This paper proposes a FPGA-based Sliding Mode Controller for scaled bilateral teleoperation. The control algorithm is derived by using the sliding mode control based design approach. The applied design procedure replaces a discontinuous control with a continuous one. Thus, it guarantees chattering-free performance whilst retaining practical robustness regarding disturbances, and provides easy model-free implementation. A high control rateis strongly required in order to achieve high-performance scaled bilateral teleoperation. Hence, the control algorithm is implemented by the FPGA. In order to design a sufficient logic circuit for the FPGA, general optimization approaches are presented that aim to minimize hardware resources, and to optimize the control rate. The design applies high-level programming language (LabVIEW) for rapid prototyping. The presented algorithms were validated by the 2- DoF laboratory bilateral teleoperation system.
COBISS.SI-ID: 16563990
This paper proposes the field-programmable gate array (FPGA) implementation ofa variable structure system predictive sequential switching control strategy, as applied to a permanent magnet synchronous machine. In the case ofac motor drives, in contrast to conventional vector control where the inverter is not taken into consideration by the controller, the proposed control integrates the inverter model and the inverter states. It allows obtaining faster torque dynamics than vector control algorithms. The main design specifications are a reduced switching frequency and simple hardware implementation. A predictive sliding mode controller has been developed, designed as finite-state machine, and implemented with a FPGA. This new logic FPGA torque and speed controller has been developed, analyzed, and experimentally verified.
COBISS.SI-ID: 16609302
This paper describes a complete digitally controlled dc-dc buck converter performed by field-programmable gate array (FPGA) circuitry. The voltage and current-mode control is based on a voltage control oscillator (VCO) performed measurements regarding output-voltage and inductor current, respectively. This measurement principle also uses digital-counters (digital-integrators) in order to obtain integral values for the output-voltage and inductor current. In analog current-mode control, the instantaneous inductor current-value-measurement is used for the switching action. When the VCO is used for the inductor current measurement, the integral is measured during the switching-on time set as an observation interval and the switching action occurs based on this measurement. Such a principle enables full digitalization of the voltage- and current-control loop and also the used measurement principle is capable of rejecting the switching disturbances during current and voltage measurements. All the tasks for current and voltage control were implemented within the FPGA. The algorithm was verified by simulation and experimentation at a switching-frequency of 25kHz.
COBISS.SI-ID: 17671446
This paper presents a current sensing principle appropriate for use in power electronics’ converters. This current measurement principle has been developed for metal oxide semiconductor field effect transistor (MOS-FET) and is based on UDS voltage measurement. In practice, shunt resistors and Hall effect sensors are usually used for these purposes, but the presented principle has many advantages. There is no need for additional circuit elements within high current paths, causing parasitic inductances and increased production complexity. The temperature dependence of MOS-FETs conductive resistance RDS-ON is considered in order to achieve the appropriate measurement accuracy. The “MOS-FET sensor” is also accompanied by a signal acquisition electronics circuit with an appropriate frequency bandwidth. The obtained analogue signal is therefore interposed to an A-D converter for further data acquisition. In order to achieve sufficient accuracy, a temperature compensation and appropriate approximation is used (RDS-ON = RDS-ON(Vj)). The MOS-FET sensor is calibrated according to a reference sensor based on the Hall-effect principle. The program algorithm is executed on 32-bit ARM M4 MCU, STM32F407.
COBISS.SI-ID: 18853910
The paper investigates a control approach for achieving reliable zero-voltage switching transitions within the entire operating range of a conventional nonisolated bidirectional dc-dc converter that utilizes synchronous rectification. The approach is based on operation in the discontinuous conduction mode with a constant reversed current of sufficient amplitude, which is achieved by load-dependent variation of the switching frequency. This paper focuses on the obtained resonant voltage transitions and provides analytical models for determining the reversed current and timing parameters that would ensure safe, reliable, and highly efficient operation of the converter. In addition, the proposed approach solves the synchronous transistor's spurious turn-on and body diode reverse recovery induced issues, does not require any additional components or circuitry for its realization, and can be entirely implemented within a digital signal controller. The effectiveness and performance of the presented control approach was confirmed in a 1-kW experimental bidirectional dc-dc converter that achieved 97% efficiency over a wide range of output powers at switching frequencies above 100 kHz.
COBISS.SI-ID: 18799382
A mechatronic system consists of a mechanical system and electric actuators. The presented event-driven control of a mechatronic system has been implemented on a field-programmable gate array (FPGA) platform. The supervisor provides robust, safe, and transparent control, where the finite-state machine (FSM) defines all the possible directions for implementation. In order to make the supervisor more transparent, the FSM has been divided into three main parts, each signified by a main color (green, yellow, and red - semaphores). These colors indicate the condition of the system. The supervisor has been upgraded with a graphical user interface with indicators that directly show the state of the FSM. The interface includes additional logical I/O signals, in order to make the system more useful. The supervisor is executed parallel to the basic motor control on the FPGA. This paper introduces a robust current controller of a brushless ac (BLAC) motor, upgraded with a proportional-integral velocity controller. The application of the proposed event-condition-action-based method is illustrated using the example of the FSM motion control of a BLAC motor with integrated I/O signals.
COBISS.SI-ID: 18379286
This paper presents a miniature, all-optical, thermal conductivity fiber-optic sensor, which can be applied to various fluid composition identification situations. The sensor is composed of a short section of highly absorbing fiber, which is configured as a Fabry-Perot interferometer. A higher power laser diode is used to heat the absorbing fiber periodically, while proper signal integration system issued in order to observe temperature variations of the heated fiber. These variations are further correlated to the surrounding fluid’s thermal conductivity. The sensor was applied experimentally to various fluid identification situations, including gas/liquid and liquid–liquid phase detection, identification of different fluids (including liquids and gases), liquids’ binary mixtures mass ratio determination, and some common fluid identification applications.
COBISS.SI-ID: 20017174
Magnetic levitation systems have become very important in many applications. Due to their instability and high nonlinearity, such systems pose a challenge to many researchers attempting to design highperformance and robust tracking control. This paper proposes an improved adaptive fuzzy backstepping control for systems with uncertain input nonlinear function (uncertain parameters and structure), and applies it to a magnetic levitation system, which is a typical representative of such systems. An adaptive fuzzy system is used to approximate unknown, partially known or uncertain input nonlinear functions of a magnetic levitation system. An adaptation law is obtained based on Ljapunov analysis in order to guarantee closed-loop stability and good tracking performance. Initial adaptive and control parameters have been initialized with Symbiotic Organism Search optimization algorithm, due to strong non-linearity and instability of the magnetic levitation system. The theoretical background of the proposed control method is verified with a simulation study and implementation on a laboratory experimental application.
COBISS.SI-ID: 20349462
Temporal trends in source normalized impact per paper (SNIP) values for the three top-ranking nursing journals were analyzed and compared to explore whether predicting future SNIP values based on trend analysis could be an innovative service provided by librarians. The International Journal of Nursing Studies, Journal of Nursing Scholarship, and Journal of Advanced Nursing were the three top-ranked nursing journals according to 2015 SNIP values. SNIP values for the selected journals were retrieved from the Scopus database, and extracted data were exported to Joinpoint trend analysis software to perform trend analysis.Predictions of journal metrics based on statistical joinpoint regression may not be completely accurate. Using this technique, however, a librarian can reasonably claim which journal will retain or even improve its prestige in the future and thus safely advise prospective authors on where to publish their research.
COBISS.SI-ID: 20847382
This study proposes a new control method for a pulse-density modulated microinverter and its implementation within a field programmable gate array circuit. The structure and operating principle of the studied microinverter demand implementation of a pulse-density modulation-based control method with two independent control loops. The first one ensures a constant input current from the source while the second one provides a sinusoidal voltage at the converter's output. At the same time the implemented control method ensures zero-current switching of the utilised power transistors in decoupling and output stages which allows operation at high switching frequency. The performance of the proposed control method for a microinverter operating in island mode was experimentally verified in steady-state operation, as well as during load transients.
COBISS.SI-ID: 19750678