8,114 research outputs found
Disturbance Observer-based Robust Control and Its Applications: 35th Anniversary Overview
Disturbance Observer has been one of the most widely used robust control
tools since it was proposed in 1983. This paper introduces the origins of
Disturbance Observer and presents a survey of the major results on Disturbance
Observer-based robust control in the last thirty-five years. Furthermore, it
explains the analysis and synthesis techniques of Disturbance Observer-based
robust control for linear and nonlinear systems by using a unified framework.
In the last section, this paper presents concluding remarks on Disturbance
Observer-based robust control and its engineering applications.Comment: 12 pages, 4 figure
Engineering Time-Reversal Invariant Topological Insulators With Ultra-Cold Atoms
Topological insulators are a broad class of unconventional materials that are
insulating in the interior but conduct along the edges. This edge transport is
topologically protected and dissipationless. Until recently, all existing
topological insulators, known as quantum Hall states, violated time-reversal
symmetry. However, the discovery of the quantum spin Hall effect demonstrated
the existence of novel topological states not rooted in time-reversal
violations. Here, we lay out an experiment to realize time-reversal topological
insulators in ultra-cold atomic gases subjected to synthetic gauge fields in
the near-field of an atom-chip. In particular, we introduce a feasible scheme
to engineer sharp boundaries where the "edge states" are localized. Besides,
this multi-band system has a large parameter space exhibiting a variety of
quantum phase transitions between topological and normal insulating phases. Due
to their unprecedented controllability, cold-atom systems are ideally suited to
realize topological states of matter and drive the development of topological
quantum computing.Comment: 11 pages, 6 figure
Definition, Characteristics and Determining Parameters of Antennas in Terms of Synthesizing the Interrogation Zone in RFID Systems
The radio frequency identification (RFID) systems are gaining in popularity in automated processes of object identification in various socioeconomic areas. However, despite the existing belief, there is no universal RFID system on the commercial market that could be used in all user applications. All components of a developed solution should be carefully selected or designed according to the specification of objects being recognized and characteristics of their environment. In order to determine parameters of propagation or inductively coupled system, especially when it is dedicated to uncommon applications, a multiaspect analysis has to be taken into consideration. Due to complexity, the problem is reduced to analytical or experimental determination of RFID system operation range and a “trial and error” method is mostly used in the industry practice. In order to cope with the barriers existing in the RFID technology, the authors give the review of latest achievements in this field. They focus on the definition, comprehensive characteristics and determination of the antenna parameters. They also pay attention to the 3D interrogation zone (IZ) that is the main parameter in which multitude technical aspects of the RFID systems are gathered simultaneously, as regards the theoretical synthesis as well as market needs
Digital Phase Locked-Loop With Wide Tuning Range And Dynamic Phase Shift
For decades, Phase Lock Loop (PLL) has been widely used in numerous systems, such as telecommunications and digital design, where it plays significant role in improving overall system timing. Moving forward, with the latest revolution towards System-on-chip technology (SOC), the need of PLL in the form of Integrated Circuits has been growing tremendously. Core of this research is to design a PLL with wide tuning range and dynamic phase shift feature, which is implemented in the Integrated Circuits level. In line with fierce competition
and fast-paced semiconductor industry, PLL design with above features are definitely most sought after, as it will tremendously reduce turn-around time, cost and effort for a project. Wide tuning range is achieved by introducing new Voltage Control Oscillator architecture,
which will be able to provide wide tuning range without using very high KVCO. The new architecture proposed in this project is in differential input structure and consists of MOSFETs and capacitors; thus the area of implementation is small.Besides, extra feature which is proposed in this PLL is Dynamic Phase Shift feature.
Dynamically tunable phase shift is important since the accuracy of the phase could be adjusted without having to reprogram the PLL, thus saving a lot of time. Dynamic Phase Shift feature is a new idea, which its design is implemented by using UP/DOWN counters, OR and AND gates. The complete design includes synchronous system design work such as state machine, diagram and truth table for system simplification. This proposed design achieved all specifications with wide-tuning range of 600MHz to
1300MHz is achieved with control voltage swing of 0.9V to 1.5V. Besides, the maximum static phase error measured in the simulation is 66ps, which is smaller than 200ps
specification. Highest Period Jitter is 181ps while Cycle-to-Cycle Jitter is 55ps. Both types of jitter are within specification; lower than 300ps. Dynamic Phase Shift also successfully implemented where the UP/DN signal as the control to indicate either the phase is to be shifted up or down
Process and Temperature Compensated Wideband Injection Locked Frequency Dividers and their Application to Low-Power 2.4-GHz Frequency Synthesizers
There has been a dramatic increase in wireless awareness among the user community in the past five years. The 2.4-GHz Industrial, Scientific and Medical (ISM) band is being used for a diverse range of applications due to the following reasons. It is the only unlicensed band approved worldwide and it offers more bandwidth and supports higher data rates compared to the 915-MHz ISM band. The power consumption of devices utilizing the 2.4-GHz band is much lower compared to the 5.2-GHz ISM band. Protocols like Bluetooth and Zigbee that utilize the 2.4-GHz ISM band are becoming extremely popular.
Bluetooth is an economic wireless solution for short range connectivity between PC, cell phones, PDAs, Laptops etc. The Zigbee protocol is a wireless technology that was developed as an open global standard to address the unique needs of low-cost, lowpower, wireless sensor networks. Wireless sensor networks are becoming ubiquitous, especially after the recent terrorist activities. Sensors are employed in strategic locations for real-time environmental monitoring, where they collect and transmit data frequently to a nearby terminal. The devices operating in this band are usually compact and battery powered. To enhance battery life and avoid the cumbersome task of battery replacement, the devices used should consume extremely low power. Also, to meet the growing demands cost and sized has to be kept low which mandates fully monolithic implementation using low cost process.
CMOS process is extremely attractive for such applications because of its low cost and the possibility to integrate baseband and high frequency circuits on the same chip. A fully integrated solution is attractive for low power consumption as it avoids the need for power hungry drivers for driving off-chip components. The transceiver is often the most power hungry block in a wireless communication system. The frequency divider (prescaler) and the voltage controlled oscillator in the transmitter’s frequency synthesizer are among the major sources of power consumption. There have been a number of publications in the past few decades on low-power high-performance VCOs. Therefore this work focuses on prescalers.
A class of analog frequency dividers called as Injection-Locked Frequency Dividers (ILFD) was introduced in the recent past as low power frequency division. ILFDs can consume an order of magnitude lower power when compared to conventional flip-flop based dividers. However the range of operation frequency also knows as the locking range is limited. ILFDs can be classified as LC based and Ring based. Though LC based are insensitive to process and temperature variation, they cannot be used for the 2.4-GHz ISM band because of the large size of on-chip inductors at these frequencies. This causes a lot of valuable chip area to be wasted. Ring based ILFDs are compact and provide a low power solution but are extremely sensitive to process and temperature variations. Process and temperature variation can cause ring based ILFD to loose lock in the desired operating band.
The goal of this work is to make the ring based ILFDs useful for practical applications. Techniques to extend the locking range of the ILFDs are discussed. A novel and simple compensation technique is devised to compensate the ILFD and keep the locking range tight with process and temperature variations. The proposed ILFD is used in a 2.4-GHz frequency synthesizer that is optimized for fractional-N synthesis. Measurement results supporting the theory are provided
System Level Synthesis
This article surveys the System Level Synthesis framework, which presents a
novel perspective on constrained robust and optimal controller synthesis for
linear systems. We show how SLS shifts the controller synthesis task from the
design of a controller to the design of the entire closed loop system, and
highlight the benefits of this approach in terms of scalability and
transparency. We emphasize two particular applications of SLS, namely
large-scale distributed optimal control and robust control. In the case of
distributed control, we show how SLS allows for localized controllers to be
computed, extending robust and optimal control methods to large-scale systems
under practical and realistic assumptions. In the case of robust control, we
show how SLS allows for novel design methodologies that, for the first time,
quantify the degradation in performance of a robust controller due to model
uncertainty -- such transparency is key in allowing robust control methods to
interact, in a principled way, with modern techniques from machine learning and
statistical inference. Throughout, we emphasize practical and efficient
computational solutions, and demonstrate our methods on easy to understand case
studies.Comment: To appear in Annual Reviews in Contro
Reconfigurable Reflectarrays and Array Lenses for Dynamic Antenna Beam Control: A Review
Advances in reflectarrays and array lenses with electronic beam-forming
capabilities are enabling a host of new possibilities for these
high-performance, low-cost antenna architectures. This paper reviews enabling
technologies and topologies of reconfigurable reflectarray and array lens
designs, and surveys a range of experimental implementations and achievements
that have been made in this area in recent years. The paper describes the
fundamental design approaches employed in realizing reconfigurable designs, and
explores advanced capabilities of these nascent architectures, such as
multi-band operation, polarization manipulation, frequency agility, and
amplification. Finally, the paper concludes by discussing future challenges and
possibilities for these antennas.Comment: 16 pages, 12 figure
Automatic characterization and generation of music loops and instrument samples for electronic music production
Repurposing audio material to create new music - also known as sampling - was a foundation of electronic music and is a fundamental component of this practice. Currently, large-scale databases of audio offer vast collections of audio material for users to work with. The navigation on these databases is heavily focused on hierarchical tree directories. Consequently, sound retrieval is tiresome and often identified as an undesired interruption in the creative process.
We address two fundamental methods for navigating sounds: characterization and generation. Characterizing loops and one-shots in terms of instruments or instrumentation allows for organizing unstructured collections and a faster retrieval for music-making. The generation of loops and one-shot sounds enables the creation of new sounds not present in an audio collection through interpolation or modification of the existing material. To achieve this, we employ deep-learning-based data-driven methodologies for classification and generation.Repurposing audio material to create new music - also known as sampling - was a foundation of electronic music and is a fundamental component of this practice. Currently, large-scale databases of audio offer vast collections of audio material for users to work with. The navigation on these databases is heavily focused on hierarchical tree directories. Consequently, sound retrieval is tiresome and often identified as an undesired interruption in the creative process.
We address two fundamental methods for navigating sounds: characterization and generation. Characterizing loops and one-shots in terms of instruments or instrumentation allows for organizing unstructured collections and a faster retrieval for music-making. The generation of loops and one-shot sounds enables the creation of new sounds not present in an audio collection through interpolation or modification of the existing material. To achieve this, we employ deep-learning-based data-driven methodologies for classification and generation
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