Meeting Abstract
Animals use feedback to correct for deviations from an ideal motion to improve their accuracy when performing tasks, whether it’s plucking a fruit from a tree or maintaining balance while standing from a resting position. Correcting for deviations from an ideal motion can be essential to survival, especially in elderly humans who are often severely injured while failing to successfully perform sit-to-stand (STS) motions. One simple strategy that can be theoretically used to correct trajectories is linear state feedback (LSF), in which linear gains are placed on errors from an ideal trajectory and added back into the motion’s nominal control law. To determine whether humans use the LSF strategy to correct their motion, we observed human response to perturbation while performing STS motions. Eleven human subjects were perturbed by pulling them either forward or backward from the waist via motor-driven cables. Perturbations of up to 124 N of force were applied at various times between seat-off and standing. Human motion was quantified using motion capture data, and was modeled as an inverted pendulum. Each subject’s perturbed trajectory was compared to their own unperturbed trajectories. We found that corrective movements in response to perturbation fit the LSF strategy. By quantifying the magnitude of perturbation a human can withstand and how effectively they can perform the LSF strategy, this type of perturbative experiment has the potential to identify individuals at risk for debilitating injury. Since the response to perturbation is commonly measured in animal experiments, this approach enables direct comparison between human and other animal control strategies.
