From robust control to antiwindup compensation of electrohydraulic servo actuators

Abstract

A method of designing the controller to solve the robust servomechanism problem is applied in the case of an electrohydraulic servo actuating primary flight control. This method is based on the well‐known solution consisting of two separate devices: a servocompensator, in fact an internal model of the exogenous dynamics, including the reference commands and disturbance signals; and a stabilizing compensator. The proof is made involving the servocompensator structure which is close to the one designed for step signals. The stabilizing compensator is assured by way of a linear quadratic optimal procedure. An antiwindup compensation is added to deal with the adverse effects caused by actuator saturation.

Backstepping design for controlling electrohydraulic servos

“…The alternating MM (40) of the MHS SMHR promote a somewhat ''stiffer'' object; the same is the conclusion concerning system (21) governed by the control (22). Fig.…”

“…A relatively good tracking of references r is possible with the MHS SMHR (39), but only in the absence of perturbations [22,23]. To have in this servo a concrete term of comparison for the position control technique developed in Section 2, we choose the step input r ¼ 0:17 cm=l ¼ 0:255 cm.…”

“…The transient regime is stable, irrespective of stationary regime values x 1s (admissible) and t 1r ; however, the designer must be attentive to control saturation. To counteract this effect, special antiwindup strategies can be used [3,22,23].…”

“…(39), with a simple, rigid mechanical position feedback; Eq. (2), with control law (4); (13), with control law (14); (40), with a simple, rigid mechanical position feedback; and (21), with control law (22); in the last two cases, initial conditions on the variables x 3 and x 4 were chosen 1 da N/cm 2 .…”

“…Numerical simulations have been performed to investigate the performance of the proposed nonlinear controllers, in the three cases defined by the nonlinear control laws (4), (14) and (22). Zero initial conditions-corresponding to the zero equilibrium points-were chosen for a fourth-order Runge-Kutta integration (with integration step 0.001 s) of the systems: Eq.…”