Robust Control for a 3DOF Articulated Robotic Manipulator Joint Torque under Uncertainties

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Chukwudi Emmanuel Agbaraji
Uchenna Henrietta Udeani
Hyacinth Chibueze Inyiama
Christiana Chikodi Okezie


This research work emphasizes on design of a robust control for a 3DOF robotic manipulator under uncertainties. The plant model was achieved using the independent joint method and the uncertainty problem was addressed by designing a robust controller using H-Infinity synthesis which was compared with PID. This was achieved with algorithms implemented in MATLAB. The H-Infinity controller recorded 0dB, while PID controller recorded 0.117dB and 0.061dB for joints I and II respectively in Complementary Sensitivity (T) graph at low frequencies. H-Infinity controller achieved better disturbance rejection characteristics with sensitivity (S) graph recording peak sensitivity of 0.817dB and 1.79dB at joints I and II respectively than PID controller which achieved 3dB and 1.86dB at joints I and II respectively. H-Infinity controller achieved better noise rejection characteristics with T graph recording lower gains at joints I and II respectively at high frequencies than PID controller which recorded higher gains at joints I and II respectively. Thus, it was concluded that the H-Infinity controller achieved better performance and stability robustness characteristics for the joint torque control than the PID.

H-Infinity synthesis, joint torque control, PID, robotic manipulator, robust control, uncertainty.

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How to Cite
Emmanuel Agbaraji, C., Henrietta Udeani, U., Chibueze Inyiama, H., & Chikodi Okezie, C. (2020). Robust Control for a 3DOF Articulated Robotic Manipulator Joint Torque under Uncertainties. Journal of Engineering Research and Reports, 9(4), 1-13.
Original Research Article


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