Order Low Pass Research Articles

State-of-charge estimation for lithium-ion batteries based on modified unscented Kalman filter using improved parameter identification

The full and single hybrid pulse power characterization (HPPC) experiments are conducted on nickel cobalt manganese (NCM) and lithium iron phosphate (LFP) batteries to obtain the accurate relationship between state of charge (SOC) and open circuit voltage (OCV). The pseudo random number generated by the RAND function is used as the initial value of the parameter identification equation for the second-order equivalent circuit model (ECM), and the parameter identification of lithium-ion batteries is achieved through least squares fitting. The unscented Kalman filter (UKF) simulation model is modified by the first order low pass filtering (FOLPF) algorithm to improve the accuracy of SOC estimation of batteries. The results show that the goodness of fit between the real and estimated HPPC pulse voltage values at different SOC values is above 0.99 for both NCM and LFP batteries. Based on the parameter identification results, the maximum error of the HPPC voltage estimated by the second-order ECM is within 0.045 V under both full pulse and single pulse testing conditions while the maximum error of SOC estimation is within 0.025. The UKF model modified by the FOLPF algorithm provides a reference for the accurate SOC estimation of batteries.

Nature inspired algorithm based design of near ideal fractional order low pass Chebyshev filters and their realization using OTAs and CCII

Fractional order filters offer greater freedom of design and a precise control over stopband attenuation in electronic circuits and systems. This paper presents the design of a fractional order low pass Chebyshev filter (FOLCF) that achieves near-ideal response characteristics. The methodology introduced utilizes metaheuristic optimization methods, including particle swarm optimization, firefly algorithm, and grey wolf optimization. These techniques are employed to precisely adjust the filter coefficients for the orders (1+α), (2+α), and (3+α). The adjustment is carried out by comparing the desired behaviour of the FOLCF with generalized fractional order low pass transfer functions. Throughout these instances, the parameter α is varied within the range of (0, 1). The designed filters are then tested and compared on the basis of various factors. Simulation results demonstrate that the designed filters closely follow the behaviour of an ideal Chebyshev filter with maximum passband and stopband magnitude errors being −31.93 dB and −52.74 dB respectively for (1+α) order filters. These values for (2+α) and (3+α) order FOLCF have been observed to be −30.04 dB and −55.91 dB; −17.72 dB and −49.52 dB respectively. Furthermore, it has been observed that the proposed work outperforms existing state-of-the-art approaches in various aspects, including magnitude error, stopband attenuation, and cut-off frequency. The stability of the designed filters has been verified through stability analysis. Additionally, practical feasibility of the proposed FOLCF is demonstrated through SPICE simulations for α = [0.2,0.5,0.8] using second generation current conveyor (CCII) and operational transconductance amplifier (OTA) based topologies while approximating the constant phase element using fifth order continued fraction expansion. The SPICE implementations closely follow the behaviour of ideal filter with −48.67 dB and −62.8 dB as mean square errors for CCII and OTA circuits respectively, showcasing the proposed filters' superiority and practical applicability in advanced electronic design.

A current mode capacitance multiplier employing a single active element based on Arbel-Goldminz cells for low frequency applications

In this work, a capacitor multiplier based on a Multiple Output-Voltage Difference Transconductance Amplifier (MO-VDTA) is built by using Arbel-Goldminz cells with extensive performance analysis. Considering the large chip area occupation of capacitors, capacitor multipliers are one of the most required analog building blocks in most of low frequency applications. In this respect, the obtained capacitor multiplier is tested in a 2nd order low-pass filter by changing the cut-off frequency from 2 kHz to around 12.4 kHz. The multiplication factor (denoted as “k”) of the proposed architecture can be adjusted electronically from 120 to 750 for approximately two decades, while the structure contains only a single active element with a base capacitance. Additionally, the multiplication factor can be safely increased by using additional transconductance stages in the MO-VDTA active block. In the performance analysis, post-layout results are provided in conjunction with process corners, Monte-Carlo analyses and experimental verifications on the basis of commercial off-the-shelf elements such as AD844 and LM13700s.

An electronically tunable fractional order inductor employing VD-EXCCII

An electronically tunable Fractional Order Inductor (FOI) for both grounded as well as floating circuits is designed using a Voltage Differencing Extra-X Current Conveyor (VD-EXCCII), grounded MOS resistor, and grounded Fractional Order Capacitor (FOC) with four MOS switches. The grounded positive and negative fractional order functionality can be easily executed by using the gate voltage (VG) of an MOS transistor. Ideal as well as the non-ideal port characteristics of VD-EXCCII are also studied in the presence of the parasites available in the active block VD-EXCCII. The verification of the proposed FOI is first simulated through PSPICE in which the VD-EXCCII uses 0.18 μm TSMC CMOS parameter. In addition to traditional impedance verification of the proposed FOI, an application of the FOI is translated for the design of sixth order High-Pass Filter (HPF), sixth order Low-Pass Filter (LPF), and a voltage mode Multiple Input Single Output Universal Filter (MISO-UF) design. Moreover, the performance of the proposed negative FOI circuit is also demonstrated through a Fractional Inductance Cancellation Circuit (FICC).

Realization of fractional order lowpass filter using different approximation techniques

Many research groups are starting to pay serious attention to the problem of fractional-order circuits. In this paper, a new approach to designing fractional order low-pass filter (FOLPF) is presented. Finding a rational approximation of the fractional Laplace operator sα is a crucial step in the design of fractional order filters. A comparative study of the most widely used approximation techniques named continued fraction expansion (CFE) method and Biquadratic Approximation (RE) method is performed. Then the transfer function of the proposed FOLPF is calculated. Using operational amplifier, the proposed filter is synthesized. The proposed circuit is simulated using Texas instruments TINA software. The results obtained outperform the existing methods.

Alernative Designs of an Active RC Realization of the Fourth Order Lowpass Butterworth Filter

In this tutorial article, we present two alternative designs of an active RC realization of the fourth-order lowpass Butterworth filter, in order to reduce the element spreads below those of an existing design, which uses a single amplifier of gain 2. The first method is based on simple observation of the design graphs given there, while the second one is a cascade of two second-order realizations, each using a unity gain amplifier. It is shown that retaining the capacitor spread to unity in the first design, a small adjustment of the gain reduces the resistance spread to less than half of the value obtained earlier. It is also shown that in the cascade design, the resistance spread can be made unity, but only at the cost of capacitor spread of 6.834.

Design of a Fractional Order Low-pass Filter Using a Differential Voltage Current Conveyor

In this paper, an active implementation of a differential voltage current conveyor (DVCC) based on a low-pass filter operating in the fractional order domain is presented. The transfer function for a fractional order system is dependent on the rational approximation of sα. Different methods used for calculating the rational approximation, including Carlson, Elkhazalil, and curve fitting, are evaluated here. Finally, to validate the theoretical results, a fractional order Butterworth filter is simulated in the Pspice environment using the 0.5 micrometer CMOS technology with an R-C network-based fractional order capacitor. Additionally, using the Monte Carlo analysis, the impact of current and voltage faults on DVCC response is investigated. It has been inferred that realization with a wider bandwidth is possible.

A self-adjusting multi-objective control approach for quadrotors

The quadrotor represents a class of highly nonlinear dynamic systems and its controllability features are challenging. Hence, it serves as an ideal unmanned aerial vehicle platform to validate many artificial intelligence-based research investigations. Nonetheless, most of the offline tuning approaches devote efforts to find near optimal control gains to regulate individually the decoupled motion directions. This work adopts a multi-objective self-adjusting search mechanism to actuate the motions of a quadrotor via deciding the control gains of the interacting loops simultaneously. This algorithm employs a first order low pass filter transfer function as an accepting approach for the tunning mechanism. The proposed approach is compared with a Genetic Algorithm and another nonlinear Proportional-Integral-Derivative approach to highlight the usefulness of the proposed mechanism. It was founded that quadrotor follows the desired trajectory with a small tracking error of less than 2% in the X-Y plane and less than 1 % error tracking error in the altitude Z. Also, it is recorded that MONLTA can overcome the simulated wind disturbances of 0.1 N.m as a disturbance torque.

Design and Analysis of a Fifth Order Low Pass Gm-C Filter for Seizure Detection

Design and Analysis of a Fifth Order Low Pass Gm-C Filter for Seizure Detection

Resilient Cooperative Output Regulation for Nonlinear Multiagent Systems Under DoS Attacks

The resilient cooperative output regulation problem for a class of uncertain nonlinear multi-agent systems (MASs) under denial-of-service (DoS) attacks is addressed in this paper. This is the first attempt to investigate the cooperative output regulation problem for nonlinear MASs under DoS attacks, and a novel distributed control scheme consisting of a resilient distributed observer and a distributed adaptive controller is proposed. Specifically, a novel resilient distributed observer in the form of an upper triangular chain of first order low pass filters is designed to estimate the exosystem state based on a composite output observability condition. Then, a distributed adaptive controller is designed. It is shown that the resilient cooperative output regulation problem for the concerned class of uncertain nonlinear MASs can be solved by the proposed control scheme. A simulation example is finally provided to show the effectiveness of the proposed control scheme.

Design and analysis of novel DGS-loaded low-pass filter with wide stopband

Abstract This article deals with design and development of a novel 7th order low-pass filter with defected ground structures for S-band applications. The proposed LPF structure was comprised of dumbbell shaped interdigital defected ground structures and open stubs as series inductor and shunt capacitor in the pass band. In addition, an equivalent circuit model was derived and optimized to achieve a 3-dB cut off frequency about 4 GHz with a reflection coefficient of better than −20 dB. Moreover, proposed low-pass filter was manufactured on a Rogers RO4003C substrate with a dielectric constant of 3.38, the dissipation factor of 0.0027. The developed LPF has a very flat pass-band with a transmission coefficient less than −0.5 dB and the measured transmission coefficient better than −18 dB in the passband (DC-3.6 GHz). Meanwhile, the prototype has a 20 dB harmonic suppression level in the frequency range from 5.54 GHz up to 43.5 GHz. Furthermore, the measured peak to peak group delay variation was less than 170 ps in the passband. The proposed filter has a very compact size of 195.3 mm2.

A Control Bandwidth Optimized Active Damping Scheme for LC and LCL Filter-Based Converters

Control bandwidth and damping performance are two key specifications for high-order LC and LCL filter-based converters. The damping of high-order filter-based converters has been extensively studied. However, the control bandwidth issue was ignored. The quantitative relationship between the control gains and bandwidth is still unclear. Moreover, the delay compensator was designed independently without considering the interactions with the main controller. This paper proposes a control bandwidth-optimized active damping control strategy for the LC and LCL filter-based converters to overcome these shortcomings. With the proposed generalized controller, the close loop transfer function of the N <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> order filter-based converter can be simplified to an N <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> order low pass filter with an adjustable cutoff frequency. This greatly simplifies the control bandwidth optimization. To alleviate the negative influence of the computational delay on the control bandwidth, a novel delay compensator is proposed. To reach an overall optimized control performance, the particle swarm optimization (PSO) method is used to optimize the controller and delay compensator parameters simultaneously to realize both high control bandwidth and good damping performance. Experimental results verify the effectiveness of the proposed novel controller.

Design and Fabrication of a Device for Reducing Hand Tremor in Parkinson Patients during Eating.

In this paper, the method of designing a noninvasive device for eliminating hand tremors in Parkinson's patients is presented. The designed device measures the tremors of the patient's hand and implements the tremor control accordingly. Since Parkinson's disease reduces patients' abilities to perform daily activities, this device is designed as an electronic spoon. The inertial measurement units are used to measure hand tremors. The signals got from motion sensors are passed through Butterworth's second order low pass filters to attenuate signals amplitude at frequencies higher than the human hand's natural frequency. The signals are sent to a proposed Proportional Integral (PI) fuzzy controller as a set point signal, and appropriate control signals are applied to two actuators installed orthogonal. Besides motion sensors, a microcontroller is installed inside the spoon handle that implements a PI fuzzy controller and provides control signals for two high speed servo motors installed perpendicularly. As such, the spoon can minimize the tremor effect. In this system, no damper or mass is added to the hand, and the patients are not required to wear an orthosis. The contribution of this paper is twofold. First, we use sensor data fusion to increase measurement accuracy. In this paper, we use accelerometer and gyroscope sensors. Second, we proposed a robust PI fuzzy controller to compensate for the uncertainties and reduce the tremor. The test results show that the hand tremor of Parkinson's patients during eating is reduced up to 75% using this method.

On Certain Noise Filtering Techniques in Fixed Point Iteration-based Adaptive Control

In control applications the use of noise-burdened sensor signals cannot be evaded. Also, certain signals can be lost. This problem traditionally is tackled by the use of Kalman filters that provide some “optimal solution” to these problems based on reasonable assumptions that are not always well underpinned in the practice. These are assumptions are made with regard to the system model and the statistical distribution of the noise signals. The Fixed Point Iteration-based adaptive controller is applicable for various strongly nonlinear models. Because feeding back the order of time-derivative of the system’s variable that immediately can be varied by the control signal, its noise sensitivity can be considerable. In this paper the operation of an unscented Kalman filter-based technique is compared with that of a simple moving window with affine signal approximation, and the use of a third order low pass filter in the control of a modified van der Pol oscillator. In this model a quadratic drag term is added to the original model to describe the motion of the system in turbulent fluid environment. According to the numerical simulations it can be stated that the simpler methods can replace the more complicated Kalman filter.

DynH 2 O: Aufbau zur metrologischen Charakterisierung der dynamischen Eigenschaften von Hygrometern

Abstract A novel flow switching setup for the dynamic generation and metrological detection of fast, isolated H2O concentration changes is presented and characterized. Based on this flow setup, very accurate, static H2O concentrations as well as highly dynamic H2O step changes of several 1000 ppmv (µmol/mol) can be generated and repeated. First experiments show that temporal water vapor concentration gradients of up to 10000 ppmv/s can be generated and measured. Based on this setup, a dynamic hygrometer characterization method was developed and demonstrated using a polymer-based hygrometer as device under test (DUT). The polymer hygrometer (with about 180 ppmv/s) proved to be more than 15 times slower than the optical reference hygrometer (with 3000 ppmv/s) and could be modeled and described well with a first order lowpass. To estimate the dynamics of the spatial and temporal H2O-profile, a fast, traversable, local sampling probe was developed and used in combination with a fast, extractive laser hygrometer (called SEALDH-II). The modeling of the H2O distribution in the dynamically operated flow channel enables the calculation of the dynamic concentration at the position of the DUT based on the data of the spatially averaging open-path laser reference hygrometer. In the future, this calculation will be used to determine a transfer function between the optical, open path reference hygrometer and the position of the DUT in order to extract the ideal step response of the DUT from the measured data of the flow channel.

Simulation Based Analysis of Low-Voltage-Tunable Biquad Filter Using Operational Transconductance Amplifiers

ABSTRACT A CMOS realisation of a voltage tunable biquad filter using only MOSFET-based operational transconductance amplifier (OTA) and capacitors has been designed using silicon-based CMOS technology. It operates at a low supply voltage of 0.25 V at a 500 MHz frequency. The filter is theoretically analysed and then simulated using commercially available Cadence Virtuoso tools at 0.18 μm CMOS technology parameters. The proposed design is used to implement second-order low pass, highpass, bandpass, and bandreject filters with the same circuit simply by tuning the input voltage. The bandwidth and cut-off frequency also can be changed by changing the capacitor values.

DVCC Based (2 + α) Order Low Pass Bessel Filter Using Optimization Techniques

This paper proposes the design and analysis of (2 + α) order low pass Bessel filter using different optimization techniques. The coefficients of the proposed filter are obtained by minimizing the error between transfer functions of (2 + α) order low pass filter and third-order Bessel approximation using simulated annealing (SA), interior search algorithm (ISA), and nonlinear least square (NLS) optimization techniques. The best optimization technique based on the error in gain, cut-off frequency, roll-off, passband, stopband, and phase is chosen for designing the proposed filter. The stability analysis of the proposed filter has also been done in W-plane. The simulated responses of the best optimized proposed filter are attained using the FOMCON toolbox of MATLAB and SPICE. The circuit realization of 2.5 order low pass Bessel filter is done using two DVCCs (differential voltage current conveyors), one generalized impedance converter (GIC) based inductor, and one fractional capacitor. The proposed filter is implemented for the cut-off frequency of 10 kHz using a wideband fractional capacitor. Monte Carlo and noise analyses are also performed for the proposed filter. The MATLAB and SPICE results are shown in good agreement.

First order lowpass and highpass filter using pole model of operational amplifier

A novel first order lowpass (LP) and Highpass (HP) filter using VDTA and operational amplifier is presented. It is a new kind of filter structure as it uses pole model of OA and VDTA. The OA pole model as a design parameter has been successfully utilized for realization of filters resulting high performance filters. The proposed circuit uses minimum number of components. The filter offers electronic tunability of the pole frequency which is highly required in IC technology. The sensitivities of the circuit are low. The workability of the proposed filter is verified using PSPICE simulation.

Parameters uncertainty analysis of posture control of a four-wheel-legged robot with series slow active suspension system

This paper focuses on the posture control performance on uneven terrain for a wheel-legged robot (WLR). Firstly, a novel four-wheel-legged robot (FWLR) with series slow active suspension system (SSASS) is proposed. Secondly, the parameters uncertainty of posture control is studied, and an 11 DOF dynamic model and the corresponding system state equation are presented. Thirdly, to suppress the chattering problem and enhance the robustness of traditional sliding mode controller (TSMC), the second order low-pass filter (SOLPF), equivalent speed control, saturation function, terrain estimation model and the actuator model are introduced into the control system, and an improved sliding mode controller (ISMC) is proposed. Finally, both the co-simulation and experiment on uneven terrain are carried out, the results show that even if the system parameters have 30% variation, the robot posture angle can be improved effectively. That is, the proposed robot and ISMC control strategy have good posture control performance with low parameters sensitivity on uneven terrain. Overall, this paper attempts to provide an effective way for the application of WLR on uneven terrain.

Sensitivity optimization method for 4th order CBQ structure LP filter

This paper describes the design and optimization method for a 4th order low-pass filter designed as a cascade of biquarts and approximated by Butterworth. Schoeffler sensitivity, multiparameter sensitivity measurement, and Monte Carlo analysis were used for sensitivity measurement, filter tuning, and optimization confirmation. The constraints on the filter characteristics due to the Butterworth approximation are also presented, together with the constraints on optimization to obtain a narrow range of values for the filter elements. Three different types of optimization parameters were used to confirm the optimization method. Finally, a 4th order low pass filter with a cascade structure of biquarts was compared to a 4th order filter without feedback and confirmed to have lower sensitivity.