To determine fault type and location quickly

mathematical model for serial manipulator is established and the motion is controlled by backstepping controller. Common fault types are analyzed and corresponding fault models are built. Considering the most serious status: actuator and sensor locking failure（ the two faults have the same external manifestations）

residual observer is established by using feedback information and robotic arm model. The failure is determined by velocity residuals. The simulation platform is established by adding fault signal to normal condition. The experimental result shows that the method can identify the fault type and position of manipulator joints in two control periods.