Improving goniometer accuracy by compensating for individual transducer characteristics.
Flexible goniometers are useful for direct movement measurements. Crosstalk due to rotation between the endblocks is well known. However, even without any rotation, some crosstalk can occur. The objective of this study was to elucidate the effect of, and compensate for, the inherent crosstalk in biaxial goniometers, with specific relevance for applications with one dominating movement direction. Six biaxial goniometers (M110, Biometrics Ltd., Gwent, UK) were evaluated. A precision jig, for simulating pure flexion/extension angles, was constructed. Each sensor produced a consistent and specific crosstalk pattern, when tested over a +/-100 degrees range of motion. A procedure for correction for the inherent crosstalk of individual goniometer, based on polynomial adjust, is presented. The method for compensation, which reduced the root mean square error from, on average for the six goniometers, 3.7 degrees (range 1.8-10.1 degrees) to 0.35 degrees (0.12-0.55 degrees), might be required for obtaining valid goniometer measurements, e.g. of valgus/varus of the knee during gait flexion/extension movements.
Sato
Tatiana de Oliveira
Tde O
Department of Physical Therapy, Universidade Federal de São Carlos, CP 676, CEP 13565-905, São Carlos, SP, Brazil.
Coury
Helenice Jane Cote Gil
HJ
Hansson
Gert-Ake
GA
D000465:Algorithms; D053587:Arthrometry, Articular / Q000295:instrumentation* / Q000379:methods*; D016477:Artifacts; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers