A Low-Power High-Efficiency Adaptive Energy Harvesting Circuit for Broadband Piezoelectric Vibration Energy Harvester

Existing piezoelectric vibration energy harvesting circuits require auxiliary power for the switch control module and are difficult to adapt to broadband piezoelectric vibration energy harvesters. This paper proposes a self-powered and low-power enhanced double synchronized switch harvesting (EDSSH) circuit. The proposed circuit consists of a low-power follow-up switch control circuit, reverse feedback blocking-up circuit, synchronous electric charge extraction circuit and buck-boost circuit. The EDSSH circuit can automatically adapt to the sinusoidal voltage signal with the frequency of 1 to 312.5 Hz that is output by the piezoelectric vibration energy harvester. The switch control circuit of the EDSSH circuit works intermittently for a very short time near the power extreme point and consumes a low amount of electric energy. The reverse feedback blocking-up circuit of the EDSSH circuit can keep the transmission efficiency at the optimal value. By using a charging capacitor of 1 mF, the charging efficiency of the proposed EDSSH circuit is 1.51 times that of the DSSH circuit.

Modelling of Heat Transfer Processes in Heat Exchangers for Cardiopulmonary Bypass

A model of the heat exchange process in the heat exchanger of the cardiopulmonary bypass device is proposed which allows for automation of the process of temperature regulation in the cardiopulmonary bypass with an accuracy of ±1 °C during cardiac surgery under controlled cooling and warming of the patient’s heart and brain. The purpose of this research is to create a concept and model of the temperature control circuit using the MSC Easy5 system, the creation of mathematical models of blocks of the temperature control circuit, and the description of the principle of temperature control in the cardiopulmonary bypass circuit. The model of the temperature control loop in the heat exchanger of the heart-lung machine was created using the MSC Easy5 system with a programmable microcontroller. The microcontroller implements a specialized temperature control algorithm in the C language. The model allows the creation of a full-fledged virtual prototype of a temperature control device in a heat exchanger, and helps to conduct virtual tests of the developed device at the design stage. The model identifies control system flaws and influences decisions made before producing an official prototype of the product.

SYNTHESIS METHODS OF SELF-CHECKING COMBINATIONAL DEVICES OF AUTOMATIC CONTROLS BASED ON LOGICAL COMPLEMENT TO THE EQUILIBRIUM 1-OUT-OF 4 CODE

The article is devoted to the development of the logical complement method for the synthesis of self-checking digital devices and systems. The article highlights the features of using the equilibrium 1-out-of 4 code for the synthesis of integrated control circuits of combinational logic devices by the method of logical complement. The basic structures of the organization of built-in control schemes by the method of logical complement to the equilibrium 1-out-of 4 code are described and several ways of organizing control schemes are considered. The fi rst one implies the control of devices with the allocation of outputs fours and the use of conversion of three outputs out of four in the basic structure. There is another way of organizing the control circuit by the method of logical complement to the equilibrium code and it involves the search for outputs triplets and their addition to the four-digit code word of the 1-out-of 4 code by directly connecting the output of the supervisor logic block to the tester input without any signal conversion. The third method is associated with the use of a basic structure with the circuit for the preliminary signal compression from the unit under test and the reduced number of outputs control. The article presents the results of experimental studies for each of the methods of organizing the built-in control circuit and estimates the structures technical implementation complexity as well as the probability of detecting errors at the outputs of the unit under test when single-stuck faults are introduced. In many cases the logical complement method allows to synthesize simpler self-checking devices compared to the duplication method with high rates of error detection at the unit under test outputs.

Study on the Lower Extremity Rehabilitation Device RHleg

<p class="0abstract">This paper introduces a device to support lower extremity rehabilitation for stroke patients. First, the device's mechanical structure has been presented; the device has a simple structure and fully meets the exercise function for the patient. The equipment is controlled by control and monitoring software, which is designed from Visual Basic software. The control circuit is the Arduino 2560 circuit, responsible for receiving the angle sensor signal and measuring the current during operation. In addition, the control circuit provides control signals to the actuator and communicates with the software using the rs232 cable. Next, the mathematical model of the device has been established, and we use MatLab software to simulate the response of the device to the PID controller. Simulation results for fast response time and slight overshoot. Finally, an experiment on volunteers was conducted, the results showed that the device was stable and safe to operate. Thus, the RHleg device has been successfully designed and manufactured, tested on volunteers with good results, and this is the basis for us to continue moving towards patient testing.</p>

Test and Analysis of Stepper Motor’s Noise in HVAC’s Ventilation Valve

With the application of automotive air conditioning being more popular, higher requirements on automotive air conditioning’s comfort have been put forward, noise is an important criterion about comfort. BDC motor controlling ventilation valve’s noise is mainly caused by brush and commutator, but stepper motor doesn’t have it and stepper motor is cheap and easy-controlling. In this paper, the principle of microstepping drive technology is discussed in detail, the control circuit block diagram and the application of the stepping motor’s control system are introduced. The noise of BDC motor and stepper motor controlling ventilation valve is measured in the semi-anechoic room, BDC motor produces peak noise at the start and stop during the working of motor, stepper motor’s noise is slight and smooth-going; current waveforms have been measured in the microstepping drive, the results show microstepping drive makes current waveform more smooth-going and stepper motor’s noise is lower. So it is a tendance stepper motor will replace BDC motor to control ventilation valve, and the microstepping drive can meet different requirements for merchant’s control.