Multiharmonic Disturbance Research Articles

Study on the Mechanism and Suppression of Harmonic Vibration of AMB-Rotor System

The AMB-rotor system is complex and has strong coupling characteristics, which allows multi-harmonic disturbances to enter the system through different ways to produce vibrations with rich spectrum components, which has a great influence on the improvement of micro-vibration accuracy of the rotor system. To further achieve active control of the micro-vibration in the AMB-rotor system, firstly, the mechanism of multi-source disturbance is analyzed according to the working principle of the AMB-rotor system, and the mathematical and physical relationship between the mechanism of disturbance generation and the inducement is deeply studied. Then, the structure of a novel adaptive notch filter, the method of adaptive frequency estimation and analysis of harmonic current suppression in the AMB system are presented. Finally, simulation and experimental research using an MSCMG system demonstrate the feasibility of the proposed method regarding the elimination of harmonic control current.

An adaptive feedforward method in active vibration control for the propulsion shafting system

This paper proposes a new adaptive feedforward control method for the rejection of multiple periodic disturbances in the propulsion shafting system. The active vibration control scheme of the propulsion shafting system is established by employing the equivalent-input-disturbance principle which reduces the complexity of the control system in applications. The adaptive control algorithm is designed by taking the scale transformation procedure and the frequency-tracking technique into consideration. The scale transformation normalizes the iso-surface of the optimization function by the frequency response characteristics of the control channel, which immensely improves the convergence rate of the control algorithm for multi-harmonic disturbance. Moreover, the adaptive controller tracks the fluctuating frequencies in a direct method, enhancing the efficiency and robustness of the algorithm for eliminating time-varying disturbances. Finally, numerical simulation and experimental validation are carried out to show that the proposed method has good performance on the application of the active vibration control of the propulsion shafting system.

Cancellation of unknown multi-harmonic disturbances in multivariable flexible mechanical structures

Active vibration control of flexible mechanical structures is a challenging field of research in control engineering due to typically high state-space dimensions of the plant models and the resulting multi-modal dynamical behavior. This work deals with the cancellation of unknown multi-harmonic disturbances in such flexible mechanical structures with multiple inputs and multiple outputs. The proposed control scheme exploits the passivity property of the closed-loop system to ensure robustness to unknown and slowly varying plant parameters. The controller design follows a decentralized control approach, which features a high flexibility in terms of the number of available actuators. However, the unknown disturbance frequency is estimated in a centralized way. Here, the frequency estimator switches between individual outputs based on the estimated amplitudes of the compensation scheme. This leads to an improved rate of convergence compared to a fixed output frequency estimator while retaining the high flexibility of the controller design regarding the number of available actuators. In this work, the local exponential stability of the respective nonlinear time-varying switched error dynamics is proven. Furthermore, measurements from an experimental test rig for electromagnetic stabilization of thin steel strips demonstrate the effectiveness and robustness of the proposed control scheme.

Dynamic positioning of a sea vessel under the influence of a multi-harmonic external disturbance

The paper considers the problem of dynamic positioning nonlinear model of a vessel under the multi-harmonic disturbances. The multipurpose control law makes it possible to tune the nonlinear observer, the feedback control, the dynamic corrector, and the estimator of external disturbances frequencies independently from each other. We achieve the economical ship control mode by tuning the dynamic filter to the primary external perturbation frequency. We apply a finite time approach to construct estimates of multi-harmonic external disturbance frequencies.

Non-Collocated Position Control of Steel Strip With Electromagnetic Rejection of Unknown Multi-Harmonic Disturbances

Many industrial processes are affected by periodic disturbances. For instance, vibration of steel strips in hot-dip galvanizing lines entail an inhomogeneous zinc coating of the final product. Excitation by periodic disturbances is also frequently encountered in other control systems. Thus, a number of customized methods for rejection control of unwanted oscillations have been developed in the literature. In this paper, a method for eliminating a multi-harmonic periodic disturbance at an arbitrary user-defined position of a steel strip is proposed. The control task is particularly complicated because the disturbance input, a (single) displacement sensor, a (single) electromagnetic actuator, and the system output to be controlled are located at different positions along the strip. In addition, the electromagnetic actuator used as control input features neither a force sensor nor a distance sensor for measuring the air gap between the strip and the magnetic core. Hence, the actuator operates in a pure feedforward mode. The developed control method is validated by means of an experimental test rig that mimics a scenario from an industrial hot-dip galvanizing line.

Output Adaptive Switching Controller Design with DREM-Based Multi-Harmonic Disturbance Cancellation

A new DREM-based (Dynamic Regressor Extension and Mixing) modification for output adaptive controller with input multi-harmonic disturbance cancellation is proposed in this paper. This approach provides monotonic convergence of the disturbance internal model parameters’ estimates to its true values. We also introduce a novel algorithm for the DREM-based estimator gains tuning in order to improve convergence under poor excitation. Parallel kinematics Ball-and-Plate robotic system is considered as a test-bed, while the non-prehensile ball stabilization in a predefined coordinates under bounded disturbances is a task to be solved.

Algorithm of multiharmonic disturbance compensation in linear systems with arbitrary delay: internal model approach

Algorithm of multiharmonic disturbance compensation in linear systems with arbitrary delay: internal model approach

Output Control Approach for Delayed Linear Systems with Adaptive Rejection of Multiharmonic Disturbance

We present a new output control approach for a linear plant with input delay and an unknown multiharmonic disturbance acting on the input and the output. To solve this problem, we combine the well-known predictor feedback approach with the state observer and adaptive scheme that identifies the frequency of the disturbance. Compared to the existing approaches, the structure of our adaptive scheme is the simplest and the results apply to plants that are unstable, non-minimum phase, and have an arbitrary relative degree.

A multi-harmonic amplitude and relative-phase controller for active sound quality control

Current active sound quality control systems aim at dealing with the amplitude level of the primary disturbance, e.g. sound pressure, forces, velocities and/or accelerations, which implicitly leads to Loudness control, regardless of the spectral structure of the disturbance. As far as multi-harmonic disturbances are concerned, auditory Roughness, arguably the most related psychoacoustic metric with rumbling perception in passenger cars, can be tackled not merely by dealing with magnitudes but also with the relative-phase of the narrowband components. This paper presents an adaptive control scheme conceived for dealing with multi-harmonic disturbances, which features the independent amplitude and/or relative-phase control of the input periodic components and an improved robustness to impulsive events. The adaptive control scheme is based on a frequency-domain delayless implementation of the complex-domain, least mean squares algorithm, whereof its convergence process is improved by using a forgetting factor. The control capabilities are evaluated numerically for single- and multiple-harmonic disturbances, including realistic internal combustion engine sound contaminated with noise and by impulsive events. By using long transfer paths obtained from a real vehicle mock-up, sound pressure level reductions of 39 dBSPL and the ability to displacing the relative-phase of a number of narrowband components between [−π,π] are accomplished by the proposed control scheme. The assessment of the results by using Zwicker-Loudness and auditory Roughness models shows that the proposed adaptive algorithm is able to accomplish and stably preserve various sound quality targets, after completion of the robust convergence procedure, regardless of impulsive events that can occur during the system operation.

Double Feedforward Control System Based on Precise Disturbance Modeling for Optical Disk

Optical disk drive systems must realize high-precision tracking control for their proper operation. For this purpose, we previously proposed a tracking control system that is composed of a high-gain servo controller (HGSC) and a feedforward controller with an equivalent-perfect tracking control (E-PTC) system. However, it is difficult to design the control parameter for actual multi-harmonic disturbances. In this paper, we propose a precise disturbance model of an actual optical disk using the experimental spectrum data of a feedback controller and describe the design of a fine tracking control system. In addition, we propose a double feedforward control (DFFC) system for further high-precision control. The proposed DFFC system is constructed using two zero phase error tracking (ZPET) control systems based on error prediction and trajectory command prediction. Our experimental results confirm that the proposed system effectively suppresses the tracking error at 6000 rpm, which is the disk rotation speed of Digital Versatile Disk Recordable (DVD+R).

Fast Compensation of Unknown Multiharmonic Disturbance for Nonlinear Plant with Input Delay

In this paper a new approach for fast rejection of unknown multiharmonic disturbance is proposed. To design this algorithm the method of cascade reduction is used that allows to accelerate the process of convergence of unknown frequencies estimates. Additionally, the proposed approach differs from the known results. In this article we consider the case of disturbance rejection, when a relative degree of the plant can be arbitrary and only an output is variable, the control signal is measured and the control channel is characterized by delay.

Rejection of Multiharmonic Disturbance Approach Based on Simple Adaptive Control Principle

This paper deals with control algorithms development for output stabilization of the parametrically uncertain linear plant of unknown relative degree. Simple adaptive control paradigm lies in the basis of proposed approach. Controller was supplemented with the switching-based scheme of substitution of multiharmonic external disturbance frequencies' estimations that improves controller performance without its significant complication. Stability analysis of the closed-loop hybrid system was conducted and corresponding conditions on switching parameters were stated.

高速光ディスク装置のトラッキング誤差オフセットと高次高調波外乱の抑圧制御系

This paper proposes a control system for suppressing tracking error offset and multiharmonic disturbance in high speed optical disk systems. Residual tracking error consists of primary harmonics, high-order harmonics, and offset. Therefore, this paper proposes a tracking control system for suppressing residual tracking error, including primary harmonics, high order harmonics disturbance, and offset. The cause of the offset included in the residual tracking error is discussed. The cause is found to be the operation error in the fixed-point DSP (digital signal processor) and the phase lag of the LPF (low pass filter). Moreover, the proposed control system is designed for two types of high-speed optical disk system. The experimental results show that the proposed system enables an optical disk system to achieve a fine tracking performance.

Cancelation of unknown multiharmonic disturbance for nonlinear plant with input delay

SUMMARYIn this paper, a new approach for cancelation of a multiharmonic disturbance is proposed. Compared with a number of known results in this paper, the disturbance cancelation problem is solved when the output variable is measured only, a relative degree of the plant is arbitrary and the control channel has delay. The numerical example is presented to illustrate the theoretical result. The reaction wheel pendulum on a movable platform is considered as the plant to demonstrate that the proposed approach is realizable and can be plugged in practice. The second goal is the development of mechatronic applications for use in education. Copyright © 2011 John Wiley & Sons, Ltd.

Compensation of unknown multi-harmonic disturbances in nonlinear plants with delayed control

A new algorithm is developed for compensation of parametrically uncertain multi-harmonic disturbances affecting a control plant. In contrast to the known results, this paper deals with the situation where the relative degree of the plant is arbitrary, the only measured signals are output and control, and there exist delays in the control channel.

Compensation of Unknown Multiharmonic Disturbance for Nonlinear Plant with Delay in Control

In this paper a new approach for cancellation of a multiharmonic disturbance is proposed. Compared with a number of known results in this paper the disturbance compensation problem is solved when the output variable is measured only, a relative degree of the plant is arbitrary and the control channel has delay. The numerical example is presented to illustrate theoretical result and the reaction wheel pendulum on a movable platform is considered as the plant to demonstrate that proposed approach is realizable and can be plugged in practice. Created by hand disturbance moves the platform in horizontal surface and the pendulum is oscillating. The second goal of this work is the development of mechatronic applications using in education.

Experimental Vibration Control of a Single-Degree of Freedom System Using a State-Switched Absorber

A state-switched absorber (SSA) is a device capable of instantaneously switching between resonance frequencies, increasing its effective bandwidth as compared to classical tuned vibration absorbers (TVAs) for vibration control. Previous simulations show that for a system subjected to a multi-harmonic disturbance, the SSA reduces vibration more effectively than classical TVAs. This study considers the experimental performance of the SSA for vibration suppression of an elastically mounted lumped mass base. State switching is achieved using a clutch to connect or disconnect a coil spring in parallel with other coil springs. An SSA system outperforms a classical TVA system for several combinations of forcing frequencies.

AN ALTERNATIVE FEEDBACK STRUCTURE FOR THE ADAPTIVE ACTIVE CONTROL OF PERIODIC AND TIME-VARYING PERIODIC DISTURBANCES

An alternative feedback structure, inspired from a speech coding structure, is introduced for the adaptive active control of periodic and time-varying periodic disturbances. The new structure is an Internal Model Control (IMC) structure. It separates the information and the processing pertaining to the plant from the information and the processing pertaining to the disturbance signal. A non-causal filter modelling the inverse of the secondary path is used, and the future samples of the disturbance signal are estimated by linear prediction (using an LMS algorithm). No filtering of a reference signal with the model of the secondary path is required to compute a filtered reference signal. In consequence, for the cases presented in the paper, the new feedback structure has a much faster convergence behavior and a better transient response than the classical FX-LMS algorithm with a feedback IMC structure, or the more recent and usually faster ANC-LMS algorithm with the same IMC structure. Simulation results with experimentally measured primary and secondary paths of a beam are presented, showing that either for multi-harmonic disturbances signals or sweeping sine wave disturbances, the structure presented in this paper greatly improves the convergence behavior of an adaptive feedback controller.

An alternative feedback structure for the adaptive active control of time-varying periodic or time-varying narrow-band disturbance

For the feedback active control of noise and vibrations, there are still a few situations where today’s adaptive control algorithms do not perform well (slow convergence and/or bad transient response). In this paper, a feedback structure suited for the control of time-varying periodic or time-varying narrow-band disturbances is inspired from a technique used in today’s low bit-rate speech coders. The main concept is to separate the information and the processing pertaining to the plant from the information and the processing pertaining to the excitation signal (disturbance). Since the time constants of the variations of the plant are usually much longer than the time constants of the disturbance fluctuations, the adaptation effort can then be put on the prediction of the disturbance. Simulations will be presented, showing that either for low damping systems or multiharmonic disturbance signals, the algorithm presented in this paper can be compared favorably to a popular internal model control (IMC) structure that uses a stochastic gradient algorithm. [Work supported by I.R.S.S.T.]