# A Performance Evaluation Approach for Satellite Attitude Control System in Tracking Mode
## 5 Evaluation Experiment and Analysis
### Comparative Analysis of Methods  
In order to verify the feasibility of the proposed method, based on the unified standardized data set in Section 5.1, in this paper, we designed a set of comparative experiments to evaluate the performance of the attitude control system in the attitude tracking mode of Earth observation satellites using the improved principal component grey target and two classical evaluation methods. The distance between superior and inferior solutions (TOPSIS) method is a method of evaluating system effectiveness by calculating the relative proximity between evaluation metrics and superior and inferior solutions, and the results accurately reflect the gaps between the assessment processes [30]. Fuzzy comprehensive evaluation (FCE) is a method based on fuzzy mathematical theory to make an overall evaluation of things or objects subject to a variety of factors, with clear results and systematic features [31]. The attitude tracking mode performance evaluation study was conducted using both the above methods, and here, the data of the sun-pointing mode is taken as an example, and the comprehensive evaluation results are shown in Tables 6 and 7:  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Improved Principal Component Grey Target** &  
According to the definition of performance indicators in Section 4.3 above, the performance evaluation results of the satellite attitude tracking mode were calculated by improving the principal component grey target, the good and bad distance solution method and the fuzzy comprehensive evaluation method. The results are shown in Table 8. In the calculation of deviation, attention should be paid to the trend of off-target distance, which is different from other methods. The smaller the off-target distance, the better the efficiency, while the greater the evaluation value, the better the efficiency. Before calculating the deviation, the off-target distance sorting result is replaced by an equivalent method. If the off-target distance of an attitude tracking process is set, it can be replaced to keep the trend of the evaluation results of the three methods consistent. From the evaluation results, the following conclusions can be drawn:  
(1) Of the three methods, comprising improved principal component grey target, TOPSIS and FCE, the maneuver process with the highest performance value was S14. The maneuver process with the worst performance of both the TOPSIS and FCE was S23, while the worst process was S24 in the evaluation results of the grey-target model. The differences between the maximum and minimum evaluation results of the three methods were 0.4362, 0.2965, 0.4131, respectively, and the difference found by the improved principal component grey target was the largest, indicating that the evaluation results had a larger span and could more effectively distinguish the advantages and disadvantages of different maneuvers. (2) The compatibility scores for the three methods were 0.9238, 0.9165 and 0.9124, respectively. The compatibility of the improved principal component grey target was the greatest, while the compatibility of TOPSIS was the least. The greater the compatibility, the closer and more representative the results of this evaluation method are to other methods, and the more accurate the evaluation results are. (3) Smaller deviation values mean that, compared with other methods, the evaluation results of the improved principal component grey target have less deviation, and the evaluation results are more reliable. The deviation of the four methods was less than 0.01, and the evaluation results are thus reliable. Among them, the deviation of TOPSIS was only 0.0041, the improved principal component grey target in this paper was second; the FCE had the largest deviation. In summary, the grey-target model based on the improved principal component presented in this paper had better performance under various analysis angles, and the comprehensive performance was the best.