Independent ankle motion control improves robotic balance simulator

We present a validation study for the effectiveness of an additional ankle-tilt platform to enhance somatosensory ankle feedback available to subjects actuating a 6-axis robotic balance simulator platform. To address this need, we have developed and integrated a device to permit independent manipulation of ankle rotation while the whole-body is actuated by the balance simulator. The addition of ankle rotation is shown to provide both quantitative and qualitative improvements to the balance simulation experience compared to when the ankle joint is referenced to the motion of the balance simulator. Eight out of ten subjects reported that balancing on the simulator with ankle motion required less conscious effort. This self-reported improvement corresponded to a 32% decrease in the mean-removed RMS amplitude for sway angle, demonstrating better balance control for subjects actuating the simulator. The new ankle-tilt platform enables examination of the contributions of ankle proprioception to the control of standing balance in human subjects.