Objectives:
1) To know the operation theory of vibration sensor
2) To find the suitable vibration sensor
Method:
1) By making research in the internet
Sometimes chaos begins with a low rumble or a small shake. If a sensor is involved, it might be measuring the first vibrational movements of an earthquake or a mechanical failure in an industrial setting. It's typically noise that gives use the first clue that trouble looms. There can be two aspects of vibration that we need to pay close attention if we want to avoid the trouble. The aspects are:
a) The monitoring of vibration
b) Maintenance based on sensor data to avoid future issues
As machines or the electronics and components machines begin to move back and forth, the vibration is preventing a smooth flow of energy. The flow is interrupted, hence the noise and the shake. It may be overload due to some sort of stress or the components themselves may have reached their useful life such as gears, teeth, bearing, or belts may be in process of failure.
Vibration is needed to monitor because in industrial machinery, the vibration produced are vital indicators of machinery health. by monitoring the vibration levels over time, it allows prediction of problems before serious damage can occur. Despite the advances made in vibration monitoring and analysis equipment, the selection of sensors and the way they are mounted on a machine remain critical factors in determining the success of any monitoring program. The key to proper machine monitoring however is the proper choice of sensor for the particular installation. The best instrumentation and software available will not provide the definitive information without using the proper sensor regarding the mechanical operating condition or deficiencies of the machine. The ability to monitor more than one machine parameter with the same sensor can give added insight to machine performance at a more economical cost. To select the vibration sensors, there are three parameters representing motion detected by vibration monitors. There are:
a) Displacement
b) Velocity
c) Acceleration
These parameters can be measured by a variety of motion sensors and are mathematically related. For instance, displacement is the first derivative of velocity and velocity is the first derivative for acceleration. The selection of a sensor is proportional to displacement, velocity or acceleration which depends on the frequencies of interest and the signal levels involved. Sensor selection and installation is often the most critical determining factor in accurate diagnoses of machinery condition.
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| The relationship of displacement and velocity and acceleration |
The vibration sensor that will applied for this project is piezoelectric sensors. The piezoelectric property is a reversible phenomenon. Whenever an electric excitation voltage is applied across the opposite faces of quartz crystal, it starts to vibrate and hence produces mechanical oscillations. Whenever mechanical vibrations are applied to the crystal, it produces electric potential across of oscillations depends on the physical size and the shape of the crystal. The smaller dimensions of crystals produce higher frequencies and bigger crystals produce lower frequencies.
The model type of vibration sensor is the Minisense 100 which is a low-cost cantilever-type vibration sensor loaded by a mass to offer high sensitivity at low frequencies. The pins are designed for easy installation and are solderable. Horizontal and vertical mounting options are offered as well as a reduced height version. The active sensor area is shield for improved RFI/ EMI rejection. The sensor has excellent linearity and dynamic range and may be used for detecting either continuous vibration or impacts. The mass may be modified to obtain alternative frequency response and sensitivity selection.
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| Minisense 100 Vibration Sensor |
The application of vibration sensors are:
a) Washing Machine Load Imbalance
b) Vehicle Motion Sensor
c) Anti-Theft Devices
d) Vital Signs Monitoring
e) Tamper Detection
f) Impact Sensing
Piezo Vibration Sensor Testing
Conclusion:
This week I am going to learned about the vibration sensor as it is the one of the component which is used in my project. The type of vibration sensor and the application of of it need to take note so that it is suitable to use in this project. This project will used the Minisense 100 which is a piezoelectric vibration sensor. The vibration sensor sense when the rider had a crashed. The helmet will hits the ground and the vibration sensor detects the vibrations that are created when the helmet hits the ground and then the microcontroller will send a SMS containing information about the accident and location of accident. This will help the rider to get a help in a very short time. Hence, lives can be save.
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