Robust and Decentralized Control of Web Winding Systems

This research addresses the velocity and tension regulation problems in web handling, including those found in the single element of an accumulator and those in the large-scale system settings. A continuous web winding system is a complex large-scale interconnected dynamics system with numerous tension zones to transport the web while processing it. A major challenge in controlling such systems is the unexpected disturbances that propagate through the system and affect both tension and velocity loops along the way. To solve this problem, a unique active disturbance rejection control (ADRC) strategy is proposed. Simulation results show remarkable disturbance rejection capability of the proposed control scheme in coping with large dynamic variations commonly seen in web winding systems. Another complication in web winding system stems from its large-scale and interconnected dynamics which makes control design difficult. This motivates the research in formulating a novel robust decentralized control strategy. The key idea in the proposed approach is that nonlinearities and interactions between adjunct subsystems are regarded as perturbations, to be estimated by an augmented state observer and rejected in the control loop, therefore making the local control design extremely simple. The proposed decentralized control strategy was implemented on a 3-tension-zone web winding processing line. Simulation results show that the proposed control method leads to much better tension and velocity regulation quality than the existing controller common in industry. Finally, this research tackles the challenging problem of stability analysis. Although ADRC has demonstrated the validity and advantage in many applications, the rigorous stability study has not been fully addressed previously. To this end, stability characterization of ADRC is carried out in this work. The closed-loop system is first reformulated, resulting in a form that allows the application of the well established singular perturbation method. Based on the decom

Robust and Decentralized Control of Web Winding Systems

This research addresses the velocity and tension regulation problems in web handling, including those found in the single element of an accumulator and those in the large-scale system settings. A continuous web winding system is a complex large-scale interconnected dynamics system with numerous tension zones to transport the web while processing it. A major challenge in controlling such systems is the unexpected disturbances that propagate through the system and affect both tension and velocity loops along the way. To solve this problem, a unique active disturbance rejection control (ADRC) strategy is proposed. Simulation results show remarkable disturbance rejection capability of the proposed control scheme in coping with large dynamic variations commonly seen in web winding systems. Another complication in web winding system stems from its large-scale and interconnected dynamics which makes control design difficult. This motivates the research in formulating a novel robust decentralized control strategy. The key idea in the proposed approach is that nonlinearities and interactions between adjunct subsystems are regarded as perturbations, to be estimated by an augmented state observer and rejected in the control loop, therefore making the local control design extremely simple. The proposed decentralized control strategy was implemented on a 3-tension-zone web winding processing line. Simulation results show that the proposed control method leads to much better tension and velocity regulation quality than the existing controller common in industry. Finally, this research tackles the challenging problem of stability analysis. Although ADRC has demonstrated the validity and advantage in many applications, the rigorous stability study has not been fully addressed previously. To this end, stability characterization of ADRC is carried out in this work. The closed-loop system is first reformulated, resulting in a form that allows the application of the well established singular perturbation method. Based on the decom

Linear active disturbance rejection control of waste heat recovery systems with organic Rankine cycles

In this paper, a linear active disturbance rejection controller is proposed for a waste heat recovery system using an organic Rankine cycle process, whose model is obtained by applying the system identification technique. The disturbances imposed on the waste heat recovery system are estimated through an extended linear state observer and then compensated by a linear feedback control strategy. The proposed control strategy is applied to a 100 kW waste heat recovery system to handle the power demand variations of grid and process disturbances. The effectiveness of this controller is verified via a simulation study, and the results demonstrate that the proposed strategy can provide satisfactory tracking performance and disturbance rejection

Control of high precision roll-to-roll manufacturing systems

The flexible electronic industry has been growing rapidly over the past decade. One of the barriers to commercialization is the high cost of manufacturing micro- and nano-scale printed electronics using traditional methods. Roll-to-roll manufacturing has been identified as a method of achieving low cost and high throughput. A dynamic model of a roll-to-roll system is presented. In all roll-to-roll applications, tension and velocity must be accurately controlled to desired reference trajectories to ensure a quality finished product. Additionally, a registration error model is presented for the control design. Minimization of the registration is the primary objective for flexible electronics, but web tension and velocity cannot be neglected. The model is needed in order to formulate a methodology that can simultaneously control tension, velocity, and registration error in the presence of disturbances. Micro and nano-scale features are susceptible to damage from friction between the web and the roller. Therefore, tension estimation techniques is highly desired to eliminate load cells from the system. The reduced order observer, extended Kalman filter, and an unknown input observer is presented. Development of tension and velocity control strategies have historically revolved around decentralized SISO control schemes. In order to achieve higher precision, a centralized MIMO strategy is proposed and compared to decentralized SISO. The advantage of the MIMO controller improved handling of the tension velocity coupling in roll-to-roll systems. The tension observer is introduced to the control design and evaluated for overall effectiveness. In simulation, the centralized MIMO control with the unknown input observer demonstrated superior tension and velocity tracking as well as minimal registration error. Development of the proposed MIMO control strategy can enable flexible electronic fabrication using roll-to-roll manufacturing.Mechanical Engineerin

Enabling hybrid process metrology in roll-to-roll nanomanufacturing: design of a tip-based tool for topographic sampling on flexible substrates

This work seeks to demonstrate the efficacy of a novel approach for topography measurement of nano-scale structures fabricated on a flexible substrate in a roll-to-roll (R2R) fashion. R2R manufactured products can be extremely cost competitive compared to more traditional, silicon wafer or glass panel based nanofabrication solutions, in addition to the unique and often desirable mechanical properties inherent to flexible substrates. As such, flexible nanomanufacturing is an area of immense research interest. However, despite the significant potential of these products for a variety of applications, developing manufacturing systems from lab-scale prototypes to pilot- or high volume manufacturing (HVM) has often proven both difficult and infeasibly expensive as research investment and achievable process yield limit advancement. One of the most significant capability gaps in current art, and roadblocks on the path towards adoption of R2R nanomanufacturing, is the lack of high-throughput, nanometer-scale metrology for process development, real-time control, and yield enhancement. This dissertation presents the design of a tip-based measurement tool implementing atomic force microscope (AFM) probes manufactured with a micro-electro-mechanical system (MEMS) approach to the challenge of sub-micron topography measurement which is also compatible with R2R manufacturing on flexible substrates. A proof-of-concept prototype tool with subsystems to regulate a flexible web, isolate and position the atomic force microscope probe, and measure features on the substrate, all coordinated by a real-time embedded control system, was designed and fabricated. The positioning subsystem was evaluated dynamically to ensure initial design requirements were met, and stationery, step-and-scan results were presented. However, to wholly meet this extent need for in-line R2R metrology, a system capable of atomic force microscope scanning despite a continuous, non-zero substrate velocity is required - any regular stoppage of the web in a R2R process all but dooms economically viable production throughput. Refinement and redesign of the proof-of-concept tool was driven by new system requirements to meet this goal, in addition to lessons learned from the initial prototype. Improvements focused on upgrading the web handling spindle design and mechatronics, tool power electronics, moving structures, and control algorithms used for high-speed synchronous positioning of the atomic force microscope and web. The culmination of this work will serve to introduce a new measurement framework which may be used to accelerate and enable future research in R2R manufacturing of nanofeatured products.Mechanical Engineerin

A Transformative Process Control Solution

Knowing that a technology invented almost hundred years ago (PID controller) is still dominating industrial process control, a historical review was done to understand how the control field evolved. Model dependency and high level of mathematics appear as the main reasons that prevent other technologies from penetrating the engineering practice. A relatively novel methodology introduced by J. Han in 1998 called Active Disturbance Rejection Control (ADRC) came with characteristics that matches process control needs and restrictions on model dependency. This study will present a transformative solution for process control based on that. The control algorithm is designed and discretized for digital implementation in PLC or DSC. The tuning process is explained in a logical and intuitive way based on time and frequency domain characteristics. The idea was to use the language familiar to industry practitioners. To show its applicability, a case study was done for server’s temperature control; and the results show energy savings of 30% when compared to PID controllers. This solution is not yet optimal, since it is generally applicable for a wide range of processes, but it aims to be a step further in process control

A Transformative Process Control Solution

Knowing that a technology invented almost hundred years ago (PID controller) is still dominating industrial process control, a historical review was done to understand how the control field evolved. Model dependency and high level of mathematics appear as the main reasons that prevent other technologies from penetrating the engineering practice. A relatively novel methodology introduced by J. Han in 1998 called Active Disturbance Rejection Control (ADRC) came with characteristics that matches process control needs and restrictions on model dependency. This study will present a transformative solution for process control based on that. The control algorithm is designed and discretized for digital implementation in PLC or DSC. The tuning process is explained in a logical and intuitive way based on time and frequency domain characteristics. The idea was to use the language familiar to industry practitioners. To show its applicability, a case study was done for server’s temperature control; and the results show energy savings of 30% when compared to PID controllers. This solution is not yet optimal, since it is generally applicable for a wide range of processes, but it aims to be a step further in process control

A Robust Decentralized Load Frequency Controller for Interconnected Power Systems

A novel design of a robust decentralized load frequency control (LFC) algorithm is proposed for an inter-connected three-area power system, for the purpose of regulating area control error (ACE) in the presence of system uncertainties and external disturbances. The design is based on the concept of active disturbance rejection control (ADRC). Estimating and mitigating the total effect of various uncertainties in real time, ADRC is particularly effective against a wide range of parameter variations, model uncertainties, and large disturbances. Furthermore, with only two tuning parameters, the controller provides a simple and easy-to-use solution to complex engineering problems in practice. Here, an ADRC-based LFC solution is developed for systems with turbines of various types, such as non-reheat, reheat, and hydraulic. The simulation results verified the effectiveness of the ADRC, in comparison with an existing PI-type controller tuned via genetic algorithm linear matrix inequalities (GALMIs). The comparison results show the superiority of the proposed solution. Moreover, the stability and robustness of the closed-loop system is studied using frequency-domain analysis

Robotics Control Using Active Disturbance Rejection Control

Conventional robotics control has been set in stone since the sixties. The world has been waiting too long for a new age of control to change the world of Robotics. Active Disturbance Rejection Control (ADRC) is a newly reformed Control methodology. It has been used, in very limited applications, as a replacement for PID control. In this thesis, I will cover the different aspects of the kinematics and dynamics of a robotic manipulator. I will also examine the feasibility of using ADRC to control a robotic manipulator. To explain ADRC, a simple example that demonstrates the concepts and theory of Active Disturbance Rejection Control will be discussed. Using this example, the establishment of relevance to the mathematical module of a rotary prismatic robotic manipulator will be accomplished. A control system for the module using Matlab software and mathematical computations will be implemente

Robotics Control Using Active Disturbance Rejection Control

Conventional robotics control has been set in stone since the sixties. The world has been waiting too long for a new age of control to change the world of Robotics. Active Disturbance Rejection Control (ADRC) is a newly reformed Control methodology. It has been used, in very limited applications, as a replacement for PID control. In this thesis, I will cover the different aspects of the kinematics and dynamics of a robotic manipulator. I will also examine the feasibility of using ADRC to control a robotic manipulator. To explain ADRC, a simple example that demonstrates the concepts and theory of Active Disturbance Rejection Control will be discussed. Using this example, the establishment of relevance to the mathematical module of a rotary prismatic robotic manipulator will be accomplished. A control system for the module using Matlab software and mathematical computations will be implemente