2016 Volume 5 Issue 2 Pages 47-52
The theory of functionally different effective muscles allows for detailed measurement of the muscular strength of limbs by separating mono-articular muscles and bi-articular muscles. The theory represents the output force distribution (OFD) at the end of a limb as a hexagon whose opposite sides are parallel and the same length. Because the OFD is divided into independent muscular strengths, it must be measured accurately. The OFD can be drawn from measurements of five of the six sides. This paper proposes a method to draw the OFD from measurements of all six sides. Because the measurement does not satisfy the characteristics of the OFD, an optimization problem is proposed for minimizing the distance from the original measurement while satisfying the characteristics. These two drawing methods of OFD were applied to the lower limbs of three subjects for three different postures. Because the error of the five-side measurement method is dependent on the estimated side and posture of lower limbs, the estimated side that realizes the smallest error of the OFD for a given posture can be determined from geometrical analysis. The OFD error of the optimization method was about half that of the five-side measurement method.