DETAILED DESIGN REVIEW GROUP MEMBERS: Irma Bocova Rob Bowman Phetphouvanh “Awt” Phommahaxay Kyle Pilote Jeff Rebmann Chris Rowles Faculty Guide: Dr. Elizabeth DeBartolo November 6 th, 2009 Mechanical Spine Test Platform P10007

Agenda Desired Outcomes – 11:00am Project Background – 11:05am Mechanical Design – 11:15am  Drawings/Schematics  Feasibility Calculations Electrical Design – 11:35pm  Selection  Accelerometer issues  MicroStrain 3DM sensor Output Design – 11:55pm Bill of Materials – 12:10pm Risks/Feasibility – 12:20pm Preliminary Test Plan – 12:40pm Next Steps

Desired Outcomes of Review Receive input on selected concept Identify and discuss key risks:  Sensor interference Discuss LabVIEW

Mission Statement The intent of this project is to design and build a test platform that will mimic the actions of a human spine. This design will incorporate movements in three dimensions, while being able to independently measure the angles and linear adjustments. The purpose of developing this platform is to validate the data from an existing measuring device in use at the Nazareth Physical Therapy Clinic.

Project Description Project Title: Project Title: Mechanical Spine Test Platform Primary Customer Primary Customer  Dr. Sara Gombatto  Professor at Nazareth College of Physical Therapy  Dr. JJ Mowder-Tinney  Director of Clinical Education Nazareth College Department of Physical Therapy  Physical therapy patients Secondary Opportunities Secondary Opportunities  Further spinal iterations

Background/Application Nazareth Physical Therapy Clinic motion capture system  Allows motion capture of PT patients in order to track progress Validation of existing motion captures Focus on spinal segments Secondary Application:  Portable Motion Tracking System calibration Source: Source:

Customer Needs Three tiered approach to group needs and limit scope  Base Plan  Aggressive  Outstanding Example Need: Must be moveable in distinct segments  Base Plan – Two distinct sections (Lower & Upper Lumbar)  Aggressive – Three distinct sections (Lower & Upper Lumbar, Thoracic)  Outstanding – Divide Thoracic segment into multiple segments Highest Ranked Needs – Base Plan Needs to be able to measure angle deviations for all sections relative to the section below it Use a tight tolerance for measurements Provide measurements in all three planes of space (x, y, z) Needs distinct sections of the spine to be able to move Needs to be adjustable lengthwise in order to simulate different size spines Movements needs to be lockable so that an accurate measurement can be read The height of the device has to be the level of a spine of a person standing in an upright position Needs to have a “zero” position for all sensors/joints

Engineering Specifications Correspond to highest ranked Customer Needs: SpecificationUnits Base Plan Value Aggressive Value Outstanding Value Must have a minimum tilt in all directions relative to the section below degrees +/- 15 Angle tolerancedegree+/- 1.0 Must have a tilt in all directions relative to the section below planes 3 (sagittal, transverse, frontal) Must be movable in distinct sections and a fixed base (pelvis) movable sections 2 (lower lumbar, upper lumbar) 3 (thoracic)Divided thoracic Should be able to fit all required ranges needed by customer vertically millimeters for each lumbar segment 200 – 300 for thoracic segment Joint holding strengthN*m 0.13 Device must mimic a person standing in an upright position - Trochanterior Height millimeters Device has mechanical "zero" positionYes/No Yes

System Architecture

Final Concept

Final Assembly Picture-Isometric View

Final Assembly Picture-Front View

Final Assembly Picture-Side View

Mechanical Calculations

Mechanical Calculations(cont’d)

Electrical Selection Analog Devices- Adxl202 accelerometer MicroStrain’s- 3DM

Microstrain 3DM Magnetometers and accelerometers are used to compute pitch, roll, and yaw. Output provides raw magnetic field and accelerometer outputs, or pitch, roll, and yaw outputs. Communication through a serial port.

MicroStrain 3DM Sensor Specifications Range Yaw: 180˚ Pitch: 90˚ Roll: 180˚ A/D Resolution12 bits Digital Filter Infinite Impulse Response (IIR) User programmable weighted moving average Angle Resolution (no digital filtering) Pitch: 0.30˚ (typical) Roll: 0.25˚ (typical) Yaw: 0.50˚ (typical) Angle Resolution (most aggressive digital filtering) Pitch: < 0.1˚ Roll: < 0.1˚ Yaw: < 0.1˚ Resolution specs. taken during static motions Accuracy Pitch: 0.93˚ typical (yaw from ˚ and roll=0˚) Roll: 0.33˚ typical (yaw from ˚ and pitch =0˚) Yaw: 1.0˚ typical (pitch and roll=0˚) Accuracy is defined as the square root of the sum of the errors squared (non-repeatability, temperature coefficients and nonlinearity).

MicroStrain 3DM Sensor Specifications Angle measurement nonlinearity (pitch and roll) 0.23% F.S. Angle measurement repeatability Pitch: 0.07˚ (typical) Roll: 0.07˚ (typical) Yaw: 0.26˚ (typical) Update rate (angle mode) 45 Hz/3 channels (maximum) 30 Hz/3 channels (typical) Update rate is specified with a maximum and typical value since it depends on how many points the A/D converter averages. Update rate (raw mode)70 Hz/ 6 channels Output modes Raw accelerometers and magnetometers, Euler angles, matrix, accelerometers and magnetometers vector Output formatRS-232 serial Transmission Rate9600 bits/sec Supply voltage+5.2 VDC min., +12 VDC max. Supply current50 standard speed ConnectorsSensor: RJ11 type power: min. coaxial jack Operating Temperature- 25˚C to 70˚C Temperature Drift (%/˚ C) Pitch: +/ %/deg C (mean, std.dev.) Roll: +/ %/deg C Yaw: +/ %/deg C Module size1.7" wide, 2.5" long, 0.7 " thick Weight75.0 gr. with enclosure, 26.9 gr. without enclosure 3DM ® enclosure (.pdf file) 3.5" wide x 2.5" long x 1.0"

Calculations The sensor outputs the orientation information in 3 different forms: 1) Euler Angles 2) Quaternion 3) 3x3 Rotational Matrix Orientation in the form of Rotational Matrix is given in the form: Orientation in the form of Euler Angles is derived from the rotational matrix. (Calculated using “aircraft”) Elevation (pitch) Bank (roll) Heading (yaw)

Calculations The rotational matrix can be calculated from a set of Euler angles using the equation below:

Process Estimated times are given for each task in the process. This allows for an estimated total process time as well as expected maximum and minimum times.

LabVIEW Interface will allow user to see the angular displacement of the pitch, roll, and yaw of the Lower Lumbar and Upper Lumbar segments based on output from the sensors Customer will download free LabVIEW Run-Time Engine Output will run as an executable program application  User can only use the application, not change coding

Bill of Materials BOM

Risk Assessment (Mechnical) Risk EffectCause Probability Severity Overall Risk Contingency Response Design unrepairableOnce broken, unusable new parts unattainable, too hard to repair 4832 Make easy to build and replacable sections/parts Stand Instability Device tips over causing possible damage Members exceed center of mass 236Use a larger counter weight Ball Joint Mechanical zero device is ineffectiveInaccurate measurements Bending of materials 236Stiffer materials Inadequate clamping force Joints will not hold static position Too much spine weight 133 Increase size of bolt and knob, re- design Joint is too largeSkew measurementsLack of options224Adjust member lengths to fit system Joint may gradually wear over multiple cycles Will not hold a static positionWear over time122 Provide information for a replacement part Multiple Members Non reflective finish on contact surfaces may wear over time Introduce IR interference Wear between touching parts 224 Anodize or powder coat material Use a non reflective material Members do not connect properlySkew measurementsPoor machining236Machine to a tight tolerance Lowest range position may interfere with movement Does not allow 20 degrees of tilt Small connections 313 Limit the low end range of adjustability, only satisfy a percentage of the ergonomic range Fixed Horizontal Members Collision with other horizontal members when linear adjustment is at low end range Does not allow 20 degrees of tilt Small connections 339 Make the horizontal members foldable Rotate members out of plane

Risk Assessment (Electrical) Risk EffectCause Probability Severity Overall Risk Contingency Response Sensor Interference between the sensors. Inaccurate/ no measurements.Sensor technology.212Contact company for concerns. Sensor durabilityNon-operational device.Sensor technology, misuse224 Provide backup sensors. Attain warranty. Unable to test sensor accuracy Not meeting customer’s needs of measurement accuracy Lab and tools availability to verify accuracy 224 Possible modification of customer’s needs with customer Sensor not accurate to 0.1 degree of tilt or rotation Not meeting customer’s needs of measurement accuracy Sensor defects or improper specs 339 Possible modification of customer’s needs with customer If required, sensors not returned within 30 days for full refund Loss of fund and development time 30 days return policy224Return before 30 days 3DM Magnetic/electrical interference between sensors Incorrect measurement of rotational and tilt angle Magnetic/electric field effecting the sensors 339 Test and validate effects between sensors. Test for magnetic response Magnetic interference between sensors and test site Not meeting customer’s needs of measurement accuracy Magnetic/electric field at the test location effecting the sensors 236 Test and validate effects of sensors and test location for accuracy. Use software offset Magnetic interference between sensors and metallic parts Incorrect measurement of rotational and tilt angle Magnetic field effecting the magnetometer 236 Test and validate effects of sensors and metallic parts Use software LabVIEW Unable to program LabVIEW Incorrect output of measurements Lack LabVIEW experience236Seek professional service/advice Hardware and software No communication between 3DM and LabVIEW No output measurements Signal recognition between hardware and software 236 Professional service/advice from manufacture of hardware and software

Preliminary Test Plan(Mechnical) Spine Size Verification Test This test is designed to verify the dimensional constraints of the spine model. Specifications Tested: 1.1, Visual Inspection Test The purpose of this test is to verify all non- measureable traits of the spine model. These are specifications that do not have associated dimensions, tolerances or values, but simply are present or are not. Specifications Tested: 3, 4, 5, 22 IR Interference Test The purpose of this test is to verify that the material finish of the spine model is non-reflective and does not interfere with the customers IR camera system. Specifications Tested: 7 Joint Holding Strength Test The purpose of this test is to verify that the adjustable ball joint is capable of locking in any given position and can support the weight of a fully articulated spine model. Specifications Tested: 17,22

Preliminary Test Plan (Cont’d) Durability/Wear Test The purpose of this test is to test the wear and functionality of the joints and adjustable member sections after repeated use. Specifications Tested: 18 Overall Weight Test The purpose of this test is to measure the overall weight of the device, which is part of the usability. Specifications Tested: 19 Marker Placement Test The purpose of this test is verify that the customer is able to mount the reflective markers in the proper location. Specifications Tested: 20 Mechanical Zero Test The purpose of this test is verify that the mechanical zero device is properly calibrated. Specifications Tested: 21

Preliminary Test Plan (Electrical) Sensor Measurement Verification This test will verify the digital measurement with the physical measurement of the mechanical spine. The test will also verify whether the sensor accuracy meets the customer’s needs. Specification Tested: 6, 12

Next Steps… Implement action items from Detailed Design Review Actively test ball joint drilling Order long lead time parts Update EDGE with latest information Create MSD II schedule