Methods of Ensuring Invariance with Respect to External Disturbances: Overview and New Advances

In this paper, we carry out a demonstration and comparative analysis of known methods of the synthesis of various control laws ensuring the invariance of the output (controlled) variable with respect to external disturbances under various assumptions about their type and channels of acting on the control plant. Methods of the synthesis are presented on the example of a third-order nonlinear system with single input and single output (SISO-systems), dynamic feedback synthesis is presented at a descriptive level and the focus is on procedures of static feedback synthesis. For the systems in which the matching conditions are not satisfied, it is concluded that it is expedient to introduce smooth and bounded nonlinear local feedbacks. Within the framework of the block control principle, we developed an iterative procedure of synthesis of S-shaped sigmoid feedbacks for such systems. Nonlinear local feedbacks ensure stabilization of the output variable with the given accuracy and settling time as in a system with traditionally used linear local feedbacks with high gains. However, in contrast to it, sigmoid functions do not lead to a large overshoot of state variables and control actions.

Fuzzy Model of Situational Control of the Flight Parameters of an Autonomous Unmanned Aircraft under Uncertainty Conditions

The article outlines the main problems of automatic planning of the behavior of an autonomous unmanned aerial vehicle in unstable air conditions. It is shown that the urgency of the problem is due to the fact that an autonomous unmanned aerial vehicle independently forms and implements its flight route without support from a ground control station. There is therefore a need to develop a method for automatic control of programmed movements associated with the implementation of the route constructed by the problem solver. To solve this problem we propose an approach to regulating the parameters of the state of dynamic objects based on the principle of situational control of the goal-directed behavior of complex systems in changing environmental conditions. The expediency of choosing this control principle is due to the fact that the state of an autonomous unmanned aerial vehicle during its flight is characterized by a large number of parameters and disturbing environmental factors. In order to effectively implement this control principle, we introduce the concept of a complete problematic situation, which consists of deviations of the state parameters of an autonomous unmanned aerial vehicle from the required values during flight and disturbing environmental factors. On this basis, a fuzzy model of situational control of the state parameters of an autonomous unmanned aerial vehicle functioning in an unstable environment is developed, in which linguistic variables and functions are used to provide a generalized presentation of reference problem situations, as well as to describe the deviations of the state parameters and disturbing environmental factors. The conditions are determined under which the reference indistinctly presented problem situations generalize the actual problem situations that arise at the control object. This makes it possible to significantly reduce the number of logical-transformational decision rules in the situational control model and to promptly automatically determine effective control actions in problematic situations that ensure the effective implementation of programmed movements of an autonomous unmanned aerial vehicle under conditions of uncertainty. In conclusion, it is shown that for the implementation of control actions which are selected on a situational basis with increased requirements for the accuracy of regulation of the time-varying parameters of the control object and a significant level of possible discrepancies between their actual and specified values in conditions of uncertainty, it is advisable to use indistinctly implemented proportional, integral and differential regulation laws.

Design of stepper motor driver based on STM32

In the field of industrial control, stepping has been widely used as an actuator. For this article, based on STM32F103 as the control core, the functions of start and stop, forward rotation, reverse rotation and speed regulation of the stepping motor are realized through four buttons. The system uses L293D to drive a stepper motor, LED0 and LED1 two status lights display the motor’s forward and reverse rotation status, and the digital tube displays the current stepper motor speed. The whole system includes L293D module, button module, status light module and speed display module. The whole system is modeled, theoretically analyzed and simulated based on the drive control principle of the stepper motor, and the precise and stable control performance of the system under different occasions is further verified through experiments.

Research on magnetic bead motion characteristics based on magnetic beads preset technology

In order to improve the detection efficiency and accuracy of microfluidic chip, a magnetic beads preset technology were designed by using double permanent magnets as external magnetic field and the motion characteristics of preset magnetic beads were studied. The control principle of magnetic beads preset technology was introduced in detail, and the control structure was designed. The coupled field characteristics for magnetic beads in microchannels were analyzed, and the motion models of magnetic beads were established based on the magnetic beads preset technology, including capture motion and mixing motion. The relationship between the magnetic field force and the flow velocity for capturing magnetic bead, and the mixing time under the influence of flow field and magnetic field were derived. The magnetic beads preset technology effect was verified by experiments and numerical simulations were developed to analyze the influence of aspect ratio of permanent magnet on magnetic field. The study showed that the accuracy and efficiency of the magnetic bead control in the microchannel could be better realized by the magnetic beads preset technology. The derivation of the magnetic bead motion model can understand the motion characteristics of the magnetic bead more clearly, facilitate accurate control of the magnetic bead, and improve the success rate of the microfluidic detection.

Solar Power Plant Storage System

The article analyzes changes in the legislation on the rules of electricity generation from renewable sources and the introduction of penalties for imbalances, which encourages producers to improve the forecast of electricity generation and modernization of existing power plants by installing energy storage systems. Possible connection points and charge/discharge device (CDD) converter topologies for an energy storage system are analyzed and the converter that meets technical requirements of the system are selected. As a result, the connection from the direct current side has a number of advantages: simpler CDD structure and control principle, in comparison with alternating current; no galvanic separation between input and output. Converter analysis showed, that due to a high operating voltage, usage of resonant topologies is undesirable and the absence of galvanic separation makes bridge converter usage impractical. Therefore, to solve this problem, a bidirectional converter without galvanic separation with hard switching is proposed. To reduce the level of dynamic and static losses, it is advisable to use a modular topology converter with alternating phases. The operating modes of such a converter at a given error of the weather forecast are analyzed. To improve quality of the generated electricity, it is expedient to use a power stabilization mode. Due to the higher values of charge/discharge currents, as well as higher energy density compared to acid-lead, a lithium-ion battery was chosen. According to the selected operation mode, its minimum capacity was calculated. When using a minimum battery capacity, due to the difference between the maximum discharge and charge current of the battery, a mode of partial power stabilization is possible. This mode is used only when the forecast error is more than 52% in the charging mode. A charge/discharge device were designed for a 50 kW SMA Sunny Tripower CORE1 inverter and 20*315W LP156*156-M-60 solar panels connected in series. The control principle for such CDD is described. Control algorithm can be divided into four stages: obtaining the predicted solar radiation power in the forecast interval; predicted illumination power conversion into electric power; predicted power calculation and the amount of energy that will be generated and transferred by the solar station to the regulator in the forecast interval; power setpoint stabilization on the forecast interval based on the proportional-integral (PI) control law. To verify the obtained theoretical relations, converter parameters with a typical input data were calculated. Model of the converter was created in the MATLAB® Simulink® environment and its operability was checked.

Research on Magnetic Bead Motion Characteristics based on Magnetic Beads Preset Technology

In order to improve the detection efficiency and accuracy of microfluidic chip, a magnetic beads preset technology were designed by using double permanent magnets as external magnetic field and the motion characteristics of preset magnetic beads were studied. The control principle of magnetic beads preset technology was introduced in detail, and the control structure was designed. The coupled field characteristics for magnetic beads in microchannels were analyzed, and the motion models of magnetic beads were established based on the bead preset technology, including capture motion and mixing motion. The relationship between the magnetic field force and the flow velocity for capturing magnetic bead, and the mixing time under the influence of flow field and magnetic field were derived. The magnetic beads capture effect of magnetic beads preset technology was verified by experiments. The study showed the magnetic beads preset technology can better realize the accuracy and efficiency of the magnetic bead control in the microchannel. The derivation of the magnetic bead motion model can understand the motion characteristics of the magnetic bead more clearly, facilitate accurate control of the magnetic bead, and improve the success rate of the microfluidic detection.

Restraining Situational Luck

This chapter examines circumstantial luck, or the luck of being in circumstances where a moral response or course of action is called for. The anti-anti-luckist programme is maintained for circumstantial luck as well as resultant luck. The argument proceeds, first, through an examination of Good Cases, calling for praiseworthiness. The fact that a well-intentioned agent is not in a position to collect praise for performing a meritorious act does not generate any serious moral concern. We can still praise this inactive agent for her dispositions if we wish to, and morality does not insist, in any case, upon equal opportunities for collecting praise. These lessons are then transferred to Bad Cases, calling for blameworthiness. The chapter also engages in detail with Michael Zimmerman’s argument involving situational luck, which combines circumstantial luck with constitutive luck. Zimmerman’s radical argument suggests that one agent should be no more blameworthy than another agent if they are separated only by luck, whether of the resultant, circumstantial, or constitutive variety. It is suggested here that Zimmerman’s argument misfires, due to an inconsistency between two principles he relies upon: the ‘Control Principle’ and the ‘No-Difference Claim’.

Comparative study of control techniques for three phase PWM rectifier

This paper studies and compare the performances of different control strategies of 3-phase active rectifier under different load and frequency conditions. There are three main control approaches to be investigated such as: Voltage Oriented Control (VOC), Direct Power Control (DPC) and Model Predictive Control (MPC). The traditional method VOC has been used widely in practice. Its control principle is available to many different grid-connected converter systems such as electric drive system, renewable energy conversion system. However, the problem of optimal design of the current regulators for the different operating conditions of the system is not an easy problem. The DPC and MPC methods then help to eliminate the disadvantages of the VOC. The MPC method has been now become much interesting since it offers a general solution to a multi-goal optimization problem. In the paper, the system structures and controller parameters are briefly presented. The main evaluation factors of the active rectifier are low input current distortion (THD), a unit input power factor and stable DC output voltage. Three methods are analyzed and verified using MATLAB software and measuring experiment on a real model. The obtained results show that the VOC method achieves stable quality under different load as well as the switching frequency conditions, while the MPC method may achieve good quality with a rather high switching frequency.