Optical measurement of contact forces using frustrated total internal reflection

Sharp, James S.; Poole, Stuart F.; Kleiman, Benjamin W.

Abstract

A simple device based on the principle of frustrated total internal reflection is used to image the regions of contact between rubber objects and a large-area perspex waveguide. Measurements of the intensity of light scattered at the interface are found to depend upon the magnitude of the applied force, the mechanical properties of the contacting material, and the roughness of the contacting objects. The intensity-force response is found to have the same functional dependence irrespective of the position on the waveguide surface, but to scale by an amount that is proportional to the local intensity of light incident on the perspex-object interface. Once this spatial variation in intensity is calibrated, the waveguide can be used to perform optical measurements of the forces/pressures exerted on the surface of the waveguide and to generate spatial maps of the pressure at frame rates up to 200 Hz. The resulting optical force platform is used to measure the time-dependent evolution of the pressure distribution beneath a foot and a sports shoe during a foot-strike event. A simple theory is developed to describe the light-scattering phenomenon and to explain the relationship between the scattered light intensity and the applied force.

Citation

Sharp, J. S., Poole, S. F., & Kleiman, B. W. (2018). Optical measurement of contact forces using frustrated total internal reflection. Physical Review Applied, 10(3), Article 034051. https://doi.org/10.1103/physrevapplied.10.034051

• Journal Article Type: Article
• Acceptance Date: Sep 24, 2018
• Online Publication Date: Sep 24, 2018
• Publication Date: Sep 24, 2018
• Deposit Date: Sep 25, 2018
• Publicly Available Date: Sep 26, 2018
• Journal: Physical Review Applied
• Electronic ISSN: 2331-7019
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 10
• Issue: 3
• Article Number: 034051
• DOI: https://doi.org/10.1103/physrevapplied.10.034051
• Public URL: https://nottingham-repository.worktribe.com/output/1130630
• Publisher URL: https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.10.034051
• Additional Information: ©2018 American Physical Society