How does an Accelerometer Work?
By Bob Jonathan
WHAT IS AN ACCELEROMETER?
An accelerometer is an instrument for measuring acceleration, detecting and measuring vibrations, or for measuring acceleration due to gravity (inclination). Accelerometers can be used to measure vibration on vehicles, machines, buildings, process control systems and safety installations. They can also be used to measure seismic activity, inclination, machine vibration, dynamic distance and speed with or without the influence of gravity.
HOW DOES AN ACCELEROMETER WORK?
Used for calculating acceleration and measuring vibrations, the accelerometer is capable of detecting even the slightest movements, from the tilting of a building to smallest vibration caused by a musical instrument. Inside the accelerometer sensor minute structures are present that produces electrical charges if the sensor experiences any movement.
Accelerometers need to be placed on the surface of the object in order to determine the vibrations. It is not capable of work in isolation or apart from the object it is required to assess, it must be firmly attached to the object in order to give precise readings.
KINDS OF ACCELEROMETER
The two kinds of basic accelerometers are:
1. ANALOG ACCELEROMETER
At times Inputs and output readings also matter especially when it comes to determining the kind of accelerometer that needs to be placed on a certain object. If the output is digital then a digital accelerometer must be placed and vice versa. The main feature of this accelerometer is that the output tends to change when there is even a slight change in the input.
The most common type of this accelerometer is used in airbags of automobiles, to note the sudden drop in the speed of the vehicle and to trigger the airbag release. Even laptops are now being equipped with accelerometers in order to protect the hard drive against any physical dangers, caused mainly due to accidental drops.
2. DIGITAL ACCELEROMETER
The digital accelerometer is more sophisticated than the analog. Here the amount of high voltage time is proportional to the acceleration. One of its major advantages is that it is more stable and produces a direct output signal. Accelerometers are now also used in aerospace and many military applications, such as missile launch, weapon fire system, rocket deployment etc. Many a times these accelerometers are used to protect fragile equipment during cargo transportation, and report any strain that might cause a possible damage. Some companies have also managed to develop a wireless 3-axis accelerometers which are not only low in cost but are also shock durable. This 3-axis accelerometer has sensors that are used to protect mobiles and music players. Also these sensors are used in some of the devices used for traffic navigation and control.
PIEZOELECTRIC SENSOR
Depending upon the kind of work, the accelerometers vary in the way they are prepared and how they work. Some accelerometers use piezoelectricity, these are man-made. In such accelerometers the acceleration is calculated based upon the charges derived from the microscopic crystalline structures when they are accelerated due to motion.
MEMS ACCELEROMETER
Another kind works with the capacitance and the changes initiated within it as a result of some accelerative force. This technology is used from automotive industry to agriculture industry and from NASA to military researches and operations.
STRAIN GAUGE
This device is used to measure strain in an object, which is detected by a foil strain element. If the object, to which the gauge is attached is some how deformed that creates electrical charges and is known as the gauge factor.
ACCELEROMETER IS USED IN:
AUTOMOTIVE INDUSTRY
Due to high demand and wide spread use of accelerometers in the automotive industry and new hi-tech technology, these sensors are now light weight and are available at low cost and reduced prices.
MICROPHONES
Microphones also carry accelerometers. That is how they are able to detect the minute frequencies.
ROBOTICS
The forces that can cause vibrations which are detected by the accelerometer can be static, dynamic or gravitational. Certain accelerometers are rated G. G stands for Gravity. Such accelerometers are used mostly in robotics. They are more sensitive to motion and can be triggered at the slightest changes in gravitational pulls.
Read more about Accelerometer.
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Memsic 2125 Accelerometer Demo Kit
Acceleration, Tilt, and Rotation Measurement
Introduction
The Memsic 2125 is a low cost, dual-axis thermal accelerometer capable of measuring dynamic acceleration (vibration) and static acceleration (gravity) with a range of ±2 g. For integration into existing applications, the Memsic 2125 is electrically compatible with other popular accelerometers. What kind of things can be done with the Memsic 2125 accelerometer? While there are many possibilities, here’s a small list of ideas that can be realized with a Memsic 2125 and the Parallax BASIC
Stamp® microcontroller:
- Dual-axis tilt sensing for autonomous robotics applications (BOE-Bot, Toddler, SumoBot)
- Single-axis rotational position sensing
- Movement/Lack-of-movement sensing for alarm systems
2g Tri-Axis Digital Accelerometer
The KXP84-2050 is a tri-axis silicon micromachined accelerometer with a full-scale output range of ±2g (19.6m/s2). The sense element is fabricated using Kionix’s proprietary plasma micromachining process technology. Acceleration sensing is based on the principle of a differential capacitance arising from acceleration-induced motion of the sense element, which further utilizes common mode cancellation to decrease errors from process variation, temperature, and environmental stress.
KXP84-2050 Datasheet
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