P11011: M OTION -T RACKING S YSTEM F INAL D ESIGN R EVIEW Brittany Bochette Lindsey Clark Mike Ostertag Maya Ramaswamy Andrei Stihi

P ROJECT B ACKGROUND Motion-tracking system that measures knee flexion and head-tilt Continuation of past senior design groups P10010 Sensors P10011 Attachment Methods Customers are Nazareth Physical Therapy Clinic and Rochester General Hospital

K EY C USTOMER N EEDS Measurement +/- 80 degrees of tilt and +/- 100 degrees of rotation Accuracy 5-10 degrees error Reproducibility 5-10 degrees Speed of Attachment and Removal 2 minutes, 5 seconds

C ONCEPT O VERVIEW FTDI 3.3V Breakout Board Razor 9DOF IMU USB Brass screws Attachment Snaps Foam stabilizer Protective enclosure

S YSTEM A RCHITECTURE

Base Unit S YSTEM A RCHITECTURE Knee Flexion Head-Tilt Options Quit USB

A TTACHMENT M ETHODS Head attachment and enclosure Leg attachments with enclosures

E NCLOSURES Internals: Brass screws and nuts were used, along with rubber washers for interference free operation Foam padding was used on the backside to stabilize it when used with various attachment methods through the use of snaps

D ETERMINING K NEE F LEXION Sensor is placed on the side of the leg with gravity being felt in the X and Y components of the accelerometer The orientation of the sensor relative to gravity was calculated with Equation 1. The amount of flexion is the difference between the two angles as seen in Equation 2. Eq. 1 Eq. 2 X Y Z AgAgAgAg

D ETERMINING H EAD O RIENTATION Head has complex motion due to three-axes of rotation Breaking down motion to three individual axes (seen above) simplifies the process of determining orientation AnterocollisRetrocollisLaterocollisTorticollis

D ETERMINING H EAD O RIENTATION Antero/retrocollis (pitch) and laterocollis (roll) were determined using a three-axis accelerometer Angles were determined by comparing the components of acceleration caused by gravity (A g ) Eq. 3 Eq. 4 X Y Z AgAgAgAg

D ETERMINING H EAD O RIENTATION Torticollis (yaw) was determined using the three- axis magnetometer and the following procedure: 1. The magnetometer readings were corrected for tilt based upon the pitch and roll found previously. 2. A current magnetic heading was found with the following equation: 3. The difference between the initial and current magnetic heading is the amount that the head has rotated. Eq. 5 Eq. 6

T ESTING 30˚ rotation in the pitch, roll, and yaw directions Changes in degree during four knee flexion cycles

R ESULTS SpecificationExpectedActual Measurement Tilt: +/- 80˚ Rotation: +/- 100˚ Tilt: +/- 90˚ Rotation: +/- 180˚ Accuracy5-10˚ Roll: within 5˚ Pitch: within 10˚ Yaw: within 8˚ Precision5-10˚ Roll: 2˚ Pitch: 6˚ Yaw: 2˚ Speed of attachment/removal 2 minutes/5 seconds28 seconds/3 seconds

C URRENT S TATE OF D ESIGN Design is functional Meets all engineering specifications except Measurement of shift –discussed this with the customer and it is an option for future designs Budget requirements - $1000 allowed, $ spent After changing scope, we used the more expensive Razor IMU for both systems This caused a slight budget overrun for the knee device On schedule with exception of rescheduled D3 meetings ExpectedActual Dr. Mowder$300$315 Dr. Barbanounlimited$315

R ISK A SSESSMENT Contacting our customers and scheduling meetings with them proved to be one of the most relevant risks. The device not meeting customer needs was also something that was a possible risk up until week nine. Not being able to communicate with the base unit was another risk we had to address

P ROJECT E VALUATION Project was originally scoped too large The intent of the project became clearer after a re-scoping at the end of MSD I Base unit and sensor sub-systems should be one group With a similar project, a prototype should be the first step rather than a fully functioning system

R ECOMMENDATIONS Being able to measure shift of the head would be something desired by Dr. Barbano in the future. Dr. Barbano also voiced a need to have something on the device that helped him to level the device on the patient so that human error was reduced or even eliminated. Dr. Mowder suggested using Dysom or some other rubber-like material to prevent the strap on the calf from slipping