:Taking Mitsubishi FX3U-48MR programmable controller as the control center, it drives the electric of the assembly line manipulator, and the servo driver drives the servo motor. The PLC-based assembly line manipulator electric drives the motion of the manipulator through the synchronous belt drive, which can realize the accurate position control of the manipulator. The proposed model will A Gaussian mixture distribution with heavy-tailed distribution characteristics is used as the model output likelihood function, and a parameterization method for the design of a full-dimensional PI observer with robust fault detection is established.