Accelerometers are sensors used to measure acceleration, vibration, shock, tilt and motion. They are widely used in machine-condition monitoring, vibration testing, automotive systems, aerospace, robotics, industrial automation, structural testing, consumer electronics and research.
Different accelerometer technologies are optimized for different tasks. MEMS capacitive accelerometers can measure static acceleration and low-frequency motion, piezoelectric accelerometers are widely used for dynamic vibration, and piezoresistive accelerometers are commonly selected for shock and high-g measurements.
This guide explains how accelerometers work, compares the main sensor types, covers acceleration units, sensitivity, frequency range, single-axis and triaxial measurement, vibration and shock applications, mounting, calibration and the main criteria for selecting an industrial accelerometer.
What Is an Accelerometer?
An accelerometer is a sensor that measures acceleration acting along one or more defined axes.
Acceleration is the rate at which velocity changes with time. Depending on sensor technology, an accelerometer can respond to motion caused by vibration, impact, gravity, tilt or changes in vehicle and machine velocity.
Accelerometers can be supplied as:
- small MEMS electronic sensors
- industrial vibration sensors
- laboratory measurement accelerometers
- high-g shock sensors
- single-axis sensors
- triaxial sensors
- analog or digital-output devices
What Do Accelerometers Measure?
Accelerometers directly measure acceleration along their sensitive axis or axes.
Common units include:
- metres per second squared (m/s²)
- g, representing acceleration relative to standard gravity
One standard g is approximately 9.80665 m/s².
Acceleration data can also be processed to estimate other motion quantities. For example, vibration velocity can be obtained by integrating acceleration over time, and displacement can be estimated through further integration. These derived results require appropriate filtering and signal processing because small offsets and low-frequency noise can accumulate during integration.
Do Accelerometers Measure Gravity?
Accelerometers that have a DC response, including many MEMS capacitive accelerometers, can respond to the apparent acceleration associated with gravity.
This allows them to determine tilt or orientation relative to the gravity vector when the sensor is not undergoing significant dynamic acceleration.
Many piezoelectric accelerometers, however, are AC-coupled dynamic sensors and do not provide a useful static gravity measurement. They are intended for vibration and changing acceleration rather than constant acceleration.
How Do Accelerometers Work?
Most accelerometers contain a small proof mass connected to a mechanical structure inside the sensor.
When the sensor housing accelerates, inertia causes the proof mass to move or generate force relative to the housing. The sensor measures this mechanical response and converts it into an electrical signal.
The exact conversion mechanism depends on the accelerometer type:
- capacitive sensors measure changes in capacitance
- piezoelectric sensors generate electrical charge
- piezoresistive sensors measure resistance changes caused by strain
- servo accelerometers use closed-loop force balancing
Main Types of Accelerometers
MEMS Accelerometers
MEMS accelerometers are microelectromechanical sensors manufactured using semiconductor fabrication techniques.
They contain microscopic mechanical structures, commonly including a proof mass suspended by flexible elements. Movement of the proof mass is detected electrically.
MEMS accelerometers are widely used because they can be:
- small
- low power
- multi-axis
- integrated with digital electronics
- cost effective in high-volume applications
Applications include vehicles, industrial monitoring, inertial measurement units, robotics, mobile devices and embedded control systems.
Capacitive Accelerometers
Capacitive accelerometers measure acceleration from changes in capacitance caused by movement of the proof mass.
In a typical MEMS design, the proof mass contains movable electrodes positioned near fixed electrodes. Acceleration changes the spacing between the electrodes, causing a measurable capacitance difference.
Capacitive accelerometers can measure static and dynamic acceleration and are therefore well suited to:
- tilt measurement
- low-frequency motion
- vehicle dynamics
- inertial sensing
- structural monitoring
Piezoelectric Accelerometers
Piezoelectric accelerometers use a piezoelectric element that produces electrical charge when subjected to mechanical force.
Acceleration causes the internal seismic mass to load the piezoelectric element. The generated charge is proportional to the dynamic force and therefore to acceleration within the calibrated operating range.
Piezoelectric accelerometers are widely used for:
- machine vibration analysis
- bearing monitoring
- modal testing
- structural vibration
- engine and turbine testing
- high-frequency dynamic measurements
Traditional piezoelectric sensors do not measure true static acceleration because their electrical output decays under constant loading.
IEPE / ICP Accelerometers
IEPE accelerometers contain integrated electronics that convert the high-impedance output of a piezoelectric sensing element into a low-impedance voltage signal.
IEPE is a generic term for this constant-current-powered sensor interface. ICP is a widely recognized proprietary name used for a similar integrated-electronics concept.
IEPE sensors simplify industrial vibration measurement because the same two conductors can carry both sensor power and the dynamic measurement signal.
Charge-Output Piezoelectric Accelerometers
Charge-output accelerometers produce a high-impedance electrical charge signal and require a suitable charge amplifier or signal conditioner.
They can be advantageous in high-temperature environments where integrated electronics cannot tolerate the process temperature.
Piezoresistive Accelerometers
Piezoresistive accelerometers use strain-sensitive resistive elements mounted on or formed into the supporting structure of the proof mass.
Acceleration causes the structure to deform, changing resistance. The resistance change is converted into an electrical output, often using a bridge circuit.
Piezoresistive accelerometers can provide DC response and are commonly used for:
- crash testing
- impact testing
- high-g shock measurement
- automotive safety testing
- pyrotechnic and ballistic test applications where suitable
Servo / Force-Balance Accelerometers
Servo accelerometers use closed-loop feedback to keep the internal proof mass near a controlled reference position.
The force required to rebalance the mass is proportional to acceleration.
These sensors can provide excellent low-frequency and DC performance and are used in precision navigation, inertial systems and specialized measurement applications.
Triaxial Accelerometers
Triaxial accelerometers measure acceleration along three mutually perpendicular axes, usually labeled X, Y and Z.
They are useful when the direction of vibration is not known in advance or when simultaneous multi-axis measurement is required.
Applications include:
- machine-condition monitoring
- structural testing
- vehicle dynamics
- modal analysis
- inertial measurement units
Seismic Accelerometers
Seismic accelerometers are optimized for very low-frequency and low-amplitude motion.
They are used for structural monitoring, geophysical measurements, civil engineering and other applications where very small accelerations must be detected.
High-g Accelerometers
High-g accelerometers are designed to survive and measure very large acceleration levels during impacts and shocks.
They prioritize high measurement range, mechanical survivability and transient response rather than the extreme sensitivity required for low-level vibration.
Accelerometer Type Comparison
| Type | Working Principle | Static / DC Response | Typical Applications |
|---|---|---|---|
| MEMS capacitive | Capacitance change from proof-mass displacement | Yes | Motion, tilt, vehicles, embedded systems |
| Piezoelectric charge | Piezoelectric charge generated by dynamic force | No true static response | Dynamic vibration and high-frequency testing |
| IEPE piezoelectric | Piezoelectric element with integrated electronics | No true static response | Industrial vibration and modal testing |
| Piezoresistive | Resistance change caused by structural strain | Yes | Shock, crash and high-g testing |
| Servo / force balance | Closed-loop rebalance force | Yes | Precision navigation and low-frequency measurement |
Are Accelerometers Analog or Digital?
Accelerometers can have either analog or digital outputs.
An analog accelerometer can provide:
- voltage proportional to acceleration
- charge output
- IEPE voltage signal
- bridge output
A digital accelerometer contains internal analog-to-digital conversion and communicates through an interface such as SPI, I²C or another digital protocol.
Digital-output MEMS devices are common in embedded electronics, while analog IEPE and charge accelerometers remain common in professional vibration measurement.
Single-Axis vs Triaxial Accelerometers
| Factor | Single-Axis | Triaxial |
|---|---|---|
| Measured directions | One axis | Three orthogonal axes |
| Size and mass | Often lower | Often higher |
| Channel count | One measurement channel | Three channels |
| Best use | Known vibration direction | Multi-direction or unknown vibration |
| Typical application | Bearing radial measurement | Machine, structural and vehicle testing |
Accelerometer vs Gyroscope
An accelerometer and gyroscope measure different motion quantities.
| Sensor | Primary Measurement | Typical Units |
|---|---|---|
| Accelerometer | Linear acceleration | m/s² or g |
| Gyroscope | Angular velocity / rotation rate | °/s or rad/s |
Combining accelerometers and gyroscopes provides much more complete motion information than either sensor alone.
An inertial measurement unit, or IMU, commonly combines a three-axis accelerometer and three-axis gyroscope. Some IMUs also include a magnetometer.
Accelerometer vs G-Sensor
The term G-sensor generally refers to an accelerometer, especially in automotive, consumer-electronics and event-recording applications.
The name emphasizes that acceleration can be expressed in multiples of g.
For engineering specifications, the term accelerometer is more precise because it includes a wide range of sensor technologies and measurement ranges.
Accelerometer vs Vibration Sensor
An accelerometer is one type of vibration sensor.
Vibration can be measured as acceleration, velocity or displacement. An accelerometer measures acceleration directly, while signal processing can convert acceleration into velocity or displacement over suitable frequency ranges.
Other vibration-sensing technologies include velocity transducers, displacement probes and laser vibrometers.
Accelerometers for Vibration Measurement
Industrial vibration monitoring commonly uses piezoelectric or IEPE accelerometers mounted on machine housings.
They can detect vibration associated with:
- bearing defects
- unbalance
- misalignment
- gear problems
- looseness
- resonance
- impact events
The accelerometer must have sufficient sensitivity and frequency response for the faults or vibration phenomena being investigated.
Accelerometers for Vibration Testing
Accelerometers are also used during controlled vibration tests on shakers and test machines.
Typical test roles include:
- control accelerometer on the test fixture
- response accelerometers on the test article
- modal-analysis measurement
- random vibration testing
- sine sweep testing
- shock-response measurement
Test accelerometers should be selected with attention to mass, frequency range, mounting, transverse sensitivity and cable behavior.
What Is Accelerometer Sensitivity?
Sensitivity describes how much electrical output the accelerometer produces for a given acceleration.
Common sensitivity units include:
- mV/g for IEPE and voltage-output accelerometers
- pC/g for charge-output piezoelectric accelerometers
- mV/(m/s²)
- digital counts per g for some digital sensors
A high-sensitivity accelerometer produces a larger signal for small acceleration levels, which can improve measurement of low-amplitude vibration.
However, high sensitivity is normally associated with a lower maximum measurement range. A shock application can require much lower sensitivity so the sensor can measure very large acceleration without saturating.
Accelerometer Measurement Range
The acceleration range defines the maximum positive and negative acceleration that can be measured without exceeding the sensor's specified output range.
Typical applications can require anything from fractions of g to thousands of g.
Select enough range to cover normal and expected transient loads, but avoid choosing a range far larger than necessary if low-level resolution is important.
Accelerometer Frequency Range
Frequency range defines the vibration frequencies the accelerometer can measure within a specified amplitude tolerance.
The usable range is influenced by:
- sensor mechanical design
- resonant frequency
- mounting method
- signal conditioning
- cable and electronics
A vibration accelerometer should not be selected only from its maximum g range. The frequency range must also cover the vibration phenomena of interest.
Accelerometer Resonance
Every mechanical accelerometer has natural resonances.
As measurement frequency approaches the sensor's mechanical resonance, output can increase significantly and no longer represent acceleration accurately.
Manufacturers therefore specify a usable frequency range below resonance.
Mounting stiffness strongly affects the installed resonance and high-frequency performance.
Accelerometer Noise
Noise limits the smallest acceleration that can be measured reliably.
Noise can originate from:
- sensor electronics
- thermal effects
- signal-conditioning electronics
- electromagnetic interference
- cable movement
- quantization in digital sensors
Low-noise accelerometers are important for structural, seismic and precision low-frequency measurement.
What Is Transverse Sensitivity?
An ideal single-axis accelerometer responds only to acceleration along its sensitive axis.
Real sensors also show a small response to acceleration perpendicular to that axis. This is called transverse or cross-axis sensitivity.
Low transverse sensitivity is important when vibration in non-measurement directions is much larger than the desired signal.
Static vs Dynamic Acceleration
Static acceleration is constant or changes very slowly, while dynamic acceleration changes with time.
Examples:
- static / low frequency: gravity, tilt, steady vehicle acceleration
- dynamic: machinery vibration, impact, shock, acoustic vibration
MEMS capacitive and piezoresistive accelerometers can measure DC acceleration. Piezoelectric accelerometers are normally selected for dynamic acceleration rather than true static measurement.
Accelerometers in Aviation
Aircraft use accelerometers in flight-control, navigation, structural monitoring, flight-data and test systems.
In an inertial navigation system, accelerometers measure linear acceleration along defined body axes. Their data is combined with gyroscope measurements and navigation algorithms to estimate motion and attitude.
Flight-test accelerometers are also used to measure structural loads, vibration and dynamic response.
Accelerometers in Cars
Vehicles use accelerometers for several functions, depending on vehicle architecture.
Examples include:
- airbag and crash detection
- electronic stability systems
- vehicle dynamics
- inertial navigation
- active suspension and chassis control
- testing and development
Automotive sensors must tolerate shock, vibration, temperature extremes and long service life.
Accelerometers in Robotics
Robots use accelerometers to measure motion, tilt and dynamic behavior.
When combined with gyroscopes, accelerometers contribute to orientation estimation and stabilization in mobile robots, drones and balancing systems.
They are also used for collision detection, motion monitoring and machine-health measurements.
Accelerometers for Machine Condition Monitoring
Accelerometers are among the most common sensors used for rotating-equipment condition monitoring.
Typical monitored assets include:
- motors
- pumps
- fans
- compressors
- gearboxes
- turbines
- spindles
A permanently installed accelerometer can feed vibration data to a condition-monitoring system, while portable measurement systems can use temporary sensors during inspection routes.
Accelerometers for Shock and Impact Measurement
Shock measurement requires a sensor capable of handling large, rapidly changing acceleration.
Selection should consider:
- maximum expected g level
- shock duration
- sensor resonance
- frequency bandwidth
- mounting stiffness
- data-acquisition sample rate
- mechanical survivability
Piezoresistive accelerometers are commonly used in high-g transient measurements because they provide DC response and can be designed for very large acceleration ranges.
How Should an Accelerometer Be Mounted?
Mounting is a critical part of vibration measurement because poor mechanical coupling can change the measured frequency response.
Common mounting methods include:
- stud mounting
- adhesive mounting
- magnetic bases
- wax or temporary adhesive
- handheld probes for approximate measurements
Stud mounting generally provides the stiffest connection and best high-frequency response when the machine and sensor support it.
Magnetic and probe mounting are convenient but usually reduce usable high-frequency performance.
Where Should an Accelerometer Be Placed?
The sensor should be placed where the measured motion represents the component or structural behavior of interest.
For rotating machinery, common positions are near bearing housings because vibration forces are transmitted through the bearings into the machine structure.
Avoid flexible covers, thin panels and poorly attached brackets unless those parts are the actual measurement target.
The sensitive axis should align with the desired measurement direction.
What Is Accelerometer Mass Loading?
Attaching an accelerometer adds mass to the test structure.
If the sensor mass is significant compared with the local mass of a lightweight component, it can change the vibration behavior being measured.
This effect is called mass loading.
Miniature accelerometers are often selected for thin structures, small components and modal testing to minimize this influence.
Accelerometer Cables and Signal Integrity
Cables can affect measurement quality, particularly with charge-output and high-impedance sensors.
Important considerations include:
- cable capacitance
- electromagnetic noise
- connector security
- cable motion
- temperature
- strain relief
IEPE sensors provide a low-impedance output that is well suited to longer cable runs in many industrial vibration applications.
Accelerometer Signal Conditioning
The signal-conditioning requirement depends on sensor type.
- IEPE accelerometers require constant-current excitation and AC-coupled signal acquisition.
- charge accelerometers require a charge amplifier or compatible input.
- piezoresistive accelerometers can require bridge excitation and amplification.
- MEMS analog sensors can require regulated power, filtering and analog-to-digital conversion.
- digital MEMS sensors communicate through their specified digital interface.
Sampling Rate for Accelerometer Measurements
A data-acquisition system must sample fast enough to capture the highest frequency of interest.
In practice, vibration systems use anti-alias filtering and a sampling rate higher than twice the highest desired analysis frequency.
Shock measurements can require particularly high sample rates because short-duration events contain high-frequency content.
How Are Accelerometers Calibrated?
Accelerometer calibration determines the relationship between applied acceleration and sensor output.
A common dynamic calibration method mounts the accelerometer on a vibration exciter together with or relative to a reference accelerometer.
The system applies a known sinusoidal vibration and compares the device-under-test output with the reference acceleration.
Calibration can determine:
- sensitivity
- frequency response
- phase response where required
- transverse sensitivity in specialized tests
Reference and Back-to-Back Calibration
In a back-to-back comparison calibration, a reference accelerometer and the accelerometer under test are mounted together so they experience the same motion.
The reference sensor provides the known acceleration, while the DUT output is used to calculate its sensitivity.
The mechanical mounting between the shaker, reference and DUT must be stiff and correctly aligned to avoid calibration error.
Static Calibration of DC Accelerometers
DC-response accelerometers can be checked using gravity as a known acceleration reference for basic low-frequency verification.
Changing the sensor orientation relative to gravity produces predictable acceleration components along the sensor axis.
This method is useful for low-g MEMS and inertial sensors but does not replace full dynamic calibration when frequency response or vibration sensitivity must be characterized.
How Often Should Accelerometers Be Calibrated?
There is no universal calibration interval for every accelerometer.
The interval should consider:
- measurement criticality
- frequency of use
- shock exposure
- temperature exposure
- mounting wear
- previous calibration history
- quality-system requirements
Reference and laboratory accelerometers normally require more formal calibration control than sensors used only for approximate machine screening.
How to Choose an Accelerometer
1. Define Static or Dynamic Measurement
If you need tilt, gravity or steady acceleration, select a DC-response technology such as MEMS capacitive, piezoresistive or force-balance. For machine vibration, piezoelectric or IEPE sensors are commonly used.
2. Define the Acceleration Range
Estimate normal and transient g levels. Select sufficient range to prevent overload while retaining useful sensitivity for the smallest signal.
3. Define the Frequency Range
Identify the lowest and highest vibration frequencies that matter to the application.
4. Choose Sensitivity
Low-level vibration benefits from higher sensitivity, while high-g shock requires lower sensitivity and greater range.
5. Choose Single-Axis or Triaxial Measurement
Use a single-axis sensor when the direction is known and weight or channel count matters. Use triaxial sensors when simultaneous three-direction measurement is required.
6. Check Sensor Mass
For small or flexible structures, choose a lightweight accelerometer to minimize mass loading.
7. Define the Mounting Method
Stud mounting provides strong high-frequency coupling, while magnetic and adhesive methods improve installation convenience.
8. Choose Output Type
Select IEPE, charge, analog voltage, bridge or digital output according to the available data-acquisition and signal-conditioning system.
9. Evaluate Environmental Conditions
Check operating temperature, moisture, chemicals, radiation, magnetic fields and hazardous-area requirements.
10. Check Shock and Overload Limits
The sensor must survive unexpected impacts even when those events exceed the normal measurement range.
11. Define Calibration Requirements
Determine whether sensitivity calibration, full frequency-response calibration or traceability documentation is required.
Explore accelerometers from industrial manufacturers and suppliers on FactoryMore: Accelerometers.
Accelerometer Selection by Application
| Application | Common Choice | Important Factors |
|---|---|---|
| Machine vibration | IEPE piezoelectric | Sensitivity, frequency range, mounting |
| Low-frequency motion / tilt | MEMS capacitive | DC response, noise and bias stability |
| Crash / shock testing | Piezoresistive high-g | Range, shock survivability, bandwidth |
| Modal testing | Miniature piezoelectric / IEPE | Low mass, frequency response, phase |
| Navigation / inertial sensing | MEMS or force-balance | Bias, scale factor, noise and temperature stability |
| High-temperature vibration | Charge-output piezoelectric | Temperature rating and remote charge amplifier |
Common Accelerometer Selection Mistakes
- Using a piezoelectric accelerometer for static tilt: most piezoelectric vibration sensors cannot measure constant acceleration.
- Selecting by g range only: frequency range, noise and sensitivity are equally important.
- Ignoring resonance: measurements near sensor or mounting resonance can be misleading.
- Using a sensor that is too heavy: mass loading can change the vibration of lightweight structures.
- Poor mounting: magnets, soft adhesives and handheld probes can reduce high-frequency response.
- Incorrect axis orientation: a single-axis accelerometer must be aligned with the intended measurement direction.
- Using incompatible signal conditioning: IEPE, charge and bridge sensors require different interfaces.
- Ignoring cable motion: cable movement can add noise, especially with high-impedance signals.
- Insufficient sample rate: high-frequency vibration and shock can be missed or aliased.
- Skipping calibration: sensor sensitivity can change after severe shock, thermal exposure or long-term use.
How Do You Test an Accelerometer?
A basic functional check depends on sensor type.
Possible methods include:
- checking sensor bias or supply condition
- orienting a DC accelerometer with and against gravity
- applying known vibration using a shaker or vibration calibrator
- comparing output with a calibrated reference accelerometer
- checking each axis of a triaxial sensor separately
A functional check can confirm that the sensor responds, but formal calibration is required when quantitative sensitivity and uncertainty must be established.
Accelerometer Maintenance
Accelerometers are generally low-maintenance sensors, but measurement reliability depends on the complete installation.
Good practice includes:
- inspect connectors and cables
- keep mounting surfaces clean and flat
- check mounting studs and threads
- avoid dropping precision sensors
- protect sensitive cables from repeated flexing
- check sealing in wet or dirty environments
- verify sensitivity periodically
- recalibrate after severe overload or impact when measurement integrity is uncertain
Accelerometer Selection Checklist
Before choosing or requesting a quotation for an accelerometer, define:
- static, vibration or shock measurement
- minimum acceleration level
- maximum acceleration level
- lowest frequency of interest
- highest frequency of interest
- required sensitivity
- noise requirement
- single-axis or triaxial measurement
- sensor mass limit
- mounting method
- IEPE, charge, bridge, analog or digital output
- signal-conditioning compatibility
- operating temperature
- shock and overload survivability
- moisture and environmental protection
- cable and connector requirements
- hazardous-area requirements where applicable
- calibration and traceability requirements
Frequently Asked Questions
What are accelerometers?
Accelerometers are sensors that measure linear acceleration along one or more axes. They are used for motion, vibration, shock, tilt, machine monitoring and inertial sensing.
How do accelerometers work?
Most accelerometers use an internal proof mass. Acceleration causes the mass to move or generate force relative to the sensor housing, and the sensor converts that mechanical response into an electrical signal.
What do accelerometers measure?
Accelerometers directly measure acceleration, usually in m/s² or g. Their signals can also be processed to estimate vibration velocity and displacement over suitable frequency ranges.
What is the main function of an accelerometer?
Its main function is to quantify linear acceleration. Depending on the application, that measurement can be used to detect vibration, impact, motion, tilt or changes in speed.
What are the main types of accelerometers?
Common industrial families include capacitive MEMS, piezoelectric and piezoresistive accelerometers. Servo/force-balance sensors are another important precision type.
What is a MEMS accelerometer?
A MEMS accelerometer is a microelectromechanical sensor fabricated using semiconductor manufacturing techniques. It commonly measures proof-mass displacement capacitively and can provide compact multi-axis acceleration measurement.
What is a piezoelectric accelerometer?
A piezoelectric accelerometer uses a piezoelectric material that generates charge when mechanical force from an internal mass is applied. It is widely used for dynamic vibration measurement.
Are accelerometers analog or digital?
They can be either. Industrial vibration accelerometers commonly provide analog IEPE or charge outputs, while many MEMS sensors include digital interfaces.
Do accelerometers measure gravity?
DC-response accelerometers such as many MEMS capacitive sensors respond to gravity and can be used for tilt measurement. Typical piezoelectric vibration accelerometers do not measure constant gravity.
What is the difference between an accelerometer and a G-sensor?
G-sensor is generally another name for an accelerometer, especially in automotive and consumer-electronics applications.
What is the difference between an accelerometer and a gyroscope?
An accelerometer measures linear acceleration, while a gyroscope measures angular velocity. The two sensors are often combined in inertial measurement units.
What is the difference between an accelerometer and a vibration sensor?
An accelerometer is a type of vibration sensor that measures acceleration. Other vibration sensors can measure velocity or displacement directly.
Where should an accelerometer be placed for machine vibration?
It is commonly mounted on a rigid machine surface near the bearing or component whose vibration is being evaluated, with the sensitive axis aligned to the desired measurement direction.
How are accelerometers calibrated?
Dynamic accelerometers are commonly calibrated on a vibration exciter by comparing their output with a reference accelerometer under known sinusoidal acceleration. DC accelerometers can also be checked using gravity for low-frequency verification.