To practically help those with limited mobility disorders, human exoskeletons need to be intelligent devices that not only guide the pilot along a particular gait but do so in a manner that is comfortable to the pilot and sensitive to pilot intent. This paper proposes sensing the user’s intent and then weighing gait tracking with amplifying the user’s input. To do so, this method utilizes a strain gauge to sense user intent, a Kalman filter to estimate the user’s input to the system, and an LQ-based controller that will weigh pure amplification of the user’s forces with tracking the ideal gait trajectory. This method is implemented in a simulation that showed the user’s input can be estimated under reasonable noise assumptions. This estimate is then supplied to the LQ-based controller with cost function weights on tracking, amplification, and motor input. Varying these weights changes the motor input torque profile to be smoother for the pilot’s comfort or better for tracking performance. These weights can be used to simply and quickly personalize the exoskeleton’s effect for each pilot. The LQ controller is found to yield a smooth torque profile to the user when compared to a PD trajectory tracking controller.
- Dynamic Systems and Control Division
Sensing User Input on a Human Exoskeleton Device
Perry, BW, & Kazerooni, H. "Sensing User Input on a Human Exoskeleton Device." Proceedings of the ASME 2014 Dynamic Systems and Control Conference. Volume 3: Industrial Applications; Modeling for Oil and Gas, Control and Validation, Estimation, and Control of Automotive Systems; Multi-Agent and Networked Systems; Control System Design; Physical Human-Robot Interaction; Rehabilitation Robotics; Sensing and Actuation for Control; Biomedical Systems; Time Delay Systems and Stability; Unmanned Ground and Surface Robotics; Vehicle Motion Controls; Vibration Analysis and Isolation; Vibration and Control for Energy Harvesting; Wind Energy. San Antonio, Texas, USA. October 22–24, 2014. V003T42A001. ASME. https://doi.org/10.1115/DSCC2014-5942
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