Doctoral Dissertations

Keywords and Phrases

arm stiffness; impedance; motor communication; overground; physical human-robot interaction; robot


"The overground interactive robots are potentially beneficial for humans in various areas, such as overground rehabilitation therapies and robotic interactive assistance. However, it is unclear what the expectations and challenges are for a robot to be physically interactive with a human during overground tasks, such as a robot helping an older adult walk. To develop such a robot, one must first build a clear understanding of how the human motor intent is communicated when interacting with another agent. Specifically, how do humans understand the leader’s intention when being led?

Based on previous works, we hypothesized that humans modulate their arm impedance to measure interaction forces and motion sensitively. To study and test this hypothesis, it was required to measure the arm impedance during the human-agent interaction as precisely as possible and correlate the pattern of change in arm impedance with the pattern of fluctuation of interaction forces and motion. Because the existing interactive robots were not suitable for studying human arm impedance during overground interactive tasks, a new experimental robot -- Ophrie -- was developed that is capable of performing overground interaction with a human and can also measure arm impedance simultaneously.

Enabled by Ophire, an experiment was designed and conducted where the blindfolded human participants were asked to follow Ophire by holding its interactive handle. Arm stiffness was measured at the moment when A: the participants were compelled to listen to (or sense) haptic information from the robot, and B: when they were not compelled to. We found out that the arm stiffness of the participants at A was significantly lower compared to B. This outcome suggests that, as we hypothesized, the human nervous system modulates the arm stiffness to facilitate effective motor communication during overground physical interaction"--Abstract, p. iv


Song, Yun Seong

Committee Member(s)

Midha, A. (Ashok)
Burns, Devin D.
Bristow, Douglas A.
Krishnamurthy, K.


Mechanical and Aerospace Engineering

Degree Name

Ph. D. in Mechanical Engineering


Missouri University of Science and Technology

Publication Date

Spring 2022


xiii, 162 pages

Note about bibliography

Includes_bibliographical_references_(pages 154-161)


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Document Type

Dissertation - Open Access

File Type




Thesis Number

T 12231