Preliminary Detailed Design
Table of Contents
Team Vision for Preliminary Detailed Design PhaseFollowing 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
Force Sensor Analysis and FeasibilityDuring 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.
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.
Drawings, Schematics, Flow Charts, Simulations
Updated Systems Architecture
Pressure Sensor PositioningInnssi.com
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.
Bill of Material (BOM)
Interfacing Sensors and Micro-controllerInterfacing sensor and microcontrollers
- Snapshot of your current risk assessment as well as a link to the live document.
Risk Highlight: PurchasingAt 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 SensorsThe 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: CalibrationCalibrating 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
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.
Individual Responsibilities to Achieve Team Goals
- Martine Bosch
- Perform tests on A301 force sensor. (3 hours)
- Design attachment to leg of a crutch/walker/cane. (2 hours)
- Begin prototyping integration of sensors into the insole of a shoe and perform testing. (5 hours)
- Nick Petreikis
- Assist in evaluation of A301 (3 hour).
- Acquire MMR accelerometer and evaluate location feasibility (5 hours).
- Continue purchasing components (X hours).
- Matthew Devic
- Test/Build A301 Op-Amp circuity for calibration (5 hours).
- Test feasibility of power regulation circuity designed in phase 3 (5 hours).
- Finalize parts list with other lead engineers for all systems (5 hours).
- Patrick Mylott
- Continue to update the gantt chart for the project (3 hours).
- Assist with all testing and prototyping.
- John LeBrun
- Test and troubleshoot power deliver for the entire system (microcontroller, accelerometer, pressure sensor).
- Develop Charging scheme for system battery.
- Continue on with the weekly State-of-the-Project emails
- Hrishikesh Moholkar
- Research the MCU and IDE to use for developing the firmware for sensor.
- Add more cases and improve the UML diagram for the sensor software.
- Help team in research.