Load Carriage Device for Studying Medial-Lateral Stability of Walking: Design and Performance Evaluation

When walking, the trunk not only oscillates in the vertical direction, but also in the medial-lateral direction. We developed a novel backpack that uses the medial-lateral oscillations of the trunk as input motion to drive medial-lateral oscillations of weight carried in a modified backpack. We use a combination of spring and damping elements to control mass motion, resulting in the ability to prescribe a variety of mass oscillation amplitudes and phase angles. We propose the device as a platform that can be used to study medial-lateral stability during walking. In particular, if the body's ability to predict medial-lateral centre-of-mass state is affected by an oscillating external mass. In this paper, we present the design, model, and model evaluation of our novel load carriage device. During testing, our model was able to predict the oscillation dynamics of the carried mass while walking: demonstrating its capability to create a variety of load carriage scenarios for the user.