In this paper, we propose a control design method for single-link flexible manipulators. The proposed technique is based on the integral resonant control (IRC) scheme. The controller consists of two nested feedback loops. The inner loop controls the joint angle and makes the system robust to joint friction. The outer loop, which is based on the IRC technique, damps the vibration and makes the system robust to the unmodeled dynamics (spill-over) and resonance frequency variations due to changes in the payload. The objectives of this work are: 1) to demonstrate the advantages of IRC, which is a high-performance controller design methodology for flexible structures with collocated actuator-sensor pairs and 2) to illustrate its capability of achieving precise end-point (tip) positioning with effective vibration suppression when applied to a typical flexible manipulator. The theoretical formulation of the proposed control scheme, a detailed stability analysis and experimental results obtained on a flexible manipulator are presented.

Integral resonant control (IRC) has been recently introduced as a simple, robust and high-performance technique for vibration control of smart structures instrumented with collocated piezoelectric actuator–sensor pairs. This work deals with the design and implementation of an active vibration control (AVC) system based on an IRC strategy for the mitigation of human-induced vibrations in light-weight civil engineering structures, such as floors and footbridges, via proof-mass actuators. This work presents a new AVC strategy that combines an approximate inversion of the proof-mass actuator dynamics with an IRC-based strategy. The result is a control scheme with the following desirable characteristics: (i) the closed-loop system exhibits very high stability margins, (ii) the risk of stroke saturation at low frequencies is significantly reduced so that the saturation nonlinearity, which has to be included to keep the system hardware safe, can be designed to account only for force saturation (i.e. the actuator performance is enhanced), (iii) rigorous stability analysis and systematic design can be proposed and (iv) it is not necessary to measure the actuator force. The stability analysis is carried out using the recently developed stability theorem based on the positive feedback interconnection of systems with negative imaginary frequency response. The control scheme is validated on a full-scale prestressed concrete laboratory structure. Excellent vibration reduction performance is reported for frequency-response-function-based tests and for walking excitations. Copyright © 2010 John Wiley & Sons, Ltd.