Characterizing the Coefficient of Friction Between a Capsule Robot and the Colon.

Area of Science:

• Biomedical Engineering
• Robotics
• Tribology

Background:

• Capsule robots (CRs) offer a minimally-invasive alternative to colonoscopy.
• Accurate prediction of friction forces is crucial for CR development and control.
• A quantitative understanding of the coefficient of friction (COF) in the colon is lacking.

Purpose of the Study:

• To determine a quantitative coefficient of friction (COF) equation for capsule robots (CRs) operating in the colon.
• To establish an equation relating COF to contact pressure, hoop strain, and sliding velocity.
• To enable improved prediction of traction force and locomotion resistance for CRs.

Main Methods:

• Measured COFs for PDMS, white ABS, and transparent ABS materials under 144 different friction conditions.
• Investigated the influence of contact pressure, hoop strain, and sliding velocity on COF.
• Developed a general COF equation with eight fitted constants based on experimental data.

Main Results:

• Developed a COF equation with high determination coefficients (up to 0.9822) for the tested materials.
• The equation accurately predicted traction force and locomotion resistance for a crawler CR.
• Demonstrated the influence of pressure, strain, and velocity on CR material friction.

Conclusions:

• The derived COF equation provides accurate friction force predictions for CRs.
• This research enables better force and locomotion control for capsule robots in the colon.
• The findings are significant for advancing the development and application of colon CRs.