Abstract
Frustrated total internal reflection (FTIR) imaging was used to perform remote optical measurements of the forces/pressures exerted beneath shoes and feet during a number of different training activities including countermovement jumps, jogging and drop jumps. A single camera was used to simultaneously image two acrylic, FTIR waveguide imaging elements from below, at frame rates up to 200 frames per second. The images obtained using the camera were converted into pressure/force maps using a previously developed theory which combines the mechanics of contact of soft objects and the scattering of evanescent waves. The forces obtained from the optical measurements were shown to be in good agreement with measurements obtained from load cells placed beneath the FTIR imaging elements. The ability to produce accurate spatial maps of the force/pressure distribution beneath soft contacting objects such as feet and shoe outsoles at high frame rates has numerous potential applications in sports sciences and medicine.
Highlights
Measurement of the forces exerted beneath soft contacting objects such as shoes and human feet have a number of applications in sports science & engineering and medicine
Optical methods of force detection offer a potential low-cost alternative to electrically addressable pressure mats. One such technique involves the use of frustrated total internal reflection (FTIR) to measure the amount of light that is scattered in the regions of contact between a soft object and a hard transparent slab of material
The main panel in this figure demonstrates the high level of agreement between the forces obtained directly from the load cells and the forces obtained by summing the pressures obtained from the FTIR images
Summary
Measurement of the forces exerted beneath soft contacting objects such as shoes and human feet have a number of applications in sports science & engineering and medicine. Where P is the applied pressure, Io is the incident intensity on the waveguide surface, λ is the wavelength of light being scattered, Ap the area imaged by a pixel, no the refractive index (real part) of the contacting material and D Image processing techniques were used to analyse the response of each platform separately and to extract the pressure distributions beneath the contacting shoe outsoles and feet.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
