Implementation Of Control Loop Research Articles

A Resolution Control Loop for TDC-Based Phase Detectors in ADPLLs

This paper proposes a resolution control loop that runs in background to control the time resolution of a mid-rise Time to Digital Converter (TDC) used as a phase detector in All-Digital Phase Locked Loops (ADPLLs). The proposed resolution control loop minimizes the TDC resolution until the TDC linear dynamic range equals the range of the input time error. Consequently, PLL in-band phase noise is reduced due to reduction of the Power Spectral Density (PSD) of the TDC quantization noise. Moreover, the linearity of the TDC transfer function across the range of the input time error is guaranteed. On contrary, the counterpart resolution control loop based on Lloyd-Max algorithm does not guarantee the linearity of the TDC transfer function across the range of the input time error. Furthermore, the proposed resolution control loop achieves TDC quantization noise with a lower variance compared to that achieved by the counterpart resolution control loop when applied with a TDC with more than 3 bits. Finally, the hardware implementation of the proposed resolution control loop is more area and power efficient compared to the implementation of the counterpart resolution control loop.

Comprehensive angular scattering distribution analysis for resource-efficient manufacturing

Most measuring principles for surface topography measurement cannot be broadly used within machine tools due to the rough environment featuring vibrations, dust, cooling liquid, or temperature gradients. Having to measure outside of the machine tool results in large quality control loops. The angular-resolved scattering light sensor is an established measuring principle which can be used directly in the manufacturing environment and thus allows small quality control loops and a resource-efficient manufacturing since deviations in the manufacturing process can be detected almost immediately. For the evaluation of the surface characteristics, the angular distribution of the surface within a lightspot is typically characterized by its center of gravity (M-parameter) and its variance (Aq-parameter) as described in the guideline VDA 2009. These two parameters provide only little information about the angular distribution and the workpiece quality and for certain, function-oriented applications and expanded data analysis can be beneficial to allow the monitoring in more manufacturing systems with high benefits for resource-efficient manufacturing. We suggest using additional parameters of the angular distribution and perform a correlation analysis with the machining parameters of an exemplified manufacturing process to find parameters that feature a more pronounced correlation with the process parameters than Aq and thus allow an improved monitoring of the manufacturing process in this paper. The example process chosen is a grinding process with different tool grit sizes, tool surface speeds, feed rates, and coolant air flow power. With this case study it can be demonstrated how a more comprehensive analysis of the scattering of surface angles can lead to an improved process monitoring since the correlation between the process parameters and the parameters of the angular distribution shows how sensitively different deviations in the process can be detected, e.g. when the grinding belt must be replaced. For an efficient implementation of quality control loops, simple and traceable monitoring parameters are essential. A smart evaluation of the measurement data allows an optimization of the manufacturing process and the associated quality control loops.

Surface topographies from electron optical images in electron beam powder bed fusion for process monitoring and control

Electron optical imaging is a process monitoring method in electron beam powder bed fusion, which enables porosity detection in situ for every layer of a part. The two main defect types occurring in a build process are porosity, due to insufficient local energy input, and surface bulging, when it is too high. This work adds the ability to measure surface topographies quantitatively and in situ to electron optical imaging. To this end, electron optical images are recorded with a four detector system from melt surfaces fabricated on a Ti–6Al–4V plate. A complete computation chain is proposed, based on a developed model of the imaging process. The model explains the correction of image distortions and the calibrated calculation of the gradient information of the respective surfaces. It becomes possible to reconstruct height maps of melt surfaces by the usage of a suitable normal integration algorithm. The computation chain is validated by the comparison of the resulting reconstructions with laser scanning microscope measurements. Electron optical imaging is able to measure porosity and bulging simultaneously, which allows to gain important process information for process control and the future implementation of feedback control loops.

Optical methods for measuring the feature size of optical diffraction gratings with nano-meter accuracy and implementation of suitable feedback control loops

Surface relief diffraction gratings offer a high flexibility in their design and thus allow to synchronize their optical performance with the specific requirements of the underlying application. However, the accuracy and the specific control of the manufacturing processes are of vital importance. In this contribution, we present optical methods relying on white-light ellipsometry and how they can be exploited for the measurement of the critical dimensions of manufactured surface relief grating structures. We will furthermore present suitable processes (relying on atomic layer deposition) and how they are used in a feedback loop to control the grating’s feature sizes on the nanometer scale.

Coherent self-control of free-space optical beams with integrated silicon photonic meshes

In technologies operating at light wavelengths for wireless communication, sensor networks, positioning, and ranging, a dynamic coherent control and manipulation of light fields is an enabling element for properly generating and correctly receiving free-space optical (FSO) beams even in the presence of unpredictable objects and turbulence in the light path. In this work, we use a programmable mesh of Mach–Zehnder (MZI) interferometers to automatically control the complex field radiated and captured by an array of optical antennas. The implementation of local feedback control loops in each MZI stage, without global multivariable optimization techniques, enables an unlimited scalability. Several functionalities are demonstrated, including the generation of perfectly shaped beams with nonperfect optical antennas, the imaging of a desired field pattern through an obstacle or a diffusive medium, and the identification of an unknown obstacle inserted in the FSO path. Compared to conventional devices used for the manipulation of FSO beams, such as spatial light modulators, our programmable device can self-configure through automated control strategies and can be integrated with other functionalities implemented onto the same photonic chip.

Performance of Quad Mass Gyroscope in the Angular Rate Mode.

In this paper, the characterization and analysis of a silicon micromachined Quad Mass Gyroscope (QMG) in the rate mode of operation are presented. We report on trade-offs between full-scale, linearity, and noise characteristics of QMGs with different Q-factors. Allan Deviation (ADEV) and Power Spectral Density (PSD) analysis methods were used to evaluate the performance results. The devices in this study were instrumented for the rate mode of operation, with the Open-Loop (OL) and Force-to-Rebalance (FRB) configurations of the sense mode. For each method of instrumentation, we presented constraints on selection of control parameters with respect to the Q-factor of the devices. For the high Q-factor device of over 2 million, and uncompensated frequency asymmetry of 60 , we demonstrated bias instability of /r and Angle Random Walk (ARW) of / in the OL mode of operation and bias instability of /r and ARW of / in the FRB mode of operation. We concluded that in a realistic MEMS gyroscope with imperfections (nearly matched, but non-zero frequency asymmetry), a higher Q-factor would increase the frequency stability of the drive axis resulting in an improved noise performance, but has challenges in implementation of digital control loops.

Experimental evaluation of negative-sequence voltage compensation in distribution networks by a modular multilevel static synchronous compensator

This paper presents a negative-sequence voltage compensation strategy of a distribution network by using a static synchronous compensator based on modular multilevel converter. Mathematical relations of the static compensator are used to derive small-signal linearised models, in the synchronous reference frame, and to design voltage and current controllers to compensate for unbalanced voltages at the point of common coupling. Moreover, a comprehensive model of the DC bus voltage with a control loop implementation are presented. Furthermore, a notch filter is connected in the feedback path of the DC voltage control loop to eliminate the oscillation in the DC voltage. Digital simulations results, obtained with a 10 MVA / 24 kV MMC-DSTATCOM with 14 submodules per arm, will be used to validate the small-signal linearised mathematical models, and the performance of the designed controllers, during steady-state and faulty grid conditions. In addition experimental results obtained with a small-scale MMC prototype, with 03 submodules per arm, will be presented to demonstrate the feasibility of the compensation strategy proposed here.

МОДЕРНИЗАЦИЯ СИСТЕМЫ УПРАВЛЕНИЯ УЗЛОМ СМЕШЕНИЯ ДИЗЕЛЬНОГО ТОПЛИВА

Based on the analysis of the existing distributed control system of the diesel fuel mixing unit, the imperfection of the control loops of the kerosene fraction, the depressant-dispersant, cetane-increasing and antiwear additives were revealed due to the fact that they do not take into account the quality indicators of commercial diesel fuel if there are in-line analyzers of its characteristics in the automated system. It leads to the need for the operator to participate in the control of the flow rate of these flows. In this regard, the unit was simulated on the basis of experimental and statistical methods, based on the results of which a virtual analyzer of the lubricity of commercial diesel fuel was developed. Proposals have been formulated for the modernization of control loops with the consumption of depressant-dispersant and cetane-increasing additives, kerosene fraction, adjusted for the qualitative characteristics of commercial diesel fuel, as well as the consumption of antiwear additives, corrected according to the results of the readings of the developed virtual analyzer of the lubricity of fuel. Programs for the implementation of modernized control loops in the language of functional blocks of the Centum VP controller have been developed.

Distributed selective harmonic mitigation and decoupled unbalance compensation by coordinated inverters in three-phase four-wire low-voltage networks

Considering the high penetration of distributed generators in low-voltage grids, establishing a coordinated operation of their grid-tied inverters has become imperative to move towards the implementation of smart grids. Yet, knowing that mitigation of power quality issues such as reactive power, current unbalance and harmonics is of importance within such a context, this work proposes a master/slave control approach, which uses a communication means of low-bandwidth, to flexibly coordinate four-leg inverters dispersed in three-phase four-wire networks. Their coordination is attained by means of a current-based approach, allowing the sharing of active, reactive, harmonic and unbalance currents drawn by loads. The control strategy also regulates the power flow at the point of common coupling of the low-voltage network, while proportionally steering inverters according to their nominal capabilities. In addition to the offering of selective harmonic mitigation, the control approach provides distributed and decoupled unbalance compensation, in partial or total portion, based on concepts from the Conservative Power Theory. Consequently, extraction of sequence components or implementation of virtual impedance control loops are not required. The proposed strategy is evaluated based on multiple simulation results, considering the CIGRE's European low-voltage distribution benchmark, including six distributed inverters, as well as linear and nonlinear loads.

The Vehicle Model Acceleration Control for Platooning

The design and implementation of the vehicle acceleration control loop containing a moment of inertia emulator are introduced in this paper. The vehicle is simulated in real-time using a simplified longitudinal one-wheel vehicle model. The model takes into account the road parameters and the effect of air resistance on the vehicles driving performance. The model is designed to reduce the traction force ripple. The acceleration control and the vehicle model are implemented on Simatic Open Controller using MATLAB and SIMATIC Target 1500S. The vehicle drive and the load torque are simulated on the same Open Controller. The properties of the presented implementation are demonstrated by results collected from the Open Controller.

A Structured Methodology for Pattern based Adaptive Scheduling in Embedded Control

Software implementation of multiple embedded control loops often share compute resources. The control performance of such implementations have been shown to improve if the sharing of bandwidth between control loops can be dynamically regulated in response to input disturbances. In the absence of a structured methodology for planning such measures, the scheduler may spend too much time in deciding the optimal scheduling pattern. Our work leverages well known results in the domain of network control systems and applies them in the context of bandwidth sharing among controllers. We provide techniques that may be used a priori for computing co-schedulable execution patterns for a given set of control loops such that stability is guaranteed under all possible disturbance scenarios. Additionally, the design of the control loops optimize the average case control performance by adaptive sharing of bandwidth under time varying input disturbances.

Use Of REX Control System For The Ball On Spool Model

Abstract This paper deals with the design and implementation of linear quadratic controller (LQR) for modeling of Ball on Spool. The paper presents the entire process, starting from mathematical model through control design towards application of controller with the use of given hardware platform. Proposed solution by means of REX Control System provides a high level of user comfort regarding implementation of control loop, diagnostics and automatically generated visualization based on HTML5. It represents an ideal example of a complex nonlinear mechatronic system with a lot of possibilities to apply other types of controllers.

Design and implementation of quality control loops

Purpose – Business processes have an open and dynamic character and are influenced by internal an external disturbances. Without an adequate use of feedback mechanisms, those processes become unstable and do not achieve the expected performance. The purpose of this paper is to face the challenge and to ensure a competitive quality level, a framework for entrepreneurial quality management is given. Design/methodology/approach – Using the method of analogy formation the transfer of cybernetic approaches to business processes is shown. Especially quality control loops are analysed in order to find appropriate solutions for their design and implementation in enterprises. Findings – As a core element of the paper an approach for the systematic implementation of control loops is given. This approach offers a framework and a description for an operative implementation of quality control loops for stable business processes. Originality/value – The idea to use closed quality control loops for the design of several processes is already known. Anyway, both a robust framework and a appropriate, sufficient and detailed description for an operative implementation is the new aspect and an important further development within the topic.

Modular Design Approach for Model-Based Drive Control Systems on Reconfigurable Logic

Architectures based on reconfigurable hardware, notably FPGAs, are an emerging trend in signal processing applications. For industrial control systems, the benefits of this technology, real parallelization combined with flexibility, offer a great potential. Regarding drive controls, reconfigurable hardware can be used to implement sophisticated control loops for which state of the art processor-based platforms are not performant enough. This capability was verified using FPGA-based prototyping systems, providing easy to use development processes.However, to date, no standard industrial drive control utilizes and benefits from this technology. A key factor for this is that besides the design of the control loop itself, its integration into a drive control system is crucial for industrial use, including functional, process, communication and safety aspects. While available tools are focused on the control loop implementation, the latter requirements are not currently fulfilled.In the context of the presented research, a new module-based approach was developed, providing a holistic solution for all the requirements. Thereby, the design of a control loop is based on basic blocks which not only provide the mathematical functionality, but also features to fit into a drive control system. Furthermore, a drive control architecture providing a flexible design space is presented, in which the modular approach can be used.

Autonomic care platform for optimizing query performance

BackgroundAs the amount of information in electronic health care systems increases, data operations get more complicated and time-consuming. Intensive Care platforms require a timely processing of data retrievals to guarantee the continuous display of recent data of patients. Physicians and nurses rely on this data for their decision making. Manual optimization of query executions has become difficult to handle due to the increased amount of queries across multiple sources. Hence, a more automated management is necessary to increase the performance of database queries. The autonomic computing paradigm promises an approach in which the system adapts itself and acts as self-managing entity, thereby limiting human interventions and taking actions. Despite the usage of autonomic control loops in network and software systems, this approach has not been applied so far for health information systems.MethodsWe extend the COSARA architecture, an infection surveillance and antibiotic management service platform for the Intensive Care Unit (ICU), with self-managed components to increase the performance of data retrievals. We used real-life ICU COSARA queries to analyse slow performance and measure the impact of optimizations. Each day more than 2 million COSARA queries are executed. Three control loops, which monitor the executions and take action, have been proposed: reactive, deliberative and reflective control loops. We focus on improvements of the execution time of microbiology queries directly related to the visual displays of patients’ data on the bedside screens.ResultsThe results show that autonomic control loops are beneficial for the optimizations in the data executions in the ICU. The application of reactive control loop results in a reduction of 8.61% of the average execution time of microbiology results. The combined application of the reactive and deliberative control loop results in an average query time reduction of 10.92% and the combination of reactive, deliberative and reflective control loops provides a reduction of 13.04%.ConclusionsWe found that by controlled reduction of queries’ executions the performance for the end-user can be improved. The implementation of autonomic control loops in an existing health platform, COSARA, has a positive effect on the timely data visualization for the physician and nurse.

Design and assessment of quality control loops for stable business processes

Due to their open and dynamic character, business processes in lack of adequate feedback mechanisms tend to become unstable in case of unanticipated disturbances or target adjustments. In order to face this challenge and to ensure entrepreneurial quality the implementation of quality control loops is proposed, whose design is derived from cybernetics. The paper discusses requirements for the characteristics of quality control loops and presents a new approach for their assessment implemented in software. The developed tool also serves as a knowledge exchange platform since it provides an opportunity for exchanging standardized control loop elements.

Closed Control Loop Implementation for Single Robot Axis on FPGA Platform

This paper deals with closed control loop implementation for robot single axis with DC motor on FPGA platform. Controlling algorithm is designed in Matlab/Simulink environment and its Custom Toolbox is specifically designed for the purpose of control structures development in real time. Torque is calculated on FPGA structure and brought to a motor which generates necessary PMW. On the motor axis is a pendulum which follows default trajectory. It is a stream of data obtained by calculating or recording robot axis position while moving it manually. Experimental results are also provided.

MIMO Modeling Approach for a Small Photovoltaic Reverse Osmosis Desalination System

The most widely used desalination processes are based on membrane separation via reverse osmosis (RO) which has become an important process for desalting seawater and cleaning brackish water. The use of these processes requires an efficient control system. Consequently, it is necessary to establish a dynamic model of the system with experimental validation. This paper deals with a new modelling approach of a small photovoltaic reverse osmosis (PV-RO) desalination unit. The proposed model considers the unit as a Multi Input Multi Output (MIMO) process. The relations between the output variables and the input variables are given by the use of empirical transfer matrix. A state model of the unit is also given. Some experimental results are presented to validate the proposed model. As result, the obtained unit model can be easily used for a process control loop implementation in order to assure an optimum operating condition and to reduce the water product cost.

A high-efficiency fully digital synchronous buck converter power delivery system based on a finite-state machine

A fully digital, self-adjusting, and high-efficiency power supply system has been developed based on a finite-state machine (FSM) control scheme. The system dynamically monitors circuit performance with a delay line and provides a substantially constant minimum supply voltage for digital processors to properly operate at a given frequency. In addition, the system adjusts the supply voltage to the required minimum under different process, voltage, and temperature and load conditions. The design issues of the fully digital power delivery system are discussed and addressed. This digital FSM scheme significantly reduces the complexity of control-loop implementation (<1800 gates) and power consumption (< 100 /spl mu/W at 1.2 V) compared to other approaches based on proportional-integral-differential control. The power delivery control system is fabricated in a 0.13-/spl mu/m CMOS process and its core die size is 160 /spl times/ 110 /spl mu/m/sup 2/.

Design and implementation of differential pulsewidth control loop for GHz VLSI systems

A novel differential pulsewidth control loop (PWCL) is proposed, in which a balanced charge pump is employed so that the PWCL does not require a 50% duty cycle reference clock. A test chip is realised in a 0.35 µm CMOS process, and the measured results show that the tuning range for the duty cycle of the input clock is from 27 to 71% at 1 GHz operating frequency.