[1] Kokotovic P., Khali H., and O’Reilly J., Perturbation methods in control: analysis and design. Singular Society for Industrial and Applied Mathematics, 1999.
[2] Tikhonov A., Systems of Differential Equations Containing Small Parameters in the Derivatives. Matematicheskii sbornik, , Vol. 73, No. 3, pp. 575–586, 1952.
[3] Vasil’eva A.B., Asymptotic Behaviour of Solutions to Certain Problems Involving Non-Linear Differential Equations Containing a Small Parameter Multiplying the Highest Derivatives. Russian Mathematical Surveys, Vol. 18, No. 3, pp. 13-18, 1963.
[4] Kelley H.J., Flight Path Optimization with Multiple Time Scales. Journal of Aircraft, Vol. 8, No. 4, pp. 238–240, 1971.
[5] Gajic Z., Optimal control of singularly perturbed linear systems and applications. CRC Press, 2001.
[6] Huaping L.I.U., Fuchun S.U.N., Kezhong H.E., and Zengqi S., Survey of Singularly Perturbed Control Systems: Theory and Applications. Control Theory and Applications, Vol. 20, No. 1, pp. 1–7, 2003.
[7] Naidu D.S., and Calise A.J., Singular Perturbations and Time Scales in Guidance and Control of Aerospace Systems. Journal of Guidance, Control and Dynamics, Vol. 24, No. 6, pp. 1057–1078, 2001.
[8] Spong M.W., Adaptive Control of Flexible Joint Manipulators. IEEE Control Systems Magazine, Vol. 13, No. 1, pp. 15–21, 1989.
[9] Ghorbel F., and Spong M.W., Stability analysis of adaptively controlled flexible joint manipulators. IEEE Conference on Decision and Control, pp. 2538–2544, 1990.
[10] Ding Y., and Xiao X., Speed control and resonance suppression of flexible joint system based on singular perturbation method and Kalman filter. Annual Conference of the IEEE Industrial Electronics Society, pp. 631–635, 2016.
[11] Han M.C., and Chen Y. H., Robust control design for uncertain flexible-joint manipulators. IEEE Conference on Decision and Control, pp. 611–616, 1993.
[12] Khan H., Bazaz M.A., and Nahvi S.A., Singular Perturbation Based Model Reduction of Power Electronic Circuits. IET Circuits, Devices & System, Vol. 13, No. 4, pp. 471–478, 2019.
[13] Lim J., and Shi P., Sliding Mode Control of Singularly Perturbed Systems and its Application in Quad-rotors. International Journal of Control, Vol. 92, No. 6, pp. 1325–1334, 2019.
[14] Vasquez R., and Krstic M., Thermal convection loop control by continuous backstepping and singular perturbations. American Control Conference, pp. 3882–3887, 2005.
[15] Rajagopalan P.K., and Naidu D.S., Singular Perturbation Method for Discrete Models of Continuous Systems in Optimal Control. IEE Proceedings D (Control Theory and Applications), Vol. 128, No. 4, pp. 142–148, 1981.
[16] Flores G., and Lozano R., Lyapunov-Based controller using singular perturbation theory: An application on a mini-UAV. American Control Conference, pp. 1596–1601, 2013.
[17] Kodra K., and Gajic Z., Optimal Control for a New Class of Singularly Perturbed Linear Systems. Automatica, Vol. 81, No.5, pp. 203–208, 2017.
[18] Long M., Su H., and Liu B., Second-Order Controllability of Two Time Scale Multi Agent Systems. Applied Mathematics and Computation, Vol.15, No.343, pp.299-313, 2019.
[19] Jing C., Xu H., and Jiang J., Practical Torque Tracking Control of Electro-hydraulic Load Simulator Using Singular Perturbation Theory. ISA transactions, 2020.
[20] Khalil H., Nonlinear systems, 3rd edition, Prentice Hall, 2002.
)