LMS Adaptive Control Research Articles

Adaptive LMS MPPT Controller and Adaptive Inverter Control Law to Control the Solar Photovoltaic System

Adaptive LMS MPPT Controller and Adaptive Inverter Control Law to Control the Solar Photovoltaic System

Research on the Random Shock Vibration Test Based on the Filter-X LMS Adaptive Inverse Control Algorithm

The related theory and algorithm of adaptive inverse control were presented through the research which pointed out the adaptive inverse control strategy could effectively eliminate the noise influence on the system control. Proposed using a frequency domain filter-X LMS adaptive inverse control algorithm, and the control algorithm was applied to the two-exciter hydraulic vibration test system of random shock vibration control process and summarized the process of the adaptive inverse control strategies in the realization of the random shock vibration test. The self-closed-loop and field test show that using the frequency-domain filter-X LMS adaptive inverse control algorithm can realize high precision control of random shock vibration test.

位相補償付LMS適応制御の新しい判断法の提案

位相補償付LMS適応制御の新しい判断法の提案

位相補償付LMS適応制御に関する研究

These years, as we require the comfort at the time of boarding, it is proposed the active control engine mount (ACM), which is the equipment for automobile vibration suppression. For one of the ACM control methods, we use the Filtered-x least-mean-square (Filtered-x LMS) adaptive control system because of the simple structure. Before we use this control method, we need the transfer model that changes controller's output voltage into ACM's thrust. But because of time-related deterioration, the model has errors, which cause system's instability. So, in this paper, we will propose the LMS adaptive control algorithm which does not have to get the transfer model in advance.

An adaptive anechoic termination for active vibration control

The active broadband control of the flexural vibration of a slender structure, in particular a beam, is obtained by the use of an adaptive anechoic termination. The anechoic termination, which absorbs any energy incident upon it, is implemented by applying a force close to one end of the structure. The force is determined by a feed-forward adaptive control that uses estimates of the incident and reflected waves as reference and error signals. Digital filters are implemented to estimate, in real-time, the amplitudes of these waves by filtering the outputs of an array of sensors. The reflected wave is used as the cost function in a filtered-X LMS adaptive control. The use of the propagating waves as reference and error signals also allows the method to be effective for resonant structures, a situation in which conventional approaches fail to be reliable. In order to compare the method with a conventional approach an anechoic termination that uses the primary excitation as reference is also considered. Numerical and experimental results demonstrate the method applied to semi-infinite and finite resonant structures. A broadband reduction of up to 20 dB in the ratio of the reflected and incident powers is demonstrated both numerically and experimentally. The use of the adaptive anechoic termination to reduce the vibration levels in structures is shown to be more effective than other typical feed-forward active control systems. Furthermore, it can be applied to cases where no reference signal, such as the primary excitation, is directly available.

Sinusoidal interference rejection analysis of an LMS adaptive feedforward controller with a noisy periodic reference

This paper applies a new vector subspace model to determine the non-Wiener solutions of the LMS algorithm when the reference input is an arbitrary noisy periodic signal. The LMS weights are modeled as a deterministic time-varying mean plus a zero-mean fluctuating part. For the mean weight, each harmonic component of the periodic reference is shown to excite only a two-dimensional (2-D) subspace of the N-dimensional tap weight space. The fluctuating part of the weight is due to the reference noise that excites the full N-dimensional space. The power spectrum of the error is computed using the correlation function of the weight fluctuations. The error is shown to be primarily the sum of a white noise and the canceled periodic residual for an independent noise vector model. When the effects of the tapped delay line are incorporated in the model, the noise becomes colored with a spectrum centered about the canceled sinusoidal frequency. This weight model significantly simplifies the understanding of the non-Wiener behavior and can be applied to active noise cancellation problems when filters appear in the cancellation loop.

Active control of sound transmission through an industrial sound encapsulation

In this paper, an active control system is developed to enhance the sound transmission loss of a sound encapsulation at low frequencies. The sound encapsulation is used to shield a noise source, such as an air compressor. The control systems comprise two control loudspeakers and two error microphones. The Filtered-X LMS adaptive feedforward control algorithm is used to drive the signals at the error microphones to a minimum. The reference signal for the control algorithm is taken from the noise source, i.e., the tacho signal of the compressor. This study deals with the optimization of the location of control sources and error sensors in view of the achieved control performance. From this perspective it is important to note that minimizing the sound-pressure level at the error microphones, which are constrained to be located inside the sound encapsulation, does not necessarily reduce the acoustic intensity measured in the far field of the encapsulation (or at least, not to the same degree). Relevant issues which are considered are: the coupling of control sources with the acoustic modes of the enclosure, changes to the interior sound field due to active control, etc.

Active Noise Control in a Y-Shaped Duct: Simulation and Experimental Results

There are different approaches to active noise control (ANC). The time domain Filtered-X LMS adaptive control scheme is currently used in most applications. The purpose of this paper is to describe an experiment consisting of a Y-shaped duct with two loudspeakers attached to the two branches of the Y duct. One of the loudspeakers acts as the perturbation source and the other acts as the control source. Tonal noise control is investigated, and control implementation issues such as number of filter weights, value of step-size parameter, and sampling frequency are discussed. The reference signal is taken from the signal sent to the perturbation loudspeaker and the error signal is taken from a microphone that can be placed anywhere along the stem of the Y-shaped duct. Simulations and experimental results are presented. The setup is simple and may be easily implemented for leaching purposes.

On-line measurement of error-path impulse response for an adaptive ANR headset

A digital, adaptive ANR headset system has been developed and tested in the laboratory, using a filtered-X LMS adaptive control algorithm and a floating-point digital signal processor (DSP). The implementation of the filtered-X LMS adaptation algorithm requires an impulse response (IR) model of the so-called ‘‘error-path,’’ which consists of the serial connection of an earphone, earcup acoustics, microphone, and electronic amplifiers and filters. Though the IR model can be measured off-line for laboratory studies using standard measurement procedure, on-line measurement or identification, using the DSP engine and digital signal processing techniques, is considered necessary and advantageous for practical applications. This paper discusses a DSP-based identification technique for the error-path IR model, which employs the well-known pseudorandom binary signal (PRBS), also called the maximum length sequence (MLS) signal, as the input to the error path. In this paper, the measurement method and system will be discussed. As an example, the error-path impulse response and the corresponding ANR results obtained in a laboratory setup will be presented. [Work supported by DCIEM, Toronto, Canada.]

Broad bandwidth underwater transducer

A new underwater transducer design technique is described that provides for ultrabroad-bandwidth directive arrays that are lightweight and thin (for easy towing). An example of this new technique is a planar array that is 1 m high, 0.75 m wide, and 0.15 m thick. This array has greater than 60% radiation efficiency throughout the frequency band extending from 400 Hz to 4 kHz, and a nominal power output within this band of 10 kW. The array is neutrally buoyant, and uses Navy type-III PZT actuators. The broadband goal is met by designing the transducers in such a way that their own stiffness reactances are mostly canceled by their masslike radiation reactances over the entire operating band. This feat is accomplished both by properly adjusting the ratio of actuator cross-sectional area to radiation area, and by using low dynamic transducer mass. Since the principle of operation requires for each transducer that its motion be influenced by its own radiation load, it is necessary to control each transducer’s motion so that the desired radiation pattern is achieved. This is done by a filtered-X feedforward LMS adaptive controller.

Active control of interior noise in a business aircraft using piezoceramic control actuators

This paper describes results of experiments in which active control of interior noise in a business aircraft is achieved using piezoceramic actuators bonded to the fuselage structure. The experiments were performed in a real aircraft fuselage (Cessna Citation 3) with engine noise simulated by a point force shaker attached to the engine pylon, and multiple arrays of piezoelectric control actuators in conjunction with an LMS adaptive controller. The cost function used was the summation of the pressure squared at four error microphones located at head height in proximity of the two rear-mounted passenger seats. Results are given for on-resonance and off-resonance cases and sound level reductions from 3 to 15 dB were demonstrated. The global nature of the control and influence of the actuator/sensor positioning is discussed.