Buoyant Locations



Initial Ideation



Unity Simulation



1st Stage Inflation



2nd Stage Inflation





Faheem Aziz (MEng, DIS)



Product Design Engineer