Feedback-Linearization-Assisted Observer-Based Interconnection and Damping Assignment Passivity Control for Electromechanical Actuators

Electromechanical actuators (EMAs) are increasingly used in aerospace servo actuation because of their compact structure, high power density, and convenient integration with electric flight-control systems. However, load-side aerodynamic torque, friction, parameter perturbations, and unmodeled transmission effects enter the EMA dynamics through a channel different from the motor-current input, which leads to a mismatched disturbance rejection problem. This paper develops a feedback-linearization-assisted observer-based interconnection and damping assignment passivity-based control (IDA-PBC) method for EMA trajectory tracking. A fourth-order input–output feedback-linearized normal-coordinate model is first derived, through which the original load-side mismatched disturbance is transformed into a matched term acting on the highest-order channel. An extended state observer is then constructed to estimate the transformed disturbance. Based on the observer output, a desired Hamiltonian function is generated from a Lyapunov equation, and the interconnection and damping matrices are explicitly assigned so that the closed-loop tracking-error dynamics admit a dissipative port-Hamiltonian representation. A composite Lyapunov analysis proves closed-loop exponential stability under the assumption of slowly varying disturbance. The resulting framework combines the disturbance-channel-reshaping capability of feedback linearization with the energy-shaping interpretation of IDA-PBC, providing a systematic controller design for high-precision EMA servo systems subject to load-side disturbances.