Hip position classification device

Van Niekerk, Philippus Johannes (2019-04)

Thesis (MEng)--Stellenbosch University, 2019.


ENGLISH ABSTRACT: Robust, user-friendly hip position tracking device that is capable to function outside of a lab environment can lead to valuable progression in the hip impingement research field. This project discusses the design and testing of such a device. The device developed functions by tracking a permanent magnet on the thigh with magnetometers placed on the pelvis to classify the relative angle between the pelvis and the femur (hip angle). The position tracking device only tracks if the user reaches a specific hip angle that is of interest. The angle is set by the user in the calibration procedure. The device classifies the position of interest, as indicated by the user, with a k-nearest neighbours (k-NN) algorithm. The device was verified for accuracy against a Vicon Vantage motion capture system. Five participants took part in the study structured in a two-tier structure. The first tier was to evaluate the method of motion capture. The second tier’s objective was to verify the accuracy of the device. The algorithm output is the amount of calibrated "nearest neighbours" expressed as a percentage activated at the current pose. For a 100 % output, the device is accurate below 5 o in all three anatomical angles of the hip.

AFRIKAANSE OPSOMMING: 'n Robuuste, gebruikersvriendelike heup posisie metingstoestel wat buite 'n laboratorium gebruik kan word sal ‘n geweldige bydrae lewer tot die heup impingement navorsingsveld. Hierdie projek bespreek die ontwerp en toets van so 'n toestel. Die toestel is geverifieer vir akkuraatheid teen 'n Vicon Vantage bewegingsopvangstelsel. Vyf deelnemers het deelgeneem aan die studie wat gestruktureer was in twee vlakke. Die eerste vlak was om die metode van bewegingsopname te evalueer. Die tweede vlak was om die akkuraatheid van die toestel te verifieer. Die toestel wat ontwikkel is funksioneer deur die magneetveld om ‘n permanente magnet te meet. Die magneet word geplaas op die femur en die magnetiesesensore op die bekkenbeen. Die relatiewe hoek tussen die bekkenbeen en die femur (heuphoek) kan so bereken word en geklassifiseer word. Die toestel meet slegs as die gebruiker 'n spesifieke heuphoek wat van belang is bereik. Die hoek word deur die gebruiker in die kalibrasieprosedure gestel. Die toestel klassifiseer die posisie van belang, soos aangedui deur die gebruiker, met 'n k-naaste bure (k-NN) algoritme. Die algoritme-uitset is die hoeveelheid gekalibreerde "naaste bure", uitgedruk as 'n persentasie. Vir 'n 100 % uitset is die toestel akkuraat onder 5 o in al drie anatomiese hoeke van die heup.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/106230
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