in the literature) by mean rotational values less than or equal to 6.180 and mean
translational values less than or equal to 1.05 cm (Appendix E). When compared to the
synthetic data with noise, the outer-level fitness history of the multi-cycle experimental
data optimization converged at approximately the same rate and resulted in an improved
final solution for both the ankle and the hip (Figure 4-2). On the contrary, the higher
objective function values for the knee are evidence of the inability of the fixed pin joint to
represent the screw-home motion (Blankevoort et al., 1988) of the multi-cycle
experimental knee data. The multi-cycle hip, knee, and ankle optimizations terminated
with a mean wall clock time of 35.94 hours.
For one-half-cycle experimental motions, the mean marker distance error of the
optimal hip, knee, and ankle solutions was 0.30 cm for the first half and 0.30 cm for the
second half (Table 4-3). The fitness of both the ankle and the hip were comparable to the
multi-cycle joint motion results. However, the knee fitness values were improved due to
the reduced influence (i.e., 1 time frame of data as opposed to 9) of the screw-home
motion of the knee. For each joint complex, the optimum model parameters improved
upon the nominal parameter data (or values found in the literature) by mean rotational
values less than or equal to 11.080 and mean translational values less than or equal to
2.78 cm (Appendix F, Appendix G). In addition, the optimum model parameters for
one-half-cycle motion differed from those for the multi-cycle motion by mean rotational
values less than or equal to 15.770 and mean translational values less than or equal to
2.95 cm (Appendix H, Appendix I). The one-half-cycle hip, knee, and ankle
optimizations terminated with a mean wall clock time of 11.77 hours.