## 1 Introduction  
With the increasing development of UAV platforms, the application proportion of photoelectric pods is gradually increasing in military, police, and civil fields. Especially in aspects such as resource exploration, urban patrol, and forest fire prevention. Additionally, with the improvement of the load-carrying capacity of UAVs, the functions that photoelectric pods can have are becoming more and more diverse, including visible light/infrared reconnaissance, laser ranging/guidance, and other aspects. The photoelectric pod has developed rapidly in the past 30 years, especially in reconnaissance alarm, target indication, control aiming and navigation tracking [1, 2]. The main task of the photoelectric pod controller is to isolate the external disturbance of the platform [3]. It maintains the stability of the line of sight axis in the inertial space, and realizes capturing targets and the tracking of the motorized targets. As the internal loop of the system, the stable loop is an important part of its control system. Its control performance directly determines the tracking performance of the photoelectric pod. It has the function of isolating the carrier disturbance, compensating for the friction moment and eliminating the influence of various process noise, and then realizing the function of stabilizing and tracking [4]. In the actual process, the working environment of the photoelectric pod is harsh. The attitude change in the carrier, high frequency vibration, and wind resistance torque during flight will cause visual axis pointing instability, affecting the imaging of the system [5, 6]. The Active Disturbance Rejection Controller (ADRC) is a new modern control method, which follows the increasing progress of computer control technology [7]. It was initiated by Professor [PERSON] in the late 1980s. ADRC uses the nonlinear discretization of the classical PID control theory, and finally evolves into a relatively mature control method, which has the advantages of a wide application and high control accuracy and modularity. ADRC has a more significant control ability, especially in a control environment with great interference or strict requirements on the control speed and control accuracy, and has achieved remarkable results in servo control mechanisms, ship control systems, precision machine tool processing, aircraft control, etc. [8]. In 2002, the spacecraft power generation device successfully solved the voltage control problem by using ADRC. In September 2004, NASA adopted ADRC to control Micro-Slide nanoscale displacement and achieved the expected control effects. In 2004, the jet engine control experiment using ADRC achieved exciting results. The physical experiments and field applications of ADRC in different engineering fields show that it will be able to replace the traditional PID in the form of a digital controller. [PERSON] [9] developed a concise method to determine the parameters of the ADRC linear expansion state observer with the bandwidth. [PERSON] [10] conducted related research on the application of the ADRC in strong coupling, nonlinear, and large delay thermal objects, such as ball mill, and proved that it has good extension value in a multivariable decoupling control system. [PERSON] [11] applied the self-disturbance control controller to the ship heading control and summarized the ADRC parameter setting method on the basis of simulation experiments. [PERSON] [12] explored the application of the ADRC in missile attitude control, and the conclusion shows that it has a good application prospect in missile control system. In terms of the photoelectric stability system, [PERSON] applied the ADRC to compensate for the interference of wind resistance in the control design of a large aperture photoelectric telescope. The simulation results show that the control effects of ADRC are better than that of PID [13]. [PERSON] [14] conducted a simulation comparative test on ADRC and PID controller with a certain type of airborne photoelectric reconnaissance platform as the control object.