A Review on ANFIS based Linearization of Non Linear Sensors

Low cost sensors having high sensitivity, better resolution and linear characteristics are required for industrial applications based on instrumentation and control. Unfortunately, the natural non linear characteristic of sensor itself and also the dynamic nature of the environment, aging effect, inherent sensor’s noise and data loss due to transients or intermittent faults affects the sensor characteristics non linearly. As the transfer characteristic of most sensors is nonlinear in nature, obtaining data from such a nonlinear sensor, by using an optimized device, has always been a design challenge. Linearization of nonlinear sensor characteristic in digital environment, is a vital step in the instrument signal conditioning process. This paper gives a brief review about how to overcome this nonlinear characteristic of the sensor using artificial intelligence such as  Hybrid Neuro Fuzzy Logic (HNFL) based on digital linearization technique using VLSI technology such as Field Programmable Gate Array (FPGA)

The effects of thermistor linearization techniques on the T-history characterization of phase change materials

Phase Change Materials (PCMs) are increasingly being used in the area of energy sustainability. Thermal characterization is a prerequisite for any reliable utilization of these materials. Current characterization methods including the well-known T-history method depend on accurate temperature measurements. This paper investigates the impact of different thermistor linearization techniques on the temperature uncertainty in the T-history characterization of PCMs. Thermistor sensors and two linearization techniques were evaluated in terms of achievable temperature accuracy through consideration of both, non-linearity and self-heating errors. T-history measurements of RT21 (RUBITHERM ® GmbH) PCM were performed. Temperature measurement results on the RT21 sample suggest that the Serial-Parallel Resistor (SPR) 1 linearization technique gives better uncertainty (less than ±0.1°C) in comparison with the Wheatstone Bridge (WB) 1 technique (up to ±1.5°C). These results may considerably influence the usability of latent heat storage density of PCMs in the certain temperature range. They could also provide a solid base for the development of a T-history measuring device. © 2012 Elsevier Ltd. All rights reserved

Study and Design of a Multi-range Programmable Sensor for Temperature Measurement

In this paper, a wide-range high-precision sensor has been designed in order to accurately measure the temperature in a medium with arbitrary temperature variation and the implementation of a wide-spectrum temperature measurement system with a self-selected multi-sensor has been realized. This multi-sensor core is made up of different sensors combined to measure different temperature ranges. This concept can be used for high-precision temperature measurement in electrical capacitance tomography applications. The proposed technique is well suited for temperatures in boilers, industries, and everywhere high temperature measurement sensitivity is needed by using different combined temperature sensors of high precision

Analog to Digital Conversion Methods for Smart Sensing Systems

The new capabilities of smart sensing systems namely, adaptability, reconfiguration, lowenergy consumption and cost, between others, require a wisely selection of the methods that are use to perform analog to digital conversion. It is very important to optimize the trade-offs between, resolution, accuracy, conversion rate, and energy consumption, between others, and above all to adapt dynamically the conversion parameters for different signals characteristics and applications\\u27 purposes. Establishing the best trade-offs are even more important when signals to be digitized have different signal-to-noise ratios (S/N) ratios, different requirements of measuring accuracy and acquisition rate, their characteristics are time-variant and above all if they are sharing the same digitalization device. Very low resolution or conversion rate of data acquisition (DAQs) systems are generally not compliant with measurement systems\\u27 requirements since signal information is lost without any possible recovery procedure. Otherwise, if resolution or data acquisition rate are excessively high that means the sampling rate is much higher than its minimum value (Nyquist rate), the excessive amplitude and time resolutions provided by A/D conversion or frequency-to-digital conversion (FDC) does not improve measurements system\\u27s performance. Moreover, the excessive resolution or data acquisition rate implies an increase of hardware and software complexity, data processing load and a higher implementation cost, without any benefits. So, for any A/D or FDC conversion method the best trade-off between different conversion characteristics must be established considering applications\\u27 purposes. For example, in wireless sensing and actuating networks (WSAN) energy wastes are particularly important because a wrong choice of conversion method can affect deeply measurement system autonomy. Whenever possible, classical A/D conversion methods are being replaced by discrete A/D conversion methods that are supported by low cost microcontroller (C) (Microchip, 2010) connected to a few external resistive or capacitive components. This solution takes full advantage of Cs benefits, namely specific hardware and software capabilities and it provides a conversion rate that can be higher that several hundreds of kHz that is sufficien

NONLINEARITY COMPENSATION AND ACCURACY IMPROVEMENT METHOD FOR AN OPTICAL ROTARY ENCODER

This paper presents a method for the nonlinearity compensation of an optical rotary encoder. The proposed method is based on the application of 1) a special 4-bit mixed analog-digital circuit used for the generation of a quasi-linear signal, and 2) a two-stage nonlinear ADC which performs linearization and digital conversion of the quasi-linear signal at the same time. The quasi-linear signal is obtained by combining fragments of phase-shifted sinusoidal signals, where each fragment is presented with a 4-bit digital code. In the continuation, the quasi-linear signal is linearized with the two-stage nonlinear ADC of a compact design based on the application of a single flash ADC in both conversion stages. Additionally, the design of the flash ADC is modified so that the number of employed comparators is equal to the resolution of the flash ADC. For instance, by linearizing an optical rotary encoder using the 4-bit mixed analog-digital circuit and the 20-bit two-stage nonlinear ADC containing 10 comparators, the maximal value of the absolute measurement error can be reduced to 3.23·10-5°

Data acquisition system of a flexible solar collector

Mestrado de dupla diplomação com a Université Libre de TunisThe aim of this Master Thesis work is to create a weather station based on sensors by creating a data acquisition system with LabView in purpose to collect data for solar collector based on the European standard for solar collector testing. EN 12975-2(CEN 2006) offers two different methods for characterizing the thermal performance of solar thermal collectors: The steady state (SS) method and the quasi-dynamic method (QDT). The process of building the data acquisition system begin by choosing thermocouples and NI USB-6008 DAQ device to measure ambient temperature, LM35 sensor and NI myDAQ for the inlet mass flow measurement, for the surrounding air speed we used vernier anemometer with NI myDAQ, another thermocouple type k for surrounding air temperature measurement and a pyranometer with NI USB-6008 for global and diffuse irradiance. Hence, The main action of data acquisition systems is the sampling signals that measure real world physical conditions (voltage, current) and converting the resulting samples into digital values that can be handled, for example, by a computer. This project describes the fundamental concepts of data acquisition systems; in particular sensors, transducers, communication cabling, and system configurations