High-Order Fully Actuated Approach for Output Tracking Control of Flexible Servo Systems Subject to Uncertainties and Disturbances

In this article, a high-order fully actuated (HOFA) approach is proposed for the output tracking control of flexible servo (FS) systems with uncertainties and disturbances. The dynamics of FS systems is first converted into an HOFA model, based on which the position tracking controller can be synthesized in a straightforward way, and a linear extended state observer (LESO) is constructed to handle the “differential explosion” problem. The controller and observer gains are explicitly solved via the bandwidth parameterization method, which gains a huge benefit for practical use. Furthermore, an LESO-based disturbance observer (DO) is designed to suppress the state estimation errors, which can further improve the control accuracy. The theoretical results of control system stability are provided in an analytical way. Comparative experimental results show that the maximum control errors of the proposed approach are, respectively, reduced by 45.8% and 55.0% relative to some existing methods under uncertainties and disturbances, which demonstrates the superiority of the proposed approach.