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This paper studies an optimal formation control problem of general integrator chain multi-agent systems with strongly convex local cost functions. The control goal is to design appropriate controllers for the agents such that they reach a desired formation shape and the global cost function is minimized. To achieve the goal, a modular control scheme with two modules is proposed. First, in Module I, an optimal formation signal generator is designed, whose outputs asymptotically converge to the minimizer of the global cost function. Second, in Module II, by employing the outputs into the feedback loop as the agents reference trajectories, some linear tracking controllers are designed for the agents to track the references asymptotically. With both modules, the proposed control scheme realizes the optimal formation control goal asymptotically. Moreover, the proposed control scheme is also applied to solving an optimal formation control problem of multiple mobile robots, where the robots total relative weighted squared moving distance requires minimization. Both simulations and experiments validate the effectiveness of the proposed control scheme.

This paper investigates the distributed fixed-time attitude coordinated control problem for multiple spacecraft subject to actuator saturation under the directed topology. First, a distributed fixed-time observer is presented for each follower spacecraft to estimate the leader spacecraft’s states. Compared with the commonly used fixed-time observer, the settling time of the proposed fixed-time observer can be easily adjusted by some free design parameters. Next, a distributed fixed-time control scheme is derived by using the estimates of the leader spacecraft's states and the adding a power integrator technique. When considering actuator saturation, an auxiliary system is utilized to compensate the saturation. Further, a rigorous theoretical proof is provided to show that the practical fixed-time stability of the closed-loop system is ensured. Finally, simulation results illustrate the benefits and effectiveness of the developed control scheme.

Unbalanced grid voltages, appearing at stator terminals of a doubly fed induction generator (DFIG) based wind energy conversion system (WECS) deteriorate its performance, by instigating unwanted oscillations and distortions in output grid power and rotor currents, respectively, as well as by introducing unbalanced currents in the stator and the grid. This paper aims to address these challenges using a coordinated control strategy based on an improved reduced order generalized integrator (IROGI) for positive and negative sequence estimation (PNSE). The IROGIPNSE further enhances the control performance, by eliminating the effects of any DC component or unbalance in sensed voltages, on grid synchronization. The coordinated control strategy uses hysteresis scheme for current control. The hysteresis based current control requires fewer rotational transformations, and eliminates the need for PI/PIR regulators and notch filters for inner current control loops. This renders the control, computationally efficient. Moreover, the presented system is equipped to exhibit wind power levelling functionality, through a battery energy storage (BES). An approach, employing the region-specific wind speed frequency distribution graph, is utilized to constitute the power levelling operation modes. The effectiveness of the control scheme is demonstrated through test results on a prototype developed in the laboratory.

This brief presents a low-noise, low-power bio-signal acquisition analog front-end (Bio-AFE). It mainly includes a capacitively coupled chopper-stabilized instrumentation amplifier (CCIA), a programmable gain amplifier (PGA), a low-pass filter (LPF), and a successive approximation analog to digital converter (SAR ADC). A chopper-capacitor-chopper integrator based DC servo loop (CIB-DSL) to suppress the electrode DC offset (EDO) with low noise, low process-voltage–temperature (PVT) sensitivity is proposed. Besides, a low power GM-C filter of which the input linear range is extended via inverse hyperbolic tangent pre-distortion circuit is proposed to filter out the spikes, ripples, and high frequency noise in front end. A capacitive feedback PGA is employed to realize a tunable gain of the front end. And a low power SAR ADC is applied to quantify the acquired bio-signal. The proposed analog front end has been fabricated in a 0.18m CMOS process with an area of 0.57mm, consuming 3.5 A from a 1V supply voltage. It achieves an integral noise from 0.5 to 100Hz of 1.16Vrms, ±90mV EDO cancellation range, an ADC effective number of 9.06 bit, and the -59.6 dB total harmonic distortion (THD) of total AFE.

This contribution presents charge-based capacitive self-sensing with a continuous full state observer for a parametrically driven resonant electrostatic 1D MEMS mirror considering precise and seamless estimation. Based on current integrators, series capacitances or a capacitance network the direct charge self-sensing principles are investigated and compared considering leakage currents, precision and a minimum implementation effort. In comparison to the other charge sensing methods, the proposed methods directly measure the charge changes while the drive voltage is switched on. Since resonant MEMS mirrors are driven by a rectangular signal, the direct self-sensing implies a lack of data when the drive voltage is switched off. A nonlinear observer is also proposed to estimate the full mirror state continuously based on an identified MEMS mirror model. The capacitive charge self-sensing methods achieve overall a high sensing precision of less than 0.14 % RMSE and the observer estimation error of the full state is below 1 % peak-to-peak error regardless of the availability of the charge self-sensing measurements, demonstrates accurate continuous full state estimation. [2021-0130]

To design noise-shaping successive approximation register (NS-SAR) analog-to-digital converters (ADCs) with high resolution and good power efficiency, two key bottlenecks need to be addressed. One is to realize a high-order loop filter with low circuit overhead, and the other is to mitigate the thermal noise. This article presents an NS-SAR ADC that synergistically addresses both challenges. To achieve high-order efficiency, it proposes an innovative error feedback-cascaded integrator feedforward (EF-CIFF) structure that realizes third-order noise shaping using only a single amplifier. It combines the merits of both structures, showing improved robustness, and is free of dc offset concern. On reducing the kT/C noise, this work features a sampling kT/C noise cancellation (SNC) technique that reuses the native hardware of the EF-CIFF structure. An open-loop self-quenching floating-inverter dynamic amplifier (FIDA) is used to support all amplification with low noise and power. Prototyped in 65-nm CMOS, this work achieves 84.8-dB signal-to-noise-distortion ratio (SNDR) with 625-kHz bandwidth (BW) (OSR = 8) and 119 $\mu \text{W}$ , leading to 182-dB Schreier Figure of Merit (FoM). It uses only 0.8-pF input capacitance, which is $5\times $ smaller than prior NS-SAR ADCs with similar oversampling ratio (OSR) and SNDR.

This paper presents a practical approach to developing a speed limiter using a disturbance observer (DOB) and a speed observer. A nominal plant model is designed assuming that the vehicle is a lumped mass. The plant uncertainty and external disturbance are lumped into a disturbance term and compensated for by the DOB. With the contribution of the DOB, the proposed controller can reduce overshoot and minimize steady-state error without feedforward and integrator control. In addition, the speed observer is also designed to reduce the overshoot due to noise such as offset, lag, and communication delay between the display speed and wheel speed, because the proposed controller operates according to the display speed. The proposed controller was validated by vehicle experiments performed on a C-segment hybrid electric vehicle (HEV) and achieved superior performance compared to conventional controllers.

The charge-generating sensors are widely used in many applications in consumer, automotive and medical electronics. They generate a charge proportional to the applied input quantity: pressure, temperature, acceleration, strain, light, etc. Usually, charge amplifiers are used to register such signals. The charge amplifier is an integrator that integrates the input current over time. In continuous-time signal processing, a parallel resistor is used to dissipate the energy stored on the integration capacitor, and such self-zeroed integrator circuits are known as lossy integrators. To achieve low-frequency operation, when a capacitor is in the picofarad range, a very high-ohmic resistor, in the range of gigaohms, must be used. Such a high-ohmic resistor increases the output offset voltage to an unacceptable level. To overcome the output offset problems, a composite charge amplifier has been recently introduced. This paper presents an innovative lossy integrator readout circuit which contains only one opamp in the feedback. The circuit can be easily adapted to the needed gain and cut-off frequency. Its operation is validated by experimental results. The sufficiently low high-pass cut-off frequency allows the circuit to be used for biosignal amplification. Heart and respiration rates can be easily recorded with piezoelectric sensors attached to the wrist or lung wall. The presented circuit can benefit many applications where charge-to-voltage conversion is needed.

This article presents multi-touch readout IC embedding finger-resistance extraction (FRE) on a capacitive touch screen panel (TSP). The proposed FRE mode is aimed to have the ability to tell users apart while sensing touch input by utilizing a unique finger’s resistance due to different bio-electrical properties. The resonance-driven FRE technique and a clamped zoom-in integrator are exploited to obtain a wide dynamic range (DR). A switched-capacitor current-controlled oscillator-based 14-bit analog-to-digital converter (ADC) was also designed, which has the benefits of low noise, compact size, and high flexibility of its resolution. The prototype chip fabricated in 0.18- $\mu \text{m}$ CMOS achieved the measured signal-to-noise ratio (SNR) of 37.5 dB and DR of 50.7 dB in touch sensing and FRE modes, respectively, in a real-6.7-in capacitive TSP. By applying support vector machine learning to the FRE data, five different user-fingers were successfully classified with 97.7% accuracy after 500 learning cycles and thus demonstrating the feasibility of reliable user-differentiation on multi-user collaborative touch interfaces.

This article implements a new control method for a microgrid configuration comprising wind energy generation system, a solar PV array, a battery, local loads, and the utility grid, which provides a seamless transition of power during on-grid to off-grid operations and vice versa. This microgrid uses synchronous reluctance generator (SynRG) operated by a position (mechanical) sensor-less field-oriented control, for electric power generation from a variable speed wind turbine. The output of the solar PV array is connected to the dc-link of the microgrid through a dc–dc boost converter, whose output voltage is regulated at the desired value by the battery bank. For smooth synchronization and fast dynamic response, a fourth-order generalized integrator-based frequency-locked-loop with pre-filter (C-FGI-FLL) is implemented in this work. The use of C-FGI-FLL enhances the filtering capabilities of FGI-FLL under weak grid conditions, without affecting the computational burden. The C-FGI-FLL generates filtered input and its quadrature component, and these are used for the extraction of positive sequence components of the grid voltages. For faster dynamic response during load variations, C-FGI filters are used in each phase so that fundamental peaks of load currents are extracted accurately without any delay. The accurate and quick performance of this filter makes the system dynamics fast without deteriorating the performance. Simulation and experimental validations of this microgrid have been carried out both for dynamic and steady-state conditions.

This paper investigates the finite-time attitude stabilization of spacecraft under multiple uncertainties. Besides inertia uncertainties, external disturbances, and actuator faults, the measurement uncertainties are particularly considered. When including the measurement uncertainties, the spacecraft attitude control system becomes a mismatching system, which brings a great challenge to the control design. To resolve this problem, a novel robust finite-time attitude control approach is proposed by using a dual-disturbance-observer-based structure. First, two finite-time disturbance observers are developed to estimate the mismatched and matched lumped disturbances in the spacecraft attitude kinematics and dynamics, respectively. Then, the robust finite-time attitude controller is synthesized by incorporating the two finite-time disturbance observers into the adding a power integrator technique. It is strictly proved that the proposed robust finite-time attitude controller can ensure the actual attitude and angular velocity stabilize to the small neighborhoods around the origin in finite time even subject to multiple uncertainties. Benefiting from the feedforward disturbance compensation, the proposed controller is not only robust against inertia uncertainties, external disturbances, and actuator faults, but also insensitive to measurement uncertainties. Lastly, the effectiveness and advantages of the proposed control approach are validated through simulations and comparisons.

This article deals with a robust control strategy for a distributed generation system (DGS), which operates in both islanded and grid-connected modes. Generally, in the low-voltage islanded mode of DGS, the point of common coupling (PCC) voltages are unbalanced due to the unbalanced load connection. Therefore, in an islanded mode of DGS, the load-side converter is controlled using the improved proportional resonant controller to maintain the PCC voltages quality within the IEEE-1547 standard. Moreover, the DGS is capable to synchronize to the grid without any transient current. During the change of modes of DGS, large transients occur in the battery current due to the switching of battery control. This problem is resolved by the presented bidirectional dc–dc converter control strategy and robust inner-loop quadrature second-order generalized integrator-based phase-locked loop. The effectiveness of this DGS control strategy is verified by the corresponding MATLAB/Simulink platform under load unbalance, solar irradiance changes, and during the mode of switching. Moreover, the simulation results are validated using the test results and show the robustness of the control strategy during abnormal grid voltage condition.

This chapter provides some answers to the question regarding the case when the desired value for the regulated output – that is, the signal that is fed in the integrator of the proportional‐integral‐derivative (PID) – is nonzero. It explores possible solutions to design PID‐passivity‐based control. After presenting the theoretical results pertaining to the issues, the chapter illustrates their application to the control of power converters, high‐voltage direct‐current (HVDC) power systems, wind energy systems, and permanent‐magnet synchronous motors. For its correct operation, HVDC systems must satisfy a large set of different regulation objectives that are, typically, associated with to the multiple time‐scale behavior of the system. One way to deal with this issue, that prevails in practice, is the use of hierarchical architectures. These are nested control loops, at different time scales, each one providing references for an inner controller. The chapter provides conditions for shifted passivity of port‐Hamiltonian systems.

B-dot sensor, as an important device, is extensively employed to measure the current flowing in the magnetically insulated transmission line (MITL). To shield the output signal of the B-dot sensor from electron flow and high electrical field in the MITL anode-cathode (A-K) gap and also avoid the electrical breakdown in the A-K gap, the sensor is often covered with the metallic film and located in a conductor cavity penetrating the MITL electrode hole simultaneously. The frequency response properties of such kind of sensor are investigated. The experiment results indicate that the upper limited response frequencies of the sensors with and without the attached $5-\mu $ m-thick Ni-Chrome foil are 50 MHz and 148 MHz, respectively. Moreover, as a result of penetration of magnetic flux into the cavity’s wall and the wire loops wound to form the sensor, the low-frequency components of the B-dot sensor output signal are amplified, consequently the falling edge of the waveform given by the B-dot probe will be distorted. We have proposed a method to make a first-order correction for such effect by using a passive resistor-capacitor integrator instead of the numerical process suggested previously. The integrator combines the behaviors of integration and compensation of the B-dot sensor output. The actual measured current waveform can be directly obtained by multiplying the output signal of the integrator by the sensitivity of the B-dot monitor. The B-dot sensors and this post-processing method have been successfully used on a pulsed power accelerator.

In renewable system control engineering, Maximum Power Point Tracking (MPPT) techniques are considered as one of the key steps in photovoltaic (PV) system development. Indeed, some MPPT techniques ...

In this brief, a recurrent network was derived for a neural integrator (NI) described by an ordinary differential equation (ODE) that can be solved with fewer computational resources. Subsequently, based on the reduced ODE model, a hardware-oriented recurrent network model was proposed for a NI consisting of asynchronous cellular automaton (CA) neurons. The proposed model, reduced ODE model, and the previously proposed NI model were implemented on a field-programmable gate array. Analysis results suggest that the proposed model consumes fewer hardware resources and lower power than those of the reduced ODE model and the previously proposed NI model.

Power semiconductor devices have maximum junction temperature limits, but it is not straightforward to sense or infer temperature inside sealed devices in running converters. One method is to observe electrical behavior that is known to be temperature dependent. For example, in some gallium nitride (GaN) power semiconductor devices, the maximum slope of the device current at turn- on has been shown to reduce as the junction temperature increases. This article demonstrates the first noncontact overtemperature protection circuit for GaN power devices that exploits this effect and overcomes the complication that this inverse proportionality is affected by load current. A variant of a previously reported magnetic field “Infinity Sensor,” named after its figure-of-eight topology and high bandwidth (>200 MHz), measures di/dt . Using the sensor signal as the only input, a detection circuit finds peak di/dt , and a high-speed integrator derives instantaneous load current. The reference voltage for the decision-making part of the circuit is automatically adjusted as a function of load current, in order to counteract the dependence of di/dt on load current. Experimental results on a 400 V, 2 kW buck converter show the protection circuit successfully activating within ±5 °C of a preprogrammed junction temperature setting, independently of load current, for settings of 100, 120, and 140 °C.

Conventional back electromotive force (EMF) estimation based active flux concept for sensorless control has various limitations due to pure integrator problems and performance deterioration at low speeds. The fundamental back EMF component extraction with a conventional low pass filter, is difficult due to the presence of lower order harmonics, dc offset, saturation, etc., and causes significant phase delay in the estimated position and speed. This article deals with a sensorless speed and position estimation technique for a surface mounted permanent magnet synchronous motor (SPMSM) based electric vehicle (EV) drive using a sliding mode observer (SMO) with a dual second order generalized integrator frequency locked loop (DSOGI-FLL). A novel method of utilizing the DSOGI-FLL, along with feedforward term is shown to achieve better harmonic elimination of estimated back EMF components and faster dynamic speed estimation. A delay compensated predictive current controller-based PMSM EV drive with the presented estimation technique is used for improved dynamic response. This system is simulated using Simulink and its efficacy is experimentally validated using dSPACE 1202. Test results show that the DSOGI-FLL-based SMO has better performance compared to the conventional technique.

Analog optical computing has been an innovation and research interest in last several years, thanks to the ultra-high speed (potential for real-time processing), ultra-low power consumption and capability of parallel processing. Although great efforts have been made recently, no on-chip optical spatial-domain integrator has been experimentally demonstrated, to the best of our knowledge. Based on Fourier optics and metasurface, we design and fabricate an on-chip optical integrator using silicon-on-insulator (SOI) platform. The proposed integrator is able to integrate the electric field in spatial domain. As a proof-of-concept demonstration, a representative optical signal is well integrated to the desired distribution. Compared with theoretical expectation, the similarity coefficients of the simulated and experimental results are 83 and 78%, respectively. The proposed scheme has potential of performing more complex and ultra-high-speed computing for artificial intelligence.

This paper demonstrates a hardware encryption algorithm that can be integrated directly with sensors on the same chip. In contrast to using power-hungry microprocessors and software implementations, the encryption algorithm was based on a Lorenz chaotic system and was implemented as time scaling chaotic shift keying (TS-CSK). The coupled differential equations of TS-CSK were implemented using low power integrators, multiplexers, switches, and passive components. Both a single-ended and differential system was developed. The single-ended based system showed no oscillation, while the differential based system demonstrated oscillation. Experimental measurements of the differential system with an integrated temperature sensor demonstrated the ability to encrypt and decrypt the transmitted signal. The differential encryption/decryption system was implemented in 180 nm technology and operated with a 1.8 V power supply and 1.5 mW of power.

Grid synchronization techniques play a significant role in integrating renewable energy sources to the electric power grid. In this context, estimating the phase and frequency of the grid voltage signal is an interesting problem. Out of various techniques available in the literature, linear Kalman filter (LKF) is one of the most popular one. In this article, we propose an alternative implementation of the LKF for grid synchronization application. The proposed implementation uses a linear parametric model of the grid voltage signal including dc offset. It does not involve any quadrature signal generation, rather it works by estimating the phase angle. This helps to estimate the unknown grid frequency directly from the phase angle. This clearly differentiates the proposed alternative implementation with respect to the existing implementations. Performance improvement by the proposed technique is verified extensively through comparative numerical simulation and experimental studies. Comparative results demonstrate the suitability of the proposed technique with respect to other state-of-the-art techniques namely second-order generalized integrator phase-locked loop and enhanced phase-locked loop.

This article presents a low-power audio continuous-time delta-sigma modulator (CTDSM) that employs a chopped negative-R and a tri-level finite impulse-response (FIR) DAC. The noise of the first opamp is mitigated by using a negative-R at the virtual ground of the first integrator, and the negative-R is then chopped to remove the intrinsic ${1/f}$ noise of the negative-R. The highly linear feedback DAC is realized with a 6-tap tri-level FIR-DAC whose inter-symbol interference (ISI) is kept less than −120 dB. The CTDSM fabricated in 65-nm CMOS technology occupies an active area of 0.28 mm2. It achieves 99.4-dB SNDR, 101-dB SNR, 102.8-dB dynamic range (DR), and 110.2-dB SFDR in a 24-kHz bandwidth, while consuming only $134~\mu \text{W}$ . This corresponds to a state-of-the-art figure-of-merit (FoM) of 185.3 dB.

The present study is concerned with overcoming the resultant image degradation due to the integration of the optoelectronics instruments (OEIDs). Accordingly, the characteristics of the image, due to optoelectronic integration, are handled and improved. The image features include the transmission mechanism and the concentration of electrons. The device performance is improved through the optimal design of the basic parameters. Furthermore, the efficient design of structure parameters will minimize the reabsorption process. Optimization of the integrator structure is realized. MATLAB environment is used for devising this instrument. The optimal number of integrator base and wave number characterizing the scale of near-infrared (NIR) image nonuniformity are estimated to be 13 and 0.206 respectively. The output of this instrument is also conducted through closed-form expressions of the underlined instrument. The achieved results show a remarkable accuracy for handling the deformations raised during the integration process. In addition, the results show that the carrier concentration changes the behavior of the output of the NIR image.

The need for technology and technology has led to a sharp acceleration of experimental design and research work to study in an ultrahigh vacuum environment, both surface and bulk properties of solids. The accumulation of basic knowledge about surfaces, especially semiconductor materials, makes it possible to develop modern semiconductor devices in electronics and microelectronics. In this work, a time-of-flight mass spectrometric setup is proposed, the use of which makes it possible to obtain objective information about such processes as adsorption and desorption on the surface of semiconductors. Mass spectrometry is a physical method for analyzing the composition of complex mixtures of substances and identifying individual substances in them by their mass spectra. The mass spectrum is obtained as a result of ionization of substances, separation of ions according to their mass numbers (the ratio of the mass of an ion to its charge) and measurement of the intensity of ion currents for all ions. The mass spectrum allows conclusions to be drawn about the molecular weight of the sample, its composition and structure. The study of adsorption processes makes it possible to qualitatively change the conditions on the surface of semiconductors, which in turn change the energy spectrum of electrons in the near-surface region and leads to the production of both efficient photocathodes with negative electron affinity and an MIS structure with specified parameters. The novelty of this setup lies in the fact that, along with the existing standard units, blocks and devices (a rectangular pulse generator that controls the power supply of an electron gun, an ion source, an electron multiplier for registering ions by masses, a pulse broadband amplifier, a gate signal delay unit, valve, integrator and indicator) are used in order to increase the speed, accuracy and reliability of measurements. Recommended additionally a waiting square-wave generator, two pulse expanders and a comparison unit, while the input of the waiting square-wave generator is connected to the output of the master pulse generator, and its two outputs are connected to the inputs of pulse expanders, the outputs of which are connected to the inputs of the comparator connected with their output to the stroboscopic signal delay unit, they can qualitatively improve the operation of the installation.

One of the grand challenges of this century is modeling and simulating a whole cell. Extreme regulation of an extensive quantity of model and simulation data during whole-cell modeling and simulation renders it a computationally expensive research problem in systems biology. In this article, we present a high-performance whole-cell simulation exploiting modular cell biology principles. We prepare the simulation by dividing the unicellular bacterium, Escherichia coli (E. coli), into subcells utilizing the spatially localized densely connected protein clusters/modules. We set up a Brownian dynamics-based parallel whole-cell simulation framework by utilizing the Hamiltonian mechanics-based equations of motion. Though the velocity Verlet integration algorithm possesses the capability of solving the equations of motion, it lacks the ability to capture and deal with particle-collision scenarios. Hence, we propose an algorithm for detecting and resolving both elastic and inelastic collisions and subsequently modify the velocity Verlet integrator by incorporating our algorithm into it. Also, we address the boundary conditions to arrest the molecules' motion outside the subcell. For efficiency, we define one hashing-based data structure called the cellular dictionary to store all of the subcell-related information. A benchmark analysis of our CUDA C/C++ simulation code when tested on E. coli using the CPU-GPU cluster indicates that the computational time requirement decreases with the increase in the number of computing cores and becomes stable at around 128 cores. Additional testing on higher organisms such as rats and humans informs us that our proposed work can be extended to any organism and is scalable for high-end CPU-GPU clusters.

This paper describes systematic measurements of the main parameters of the DIMEX-Si silicon microstrip detector prototype, designed to study fast processes in a beam of synchrotron radiation (SR). The dynamic range, spatial resolution and temporal parameters of the detector are estimated. The parameters of the prototype silicon detector are compared with the DIMEX-G gas version. The maximum flux which can be measured by the silicon detector is 40 times higher than that of the gas detector. The spatial resolution of the silicon detector is 130 microns and that of the gas detector is 250 microns. The estimated time resolution of the silicon detector is 15 ns, while for a gas detector this value is about 50 ns. All the characteristics of DIMEX-Si are measured with a cycle time of 25 ns. The results of the first tests of a full-scale silicon detector for diffraction studies, operating in the integrating mode at a speed of up to 2 Mframes/s, are also given. The sensor contains 1024 strips 30 mm long with a step of 50 microns; 512 of these strips are connected to readout electronics based on APC128 ASIC. Each chip contains 128 channels, which consist of a low-noise integrator with 32 analog memory cells. The possibility of signal visualization from single photons and electrons from 109Cd and 90Sr sources is shown.

The ability to keep track of one’s location in space is a critical behavior for animals navigating to and from a salient location, and its computational basis is now beginning to be unraveled. Here, we tracked flies in a ring-shaped channel as they executed bouts of search triggered by optogenetic activation of sugar receptors. Unlike experiments in open field arenas, which produce highly tortuous search trajectories, our geometrically constrained paradigm enabled us to monitor flies’ decisions to move toward or away from the fictive food. Our results suggest that flies use path integration to remember the location of a food site even after it has disappeared, and that flies can remember the location of a former food site even after walking around the arena one or more times. To determine the behavioral algorithms underlying Drosophila search, we developed multiple state transition models and found that flies likely accomplish path integration by combining odometry and compass navigation to keep track of their position relative to the fictive food. Our results indicate that whereas flies re-zero their path integrator at food when only one feeding site is present, they adjust their path integrator to a central location between sites when experiencing food at two or more locations. Together, this work provides a simple experimental paradigm and theoretical framework to advance investigations of the neural basis of path integration.

We introduce here our new approach to modeling particle cloud evolution off surface of small bodies (asteroids and comets), following the evolution of ejected particles requires dealing with various time and spatial scales, in an efficient, accurate and modular way. In order to improve computational efficiency and accuracy of such calculations, we created an N-body modeling package as an extension to the increasingly popular orbital dynamics N-body integrator Rebound. Our code is currently a stand-alone variant of the Rebound code and is aimed at advancing a comprehensive understanding of individual particle trajectories, external forcing, and interactions, at the scale which is otherwise overlooked by other modeling approaches. The package we developed -- Rebound Ejecta Dynamics (RED) -- is a Python-based implementation with no additional dependencies. It incorporates several major mechanisms that affect the evolution of particles in low-gravity environments and enables a more straightforward simulation of combined effects. We include variable size and velocity distributions, solar radiation pressure, ellipsoidal gravitational potential, binary or triple asteroid systems, and particle-particle interactions. In this paper, we present a sample of the RED package capabilities. These are applied to a small asteroid binary system (characterized following the Didymos/Dimorphos system, which is the target for NASA's Double Asteroid Redirection Test mission), Comment: 13 pages, 11 figures, 4 tables, 2 appendices. Published (advance access) on 2/15/2021, see https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/stab408/6136266?redirectedFrom=fulltext

This work introduces a second-order voltage-controlled oscillator (VCO)-based continuous-time delta–sigma modulator (CTDSM) that incorporates a distributed-input VCO as the second-stage integrator and quantizer. The distributed-input VCO topology virtually eliminates the VCO’s voltage-to-frequency (V-F) parasitic pole. One of the key ideas of this article is to demonstrate the use of a capacitive- $\pi $ network in the modulator’s loop filter to break the constraint between the size of the modulator’s inner capacitive digital-to-analog converter (DAC) and the factor by which the front-end Gm-C integrator is impedance scaled. This, in turn, helps to significantly reduce both analog and digital powers. The prototype chip has been fabricated in a 40-nm CMOS process. Despite not using any DAC calibration or explicit dynamic element matching (DEM) circuits, the worst case spurious-free dynamic range (SFDR) is −82 dBc across the signal bandwidth. The fabricated CTDSM achieves a 71.8-dB signal-to-noise-and-distortion ratio (SNDR) and a 74.5-dB dynamic range (DR) in a 10-MHz bandwidth at 655 MS/s, yielding an SNDR-based Walden figure of merit (FoM) of 45.6 fJ/step, an SNDR-based Schreier FoM of 167.2 dB, and a DR-based Schreier FoM of 169.9 dB.

This article proposes a voltage-to-frequency converter (VFC) design using unipolar metal-oxide thin film transistor (TFT) technology. The proposed VFC has an integrator and Schmitt trigger based structure. This structure has the advantages of constant power consumption, full-swing output, and low circuit complexity compared to the early designs. To verify the proposed design, SmartSpice simulation based on a Rensselaer Polytechnic Institute (RPI) model whose parameters are turned to fix the measured characteristics of our indium tin oxide- (ITO-) stabilized ZnO TFTs is carried out. The ITO-stabilized ZnO TFT has a single-gate staggered structure. Its typical field-effect mobility, threshold voltage, on/off current ratio, and subthreshold-slope are 14.5 cm2/Vs, 0.5 V, $1.2{\mathrm {\times }} 10^{8}$ , and 77 mV/decade, respectively. Simulation results show that the proposed VFC has maximum linearity error less than 1.8%, tuning sensitivity about 1 kHz/V, and power consumption less than $130~{\mu }\text{W}$ even under device variations. These performances are competitive compared to the state-of-the-arts. When configured to an analog-to-digital converter (ADC), 6 bit resolution and 14 S/s sampling rate can be realized. These results indicate that the VFC can find potential applications in flexible large-area low-voltage sensor interfaces for quasi-static signals.

This paper presents a charge-balanced readout circuit for MEMS capacitive accelerometers. The focus of this work is a design with a low-noise and low area consumption while ensuring the essential linearity and electromagnetic compatibility (EMC) for automotive applications. The readout circuit is composed of a charge-balanced single-ended input C/V stage followed by a second order sigma-delta modulator. The C/V stage uses a Gm stage combined with an integrator to reduce its noise contribution. The measurement results of the readout circuit show a noise floor of 62 $\mu g/{\sqrt {\mathrm{ Hz}}}$ and a temperature dependent offset smaller than ±0.6 mg after compensation. The measured dynamic range of the complete interface, including readout circuit and sensor, is 95.5 dB. The measured EMC is below 2 mg. The accelerometer readout circuit has been designed in a 130nm technology. Its power and area consumption is 1.4 mW and 0.26mm2.

This article aims to develop a unique configuration of a solar-powered water pumping system (SPWPS), which ensures an uninterruptable water supply along with the earning possibility for the consumer. This water pumping system utilizing the switched reluctance motor drive, needs no current sensor on the motor side to run the system. The concept of integrating the grid to the SPWPS as an electrical energy storage device, provides assistance against the fluctuations in power, minimum electricity cost and earns from excess of photovoltaic power. An efficient control logic for grid-side voltage source converter is developed in this article. It has multiple intends like to regulate the desired dc-link voltage, to maintain the power quality and to improve the dynamic responses. This controller incorporates the second- and third-order generalized integrator-based filter for fundamental component extraction of grid voltage and has the benefits of both the filters. Moreover, the new control logic for dual output boost converter as a maximum power point tracking converter is also proposed in this article. It helps to simultaneously maximize the solar power as well as to nullify the voltage asymmetry across both dc-link split capacitors of a mid-point converter under all operating modes. The applicability of the developed arrangement with designed control logic is verified by experimental results.

To improve the efficiency of Logistics Service Supply Chain (LSSC) order allocation and to maximize customer satisfaction, this paper built a LSSC under cloud environment, analyzed the logistics services integrator order allocation process, designed an algorithm mixed K-Means and Qos matching, analyzed the complexity of the algorithm, and finally designed the simulation experiments to test the recall ratio and precision of the mixing algorithm. The results show that the proposed algorithm can effectively avoid service regression and maximize customer needs.

In this article, a novel single-layer decoupled multiple-order generalized integral-based control algorithm is used for a single-stage solar energy grid integrator (SEGI) with maximum power extraction. The single-layer decoupled structure is used to extract the fundamental component of load current. Moreover, the online grid frequency estimation is carried out for an accurate band-pass filtering. The single-layer architecture of the control for the three-phase load current estimation, reduces the control complexity, and improves the response time. Moreover, the single-stage system is operated with the maximum power point tracking based on the residual incremental conductance algorithm. Hence, the cost of a new conversion stage and additional control are saved. This system is operated under three operating modes. In “normal-mode,” it feeds power to the load and the grid. Wherein the “sharing mode,” SEGI and grid supply the load power. During the night, SEGI functions as an active filter, which is termed as “filter-mode.” The steady-state and dynamic performances of SEGI during each operating mode and transition between the modes due to irradiation variation as well as load fluctuation are verified experimentally on a developed prototype. Moreover, test results under dynamic load variations such as nonlinear and unbalanced load conditions are presented to validate the theoretical claims.

This paper mainly studies a bumpless transfer controller which can be applied to a certain gas turbine. Due to the requirements of low exhaust emission and high combustion efficiency, the gas supply system of the gas turbine is composed of duty fuel, master fuel, and secondary fuel, which inevitably lead to the switching problem in the control system. In order to solve this problem, we have built a three-branch natural gas supply system in the Amesim software and established a gas turbine model in the Simulink software according to its mechanism. In addition, the gas turbine model and the natural gas system model are jointly simulated through the interface. Finally, in accordance with the traditional PID gas turbine controller, an active disturbance rejection controller (ADRC) is designed, which is combined with a bumpless transfer controller including differentiator and integrator to suppress the interference caused by fuel switching. The effectiveness and superiority of this strategy are verified by the complete joint simulations.

This letter presents a low-power continuous-time delta–sigma modulator (CTDSM) that operates at a 0.6-V supply. The loop filter of the CTDSM is realized with inverter-based integrators and negative-R compensation on each integrator’s virtual ground. A body-biasing technique is used for inverters as well as for negative-Rs to ensure robustness against process, voltage, and temperature (PVT) variations. A prototype CTDSM is fabricated in a 28-nm CMOS process and achieves 83-dB SNDR, 84-dB SNR, and 86.5-dB DR in a 40-kHz bandwidth while consuming only 33.6 $\mu \text{W}$ from a 0.6-V supply. This corresponds to the state-of-the-art Schreier FoM of 177.3 dB.

This paper presents a high-resolution analog front-end (AFE) circuit operating in the 25 kHz signal bandwidth. The AFE consists of a capacitively-coupled chopper instrumentation amplifier (CCIA) and a third-order delta-sigma modulator (DSM). Signal distortion often occurs at the junction of CCIA and DSM, so the resistor-based discrete-time DSM (RB DT–DSM) is proposed to solve this problem. Both conventional DT–DSM and the proposed RB DT–DSM are designed and compared through simulations and chip measurements. When a conventional DT–DSM is used, a switched-capacitor integrator with a large capacitor and switch are connected to the CCIA output node, so large switching noise, significant charge injection, and a long settling time occur at the CCIA output, resulting in harmonic distortions. Therefore, CCIA requires more power consumption to reduce the settling time for conventional DT–DSM architectures. On the other hand, when the proposed RB DT–DSM is used, only a resistor and a small switch are connected to the CCIA output. Due to this novel interface technique, the switching noise is very small at the CCIA output, and the settling of the CCIA becomes fast. As a result, it is possible to effectively eliminate harmonic distortions while reducing the power requirement of the CCIA. Both the conventional and proposed AFE circuits were manufactured by a 0.18- $\mu \text{m}$ complementary metal-oxide-semiconductor (CMOS) process. The conventional AFE shows a peak SNR of 101.1 dB and a peak SNDR of 91.2 dB. The proposed AFE with RB DT–DSM shows a peak SNR of 101.3 dB and a peak SNDR of 100.5 dB, which verifies the significant reduction in harmonic distortions.

A joint multiple-input multiple-output (MIMO) processing framework is proposed to exploit spatial diversity and moving cues for the enhancement of target detection in a shallow ocean environment. Orthogonal signals are transmitted to illuminate different aspects of a target and beamforming operation is carried out over the received data for estimating target bearing. The target range is achieved by a replica correlation integrator where the beamformer outputs are matched with transmitted signals. After meanshift clustering algorithm is carried out over the bearing-range spectrums to generate the clutter centers, the potential trajectories of targets can be tracked by an improved Bernoulli filter with inputs of these centers. The at-sea experimental results have shown the effectiveness of the joint processing framework in MIMO detection of moving targets.

We demonstrate a photonic RF integrator based on an integrated soliton crystal micro-comb source. By multicasting and progressively delaying the input RF signal using a transversal structure, the input RF signal is integrated discretely. Up to 81 wavelengths are provided by the microcomb source, which enable a large time-bandwidth product of 81. Our approach also features a high degree of reconfigurability. By simply adjusting the value of dispersion (i.e., the length of dispersive fibre), the integration time window and resolution can be reconfigured to accommodate a diverse range of applications. We employed 13 km of standard single-mode fibre to achieve a large integration time window of ~6.8 ns, a time resolution as fast as ~84 ps, with a broad bandwidth of 11.9 GHz. In addition, we perform signal integration of a diverse range of input RF signals including Gaussian pulses with varying time widths, dual pulses with varying time intervals and a square waveform. The experimental results show good agreement with theory. These results verify our microcomb-based integrator as a competitive approach for RF signal integration with high performance and potentially lower cost and footprint.

In this article, a new control methodology is implemented for a microgrid consisting of wind-battery and the grid, which operates both under grid-connected mode and standalone mode. A synchronous reluctance generator (SynRG) with a new mechanical sensorless field-oriented control is used in the wind energy generation system (WEGS). The major issues present in the sensorless control of SynRG, due to the use of conventional integrator or low-pass filter during the flux estimation, are addressed in this article by implementing a fourth-order flux estimator. To compensate for the intermittent nature of the power generated from the WEGS, and to improve the reliability of the system pertaining to power availability, energy storage is included in the system. Controlled operation of the battery is ensured by using a bidirectional dc–dc converter, to enhance the longevity of the battery. Voltage source converters (VSCs) connected in a back-to-back configuration with a common dc-link is selected here so that a complete decoupling is achieved between the grid and WEGS. Grid-side VSC (GSC) is controlled, so that power quality at the point of common coupling is improved. The positive sequence components of grid voltages are extracted using observers to implement GSC control to avoid the adverse effects of unbalance and harmonic content in grid voltages. Design, modeling, and simulation of the system are done in MATLAB/SIMULINK platform, and a prototype developed in the laboratory is used for real-time validation.

This paper illustrates a novel design of voltage-mode integrator using the active element, namely voltage difference transconductance amplifier (VDTA). The proposed circuit only requires one VDTA element and a single capacitor. This provides more beneficial for the fabrication of ICs in VLSI design. The designed circuit works with ±0.9 V supply voltage, uses a bias current of order 150 μA. And also, the transconductance (gm) is electronically tunable with the bias current. The proposed circuit is designed in a gpdk 180 nm CMOS process using a Cadence Virtuoso tool and also has the power dissipation of order 270 µW. The simulation results are functionally verified through experiment with the commercially available ICs LM13700. The proposed VDTA based integrator is highly useful in the dual slope/integrating type analogue to digital converters for higher resolutions.

In this study, we developed an X-ray detector module (XDM) that includes two readout electronic units and a 64-channel data acquisition system for X-ray imaging systems. The readout electronic unit comprises eight X-ray sensor arrays (two CdWO4 scintillators and four Si-PIN photodiodes per detector array), 32 charge integrators, 32 sample-and-holds (S/H), 4 shift registers, and a buffer. The data acquisition system comprises line drivers and receivers, a multiplexer, an analog-to-digital converter, and a 32-kB static random-access memory. All the control signals for module operation are implemented in a field-programmable gate array. The module operates with a single 24 V DC supply and transfers each channel’s data to the host computer through an Ethernet port. We fabricated a 64-channel electronic module and evaluated its performance in terms of the relative offset and linearity. By connecting 14 XDMs, air-cargo container images were successfully acquired through X-ray irradiation at an energy of 6-MeV.

To understand the fundamental parameters of Alvand tokamak, A Rogowski coil with an active integrator was designed and constructed. Considering the characteristics of the Alvand tokamak, the structural and electrical parameters affecting the sensor function, were designed. Calibration was performed directly in the presence of plasma. The sensor has a high resistance against interference of external magnetic fields. Plasma current was measured in various experiments. Based on the plasma current profile and loop voltage signal, the time evolution of plasma discharge was investigated and plasma behavior was analyzed. Alvand tokamak discharge was divided into several regions that represents different physical phenomena in the plasma. During the plasma discharge time, plasma had significant changes and its characteristic was not uniform. To understand the plasma behavior in each of the phases, the Rogowski sensor should have sufficient time resolution. The Rogowski sensor with a frequency up to 15 kHz was appropriate for this purpose.

This article presents an automated procedure for developing wide bandgap semiconductor device models capable of capturing high-frequency effects in applications relevant to next generation power electronics. A derivative-free global optimization algorithm is used to autonomously model both the static and dynamic behavior of a power semiconductor device. This procedure is demonstrated with a specific model, but the procedure is model-agnostic and not exclusive to this implementation. The modeling procedure creates a compact and modular power electronic device model accounting for both frequency-dependence of device inter-electrode capacitances and characterization uncertainty of device parasitic package inductances. The procedure targets prediction of specific signal features in the transient device behavior. Digital twin development and validation are performed under disparate switching conditions to demonstrate the overall improvement in model predictive power. The proposed modeling approach serves to reduce manual model development time, while improving time-domain prediction under switching conditions of interest to application engineers and systems integrators. This is particularly important in the case of wide bandgap semiconductors, which pose challenges for conventional device models due to their fast switching dynamics. The effectiveness of the presented method is demonstrated by automatically generating a device model for a 1.2-kV SiC mosfet and comparing predicted switching behavior with empirical double pulse test behavior.

A delta-sigma modulator (DSM) is proposed for the direct connection to micro-electro-mechanical systems (MEMS) microphone. To reduce power, both the DAC reference voltage (VREF) and the DSM supply voltage (VDD) are reduced to 700 mV by limiting the maximum linear acoustic input range to 110 dB SPL (sound pressure level). For the low VDD operation, the switched capacitor (SC) integrators of DSM employ CMOS inverters as amplifiers. A unity-gain buffer compensates the pole error of the SC integrator; it reduces chip area by replacing the auto-zero capacitor of conventional inverter-based SC integrator. Compared to the conventional integrator, the integrator of this brief reduces the pole error from 0.3% to 0.06%, reduces the chip area and the power by 32.4% and 24.8%, respectively. The 3rd order DSM in a 65 nm CMOS process was measured to have Walden-figure of merit (FoMw) 89.3fJ/step, dynamic range (DR) 90.1 dB, signal-to-noise ratio (SNR) 87.2 dB, signal-to-noise and distortion ratio (SNDR) 86.4 dB, and power 122 uW at 10 MHz clock frequency (Fs).

This article addresses a controller for a full converter of variable-speed wind generators composed of permanent magnet synchronous generators. Conventionally, several proportional–integral (PI) controllers and a phase-locked loop (PLL) are used in the full converter for voltage-oriented control. The use of cascaded control loops with PI controllers degrades the control performance due to the windup of the integrators and complicates the tuning task. In this article, we propose a new full converter control scheme based on predictive control and a single P-controller in the $\alpha \beta$ stationary frame to replace the integrators and the PLL. The proposed controller can reduce the parameter tuning effort, is free from integrator windup, and is robust to symmetrical and asymmetrical voltage dips. The effectiveness of the proposed method is verified through simulations.

An efficient control of a grid integrated microgrid with wind energy generating system (WEGS) and a battery storage, is implemented in this work. The quality of power injected to the utility is deteriorated with the level of unbalance and/or distortions present in the grid voltages. To compensate for the abnormalities, such as unbalance and distortions in the grid voltages, positive sequence components (PSCs) of grid voltages are extracted from their filtered $ \alpha \beta$ components. This work implements hybrid generalized integrator (HGI) filters for filtering the $ \alpha \beta$ components of grid voltages and also provides its 90 $\circ$ delayed signals, which are useful in generating PSCs. Phase and frequency of the grid currents are decided by the unit active templates derived from the PSCs of the grid voltages, therefore, high-quality grid currents are injected into the grid even for abnormal grid conditions. For faster dynamics during variations in load power, HGI filters are used for quick and accurate estimation of fundamental components of load currents. Intermittent power generation from WEGS is compensated for by integrating a battery bank into the system. Along with high-quality power injection, the grid side converter operates the microgrid in off-grid mode (during grid outages) and provides smooth grid integration once the grid reappears. A 3.7 kW speed sensorless synchronous reluctance generator is used in WEGS, which is controlled by the machine side converter. The control techniques are validated in MATLAB /Simulink platform, and experimental validation is done on a prototype developed in the laboratory.

A common feature of the traditional high-order sliding mode (HOSM) control method is that the matched uncertainty of HOSM dynamics is enlarged by taking the high-order derivatives on the pre-selected sliding variable directly, which could cause much burden to the controller design. This deficiency is removed in this paper via introducing some nonlinear terms in the mismatched channels. On this basis, a new arbitrary-order HOSM dynamics with lower-triangular nonlinearities will be obtained. Then, a novel finite-time HOSM control approach an be developed by the aid of the mathematical tool named as adding a power integrator (API). Under the proposed HOSM algorithm, the mismatched uncertainties existing in the new HOSM dynamics are not required to be sufficiently smooth, but are needed to comply with a few homogeneous growth conditions. Moreover, the common constant boundary for the matched uncertainty in the majority of the available HOSM methods can be extended to a time-varying one. The rigorous proof is given based on the Lyapunov theory to show the finite-time stability of the considered closed-loop system. At last, an example of the robotic tracking system is adopted to validate the effectiveness of the developed finite-time HOSM control method.

A high-precision digital interface circuit is achieved for a tunnel magneto-resistance sensor with a high sensitivity and high dynamic range. The analog front-end detection circuit adopts the structure of a current feedback instrumentation amplifier, and a chopper technology and ripple suppression loop are used to improve the performance. In the back-end digital conversion part, a fourth-order fully feedforward sigma-delta modulator is designed, and the chopper circuit is further applied to eliminate the low frequency noise and offset of the first-stage integrator. The measurement results show that with the input equivalent magnetic field signal amplitude of 100 mV centered at 31 Hz, the SFDR of the final digital output stream reaches 95 dB, and the overall power consumption is 30 mW.

The three-degree-of-freedom (3D) pendulum has been used as a benchmark in the field of nonlinear dynamics and control. Nonetheless, the attitude control of 3D pendulum is still an open problem presently since some issues remain not well addressed. In this paper, a robust adaptive finite-time attitude control method is proposed for the attitude tracking control of a 3D pendulum with external disturbance. First, a baseline finite-time attitude controller is designed based on the adding a power integrator technique. Then, a finite-time disturbance observer is designed to exactly estimate the unknown external disturbance. Finally, a robust adaptive finite-time attitude controller is constructed by integrating the baseline finite-time attitude controller with the finite-time disturbance observer. The proposed robust adaptive finite-time attitude controller can guarantee the global finite-time stability of the whole closed-loop system even in the presence of external disturbance owing to the feedforward dynamic compensation. Numerical simulations and hardware experiments are both performed to illustrate the effectiveness and superiority of the proposed control method.