Design of an Apparatus to Measure Elbow Spasticity
Team 5: Kevin Glick, Allison Heil, Michelle Cunanan
Clients: Dr. Steve Tippett & Dr. Elizabeth T. Hsiao-Wecksler
Advisor: Dr. Julie Reyer Course Coordinator: Dr. Martin Morris
Objective1. Demonstrate the ability to quantify elbow spasticity & rigidity
2. Provide sample data for an elbow spasticity simulator
Design & Analysis
Our prototype can be seen in the images below.
Left: FSR and flex sensor are mounted to a compression sleeve and
connected to the microprocessor (snowboard).
Right: Modified Snowforce interface provided by Kitronyx that
displays force in 2D and angular position output
Design Constraints:
Spasticity and rigidity can be characterized using position, torque,
velocity, and torque rate• Angular position limited to a range of 0° to 135°
• Angular velocity will be limited to a range of ±400 deg/s
• Angular acceleration limited to a range of ±2000deg/s²
• Torque limited to a range of ±10 Nm
Selected Sensor Package:• Spectra Symbol 4.5” Flex Sensor
• Resistance across the sensor increases as the
sensor is flexed
• Needs to be calibrated before each use
• Outputs angular position (degrees) to text file
• Sensitronics ThruMode Matrix Array• An array of 160 force sensing resistors (FSRs) that allows
the user to measure force over the 2”x 3” sensing area
• Calibrated with known masses
• Outputs resistance that can be converted to force via post
processing data analysis
• Kitronyx Snowboard• Arduino Leonardo with integrated force and touch sensing
controllers
• Access to Snowforce interface with editable Arduino and
Processing codes that are compatible with FSR array
Schematic:
Value to Client• Simulation Education: Data collected can be implemented into
a robotic elbow to stimulate elbow spasticity/rigidity.
Budget
Total Cost: $279.92
Project ProgressionGantt Chart
Deliverables• A working prototype measuring device
• A final report including a recommendation for sensors for a
future measuring device
• A database in Excel that holds all of the experimental data taken
with final prototype
Initial Concepts/Down-Selection Motion Capture Load Cell & Rotary Encoder
Torque Sensor
Accelerometer
Rotational Potentiometer
Inertial Measurement Unit (IMU)
AcknowledgementsBradley University Mechanical Engineering Department:
Dr. Julie Reyer Dr. Richard Johnson Gayle Dezner
Bradley University Physical Therapy Department:
Dr. Melissa Peterson Kristen Tetuan Sharon Key
Additional Acknowledgements:
Deepak Gaddipati James O’Connor
Carrie Liang Alex Ferrebee
Product Qty Total Cost
Kitronyx Snoboard with Sensor Package 1 $ 144.99
Spectra Symbol Flex Sensors 4 $ 45.58
Sensitronics Force Sensitive Resistor Matrix Arrays 2 $ 31.83
Hardware (Jumper Wires, Shift Registers, Multiplexers) N/A $ 57.50
Background• Elbow spasticity is a velocity-dependent stiffening of the
muscles that affects the motion in the elbow
• Rigidity is the stiffness or inflexibility present in both agonist
and antagonist muscles, and is characterized by the increased
resistance to passive movement.
• Currently measured using a
passive stretch-reflex test that
has limited sensitivity and is
highly subjective
• Current measurement analysis techniques are qualitative no
quantitative
Modified Ashworth Scale:
Recommendations• Develop a more user-friendly interface
• Use a higher quality sensor to collect position (i.e. fiber optic
goniometer or potentiometer)
• Complete HSRB process to conduct testing on actual patients• If testing actual patients, pay attention to dτ/dt (“jerk”)
• Perform in-situ measurements that is minimally invasive
• Pressure mapping system that can calculate a net pressure in specific
direction (i.e. Pressure Profile Systems Company)
• Create wire connections with more conductors than a 4 stranded wire
McGibbon, C. A., et al. "Elbow Spasticity during Passive Stretch-Reflex: Clinical Evaluation using
a Wearable Sensor System." Journal of NeuroEngineering and Rehabilitation 10.1
(2013)SCOPUS. Web. 23 Sep. 2014.
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