Simple Control System Research Articles

Safe Controller Synthesis With Tunable Input-to-State Safe Control Barrier Functions

To bring complex systems into real world environments in a safe manner, they will have to be robust to uncertainties-both in the environment and the system. This letter investigates the safety of control systems under input disturbances, wherein the disturbances can capture uncertainties in the system. Safety, framed as forward invariance of sets in the state space, is ensured with the framework of control barrier functions (CBFs). Concretely, the definition of input-to-state safety (ISSf) is generalized to allow the synthesis of non-conservative, tunable controllers that are provably safe under varying disturbances. This is achieved by formulating the concept of tunable input-to-state safe control barrier functions (TISSf-CBFs), which guarantee safety for disturbances that vary with state and, therefore, provide less conservative means of accommodating uncertainty. The theoretical results are demonstrated with a simple control system with input disturbance and also applied to design a safe connected cruise controller for a heavy duty truck.

ПЕРЕСТАНОВОЧНОЕ ДЕКОДИРОВАНИЕ В МАЛОМОЩНЫХ БЕСПРОВОДНЫХ СЕНСОРНЫХ СЕТЯХ

Wireless sensor networks are currently considered for many subject areas as effective communication systems, including, for example, industrial and agricultural facilities and enterprises, monitoring of sensors of transport security systems, medicine applications, environmental and weather monitoring, etc. In such systems, the correction code (CC) is a classic approach used to increase the reliability of the data transmission channel while simultaneously reducing the required transmitted signal power, called the energy gain code. At the same time, the power of the transmitter is reduced due to additional power consumption in the receiver decoder. Stronger codes provide better performance with lower power requirements, but have more complex decoders with higher power consumption than relatively simple error control systems. If the additional power consumption at the output of the decoder exceeds the savings in transmitted power due to the use of CC, then such a code will not be energy efficient compared to a system with a non-redundant code. Various codes can be used to protect data, while the best codes for which the critical distance turns out to be large according to a number of studies are codes with a low parity check density. The paper proposes an alternative variant based on the synthesis of a permutation decoding system using the method of localization of a limited number of permutations and the organization of additional parity checks exclusively for the verification bits of the CC using the Bayesian approach to iterative transformations of integer soft solutions of symbols.

Control of series impedance of power lines using power flow controller

In this paper, the possibility of unified power flow controller (UPFC) to modulate both series resistance R and series reactance X of an overhead power line is discussed. The classical power flow control system of the UFPC is modified in the manner that standard input references signals (active and reactive powers) are replaced by reference signals of series resistance and reactance. Using the procedure described in this work, the reference signals for active and reactive powers are generated indirectly. The operation of UPFC in proposed operation mode is analyzed using computer simulation, based on a model of single machine infinite bus (SMIB) with constant impedance loads and two parallel lines. The goal is to show that UPFC is capable to control both series line parameters (R and X) directly and independently by means of a simple control system without additional decoupling controllers. An additional task is to show that power flows can be indirectly controlled this way. The step response of series line resistance and reactance is used to validate the operation of the proposed control system. The obtained results clearly show that all goals are fulfilled.

Design And Control of Patient Bed For Prevention Pressure Ulcers in Long-Term Inpatients

Pressure ulcers cause a lot of pain and discomfort in the patient. It also has a negative impact on the quality of life. Some patient’s treatment process may be take longer in hospitals. Like accident injuries, orthopedic treatments, long-term oncologic treatments. In these processes the time that spent on patient beds is very important. These patients must not be moved while the healing process. Especially elderly patients’ and in these long-term patients some bed injuries may occur because of the pressure on their body named bed sores. Due to the negative effects of pressure ulcers on patients and costly treatment, they must be prevented. Controlling the pressure intensity can help prevent pressure ulcers. Currently, the solutions to prevent pressure ulcers include using different methods for movement and displacement of patients. In this study, a patient bed has been designed to prevent pressure ulcers in long-term inpatients as application of electronics in medicine. In this bed, several plastic balls placed on pressure points. These points are the most pressurized points of the human body. The control of pressure in this points to be implemented in real time by an arduino mega controller board. Then the simplified control system is tested on the designed bed. The air inside the airbags placed at the pressure points according to the pressure sensor values connected to the designed system is changed by the compressor. It has been observed that the pressure values decreased by an average of 8-11% by inflating the balls at the pressure points in the designed patient bed system In this way, pressure ulcers occurring at pressure points can be reduced and pressure ulcers can be prevented.

Hardware-in-the-loop simulation of DC motor as an instructional media for control system design and testing

Instructional media in control systems typically requires a real plant as an element to be controlled. However, this real plant, which is costly to be implemented, can be replaced by a virtual plant implemented in a computer and modelled in such a way that it resembles the behavior of a real plant. This kind of set-up is widely termed as hardware-in-the-loop (HIL) simulation. HIL simulation is an alternative way to reduce the development cost. A virtual plant is easy to adjust to represent various plants or processes that are widely used in industry. This paper proposes a simple HIL simulation set-up designed as instructional media for design and testing a simple control system. The experimental result on DC motor control shows that HIL simulation dynamical response is similar to the real hardware response with a small average error on measured transient response, represented in 0.5 seconds difference in settling time and 7.43 % difference in overshoot. This result shows the efficacy of our HIL simulation set-up.

Laboratory Stand for Simplified Verification of Missile Dynamics for Didactic Purposes

Abstract The purpose of this study was to describe dynamics of missile based on bibliography, simplify the model to the easiest form, and verify it with the use of a designed laboratory stand. Next, a simple control system of the missile was designed. The stand is prepared for didactic purposes. A mathematical model was derived by applying Newton's second law together with the earth's coordinate system and the base coordinate system. Parameters of the actual rocket model were determined using the created laboratory stand. Synthesis of the rocket roll system was designed using Simulink PID Tuner application (MathWorks, Inc. Natick, Massachusetts, USA). A control system was based on a proportional-integral (PI) regulator. The designed control system was subjected to simulated tests in MATLAB Simulink (MathWorks, Inc. Natick, Massachusetts, USA).

Energy Management of a Renewable Hybrid Isolated DC Microgrid

Abstract: Hybrid microgrid is the key solution to energize remote rural areas. The microgrid system incorporates more than one Distributed Renewable Energy (DRE) source to complement one another. This paper proposes a hybrid DC microgrid system to be operated in isolated mode. The proposed microgrid consists of a PMSG based Wind Turbine, PV array, and Lead-acid battery as an energy storage device. The Wind Turbine generator is connected to the DC bus through a Three-phase Diode Bridge Rectifier. The PV array is tied to the DC bus by a Boost converter and incremental conductance algorithm is used to extract the maximum power from the PV array. The battery uses a bidirectional converter for charging and discharging. A simple PI-based closed-loop control system is incorporated for proper energy management. The bus voltage is maintained either by the boost converter or the bidirectional converter depending upon the operating condition. The proposed microgrid system is modeled in MATLAB/SIMULINK software. Simulation of this model is done for varying irradiance, temperature, wind condition, and different load condition. The simulation results show that the system is stable under various load and supply conditions. Keywords: Hybrid microgrid, Distributed Renewable Energy (DRE), PMSG, PV array, DC bus, Boost converter, incremental conductance, bidirectional converter

Voltage Sensorless Control of Split Capacitor for Three-Phase Four-Wire Motor System With Zero-Sequence Suspension Winding

This article aimed to simplify magnetically levitated motor system by implementing the voltage sensorless control of the split capacitor potential for a three-phase four-wire motor system with a zero-sequence suspension winding. In the system, the suspension winding for magnetic suspension is connected between the neutral point of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Y</i> -connected three-phase motor winding and the midpoint of two capacitors of direct-current (dc) link, thereby enabling simultaneous control of a three-phase interior permanent magnet synchronous motor and an axial magnetic bearing (iron-ball magnetic suspension, in this article), with only six power switches. However, the split capacitor potential is unbalanced by the dc component of the zero-sequence current, owing to the offset detection error of the current sensor and the bias current of the magnetic suspension. For suppressing the imbalance, we propose a voltage sensorless control. In the proposed method, the split capacitor potential is controlled without voltage detection by utilizing the zero-sequence voltage reference in the controller. The experimental results demonstrated that the split capacitor potential was successfully balanced while the iron-ball magnetic suspension and motor drive were performed. For further improvement of voltage sensorless control, a simplified control system was configurated with a filter controller based on an equivalent block diagram. The results indicated that the use of the filter controller improved the positioning accuracy of the magnetic suspension for the sensorless control system.

Influence Mechanism of Electromechanical Parameters on Transient Dynamics of FWD-EVs: Part I: Co-Modeling of IWM and Vehicle System

In-wheel motor (IWM), as an ideal power source of independent four-wheel drive electric vehicles, has been paid more and more attention due to its high-power density, low starting current, wide speed adjustment range, simple control system and robustness. However, the electromechanical issue is enlarged in both longitudinal and vertical because of in-wheel driven scheme. In this paper, the electromagnetic multi-field characteristic of IWM is investigated based on Fourier series method. The negative vibration coupling on vehicle dynamics is discussed by proposing a conjoint electromechanical FWD-EV model. Results shows that the motor incentive coupled with the vehicle system in multi-degree of freedom, caused the body and wheel resonance in the low speed, meanwhile deteriorated the anti-rollover capability of the IWM-EV in the high speed.

Hydrodynamic Bearing Structural Design of Blood Pump Based on Axial Passive Suspension Stability Analysis of Magnetic–Hydrodynamic Hybrid Suspension System

Rotor suspension stability is one of the important performance indexes of a blood pump and the basis of determining whether the blood pump can be used in a clinic. Compared with the traditional magnetic suspension system, a single-winding, bearingless motor has the advantages of a compact structure, simple control system and low power consumption. In this pursuit, the present study aimed to envisage and design the magnetic suspension system coupled with a single-winding bearingless motor and permanent magnet bearings, establish the theoretical models of axial force and electromagnetic torque, and calculate the stiffness of the magnetic suspension system at the equilibrium point. Addressing the problem of the negative axial stiffness of the magnetic suspension system being negative, which leads to the instability of the suspension rotor, the hydrodynamic bearing structure was proposed and designed, and the critical stiffness to realize the stable suspension of the rotor was obtained based on the stability criterion of the rotor dynamics model. The optimal structural parameters of the hydrodynamic bearing are selected by integrating various factors based on the solution of the Reynolds equation and a stiffness analysis. Furthermore, the vibration experiment results proved that the blood pump rotor exhibited a good suspension stability, and the maximum offset under the impact external fluid was no more than 2 μm.

Simplified feedback control system for scanning tunneling microscopy.

A Scanning Tunneling Microscope (STM) is one of the most important scanning probe tools available to study and manipulate matter at the nanoscale. In a STM, a tip is scanned on top of a surface with a separation of a few Å. Often, the tunneling current between the tip and the sample is maintained constant by modifying the distance between the tip apex and the surface through a feedback mechanism acting on a piezoelectric transducer. This produces very detailed images of the electronic properties of the surface. The feedback mechanism is nearly always made using a digital processing circuit separate from the user computer. Here, we discuss another approach using a computer and data acquisition through the universal serial bus port. We find that it allows successful ultralow noise studies of surfaces at cryogenic temperatures. We show results on different compounds including a type II Weyl semimetal (WTe2), a quasi-two-dimensional dichalcogenide superconductor (2H-NbSe2), a magnetic Weyl semimetal (Co3Sn2S2), and an iron pnictide superconductor (FeSe).

Transfer matrix modeling on a longitudinal-bending coupled piezoelectric transducer with single-phase excitation: Analysis and verification.

Surface-bonded type piezoelectric transducers have the advantages of simple structure, easy miniaturization, and flexible designand have been widely employed as the stator of ultrasonic motors. In order to simplify the control system, a surface-bonded type single-phase excited piezoelectric transducer operating in the longitudinal-bending coupling vibration is proposed, modeled, and validated in this study. Using the asymmetrical excitation effect, the longitudinal-bending coupled vibration is generated in the proposed piezoelectric transducer only applied with a single-phase electrical signal, leading to the production of the elliptical motion at its driving tip. The proposed transducer holds the advantages of compact structure, simple control system, and low manufacturing costs. The transfer matrix method, which is an efficient and fast semi-analytic computation solution, is employed to develop a dynamic model for the proposed transducer in this study in order to provide a general modeling method for surface-bonded type piezoelectric transducers operating with the longitudinal-bending coupled vibration. A novel longitudinal-bending coupled vibration transfer matrix is created first for surface-bonded type piezoelectric composite element. Then, a general semi-analytical electromechanical coupling model is developed to analyze dynamic behaviors of the proposed piezoelectric transducer. Finally, experimental validation is carried out on the prototype of the proposed piezoelectric transducer and compared with the calculation results using the developed transfer matrix model. Experimental results matched well with the calculation results, which confirmed the correctness of the transducer designand verified the feasibility of the developed transfer matrix model. The proposed piezoelectric transducer presents the potential application for linear ultrasonic motors.

Simple Gain-Scheduled Control System for Dissolved Oxygen Control in Bioreactors

An adaptive control system for the set-point control and disturbance rejection of biotechnological-process parameters is presented. The gain scheduling of PID (PI) controller parameters is based on only controller input/output signals and does not require additional measurement of process variables for controller-parameter adaptation. Realization of the proposed system does not depend on the instrumentation-level of the bioreactor and is, therefore, attractive for practical application. A simple gain-scheduling algorithm is developed, using tendency models of the controlled process. Dissolved oxygen concentration was controlled using the developed control system. The biotechnological process was simulated in fed-batch operating mode, under extreme operating conditions (the oxygen uptake-rate’s rapidly and widely varying, feeding and aeration rate disturbances). In the simulation experiments, the gain-scheduled controller demonstrated robust behavior and outperformed the compared conventional PI controller with fixed parameters.

طراحی وشبیه سازی یک مبدل تمام پل شیفت-فاز بهبود یافته با مقدار RMS جریان و تنش ولتاژ کمتر

In this paper, an improved phase-shifted full-bridge (PSFB) dc-dc converter with coupled inductors and a current doubler rectifier (CDR) for battery charger applications in electric vehicles (EVs) is proposed. By using two coupled inductors as opposed to traditional output filter inductors, the RMS currents, the circulating current, and the voltage stresses on the secondary side are decreased. Besides, the zero-voltage-switching (ZVS) operation range is lengthened. Therefore, higher efficiencies are achieved. The two recursive inductors in the primary side have small and negligible values compared to the output inductors and, consequently, neither complex control systems nor extra components (like auxiliary circuits and active clamps) are needed. Thus, by using the proposed topology a simple structure with a simple control system will be obtained. Utilizing the proposed converter leads to reduce the RMS currents, the circulating current, and the voltage stresses on the secondary side. Besides, the cost and size of the system are not changed compared to the traditional one, as well. Moreover, the required energy for ZVS operation of power MOSFETs will be decreased which leads to higher efficiencies over a more extended operation range. Finally, the proposed and traditional converters have been simulated under the following conditions: the input voltage (150-250 V), switching frequency (200 kHz), the output voltage (75-85 V), and the output current (1.85-18.5 A). The simulation results validate the major benefits of the proposed phase-shifted full-bridge dc-dc converter over the traditional one.

Achieving natural behavior in a robot using neurally inspired hierarchical perceptual control

SummaryTerrestrial locomotion presents tremendous computational challenges on account of the enormous degrees of freedom in legged animals, and complex, unpredictable properties of natural environments, including the body and its effectors, yet the nervous system can achieve locomotion with ease. Here we introduce a quadrupedal robot that is capable of posture control and goal-directed locomotion across uneven terrain. The control architecture is a hierarchical network of simple negative feedback control systems inspired by the organization of the vertebrate nervous system. This robot is capable of robust posture control and locomotion in novel environments with unpredictable disturbances. Unlike current robots, our robot does not use internal inverse and forward models, nor does it require any training in order to perform successfully in novel environments.

Research on automatic test case generation method of flight control system based on UML state diagram

In order to realize the automatic test of flight control system, the automatic generation method of flight control system test case is studied by using UML state diagram. Using UML extension mechanism, the real-time extension scheme of UML state diagram of flight control system is given. Aiming at the real-time performance of flight control system, the migration equivalence class is constructed by using the time domain equivalence partition method. After the test path is generated according to the corresponding test standard, the test case is generated automatically. Taking a simplified flight control system as an example, the feasibility and practicability of the method are verified by comparing the time of generating test cases with that of generating test cases manually.

Hybrid Laminar Flow Control on A320 Fin: Retrofit Design and Sample Results

A flight test with a simplified hybrid laminar flow control (HLFC) system on the vertical tail plane (VTP) of an A320 aircraft was performed in April/May 2018. This HLFC system was a prototype for a simplified system that might be attractive for drag reduction of commercial long-range aircraft. The paper presents the design principles of a simplified HLFC system, including passive suction, and shows their application to aerodynamic and suction system design for the retrofit of an A320 VTP. Furthermore, sample flight test results will be presented and discussed.

Design and Analysis of a High-Gain Step-Up/Down Modular DC–DC Converter with Continuous Input Current and Decreased Voltage Stress on Power Switches and Switched-Capacitors

Due to concerns, such as global warming and depletion of fossil fuels, countries are forced to integrate energy storage devices (ESSs) and renewable energy sources (RESs), such as photovoltaic (PV) systems, wind turbines and fuel cells, into their power networks. Here, a new high gain DC–DC converter with step-up/down ability is proposed for modern applications. Since this converter provides high variable voltage gain, it can be employed for output voltage regulation purposes in RESs such as solar panels. Additionally, this converter provides a remarkable reduction in voltage stress on the switched capacitors and power switches. Due to its modular structure obtained by employing switched-capacitors (SCs), it is possible for this topology to gain a very high voltage conversion ratio using low duty-cycles produced by a simple and straightforward control system. To be specific, the more the number of SC cells increase, the more the output voltage increases. The proposed converter has a continuous input current allowing to extract the maximum power from RESs like PV panels. It should be noted that the application of this converter is not limited to the aforementioned ones since it can be used in various applications needing high voltage gains such as generating the desired voltage level in high voltage direct current (HVDC) systems especially their transmission lines. For validating the performance of the proposed structure, comprehensive comparisons and experimental results are presented.

New Dual-Input Zero-Voltage Switching DC–DC Boost Converter for Low-Power Clean Energy Applications

This article introduces a new dual-input nonisolated zero-voltage switching (ZVS) dc–dc boost converter. The proposed converter hybridizes two bidirectional and unidirectional boost converters to harvest energy from a rechargeable energy storage element and a clean energy dc generator, respectively. Hence, the proposed circuit utilizes three power switches, one power diode, two inductors, and an output filtering capacitor. The ZVS of all the power switches and zero-current switching (ZCS) for the power diode are realized without any auxiliary circuit. The soft-switching performance is designed to be valid for the whole power ranges of the converter input sources and the output load. The converter power switches are switched in pulsewidth modulation manner with two individual duty ratios, allowing to regulate the converter output voltage and control the extracted power from the input unidirectional port through a simple and useful control system. Depending on the converter duty ratios, its basic operation principle is analyzed in two different operation cases. The proposed converter benefits from a simple and compact structure, minimum numbers of power switches and magnetic elements, and high efficiency. The behavior of the proposed converter is analytically investigated, and a low-power laboratory prototype is designed and fabricated to evaluate the converter performance in different operating conditions.

An Arduino-based Low-Cost Hardware for Temperature Control

This paper describes a simple digital temperature control system where the popular LM35DZ sensor is used to sense the temperature of a resistive heating element and to provide a feedback to an Arduino microcontroller board. By subtracting the measured temperature from the desired temperature, a value of error is then processed by a conventional PID controller which provides an adjustment signal and drives a bipolar junction transistor in order to minimize or remove that error by a simple ON/OFF switching of the power to the heating element. The control is also done using logic controllers such as ON/OFF and hysteresis controllers. The evaluation of each controller performance is based on rise time, overshoot, steady state error and the most common performance criterion which is the integral of the absolute value of the error. Besides that, the arduino integrated development environment (IDE) software is used to write the program code. Moreover, other languages are used to program the Arduino such as Matlab support package for Arduino hardware, Flowcode IDE and mBlock.