Name
Title | ||
|---|---|---|
Complex Stiffness Model Of Physical Human-Robot Interaction: Implications For Control Of Performance Augmentation Exoskeletons |
Abstract | ||
|---|---|---|
Human joint dynamic stiffness plays an important role in the stability of performance augmentation exoskeletons. In this paper, we consider a new frequency domain model of the human joint dynamics which features a complex value stiffness. This complex stiffness consists of a real stiffness and a hysteretic damping. We use it to explain the dynamic behaviors of the human connected to the exoskeleton, in particular the observed non-zero low frequency phase shift and the near constant damping ratio of the resonance as stiffness and inertia vary. We validate this concept with an elbow-joint exoskeleton testbed (attached to a subject) by experimentally varying joint stiffness behavior, exoskeleton inertia, and the strength augmentation gain. We compare three different models of elbow-joint dynamic stiffness: a model with real stiffness, viscous damping and inertia; a model with complex stiffness and inertia; and a model combining the previous two models. Our results show that the hysteretic damping term improves modeling accuracy (via a statistical F-test). Moreover, this term contributes more to model accuracy than the viscous damping term. In addition, we experimentally observe a linear relationship between the hysteretic damping and the real part of the stiffness which allows us to simplify the complex stiffness model down to a 1-parameter system. Ultimately, we design a fractional order controller to demonstrate how human hysteretic damping behavior can be exploited to improve strength amplification performance while maintaining stability. |
Year | DOI | Venue |
|---|---|---|
2019 | 10.1109/IROS40897.2019.8968005 | 2019 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IROS) |
Field | DocType | Volume |
Frequency domain,Joint stiffness,Control theory,Computer science,Stiffness,Control theory,Hysteresis,Damping ratio,Control engineering,Exoskeleton,Inertia | Conference | abs/1903.00704 |
ISSN | Citations | PageRank |
2153-0858 | 0 | 0.34 |
References | Authors | |
6 | 4 | |
Name | Order | Citations | PageRank |
|---|---|---|---|
| Binghan He | 1 | 1 | 1.40 |
| Huang Huang | 2 | 0 | 0.68 |
| Gray C. Thomas | 3 | 48 | 6.31 |
| Luis Sentis | 4 | 574 | 59.74 |