Instant center of rotation estimation using the Reuleaux technique and a Lateral Extrapolation technique

Area of Science:

• Biomechanics
• Robotics
• Kinematics

Background:

• Estimating planar instant centers of rotation (ICRs) is crucial for analyzing motion.
• The Reuleaux technique is a common method for pole measurement but can introduce significant errors.
• Errors increase with larger rotation angles, limiting its application in certain scenarios.

Purpose of the Study:

• To investigate errors in the Reuleaux technique for estimating ICRs.
• To introduce and evaluate a new Lateral Extrapolation technique for improving ICR estimation accuracy.
• To assess the potential clinical applications of enhanced ICR measurement.

Main Methods:

• Development of a mathematical model simulating a rolling wheel.
• Application of the Reuleaux technique to pole data from the model.
• Implementation and testing of the Lateral Extrapolation technique on the same data.
• Validation of the extrapolation technique with models of joints exhibiting slip and roll.

Main Results:

• The Reuleaux technique produced substantial errors (e.g., 3.96cm at 45° roll) when estimating ICRs.
• The Lateral Extrapolation technique significantly reduced these errors (e.g., to 0.52cm at 45° roll).
• Accuracy improvements were over sevenfold for a 45° roll and over twenty-fivefold for a 12° roll.

Conclusions:

• The Lateral Extrapolation technique offers a substantial improvement in accuracy for estimating ICRs compared to the Reuleaux technique.
• This enhanced accuracy has potential applications in clinical settings for detecting joint pathologies through ICR pathway analysis.
• The validated technique shows promise for analyzing complex joint movements involving both slip and roll.