Approximately 20% of the world’s energy consumption is used to overcome
friction. Virtual prototyping, monitoring and diagnosis are topics of research to
realize the vision of smart tribology systems and increase efficiency and reliability. A significant challenge is the experimental techniques, because friction is not an intrinsic material property but a property of the system in which materials operate, and this gap between real and idealized test systems is a main research challenge in tribology today. Adaptive ultrasound reflectometry is a promising approach to perform in-situ non-invasive measurements of lubrication film thickness. Current adaptive schemes are based on estimation of individual frequencies in the incident wave spectrum, and varying excitation between frequencies complicates the thickness identification. This project aims at exploring multi-frequency adaptive filters based on a newly discovered reflection coefficient spectrum-diffusion equation.