Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2009. / Percussion is a centuries old bedside diagnostic technique that is used to diagnose various conditions of the
thorax and abdomen, among these, abnormalities of the liver. The physician taps the patient’s skin in the area of
interest to determine the qualities or presence of the underlying tissue or organ, by listening to the generated sound.
The research contained in this thesis views percussion as a system identification method which uses an impulse
response to identify the underlying system. A design employing an electromagnetic actuator as input pulse
generator and accelerometer as impulse response recorder was motivated and built.
Tests were performed on volunteers and the recorded signals were analysed to find methods of identifying the
presence of the liver from these signals. The analyses matched signals to models or simply extracted signal features
and matched these model parameters or signal features to the presence of the liver. Matching was done using
statistical pattern recognition methods and the true presence of the liver was established using MR images. Features
extracted from test data could not be matched to the presence of the liver with sufficient confidence which led to the
conclusion that either the test, apparatus or analysis was flawed.
The lack of success compelled a further test on a mock-up of the problem – a silicone model with an anomaly
representing the organ under test. Results from these tests showed that signals should be measured further from the
actuator and the approach followed during this test could lead to the successful location of the anomaly and
discrimination between subtle differences in the consistency thereof.
It is concluded that further research should aim to first validate percussion as performed by the physician and
increase complexity in a phased manner, validating results and apparatus at each step. The approach followed was
perhaps too bold in light of the lack of fundamental understanding of percussion and the underlying mechanisms.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/2331 |
| Date | 03 1900 |
| Creators | Rauch, Hanz Frederick |
| Contributors | Scheffer, C., Van Rooyen, G-J., University of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Stellenbosch |
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