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Critical questions remain regarding the need for intensity to continue NPIs as the public was vaccinated. We evaluated the association of intensity and duration of non-pharmaceutical interventions (NPIs) and vaccines with COVID-19 infection, death, and excess mortality in Europe.Data comes from Our Word in Data. We included 22 European countries from January 20, 2020, to May 30, 2021. The time-varying constrained distribution lag model was used in each country to estimate the impact of different intensities and duration of NPIs on COVID-19 control, considering vaccination coverage. Country-specific effects were pooled through meta-analysis.This study found that high-intensity and long-duration of NPIs showed a positive main effect on reducing infection in the absence of vaccines, especially in the intensity above the 80th percentile and lasted for 7 days (RR = 0.93, 95% CI: 0.89-0.98). However, the adverse effect on excess mortality also increased with the duration and intensity. Specifically, it was associated with an increase of 44.16% (RR = 1.44, 95% CI: 1.27-1.64) in the excess mortality under the strict intervention (the intensity above the 80th percentile and lasted for 21 days). As the vaccine rollouts, the inhibition of the strict intervention on cases growth rate was increased (RR dropped from 0.95 to 0.87). Simultaneously, vaccination also alleviated the negative impact of the strict intervention on excess mortality (RR decreased from 1.44 to 1.25). Besides, maintaining the strict intervention appeared to more reduce the cases, as well as avoids more overall burden of death compared with weak intervention.Our study highlights the importance of continued high-intensity NPIs in low vaccine coverage. Lifting of NPIs in insufficient vaccination coverage may cause increased infections and death burden. Policymakers should coordinate the intensity and duration of NPIs and allocate medical resources reasonably with widespread vaccination.

This paper presents a position sensorless drive system design for a Brushless DC motor (BLDCM). The rotor position of BLDCM is based on the detection circuit of back electromotive force (back EMF). The circuit senses the terminal voltage difference to provide the same rotor information and sequence as that by the Hall sensors. However, there are abnormal and unbalance characters in the original captured signals by the back EMF detection circuit, the resulting signals from the circuit cannot directly be used to provide the same functions as the Hall sensor signals in a wide operation speed range. This paper hence deals with the problems of the use by back EMF detection circuit, and proposes the compensation methods realized by the DSP to improve the quality of the rotor position signals and the performances of the resulting drive system. The proposed drive system is tested under several speed conditions. Through the experimental results by demonstrating the current responses with and without the compensation being added, the improved system shows that the performances of the proposed sensorless drive system are better on the power dissipation and with symmetric current responses. The resulting drive system is suitable for the use of battery powered electric vehicle.

Owing to the benefits of programmable and parallel processing of the field programmable gate arrays (FPGAs), they have been widely used to the realization of digital controllers and motor drive systems. In this study, we adopt the FPGA chip to realize the Linear Shaft Motor (LSM) drive system which includes the position, speed and current vector controls. Linear shaft motor is a special motor which has the magnet as the shaft and stator coils are on the forcer. Thus, it reveals a small mechanical time constant. In addition, the electrical side can be looked as a general three-phase Alternating Current (AC) system which can be powered by inverter and vector control technique can be applied to the system. The designed system needs high performance calculation ability about position/speed control and vector current control loops. The mathematical model of linear shaft motor drive system is first built and simulated by MATLAB/Simulink and the accuracy about the effect from the speed estimation method is proposed. The resulting digital model of the drive system is stored into Verilog Hardware Description Language (Verilog HDL) codes and realized by FPGA. At last, the hardware circuits as well as the power module are used to test the performance of the developed hardware system in terms of the trapezoidal velocity profile. The experimental results show that the designed system realized by FPGA has attained the desired performance.

A stepper motor is usually operated in position open-loop control for simplicity. However, in order to improve the transient and steady-state performances of the stepper motor-based drive system, a high performance stepper motor drive system is usually designed to feed the encoder signal back to form a closed-loop system such as a general servo motor drive, and high-performance position and speed loop controller can then be used to overcome the nonlinear characteristics of the motor, such as the cogging force and impacts from external load. On the other hand, the existed cogging force of the hybrid stepper motor must be solved to increase the positioning precision. The variable structure control (VSC) is insensitive to the bounded uncertainty and load disturbance, and has been known as a high-performance controller. A predefined sliding surface is used to shape the system performances, and incorporate with switching control to achieve the robustness property. Thus, we applied the VSC to implement the stepper motor drive system about the position and speed control, and the switching control is used to overcome the cogging force. The field programmable gate array (FPGA) is a good alternative to be used to realize a motor drive system by considering its programmable ability and diverse designing environment. It is easily developed as an intellectual property (IP) for future use or combined as a part of a large control system. This paper showed the procedures to develop the hardware circuits for the variable structure controller, and applied it to stepper motor position and velocity control. Functions such as PI controllers, dq-axis transformation and two-phase space vector space vector modulation (SVPWM) designed for the stepper motor drives are also shown in the paper. The system simulation and hardware circuit realization are based on MATLAB/Simulink, and realized on Altera FPGA. Simulations on MATLAB/Simulink with trapezoidal velocity profile command, and experiments with and without the load added are shown to demonstrate the hardware performances and correctness.

Owing to the benefits of programmable and parallel processing of field programmable gate arrays (FPGAs), they have been widely used for the realization of digital controllers and motor drive systems. Furthermore, they can be used to integrate several functions as an embedded system. In this paper, based on Matrix Laboratory (Matlab)/Simulink and the FPGA chip, we design and implement a stepper motor drive. Generally, motion control systems driven by a stepper motor can be in open-loop or closed-loop form, and pulse generators are used to generate a series of pulse commands, according to the desired acceleration/run/deceleration, in order to the drive system to rotate the motor. In this paper, the speed and position are designed in closed-loop control, and a vector control strategy is applied to the obtained rotor angle to regulate the phase current of the stepper motor to achieve the performance of operating it in low, medium, and high speed situations. The results of simulations and practical experiments based on the FPGA implemented control system are given to show the performances for wide range speed control.

In this paper, we implement a stepper motor drive system on field programmable gate array (FPGA), and the design is mainly based on vector control strategy. First, the control system is built by MATLAB/Simulink and simulated on Modelsim platform. Next, the resulting software system is converted into Verilog HDL codes, and implemented on an Altera Cyclone III FPGA. The stator's currents of the developed hardware system are first shown by simulation and experiment to verify the validness and performances of the vector control structure. After that, the speed responses of motor rotor are shown to prove the performances of the outer loop control system and encoder counter circuit.

Sliding mode control (SMC) is rapped for the chattering due to high gain control. However, high gain control causes the system robust. For developing a system with robustness of SMC, a servo motor motion controller combining the two-degree-of-freedom (2DOF) system and SMC is proposed. The discussed motion type is point-to-point control with the constraint of trapezoid velocity profile. SMC is designed to guide the motor motion to follow a predefined trail, and the inner 2DOF system is used to compensate the deterioration due to the adoption of load observer. The proposed hybrid system is realized on a PC-based motion controller, and the validness is verified by simulation and experimental results.

Nucleos(t)ide analogue (NA) monotherapies are typically used as the primary treatment for chronic hepatitis B (CHB) patients, including lamivudine (LAM), telbivudine (TBV), adefovir (ADV), entecavir (ETV) and tenofovir (TDF). For high-resistance NAs (LAM, TBV, ADV), they can generate excellent clinical outcomes by using response-guided therapy; however, their pharmacoeconomic profiles remain unclear in China. We aimed to evaluate the cost effectiveness between response-guided therapies and monotherapies of NAs for Chinese hepatitis B e-antigen (HBeAg)-positive and -negative CHB patients. We constructed a Markov model to simulate CHB progression associated with 12 treatment strategies using effectiveness and cost data from the published literature. We measured the lifetime costs, quality adjusted life-years (QALYs) and incremental cost-effectiveness ratios (ICERs). One-way sensitivity (especially to extend the range of the TDF price) and probabilistic sensitivity analyses were used to explore the uncertainties of the model. For both HBeAg-positive and -negative patients, no treatment strategy generated the lowest lifetime costs (US$31,185–US$31,338) and QALYs (7.54–7.58). ETV and TDF monotherapies were not dominated by other treatments, whereas, the ICER of ETV monotherapy was the lowest (US$6112/QALY–US$8533/QALY). For each high-resistance NA, compared with its monotherapy, the ICERs of its response-guided therapies were below the willingness-to-pay threshold of US$22,833/QALY. Additionally, TDF monotherapy was the preferred treatment when its price dropped to US$1820/year or lower. Among 12 treatment strategies evaluated, ETV monotherapy is the most cost-effective treatment for treatment-naive CHB patients in China. The response-guided therapies of high-resistance NAs are more cost-effective than their monotherapies.

Since the Field Programmable Gate Arrays (FPGAs) with high density are available nowadays, systems with complex functions can be realized by FPGA in a single chip while they are usually traditionally implemented by several individual chips. In this research, the drives as well as motion controller are integrated and implemented on Altera Cyclone III FPGA. The system is also evaluated by applying it to a 3-axis motion platform driven by stepping motors. Finally, experimental results of current regulator and motion controller are shown to prove the validness.

It is known that the flexibility and programmable abilities have made the FPGA widely used as controllers to the electrical machines and systems. Above all, the high density of recent developed chip results in many of the CPU cores and complicated hardware can be programmed into the chip to be as controller. Thus, this topic is based on the currently available technologies of FPGA-based system design to the parallel processing. Software and hardware co-design are shown to reach the performance, and the system’s software stream data are processed with the hardware parallel technique. This analysis enables FPGA-based control system on the parallel computing platform to achieve the simultaneous operation for 3-axis motor motion and drive system control. In that way, we chose the high density FPGA, Altera Cyclone II EP2C8Q208C8N, as the chip to develop the hardware of microprocessor, motor drive and motion controller. The developed system was practically applied to a 3-axis motion platform driven by stepping motors to evaluate the system performance.

In this study, we design the permanent magnet synchronous motor (PMSM) drive system using field programmable gate array (FPGA), and adopt variable structure control (VSC) to the current regulation. The system is first modeled with Matlab/Simulink, and the controllers in the system, including the speed PI control and current variable structure control, are hardware implemented by Verilog HDL code. Finally, the resulting hardware system is co-simulated with the software motor model to evaluate the accuracy and performance. The resulting Verilog HDL codes can be as an IP format to hardware realize the vector control for PMSM, and with the properties of robustness to the parameter variations and fast responses on the current loop control.

This paper deals with the driver design for Brushless DC Motor (BLDCM) by quasi-sinusoidal voltage source inverter with voltage space vector pulse width modulation (VSVPWM) technology. Traditionally, BLDCM is driven by six-step inverter with digital Hall sensor feedback, and has the property of trapezoidal back EMF. However, this paper presents an approach to generate a quasi-sinusoidal voltage source inverter just with the digital Hall sensor. The designed system is used to drive a 600 W BLDCM which is used on an electric vehicle. With the proposed system, the torque ripple can be reduced as compared to six-step driving.

Although coreless motors have simple linear dynamic models with low complexity level regarding to the control of usual applications, frequently some kind of noise or vibration may arise if the coreless motor is operated in a general high gain control which is easy to deteriorate the performance. Besides, for most of the drive systems, the inner-loop current controllers are usually designed to be realized by proportional plus integral (PI) controller with its easily adjustable parameters. However, systems controlled by PI scheme are weak in robustness, and their performances are easily affected by disturbances and loads, or other situations such as nonlinearity. As regards to the variable structure control (VSC), it is known that systems controlled by VSC have the properties of fast response and robustness. And in drive system design, the VSC is usually designed for the outer loop velocity/position control, and chattering phenomenon must be solved. In this study, we apply VSC to the coreless DC motor drive for current loop control to get a fast response. The controller is realized by TI TMS320F28069 DSP. The experimental results of VSC-based system are compared with the system controlled by PI controller to verify the validation of the proposed drive scheme.

This paper proposes a particular motor position control drive design via a novel sliding-mode controller. The newly designed controller is especially suitable for the motor incremental motion control which is specified by a trapezoidal velocity profile. The novel sliding-mode controller is designed in accordance with the trapezoidal velocity profile to guarantee the desired performance. A motor control system associated PC-based incremental motion controller with permanent-magnet synchronous motor is built to verify the control effect. The validity of the novel incremental motion controller with sliding-mode control method is demonstrated by simulation and experimental results.

A robust controller which is designed by employing variable-structure control and linear-quadratic method is presented for a permanent-magnet synchronous motor (PMSM) position control system. It is to achieve accurate control performance in the presence of plant parameter variation and load disturbance. In addition, it possesses the design flexibility of the conventional state feedback control. It is applied to the position control of a PMSM. Simulation and experimental results show that the proposed approach gives a better position response and is robust to parameter variations and load disturbance.

In this paper, we present the modeling, analysis, and realization of current vector control for a permanent magnet synchronous motor (PMSM) drive using MATLAB/Simulink and a field programmable gate array (FPGA). In AC motor drive systems, most of the current vector controls are realized by digital signal processors (DSPs) because of their complete and compact hardware functions. However, the performances of drive systems realized by low-cost DSP are limited by the hardware structure and computation capacity, which may lead to the difficulty of reaching a fast enough response, above all, for those motors with a small electrical time constant. Therefore, we use FPGA to speed up the calculation about the current vector control to attain a fast response. Simulations and practical experimental results are used to verify the correctness and performance of the designed full hardware system.

To develop a system with robustness, a servo motor motion controller by combining the two-degree-of-freedom (2DOF) system and sliding mode control (SMC) is proposed. The discussed motion is point-to-point control with trapezoid velocity profile. SMC is designed to guide the motor motion to follow a pre-defined trail, and the inner 2DOF scheme is used to compensate the deterioration due to the adoption of load observer. The valid ness of the hybrid scheme is demonstrated by simulation results.

A new totally invariant state feedback controller is designed by combining the classical state feedback controller and the variable-structure control (VSC). The combination of these two different control methods has the advantages of both their merits: (1) the easy design of the state feedback and (2) the strong robustness of the VSC. In other words, the system performance can be simply designed for the nominal system by using the classical state feedback, which includes such well-known techniques as the pole placement or the linear quadratic method. Then, VSC is used to ensure the control effect. To demonstrate the effectiveness of the totally invariant state feedback controller, it is applied to the position control of a synchronous reluctance motor. Simulation results are first given. In addition, a prototype hardware system is built and experimentally evaluated.

This paper proposes a dynamic output feedback controllers for variable structure systems. It is based on the concept of output feedback controllers, introduced by Zak and Hui (IEEE Trans. Automat. Control AC-38 (1993) 1509) and Kwan (IEEE Trans. Automat. Control AC-41 (1996) 1691) for matched uncertain variable structure systems in which the state is unavailable and no estimated state is required. In this paper, we extend this idea to a class of mismatched uncertain variable structure systems. A modified variable structure controllers is derived to guarantee the existence of the sliding mode by using output feedback only. The stability of the equivalent reduced-order system in the sliding mode is assured under certain conditions.

A iicwly dcsigncd optiinal control mctliod is prcswitcd. The proposcd controller is dcsigncd via combining classical sink Eecdback conlrol and variable slructure control (VSC). This new method fully matches the merits of the easy design of the linear quadratic (LQ) method and the strong robustiicss of thc VSC. Thc prescntcd optimal control mcthod is dcnlonstrated on il synchronous reluctance inotor (SytiRM). Tt is proved that the syiichronous reluctance motor can be used in position control by thc proposcd method, and the dcsigncd pcrfnroiancc can be easily obtained regardless of the disturbaiice and uncertainty. A prototype PC-based SyiiRM control system is built to verify the validity of the proposed scheme.

This paper presents a method for the design of decentralized output feedback controllers for an interconnected systems with mismatched uncertainties using a variable-structure control approach. A new reaching condition of the sliding mode is derived such that the reduced-order system is invariant to the mismatched uncertainties. In every subsystem, a new idea for a sliding mode that consists of two sets of switching surfaces is introduced, and a scheme of decentralized dynamic control using only output states is also proposed. This scheme can guarantee closed-loop stability of a sliding manifold of the composite system. Finally, a numerical example is given to illustrate the controller design method.

A Field Programmable Gate Array based system is a great hardware platform to support the implementation of hardware controllers such as PID controller and fuzzy controller. It is also programmed as hardware accelerator to speed up the mathematic calculation and greatly enhance the performance as applied to motor drive and motion control. Furthermore, the open structure of FPGA-based system is suitable for those designs with the ability of parallel processing or soft code processor embedded. In this paper, we apply the FPGA to a multi-axis velocity controller design. The developed system integrated three functions inside the FPGA chip, which are respectively the stepping motor drive, the multi-axis motion controller and the motion planning. Furthermore, an embedded controller with a soft code processor compatible to 8051 micro-control unit (MCU) is built to handle the data transfer between the FPGA board and host PC. The MCU is also used to initialize the motion control and run the interpolator. The designed system is practically applied to a XYZ motion platform which is driven by stepping motors to verify its performance.

Proportional-Integral-Derivative (PID) controllers are universal control structure and have widely used in automation systems, they are usually implemented either in hardware using analog components or in software using computer-based systems. In this work, we focused our works on building a multi-channel PID controller by Field Programmable Gate Arrays (FPGAs). Combining FPGA with high speed multi-channel serial ADC and serial DAC, the designed system has the effects of fast speed, high accuracy, compact size and cost effectiveness. It is evaluated by applying to a second-order system, and experimental results show that control performance is fulfilled the desired.

This article uses the principle of Wavelet transformation and Quad-tree structure to find the best jumper points of embroidery machine. Embroidery want the image to be cut into four equal parts. Furthermore, to judge each part if there exist two object for connection jumper point selection. For special case, the four parts divided will be extended until the best jumper point were found. According to the simulation results, our method is evidently an effective and high quality method for sewing machine for embroidering purpose.

Since the Field Programmable Gate Arrays (FPGAs) with high density are available nowadays, systems with complex functions can thus be realized by FPGA in a single chip while they are traditionally implemented by several individual chips. In this research, the control of stepping motor drives as well as motion controller is integrated and implemented on Altera Cyclone III FPGA; the resulting system is evaluated by applying it to a 3-axis caving machine which is driven by stepping motors. Finally, the experimental results of current regulation and motion control integrated in FPGA IC are shown to prove the validness.

The problem of estimating the stability regions of mismatched uncertain variable structure systems (VSS) with bounded controllers is considered. Based on Lyapunov stability theory, the estimations of stability regions such as the practical stability region (PSR), asymptotical stability region (ASR), and exponential stability region (ESR) are discussed.

The major difficulties in sliding mode control (SMC) design are the chattering phenomenon and a system with mismatched uncertainties. An effective design procedure is proposed to alleviate these two difficulties, while retaining the benefits achieved in conventional SMC design.