International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 05 | May -2017
p-ISSN: 2395-0072
www.irjet.net
An Approach to monitor PCB vibrations using MEMS accelerometers Rutuja.S.Kulkarni1, Dr.A.N.Cheeran2 1Student, 2Associate
Dept. of Electrical Engineering, VJTI, Mumbai, Maharashtra Professor, Dept. of Electrical Engineering, VJTI, Mumbai, Maharashtra
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Abstract - Vibration analysis is one of the principals used to
technique which may be considered the basis of diagnostic vibration measurements. [1]
monitor a particular system. It is the great need in present scenario and can be widely used in many practical applications.The paper focuses on designing a circuit board to measure PCB vibrations using grid of triaxial accelerometers. The PCB vibrations are sensed by accelerometers in all the three X, Y and Z directions. The microcontroller then samples the data from each axis of the accelerometers and performs signal conditioning of the vibration data samples. These samples are then transmitted via serial communication channel to the Data acquisition system. Finally the vibration data collection is done by Data acquisition system to generate vibration profile which is graph of Power Spectral Density (PSD) of acceleration vs frequency for the given PCB. Further the paper aims in designing a circuit board to measure vibration levels at different points on the PCB. Though there are many vibration analysis systems available, this paper is intended to design a tool that will help to study engine vibrations and can analyze amplitude and frequency factors at different positions on PCB. It will be used to measure vibration data from the PCB housed and mounted on the engine to estimate vibration input to the module and measure vibe response on the PCB for reasons like correlation with the mechanical simulation and electrical field failures.
Vibration measurement and analysis has been the accepted method to achieve various objectives like machine condition monitoring, qualification of newly designed components, prediction of faults and structural deformation problems. One of the reasons for its wide usage is without interrupting the normal operations of the machines it can monitor the vibrations of the machines. Also the development of techniques for vibration processing, computing efficiencies and reliable performance of vibration instrumentation are the reasons behind the extensive use of this technique. [1] Vibration measurement is highly excessive if conventional piezoelectric accelerometers are used. Hence, there is a need for cheaper and reliable alternative for the conventional piezoelectric accelerometers and one such cheap alternative could be Micro-Electro-Mechanical Systems (MEMS) accelerometers. [2] The use of conventional accelerometers for multiple data collection points may increase the complexity of monitoring system because of the associated electronic units that are externally connected to the accelerometers. Consequently, the need for cheaper and more reliable devices is well recognized. The main advantages of MEMS technology can be summarized as cost effective, better sensitivity and small size. [2], [4]
Key Words: Printed Circuit Board (PCB) vibrations, Micro-electro-mechanical System (MEMS) based accelerometer, vibration monitoring and analysis, Engine vibrations
1. INTRODUCTION Vibration describes an oscillating motion about a reference position. Vibration signals generally consist of many frequencies occurring simultaneously so that we cannot immediately see just by looking at the amplitude-time pattern, how many components there are, and at what frequencies they occur. Vibration is a vital characteristic of major mechanical machinery. A fundamental requirement in all the vibration work is the ability to obtain an accurate description of the vibration by measurement and analysis. The “vibration profile� of the machine will inform the operator whether the machine is operating properly or not and can offer an early warning for predictive maintenance steps. The breaking down of vibration signals into individual frequency components is called frequency analysis, a
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Impact Factor value: 5.181
Fig -1: MEMS Technology [4] Vibrations can be measured using various types of accelerometers. Most commonly used are those which utilize capacitive sensing and the piezoelectric effect to sense the displacement of the proof mass proportional to the applied acceleration. Capacitive sensing accelerometers are the ones that implement capacitive sensing and produces output in the form of voltage which is dependent on the distance between two planar surfaces. The advantages of these accelerometers include small packages that can be integrated with PCB, good stability in temperature, good
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