Position and Velocity Estimation for Two-Inertia System with Nonlinear Stiffness Based on Acceleration Sensor.

Area of Science:

• Robotics
• Control Systems Engineering
• Nonlinear Dynamics

Background:

• Flexible joint manipulators exhibit complex nonlinear stiffness characteristics.
• Accurate state estimation is crucial for control and performance.
• Existing methods may struggle with unmodeled nonlinearities.

Purpose of the Study:

• To develop a robust state estimation method for flexible joint manipulators.
• To address challenges posed by nonlinear stiffness in manipulator dynamics.
• To improve the accuracy and reliability of state estimation.

Main Methods:

• Proposed a nonlinear observer utilizing accelerometer measurements.
• Modeled nonlinear stiffness as a Lipschitz function.
• Designed observer gains using algebraic Riccati equations (ARE) based on the Lipschitz constant.

Main Results:

• Estimation error dynamics are independent of manipulator link nonlinearities.
• The nonlinear observer effectively estimates states under Lipschitz stiffness conditions.
• Experimental results validate the proposed method's effectiveness.

Conclusions:

• The proposed nonlinear observer provides accurate state estimation for flexible joint manipulators.
• The approach effectively handles nonlinear stiffness using Lipschitz function properties.
• Accelerometer integration and ARE-based gain selection enhance robustness and performance.