Acceleration Measurement-Free Dissipative Disturbance Observer for Robotic Manipulators

In this letter, we propose an Acceleration Measurement-Free Dissipative Disturbance Observer (AFDDO) for robotic manipulators, designed to estimate external disturbances robustly without requiring angular acceleration measurements and matrix inversion. By leveraging dissipativity theory, the AFDDO achieves enhanced robustness and stability against fast-varying disturbances. A linear matrix inequality (LMI)-based approach is employed for observer gain tuning, enabling efficient computation and control of observer bandwidth. Unlike conventional methods, the AFDDO eliminates the need for matrix inversion and utilizes generalized momentum to maintain an acceleration measurement-free condition. The proposed observer was validated through simulations and experiments using a mini-hydraulic excavator, demonstrating superior performance in disturbance estimation compared to existing nonlinear disturbance observers.