Submitted by Dylan Losey on
Title | Effects of Discretization on the K-Width of Series Elastic Actuators |
Publication Type | Conference Proceedings |
Year of Conference | 2017 |
Authors | Losey, DP, O'Malley, MK |
Conference Name | International Conference on Robotics and Automation (ICRA) |
Pagination | 421-426 |
Date Published | 05/2017 |
Publisher | IEEE |
Conference Location | Singapore |
ISBN Number | 978-1-5090-4633-1 |
ISBN | 978-1-5090-4633-1 |
Abstract | Rigid haptic devices enable humans to physically interact with virtual environments, and the range of impedances that can be safely rendered using these rigid devices is quantified by the Z-Width metric. Series elastic actuators (SEAs) similarly modulate the impedance felt by the human operator when interacting with a robotic device, and, in particular, the robot's perceived stiffness can be controlled by changing the elastic element's equilibrium position. In this paper, we explore the K-Width of SEAs, while specifically focusing on how discretization inherent in the computer-control architecture affects the system's passivity. We first propose a hybrid model for a single degree-of-freedom (DoF) SEA based on prior hybrid models for rigid haptic systems. Next, we derive a closed-form bound on the K-Width of SEAs that is a generalization of known constraints for both rigid haptic systems and continuous time SEA models. This bound is first derived under a continuous time approximation, and is then numerically supported with discrete time analysis. Finally, experimental results validate our finding that large pure masses are the most destabilizing operator in human-SEA interactions, and demonstrate the accuracy of our theoretical K-Width bound. |
URL | http://ieeexplore.ieee.org/abstract/document/7989054/ |
DOI | 10.1109/ICRA.2017.7989054 |