Position-based Treadmill Drive with Wire Traction for Experience of Level Ground Walking from Gait Acceleration State to Steady State

A treadmill system has a large potential to provide humans with an augmented walking experience in real-life without a spatial limitation. However, a treadmill gait is different from walking on level ground. In previous studies, the adaptive belt speed control of a treadmill was developed to achieve a self-paced walking for making the users' treadmill gait similar to their level ground gait. Such studies have focused on steady-state walking and regulating the user's position on the treadmill. A normal gait can be divided into an acceleration state after gait initiation, a steady state, and a deceleration state for stopping. The objective of this study is to develop a treadmill system with a wire tension application enabling a human to experience a similar gait to a level ground gait during the transition phase from an acceleration state to a steady state. We developed a treadmill 4 m long x 1 m wide. To allow a user to move on the treadmill during the gait acceleration phase, an insensitive zone where a user can move without the treadmill belt drive was set. In addition, the treadmill was equipped with a wire traction system to apply a traction force canceling the effect of the belt floor acceleration of the treadmill when the belt speed of the treadmill changes. Through an experiment with six participants, the proposed treadmill system allowed the users to move in an acceleration state with the same head acceleration pattern as with level ground walking and cancel the inertial effect with the wire traction, which enabled the users to transition to a steady state from an acceleration state.