The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Shiming Deng - One of the best experts on this subject based on the ideXlab platform.
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Multivariable Control of indoor air temperature and humidity in a direct expansion dx air conditioning a c system
Building and Environment, 2009Co-Authors: Shiming DengAbstract:Abstract Controlling indoor humidity at an appropriate level is very important since this affects occupants' thermal comfort and indoor air quality (IAQ). The paper presents an investigation on developing a multi-input multi-output (MIMO) Control strategy for simultaneously Controlling the indoor air temperature and humidity by varying the speeds of both compressor and supply fan in an experimental DX A/C system. The MIMO-based Controller was designed based on the linearized dynamic model of the experimental DX A/C system. The Linear Quadratic Gaussian (LQG) technique was used in designing the MIMO-based Controller. The Controllability tests with respect to both the disturbance rejection capability and the command following capability were carried out to assess the Control performance of MIMO Controller. The results of disturbance rejection capability test showed that the MIMO Control strategy can effectively maintain the indoor air temperature and humidity to their respective settings after an unmeasured heat load disturbance was imposed by simultaneously varying speeds of both the compressor and the supply fan of the DX A/C system. Furthermore, in the command following capability test for indoor air temperature, the test results showed that the indoor air temperature can be Controlled to its new setting while indoor humidity remained unchanged. Similar test results were also observed in the command following capability test for indoor humidity. Therefore, the MIMO Controller developed can effectively Control indoor air temperature and humidity simultaneously by varying compressor speed and supply fan speed of the DX A/C system. Compared to the previous related studies using conventional on–off Control method or single-input single-output (SISO) Control strategy, which can only effectively Control either air temperature or relative humidity, the MIMO Controller can simultaneously Control the indoor air temperature and humidity with adequate Control sensitivity and accuracy. The application of MIMO Control strategy developed can be extended to other HVAC systems in the future to improve their operating performance and energy efficiency.
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Multivariable Control oriented modeling of a direct expansion dx air conditioning a c system
International Journal of Refrigeration-revue Internationale Du Froid, 2008Co-Authors: Shiming DengAbstract:A dynamic mathematical model for a DX A/C system has been developed. The dynamic model, written in state-space representation which was suitable for designing Multivariable Control, was linearized at steady state operating points. The linearized model has been validated by comparing the model simulation results with the experimental data obtained from an experimental DX A/C system. The simulated results agreed well with the experimental data, suggesting that the model developed was able to capture the transient characteristics of the DX A/C system modeled. It is expected that the model developed can be useful in designing a multi-input multi-output (MIMO) Controller to simultaneously Control indoor air temperature and humidity in a space served by a DX A/C system.
Karl Henrik Johansson - One of the best experts on this subject based on the ideXlab platform.
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the quadruple tank process a Multivariable laboratory process with an adjustable zero
IEEE Transactions on Control Systems and Technology, 2000Co-Authors: Karl Henrik JohanssonAbstract:A Multivariable laboratory process that consists of four interconnected water tanks is presented. The linearized dynamics of the system have a Multivariable zero that is possible to move along the real axis by changing a valve. The zero can be placed in both the left and the right half-plane. In this way the quadruple-tank process is ideal for illustrating many concepts in Multivariable Control, particularly performance limitations due to Multivariable right half-plane zeros. The location and the direction of the zero have an appealing physical interpretation. Accurate models are derived from both physical and experimental data and decentralized Control is demonstrated on the process.
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teaching Multivariable Control using the quadruple tank process
Conference on Decision and Control, 1999Co-Authors: Karl Henrik Johansson, Alexander Horch, O Wijk, Anders HanssonAbstract:A Multivariable laboratory process is presented together with its use in a graduate Control course. The process is called the quadruple-tank process and demonstrates a Multivariable level Control problem. The Multivariable zero dynamics of the system can be made both minimum phase and nonminimum phase by simply changing a valve. This makes the quadruple-tank process suitable for illustrating many concepts in linear and nonlinear Multivariable Control. In the paper some of these are described together with the basic setup of the process. Two computer exercises and one laboratory exercise have been developed as part of a course in Multivariable and nonlinear Control. These are detailed and some experience from the course is presented.
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relay feedback and Multivariable Control
PhD Thesis TFRT-1048; (1997), 1997Co-Authors: Karl Henrik JohanssonAbstract:This doctoral thesis treats three issues in Control engineering related to relay feedback and Multivariable Control systems. Linear systems with relay feedback is the first topic. Such systems are shown to exhibit several interesting behaviors. It is proved that there exist multiple fast relay switches if and only if the sign of the first non-vanishing Markov parameter of the linear system is positive. It is also shown that these fast switches can appear as part of a stable limit cycle. A linear system with pole excess one or two is demonstrated to be particularly interesting. Stability conditions for these cases are derived. It is also discussed how fast relay switches can be approximated by sliding modes. Performance limitations in linear Multivariable Control systems is the second topic. It is proved that if the top left submatrices of a stable transfer matrix have no right half-plane zeros and a certain high-frequency condition holds, then there exists a diagonal stabilizing feedback that makes a weighted sensitivity function arbitrarily small. Implications on Control structure design and sequential loop-closure are given. A novel Multivariable laboratory process is also presented. Its linearized dynamics have a transmission zero that can be located anywhere on the real axis by simply adjusting two valves. This process is well suited to illustrate many issues in Multivariable Control, for example, Control design limitations due to right half-plane zeros. The third topic is a combination of relay feedback and Multivariable Control. Tuning of individual loops in an existing Multivariable Control system is discussed. It is shown that a specific relay feedback experiment can be used to obtain process information suitable for performance improvement in a loop, without any prior knowledge of the system dynamics. The influence of the loop retuning on the overall closed-loop performance is derived and interpreted in several ways.
Yingzhi Zeng - One of the best experts on this subject based on the ideXlab platform.
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Multivariable Control of anaerobic reactor by using external recirculation and bypass ratio
Journal of Chemical Technology & Biotechnology, 2008Co-Authors: Shengjing Mu, Yingzhi Zeng, Ping WuAbstract:BACKGROUND: The operation of a high-rate anaerobic process usually suffers from problems of high sensitivity to disturbances arising from environmental and operational factors. Application of advanced process Controls is an efficient approach to enhancing process robustness and stability. RESULTS: A Multivariable linear quadratic tracking (LQT) approach to the output tracking of an anaerobic reactor was proposed, using external recirculation-to-feed ratio (Rr) and external bypass-to-feed ratio (Rs). The anaerobic digestion process is described by a distributed parameter model with a two-step (acidogenesis-methanization) kinetics. A state space model was developed using linear approximations of the nonlinear terms, and an output tracking method was developed combining linear quadratic tracking (LQT) and an integral action. CONCLUSION: Simulations show that, compared with the normal LQT method and proportional-integral (PI) Controller, using both Rr and Rs and a conventional dilution rate (Dr) based single variable PI Controller, the proposed Control approach achieved better results in both output set-point tracking and stabilization of effluent quality under influent disturbances and model-process mismatch. The new Control strategy also had the advantage of using less storage capacity. Copyright © 2008 Society of Chemical Industry
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Multivariable Control of anaerobic reactor by using external recirculation and bypass ratio
Journal of Chemical Technology & Biotechnology, 2008Co-Authors: Yingzhi ZengAbstract:BACKGROUND: The operation of a high-rate anaerobic process usually suffers from problems of high sensitivity to disturbances arising from environmental and operational factors. Application of advanced process Controls is an efficient approach to enhancing process robustness and stability. RESULTS: A Multivariable linear quadratic tracking (LQT) approach to the output tracking of an anaerobic reactor was proposed, using external recirculation-to-feed ratio (Rr) and external bypass-to-feed ratio (Rs). The anaerobic digestion process is described by a distributed parameter model with a two-step (acidogenesis-methanization) kinetics. A state space model was developed using linear approximations of the nonlinear terms, and an output tracking method was developed combining linear quadratic tracking (LQT) and an integral action. CONCLUSION: Simulations show that, compared with the normal LQT method and proportional-integral (PI) Controller, using both Rr and Rs and a conventional dilution rate (Dr) based single variable PI Controller, the proposed Control approach achieved better results in both output set-point tracking and stabilization of effluent quality under influent disturbances and model-process mismatch. The new Control strategy also had the advantage of using less storage capacity. Copyright © 2008 Society of Chemical Industry
Fang Fang - One of the best experts on this subject based on the ideXlab platform.
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generalized predictive Control applied in waste heat recovery power plants
Applied Energy, 2013Co-Authors: Jianhua Zhang, Yeli Zhou, Ying Li, Fang FangAbstract:A Multivariable Control strategy is needed to ensure high efficiency and load-following capability in the operation of waste heat recovery power plants. In this paper, a generalized predictive Controller is proposed for a waste heat recovery process operating on an organic Rankine cycle. The simulation results show that the proposed Control strategy not only can achieve good transient and steady response along with decoupling performance, but also can obtain satisfactory disturbance rejection performance.
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dynamic modeling and Multivariable Control of organic rankine cycles in waste heat utilizing processes
Computers & Mathematics With Applications, 2012Co-Authors: Jianhua Zhang, Wenfang Zhang, Fang FangAbstract:In this paper, the dynamics of organic Rankine cycles (ORCs) in waste heat utilizing processes is investigated, and the physical model of a 100 kW waste heat utilizing process is established. In order to achieve both transient performance and steady-state energy saving, a Multivariable Control strategy for the waste heat recovery system is proposed by incorporating a linear quadratic regulator (LQR) with a PI Controller. Simulations demonstrate that the proposed strategy can obtain satisfactory performance.
Takeo Kanade - One of the best experts on this subject based on the ideXlab platform.
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design and flight testing of a gain scheduled h sub spl infin loop shaping Controller for wide envelope flight of a robotic helicopter
American Control Conference, 2003Co-Authors: M La Civita, G Papageorgiou, William C Messner, Takeo KanadeAbstract:Complex future missions in civilian and military scenarios will require robotic helicopters to have Controllers that exploit their full dynamic capabilities. The absence of high fidelity simulation models has prevented the use of well established Multivariable Control techniques for the design of high-bandwidth full-flight-envelope Control systems. Existing model-based Controllers are of low bandwidth and cover only small portions of the vehicle's flight envelope. In this paper we present the results of the synergistic use of high-fidelity integrated modeling strategies, robust Multivariable Control techniques, and classical gain scheduling for the rapid and reliable design of a high-bandwidth full-flight-envelope Controller for robotic helicopters. We implemented and flight tested a gain-scheduled H/sub /spl infin// loop shaping Controller on the Carnegie Mellon University (CMU) Yamaha R-50 robotic helicopter. This gain-scheduled H/sub /spl infin// loop shaping Controller is the first of its kind to be flight tested on a helicopter (manned or unmanned). During the flight tests, the CMU R-50 flew moderate to high-speed maneuvers. We believe that our modeling/Control approach delivers Controllers that exploit the full dynamic capability of the airframe and thus are ready to be used by higher level navigation systems for complex autonomous missions.
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integrated modeling and robust Control for full envelope flight of robotic helicopters
International Conference on Robotics and Automation, 2003Co-Authors: M La Civita, G Papageorgiou, William C Messner, Takeo KanadeAbstract:To accomplish successfully the complex future mission in civilian and military scenarios, robotic helicopters need to have Controllers that exploit their full dynamic capabilities. The absence of high-fidelity simulation models has prevented the use of well established Multivariable Control techniques for the design of high-bandwidth full-flight-envelope Control systems. Existing model-based Controllers are of low bandwidth and cover only small portions of the vehicle's flight envelope. In this paper we present the results of the synergistic use of high-fidelity integrated modeling strategies, robust Multivariable Control techniques, and classical gain scheduling for the rapid and reliable design of high-bandwidth full-flight envelope Controllers for robotic helicopters. We implemented and flight tested a gain-scheduled H/sub /spl infin// loop-shaping Controller on the Carnegie Mellon University (CMU) Yamaha R-50 robotic helicopter. During the flight tests, the CMU R-50 flew several high-speed maneuvers. We believe that our modeling/Control approach quickly delivers Controllers that exploit the full dynamic capabilities of the airframe and thus are ready to be used by higher level navigation systems for complex autonomous missions.
