“…The coefficient of friction (COF), which can be seen as a physics-based feature, has been used for many years as a principle feature for monitoring the condition of wet friction clutches (Matsuo & Saeki, 1997;Ost, Baets, & Degrieck, 2001;Maeda & Murakami, 2003;Li et al, 2003;Fei, Li, Qi, Fu, & Li, 2008). However, the use of the COF for clutch monitoring is possibly expensive and not easily implementable for real-life applications, due to the fact that at least two sensors are required to extract the COF, namely (i) a torque sensor and (ii) a force sensor, which are commonly difficult to install in a transmission (i.e.…”