Grip force and force sharing in two different manipulation tasks with bottles

Area of Science:

• Biomechanics
• Human Factors Engineering
• Occupational Therapy

Background:

• Understanding how humans grip and manipulate objects is crucial for designing tools and assistive devices.
• Previous research has explored grip force but often in simplified or non-daily tasks.
• Investigating force sharing provides deeper insights into hand function during complex activities.

Purpose of the Study:

• To analyze grip force and force sharing during two activities of daily living: transporting and pouring bottles.
• To determine the influence of bottle features (shape, filling level) and task type on grip mechanics.
• To quantify the contribution of different hand/finger segments to overall grip force during these tasks.

Main Methods:

• 10 right-handed subjects performed transporting and pouring tasks with four bottle types at two filling levels.
• Hand instrumentation with eight wearable force sensors to measure grip force and force distribution.
• Analysis of grip force, load force, and force sharing ratios across different conditions.

Main Results:

• Grip force and force sharing varied significantly with bottle model and filling level.
• Increased filling level led to higher grip force, but grip-to-load force ratio was higher for lighter loads.
• Task type influenced force sharing (e.g., thumb/ring finger in pouring, palm/index in transport), but not mean grip force.

Conclusions:

• Bottle characteristics and filling levels significantly impact grip force and its distribution.
• Task demands (transporting vs. pouring) modulate how the hand distributes grip forces among its components.
• Findings offer insights for designing objects and rehabilitation strategies considering hand biomechanics in daily tasks.