Determination of the rotation axes of the artificial foot and ankle using a robotic gyroscopic mechanism

An important factor that makes walking of a biped robot or a human with a prosthetic ankle more similar to healthy human walking is that the ankle joint is modeled like the human ankle joint. A key factor in the real human ankle is its rotation axes. Therefore, determining the real orientation of the biped robot’s ankle rotation axes or prosthetic ankle becomes important in their calibration. In this study, a method based on data acquisition from the kinematic behavior of the artificial ankle using a robotic gyroscopic mechanism has been proposed. By performing this method, the orientation and position of the rotation axes were calculated at relatively high precision. These results were also assessed in practice by building an ankle mechanical model and gyroscopic mechanism. Results indicate that the error in calculating the orientation of the rotation axes is about 0.9°±0.4° for subtalar and 1.2°±0.6° for tibiotalar.