On-off Control Method Research Articles

Design of Automation and Monitoring Systems for Filling Mineral Water Tanks Based on Android Applications

The PURE “ARH” refillable drinking water filling station located on Arief Rahman Hakim Street, Klampis Ngasem, is still not very practical and efficient. This is because the machine is still manual, operated by pressing a manual button to switch it on and off, and requires visual observation until the water container is filled. As a result, this creates uncertainty in the volume of water being filled. Therefore, in this research, an automated prototype and monitoring system for filling mineral water tanks based on an Android application were developed. The use of an HCSR04 ultrasonic sensor for mineral water tank detection at approximately 20 cm and an FS400A water flow sensor to determine the volume of water filled is employed. Subsequently, the results of mineral water tank’s water filling can be monitored, displaying the number of fillings and the volume of water filled, which are then sent to the Android application. Three mineral water tank sizes are used as samples: 5 liters, 15 liters, and 19 liters. The filling process allows configuration of the filling volume through the Android application, allowing refillable drinking water station owners to set their desired set points based on the mineral water tank’s capacity. The validation results of the FS400A G1 flow sensor shows an average error of 1.35%, resulting in an accuracy level of 98.65%, while the HC-SR04 ultrasonic sensor has an average error of 1.31% with an accuracy level of 98.69%. As for the testing of the filling mineral water tanks control system using the on-off control method, in this research, it has been successfully achieved with an error rate of 0.9% for a 5-liter set point, 1.3% for a 15-liter set point, and 2.4% for a 19-liter set point. From these results, it can be concluded that the water-filling control system operates effectively, as the actuator functions properly with a logic state of one (1), and once the set point is reached, the actuator turns off with a logic state of null (0).

Valve control system on a venturi to control FiO2 a portable ventilator with fuzzy logic method based on microcontroller

<p>The results of several studies for portable ventilators state that it is difficult to<br />regulate oxygen levels of fraction of inspired oxygen (FiO2) that are in<br />accordance with what is needed directly during the implementation of oxygen<br />therapy. Some portable ventilators cannot set the FiO2, so the ventilators work<br />with a fixed FiO2. To overcome this problem, medical oxygen with a level of<br />100% is lowered by mixing with free air with an oxygen content of about 40%.<br />Mixing is carried out using a venturi with a large/wide hole that can be<br />adjusted using a slated disk rotated by a direct current motor. The rotation<br />control method uses Mamdani's fuzzy logic. The results of clinically lab-scale<br />testing show that the fuzzy logic control system is able to control the average<br />error pressure of 10.3%, better when compared to the on-off control method,<br />which is 14.5%. The fuzzy logic method is able to increase the accuracy of<br />FiO2 on a portable ventilator.</p>

Vibration isolation characteristics of magnetorheological damper for the large wind turbine gearbox

ABSTRACT The gearbox vibration isolation theory in the large wind turbine transmission system is analyzed. The host frame is flexible, and the vibration isolation system is approximately equivalent to a two-degree-of-freedom system. According to large wind turbine gearbox isolation requirement, and a vibration isolation device of magnetorheological damper of the large wind turbine gearbox is designed, the magnetic field characteristics inside the magnetorheological damper are simulated and calculated by using COMSOL, when 0.5, 1, 1.5and 2 A currents are passed through the magnetorheological damper coil, the magnetic induction intensity of the damping gap and the output force of the magnetorheological damper are calculated, it can reach 1300N-5400N, which meets the gearbox vibration isolation requirements. It designed the on-off current control method of the magnetorheological damper. The prototype is tested on a certain type of offshore wind turbine, and the acceleration spectrum signals of the gearbox in the Z direction are collected under the working conditions of 990, 1200 and 2000 r/min. According to the collected data values, the vibration isolation characteristics of the designed magnetorheological damper are analyzed; the data show that the vibration level drop is about 20 dB, and the vibration isolation effect is good. By using the coherence coefficient method to process the measured data, the modified transfer function is obtained, which is consistent with the theoretical transfer function of the vibration model of two-degree-of-freedom system, so it is proved to be reasonable. The vibration isolation characteristics of rubber and the magnetorheological damper are compared at the rated speed, and it shows that the maximum vibration acceleration of the gearbox under the magnetorheological damper reduces from 0.375 m/s2 to 0.175 m/s2, which verify the damping effect of the magnetorheological damper.

Secrecy performance analysis of IRS-NOMA systems

In this paper, we propose to utilize an intelligent reflecting surface (IRS) as a promising technology to enhance the coverage and physical layer security of non-orthogonal multiple access (NOMA) system. In particular, an IRS-assisted NOMA system is considered with the aid of careful channel ordering of the NOMA users, in which the transmitter sends superposed signals to multiple legitimate users by virtue of the IRS in the presence of multiple eavesdroppers. Meanwhile, the secrecy performance of the IRS-assisted NOMA system is investigated under two wiretapping cases: non-colluding and colluding external eavesdroppers. In the non-colluding case, eavesdroppers operate independently, while in the colluding case, every eavesdroppers can combine their observations to decode the messages. To this end, we derive the approximate closed-form expressions for the secrecy outage probability (SOP) and the asymptotic SOP for each wiretapping case. Also, we assume that the phase of the IRS elements is set by using the ON–OFF control method. Based on analytical results, we show that the secrecy diversity order of the IRS-NOMA at legitimate users is in connection with the number of reflecting elements. From the numerical results, it can be seen that the IRS-NOMA can achieve superior secrecy performance with increasing the number of reflecting elements of the IRS. However, we also find out that using the finite ON state reflective elements can improve the secrecy performance. Actually, increasing the number of ON state reflective elements above five has a negative effect on the system’s secrecy performance.

A frequency-dependent variable damping control method for base-isolated structures under ground motions with different frequency characteristics

The base isolation technique is commonly adopted to protect important structures from earthquake damages. Typically, a high damping ratio for the base isolation layer is useful in reducing the structure's resonance effect under low-frequency (long-period) ground motions, and a low damping ratio is preferred in minimizing the acceleration response under high-frequency (short-period) ground motions while not causing significant displacement response. To realize optimal control for base-isolated structures under ground motions with different frequency characteristics, the semi-active control is adopted and a frequency-dependent variable damping (FVD) control method based on a transmissibility weighted fast Fourier transform (TWFFT) spectrum is newly proposed. The FVD control method considers the influences of different frequency components of ground motions on base-isolated structures by developing the TWFFT spectrum of the detected ground accelerations. A series of shaking table tests for a base-isolated steel frame structure with semi-active control were carried out to evaluate the effectiveness of the FVD control method. The test results demonstrated that the FVD control method could realize optimal control of the structure under various types of ground motions, and it was more effective than the ON-OFF control method which only considered the dominant frequency characteristics of the ground motions.

Experimental Analysis of Control Methods in Solar Water Heating Systems

This paper focuses on an analysis of selected control methods in solar heating systems. Proportional, ON-OFF, and new proposed IPC control methods were tested. Experimental tests were conducted under natural conditions using the author’s method of clustering measurement days. In the form of thermal energy gains in the storage tanks, the results for all tested control methods are presented. The ON-OFF control method is suitable for low variability of solar radiation conditions but is ineffective under dynamic solar radiation conditions. The proportional controllers collect thermal energy under high variability solar radiation effectively, but they tend to cause thermal drifts from the system under high heat load. The proposed IPC control method prevents the waste of heat energy and makes more efficient use of the high and dynamic solar radiation. In conclusion, energy gains depend more on the level of solar radiation and less on its variability. However, the variability of solar radiation makes control in solar systems more challenging, and it is one of the factors that should determine the control strategy. The novelty of this work is based on an extension of the control algorithm by adding the temperature at the entry and exit of the solar coil. This makes it possible to eliminate thermal drift and observe the intensity of heat transfer to the water in the tank.

직수정수기의 순간온수 온도제어에 관한 연구

The instant hot water function of the tankless water purifier requires stable temperature control technique because water is passed the hot water module to which power is applied, and the water is instantaneously heated and supplied directly to the user. In this paper, we propose a method to optimize the preheating time by inserting a temperature sensor inside the hot water module to accurately check the current heating state of the hot water module and calculate the amount of heat required for heating to the target temperature. In addition, we propose a duty pattern of the triac on-off control method that makes it easy to calculate the amount of heat even when the control environment changes. The proposed technique is verified stable temperature heating effect through reducing the supplied time to user and deviation of hot water temperature of experiments for outlet temperature measurement using a tankless water purifier.

SHAKING TABLE TESTING ON A SCALED SEMI-ACTIVE CONTROLLED THREE-DIMENSIONAL FLOOR ISOLATION SYSTEM

In order to reduce the influence of vibrations caused by large shaking table testing to machine tools and precision instruments, etc. in shaking table laboratory and surrounding structures and improve the comfort of the people inside the structures, a frequency dependent and semi-active controlled three-dimensional (3D) floor isolation system was established. An on-off control method was proposed based on the dominant frequency of the input acceleration obtained by an online frequency detection method. Shaking table tests were conducted with vibrations caused by sinusoidal and earthquake type shakings. The test results show that the online frequency detection method can quickly and effectively detect the dominant frequency of the input motion, and the semi-active control can effectively reduce the floor vibrations with the detected frequency information. To improve the control efficiency in practice, the damping of the MR damper in the low damping force mode should be controlled as low as possible.

Height stability control of a large sprayer body based on air suspension using the sliding mode approach

When a high clearance self-propelled sprayer sprays, the sprung mass varies with the amount of liquid in the tank, which causes a change in the height of the sprayer body. This change not only is harmful to the sprayer ride comfort, but also has a greater impact on the sprayer application quality. In this paper, a large-scale high clearance self-propelled sprayer with air suspension was taken as the research object. Based on vehicle dynamics and air thermodynamics theory, a mathematical model of air spring inflation/deflation was established, then a 3 degree of freedom (3-dof) vertical dynamics model of sprayer air suspension was built. On this basis, the height control strategy of the sprayer body was formulated. Due to the nonlinear characteristics of air suspension, two control algorithms, namely sliding mode control and the on-off control, were used to design the suspension height stability controller, respectively. A simulation experiment was carried out by using the sprayer spraying crops as an example. The simulation experiment results showed that sliding mode control and on-off control could track and stabilize the height of the sprayer body when it changed under no excitation and D-grade road random excitation. However, due to strong nonlinearity and hysteresis of the pneumatic system, on-off control precision was poor. With the on-off control method, further reduction of the sprung mass would change the internal parameters of the pneumatic system, cause the air spring over deflation, even worse, the over deflation phenomenon presented a serious trend and cause system instability under random road excitation. Compared with on-off control method, sliding mode control approach had good control ability and precision due to its robustness to change in model parameters. The research will provide a reference for the height stability adjustment of large high clearance self-propelled sprayers during spraying and dosing operations.

An efficient ripple-free LED driver with zero-voltage switching for street lighting applications

ABSTRACTAn efficient ripple-free light-emitting diode (LED) driver circuit is proposed with zero-voltage switching (ZVS) and dimming control. The proposed driver circuit utilizes a full-bridge configuration. The LED lamp current is the sum of two inductor currents which are out of phase. This makes the LED lamp current ripple free. Larger portion of lamp power is supplied by the dc voltage source connected in series with LED lamp. Small amount of power is processed by bridge circuit. Devices of the bridge circuit conduct only ripple current of the load inductor and a small current of an inductor which helps in ZVS. Hence, both conduction and switching losses are reduced. In addition, LED lamp current can be regulated at required operating current. The dimming feature is attained by on-off control method. This proposed configuration also helps in reducing components count. An experimental prototype of 87 W has been developed and tested at full load and different dimming levels. Experimental results validate simulation results.

Micro-mirror with hybrid photoelectric-electrostatic driving of PLZT ceramic

A novel micro-mirror driven by hybrid photoelectric-electrostatic actuation of PLZT ceramic is proposed based on the anomalous photovoltaic effect of PLZT ceramic. On the basis of analysis of coupling relationships of multi-physics fields of PLZT ceramic, the photovoltage of PLZT ceramic is established during illumination and light off phases. Furthermore, the relationship between the driving displacement and the photovoltage of PLZT ceramics is present. In addition, the feasibility of micro-mirror with hybrid photoelectric-electrostatic driving is verified via closed-loop control for photovoltage of PLZT ceramic. The experimental results show that the photovoltage of PLZT ceramics has good dynamic control precision using on-off closed-loop control method.

PLZT Ceramic Driving Rotary Micro-mirror Based on Photoelectric-electrostatic Mechanism

Based on the anomalous photovoltaic effect of PLZT, a rotary micro-mirror driven by hybrid photoelectric-electrostatic actuation of PLZT ceramic is proposed. Firstly, the mathematical modelling of coupled multi-physics fields of PLZT ceramic is established during illumination and light off phases. Then, the relationship between the rotation angle and the photovoltage of PLZT ceramics is established. In addition, the feasibility of rotary micro-mirror with hybrid photoelectric-electrostatic driving is verified via closed-loop control for photo-induced voltage of PLZT ceramic. The experimental results show that the photo-induced voltage of PLZT ceramics has good dynamic control precision using on-off closed-loop control method.

Interference Management in Ultra-Dense Networks: Challenges and Approaches

Capable of enhancing spatial multiplexing and greatly expanding network capacity, network densification has undoubtedly become a general trend in future wireless networks. However, in addition to the expected advantages, the overuse of spatial resources would result in unpredictable and overwhelming interference as well due to the limited spectrum resources and highly disorganized network infrastructures. Hence, a critical issue arises: are conventional IM techniques still applicable and effective to tackle the interference in UDN? To shed light on the problem, in this article we first investigate the characteristics of interference in UDN and then provide an overview of the existing dominant IM techniques. It is found that, due to the complicated interference, most IM techniques designed for sparse networks would lose their merits when applied in UDN. To reap their potential benefits, we design an IM entity for UDN, aided by which an adaptive on-off power control method is proposed. Results reveal that network capacity could be significantly improved using the proposed method, especially in UDN. In addition, open issues and challenges for IM co-design with stateof- the-art communications technologies are highlighted to provide insight on the potential direction in future wireless networks.

Online control of critical speed vibrations of a single-span rotor by a rotor dynamic vibration absorber at different installation positions

The serious vibration of rotors around the critical speed is a problem in rotor systems. To overcome this problem, a single-span twodisk rotor bench was built to simulate the starting process of a rotor. A new Rotor dynamic vibration absorber (RDVA) was designed and installed in the middle of the rotor. A on-off control method based on speed was applied to control the on-off position of the electromagnet in RDVA. Therefore, the natural frequencies between two selected values could be changed. The principles for the vibration control of the rotor system were studied. The vibration suppression performance of an RDVA is a function of its location. The location of the RDVA is subject to several constraints due to the compact structure of the rotor system. As a result, RDVA cannot always be installed at the optimal location of vibration suppression. Accordingly, a study was performed to observe the effect of RDVA location on the vibration suppression performance. Results showed that installing RDVA with on-off control between the two disks not only suppressed the violent vibrations of the rotor at critical speed during the starting process but also avoided the two resonance peaks generated by the traditional absorber. RDVA maintained the vibration of the rotor at a low level in the entire speed range. Furthermore, the vibrations of the rotor system decreased by 20 % when RDVA was installed near the rotor support.

Closed-loop control for deflection of cantilever beam based on hybrid photovoltaic/piezoelectric actuation mechanism

This paper proposes a novel non-contact closed-loop control model for the deflection of cantilever beam based on hybrid photovoltaic/piezoelectric actuation mechanism. The polyvinylidene fluoride (PVDF) piezoelectric actuator was driven under the photovoltage of lead lanthanum zirconate (PLZT) cera mic which was irradiated by ultraviolet light. The closed-loop control equations for the deflection of cantilever beam were derived based on the coupled multi-physics model of PLZT ceramic and the constitutive model of cantilever beam. According to the identified parameters obtained from the static experiments during illumination phase and light-off phase, the mathematical simulation for closed-loop control of the deflection of cantilever beam was conducted. Furthermore, the corresponding experiments based on the hybrid photovoltaic/piezoelectric actuation mechanism were carried out to verify the proposed control model. The simulation and experimental results show that the deflection of cantilever beam laminated with a PVDF actuator can successfully achieve the target value by applying the UV light to the PLZT ceramic using a simple on-off control method.

大规模MIMO-D2D蜂窝网络中的下行传输速率研究

为了顺应第五代移动通信技术(5G)的发展，本文探讨了大规模MIMO与D2D通信混合蜂窝网络中的下行链路频谱效率问题。特别，针对三种用户分布场景，利用D2D用户和蜂窝用户覆盖率解析表达式分析了蜂窝用户传输速率变化情况。结果表明，为确保蜂窝通信，应严格控制D2D用户接入数目，同时增加天线数，以有效弥补干扰。此外，通过对D2D用户引入On-Off功率控制方法，并优化接入传输概率，本文实现了对D2D用户的频谱效率的提升。 In order to adapt to the development of the fifth generation mobile communication technology (5G), this paper investigates the downlink transmission rate for D2D underlaying large-scale MIMO cellular networks. In particular, based on analytical expressions of coverage probabilities of both D2D users and downlink cellular users, the transmission rate of cellular users are analyzed for three user distributed scenarios. The results show that in order to ensure the cellular communication, the number of D2D users should be strictly controlled, and the number of antennas can be increased in order to compensate for the interference efficiently. The transmission rate with the D2D users can be improved by making use of On-Off power control method for D2D users and optimizing the access transmission probability.

Modeling and control of an integrated electric parking brake system

The estimation of the frictional and clamping forces is one of the key issues in an integrated electric parking brake control system design and implementation. In this paper, we present a modeling and control system design for the integrated electric parking brake system (IEPBs). Based on the state-dependent switched IEPBs models, the whole working principles can be analyzed mathematically. Based on the mathematical models, clamping force, rotor angle position and motor current are set as the feedbacks respectively to compare the control performance. The simulation results show that with a force sensor, the clamping force can be controlled well, while the cost is increased seriously; and for the angle position feedback, the conventionally used position–force characteristic curve may change due to the external temperature and aging problem, which may result in an insufficient clamping force; the current control feedback strategy outperforms the other two strategies in terms of cost, implementation as well as the robustness with respect to the external disturbances. Finally, the proposed IEPBs model with current feedback control loop is verified through the experimental results with an on-off control method.

On-off closed-loop control of vagus nerve stimulation for the adaptation of heart rate.

Vagus nerve stimulation (VNS) is a potential therapeutic approach in a number of clinical applications. Although VNS is commonly delivered in an open-loop approach, it is now recognized that closed-loop approaches may be necessary to optimize the therapy and minimize side effects of neuro-stimulation devices. In this paper, we describe a prototype system for real-time control of the instantaneous heart rate, working synchronously with the heart period. As a first step, an on-off control method has been integrated. The system is evaluated on one sheep with induced heart failure, showing the interest of the proposed approach.

A novel hybrid steady-state model based controller for simultaneous indoor air temperature and humidity control

Due to the strong coupling between two control loops, it is always a challenge to develop appropriate control algorithm for simultaneously controlling indoor air temperature and humidity using a direct expansion (DX) air conditioning (A/C) system, making it an engineering application where no expert experience is available. Although the control performance of a steady state model based controller (SSMBC) was normally regarded to be not comparable to that of a dynamic model based controller, the successful development of a SSMBC may provide new insights of the control mechanism. In this paper, a SSMBC was developed based on a previous developed steady state model of a DX A/C system. Its control performance was theoretically analyzed and experimentally tested. It was proven that by utilizing a specific activating method, the SSMBC could achieve much better control performance than that of a traditional On-Off control method. However, the SSMBC could be further improved. Based on the theoretical analysis of the interaction between the changes of system operating states and those of indoor air thermal states, a hybrid SSMBC, which consisted of a SSMBC and a stabilizing controller, was further developed. The accuracy and sensitivity of the novel hybrid SSMBC are experimentally validated.

Semi-active Control of Building Structures using Variable Stiffness Device and Fuzzy Logic

Semi-active control devices, also called “Intelligent” control devices, constitute the positive aspects of both the passive and active control devices. A semi-active control strategy is similar to the active control strategy, but this control device has been shown to be more energy-efficient than active devices. A particular type of semi-active control device, the Variable Stiffness Device (VSD), consists of a hydraulic cylinder with a normally closed solenoid control valve inserted in the tube connecting the two cylinder chambers. This paper emphasizes on the application of Semi-active Fuzzy Logic Controller (SFLC) of this system for getting the best results in the reduction of the building responses under earthquake excitations. For the numerical example, a 12-story building, located in the city of Rasht, Iran, is modeled as 3-D frame and the problem is solved in state space. The results obtained from the proposed control scheme (SFLC) are compared with those obtained from the ON-OFF control method. It is found that the SFLC is highly effective in reducing the responses of the example building than the ON-OFF algorithm. In this study, the optimal values of the fuzzy rule bases, membership functions, and the location of the control device are determined.