Abstract—This paper develops a new strategy for robustfault tolerant control (FTC) of robot manipulators usingan adaptive fuzzy integral sliding mode control and a disturbanceobserver (DO). First, an integral sliding modecontrol (ISMC) is developed for the FTC system. The majorfeatures of the approach are discussed. Then, to enhanceperformance of the system, a fuzzy logic system (FLS)approximation and a DO are introduced to approximatethe unknown nonlinear terms, which include the modeluncertainty and fault components, and estimates the compoundeddisturbance, respectively, and then integrated intothe ISMC. Next, a switching term based on an adaptive twolayersuper-twisting algorithm is designed to compensatethe disturbance estimated error and guarantee stability andconvergence of the whole system. The nominal controllerof the ISMC is reconstructed using backstepping controltechnique to achieve the stability for the nominal systembased on Lyapunov criteria. The computer simulation resultsdemonstrate the effectiveness of the proposed approach.Index Terms—Control of robots, backsepping control,fault tolerant control, integral sliding mode control, adaptiveneural network, disturbance observer