Design Of Signal Conditioning Circuit Research Articles

Design of signal conditioning circuit at the output end of signal source based on AD9954

The signal source based on DDS technology has the characteristics of high precision and high resolution, and is widely used in precision testing, instrumentation and other fields. However, interference signals such as high frequency harmonics and noise will inevitably appear in the output signal of the DDS chip, and even the sinusoidal signal generated by the DDS will be completely covered. This article takes ADI’s 14-bit high-precision DDS chip AD9954 as an example. I/V conversion and elliptic filter circuits are added to the output of the chip to obtain a pure sinusoidal signal. The rationality of the design is verified by multisim simulation software. This circuit provides strong support for the design and implementation of high-precision signal sources based on DDS.

Household Appliances Identification: Hands-On Integrative Workshop and Its Adaptation to a Social Distancing Context

Theoretical and practical knowledge integration is essential in Electrical Engineering. Throughout the degree, students must tackle specific problems where they can put into practice difficult concepts and test their learning. Taking this into consideration, an integrative workshop is implemented in the third year that seeks to strengthen skills such as: analysis and design of signal conditioning circuits, designing and printing circuits, signal acquisition and processing, pattern recognition and classification, integration of a system. The workshop is based on the topic of load identification which is a challenging problem, suitable for developing multiple electrical engineering concepts and also an interesting subject for the initiation of the students to research. This article shares the 2019 edition experience and its adaptation to non-classroom classes in 2020 in the context of social distancing restrictions due the coronavirus disease. The 2019 didactic proposal and the necessary modifications for 2020 are presented and analyzed. Although loosing the fruitful interaction between teachers and students in the lab in 2020, most of the hands-on activities could be maintained helped by the use of USB oscilloscopes/analyzers that give students the functionality of a lab at home. It is concluded that both editions, in spite of their different teaching modalities, achieved good academic results.

Design of Multi-function Power Factor Instrument with STM32

Background: A multifunctional power factor device based on the FFT algorithm has been designed. The digital panel can display power factor, voltage, current, frequency, phase angle, active power and reactive power. Objective: To solve the influence of the harmonic interference and the aperiodic component on the accuracy of power factor measurement. Methods: In this paper, by combining a fixed-point 256-point FFT algorithm and taking STM32 as the core microcontroller, the hardware circuit and the software program are designed respectively. The hardware circuit is tested and analyzed in practice. Among them, the hardware circuit mainly includes the main circuit design, STM32 control circuit design, EMI and second-order RC filter circuit design, sampling circuit design, and signal conditioning circuit design. The software program mainly includes the main program, AD conversion subroutine, voltage and current acquisition subroutine, LCD display subroutine and twirl factor array. FFT algorithm is achieved by the table look-up method. Results: Finally, the hardware circuit is built and the software program is debugged to test the designed device. The experimental results show that the designed power factor instrument meets the task requirements under the different types of loads. Conclusion: After processing and analyzing the measurement results, it can be concluded that: under the pure resistive load, the maximal relative error of electrical parameters is 4.49%; and under the resistive inductive load, the maximal relative error of electrical parameters is 2.86%. Both results meet the design requirements.

Enabling Cognitive Pyroelectric Infrared Sensing: From Reconfigurable Signal Conditioning to Sensor Mask Design

Poor signal-to-noise ratios (SNRs) and low spatial resolutions have impeded low-cost pyroelectric infrared (PIR) sensors from many intelligent applications for thermal target detection/recognition. This article presents a cognitive signal conditioning and modulation learning framework for PIR sensing with the following two innovations to solve these problems: 1) a reconfigurable signal conditioning circuit design to achieve high SNRs and 2) an optimal sensor mask design to achieve high recognition performance. By using a programmable system on chip, the PIR signal amplifier gain and filter bandwidth can be adjusted automatically according to working conditions. Based on the modeling between PIR physics and thermal images, sensor masks can be optimized through training convolution neural networks with large thermal image datasets for feature extraction of specific thermal targets. The experimental results verify the improved performance of PIR sensors in various working conditions and applications by using the developed reconfigurable circuit and application-specific masks.

Application of Single MEMS-accelerometer to Measure 3-axis Vibrations and 2-axis Tilt-Angle Simultaneously

This paper discusses a technique of developing an integrated sensor system, to measure the mechanical vibrations in 3-axis and the tilt-angle in 2-axis simultaneously, using only single MEMS-accelerometer. Type of MEMS-accelerometer that used in this experiment is MMA7361L, which is an analog-type acceleration sensor in the form of MEMS, with a maximum sensitivity of 800 mV/g. The MMA7361L has three outputs of voltage (V x , V y , V z ) in response to the acceleration value of each working-axis corresponding vibrating (g x , g y , g z ). By using certain techniques in the design of signal conditioning circuits, then the MMA7361L can be used to detect parameters of the vibration in 3-axis and the tilt-angle in 2-axis at the same time, simultaneously. To accommodate five output signal of the sensor system, used a data acquisition system that was built based on PIC16F876 microcontroller, which are already contained five internal ADC with 10 bits resolution. Thus, the resulting integrated sensor system becomes very simple, minimal components, and inexpensive. The experimental results show that the developed integrated sensor system has capability to measure the 3-axis vibrations and the 2-axis tilt-angle, with fairly good accuracy.

超级电容在电动自行车系统中快速充电控制的研究

级电容是具有超大容量的新型储能元件，本文针对电动自行车需频繁充电和更换蓄电池的情况，采用超级电容作为电动自行车的动力源。首先对超级电容充电控制方案进行设计；重点在于充电控制电路的硬件设计，包括驱动电路、采样隔离电路以及信号调理等电路的设计。然后对充电控制器进行软件设计，采用先恒流充电后恒压充电的工作方式。最后对充电控制系统进行建模仿真，详细分析仿真结果，验证充电方式的合理性。 Super capacitor is a novel storing energy element with large capacity. Aiming at the electric bicycle frequent charging and replacement battery, the paper adopts the super capacitor as the power source of the electric bicycle. First, the super capacitor charging control scheme is designed. The key is the hardware of charging control circuit, including the drive circuit, sampling isolation circuit and signal conditioning circuit design, etc. And then the software design of charge controller is designed, the paper adopts way of working of first constant current charging and then constant voltage charging. Finally, the simulation modeling of charging control system is designed, and the simulation results is detailed analyzed, which verify the rationality of the charging ways.

Data Acquisition System Design and Data Analysis on Automatic Transmission

An efficient data acquisition system for electronic automatic transmission test, which makes use of American NI’s data acquisition card, is designed based on Virtual Instrument. The data can be collected by the data acquisition system include automatic transmission oil pressure, solenoid duty, as well as engine speed ，turbine speed ，output shaft speed and throttle degree，and so on. The key problems of the system design are measurement method of automatic transmission solenoid duty, signal conditioning circuit design and multi-signal acquisition synchronization. Test platform is North-Benz dump truck 2627K (Its power-train assembly is replaced), of which transmission and engine use respectively HD4070PR electronic automatic transmission and BF6M1015CP electronic diesel engine. The automatic transmission shift control strategy and oil pressure characteristics of clutch or brake etc can be analyzed through test data acquisition.

An Efficient Data Acquisition System for Automatic Transmission

A data acquisition system for electronic automatic transmission test, which makes use of American NI’s data acquisition card, is designed based on Virtual Instrument. The data can be collected by the data acquisition system include automatic transmission oil pressure, solenoid duty, as well as speed of turbine and output shaft of transmission and throttle degree of engine and so on. The key problems of the system design are measurement method of automatic transmission solenoid duty, signal conditioning circuit design and how to improve sampling rate of the system. Test platform is of a armored vehicle which has equipped a high-power electronic automatic transmission. The automatic transmission shift control strategy and characteristics of throttle oil pressure etc can be obtained through test data acquisition.

Signal Conditioning Circuit Design Method Based on Case-Based Reasoning

In order to improve the R&D speed of instrument and to reduce the R&D cycle, this paper presents a signal conditioning circuit design method based on case-based reasoning (CBR). The case base stores a number of case circuits, and each circuit’s feature information is described by a set containing at least one information entity; the description methods include: according to the user’s description information on the to-be-generated circuit, generate the first information entity set of to-be-generated circuit; take the first information entity set as the search keywords, search from the case base the case circuit of all or partial information entities of the circuit to be generated; according to the degree of correlation between the preset information entity and the case circuit, obtain the degree of correlation between the first information entity set and the searched case circuit; from the said case circuits searched, select the case circuit whose correlation degree is larger than the correlation threshold value as the target circuit; output the target circuit; through accepting the users’ modification of target circuit, obtain the circuit to be generated. Experimental results show: signal conditioning circuit image generation method, which is based on case reasoning, can effectively improve the efficiency of research and development.

Digital Measuring System for Monitoring Motor Shaft Parameters on Ships

The robust measuring system for the continuous monitoring of the ship motor shaft average torque, power, and rotational speed was developed and tested. The system was designed for permanent installation in ships under realistic working conditions. The strain gage sensor is employed to measure the torque, whereas the shaft rotational speed is measured by the inductive proximity switch. The strain gage signal conditioning circuit design was highly simplified by using a high-resolution SigmaDelta A/D converter (ADC). Such an approach minimizes the overall number of analog components and the input measuring chain errors. A contactless power transmission subsystem was developed based on the specifically designed rotary transformer operating at low frequency. Strain measurement results are transmitted over the near-field low-frequency capacitive link by using a specifically designed communication protocol based on the digital modulation principle. The receiver microprocessor-based unit processes the measured data and transmits the results to the monitoring human-machine interface over some commonly used industrial analog and digital communication protocols. The principal advantages of the novel measuring system design over some state-of-the-art commercial solutions are simplicity, higher accuracy, stability, reliability, simplified calibration procedure, and contactless signal transmission and processing completely in a digital form, which, hence, reduces the most common shortcomings of similar analog-based systems.