| Title |
A Robust Control for Robot Manipulators using Output Feedback Disturbance Observer |
| DOI |
https://doi.org/10.5573/ieie.2026.63.10.65 |
| Keywords |
Output Feedback; Disturbance observer; Robust control; Robot manipulator; Nonlinear system |
| Abstract |
Robot manipulators are representative multi-input multi-output(MIMO) nonlinear systems, and they are characterized by significant system uncertainties due to the difficulty of accurately identifying their parameters. Furthermore, while joint angles are measured through sensors when controlling a robot manipulator, joint velocities are often obtained by numerically differentiating the measured joint angles. However, using joint velocities obtained via numerical differentiation may cause issues such as high-frequency noise amplification and errors stemming from sensor resolution limits. To address these problems, this paper proposes a robust output feedback controller for robot manipulators in the presence of external disturbances and system uncertainties. Due to the inherent dynamics of robot manipulators, the input gain matrix of a robot manipulator system is a nonlinear function of the joint angles. This paper extends the assumptions made in previous studies by allowing the nominal system to include a nonlinear state-dependent input gain matrix. It also presents a disturbance-observer-based output-feedback framework that guarantees the practical stability of the nominal closed-loop system. The proposed controller employs a high-gain observer and a filtering scheme to estimate and compensate for the lumped disturbance, which represents the combined effects of unmeasured states, external disturbances, and system uncertainties. Finally, simulation results are provided to demonstrate the effectiveness of the proposed method. Simulation results verified that the proposed method achieved approximately a 55.6% reduction in estimation error compared with the previous method. |