@article{CRSIJ26000367,
                  author = {Ndifreke Akpan, Agorodi Dioni, Mbet-obong Akpan, Baruch Ekanem},
                  title = {Trajectory-Tracking Degradation Analysis of UAV Controllers under Payload Variation},
                  journal = {Cosmo Research and Science International Journal},
                  year = {2026},
                  volume = {2},
                  number = {2},
                  pages = {109-121},
                  issn = {3108-1584},
                  url = {https://cosmorsij.com/published/CRSIJ26000367.pdf},
                  abstract = {Payload variation is a primary source of performance degradation for unmanned aerial vehicle (UAV) trajectory-tracking systems, especially for manoeuvres involving payload pickup and delivery, or modular sensor deployment. In the present work, the degradation of UAV controllers’ trajectory tracking performance due to payload mass changes was investigated in MATLAB. A nominal PID controller for fixed-mass operation was evaluated against a robust controller with improved gain authority. A three-dimensional helical reference trajectory was used for simultaneously simulating the lateral and vertical dynamics. The performance of the controllers was tested in terms of root mean square (RMS) tracking error, overshoot, control effort, and velocity response characteristics. The simulation findings reveal that the RMS tracking error of the nominal controller grows from 0.18 m to 0.42 m as the payload increases from 0 kg to 1.0 kg, i.e., a performance loss of more than 130 %. The robust controller restricts the rise of RMS error to 0.16m from 0.09m, less than 25 % degradation. The nominal controller has an altitude overrun of 18 – 22 % in heavy cargo scenarios, while the robust controller always keeps the overshoot below 8 %. Moreover, the nominal controller requires a total control effort of about 20 N • s, whereas the robust controller requires about 35 N • s. This amounts to a reduction of more than 20 %. The results demonstrate that nominal UAV controllers are quite sensitive to payload variations, and the performance deteriorates dramatically with the payload rise. Robust control systems can greatly improve the trajectory-tracking accuracy, stability, and energy efficiency. Thus, the present work provides a realistic and reproducible methodology to test and optimize the robustness of the payload in UAV trajectory-tracking systems.},
                  keywords = {Unmanned Aerial Vehicle (UAV), Trajectory Tracking Control, Payload Variation, Performance Degradation Analysis, Dynamic Modelling},
                  month = {September}
        }