Yuping Li

Delft University Of Technology, Delft, South Holland, Netherlands

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Publications (14)8.58 Total impact

  • Source
    Yuping Li, B. De Schutter
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    ABSTRACT: In the distant-downstream control of irrigation channels, the interactions between pools and the internal time-delay for water to travel from upstream to downstream, impose limitations on global performance, i.e. there exist propagation of water level errors and amplification of flows over gates in the upstream direction. This paper analyses these coupling properties for a string of identical pools, both with identical feedback controllers and with non-identical feedback controllers. The definition of string stability in terms of bounded water level errors and bounded flows is given. It is shown that for a string of infinite number of pools, string stability cannot be achieved by decentralised distant-downstream feedback control. However, for a string of finite number of pools, a better global performance can be achieved by non-identical feedback controllers such that the closed-loop bandwidths of the subsystems increase from downstream to upstream.
    Decision and Control (CDC), 2010 49th IEEE Conference on; 01/2011
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    Yuping Li, Bart De Schutter
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    ABSTRACT: For a string of pools with distant-downstream control, the internal time-delay for water transport from upstream to downstream does not only limit the local control performance of regulating water-levels at setpoints and rejecting offtake disturbances in each pool, but also impacts the global performance of managing the water-level error propagation and attenuating the amplification of control actions in the upstream direction. A distributed control scheme that inherits the interconnection structure of the plant is investigated. It is shown that the decoupling terms in the controller help to improve global closed-loop performance by decreasing the low-frequency gain of the closed-loop coupling. Moreover, the decoupling terms compensate for the influence of the time-delay by imposing extra phase lead-lag compensation in the mid-frequency range on the closed-loop coupling function.
    Control Engineering Practice - CONTROL ENG PRACTICE. 01/2011; 19(10):1147-1156.
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    Yuping Li, B. De Schutter
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    ABSTRACT: For a string of pools with distant-downstream control, the internal time-delay for water transport from upstream to downstream not only limits the local control performance of regulating water-levels at setpoints and rejecting offtake disturbances in each pool, but also impacts the global performance of managing the water-level error propagation and attenuating the amplification of control actions in the upstream direction. A distributed control scheme which inherits the interconnection structure of the plant is studied. It is shown that the decoupling terms in the controller helps to improve global closed-loop performance by decreasing the low-frequency gain of the closed-loop coupling. Moreover, they compensate for the influence of the time-delay by imposing extra phase lead-lag compensation in the mid-frequency range on the closed-loop coupling function.
    Control Applications (CCA), 2010 IEEE International Conference on; 10/2010
  • Source
    Yuping Li, B. De Schutter
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    ABSTRACT: In the control of irrigation channels, there exists a tradeoff between the local performance of regulating the water-level in each pool to a given setpoint and rejecting offtake disturbances, on the one hand, and decoupling between pools, on the other. Such a tradeoff is well managed by a distributed control that inherits the interconnection structure of the plant. Furthermore, to decrease the water-level deviation from its setpoint in response to large offtakes, i.e. to improve the transient response of the local closed-loop system, the knowledge of the offtakes can be fed forward. This paper explores the designing of a feedforward compensator to improve local control performance while maintaining the good management of closed-loop coupling between pools by distributed control.
    American Control Conference (ACC), 2010; 08/2010
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    J. Alende, Yuping Li, M. Cantoni
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    ABSTRACT: A {0,1} linear program is proposed for scheduling fixed-profile requests to load a dynamical system. The problem involves organizing requested load across time, without modifying the load profile of individual requests, while satisfying constraints on the transient response of the system to change in the load. A time representation of the load is developed and delivery delays, being the differences between requested and scheduled start times, are introduced as the decision variables. Given a linear discrete-time state-space model of the dynamical system and an objective of minimizing a measure of overall delivery delay, the problem is initially formulated as a mixed-integer non-linear program. This is then shown to be equivalent to a more tractable {0,1} linear program. The main ideas are motivated by and applied to the problem of scheduling water off-takes from an automated irrigation channel.
    Decision and Control, 2009 held jointly with the 2009 28th Chinese Control Conference. CDC/CCC 2009. Proceedings of the 48th IEEE Conference on; 01/2010
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    ABSTRACT: The problem of fixed-profile load scheduling is considered for large-scale irrigation channels. Based on the analysis of the special structure of a channel under decentralised control, a predictive model is built on a pool-by-pool basis and a decomposition strategy of the scheduling problem is provided. The decomposition avoids excessive memory requirements in building the predictive model of the controlled plant and solving the formulated optimisation problem.
    Proceedings of the IEEE International Conference on Control Applications, CCA 2010, Yokohama, Japan, September 8-10, 2010; 01/2010
  • Yuping Li, M. Cantoni
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    ABSTRACT: For a class of (marginally) stable linear plants with distributed structure, it is shown that a well-known anti-windup/bumpless-transfer scheme can be applied in a correspondingly distributed fashion. This is desirable, for example, when the feedback controller is also designed to respect the distributed structure of the plant. To illustrate the main ideas, an anti-windup compensator is designed for an open-water channel control system. Both simulation and field test results are presented.
    Decision and Control, 2007 46th IEEE Conference on; 01/2008
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    ABSTRACT: Irrigation networks of open-water channels are used throughout the world to support agricultural activity. By and large, these networks are managed in open loop. To achieve closed-loop water distribution management, it is necessary to augment these civil engineering systems with an appropriate information infrastructure-sensors, actuators, information processing, and communication resources. Recent pilot projects in Australia demonstrate the significant potential of closed-loop management, which can yield a significant improvement in the quality of service, while achieving improved water distribution efficiency. This paper focuses on the modelling and closed-loop control of open-water channels from the perspective of large-scale irrigation network management. Several feedback information structures are discussed and the key design tradeoffs identified
    Proceedings of the IEEE 02/2007; · 6.91 Impact Factor
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    ABSTRACT: Actuator saturation can have a significant impact on control system performance. In particular, when actuators saturate because of large initial condition mismatch at startup, or because of large disturbances, the controller can suffer from so-called integrator windup. This paper describes the application of recent anti-windup and bumpless transfer (AWBT) compensation techniques to the problem of open water channel control. This is nontrivial in light of the (marginally) unstable nature of uncontrolled open water channels, which for the purposes of controller design, can modelled as a concatenation of integrators, linked by saturation-prone gates used to regulate the flow of water. AWBT compensator design is considered within the context of both continuous- and discrete-time controllers and models. All simulation studies are carried out using an experimentally validated, high-fidelity model of the Haughton Main Channel in Queensland, Australia. The AWBT compensation schemes considered achieve excellent performance.
    Control Engineering Practice 01/2007; 15(2):261-272. · 1.67 Impact Factor
  • Source
    Yuping Li, M. Cantoni, E. Weyer
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    ABSTRACT: We consider the propagation of water-level errors in a controlled string of (identical) pools comprising an open-water irrigation channel. It is shown that water-level errors are amplified as they propagate upstream, whenever the feedback control scheme is decentralised and load-disturbance rejection is required in steady-state. Moreover, a design trade-off is identified between local performance, in terms of set-point regulation and load-disturbance rejection, and the error-propagation characteristics. The use of feed-forward/decoupling paths is considered in terms of managing this trade-off. However, the corresponding analysis suggests it is difficult to exploit the extra degree of freedom. Finally, we investigate a so-called distributed generalisation of the decentralised schemes. This leads to an optimal control based framework for dealing with the design trade-off.
    Decision and Control, 2005 and 2005 European Control Conference. CDC-ECC '05. 44th IEEE Conference on; 01/2006
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    ABSTRACT: In Australia, gravity fed irrigation systems are critical infrastructure essential to agricultural production and export. By supplementing these large scale civil engineering systems with an appropriate information infrastructure, sensors, actuators and a communication network it is feasible to use systems engineering ideas to improve the exploitation of the irrigation system. This paper reports how classical ideas from system identification and control can be used to automate irrigation systems to deliver a near on-demand water supply with vastly improved overall distribution efficiency.
    Annual Reviews in Control. 01/2005;
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    ABSTRACT: In this paper we apply anti-windup bumpless transfer (AWBT) techniques for marginally stable linear plants to the windup-prone control systems of an open-water channel. AWBT constructions are carried out both for the continuous time and for the discrete time case and are based on preliminary results on L/sub 2/ (respectively l/sub 2/) anti-windup design. The anti-windup properties of these compensation laws (already published in the literature) are recalled and their bumpless transfer properties (corresponding to recent research results) are also discussed. Although the controller and AWBT designs are carried out on simplified linear models of the open water channel, the simulation results are carried out on an experimentally validated high fidelity model of the Haughton Main Channel (Queensland, AU) and show excellent behavior of the AWBT compensation laws, both in continuous and in discrete time.
    Control Conference, 2004. 5th Asian; 08/2004
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    ABSTRACT: This paper describes the design of a multivariable H∞ loop-shaping controller for water level regulation on the Haughton Main Chan-nel, Queensland Australia. A one-degree-of-freedom controller structure is applied to three successive pools. Analysis of robust performance is pre-sented in terms of the structured singular value. Closed-loop performance is also evaluated through simulations with high fidelity models of the channel. The controller shows better performance than decentralized PI control, and attains similar performance to a multivariable LQ controller. The H∞ loop-shaping controller is, however, much easier to tune than an LQ controller. This becomes important when the number of pools to be controlled is increased. As such, it is an appealing design paradigm when high performance control of an irrigation channel is required.
    01/2004;
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    Yuping Li, Michael Cantoni
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    ABSTRACT: In the design of an automatic controller to achieve water-level set-point regulation and off-take load-disturbance rejection for an open water channel, a key concern is an inherent trade-off between local performance and the way water-level errors propagate due to control action. Here a structured optimal controller synthesis problem is formulated to systematically manage this trade-off, using H ∞ loop-shaping ideas. The loop-shaping weights can be scalably designed and the imposed structure ensures the controller only involves local information exchange. Importantly, the distributed control structure we consider confines water-level error propagation to upstream pools, with corresponding benefits in terms of water distribution efficiency. Moreover, it coincides with the interconnection structure of a channel, and so the corresponding optimal synthesis problem has a convex characterisation; detailed state-space formulae are provided. Field test data are presented to illustrate overall performance.