Graduation Year


Document Type




Degree Name

MS in Mechanical Engineering (M.S.M.E.)

Degree Granting Department


Major Professor

Kyle B. Reed, Ph.D.

Committee Member

Theresa A. Zesiewicz, M.D.

Committee Member

Oscar Rios, Ph.D.


Clinical Devices, Gait Analysis, Instruments, Measurement, Neurodegenerative Disease


Friedreich Ataxia (FA) is a debilitating autosomal-recessive neurodegenerative disorder which is characterized by ataxia of all four limbs, difficulty walking, areflexia, and dysarthria. Further complications of FA include diabetes, scoliosis, and hypertrophic cardiomyopathy. Approximately three-quarters of people with FA have onset before the age of 25 and in most instances, affected individuals will require the use of a wheelchair within ten years after symptoms emerge.

The current advancements in clinical trials have escalated the developmental demand for a scale which validates adjustments in FA. The Friedreich Ataxia Rating Scale (FARS) is a disease-specific semi-qualitative assessment which includes three subscales (functional staging, activities of daily living and neurological) and functional performance measures (nine-hole peg test, timed 10-meter walk test and the PATA rate) where a greater FARS score correlates to a more severe progression of ataxia. Several studies have determined that FARS meets strict standards for construct validity in measuring the progressive nature of FA. However, FARS is administered subjectively, by varying trained evaluators, which ultimately places an upper limit to its sensitivity and reliability.

This thesis focuses on quantifying the heel to shin tap, heel along shin slide, finger tap and 10-meter walk portions of the FARS exam. A device, or system of devices, was designed, created and tested on healthy subjects to demonstrate the human errors that are introduced within the current exam procedures. Along with the device, the normal subjective procedure was utilized, with visual inspection and mental tabulation for each test administered.

The heel to shin device was very precise when compared to the manual subjective counts, where only two of the twenty-five tests included any type of error. The error for this device may have stemmed from the patient's strain to view the target location which will diminish with the use of a foot prop or footrest. The heel along shin slide device was also precise when compared to the subjective manual counts with only three of the twenty-one tests including any type of error. However, future improvements must be made by replacing the two 408 force resistive sensors (FSR’s) with a single FSR of equal dimensions and inserting another sensor in the proximal portion of the shin. The finger tap device had linear potentiometer errors in thirteen of the twenty-three tests, but zero errors associated with its FSR. In the future, the linear potentiometer must be replaced with another sensor that requires a lower minimum actuation force. The 10-meter walk is measured with a system of four very reliable and accurate devices, but the current defuse-reflective sensors are limited in their ability to view colored clothing. The defuse-reflective sensors can be replaced by more accurate retro-reflective sensors, but they require receivers on both sides of the walkway.