Charles E. Kinney

AN ADAPTIVE INTERNAL MODEL-BASED CONTROLLER FOR PERIODIC DISTURBANCE REJECTION

Abstract This paper details the design of an adaptive internal model-based controller to attenuate periodic disturbances in the presence of random noise. The internal model-based controller is designed in two steps, making use of the separation principle to design a controller with the desired properties that stabilizes the closed-loop system. Periodic disturbances appear as harmonics of a fundamental frequency. The fundamental frequency of the disturbance is estimated with a magnitude/phase-locked loop and is used to adjust the parameters of the controller, specifically the natural frequency of the internal model and the feedback gain. An active noise control study shows the ability of the proposed method to cancel time varying disturbances in an acoustic system.

A comparison of fixed point designs and time-varying observers for scheduling repetitive controllers

This paper presents two distinct methods of designing scheduled repetitive controllers for the case where the frequency of the disturbance is slowly varying and when it is rapidly varying. In both cases the plant is subjected to random and periodic disturbances. The first method uses set points to design a family of controllers and then interpolates between them online. The conditions for designing sub-optimal gains are given. The second method utilizes results from time-varying Riccati equations to design a time-varying observer. It is shown via simulation that the time-varying Riccati method is superior but at a greater computational cost.

Robust Estimation and Automatic Controller Tuning in Vibration Control of Time Varying Harmonic Disturbances

Abstract This paper presents theoretical and experimental results of a newly developed automatic controller tuning algorithm called Robust Estimation for Automatic Controller Tuning (REACT) to tune a linear feedback controller to the unknown spectrum of disturbances present in a feedback loop. With model uncertainty and controller perturbations described in (dual) Youla parametrizations, the REACT algorithm allows recursive least squares based tuning of a feedback controller in the presence of model uncertainty to minimize the variance of control performance related signal. It is shown how stability of the feedback can be maintained during adaptive regulation, while simulation and experimental results on a mechanical test bed of an active suspension system illustrate the effectiveness of the algorithm for vibration isolation of periodic disturbances with unknown and varying frequencies.

ACTIVE NOISE CONTROL OF A COOLING FAN IN A SHORT DUCT

In this paper we develop a data based model, design a high performance robust controller, and apply the controller in real-time to reduce narrowband acoustic noise from a cooling fan. A custom, portable enclosure houses the cooling fan. One end of the enclosure is fitted with four speakers and four microphones, inside of a short duct, connected to a data acquisition system and a personal computer. Passive materials mounted at the other end of the enclosure reduce backside noise. The frequency of the narrrowband noise is assumed unknown and therefore a control design that can be updated in realtime is needed. The control design that is presented uses a nominal model and a nominal controller. The nominal controller is enhanced by using closed loop signals and taking into account the modeling error. The end result is a data-based method for updating a nominal controller to improve performance.© 2008 ASME

Robust Estimation for Automatic Controller Tuning with Application to Active Noise Control

In this work, we show how the double-Youla parameterization can be used to recast the robust tuning of a feedback controller as a robust estimation problem. The formulation as an estimation problem allows tuning of the controller in realtime on the basis of closed loop data. Furthermore, robust estimation is obtained by constraining the parameter estimates so that feedback stability will be maintained during controller tuning in the presence of plant uncertainty. The combination of real-time tuning and guaranteed stability robustness opens the possibility to perform Robust Estimation for Automatic Controller Tuning (REACT) to slowly varying disturbance spectra. The procedure is illustrated via the application of narrow-band disturbance rejection in the active noise control of cooling fans.

PERIODIC DISTURBANCE REJECTION WITH AN INTERNAL MODEL-BASED H2 OPTIMAL CONTROLLER

In this paper a method is proposed to design an optimal controller that uses an internal model and an additive noise model to reject periodic disturbances. The proposed design method allows for the design of a feedback controller that rejects periodic disturbances in the presence of random noise. An active noise cancellation application for an HP DL380 G3 rack server cooling fan is presented to demonstrate the efiectiveness of the proposed design method. System identiflcation techniques are used to flnd a model of the non-periodic disturbances. The feedback controller was implemented in real-time to show the efiectiveness of periodic blade pass frequency sound reduction. Copyright c ∞ 2005 IFAC.

Adaptive Periodic Noise Cancellation for Cooling Fans With Varying Rotational Speed

This paper presents a novel method of simultaneously tracking and rejecting time-varying sinusoids in the presence of random noise by using feedback control. The technique extends the internal model-principle by using an extended Kalman filter to create time-varying gains and a time-varying internal model. The state feedback gain, however, is not time-varying and is designed using standard time-invariant LQR methods. This control algorithm is applied to active noise cancelation and in simulations is shown to converge quickly in the presence of noise. Methods of improving convergence of this algorithm are discussed.

Optimal microphone placement for active noise control in a forced‐air cooling system.

In active noise cancellation systems with relatively small acoustic coupling, feedforward compensation is an effective methodology to create a controlled emission for sound attenuation. Especially for small electronic systems where forced air‐cooling is required to control the temperature of large power sensitive components in the system, an active noise cancellation (ANC) system is a viable solution to reduce acoustic emissions. In this paper we discuss the placement of the noise source microphone for feedforward based active noise control in a forced‐air cooling system. Noise source microphone placement is directed by the ANC performance of an on‐line output‐error based affine optimization of a linearly parametrized generalized finite impulse response filter for sound compensation. For the computation of the optimal filter, generalized or orthogonal FIR models are used as they exhibit the same linear parametrization as a standard FIR filter. The procedure is demonstrated on a small portable NEC LT170 da...

Mutual Problems of the Physicist, the Physiologist, and the Audiologist

This paper will point out some of the physical and physiological stumbling blocks that are confronting the practicing audiologist. One or two examples of how these problems are being attacked in teaching centers where there is planned cooperation between these departments.