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Updated: Jul 13, 2026
09:36
Measurement of Spatial Stability in Precision Grip
Published on: June 4, 2020
Adjustments to local friction in multifinger prehension
Tomoko Aoki1, Mark L Latash, Vladimir M Zatsiorsky
1Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Japan. aoki@pu-kumamoto.ac.jp
Journal of Motor Behavior
|August 1, 2007
Summary
Surface friction significantly impacts how fingers grip objects. Adjusting friction on individual digits alters grip force distribution and stability, crucial for understanding human manipulation.
Area of Science:
- Biomechanics
- Human-Computer Interaction
- Robotics
Background:
- Understanding digit forces is crucial for grasping.
- Surface friction at the digit-object interface influences grip control.
- Previous research has not fully explored friction's independent effects on each digit.
Purpose of the Study:
- To investigate the effects of surface friction on digit forces and moments during static grasping.
- To analyze how varying friction levels (low-friction contact and high-friction contact) across individual digits impacts grasp stability.
Main Methods:
- 12 participants performed a 5-digit static grasp of an object.
- Surface friction was manipulated independently for each digit using rayon (low-friction) and sandpaper (high-friction) in 32 combinations.
- Digit forces and moments were measured.
Main Results:
- Normal forces increased when the thumb was at low-friction contact or when more fingers were at low-friction contact.
- Thumb tangential force decreased with low-friction contact.
- Virtual finger (VF) tangential force decreased as the number of low-friction digits increased.
Conclusions:
- Grasp force coordination is explained by the interplay between local friction responses and necessary synergistic actions for equilibrium.
- Friction's role at the digit-object interface is a key factor in modulating grasp forces.
- Findings have implications for designing more adaptable robotic grippers and understanding human motor control.
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01:27Types of Friction Problems
Friction is an essential concept in physics, engineering, and everyday life. It is the force that opposes the relative motion or tendency of such motion between two surfaces in contact. One of the most common types of friction encountered in various applications is dry friction. Dry friction problems can be broadly categorized into three types, each with unique characteristics and challenges.
The first type of dry friction problem involves situations where there is no apparent impending motion.
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01:30Dry Friction
Dry friction occurs between two solid surfaces in contact as they attempt to move relative to one another. In daily life, dry friction is encountered in various forms, such as when walking on the ground, sliding an object across a table, or rubbing hands together. Despite its ubiquity, the underlying mechanisms behind dry friction are not readily visible.
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