Human-in-the-loop tele-robotic systems (HiLTS) should provide their operators with the haptic sensory feedback needed to support dexterous manipulation akin to what is capable with the natural body. Unfortunately, providing robust kinesthetic haptic feedback often comes at the expense of control stability, which cannot be improved using simplified models of the operator's arm impedance that fail to take into account that individuals typically dynamically modulate this value throughout a given task. A primary objective of this research is to test the hypothesis that modulation of a kinesthetic haptic device's controlled and/or inherent impedance in accordance with the operator's impedance will improve the interface to and utility of HiLTS. Improving haptic feedback methodologies is an important area of research in HiLTS, haptic display, and human-machine interaction more generally. This work will provide a framework for relating haptic device impedance to user impedance and produce a set of generalizable principles for investigating all aspects of haptic device impedance on user impedance. Ultimately, project outcomes will lead to tele-robots that come closer to being embodied by their operators, thereby allowing for more robust and dexterous manipulation. The work will have broad impact on a variety of applications including surgical robotics, upper-limb prosthetics, and rehabilitation robotics. Educational and outreach activities will include conference workshops, a special topics course on HiLTS, lab tours, and summer activities for K-12 and underrepresented students.
Real-time measurements of the operator's arm impedance are possible using only knowledge of muscle activation and joint configuration, and further, these measures can be used as a basis for robotic control and stability. However, these methods have yet to gain widespread attention in the field of haptic display, where significant potential exists given the coupled nature of the human and device dynamics through a kinesthetic haptic device. Therefore, improving upon current methods of haptic display, especially for HiLTS, should involve active modulation of the operator's impedance through the haptic device, in a manner consistent with the modulations which occur through physical interaction with the natural limb. This research will contribute to both a theoretical and empirical understanding of the effect of haptic device impedance on the endpoint arm stiffness of a human user for the purpose of improved utility in HiLTS. The approach will involve: (1) identifying relationships between endpoint arm stiffness and environment impedance; (2) identifying relationships between endpoint arm stiffness and haptic device impedance; and (3) quantifying the effect of haptic device impedance modulation on endpoint arm stiffness in HiLTS.
