Light curtain for detecting footfall instants during treadmill walking--an exploratory study.

Area of Science:

• Biomechanics
• Gait Analysis
• Human Movement Science

Background:

• Traditional methods for detecting footfall instants during treadmill walking include footswitches, instrumented insoles, and forceplates.
• These methods often require subject preparation or can be costly.
• Exploring novel, cost-effective, and less intrusive technologies is crucial for advancing gait analysis.

Purpose of the Study:

• To investigate the feasibility of using an optoelectronic light curtain for accurately detecting initial foot contact (FC) and toe-off (TO) instants during treadmill walking.
• To compare the performance of the light curtain system against established methods like footswitches and video analysis.
• To evaluate the potential advantages of the light curtain system in terms of cost, preparation, and signal characteristics.

Main Methods:

• An array of infrared light beams from a commercial light curtain was positioned 5 mm above a treadmill belt.
• Ten subjects walked at speeds of 0.5, 1.0, and 1.4 m/s while their gait was recorded by seven optoelectronic cameras.
• Footswitches on the heel and toe of the right foot served as the criterion measure for comparison with light curtain and video data.

Main Results:

• Foot contact (FC) instants from foot footswitches were within 10ms of the criterion.
• Both video and light curtain detected FC instants earlier than the criterion (by at least 30ms).
• Light curtain toe-off (TO) instants occurred significantly later than the criterion (>110ms) but exhibited the lowest variability.

Conclusions:

• The optoelectronic light curtain is a feasible tool for detecting footfall instants during treadmill walking.
• The system offers advantages such as low cost, no need for subject preparation, and real-time data acquisition.
• Further optimization of the light curtain setup is expected to enhance its accuracy for gait analysis.