2013 ACC ADRC Workshop - Presentations PDF Print E-mail
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Wednesday, 13 February 2013 05:54

 

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Presentations

Workshop participants will receive a set of viewgraphs that will be used at the workshop. The viewgraphs will be available for download. The following are the titles and abstract of  the presentations.


Foundation of Feedback Control: a Critical Examination

Zhiqiang Gao, Cleveland State University

Abstract: Recently there is a great self-reflection in the control community about the impacts and future of this discipline (Samad and Annaswamy, 2011). Critically important for the next phase of development of this field is to have a solid foundation (Astrom, 2012). What is left unsaid, however, is what this foundation is or if it needs to be solidified. This talk starts with the examination of these questions. In fact we intend to show that at the foot of this great body of knowledge there is much confusion, that the concept of feedback and feedback control need to be distinguished, as suggested in vein by Dr. Bode in 1960, and that to equate the science of control with that of feedback, an unexamined belief, is narrow minded. Through an exposition of history of ideas in automatic control, we let a picture of this discipline unfold that is rich and colorful. Recovering of these great ideas, we believe, will animate another round of furious growth in the science and engineering of automatic control.


Active Disturbance Rejection Control: From Concepts to Practice

Zhiqiang Gao, Cleveland State University.

Abstract: This presentation takes audience to revisit the long year history of intellectual and technological development where the idea seeded by J.V. Poncelet in 1829, rediscovered by G. V. Shipanov in 1939, and finally shaped into the key concept of ADRC by J. Han in 1989, was finally engineered, in the next twenty years, to the point where it starts to make an impact on industrial control. This is followed by a field survey of the scope of applications, its pros and cons comparing to existing technologies, and a few examples where ADRC brought new options to solve old problems. The goal is to help audience in making seamless integration of the ADRC concepts and the domain knowledge and skills of a particular engineering branch, and be able to take advantage of ADRC freely in solving the pressing problems of today.


On Methodology of Active Disturbance Rejection Control

Yi Huang, Wenchao Xue, Academy of Mathematics and Systems Science, Chinese Academy of Sciences

Abstract:After comparing the methodologies of ADRC and other methods for controlling uncertain systems, such as the adaptive control, robust control and disturbance observers based methods, etc., the talk illustrates that the essence in employing ADRC as a tool in dealing with largely uncertain processes, which may be nonlinear, time-varying and full of interconnected dynamics, is to first characterize the “total uncertainty” that affects the process output.


Theoretical Analysis ofActive Disturbance Rejection Control

Wenchao Xue, Yi Huang, Academy of Mathematics and Systems Science, Chinese Academy of Sciences

Abstract: The talk focuses on the mathematical analysis, performed by several groups of researchers over the years, that provides the theoretical foundation and explains the success and limitations of ADRC. Latest theoretical progress and open problems for future research will be discussed.


Active Disturbance Rejection and the Control of Differentially Flat Systems

Hebertt Sira Ramirez, Mechatronics Section, Centro de Investigaci´on y Estudios Avanzados del Instituto Polit´ecnico Nacional, Mexico.

Abstract: Differential flatness is a ubiquitous property for physical and engineering related dynamical systems. This property may be invoked to substantially simplify feedback controller design while trivializing trajectory planning tasks. Flatness is a property that spans most of the spectrum of deterministic controlled dynamical systems; starting with linear systems and continuing with nonlinear systems of mono-variable or multivariable types. It also includes a wide class of infinite dimensional systems such as: boundary controlled distributed parameter systems described by partial differential equations, delay differential systems and fractional derivative systems. This talk briefly introduces the differential flatness property to emphasize the use of efficient disturbance cancellation strategies in the control of uncertain dynamic systems of various kinds. We center around the advantageous combination of the paradigm of Active Disturbance Rejection Control and the differential flatness property. The aim is not only to simplify effective feedback control laws achieving stabilization or trajectory tracking tasks but, also, to achieve robustness with respect to modeled or un-modeled exogenous and endogenous disturbances. The talk contains a number of worked out simulation and experimental examples of physical and engineering flavor. 


On the Mathematical Proofs of Convergence of Active Disturbance Rejection Control

Bao-Zhu Guo, Academy of Mathematics and Systems Science, Academia Sinica, Beijing, China

Abstract: The active disturbance rejection control (ADRC), as a new control strategy in dealing with the large uncertainties, has been developed rapidly in the last two decades. Basically, the active disturbance rejection control is composed of three main parts: the differential tracking (TD); the  extended state observer (ESO); and the extended state observer-based feedback control (ADRC).  In these three parts, the extended state observer plays a crucial role toward the active disturbance rejection control.  ADRC covers at least stabilization and output regulation problems for very large class of  nonlinear uncertain systems. In this talk, the mathematical proofs of the convergence of three parts are presented.  The focus will be on the high gain parametrization with constant gain and time-varying one.


Disturbance Rejection in Space Applications: Problems and Solutions

Enrico Canuto, Politecnico di Torino, Dipartimento di Automatica e Informatica, Torino, Italy

Abstract: This talk characterizes and formulates the disturbance rejection problem that permeates most space applications, from scientific and drag-free space missions like GOCE, to European ‘Nanobalance’ interferometric thrust-stand, capable of sub-micronewton accuracy, and to the current studies on space formation control and planetary reentry. This entire field of space-related control problems is challenging because of the uncertainty inherent and the precision required, making it a great case study for disturbance rejection control. Design strategy and solutions are summarily introduced and discussed.


Embedded Model Control calls for disturbance modeling and rejection

Enrico Canuto, Politecnico di Torino, Dipartimento di Automatica e Informatica, Torino, Italy

Abstract: Embedded Model Control shows that a model-based control law must and can be kept intact in the case of uncertainty, if the controllable dynamics is complemented with suitable disturbance dynamics capable of real-time encoding the different uncertainties affecting the ‘embedded model’, i.e. the real-time model which is both the design source and the core of the control unit. The disturbance state is updated in real-time by an unpredictable input vector, referred to as noise, which can be estimated from the model error only, the latter being defined as the difference between plant and model output. The model-based control law can reject the predicted disturbance state in a similar way to active disturbance rejection. The uncertainty (or plant)-based design concerns the noise estimator, as the model error may convey uncertainty components (parameters, cross-couplings, neglected dynamics) which are command-dependent and thus are prone to destabilize the controlled plant, into the embedded model. Appropriate separation of the uncertainty components into low and high frequency domains by the noise estimator allows stability recovery and guarantee, and the rejection of the low frequency uncertainty components.


Active Disturbance Rejection in Internal Combustion Engines: Problems and Solutions

Hui Xie, State Key Lab. of Engine, Tianjin University

Abstract: The future of internal combustion engine is intimately connected to advanced control, as we continue to pursue the elusive perfection in efficiency, response time and pollution reduction. With highly nonlinear and uncertain dynamics, together with unpredictable external forces, internal combustion engine control at the core is disturbance rejection. The state of the art technology is grossly inadequate for future engines, making ADRC a strong alternative at this moment. The critical task for engine engineers is to combine their expertise of engine with advanced concepts such as ADRC to form an organic whole, from which new solutions and technologies arise. For example, the homogeneous charge compression ignition (HCCI) combustion is considered to be clean and high efficient, but suffers from the combustion timing control problem and is highly sensitivity to operation conditions, the variations of which become serious disturbances to the system. Initial results in active disturbance rejection of such disturbances show promising results. The research efforts in the last few years are summarized and discussed, so are the future research direction and plan.


Refined Anti-Disturbance Control in Aeronautical Engineering: Problems and Solutions

Lei Guo, school of Automation and Electronic Engineering, Beihang University, China

Abstract: In controlled plants in aeronautical engineering such as satellites, disturbances originate from multiple sources and can be represented by various formulations. The refined anti-disturbance control problem is addressed for such systems with multiple disturbances. Composite Hierarchical anti-disturbance method is formulated to reject and attenuate the different disturbances respectively and simultaneously. A few case studies for navigation and control problems are provided and illustrated.


Linear Active Disturbance Rejection Controllers (LADRC) for Boiler-Turbine Units

Wen Tan, School of Control and Computer Engineering, North China Electric Power University.

Abstract: Linear active disturbance rejection control (LADRC) is shown to be a simple and effective method as a substitute of conventional PID control. Nevertheless, the tuning of the LADRC parameters needs some experience, especially for multivariable systems. Boiler-turbine units are widely used in power generation industry, and are typical multivariable systems with strong coupling, nonlinearity, large time delay and large inertia. In this paper, an LADRC scheme is proposed for boiler-turbine units which compromise a decoupling compensator and two SISO linear active disturbance rejection controllers. The compensator helps reduce the strong coupling between the two outputs and two LADRCs further reduce the external disturbances and model uncertainties. Since LADRC can estimate the disturbances via extended state observer (ESO), it will eliminate the disturbance quickly independent of the accurate mathematical model of the units. Simulation results show that the LADRC structure for boiler-turbine units can achieve good decoupling and good disturbance rejection with robustness, and it is easy to tune and implement in practice.


Active Disturbance Rejection in a Lower-limb Rehabilitation Manipulator

Rafal Madonski, Poznan University of Technology, Poland

Abstract:Rehabilitation robotics is gradually becoming a standard in working side by side with the physiotherapists during their everyday routine. The main task of the rehabilitation manipulators, besides their obvious goal of preventing complications due to posttraumatic or postoperative therapy, is to be able to perform various physiotherapeutic trainings. Such sets of exercises based on various types of muscle contraction are performed by the patients to avoid the possible effect of muscular dystrophy during the recovery period. The main two trainings include isometric and isotonic exercises.

The above trainings imply a high level of precision, repeatability, and user safety that a particular robotic rehabilitation manipulator has to provide. Hence, it is crucial to use a reliable control approach in order to ensure the desired system behavior in uncertain working conditions (nonlinear and time-varying physical phenomena, changeable external forces, unmeasured noises, etc.). Additionally, finding an accurate mathematical representation of the considered complex robotic system, that could be further used for the controller synthesis, is problematic and time-consuming. However, this problem can be solved in some cases using robust control strategies. Algorithms of this class provide satisfactory system performance even in the presence of acting perturbation. An interesting class of robust techniques are methods based on simultaneous estimation and rejection of disturbances in the plant. An example of such techniques is Active Disturbance Rejection Control (or ADRC).

Hence, the presentation is focused on analyzing the applicability of the ADRC method in controlling position, velocity, and force of the manipulator link. Such hybrid controller is verified in both simulations and experiments, conducted on a model of a knee-rehabilitation system, which is a flexible joint manipulator with changeable stiffness. The effectiveness of the proposed controller is also examined through the execution of the isometric and isotonic trainings. Other aspects of the considered ADRC-based control approach, such as tuning methodology, parametric robustness, or comparison tests, are also covered by the presentation.

This work is supported by grant NR 13-0028/2011, funded by the Polish Ministry of Science and Higher Education.


On The Unity of Decoupling Control and Active Disturbance Rejection, with Applications in Process Control

Qing Zheng, Electrical and Computer Engineering Department, Gannon University

Abstract: In this talk, a unique dynamic disturbance decoupling control (DDC) strategy, based on the active disturbance rejection control (ADRC) framework, is presented. With the proposed method, it is shown that a largely unknown square multivariable system is readily decoupled by actively estimating and rejecting the effects of both the internal plant dynamics and external disturbances. By requiring as little information on plant model as possible, the intention is to make the new method practical. The stability analysis shows that both the estimation error and the closed-loop tracking error are bounded and the error upper bounds monotonously decrease with the bandwidths. Simulation results obtained on two chemical process problems show excellent performance in the presence of significant unknown disturbances and unmodeled dynamics. The ADRC based DDC approach proves to be a great fit for the highly nonlinear and multivariable chemical processes.

Recently, the DDC design strategy has been put under rigorous test at Parker Hannifin Parflex hose extrusion plant. It was implemented in programmable logic control (PLC) code for temperature regulation in the volumetric flow of a polymer single-screw extruder. Across multiple production lines for over eight months, the product performance capability index (Cpk) was improved by 30 percent and energy consumption was reduced over 50 percent. The production line data demonstrates that ADRC based DDC strategy is a transformative control technology with great potentials in streamline factory operations, saving energy and improving quality, all at the same time. The simulation tests and production line data show the unity of decoupling control and active disturbance rejection.


Application of Active Disturbance Rejection Control in Superconducting Radio Frequency Cavities of Modern Linear Particle Accelerators

Shen Zhao, Facility for Rare Isotope Beams and National Superconducting Cyclotron Laboratory, Michigan State University

Abstract: Superconducting radio frequency (SRF) cavities are key components of modern linear particle accelerators. The National Superconducting Cyclotron Laboratory (NSCL) is building a 3 MeV/u re-accelerator (ReA3) using SRF cavities. The ongoing Facility for Rare Isotope Beams (FRIB) project at NSCL requires even more (over 340) SRF cavities. Lightly loaded SRF cavities have very small bandwidths (high Q) making them very sensitive to mechanical perturbations whether external or self-induced. Additionally, some cavity types exhibit mechanical responses to perturbations that lead to high-order non-stationary transfer functions resulting in very complex control problems. In this talk, how the microphonics problem is mitigated using a seemingly ideal solution, known as Active Disturbance Rejection Control (ADRC), will be introduced. The test results on ReA3 cavities have shown two to four times of performance improvement over the industrial standard PID solution. Recent work on self-excited loop, beam loading and digital implementation of ADRC in FPGA, and future work on dealing with amplifier nonlinearity and improving tuner control will be discussed as well.

Last Updated on Thursday, 14 November 2013 17:54
 
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