As you can imagine with a large proportion of engineering activities, choosing the incorrect tool may have serious implications on the results of your measurements. The information contained below is to help visitors make a more informative decision on an accelerometer sensor which is most appropriate for their requirements.
Selecting the correct accelerometer depends on several technical factors including measurement range, frequency response, sensitivity, environmental conditions and whether static acceleration needs to be measured. Engineers typically choose between AC-response and DC-response technologies based on the application's vibration profile and required measurement accuracy.
In general, there are two widely known types:
An AC-Responsive accelerometer means that the output is AC coupled. Essentially this means an AC coupled device cannot be used to fully measure static acceleration such as gravity and constant centrifugal acceleration meaning that it is only suitable for measuring dynamic events.
IEPE (Integrated Electronics Piezo-Electric) accelerometers are the industry standard for vibration monitoring because they provide excellent signal quality, high bandwidth and simple installation using constant-current power supplies. They are commonly used in machine condition monitoring, modal testing and industrial diagnostics
A DC-Responsive accelerometer means the output is DC coupled, meaning that this can respond down to zero Hertz (Hz). This ultimately means that it can be used to measure static, as well as dynamic acceleration. It is important to note however that measuring static acceleration is not the only reason a DC-response accelerometer should be selected.
MEMS accelerometers can measure both static and dynamic acceleration, making them ideal for tilt sensing, crash testing, structural monitoring, robotics and inertial navigation. Their ability to measure signals down to 0 Hz makes them the preferred solution whenever long-duration events or gravitational acceleration must be captured.
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An accelerometer is a sensor that measures acceleration along one or more axes. An accelerometer sensor detects changes in motion and converts the mechanical response into an electrical signal that can be recorded and analysed. Acceleration is commonly measured in metres per second squared (m/s²) or as a multiple of gravitational acceleration (g). Accelerometers can be used to measure dynamic events such as vibration and shock, while DC-response accelerometers can also measure static acceleration, including gravity. This makes them useful for applications ranging from machine condition monitoring and automotive testing to aerospace, structural monitoring, robotics and research.
An accelerometer sensor works using the principle of inertia. When the sensor experiences acceleration, an internal sensing element responds to the movement relative to the sensor housing. Depending on the technology, this change can generate an electrical charge, alter capacitance or change electrical resistance. The resulting electrical output represents the acceleration being measured. Piezoelectric accelerometers are particularly suited to dynamic vibration and shock measurements, while MEMS and other DC-response accelerometers can measure both static and dynamic acceleration.
A large proportion of vibration studies that are made, require the knowledge of displacement, velocity and most importantly acceleration. These three elements helps engineers seek in designing of validating a structure / project. Most of the time, the g value provides good reference, however the other two (velocity and displacement) are two key variables that are also needed in most design calculations. To derive velocity and displacement from the output of acceleration, the signal from the accelerometer is not only integrated, by doubly integrated respectively in both analog and digital domains.
Acceleration, velocity and displacement are mathematically related. Velocity is obtained by integrating acceleration once, while displacement is calculated by integrating acceleration twice. This relationship enables engineers to analyse machine health, structural integrity and dynamic behaviour using a single accelerometer measurement.
This is where an AC-response may run into some trouble due to the output of this device never being able to track the peak of the half-since input due to the intrinsic limitation imposed by its RC time constant. This behaviour is well understood in vibration analysis and is one of the primary reasons engineers specify DC-response accelerometers for low-frequency events, shock testing and structural monitoring where baseline stability is essential.
Here's a quick picture to illustrate the problem:
Acceleration vs Time showing the relationship between AC and DC response
At the end of the half-sine pule, it's important to note that the output of the AC coupled will produce an undershoot (more commonly known as an offset) for the very same reason. The red tracing line in the graph above depicts the output of an AC coupled device following a long duration half-sine input.
This example is a commonly occurring trouble shooting problem that we hear from clients across a wide range of industries.
They are sensors designed to measure proper acceleration in various industries and devices. They're utilized in applications such as automotive systems (airbag deployment, vehicle stability control), aerospace (flight control systems), medical devices, robotics and industrial machinery (vibration monitoring). They are also widely used for vibration checks, shock tests, structural monitoring, and product development where precise motion data is required. Accelerometers are fundamental sensors across modern engineering because they convert physical movement into measurable electrical signals. They enable engineers to monitor equipment health, improve product safety, optimise designs and detect faults before costly failures occur.
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