An instrumented cylinder measuring pinch force and orientation

Area of Science:

• Biomechanics
• Human Factors Engineering
• Rehabilitation Technology

Background:

• Describes a novel cylinder apparatus designed for simultaneous measurement of hand pinch force and opposition axis.
• Highlights the need for precise tools to evaluate grip function in various populations.

Purpose of the Study:

• To introduce and validate a new cylinder-based apparatus for quantifying pinch force magnitude and opposition axis.
• To assess the reliability and precision of the developed measurement system.

Main Methods:

• Utilized a two-half-cylinder design connected via a 6-axis force/torque sensor to measure 3D forces and moments.
• Developed custom software to calculate the opposition axis angle and pinch force location.
• Validated the apparatus using calibrated weights and analyzed measurement dispersion and angular errors.

Main Results:

• Demonstrated high reliability with force position accuracy within 1 mm and angular errors less than 2 degrees.
• Evaluated pinch force and opposition axis in healthy subjects, showing controlled grip force across different hand orientations.
• Confirmed the apparatus's precision across various measurement sites on the cylinder.

Conclusions:

• The developed cylinder is a valid, reliable, and precise instrument for measuring opposition axis and grip force.
• The apparatus shows potential utility for evaluating grip function in both healthy individuals and those with pathological conditions.
• This tool can aid in objective assessment and understanding of hand function.