# A Performance Evaluation Approach for Satellite Attitude Control System in Tracking Mode
## 2 Problem Description  
### Satellite Attitude Control System Tracking Model  
In the tracking mode, the satellite attitude control system continuously collects and analyzes the positional and directional information of target objects. Based on the information, it guides the satellite direction and attitude adjustments to ensure the stable operation of satellites in an ever-changing environment, which can enable satellites to achieve high-precision positioning and orientation control. This mode is applicable across various satellite domains, including communication, navigation, meteorology, military, and scientific research.  
Attitude tracking keeps the satellite attitude in a given orientation and maintains attitude stabilization such as orientation to the sun and orientation to the earth. Typically, the satellite will enter the attitude tracking mode after performing attitude maneuvers to complete the corresponding space observation tasks. This mode operates over an extended period, often lasting several hours or even days. Taking the sun-pointing mode under the tracking mode of the satellite attitude control system as an example, in the sun- pointing mode, in order to enhance the efficiency of the solar panels and maintain the best angle of solar illumination, the satellite attitude control system needs to realize the accurate pointing control of the sun. The schematic diagram of the sun-pointing mode is shown in Figure 1.  
Oriented to the mission requirements of the tracking mode, the control performance indicators of the satellite attitude control system tracking mode should be able to meet the characteristics of speed, accuracy and stability. Specifically, the following aspects can be considered:  
(1) Rapid control response: In the process of a satellite tracking targets, the control system needs to exhibit a swift response rate to promptly adjust the attitude to the target state, thus ensuring the tracking accuracy and stability of the satellite. Therefore, the attitude control response time can be selected as a performance evaluation indicator.  
(2) High control accuracy: The control accuracy under tracking mode requires the satellite attitude control system to have a certain degree of robustness and anti-interference ability to cope with the influence of external environmental changes and interference. The system should be able to effectively recognize and mitigate interference to maintain good control accuracy. Therefore, the attitude pointing accuracy can be selected as a performance evaluation indicator.  
(3) Control stability: Under the tracking mode, the satellite attitude control system should have good stability and be able to maintain the stability and accuracy of the satellite attitude during long-time operation, so as to fulfill the demands of tracking targets. Therefore, the pointing stability can be selected as a performance evaluation indicator.  
(4) Low energy consumption: The satellite attitude control system should adopt energy consumption optimization strategies under tracking mode to minimize energy consumption and improve the energy efficiency of the system, and energy-saving strategies can be adopted, such as reducing the power output of the controller and optimizing the controller's working mode, in order to prolong the satellite's lifespan. Therefore, the attitude control energy consumption can be selected as a performance evaluation indicator.