Human Force Discrimination during Active Arm Motion for Force Feedback Design

Shams Feyzabadi, Sirko Straube, Michele Folgheraiter, Elsa Andrea Kirchner, Su-Kyoung Kim, Jan Albiez
In IEEE Transactions on Haptics, oA, volume 6, number 3, pages 309-319, Nov/2013.

Abstract

The goal of this study was to analyze the human ability of external force discrimination while actively moving the arm. With the approach presented here, we give an overview for the whole arm of the just-noticeable differences (JNDs) for controlled movements separately executed for the wrist, elbow, and shoulder joints. The work was originally motivated in the design phase of the actuation system of a wearable exoskeleton, which is used in a teleoperation scenario where force feedback should be provided to the subject. The amount of this force feedback has to be calibrated according to the human force discrimination abilities. In the experiments presented here, 10 subjects performed a series of movements facing an opposing force from a commercial haptic interface. Force changes had to be detected in a two-alternative forced choice task. For each of the three joints tested, perceptual thresholds were measured as absolute thresholds (no reference force) and three JNDs corresponding to three reference forces chosen. For this, we used the outcome of the QUEST procedure after 70 trials. Using these four measurements we computed the Weber fraction. Our results demonstrate that different Weber fractions can be measured with respect to the joint. These were 0.11, 0.13, and 0.08 for wrist, elbow, and shoulder, respectively. It is discussed that force perception may be affected by the number of muscles involved and the reproducibility of the movement itself. The minimum perceivable force, on average, was 0.04 N for all three joints.

Keywords

Perception, psychophysics, biorobotics, human factors, wearable computers

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@article{Feyzabadi2013Human,
  author    = {Feyzabadi, Shams and Straube, Sirko and Folgheraiter, Michele and Kirchner, Elsa
               Andrea and Kim, Su-Kyoung and Albiez, Jan},
  title     = {Human Force Discrimination during Active Arm Motion for Force Feedback Design},
  journal   = {{IEEE} Transactions on Haptics},
  volume    = {6},
  number    = {3},
  pages     = {309--319},
  month     = nov,
  year      = {2013},
  url       = {https://robotik.dfki-bremen.de/en/research/publications/6949}
}
Download (.bib) 
TY  - JOUR
AU  - Feyzabadi, Shams
AU  - Straube, Sirko
AU  - Folgheraiter, Michele
AU  - Kirchner, Elsa Andrea
AU  - Kim, Su-Kyoung
AU  - Albiez, Jan
TI  - Human Force Discrimination during Active Arm Motion for Force Feedback Design
T2  - IEEE Transactions on Haptics
VL  - 6
IS  - 3
SP  - 309
EP  - 319
PY  - 2013
DA  - 2013/11//
AB  - The goal of this study was to analyze the human ability of external force discrimination while actively moving the arm. With the approach presented here, we give an overview for the whole arm of the just-noticeable differences (JNDs) for controlled movements separately executed for the wrist, elbow, and shoulder joints. The work was originally motivated in the design phase of the actuation system of a wearable exoskeleton, which is used in a teleoperation scenario where force feedback should be provided to the subject. The amount of this force feedback has to be calibrated according to the human force discrimination abilities. In the experiments presented here, 10 subjects performed a series of movements facing an opposing force from a commercial haptic interface. Force changes had to be detected in a two-alternative forced choice task. For each of the three joints tested, perceptual thresholds were measured as absolute thresholds (no reference force) and three JNDs corresponding to three reference forces chosen. For this, we used the outcome of the QUEST procedure after 70 trials. Using these four measurements we computed the Weber fraction. Our results demonstrate that different Weber fractions can be measured with respect to the joint. These were 0.11, 0.13, and 0.08 for wrist, elbow, and shoulder, respectively. It is discussed that force perception may be affected by the number of muscles involved and the reproducibility of the movement itself. The minimum perceivable force, on average, was 0.04 N for all three joints.
KW  - Perception
KW  - psychophysics
KW  - biorobotics
KW  - human factors
KW  - wearable computers
UR  - https://robotik.dfki-bremen.de/en/research/publications/6949
LA  - eng
ER  -
Download (.ris) 
Feyzabadi, S., Straube, S., Folgheraiter, M., Kirchner, E. A., Kim, S.-K., & Albiez, J. (2013). Human Force Discrimination during Active Arm Motion for Force Feedback Design. IEEE Transactions on Haptics, 6(3), 309–319. https://robotik.dfki-bremen.de/en/research/publications/6949


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