Functional Specifications Summary:
The design of the lower limb model consists of three joints, the hip, knee, and ankle, and three members, the femur, tibia, and foot. To closely model the three degreesoffreedom in the hip, the three individual degreesoffreedom have been separated into three joints with a single degreeoffreedom. This consists of a hybrid of the rollpitchyaw and rollpitchroll configurations used in robotics. The first roll models hip extension and flexion, the pitch models abduction and adduction, and the yaw or roll models hip rotation. Similarly, the ankle will be separated into two singledegreeoffreedom joints. One joint with a single degreeoffreedom will perform plantarflexion and dorsiflexion. Another joint performs inversion and eversion. To make the model anatomically correct, these two joints are separated by a distance of one inch, with the plantarflexion and dorsiflexion joint on top.
For more detail, read the entire document
Section 4 - Functional Specifications (.pdf)
Authored by Brad Hansen and Chad Taylor