Algorithm 1 Steps for the thermal image acquisition.

Step 1: Select one fault type from the ten health conditions. Step 2: Initialize the temperature of MFS system to the environment temperature (18.9 °C in this paper). Step 3: Conduct the thermal video acquisition under a constant speed of 3000 rpm. Step 4: Observe the highest temperature through the IRT camera (around the testing bearing). When the highest temperature reaches a relatively stable temperature (60 °C in this test), stop the thermal video acquisition. Step 5: Cool down the MFS system to the environment temperature. Step 6: Repeat the above steps for another fault type until the end of experiment. Step 7: Extract the thermal images from the thermal videos under each health condition.