High Precision Output Research Articles

Tracking control of non-minimum phase systems: a kernel-based approach

Feedforward control with model inversion is a widely-used solution for high-precision output tracking. However, because inverting a non-minimum phase model generates unbounded control input, model-inversion only applies to limited types of systems. This paper presents a new non-parametric pseudo-inversion approach to design bounded optimal control input with desirable properties for arbitrary types of systems. Closed-form equations are presented for the batch (full preview) and recursive (limited preview) implementations of this approach, and its performance is compared against existing pseudo-inversion methods in benchmark numerical examples. Furthermore, the practical implementation of the proposed method is demonstrated by designing a feedforward controller for a commercial 3-Dimensional (3D) printer. The results show that the proposed approach effectively compensates for the structural vibrations of the printer, preventing layer-shifting errors that usually happen during high-speed printing.

Model-free compensation learning control of asymmetric hysteretic systems with initial state learning

In this article, a model-free compensation learning control scheme is presented for asymmetric hysteretic systems to achieve high-precision output tracking, where the effects of asymmetric input hysteresis nonlinearities are denoted by the asymmetric Prandtl–Ishlinskii model (APIM). In the presented control scheme, the feedforward iterative learning technique is generalized to the control design of asymmetric hysteretic systems. To improve the robustness and dynamic performance of the existing feedforward learning control for hysteretic systems, both the feedback action and the differential term are utilized to design a discrete-time PD-P open-closed-loop learning control law for simultaneously compensating the asymmetric input hysteresis nonlinearities and the linear dynamics effects without constructing compensators based on their models. The initial state error of such a system is also considered, a modified initial state learning strategy is proposed to ensure the initial state error tends to a prescribed level with the increasing of iterations. By fully analyzing the properties of the APIM, the convergence conditions with respect to the input error, the state error, and the tracking error along the iteration domain are given. The simulation and experimental results are provided to demonstrate strong robustness and excellent tracking accuracy with the proposed model-free compensation learning control scheme.

Triboelectric nanogenerator based on multi-component crosslinked network hydrogel for intelligent human motion sensing

With the continuous development of intelligent wearable devices, new requirements are put forward for the collection of human motion information. In this paper, a self-powered motion sensor with high precision, high stability and high output power was prepared by utilizing the flexibility and stretchability of the conductive hydrogel and combining with the nanogenerator. Even at a contact frequency of 3.0 Hz, the sensor can produce an open circuit voltage of 225 V and a power density of 187 mW m−2. It can not only be used as a power source to drive electronic devices, but also to achieve accurate acquisition of human movement steps and walking speed. When applying different forces, the sensor shows a more obvious difference, and its theoretical resolution can reach 0.1 N. Because the hinge hydrogel has good flexibility, resilience and stability, it can still maintain its original shape after 4000 times of pressure testing, and can be directly attached to the human skin surface, providing a new idea for the field of self-powered pressure sensors.

Design and implementation of high precision servo channel loading card for fatigue testing of aircraft wings

SummaryA servo channel loading card (SCLC) with high precision data acquisition and output is developed for static and fatigue testing of aircraft wings. A high‐performance processor field programmable gate array (FPGA) is at the core to control the excitation source (ES) output circuit to provide excitation for the force and displacement sensor. To improve the precision of the ES output circuit, a 3DA‐based ES auto‐calibration circuit is designed. Simulation results show that the 3DA improves the precision of the automatic calibration of the ES circuit. The sensor signals are collected through high precision analog channels, and the signals are automatically zero calibrated and numerical control gain processed. Ultimately, a voltage or current signal is generated through the drive circuit to control the electro‐hydraulic servo loading system to complete a high precision force loading test on the aircraft wings. The experimental results show that the board designed has high reliability in both acquisition and output. The ES output achieved a precision of 0.1375 mV/V, the precision of signal acquisition achieves a precision of −0.175 mV/V, and the servo drive output achieves a precision of −0.06 mV/V, meeting the expected design precision of 1 mV/V.

Design of a High Precision RC Oscillator

This paper introduces a high-precision RC oscillator circuit that is less affected by temperature and supply voltage. The circuit mainly consists of a bandgap reference voltage source, a low-voltage linear regulator, a low-pass filter, and a digital trim circuit, which reduces the circuit's sensitivity to temperature variations and achieves high stability of the oscillator frequency over a wide temperature range. Because of the current digital trimming technique, the circuit's ability to cope with the effects of frequency instability caused by process deviations is further enhanced.The simulation results show that the output center frequency accuracy is maintained within ±0.5% under the supply voltage range of 2.5V~5.5V, temperature range of -40?~125?, and different process corners. The RC oscillator has a high precision output frequency and can be used as a clock signal for a number of highly integrated and high precision applications.

Spatial sigma-delta modulation for coarsely quantized linear, circular, and spherical arrays

Quantization noise shaping, also known as sigma-delta modulation, is widely used in analog-to-digital converters. Such converters oversample a signal in time, quantize it to one or a few bits of precision, and then use analog feedback to shape quantization noise outside the band of interest, producing a high-precision output. Similarly, if a sensor array is spatially oversampled so that its elements are much less than one-half wavelength apart, then quantization noise can be propagated between channels to shape its spatial distribution. A beamformer acts as a spatial filter, removing shaped quantization noise to produce a high-precision output even with coarsely quantized sensors. Spatial sigma-delta modulation has been explored primarily for radio-frequency applications using linear arrays. In this presentation, we apply spatial noise shaping to dense acoustic sensor arrays, including circular and spherical arrays. For immersive audio applications, we demonstrate how noise-shaping feedback can be used to push quantization noise into higher-order Ambisonic modes.

High-precision bus voltage control based on NLESO and TSMC predicted load current and grid voltage differential feedforward

Power battery test equipment is widely used to produce and test new energy vehicles and storage containers. To address the problem of DC bus voltage fluctuations that affect the accuracy of output voltage and current, a high-accuracy bus voltage control strategy is based on nonlinear extended state observation (NLESO) and terminal silding mode controller (TSMC) load current estimation. Simulation and experimental results show that the control strategy has a good suppression effect on the DC bus voltage fluctuation and can effectively improve the accuracy of the DC side output voltage and current. Grid voltage differential feedforward is adopted, which can achieve fast suppression of DC bus voltage fluctuations in power battery test equipment and meet the high precision output requirements of the system DC bus.

High Precision Primary Side Regulation Constant Voltage Control Method for Primary and Secondary Resonant Active Clamp Flyback Converter

Active clamp flyback (ACF) converter has been demonstrated that which is better than traditional flyback in high-frequency power-adaptor applications. According to the circuit structure, ACF has two modes, primary resonant ACF (PR-ACF) and secondary resonant ACF (SR-ACF). In order to improve the power density, a high-precision primary side regulation (PSR) constant voltage control method for ACF converter is proposed in this article. The proposed method not only can be effectively adopted in PR-ACF but SR-ACF converter. The high-precision output voltage is predicted by highly accurate sampling points on primary auxiliary voltage. The applied microcontroller environment improves the practicability and increases the power density of the ACF system. To verify the proposed PSR method, a prototype that can be changed into PR-ACF and SR-ACF is designed. The output voltage offset, operation efficiency, and dynamic performance are analyzed. The tested results show that high-precision output is obtained in ACF converter by using the proposed method and the maximum output voltage deviation which are 4% and 3.5% in PR-ACF and SR-ACF converter, respectively. Moreover, SR-ACF has a higher efficiency compared with PR-ACF converter, and a smaller voltage shoot during dynamic process, which needs a larger regulation time since the additional output inductor.

A Frequency Measurement Method for Protection of Smart Circuit-breaker

The application scale of new energy such as wind energy and solar energy in China is increasingly large. One of the characteristics of these energy sources is instability. Circuit-breakers play an important role protection in distributing these energy sources. Aiming at a new type of smart circuit-breaker architecture, this paper proposes a frequency measurement method for protection function, that is, the waveform sample value of high precision and high sample rate output by the DMA of the metering chip. The FIR filter is used to eliminate harmonic interference, impulse interference, etc of sample value. The frequency value is calculated by the interval duration between the two cross-zero points of sample value, and the simulation process, as well as the results, are given.

A 5 V-to-32 V Input PVT-Robust Charge-Pump Circuit with Adjustable Output in a 0.18 μm BCD Process

In this paper, a new closed-loop charge-pump circuit with adjustable output voltage and an on-chip compensation technique is proposed. The environmental temperature and process corner can be detected with an on-chip detection circuit and automatically feedback an adjusted reference voltage. With this, the magnitude of the charge-pump output voltage with Pulse-Width Modulation (PWM) can be compensated. The charge-pump circuit is designed and verified with a 180 nm Bipolar-CMOS-DMOS (BCD) process, and its output voltage at different process, voltage, and temperature (PVT) is controllable with low ripple. There are three selections for adjusting the output voltage: +5 V/+7 V/+10 V shifts, with the supply voltage ranging from 5 V to 32 V. It can remain tunable and stable at any shifts. The maximum deviation is ±0.265%, and the maximum load current can reach 30 mA. The ripple voltage is less than 0.3% (Δ Vripple/Vout) underthe maximum load. The Monte Carlo simulation results show that the worst case of the process sensitivity (σ/μ) is 0.1%. The charge-pump core area is 0.308 mm2, and the power consumption is 4.753 mW. The circuit can produce high-precision output and is suitable for high-side driving IC applications.

Research on Maximum Efficiency Output Control of Voltage Controlled Adjustable Constant Current Source

Voltage controlled adjustable constant current source has simple structure and high output precision, but its high switching power consumption and low output power efficiency under current variation hinder the development of its high current application. A maximum efficiency output control method of constant current source based on small signal model is presented to reduce switching loss and achieve high efficiency output. A 0-4A adjustable constant current source prototype was built to verify the theory, and the experimental results show that when the setting current changes from 1 to 4A, the output dynamic response of the experimental group is rapid, the instantaneous peak power of MOS transistor is only 6.04w, and compared with the control group, the average efficiency of the system is from 85.85% up to 92.86%, which indicate a better power consumption control ability.

Gimbal Angular Velocity Feedforward Method for Magnetically Suspended Control Moment Gyro with Hybrid Magnetic Bearing#

Control moment gyro(CMG) has the advantages of high precision and large output moment. It is the key actuator of agile spacecraft attitude control system. Magnetically suspended CMG(MSCMG) supports high-speed rotor through magnetic bearing, which has the advantages of no friction, no wear, high precision and long life. Hybrid magnetic bearing(HMB) generates bias magnetic field by replacing bias current with permanent magnet, which greatly reduces the power consumption. However, when MSCMG output moment, moving-gimbal effect makes the control current of HMB increase sharply, which result in the rapid increase of power consumption. To solve this problem, gimbal angular velocity feedforward(GAVF) method is proposed in this paper. Firstly, the model of HMB-rotor system containing moving-gimbal effect is established. Secondly, GAVF method is introduced to make the rotor deflect by designing a feedforward matrix with gimbal angular velocity and stiffness of HMB which is determined with rotor deflection angle and rotation speed. Thus, the gyroscopic moment is mainly offset by the bias magnetic field of HMB. Finally, an adaptive compensation method based on GAVF is proposed to maintain the system performance under parameter perturbation. By the above, the power consumption of control current during moment output process is reduced. Simulation and experiment results show the effectiveness of the proposed method.

Modeling, Analysis, and Development of a Current Decoupling Control High-Precision Converter Under Nonideal Conditions

In order to ensure that the inductors of dual-buck full-bridge converter (DBFBC) can operate in continuous conduction mode (CCM), the bias current and output current are decoupled and controlled independently, and it makes the converter obtain high-precision output current. Present analytical models are established on the ideal conditions and the effect of nonideal conditions on decoupling control is not considered. At first, in order to analyze the mechanism of current error under nonideal conditions, the state-space average model with equivalent parameters of DBFBC is established. Then, the cross coupling caused by incomplete decoupling under nonideal conditions is analyzed, and the expression between equivalent parameters and current error is derived. Furthermore, the features of bias current and output current error caused by cross coupling are analyzed, and the corresponding restraining method is proposed. Finally, the experimental results are presented to verify the theoretical analysis.

Zero-Aware Low-Precision RNS Scaling Scheme

Scaling is one of the complex operations in the Residue Number System (RNS). This operation is necessary for RNS-based implementations of deep neural networks (DNNs) to prevent overflow. However, the state-of-the-art RNS scalers for special moduli sets consider the 2k modulo as the scaling factor, which results in a high-precision output with a high area and delay. Therefore, low-precision scaling based on multi-moduli scaling factors should be used to improve performance. However, low-precision scaling for numbers less than the scale factor results in zero output, which makes the subsequent operation result faulty. This paper first presents the formulation and hardware architecture of low-precision RNS scaling for four-moduli sets using new Chinese remainder theorem 2 (New CRT-II) based on a two-moduli scaling factor. Next, the low-precision scaler circuits are reused to achieve a high-precision scaler with the minimum overhead. Therefore, the proposed scaler can detect the zero output after low-precision scaling and then transform low-precision scaled residues to high precision to prevent zero output when the input number is not zero.

SuperMeshing: A New Deep Learning Architecture for Increasing the Mesh Density of Physical Fields in Metal Forming Numerical Simulation

AbstractIn metal forming physical field analysis, finite element method (FEM) is a crucial tool, in which the mesh-density has a significant impact on the results. High mesh density usually contributes authentic to an increase in accuracy of the simulation results but costs more computing resources. To eliminate this drawback, we propose a data-driven mesh-density boosting model named SuperMeshingNet that uses low mesh-density physical field as inputs, to acquire high-density physical field with 2D structured grids instantaneously, shortening computing time and cost automatically. Moreover, the Res-UNet architecture and attention mechanism are utilized, enhancing the performance of SuperMeshingNet. Compared with the baseline that applied the linear interpolation method, SuperMeshingNet achieves a prominent reduction in the mean squared error (MSE) and mean absolute error (MAE) on the test data. The well-trained model can successfully show an improved performance than the baseline models on the multiple scaled mesh-density, including 2 ×, 4 ×, and 8 ×. Enhanced by SuperMeshingNet with broaden scaling of mesh density and high precision output, FEM can be accelerated with seldom computational time and cost with little accuracy sacrificed.

Development of a Novel three degree of freedom XYθZ Micro-Motion Stage

Background: The piezoelectric motion with multi-degree of freedom is gaining attention in industries for modern manufacturing. High degree of positioning accuracy is obtained by complaint micro machining stages which involves high cost. A variety of stages of multi-degree motion freedom are proposed and applied for decades which can perform very high precision outputs in a wide travel range. Methodology: This paper mainly focuses on design, development and analysis of the 3 DOF (Degree of Freedom) XYqZ micro-motion stage. The role of each component of the stage is discussed. The various design processes are discussed and includes the discussion about the inputs to the design process as well as the constraints; both of which are dependent on the application for which the stage is used. Based on the design rules, an iterative optimization process is implemented and three design options are presented. Findings: The finite element modeling of all the design options are carried out. This is followed by performing deformation, static, fatigue and modal analysis on the three design options. The deformation analysis predicts that design 1 and design 2 offer a workspace of around 210 µm each along (X, Y) direction and 25 µrad along the Z direction while design 3 has deformation of 125 µm each along (X, Y) direction while 25 µrad along Z direction where as the fatigue analysis presented shows the life of around 105 cycles. Novelty: Using this technique the micro-motion stage is achieved for three degrees of freedom. Keywords Micro motion stage, flexure hinges, modeling, 3 degrees of freedom

Lifetime improvement of digital microfluidic biochips based on the IWOA

Digital microfluidic biochips (DMFBs) are increasingly important used for clinical diagnostics drug discovery and point-of-care. Those procedures require high output precision, so the reliability and lifetime of the chips are extremely important. Due to the inherently reconfigurable nature of DMFBs, a degraded electrode may be reused many times. Therefore, the lifetime of the chips is closely related to the total actuation time of an electrode. Thus, the electrode total actuation time needs to be considered carefully in an efficient DMFB design process. This paper proposes an improved whale optimization algorithm (IWOA), which can reduce the excessive use of an electrode and reuse electrodes in an average manner to optimize the longest lifetime of DMFBs. First, the IWOA combined a WOA with a genetic algorithm, and inertial weights were added to enhance the local search ability of the IWOA. Second, the max-min WOA was proposed in the exploration phase. Lastly, the position mass of individual whales was improved to represent the sequence of operations. The simulation experimental results showed that this algorithm was able to solve lifetime optimization problems. The efficiency and convergence performance of the algorithm were very good. The proposed algorithm can achieve maximum improvement in the maximum electrode activation time of 74.6%, 8.2%,15.7% and 7.2% respectively, compared with T-trees algorithm, 3-DDD algorithm, PRSA algorithm and 3D-DDMS algorithm.

Development of a Non-invasive Deep Brain Stimulator With Precise Positioning and Real-Time Monitoring of Bioimpedance

Methods by which to achieve non-invasive deep brain stimulation via temporally interfering with electric fields have been proposed, but the precision of the positioning of the stimulation and the reliability and stability of the outputs require improvement. In this study, a temporally interfering electrical stimulator was developed based on a neuromodulation technique using the interference modulation waveform produced by several high-frequency electrical stimuli to treat neurodegenerative diseases. The device and auxiliary software constitute a non-invasive neuromodulation system. The technical problems related to the multichannel high-precision output of the device were solved by an analog phase accumulator and a special driving circuit to reduce crosstalk. The function of measuring bioimpedance in real time was integrated into the stimulator to improve effectiveness. Finite element simulation and phantom measurements were performed to find the functional relations among the target coordinates, current ratio, and electrode position in the simplified model. Then, an appropriate approach was proposed to find electrode configurations for desired target locations in a detailed and realistic mouse model. A mouse validation experiment was carried out under the guidance of a simulation, and the reliability and positioning accuracy of temporally interfering electric stimulators were verified. Stimulator improvement and precision positioning solutions promise opportunities for further studies of temporally interfering electrical stimulation.

Design of high precision and high power bidirectional adjustable power supply

Abstract ITER (International Thermonuclear Experimental Reactor) sensor steady-state test platform needs high power supply with high steady-state precision output voltage. In the field of high voltage power supply applications, there is often a contradiction between the power supply capability and the switching frequency of high power switching devices. Limited by switching loss, the switching frequency of high power switching devices is low, which will generate a lot of harmonic in the output voltage. In order to meet the requirement of power supply for high-precision output voltage, the design of high power supply adopts the method of combining H-bridge cascaded topology with carrier phase shift PWM control scheme, which can effectively improve output voltage waveform in the design of high power supply. The harmonic analysis and simulation are carried out, and the experimental results verify the validity of the experimental scheme.

Robust Digital Nonlinear Control System for Dual Active Bridge (DAB) DC/DC Converters With Asymmetric Half-Cycle Modulation

This article presents a new digital control system for dual active bridge dc/dc converters. The proposed control system includes a novel compensator with asymmetric half-cycle modulation. The proposed compensator is based on a novel geometric-sequence-control algorithm, which is a model-based predictive current control. The proposed control system provides fast and seamless tracking of the reference current and ensures zero dc current in the transformer windings (prevents transformer saturation). Moreover, it offers high robustness against perturbations and uncertainties in the converter. It also allows symmetric growth of transformer current during transients, thereby eliminating potential temporary saturation issues. Analysis, simulation, and experimental results are provided to demonstrate the superior performance of the proposed control in achieving high precision output regulation, fast and seamless transient response, and high robustness.