Design of a locomotion interface for gait simulation based on belt-driven parallel mechanisms

This paper presents the design of a locomotion interface for gait simulation and interaction with a virtual environment. The proposed mechanical interface is based on two planar two-degree-of-freedom belt-driven mechanisms which fully decouple the vertical and horizontal motion of two supporting footplates. Force sensors are mounted under the footplates in order to move the end effectors according to the user´s intentions. The user´s feet are rigidly attached to the footplates but a system of hinges allows an additional unactuated two-degree-of-freedom motion. A lag controller allows the user to move the end-effectors freely and a virtual floor based on a virtual spring and damper restrains the end-effectors´ movements so that the user experiences an intuitive contact with the ground. Finally, preliminary experiments are reported in order to demonstrate the capability of the locomotion interface for gait simulation.