Adaptive LADRC-based Disturbance Rejection Method for Electro-Mechanical Servo System

Electromechanical actuator (EMA) exhibits advanced performance in industry, but its dynamic servo responses are constrained by parametric perturbations, load torque variations, and measurement noise. A strong disturbance rejection ability is necessary for EMAs. However, this usually makes them more sensitive to the measurement noise, reducing the steady-state precision. In this article, an adaptive linear active disturbance rejection control (LADRC) controller is proposed to achieve strong antidisturbance performance and reduce noise sensitivity for EMAs. A novel parallel structure is proposed to improve dynamic responses, which replaces the traditional cascade structure of position and speed loops. Aiming to improve the antidisturbance performance, a linear full-order-extended state observer is integrated with the parallel controller, called the LADRC controller. To reduce the difficulty of parameter tuning, the number of tuning parameters of LADRC is reduced to two by a pole placement design. And these two parameters of LADRC can be adjusted adaptively by the hyperbolic tangent function. Finally, the simulation and experimental results are provided to verify the effectiveness of the proposed strategy for EMAs.