[Physics Class Notes] on Accelerometer Pdf for Exam

An accelerometer can be defined as a device that is used to measure acceleration forces, the forces which are defined by this can be static, like the continuous force of gravity or light we have seen in the case of mobile phones and it can also be said in the case of dynamics to sense movement or vibrations.

 

An accelerometer is a device that senses the different types of accelerations or vibrations. Acceleration is the change in velocity caused by the movements of a body. An accelerometer absorbs the vibrations created by the body and uses it to know the orientation of the body. A piezoelectric accelerometer has two types which are high impedance output accelerometer and low impedance output accelerometer. On the basis of the working mode, it is mainly of three types. The compression mode, the capacitive mode, and the shear mode. All of them work on sensing the vibrations.

 

Have you ever wondered about the mechanism that takes place when we use a compass app on our smartphones to somehow know in which direction the phone is pointing? The same can be said for the stargazing apps where it somehow knows where in the sky we are looking and accordingly displays the constellations. Mobile technology in smartphones uses the mechanism to identify their orientation through the use of an accelerator which is a device made up of axis-based motion sensing. It is wonderful how this motion sensor can even be used to detect earthquakes and the advancement through research on the application can be used as bionic limbs and other artificial body parts, several other quantified self movements, of the devices, also uses accelerometers.

 

Purpose of the Accelerometer

We have seen how different apps in mobile devices and other things use excel in a meter so basically, its application extends to multiple disciplines both academic and consumer or commercially. Accelerometers in laptops can be used to protect hard drives from damage. In case if the laptop were to suddenly drop while using it, the accelerometer would detect the sudden fall and immediately turn off the hard drive to avoid hitting the reading heads into the hard drive platter. Now without this, the two-day strike because of which various scratches and damages to the platter would be caused for extensive file and reading damages.

 

Another usage may be a dynamic accelerometer which is used to measure gravitational pull to determine the angle at which a device is tilted of course with respect to the earth, now by sensing the amount of acceleration the users analyze the direction in which the device is moving or analyze how the devices working.

 

Now with the given properties, this allows the user to understand the surroundings of an item better and with this small device, we can determine any movement ranging from moving uphill to the tilting of an object or whether it is flying horizontally or at an angle and downward, the best example would be smartphones when rotated they display features between portrait and landscape mode depending on how we actually tilt our phone.

 

Different components are used to make up accelerometers which can also be used to purchase as a separate device, analog and digital displays at available but for most of the technology devices these components and integrated into the main technology and then access is managed using the governing software or an operating system.

 

Now with the working also comes to the sensitivity of these devices which are quite high as they are intended and supposed to measure even the slightest minute shift and acceleration so the more sensitive the device is the more easily it can measure acceleration.

 

Accelerometer Application

Some applications of the accelerometer are:

  • The accelerometer has the capacity to sense the vibration from a micro-scale to a large scale. Even in most of the safety installations, the accelerometer is used. 

  • An accelerometer is also used in sports. The wearable devices athletes are using daily for practice and observations comprise accelerometers or gyroscopes. 

  • The physicians use it to check for gain in body mass and monitor body movements. It is also present in the devices used to check the heart rate. 

  • The piezoelectric accelerometers are used at the industrial level.

  • The most frequent accelerometer used in aerospace is Micro-Electro-Mechanical-sensors(the MEMS technology) based. The reason for using MEMS sensor-based accelerometers is that they can sense the vibrations even on a micro-scale and can also provide value on a micro-scale.

  • It is even used for satellites which are in space, as it can tolerate high pressure, heat, and vibration. 

  • For purposes like gearbox analysis, bearing analysis, rotor trim, and balance, an accelerometer plays an important role.

  • The aircraft are navigated using the accelerometer. Aircraft flight testing is another thing that requires an accelerometer. To check the characteristics of flight and to confirm its design it an accurate observation of data is expected. For that, an accelerometer named LCA-5080 is in use.

  • An accelerometer is used for safety purposes in laptops for the hard discs. Because of accelerometer sensors, we have landscape and portrait modes on our phones. Mobile phones keep changing the screen mode in landscape or portrait mode due to accelerometer applications.

Types of Accelerometer

The 3 important types of accelerometers are capacitive MEMS accelerometer, piezoresistive accelerometer, and piezoelectric accelerometer.

  • Capacitive MEMS Accelerometer- The MEMS stands for Micro-Electro-Mechanical-System. MEMS is a fabrication technology. In this type of accelerometer, the changes in capacitance are detected instead of a change in resistance. Most mobile devices use this MEMS accelerometer.

  • Piezoresistive Accelerometer- It measures the vibrations by changes in resistance. This is the accelerometer that works as DC responsive and proves efficient while measuring very little vibrations, for example, gravity vector. 

  • Piezoelectric Accelerometer- In this type the sensors are made of crystals or ceramics like lead zirconate, lead titanate, etc. This sensor absorbs the vibrations and produces the same amount of electrical signals.

Accelerometer Working Principle

The main working principle of an accelerometer is that it converts mechanical energy into electrical energy. When a mass is kept on the sensor which is actually just like a spring it starts moving down. Since it is moving down it starts experiencing acceleration. That acceleration hen gets converted into an amount of electric signal which is used for the measurements of variation in the position of the device. AThe accelerometer
can be found with both the forms analog as well as digital form devices.  No just like any other device would work happens to look like a simple circuit for some larger electronic device despite its simple appearance, it consists of many different varieties of parts which of course has their own functions and works in many ways, the most common terms would be piezoelectric effect and the capacitance sensor. The piezoelectric effect can be termed as the most common form, which uses microscopic crystal structure that becomes stress due to accelerative forces, not these crystals internal create a voltage from the stress that has been produced and the accelerometer interprets the voltage to determine its velocity and the orientation.

 

Whereas the capacitance accelerometer is used to sense changes in capacitance between microstructures located next to the device so if an accelerated force moves one of these any given structures, the capacitance will change which will cause the accelerometer to translate that capacitance into voltage for interpretation.

 

Insight Into How Does An Accelerometer Work

The accelerometer works on the movement or the vibration of the body. It can sense even the vibration on a micro-scale. It senses the vibration and converts that vibration into the piezoelectric effect. A piezoelectric effect occurs when energy is generated due to pressure and stress. That energy then gets converted into electric voltage. That voltage is used to get velocity and orientation. It can also measure static forces like gravity or dynamic forces which are in phones and laptop devices. The XYZ-type accelerometer uses the gravitational force to compare the position of the Devices.

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