Robust Proportional Integral-State Feedback with Disturbance Observer for 2-DOF Helicopter System. Al-Khwarizmi Engineering Journal, [S. l.], v. 20, n. 3, p. 11–19, 2024. DOI: 10.22153/kej.2024.04.001. Disponível em: https://www.alkej.uobaghdad.edu.iq/index.php/alkej/article/view/926. Acesso em: 30 apr. 2025.