Principle & Working Of Accelerometer

What Is An Accelerometer?

An accelerometer is an electromechanical device. It measures the acceleration forces. These forces are static, like a force of gravity of light. This device senses various types of accelerations or vibrations. Thus, it plays an essential role in vibration engineering.

Compass apps or maps in smartphones can detect the direction of a moving individual. It can do this in a couple of seconds. This is because of the presence of an axis-based motion-sensing device. It is made through the use of an accelerometer.

Possessing certain characteristics is also the main reason why we use accelerometers. Some of its major characteristics include:

• High stiffness
• Highly repeatable
• Quick rise time
• The high usable range of frequency
• Wide dynamic range
• Rugged and durable

Principle & Working Of Accelerometer

Since an accelerometer is an electro-mechanical device. Thus, it converts mechanical energy into electrical energy. The working of an accelerometer is the movement or vibration of the body.

When we keep mass on the sensor, it starts moving down like a spring. During this process, it experiences acceleration. That acceleration further transforms into several electric signals. We can use those electric signals for measuring variations in the position of the device.

The best thing about this device is that it can even detect vibration on a micro-scale. After detecting the vibration, it transforms it into the piezoelectric effect. This effect arises when stress and pressure generate energy. Further, that energy gets transformed into electric voltage.

This voltage handles producing velocity and orientation. Moreover, it also can measure static forces like gravity or dynamic forces. These forces are mainly used in smartphones and laptops. There is also a type of accelerometer, XYZ-type. This accelerometer device uses gravitational force to measure the location of any device.

Types Of Accelerometer

There are three types of accelerometers. Let us learn what they are and how they work.

CAPACITIVE MEMS ACCELEROMETER

The first one in the list of types of accelerometers is a capacitive MEMS accelerometer. The full form of MEMS is Micro-Electro-Mechanical-System. It is a commonly used accelerometer among these three.

This type of accelerometer is a fabrication technology. The function includes the detection of change in capacitance, instead of resistance. Most smartphones use this MEMS accelerometer.

PIEZORESISTIVE ACCELEROMETER

The next one is the Piezoresistive Accelerometer. It is less sensitive and is mostly used for the crash testing of vehicles. These can detect the value of applied pressure. Also, it increases its resistance in proportion.

This accelerometer measures the vibrations caused by resistance change. It is a DC-responsive accelerometer. For minor vibrations, like a gravity vector, it is very efficient.

PIEZOELECTRIC ACCELEROMETER

The third type is Piezoelectric Accelerometer. These accelerometers consist of piezoelectric materials to detect the change in acceleration. For the accurate measurement of shock and vibrations, it is useful.

There are two types of piezoelectric accelerometers. These are high impedance charge output accelerometer and low impedance output accelerometer.

The accelerometer sensors comprise crystals and ceramics. This includes lead titanate, lead zirconate, and some other materials. The purpose of the piezoelectric accelerometer is to absorb the vibrations. Further, it produces the electric signals in the exact quantity.

 Real-Life Applications Of Accelerometer

Accelerometers have innumerable uses in different industries. From smartphones to the most complex machines, accelerometers are present everywhere. Following are some of the accelerometer applications in the real world.

1. DRONES

Accelerometers play a key role in the proper functioning of drones. They stabilize the orientation mid-flight, which helps them fly correctly.

2. ROTATING MACHINERY

An accelerometer measures the vibrations in any component in the rotating machinery. Further, it also helps in finding the cause of vibration.

3. VEHICLES

This device plays a key role in saving lives from an accident. In case an accident happens, the accelerometer triggers the airbags at that moment. While experiencing a sudden shock, accelerometers present in the car send a signal. It further activates the airbags.

4. DIGITAL DEVICES

The most used digital devices include smartphones, tablets, and DSLRs. All these devices use accelerometers. Its function here is to rotate or tilt the display as per the orientation of the holding.

5. SPORTS

Sports need tracking individual performance, for which the accelerometer is here. There are many wearable devices present for athletes and sports lovers. These devices consist of gyroscopes or accelerometers which track their improvements.

6. VIBRATION MONITORING

Vibration monitoring is one of the main accelerometer applications. It examines the vibrations present in piping, equipment, and different structural components.

7. MEDICAL INDUSTRY

The medical industry is adopting new-age technologies for efficiency in their work. Thus, accelerometers find a place here as well. To inspect the change in body mass or to examine body movements, physicians use this tool. Moreover, it is also useful in the heart-rate measuring device.

These were the most used applications of accelerometers. But as already said, we can use accelerometers for innumerable purposes. Some other purposes of accelerometers are:

• Bearing Analysis
• Fatigue Testing
• Environmental Testing
• Component Durability Testing
• Gearbox Monitoring
• Biomechanics
• Building Vibration Monitoring
• Bridge Monitoring
• Impulse Response
• Drop Testing
• Ground Vibration Tests
• Impact Measurements
• Vibration Isolation
• Research & Developments
• Seismic Monitoring
• Squeak and Rattle
• Vibration Stress Screening
• Structure-borne Noise
• Quality Control
• Pyroshock
• Product Qualification
• Package Testing
• Structure Testing

How To Select An Accelerometer?

Selection for the right accelerometer is not a straightforward task. It requires a lot of consideration and testing to find the best one. The buyer must measure its vibration amplitude and frequency range. Also monitoring the temperature range of the pipe/equipment is necessary.

The other important thing is to ensure intrinsically safe or explosion-proof instruments. Also, consider the right number of axis measurements. It may be a one, two, or three-axis measurement. Also, in the accelerometers, having a maximum swing is a must.

Besides that, the other necessary factors are:

• Size and shape of the sample
• Working environment
• Whether the output is analogue or digital
• Power
• Sensitivity
• Bandwidth

How To Mount An Accelerometer?

There are different ways to mount any device or equipment. The best procedure is to read and follow the manufacturer’s manual attached. Usually, the sensors are directly mounted on the surface of the machine. This is to measure the vibrations from there. Some common mounting methods for direct surface mounting include:

• Flat Magnet Mount
• Adhesives (Epoxy/Cyanoacrylate)
• Isolating Stud
• Mounting Stud
• 2-pole Magnet Mount

For the ferromagnetic materials, we use magnet mounts as temporary mountings. This mounting type allows the sensor to move from one location to another. This helps in getting different readings.

For the ferromagnetic materials having curved surfaces, we use two-pole magnetic mounts. Also, adhesives like cyanoacrylate or epoxy are best for permanent mountings.

Wind-Up

Accelerometers are electromechanical devices. This device measures the vibration in different devices and structures. An accelerometer has innumerable functions as per its requirements. Its fundamental work is to convert mechanical energy into electrical energy. Once it detects the vibrations, it turns it into the piezoelectric effect.

Accelerometers are useful for different purposes. The main reason for this is the characteristics it shows. Some of the characteristics of accelerometers are:

• High stiffness
• Highly repeatable
• Quick rise time
• The high usable range of frequency
• Wide dynamic range
• Rugged and durable

Accelerometers are in three types. Each accelerometer type has its unique feature and work. The types of accelerometers are:

• Capacitive MEMS Accelerometer
• Piezoresistive Accelerometer
• Piezoelectric Accelerometer

The accelerometers have innumerable applications. Electromagnetic devices are commonly used in:

• Drones
• Rotating Machinery
• Vehicles
• Digital Devices
• Sports
• Vibration Monitoring
• Medical Industry

Apart from these seven accelerometer applications, these are used in many different sectors.

Selecting an accelerometer is not an easy task. It requires the buyer to consider some important parameters. The buyer must consider the following parameters while buying it.

• Measurement of its vibration amplitude and frequency range
• Monitoring the temperature range of pipe/equipment
• Intrinsically safe and explosion-proof instruments
• Must have the maximum swing

Some other factors are:

• Size and shape of the sample
• Working environment
• Whether the output is analogue or digital
• Power
• Sensitivity
• Bandwidth

To mount an accelerometer, the best way is to read and follow the manufacturer’s manual attached. Besides that, the common methods for direct surface mounting are:

• Flat Magnet Mount
• Adhesives (Epoxy/Cyanoacrylate)
• Isolating Stud
• Mounting Stud
• 2-pole Magnet Mount

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