2,269 research outputs found
Event-based State Estimation: An Emulation-based Approach
An event-based state estimation approach for reducing communication in a
networked control system is proposed. Multiple distributed sensor agents
observe a dynamic process and sporadically transmit their measurements to
estimator agents over a shared bus network. Local event-triggering protocols
ensure that data is transmitted only when necessary to meet a desired
estimation accuracy. The event-based design is shown to emulate the performance
of a centralised state observer design up to guaranteed bounds, but with
reduced communication. The stability results for state estimation are extended
to the distributed control system that results when the local estimates are
used for feedback control. Results from numerical simulations and hardware
experiments illustrate the effectiveness of the proposed approach in reducing
network communication.Comment: 21 pages, 8 figures, this article is based on the technical report
arXiv:1511.05223 and is accepted for publication in IET Control Theory &
Application
Observer techniques for estimating the state-of-charge and state-of-health of VRLABs for hybrid electric vehicles
The paper describes the application of observer-based state-estimation techniques for the real-time prediction of state-of-charge (SoC) and state-of-health (SoH) of lead-acid cells. Specifically, an approach based on the well-known Kalman filter, is employed, to estimate SoC, and the subsequent use of the EKF to accommodate model non-linearities to predict battery SoH. The underlying dynamic behaviour of each cell is based on a generic Randles' equivalent circuit comprising of two-capacitors (bulk and surface) and three resistors, (terminal, transfer and self-discharging). The presented techniques are shown to correct for offset, drift and long-term state divergence-an unfortunate feature of employing stand-alone models and more traditional coulomb-counting techniques. Measurements using real-time road data are used to compare the performance of conventional integration-based methods for estimating SoC, with those predicted from the presented state estimation schemes. Results show that the proposed methodologies are superior with SoC being estimated to be within 1% of measured. Moreover, by accounting for the nonlinearities present within the dynamic cell model, the application of an EKF is shown to provide verifiable indications of SoH of the cell pack
Reset control for DC-DC converters: an experimental application
© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Power converters in grid connected systems are required to have fast response to ensure the stability of the system. The standard PI controllers used in most power converters are capable of fast response but with significant overshoot. In this paper a hybrid control technique for power converter using a reset PI + CI controller is proposed. The PI + CI controller can overcome the limitation of its linear counterpart (PI) and ensure a fast flat response for power converter. The design, stability and cost of feedback analysis for a DC-DC boost converter employing a PI + CI controller is explored in this work. The simulation and experimental results which confirm the fast, flat response will be presented and discussed.Peer ReviewedPostprint (published version
CPU-less robotics: distributed control of biomorphs
Traditional robotics revolves around the microprocessor. All well-known demonstrations of sensory guided motor control, such as jugglers and mobile robots, require at least one CPU. Recently, the availability of fast CPUs have made real-time sensory-motor control possible, however, problems with high power consumption and lack of autonomy still remain. In fact, the best examples of real-time robotics are usually tethered or require large batteries. We present a new paradigm for robotics control that uses no explicit CPU. We use computational sensors that are directly interfaced with adaptive actuation units. The units perform motor control and have learning capabilities. This architecture distributes computation over the entire body of the robot, in every sensor and actuator. Clearly, this is similar to biological sensory- motor systems. Some researchers have tried to model the latter in software, again using CPUs. We demonstrate this idea in with an adaptive locomotion controller chip. The locomotory controller for walking, running, swimming and flying animals is based on a Central Pattern Generator (CPG). CPGs are modeled as systems of coupled non-linear oscillators that control muscles responsible for movement. Here we describe an adaptive CPG model, implemented in a custom VLSI chip, which is used to control an under-actuated and asymmetric robotic leg
Nonlinear observers for predicting state-of-charge and state-of-health of lead-acid batteries for hybrid-electric vehicles
AbstractâThis paper describes the application of state-estimation
techniques for the real-time prediction of the state-of-charge
(SoC) and state-of-health (SoH) of lead-acid cells. Specifically,
approaches based on the well-known Kalman Filter (KF) and
Extended Kalman Filter (EKF), are presented, using a generic
cell model, to provide correction for offset, drift, and long-term
state divergenceâan unfortunate feature of more traditional
coulomb-counting techniques. The underlying dynamic behavior
of each cell is modeled using two capacitors (bulk and surface) and
three resistors (terminal, surface, and end), from which the SoC
is determined from the voltage present on the bulk capacitor. Although
the structure of the model has been previously reported for
describing the characteristics of lithium-ion cells, here it is shown
to also provide an alternative to commonly employed models of
lead-acid cells when used in conjunction with a KF to estimate
SoC and an EKF to predict state-of-health (SoH). Measurements
using real-time road data are used to compare the performance
of conventional integration-based methods for estimating SoC
with those predicted from the presented state estimation schemes.
Results show that the proposed methodologies are superior to
more traditional techniques, with accuracy in determining the
SoC within 2% being demonstrated. Moreover, by accounting
for the nonlinearities present within the dynamic cell model, the
application of an EKF is shown to provide verifiable indications of
SoH of the cell pack
A feasibility study for reset control of an industrial batch reactor
Includes abstract.Includes bibliographical references (leaves 128-133).A feasibility study for the application of reset control to the temperature control loop of a pressurized exothermic batch leach reactor in the hydrometallurgical Precious Group Metals (PGM) industry is carried out. Keywords: Reset control; Clegg integrator; initial states; industrial batch reactor; temperature control; exothermic reactions; multiple reactions; dissolve; leach; hydrometallurgy; platinum; Precious Group Metals (PGMs)
Fast Beam Current Change Monitor for the LHC
StriktnĂ nĂĄroky na systĂ©my ochrany a zabezpeÄenĂ LHC vyĆŸadujĂ vylepĆĄenĂ© metody detekce rychlĂœch ztrĂĄt ÄĂĄsticovĂ©ho svazku. RychlĂœ proudovĂœ transformĂĄtor (FBCT) je mÄĆicĂ pĆĂstroj poskytujĂcĂ informaci o intenzitÄ shlukĆŻ urychlovanĂœch ÄĂĄstic. Tato diplomovĂĄ prĂĄce popisuje vĂœvoj novĂ©ho systĂ©mu ochrany LHC zaloĆŸenĂ©ho na mÄĆenĂ signĂĄlu FBCT. Tento systĂ©m, monitor rychlĂœch proudovĂœch zmÄn ÄĂĄsticovĂ©ho svazku (FBCCM), mÄĆĂ signĂĄl FBCT v ĂșzkĂ©m frekvenÄnĂm pĂĄsmu a poÄĂtĂĄ Äasovou derivaci okamĆŸitĂ© amplitudy tohoto signĂĄlu. Tato derivace je pĆĂmo ĂșmÄrnĂĄ ztrĂĄtĂĄm ÄĂĄsticovĂ©ho svazku. Pokud ztrĂĄty svazku pĆekroÄĂ urÄitou ĂșroveĆ, FBCCM pĆikĂĄĆŸe kontrolnĂm systĂ©mĆŻm zniÄit svazek kvĆŻli bezpeÄnosti LHC. Ochrana LHC bude zabezpeÄena ÄtyĆmi FBCCM, kterĂ© budou instalovĂĄny do LHC v Äervenci 2014. Bylo zkonstruovĂĄno a testovĂĄno ĆĄest FBCCM. Jejich mÄĆenĂ© charakteristiky vyhovujĂ stanovenĂœm poĆŸadavkĆŻm. FBCCM bylo vyzkouĆĄeno laboratornĂ simulacĂ reĂĄlnĂ©ho prostĆenĂ LHC.Stringent demands on the LHC safety and protection systems require improved methods of detecting fast beam losses. The Fast Beam Current Transformer (FBCT) is a measurement instrument, providing information about bunch-to-bunch intensity of the accelerated beam. This thesis describes the development of a new protection system based on the FBCT signal measurements. This system, the Fast Beam Current Change Monitor (FBCCM), measures the FBCT signal in a narrow frequency band and computes time derivation of the beam signal magnitude. This derivation is proportional to the beam losses. When the losses exceed a certain level, the FBCCM requests a beam dump in order to protect the LHC. The LHC protection will be ensured by four FBCCMs which will be installed into the LHC in July 2014. Six FBCCMs have been already constructed and their characteristics were measured with satisfactory results. The FBCCMs were tested by a laboratory simulation of the real LHC environment.
Fast and Reliable Primary Frequency Reserves From Refrigerators with Decentralized Stochastic Control
Due to increasing shares of renewable energy sources, more frequency reserves
are required to maintain power system stability. In this paper, we present a
decentralized control scheme that allows a large aggregation of refrigerators
to provide Primary Frequency Control (PFC) reserves to the grid based on local
frequency measurements and without communication.
The control is based on stochastic switching of refrigerators depending on
the frequency deviation. We develop methods to account for typical lockout
constraints of compressors and increased power consumption during the startup
phase. In addition, we propose a procedure to dynamically reset the thermostat
temperature limits in order to provide reliable PFC reserves, as well as a
corrective temperature feedback loop to build robustness to biased frequency
deviations. Furthermore, we introduce an additional randomization layer in the
controller to account for thermostat resolution limitations, and finally, we
modify the control design to account for refrigerator door openings.
Extensive simulations with actual frequency signal data and with different
aggregation sizes, load characteristics, and control parameters, demonstrate
that the proposed controller outperforms a relevant state-of-the-art
controller.Comment: 44 pages, 17 figures, 9 Tables, submitted to IEEE Transactions on
Power System
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