DESIGN OF DELAYED REFERENCE CONTROLLERS FOR SIMULTANEOUS PATH TRACKING AND ACTIVE VIBRATION DAMPING OF MULTI-DEGREE-OF-FREEDOM LINEAR SYSTEMS

This paper presents an innovative non-time-based control strategy for the simultaneous path tracking and active vibration damping of multi-degree-of-freedom linear systems. The fundamental difference between the proposed scheme, and those that have already appeared in literature, is that it allows keeping the coordinated motion of different actuators. In other words, the use of such a scheme guarantees that a desired path in space is accurately followed while suppressing the undesired vibrational effects. The control strategy consists in actively suppressing the undesired vibrations by suitably changing the path reference for the system. Such a result can be achieved by making the path reference for the system be a function of an action reference parameter rather than just the time. The reference parameter depends on time and on a variable which plays the role of a time delay. The latter is computed on the fly, on the basis of the measured vibration. A cascade control structure is obtained, where no specific position controllers or actuators are to be employed in the inner loop. The theory developed is demonstrated through numerical simulations by applying it to the vibration and path tracking control of a four-degrees-of-freedom two-mass system.