APPLICATIONS IMPLICATIONS

Overview

This week requires us to propose a final project masterpiece, focusing on previous projects and the plan to realisation. The idea as I have drawn it out has never been done in the same manner before. Many have achieved the modular parts of the project or designed according to similar ergonomical and biomedical design goals. I will used each of those projects as references when constructing the modular parts of the smart walker. Therefore, I decided to break down this section by processes of fabrication to achieve better flow in the explanation. The next section will break down the parts involved and the processes required to fabricate each of them. More info regarding how parts were actually realised is available on the

Parts and Processes

As mentioned, the final project design is modular with some essential components and various additional non-essential components. In this sections I will highlight the processes and materials required for each component. Below is the modular map of the final project to give a better idea.

Essential components

Part	Processes	Materials
Skeleton	Metal bending and cutting, 3D printing	Aluminum rods, PLA filament
Wheels	FDA/ SLA 3D printing	PLA, flexible filament, flexible resin
Oxygen tank holder	Laser-cutting	5mm Acrylic
Handles	Molding and Casting	Wax, MoldStar30 silicon, dye
Pulse and Oximetry loop	Electronic design/production, Input devices	PCB with Microchip, Pulse/Oximetry sensor

Non-essential components

Part	Processes	Materials
Outer body	CNC	Foam and composite coating
Distance tracker	FDA/ SLA 3D printing	PLA, flexible filament, flexible resin
Fall prevention system	Laser-cutting	5mm Acrylic
LED lights	Molding and Casting	Wax, MoldStar30 silicon, dye
Phone interface	Electronic design/production, Networking and intefacing	Bluetooth module, Phone
Oxygen-valve control	Electronic design/production, Output devices	Digital solonoid-valve
Fall alert system	Electronic design/production, Output devices	Alarm, PCB
Screen	Electronic design/production, Output devices, intefaces	PCB with Microchip, Screen

3D printing

The first compnoents to be 3D printed are the wheels. I went with a non-pneumatic tire design, to allow for better shock absorptiona nd avoid using air-pumped tires. Bridgestones wonderfully executed is one of the many examples of such tires. Other companies such as and have also had a go at this novel concept.

Higher flexibility in the front wheels will achieved both by fabricating using FDM flexible material due it's higher flexibility as well as a less rigid pattern within the wheels. The rear wheels will be fabricated usin SLA flexible resin. Both wheels will have their inner piece printed using high-strenght PLA filament.

The other 3D printed parts, are going to be joints between the aluminum hollow rods. These will also be printed out of high strength material, possibly PC. Several examples have been done using this approach, such as this pictured on the right.

Laser-cutting

The only laser-cut component is the oxygen tank holder, which due to mainly aesthetic reasons, I will be fabricating out of acrylic. For a stronger body, I chose 5mm thick acrylic. I found an example of a wine bottle case that used a very interesting approach using wood kerfing. So I decided to use a similar approach that has been achieved but using acrylic instead of wood.

CNC

Although I was thinking about creating the full chassis using the CNC. I changed my approach to using the aluminum rods shaping the outer body using CNC'd foam. The foam will then have composite material sheet set onto the CNC'd foam. This will give it a nice shape using the foam and the mechanical properties using the composite material. There have been many examples in fabacademy of this workflow such as Fabio Ibarra

Tormach 1100 CNC was used to mill the aluminum mold for lead casting part of the multi-dimensional logo.

Molding and Casting

For the handles of the walker, I was inspired by the grip on this walking cane shown on the right. The grip was designed in an ergonomical point of view to make it easier for arthritis patients to hold it. 49.6 percent of people over 65 years have been diagnosed with arthritis. Therefore, I believe it is integral to have this design feature within the handle grips. I will be using the SRM-20 to mill the wax mold, then cast Moldstar30 for the grip itself.

Another molding and casting component that was done during molding and casting week is the multi-dimensional logo. This was mainly done for the weekly assignment and doesn't add any function to the walker, other than making it look cool. The component consists of several molding and casting stages, integrating two colours of smoothCast resin, clear polysterene resing as well as cast lead.

Electronics

The electronic's sections brings together several processes such as electronic design and production, input devices, output devices, networking and interfaces. More than one electronic component will be involved in different parts of the walker's body.

The first component is the main microchip board controlling all the electronic functions of the smart walker. I have designed this component during input week. It is an extremely modular microcontroller, based on the arduino design that allows for a large number of outputs and inputs to be connected. I called it the Byrduino.

The next boards I will have to design and fabricate are the output and input shields. I plan on stacking them over the Byrduino with clear sockets for the input and output wires to avoid confusion and make the connection more fool-proof. An example of such an approach is Daniele's multi-core

Other smaller boards were designed for networking functionality such as a WiFi and bluetooth board. They, as well can stack above the main board.

Initial Bill of Materials

The following bill of materials is an approximate and the complete accurate list will be available, including the exact quantities, at completion of the project, as some parts might change or others added.

Material	Cost(USD)
Aluminum and Fiber tubing	100
PLA Filament	40
Flexible Filament	10
Acrylic	10
Silicone	10
Wax Blocks	10
Screws and Nuts	~5
PCB material	10
Bluetooth Module	15
Accelorometer	10
Oximeter	25
Rotary Encoder	3
Total	250

Evaluations

To evaluate the success of this project, especially as a masterpiece of all the skills I've learned and mastered throughout this course, A set of criteria must be specified. Each criterion, evaluates a certain week and success in all criteria means success of the product as well as proof of proficiency in each skill.

Skill	Criterion evaluation
CAD	Design a parametric model, where possible, for renders, printing, cutting and millng.
3D printing	Successfully print parts making use of slicer settings and model structure to achieve the desired aesthetic and mechanical properties.
Laser-cutting	Successfully laser-cut a part. Use kerf offsets to achieve a press-fit between components and kerf bending to tackle curves.
CNC	Use CNC milling with 3-axis cutting to tackle larger parts with topographic surfaces.
Electronic Design	Design at least 3 boards to serve different modular purposes within the product.
Electronic Production	Produce the designed boards using coating or flexible PCBs if needed.
Molding and Casting	Use multi-stage molding and casting techniques, including 3-axis wax mold milling, to achieve properties that would otherwise be unachievable.
Output devices	Employ atleast one indicative output device.
Input devices	Employ atleast two input devices, one for data and the other for functional purposes
Networking	Communicate wirelessly to send data to the user via bluetooth, wifi or radio freq.
Interfaces	Display input data and feedback through a mobile interface
Web design	Document in detail all aspects and modules involved in the fabrication of the final product.
Digital design	Design a poster presenting the product in a stylish manner.

There are no files for download this week