Multiple Narrow Band Disturbances Research Articles

Systematic Control Design for Adaptive Rejection of Narrow-Band Disturbances Based on a Novel Resonant Generalized Extended State Observer

In this paper, the adaptive rejection of multiple narrow-band disturbances with time-varying frequencies is investigated. A systematic control approach based on a resonant generalized extended state observer (RGESO) is proposed. The frequency response of the RGESO is shaped into a desired form to reject the total disturbance, including the wide-band uncertainties and the narrow-band disturbances. The state-space realization of the RGESO is also provided to estimate both the states and the total disturbance. To handle the time-varying frequencies of the narrow-band disturbances, a direct frequency estimation approach based on the Levenberg–Marquardt method and an online supervision strategy is presented to improve convergence and reliability, and the estimations are then used to adapt the RGESO parameters. Parameter tuning and stability robustness analysis methods are also developed for the proposed scheme to facilitate its application. Finally, extensive simulations are conducted to demonstrate the effectiveness of our method.

Parallel-filter-based observer control for unknown multiple narrow-band disturbance rejection

An observer-based control method with parallel Q-filter is proposed to reject unknown multiple narrow-band disturbances for line of sight stabilization in telescope systems. In general, wide-band or multiple narrow-band disturbances rejection of observer-based control can be transformed into designing Q-filter, which could be too high-order to achieve fully-accuracy digital implementation, resulting in degrading the closed-loop performance or even causing instability. Therefore, a new parallel type of Q-filters is proposed to flexibly adjust the number of Q-filter in the sensitivity function and effectively reduce the computational complexity. A sufficient condition of the effectiveness for the parallel Q-filter and the closed-loop stability is derived and verified through simulations. Furthermore, disturbance frequencies can be on-line identified to adaptively optimize the Q-filter parameters. The effectiveness of the proposed method is validated on the image-based stabilization subsystem of a segmented lightweight large-scaled diffractive telescope.

Handling large model uncertainty in adaptive feedback noise attenuation by overparametrization

Adaptive feedback noise attenuation is a very efficient way of strongly attenuating multiple tonal and narrow band disturbances with unknown and time varying characteristics. These adaptive schemes implement the internal model principle (IMP) for canceling disturbances combined with the Youla Kucera (YK) parametrization which allows to directly tune the disturbance compensation filter without explicit identification of the disturbance model. Efficient use of these schemes requires a good knowledge of the compensatory path model, which can be obtained by experimental system identification. However, there are potential applications where the characteristics of the compensatory path may change significantly during operation and this may lead to the instability of the system. The paper addresses the problem of handling large plant model uncertainties by overparametrization of the adaptive disturbance compensation filter. A methodology for designing adaptive feedback noise cancelers in the presence of large model uncertainties is proposed. In addition to the overparametrization, a specific design of the linear feedback controller has to be done in order to satisfy a frequency condition in the range of variations of the frequencies characteristics of the compensatory path model. Experimental validation of the design is done on a relevant active noise control bench test.

Youla parameterized adaptive vibration suppression with adaptive notch filter for unknown multiple narrow band disturbances

The vibration caused by the multiple narrow band disturbances exists widely in the mechanical systems. In this paper, a Youla parameterized adaptive control approach is introduced for the rejection of unknown multiple narrow band disturbances. The adaptive notch filter weighted Q (Youla) parameter is adopted to the online internal model principle-based regulator, so that the disturbances can be fully attenuated and the robustness of the closed-loop system is improved. A central controller is first designed to obtain the desired baseline loop shape. Then, the controller is augmented by a notch filter weighted Q parameter to construct a series of stable controllers and the Q parameter in the stable controllers is tuned online to obtain the desired controller. The adaptive control method is applied in a data storage system to attenuate the flying height vibration and the experimental results illustrate the effectiveness of the proposed approach in rejecting unknown multiple narrow band disturbances.

Robust and Adaptive Feedback Noise Attenuation in Ducts

In this brief, the attenuation of sound propagation in an air-handling duct using robust and adaptive feedback active noise control (ANC) strategies is investigated. The case of multiple narrow-band disturbances located in distinct frequency regions and the interference occurring in the presence of disturbances with very close frequencies are considered. The active control uses a loudspeaker as a compensatory system. The objective is to minimize the residual noise at the end of the duct segment considered. The system does not use any additional sensors for receiving real-time information upon the disturbances. This brief illustrates the application of the techniques for active vibration control presented by Landau et al. to this problem. A hierarchical feedback control approach will be used. At the first level, a robust linear controller will be designed taking advantage of the knowledge of the domains of variation of the frequencies of the noise disturbances. To further improve the performance, a direct adaptive control algorithm will be added. Its design is based on the use of the internal model principle combined with the Youla–Kucera parameterization of the controller. Guidelines for the design of the baseline (central) controller are provided. Both robust and adaptive controls require the knowledge of the discrete-time model of the compensation path, which is obtained by identification from experimental data. Experimental results on a relevant duct ANC test bench will illustrate the performance of the proposed methodology.

Modified direct adaptive regulation scheme applied to a benchmark problem

A direct adaptive regulation scheme using an adaptive FIR Youla–Kučera Filter has been proposed for solving the EJC Benchmark on rejection of multiple unknown and time-varying narrow-band disturbances (Castellanos Silva et al., 2013 [4]). Despite 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 poles 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 is provided. The use of this approach drastically simplifies the design of the central controller and provides even better results than (Castellanos Silva et al., 2013 [4]) with the advantage to use a single central controller independent of the number of narrow band disturbances.

Robust Direct Adaptive Regulation of Unknown Disturbances in the Vicinity of Low-Damped Complex Zeros--Application to AVC

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 and active noise control. These approaches are directly or indirectly based on the use of the internal model principle and the Youla–Kucera 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 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 antiresonance frequency (the resonance frequency of the plant zeros). In this brief, we comparatively evaluate 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.

Indirect Adaptive Attenuation of Multiple Narrow-Band Disturbances Applied to Active Vibration Control

In this brief, an indirect adaptive control methodology for attenuation of multiple unknown time varying narrow-band disturbances is proposed. This method is based on the real time estimation of the frequency of narrow-band disturbances using adaptive notch filters followed by the design of a controller using adjustable band-stop filters for the appropriate shaping of the output sensitivity function. A Youla-Kučera parametrization of the controller is used for reducing the computation load. This approach is compared on an active vibration control system with the direct adaptive control scheme based on the internal model principle proposed. Real time experimental results are provided.

Corrections to "A minimum parameter adaptive approach for rejecting multiple narrow-band disturbances with application to hard disk drives" [Mar 12 408-415

In the above-named article [ibid., vol. 20, no. 2, pp. 408-415, Mar. 2012], the numerator of (29) contained errors. The corrected equation is provided.

Youla parameterized adaptive regulation against unknown multiple narrow-band disturbances

An adaptive regulation approach in linear systems against exogenous inputs consisting of a linear combination of sinusoids with unknown amplitudes, frequencies and phases is proposed within the framework of Youla parameterized stabilizing controllers. The goal of the developed adaptation algorithm is to search, within the set of weighted Ritz-type Youla parameters, for a controller that yields regulation in the closed-loop system. The proposed approach is applied to an active vibration control problem, and the performance of the developed regulator is illustrated by considering the vibration cancellation against exogenous inputs represented as a linear combination of unknown stationary as well as time-varying sinusoidal disturbances.

H∞ gain-scheduled controller design for rejection of time-varying narrow-band disturbances applied to a benchmark problem

A new method for H∞ gain-scheduled controller design by convex optimization is proposed that uses only frequency-domain data. The method is based on loop shaping in the Nyquist diagram with constraints on the weighted infinity-norm of closed-loop transfer functions. This method is applied to a benchmark for adaptive rejection of multiple narrow-band disturbances. First, it is shown that a robust controller can be designed for the rejection of a sinusoidal disturbance with known frequency. The disturbance model is fixed in the controller, based on the internal model principle, and the other controller parameters are computed by convex optimization to meet the constraints on the infinity-norm of sensitivity functions. It is shown next that a gain scheduled-controller can be computed for a finite set of disturbance frequencies by convex optimization. An adaptation algorithm is used to estimate the disturbance frequency and adjusts the parameters of the internal model in the controller. The simulation and experimental results show the good performance of the proposed control system.

Benchmark on adaptive regulation—rejection of unknown/time-varying multiple narrow band disturbances

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 to know the state of the art in the field based on a solid experimental verification on a representative system using currently available technology. The paper presents a benchmark problem for suppression of multiple unknown and/or time-varying vibrations and an associated active vibration control system using an inertial actuator with which the experimental verifications have been done. The objective is to minimize the residual force by applying an appropriate control effort through the inertial actuator. The system does not use any additional transducer for getting real-time information about the disturbances.The benchmark has three levels of difficulty and the associated control performance specifications are presented. A simulator of the system has been used by the various contributors to the benchmark to test their methodology. The procedure for real-time experiments is briefly described.11The GIPSA-LAB team has done the experiments for all the contributors. The performance measurement methods used will be presented as well as an extensive comparison of the results obtained by various approaches.22Simulation and Real-time results are presented by each contributor in their papers [3,11,17,30,10,1,7].

Adaptive Attenuation of Unknown and Time Varying Disturbances

Abstract In many classes of applications like active vibration control and active noise control the disturbances can be characterized by their frequencies 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 getting 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 narrowband 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.

An indirect adaptive scheme for attenuation of multiple narrow-band disturbances: stability analysis

In this paper, a stability proof for an indirect adaptive control method used for the attenuation of multiple unknown time varying narrow-band disturbances is presented. The method is based on the real time estimation of the frequency of the unknown narrow-band disturbances using adaptive notch filters (ANF) followed by the design of a controller using adjustable band-stop filters (BSF) for the appropriate shaping of the output sensitivity function. An Youla-Kučera parametrization of the controller is used for reducing the computation load. Sufficient conditions for stability of the full scheme are stated and a stability proof is given. Finally, an experimental comparison with a direct adaptive method based on the internal model principle (IMP) is shown.

A Minimum Parameter Adaptive Approach for Rejecting Multiple Narrow-Band Disturbances With Application to Hard Disk Drives

Many servo systems are subjected to narrow-band disturbances that generate vibrations at multiple frequencies. One example is the track-following control in a hard disk drive (HDD) system, where the airflow-excited disk and actuator vibrations introduce strong and uncertain spectral peaks to the position error signal. Such narrow-band vibrations differ in each product and can appear at frequencies above the bandwidth of the control system. We present a feedback control scheme that adaptively enhances the servo performance at multiple unknown frequencies, while maintaining the baseline servo loop shape. A minimum parameter model of the disturbance is first introduced, followed by the construction of a novel adaptive multiple narrow-band disturbance observer for selective disturbance cancellation. Evaluation of the proposed algorithm is performed on a simulated HDD benchmark problem.

Adaptive regulation—Rejection of unknown multiple narrow band disturbances (a review on algorithms and applications)

The paper addresses the problem of attenuation (rejection) of unknown and time varying multiple narrow band disturbances without measuring them. In this context the disturbance model is unknown and time varying while the model of the plant is known (obtained by system identification) and almost invariant. This requires to use an adaptive feedback approach. The term “adaptive regulation” has been coined to characterize this control paradigm. Application domains include: mechanical and mechatronics systems, active vibration and noise suppression systems, some types of bio-chemical reactors. The paper reviews the various techniques proposed for solving this problem. It will focus on the presentation of the direct and indirect adaptive regulation strategies using the internal model principle and the Youla–Kucera parametrization which have been extensively used in applications. The paper also reviews a number of applications including: active suspension systems, active vibration control systems, active noise control, bio-chemical reactors, distributed flexible mechanical structures and Blu-ray disc drives. Real time results obtained on various applications will illustrate the methodology.

An Indirect Adaptive Approach to Reject Multiple Narrow-Band Disturbances in Hard Disk Drives

This paper presents an indirect adaptive control scheme that rejects unknown multiple narrow-band disturbances in hard disk drive systems. The proposed algorithm first finds the model of the disturbance (the internal model) and then adaptively estimates its parameters. The design of a band-pass filter with multiple narrow pass-bands is then presented and used to construct a disturbance observer (DOB) for disturbance rejection. The proposed algorithm estimates the minimal amount of parameters, and is computationally simple. Evaluation of the proposed algorithm is performed on a benchmark problem for HDD track following.

Multi-frequency disturbance rejection via blending control technique for hard disk drives

This paper is concerned with the rejection of multiple narrowband disturbances in hard disk drives (HDDs). Inspired by a control blending idea, the multi-frequency disturbance rejection is formulated as a blending control problem. Each disturbance rejection is accomplished by using the H 2 optimal control method. Based on all H 2 optimal controllers, the blending technique is applied to yield a single controller which is capable of achieving rejection of all disturbances. Rejections of two and three disturbances for a 1.8-inch HDD VCM actuator are taken as application examples in the paper. Simulation and experimental results show that the ultimate controller results in a simultaneous attenuation of disturbances with frequencies higher or lower than the closed-loop system bandwidth. Moreover, the method turns out to be able to lift phase and thus prevent phase margin loss when it is used to deal with disturbances near bandwidth.