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Build Preparation

Table of Contents 1 Phase Planning 1.1 Build Preparation Shared Vision 2 End State Shared Vision 3 Imagine RIT Shared Vision 4 MSDI Business 5 MSDII Project Plan 6 MSDII Test Plan 7 Problem Tracking 7.1 Failure Modes 8 Engineering Fruition Plan 9 Updated Bill of Materials 10 Electrical Build 10.1 Schematics 10.2 Electrical Prototype 10.2.1 Tested Systems 10.2.2 Soldered Systems 10.2.3 Unsoldered Systems 11 Mechanical Build 11.1 Component Housing Redesign 11.1.1 Motivation 11.1.2 Associated Documents 11.2 Muscle Attachment Redesign 11.2.1 Motivation 11.2.2 Associated Documents 11.3 Lower Attachment Redesign 11.3.1 Motivation 12 Build Preparation Review

Phase Planning

Build Preparation Shared Vision

Our vision for week two is to finalize the design and begin building of the following components:

• Upper Plug
• Lower Plug
• Upper Base
• Component Housing
• Strap
• McKibben Muscle

The completion of these components will lead to assembly and integration of our subsystems from MSDI in phase 5.

Our team also plans to validate received components as well as the printed circuit board design.

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End State Shared Vision

Required Deliverables

The best case scenario is that we have a prototype of an untethered system with the gait monitoring system. If this is not completed with full functionality, then we will present a system with partial functionality. In this situation, explanations and proposed design changes will be provided. The worst case scenario will be presenting a final prototype with functioning pieces but not have a fully integrated system.

Bill of Materials

We will deliver a Bill of Materials (BOM) which lists all of the materials included in the final prototype.

Detailed documentation of design

We will have the current design along with changes made during the building and testing of MSD II. In addition to this, we will have recommended design changes for future models as well as tips to help with the build process.

Supporting test data and documentation

We will have test documentation supporting all of the engineering requirements. If we are unable to achieve full functionality, then we will test what is possible and provide documentation about the procedures that will be used to test the rest of the functionality.

User’s guide for operation

We will have a user’s guide for operation. This will include the following:

Application of the Active Ankle Foot Orthotic (AAFO)

Recharge and refill information

Washing information

How to retrieve data from the gait monitoring system

Basic trouble shooting

Showcase at Imagine RIT

Best Case Scenario: We will demonstrate our working prototype to the public using a team member as the volunteer. Specifically, we will have the volunteer walk on flat ground as well as on the stairs. This variation in terrain will help show the full functionality of our device. Throughout the day, two team members will present at the booth at all times and we will rotate between volunteers every two hours. Alongside the demo, we will display our team poster on our table which further explains the background of the project, design features, and testing and simulation results. Next to our poster, we will have a monitor that plays a video to further display prototype functionality as well as two air muscles for the public to see and touch. Lastly, our team will hand out project overview sheets which include a QR code to direct visitors to our EDGE site.

User Input

We will look for user feedback in, ideally, two ways. The first way will be to get input from students and faculty on the RIT campus. During this initial subject testing, our team will gain feedback on our qualitative engineering requirements, such as comfort, ease of application, and aesthetics. Following this testing, we plan to revisit the Physical Therapy Clinic at Nazareth College and speak to clients with Foot Drop. At the very least, we would like to have them try on the orthotic and get their feedback on overall design and wearibility.

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Imagine RIT Shared Vision

The following document displays the team's vision for Imagine RIT. Overall, it summarizes our team’s vision for Imagine RIT and presents different scenarios of readiness as well as our elevator speech.

Best Case Scenario:

We will demonstrate our working prototype to the public using a team member as the volunteer. Specifically, we will have the volunteer walk on flat ground as well as on the stairs. This variation in terrain will help show the full functionality of our device. Throughout the day, two team members will present at the booth at all times and we will rotate between volunteers every two hours. Alongside the demo, we will display our team poster on our table which further explains the background of the project, design features, and testing and simulation results. Next to our poster, we will have a computer that plays a video to further display prototype functionality as well as two air muscles for the public to see and touch. Lastly, our team will hand out project overview sheets which include a QR code to direct visitors to our Edge site.

Moderate Case Scenario:

In this scenario, our team will demonstrate a working prototype to the public with a team member as the volunteer; however, we will only be able to demonstrate the prototype on flat ground because our booth is not near stairs. Alongside our demonstration, we will still include our team poster as well as project overview sheets and two air muscles. Additionally, we will not include a video in our presentation in this scenario due to lack of table space for a computer or because of technically difficulties.

Worst Case Scenario:

The worst case scenario would be that we are unable to get our prototype to work properly. In this case, we would display our prototype on the table as well as our poster that summarizes our progress and our predicted theoretical analysis, simulations and feasibility test results, and CAD models. The main focus in this situation will be on what was learned and how our group plans to address the remaining address.

Elevator Speech

Our senior design project is an active ankle foot orthotic. This is an assistive walking device that is utilized by individuals with Foot Drop condition. Foot Drop is a neurological disorder which impairs the ability of an individual to dorsiflex the foot (i.e. point the toes upward) and is often a side effect of a stroke, ALS, Multiple Sclerosis, or a peroneal nerve injury. Current AFO’s are bulky, rigid, and disrupt the user’s natural gait by providing assistance at all times, regardless of need. An active AFO will provide users with assistance only during appropriate times in the gait cycle through the use of an air muscle. This timing will be determined using a Heelstrike sensor to measure gait and a distance sensor to distinguish terrain. The air muscle will be filled with compressed air from an air tank; this will make the AFO untethered, a feature that has not been completed by a senior design team at RIT. This device is not a replacement for medical treatment- it is simply a device to assist someone with walking.

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MSDI Business

MSD I Action Items
MSD I Postmortem
MSD I Improvement Plan
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MSDII Project Plan

MSD II Working Timeline

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MSDII Test Plan

Working MSDII Test Plan

Test Number	Test Plans
1	Ankle-foot Force Analysis
2	Power Analysis
3	Ease of Application Test
4	Survey of Orthotic Aesthetics
5	Ingress Protection
6	CAIR Capacity
7	Noise Test
8	Corrosion Test
9	Sub-Terrain Test
10	Recording Gait Test
11	Wearability Test
12	Slow Motion Deflection
13	Strap Analysis
14	Extended Use Test
15	Attachment Fatigue
16	Air Leak Test

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Problem Tracking

Working Problem Tracking
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Failure Modes

Working Failure Modes
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Engineering Fruition Plan

Engineering Fruition Plan
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Updated Bill of Materials

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Electrical Build

Schematics

Schematic (left), Top Layout(Center) and Bottom Layout(Right)

Electrical Prototype

Tested Systems

• Power Input: Power connection and 5V regulator
• Power LED

Soldered Systems

• System Clock: 16 MHz microcontroller clock
• TO_AFO Connection
• TO_SOLENOID: Two drive circuits for the Solenoid control as well as a ground connection
• SD Card: Level shifter and MicroSD card shield as well as the 3.3V regulator

Unsoldered Systems

• TO_FLOW_SENSOR: Power and ground connections as well as an ADC input to read the flow control as needed.
• SERIAL_I2C: Debug connections to the I2C communication as well as the Serial line.
• Hardware Low-battery system

Mechanical Build

Component Housing Redesign

Motivation

There were multiple changes that needed to be made to the component housing that houses the sensors.

• O-Ring groove needed redesigned to properly contain selected O-Ring to ensure complete sealing of PCB board chamber
• Angle of chamber housing the IR sensor was corrected
• Bosses added to base of PCB board chamber to elevate board off the bottom surface
• Future changes- consider addition of threaded inserts to prevent stripping of threaded holes in the plastic part; additional lid customized to fit around the sensor if additional protection is necessary; main lid will be thicker to allow holes to be counter-bored to fit the necessary screws.

Component housing redesign

Associated Documents

O-Ring Gland Size Calculations
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Muscle Attachment Redesign

Motivation

Because of machining capabilities and materials available, some slight changes were made to the plugs that attach the McKibbon muscle to the AFO. However, none of these changes had a significant impact on the functionality of the McKibbon muscle or the AFO.

• Overall height of the part decreased
• Overall width of attachment section of the upper plug decreased
• Thickness of the base plate decreased
• Chamfers and slight insertion groove added for easy assembly and to keep the plug in place better
• Opening cut into the bottom lip of the base plate to provide more room for muscle and allow for better McKibbon muscle function.
• Back side of the lower plug flattened and sanded to prevent discomfort
• Pin hole not yet drilled due to lack of necessity and to allow for quick design modifications A/R

Assembly (left), Upper Plug (Center) and Base(Right)

The prototype components as well as the upper muscle assembly can be seen in the figures below:

Upper Plug (Left), Upper Base (Center) and Lower Plug (Right)

Upper Muscle Assembly

Associated Documents

Base Drawing
Upper Plug Drawing
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Lower Attachment Redesign

Motivation

After completing initial lower attachment force lift tests, our team decided that it would be best to incorperate a lift mechanism that would better allow users to apply and remove the AFO easily. In the original design, the fishing line was at a fixed location right above the adjustable strap, making it hard to users to access the strap. Additionally, our team was concerned with the fishing line stretching over time. The new design incorperates an A-shaped thin strap. This strap is more durable than the fishing line and its design allows users to easily access the velcro strap ontop of the foot. <b>

Lower Attachment: A-Shaped Thin Strap

Feasibility Test
The reason for this test is to find:

• How much force does it take to lift the foot using the newly added A-shaped strap?
  
• Does the lift remain comfortable when a force is applied?
  
• Does the A-shaped strap allow users to apply and remove the device easier?
  

Results:
Observations-

• Force was not distributed evenly at the base of the pull
• User experienced slight pain near base of toe when force was applied
• Strap sewing came undone and strap detached from brace at the end of the experiment

Trial	Force (lbs)
1	10.5
2	10
3	10.5
4	11
5	11
6	10.5
7	10.5
8	10.5
9	11
10	11
Average	10.6

Conclusion:

• The new strap allows the user to apply/remove the AFO easily because the Velcro strap is more accessible
• An additional 2lbs was required to lift the foot due to an uneven distribution of force at lift base. This will be addressed through brace modifications.

Next Steps:

• Sew the A-shaped strap onto the brace at an angle (see design below).
  

• Complete same test with modified design to determine whether or not the device is comfortable during lift and the amount of force to lift the foot is less than 10.6lbs.
  

Lower Attachment Strap Redesign Feasibility Test

Build Preparation Review

The review was conducted in week 2 based on this agenda
Phase 2 Meeting notes

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Home	Planning & Execution	Problem Definition	Systems Design	Subsystems Design	Detailed Design	Gate Review
MSD I	Team Members & Roles Project Plan Meeting Minutes, Notes, & Actions Team Values and Norms	Project Summary Use Scenario Customer Requirements Engineering Requirements Concerns and Risks Problem Definition Review	Functional Decomposition Morphological Chart Pugh Chart System Design Performance Limits Risk Assessment System Design Review	Phase Planning Electrical Testing Mechanical Testing CAD Models Build, Assembly, and Debug Plan Bill of Materials Risk Assessment Subsystems Review	Phase Planning Mechanical System Concept Electrical System Concept Bill of Materials Risk Assessment Detailed Design Review	Phase Planning System Design Bill of Materials Build, Assembly, and Debug Plan Electrical System Concept Mechanical System Concept Risk Assessment Gate Review
	Build Preparation	Build & Test	Integrate & Assemble	System Validation	System Verification	Final Review
MSD II	Phase Planning Imagine RIT Shared Vision MSDII Test Plan Problem Tracking	Phase Planning Engineering Requirements Problem Tracking Mechanical Build Integrated Prototype Electrical Build	Phase Planning Engineering Requirements Problem Tracking Updated System Design Electrical Build Nazareth Clinic	Phase Planning Engineering Requirements Problem Tracking Updated Board Design Wearibility Testing Nazareth Clinic Imagine Deliverables	Phase Planning Engineering Requirements Problem Tracking New Muscle Testing RIT Subject Testing Imagine RIT	Performance vs. Requirements Budget Tracking Electrical Design Mechanical Design Assembly and Build Plan Next Steps