Methodological Analysis Of Fintie Helical Axis Behavior In Joint Kinematics

摘要: SUMMARY The Finite Helical Axis (FHA) is still confronted with representational difficulties. The present study investigates the effect of noise in estimation parameters. Furthermore, a method presented to describe axis dispersion as way demonstrate stability and quality joint movement. Optimal reduction angle intervals are well minimum Convex Hull method. INTRODUCTION Although far more stable approach very common spacecraft dynamics graphic imaging, FHA struggles interpretational difficulties compared six degrees freedom analysis especially clinical context among medical professionals. 3D-motion has been used express motion kn kinematics cervical spine analyses (Osterbauer et al. 1992; Panjabi 1979; Woltring 1985). However, these type graphical representations does not allow for mathematical statistical comparison data lar dataset. It may cause establish reproducibility measures set normative cases. represents methodological focusing on andangle parameters an quantification behavior. METHODS the The algorithm this methods based first by Mozzi 1763 elaborated Ceccarelli (2000). helical characteristics extracted from R v defining matrix U that fulfils = RT - (Soderkvist 1993).RESULTS The input accuracy FHA-parameters shows linear relation between simulated error corresponding parameter following relationships parameters: a) 1 degree noise, 4 error; b) 2 mm c) d) e) (Figure 1). Further showed inversely proportional relationship steps position error. translation along was dependent steps. three increased proportionally level. can be determined calculating intersection points IHA (Instantaneous Axis) each planes perpendicular using (CH) technique. CH defined convex polygon area, which includes all plane (figure 2). also computed its distribution analyzed 2). CONCLUSION Input have demonstrated FHA-estimation accuracy. The represented hull angles relative FHA.