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Xiangning Fan - One of the best experts on this subject based on the ideXlab platform.

  • Spur-Free MASH DDSM with Eliminable Dither
    2017
    Co-Authors: Yilong Liao, Xiangning Fan
    Abstract:

    This paper presents a new Dither adding method for multistage-noise-shaping (MASH) digital delta-sigma modulator (DDSM), to reduce the output spurious tones. In this method, the additive Dither Signal is added to two different nodes of any preceding stage of the MASH DDSM, without using Dither shaping filter. Then, those Dither Signals are sent to the error cancellation logic (ECL), where they are eliminated by each other, avoiding appearing in the output spectrum. Simulation results show that, for the MASH DDSM, the new Dither adding method can guarantee a spur-free spectrum for all digital constant inputs without raising the noise floor.

  • WWIC - Spur-Free MASH DDSM with Eliminable Dither
    Lecture Notes in Computer Science, 2017
    Co-Authors: Yilong Liao, Xiangning Fan
    Abstract:

    This paper presents a new Dither adding method for multistage-noise-shaping (MASH) digital delta-sigma modulator (DDSM), to reduce the output spurious tones. In this method, the additive Dither Signal is added to two different nodes of any preceding stage of the MASH DDSM, without using Dither shaping filter. Then, those Dither Signals are sent to the error cancellation logic (ECL), where they are eliminated by each other, avoiding appearing in the output spectrum. Simulation results show that, for the MASH DDSM, the new Dither adding method can guarantee a spur-free spectrum for all digital constant inputs without raising the noise floor.

Dochain Denis - One of the best experts on this subject based on the ideXlab platform.

  • Robust sliding mode-based extremum-seeking controller for reaction systems via uncertainty estimation approach
    Wiley-Blackwell, 2017
    Co-Authors: Lara-cisneros Gerardo, Femat Ricardo, Dochain Denis
    Abstract:

    This paper deals with the design of a robust sliding mode-based extremum-seeking controller aimed at the online optimization of a class of uncertain reaction systems. The design methodology is based on an input– output linearizing method with variable-structure feedback, such that the closed-loop system converges to a neighborhood of the optimal set point with sliding mode motion. In contrast with previous extremumseeking control algorithms, the control scheme includes a dynamic modelling-error estimator to compensate for unknown terms related with model uncertainties and unmeasured disturbances. The proposed online optimization scheme does not make use of a Dither Signal or a gradient-based optimization algorithm. Practical stabilizability for the closed-loop system around to the unknown optimal set point is analyzed. Numerical experiments for two nonlinear processes illustrate the effectiveness of the proposed robust control scheme

  • Robust sliding mode‐based extremum‐seeking controller for reaction systems via uncertainty estimation approach
    John Wiley & Sons, 2017
    Co-Authors: Lara-cisneros Gerardo, Femat Flores, Alejandro Ricardo, Dochain Denis
    Abstract:

    "This paper deals with the design of a robust sliding mode‐based extremum‐seeking controller aimed at the online optimization of a class of uncertain reaction systems. The design methodology is based on an input–output linearizing method with variable‐structure feedback, such that the closed‐loop system converges to a neighborhood of the optimal set point with sliding mode motion. In contrast with previous extremum‐seeking control algorithms, the control scheme includes a dynamic modelling‐error estimator to compensate for unknown terms related with model uncertainties and unmeasured disturbances. The proposed online optimization scheme does not make use of a Dither Signal or a gradient‐based optimization algorithm. Practical stabilizability for the closed‐loop system around to the unknown optimal set point is analyzed. Numerical experiments for two nonlinear processes illustrate the effectiveness of the proposed robust control scheme.

Kenneth A. Cunefare - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Tangential Dither Signal on Friction Induced Oscillations in an SDOF Model
    Journal of Computational and Nonlinear Dynamics, 2007
    Co-Authors: Michael A. Michaux, Aldo A. Ferri, Kenneth A. Cunefare
    Abstract:

    This work examines how friction-induced oscillations in a traditional mass-on-a-moving-belt system are affected by high-frequency excitations, commonly referred to as Dither Signals. Two different friction laws are considered: a Stribeck friction law governed by a relationship that is cubic in the slip velocity, and an exponentially-based friction law that steadily decreases with slip velocity. Although in both cases the friction force has an initial negative slope versus relative velocity, their stability characteristics are quite different. In particular, it is shown that tangential Dither can either stabilize or destabilize an initially stable system, depending on the nature of the friction law, and on other system and Dither parameters. The behavior of the systems is studied through use of an averaging technique and through direct numerical simulation. The numerical study validates the stability predictions from the averaging method, and quantifies the partial-cancellation performance of tangential Dither.

  • Effect of burst‐modulated sinusoidal Dither waveforms on the effectiveness of Dither forces to eliminate friction‐induced oscillations
    Journal of the Acoustical Society of America, 2006
    Co-Authors: Jeff Badertscher, Kenneth A. Cunefare, Al Ferri, Michael M. Michaux
    Abstract:

    This paper examines the effectiveness of high‐frequency Dither‐cancellation techniques using burst‐modulated Signals. The classic single‐degree‐of‐freedom (SDOF), mass on moving belt, model is analyzed using the method of averaging and numerical integration of system dynamics. Two different friction laws are used to model the contact point, both exhibiting a negative friction coefficient‐velocity relationship. Recent results [M. Michaux and A. Ferri, Proceedings of IDETC05 Paper no. DETC2005‐84491 (2005)] found that sinusoidal Dither forces could stabilize or destabilize such a system, depending on the system and frictional characteristics as well as the Dither Signal amplitude and frequency. This paper extends this previous analysis to burst‐modulated sinusoidal Dither Signals. Earlier experimental research has shown burst‐modulated Dither Signals to be an effective method of suppressing automotive brake squeal. It is found that, for a given amplitude and frequency, burst Signals are also capable of stab...

  • Braking Impact of Normal Dither Signals
    Journal of Vibration and Acoustics, 2006
    Co-Authors: Jeff Badertscher, Kenneth A. Cunefare, Aldo A. Ferri
    Abstract:

    Dither control is a method of introducing high-frequency control efforts into a system to suppress a lower-frequency disturbance. One application of Dither control is the suppression of automotive brake squeal. Brake squeal is a problem that has plagued the automotive industry for years. Placing a piezoceramic stack actuator in the piston of a floating caliper brake creates an experimental normal Dither system. Many theoretical models indicate a reduction in the braking torque due to the normal Dither Signal. Using a Hertzian contact stiffness model, the loss in friction is due to lowering the average normal force. There are also theories that the Dither Signal eliminates the "stick-slip" oscillation causing an effective decrease in the friction force. Yet another theory indicates that the effective contact area is reduced, lowering the mean coefficient of friction. A particular approach considering a single-degree-of-freedom friction oscillator predicts a maximum friction reduction of 10%, occurring at the primary resonance of the system. This paper will concentrate on validating this claim by experimentally determining braking torque reduction for a variety of Dither control Signals. Several Dither control frequencies were chosen at system resonances, while others were chosen at frequencies most likely to provide control of the system. These frequencies were chosen based on previous squeal suppression research. The results indicate that Dither control frequencies at system resonances have a greater impact on the braking system's performance. In general, Dither control reduces braking torque by no more than 2%.

  • Braking Impact of Normal Dither Signals
    Dynamic Systems and Control Parts A and B, 2005
    Co-Authors: Jeff Badertscher, Kenneth A. Cunefare
    Abstract:

    Dither control is a method of introducing high frequency control efforts into a system to suppress a lower frequency disturbance. One application of Dither control is the suppression of automotive brake squeal. Brake squeal is a problem that has plagued the automotive industry for years. Placing a piezoceramic stack actuator in the piston of a floating caliper brake creates an experimental normal Dither system. Many theoretical models indicate a reduction in the braking torque due to the normal Dither Signal. Using a Hertzian contact stiffness model the loss in friction is due to lowering the average normal force. There are also theories that the Dither Signal eliminates the ‘stick-slip’ oscillation causing an effective decrease in the friction force. Yet another theory indicates that the effective contact area is reduced, lowering the mean coefficient of friction. A particular approach considering a single degree of freedom friction oscillator predicts a maximum friction reduction of 10%, occurring at the primary resonance of the system. This paper will concentrate on validating this claim by experimentally determining braking torque reduction for a variety of Dither control Signals. Several Dither control frequencies were chosen at system resonances, while others were chosen at frequencies most likely to provide control of the system. These frequencies were chosen based on previous squeal suppression research. The results indicate that Dither control frequencies at system resonances have a greater impact on the braking system’s performance. In general, Dither control reduces braking torque by no more than 2%.Copyright © 2005 by ASME

  • Effect of Tangential Dither Signal on Friction Induced Oscillations in the SDOF Model
    Volume 6: 5th International Conference on Multibody Systems Nonlinear Dynamics and Control Parts A B and C, 2005
    Co-Authors: Michael A. Michaux, Aldo A. Ferri, Kenneth A. Cunefare
    Abstract:

    This work examines how friction-induced oscillations are affected by high-frequency excitations, commonly referred to as Dither Signals. The traditional mass-on-moving-belt system is studied using two different friction models, both exhibiting a negative friction coefficient-velocity relationship. The method of averaging is implemented and compared with numerical simulations. It is shown that there is qualitative agreement between the two approaches, but there are significant quantitative differences. This study also demonstrates how tangential Dither is capable of suppressing friction-induced oscillations in many cases. However, it is also shown that Dither can destabilize an initially stable system in some circumstances.

Seng-chi Chen - One of the best experts on this subject based on the ideXlab platform.

  • Permanent magnet brushless motor field oriented control with Dither Signal injection
    2018 IEEE International Conference on Applied System Invention (ICASI), 2018
    Co-Authors: Seng-chi Chen, Elisabeth Tansiana Mbitu
    Abstract:

    The studies and application of Brushless Motor Field Oriented Control (FOC) with Dithering technique was built using real-time test platform in this work. Here, the Dither Signal was introduced to the system to eliminate the sustained oscillation called limit cycles which usually uncontrollable. To see the system performance, a Serial Communication Interface (SCI) was made to monitoring the digital Signal output. The experimental results show the ability of Dither injection Signal to remove the limit cycles at speed and electromagnetic field.

  • Nonlinearities stabilization using Dithering injection in permanent magnet DC motor system
    2018 IEEE International Conference on Applied System Invention (ICASI), 2018
    Co-Authors: Seng-chi Chen, Elisabeth Tansiana Mbitu
    Abstract:

    This paper presents the used of Dither Signal injection technique to stabilize the effect of nonlinearities in feedback control system. Various form of Dither has been proposed including square wave, sine wave, and triangle wave Dither. The analytical study of modified nonlinear element concept and simulation results show that square wave Dither required the minimum amplitude to eliminate the ‘hunt’ (self-oscillation) or limit cycles but the triangle wave Dither Signal has the best ability to eliminate the limit cycle because its actual of output Signal is closest to the reference Signal and smoothest than others.

  • Quench limit cycle using different Dither Signal in a servo motor system
    2016 International Conference on Advanced Materials for Science and Engineering (ICAMSE), 2016
    Co-Authors: Seng-chi Chen, Elisabeth Tansiana Mbitu
    Abstract:

    This paper concerns about the implementation of Dither Signals to quench the undesirable limit cycle was produced by saturation and backlash in a dc servo motor system. Various shapes of Dither Signals are injected into the system. Simulation results show that three Dither Signals evidently work differently. In this system, sinusoidal and saw-tooth Dither can quench the limit cycle better than square wave Dither.

  • Dither Signals with particular application to the control of windscreen wiper blades
    International Journal of Solids and Structures, 2006
    Co-Authors: Shun-chang Chang, Seng-chi Chen
    Abstract:

    This study verifies chaotic motion of an automotive wiper system, which consists of two blades driven by a DC motor via the two connected four-bar linkages and then elucidates a system for chaotic control. A bifurcation diagram reveals complex nonlinear behaviors over a range of parameter values. Next, the largest Lyapunov exponent is estimated to identify periodic and chaotic motions. Finally, a method for controlling a chaotic automotive wiper system will be proposed. The method involves applying another external input, called a Dither Signal, to the system. Some simulation results are presented to demonstrate the feasibility of the proposed method.

  • Experimental and analytical studies of the sinusoidal Dither Signal in a DC motor system
    Dynamics and Control, 1993
    Co-Authors: Pi-cheng Tung, Seng-chi Chen
    Abstract:

    In this article we are concerned with the implementation of a Dither Signal for a closed-loop DC motor system. Experimental studies show that the system contains two nonlinearities that are saturated with dead zone and backlash. Parameter estimation techniques are used to identify the unknown system parameters with special care due to the existence of system nonlinearities. An analytical method is then presented to deal with the closedloop DC motor system with two nonlinearities in the loop. Self-excited oscillations are found to exist in the system. A good correlation between the theoretical and experimental results indicates the success of the system identification and modelling process. Also the ability of Dither to quench the limit cycle is demonstrated from these results.

Jianho Chen - One of the best experts on this subject based on the ideXlab platform.

  • a new approach to direct torque control of induction motor drives for constant inverter switching frequency and torque ripple reduction
    IEEE Transactions on Energy Conversion, 2001
    Co-Authors: Yenshin Lai, Jianho Chen
    Abstract:

    In this paper, a new approach to the direct torque control (DTC) of induction motor drives is presented. In comparison with the conventional DTC methods, the inverter switching frequency is constant and is dramatically increased, requiring neither any increase of the sampling frequency, nor any high frequency Dither Signal. The well-developed space vector modulation technique is applied to inverter control in the proposed DTC-based induction motor drive system, thereby dramatically reducing the torque ripple and speed ripple. As compared to the existing DTC approach with constant inverter switching frequency, the presented new approach does not invoke any concept of deadbeat control, thereby dramatically reducing the computations. Experimental results are illustrated in this paper confirming that the proposed DTC method has the above-mentioned features even at the low speed range down to /spl plusmn/1 r/min.