AVIC Chengdu Aircraft Design and Research Institute 1 article published in JoVE Engineering Design and Application of a Fault Detection Method Based on Adaptive Filters and Rotational Speed Estimation for an Electro-Hydrostatic Actuator Yongling Fu1,2, Yuxuan Ma1,2, Zhenyu Gou3, Tuanhui Guo1,2, Junhao Liu1,2, Jiangao Zhao2,4 1School of Mechanical Engineering and Automation, Beihang University, 2Laboratory of Aerospace Servo Actuation and Transmission, Beihang University, 3AVIC Chengdu Aircraft Design & Research Institute, 4Research Institute for Frontier Science, Beihang University In this paper, an adaptive filter based on a normalized least mean square (NLMS) algorithm and a rotational speed estimation method are introduced to detect the electrical and hydraulic faults of the electro-hydrostatic actuator (EHA). The efficacy and feasibility of the aforementioned methods are verified through simulations and experiments.