The adaptive regulation is an important issue with a lot of potential for applications in active suspension, active vibration control, disc drives control and active noise control. One of the basic problems from the "control system" point of view is the rejection of multiple unknown and time varying narrow band disturbances without using an additional transducer for getting information upon the disturbances. An adaptive feedback approach has to be considered for this problem. Industry needs a state of the art in the field based on a solid experimental verification. The paper presents a benchmark problem for suppression of multiple unknown and/or timevarying vibrations and an associated active vibration control system using an inertial actuator on which the experimental verifications have been done. The benchmark has three levels of difficulty and the associated control performance specifications are presented 1. An extensive comparison of the results obtained by various approaches will be presented 2. * Control system department of GIPSA-LAB, St. Martin d'héres, 38402 FRANCE (e-mail: [ioan-dore.landau, tudor-bogdan.airimitoaie, abraham.castellanos-silva, Gabriel.Buche]@gipsa-lab.grenoble-inp.fr). † Paulstra S.A.; Vibrachoc Division 1 The GIPSA-LAB team has done the experiments for all the contributors. 2 Results for some of the approaches are included in the proceedings of ECC 13[3], [8], [9], [7], [1], [18].

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International audienceThe paper presents an indirect adaptive regulation algorithm for the attenuation of unknown narrow-band disturbances. The main features of this new scheme are: (i) the use of adaptive Band-stop Filters (BSFs) tuned at the frequencies of the disturbance and (ii) a procedure for direct identification of frequencies contained in the disturbance. The use of adaptive BSFs allows one introduce the desired attenuation of the disturbance (instead of total rejection) and simplifies the shaping of the output sensitivity function (to meet the specification for the tolerated amplification outside the frequencies of the disturbance). The proposed approach is evaluated on the benchmark simulator and on the benchmark active vibration control system

International audienceIn many classes of applications like active vibration control and active noise control, the disturbances can be characterized by their frequency content and their location in a specific region in the frequency domain. The disturbances can be of narrow band type (simple or multiple) or of broad band type. A model can be associated to these disturbances. The knowledge of this model allows to design an appropriate control system in order to attenuate (or to reject) their effect upon the system to be controlled. The attenuation of disturbances by feedback is limited by the Bode Integral and the ‘water bed’ effect upon the output sensitivity function. In such situations, the feedback approach has to be complemented by a ‘feedforward disturbance compensation’ requiring an additional transducer for obtaining information upon the disturbance. Unfortunately, in most of the situations, the disturbances are unknown and time-varying and therefore an adaptive approach should be considered. The generic term for adaptive attenuation of unknown and time-varying disturbances is ‘adaptive regulation’ (known plant model, unknown, and time-varying disturbance model).The paper will review a number of recent developments for adaptive feedback compensation of multiple unknown and time-varying narrow band disturbances and for adaptive feedforward compensation of broad band disturbances in the presence of the inherent internal positive feedback caused by the coupling between the compensator system and the measurement of the image of the disturbance. Some experimental results obtained on a relevant active vibration control system will illustrate the performance of the various algorithms presented. Some open research problems will be mentioned in the conclusion

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Adaptive feedback control approaches have been widely used to address the issue of rejecting multiple narrow band disturbances with unknown and time varying characteristics (frequency, phase and amplitude), in Active Vibration Control (AVC) and Active Noise Control (ANC). These approaches are based directly or indirectly on the use of the Internal Model Principle and the Youla-Kučera parametrization combined with an adaptive law. All the algorithms associated with these approaches make the assumption that the plant zeros are different from the poles of the disturbance model in order to achieve disturbance compensation. However in practice the problem is more intricate since it is not clear what happens if the plant has very low damped complex zeros (often encountered in mechanical structures) and the frequency of the disturbance is close to the anti-resonance frequency (the resonance frequency of the plant zeros). In this paper we evaluate comparatively in simulation and in real time on a benchmark test bed, two different approaches to deal with the low damped complex zeros of the plant. An evaluation of the combination of the two approaches is also presented.

International audienceThe paper presents a direct adaptive algorithm for the rejection of unknown time-varying narrow band disturbances, applied to an adaptive regulation benchmark. The objective is to minimize the residual force by applying an appropriate control signal on the inertial actuator in the presence of multiple and/or unknown time-varying disturbances. The direct adaptive control algorithm is based on the internal model principle (IMP) and uses the Youla-Ku\v cera (YK) parametrization. A direct feedback adaptive regulation is proposed and evaluated both in simulation and real-time. The robustness is improved by shaping the sensitivity functions of the system through band stop filters (BSF)

A direct adaptive regulation scheme using a FIR Youla-Kučera Filter has been proposed for solving the EJC Benchmark [4] for rejection of multiple unknown and timevarying narrow-band disturbances. Despite the excellent results this approach requires a careful design of the central controller in terms of selection of some of the assigned closed-loop poles. A modified scheme is proposed in this paper which will incorporate a particular adaptive IIR Youla-Kučera Filter. Called ρ-notch structure (the denominator is a projection inside the unit circle) of the model of the disturbance which has roots on the unit circle. The adaptive scheme estimates separately the numerator and denominator parameters of the IIR Youla-Kučera Filter. Stability and convergence proofs are given along with simulation and real-time results. Comparison with results already obtained for the EJC Benchmark are provided. The use of this approach drastically simplify the design of the central controller and provide even better results than [4] with the advantage to use a single central controller independently of the number of narrow band disturbances.