P19095: LiveAbility Lab
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Preliminary Detailed Design

Table of Contents

Team Vision for Preliminary Detailed Design Phase

Following the systems design review, it became apparent that the F-Scan system did not have the durability to be integrated into a robust system. A tekscan sales representative informed us that the lifetime of the part was at best ~ 8 minutes. Our second choice for an in-sole force sensor costs around $20,000.00 which is clearly not an option. This phase involved rolling back to concept selection and choosing a new candidate for force measurement. This involved us taking a closer look at our customer and engineering requirements. Another important event in this phase was the meeting with Dr. Dombovy, Jan Scott, and Chris Streeter. The meeting helped clarify some of the goals for the project regarding the force measurement. The feedback we received helped us to decide on solutions involving force sensors, accelerometers, and a beacon positioning system. We have ordered a set of the A301 force sensors from Tekscan. Once they arrive, the goal will be to test the resolution as well as the integration capability in relation to the Raspberry Pi. The Raspberry Pi 0W has been selected as the single board computer to act as the local brains of the system. The Raspberry Pi 3B+ and BeagleBone Blue are both being evaluated as potential system backbone contenders. The MBIENT MMR is an accelerometer which has been used by RIT faculty for similar research projects, in the next phase we will evaluate its feasibility in determining force and position as well as the gait analysis. Further research will be conducted in the determination of a cost effective and accurate beacon system.

Feasibility: Prototyping, Analysis, Simulation

Updated Customer and Engineering Requirements

Updated Customer Requirements

Updated Customer Requirements

Updated Engineering Requirements

Updated Engineering Requirements

Force Sensor Analysis and Feasibility

During this phase we examined several new possibilities in detail for force sensors, given that our focus in previous phases turned out to be insufficient for our needs. During our research, we found a study that examined the foot pressure distribution of individuals of all ages. This study determined that the area of the foot that produces the most amount of force is the heel, followed by the ball of the foot. It also concluded that young individuals can step with almost 3.5x the force of their body weight, while elderly individuals can step with 2.5x their body weight. While this study only examined healthy individuals and had a relatively small sample size, it provided us with some initial parameters to start with. We have decided to use Tekscan’s A301 sensor in order to measure the force, which can be configured to measure up to 1000 lbs. Four of these sensors will be integrated into the insole of each shoe, two at the heel and two at the ball of the foot, in order to measure the force at these high impact areas.
Force Sensor Updated Benchmarking

Force Sensor Updated Benchmarking

Location Sensor Analysis and Feasibility

In terms of the location measurement, we have decided to utilize an RF Beacon system to measure the individual’s position, as this is a novel technology in this application. We plan to supplement the Beacon system with an accelerometer due to the detailed gait analysis this can provide.

Accelerometer

Accelerometer

Accelerometer Output

Accelerometer Output

Drawings, Schematics, Flow Charts, Simulations

Updated Systems Architecture

Updated Systems Architecture

Updated Systems Architecture

Updated Systems Architecture With Power

Updated Systems Architecture With Power

Pressure Sensor Positioning

Foot Pressure Map

Foot Pressure Map

Image complementary of Dr. Sholl's. Additional data complementary of Innssi.com
Sole Sensor Placement

Sole Sensor Placement

Shoe Attachments

The microcontroller, accelerometer, and op-amp circuit will need to be attached to the individual's shoe. Our goal is to attach these components in such a way that is compact, light weight, and minimally invasive to the individual.

Shoe Attachment Option 1

Shoe Attachment Option 1

Shoe Attachment Option 2

Shoe Attachment Option 2

Power Regulation

Power Regulation Schematic

Power Regulation Schematic

Power Regulation Simulations

Power Regulation Simulations

Bill of Material (BOM)

BOM

BOM

Interfacing Sensors and Micro-controller

Interfacing sensor and microcontrollers

Test Plans

Test Plans

Test Plans

Risk Assessment

Risk Management Chart

Risk Management Chart

Risk Highlight: Purchasing

At the beginning of this phase, the group had its purchasing procedure changed. Our project is now funded through the Simone center and all purchases will be processed there instead of through PICS. The risks come from using an unfamiliar process whereas we were trained using the PICS system. This has already caused an ordering issue which was quickly rectified. The corrective action as a result of this issue is to remain extra diligent and specific when ordering parts while keeping good communication with the Simone center.

Risk Highlight: Resistive Force Sensors

The resistive force sensors that the team has specced out are supposed to take more than enough force and be flexible enough to contour a foot. They still need to be tested and confirmed that the sensors are able to do everything our system will need them to do.

Risk Highlight: Calibration

Calibrating the accelerometers and force sensors is extremely important. The team must go about this step carefully and diligently. This step will affect how the testing goes and allow the team to accurately decide if the parts are going to be used in the system.

Risk Highlight: Erik

Goodbye Erik

Goodbye Erik

On April 1st 2019 Erik Brown signed with the Toronto Marlies. We are all very happy for Erik and wish him luck in his endeavors. The announcement came as a surprise to the team who did not expect him to be leaving so soon. To mitigate the risk, the team will communicate with Dr. DeBartolo ahead of next semester to see if there is any way to add a Biomedical Engineer to the team as we feel there is a definite need for that skill set, especially in the implementation and testing phase.

Plans for next phase

Team Goal for Weeks 12-15

The team goal for the next phase is primarily to order and test. The team will be receiving components throughout the next phase and they will be tested in the order received. The most important component to evaluate is the accelerometer and determine its feasibility as a location sensor. If the accelerometer is not a viable option for this, a beacon system will be used in its place. The desired state at the end of the phase is to have ordered and received all components to build the device so we can begin prototyping at the very beginning of the next semester.
Gantt Chart

Gantt Chart

Individual Responsibilities to Achieve Team Goals

Martine Bosch
Nick Petreikis
Matthew Devic
Patrick Mylott
John LeBrun
Hrishikesh Moholkar

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