Difference Between An Accelerometer And A Gyroscope

Accelerometer and gyroscope are two kinds of sensors commonly used in vibration monitoring of structures. They all measure changes in vibration or displacement by sensing changes in an object’s acceleration or angular velocity. But there are some differences in how they work and how they are applied. The following will be a detailed introduction to the role and differences between accelerometers and gyroscopes.

The function and principle of accelerometer

The accelerometer is used to measure acceleration. A triaxial accelerometer can be used to measure the motion of a fixed platform relative to the earth’s surface, but once the platform moves, the situation becomes more complex.  For example, the ER-3QA-02E is a high-performance three-axis accelerometer with digital output, high precision installation error, temperature compensation, and low power consumption.If the platform is free falling, the accelerometer measured the acceleration value is zero. If the platform is moving in a certain direction, the acceleration values of each axis will contain the acceleration value generated by gravity, so that the true acceleration value cannot be obtained. For example, the triaxial accelerometer mounted on the 60-degree roll Angle plane will measure the vertical acceleration value of 2G, whereas in fact the plane’s surface is about 60 degrees. Therefore, using the accelerometer alone cannot keep the aircraft in a fixed course.

The function and principle of gyroscope

Gyroscope measures the rate of rotation of the body around an axis. When the gyroscope is used to measure the rotation Angle of the aircraft’s body axis, if the plane is rotating, the measured value is non-zero, and the value of the measurement is zero when the plane is not rotating. Therefore, the angular velocity value of the gyroscope measured at the 60-degree roll Angle is zero, and the angular rate is zero when the plane is flying in a straight line. The current roll Angle can be estimated by the time integral of the angular velocity value, provided there is no error accumulation. Gyroscope to measure the value of the drift with time, after a few minutes or a few seconds will be the additional error accumulation, and eventually lead to the current relative horizontal roll Angle to the plane completely wrong cognition. Therefore, the use of gyroscopes alone cannot maintain a particular course of the aircraft.

The difference between accelerometers and gyroscopes

Accelerometers and gyroscopes are both sensors used to sense changes in vibration or displacement of structures, but there are some important differences between them.

1. Different measurement methods

The accelerometer mainly measures the linear acceleration of the object, while the gyroscope mainly measures the angular acceleration and angular velocity of the object. Their measurement methods are different, so they are suitable for different vibration test occasions. The high performance quartz flexible accelerometer represented by ER-QA-03A adopts high quality quartz crystal to achieve high precision acceleration measurement and has extremely high reliability and stability. Its special flexible construction enables it to adapt to high acceleration applications under various environmental conditions, such as high temperature, high pressure and high vibration environments.

2. Different measurement directions

The accelerometer mainly measures the vibration acceleration of the structure in the x, y and z directions, while the gyroscope mainly measures the angular velocity of the object in the x, y and z axes. Therefore, they are suitable for vibration tests that are not coaxial upwards.

3. Different application fields

Accelerometers are mainly used in the field of structural vibration testing, while gyroscopes can be used in a wide range of object motion testing fields, such as drones, aerospace and so on.
In summary, accelerometers and gyroscopes are commonly used sensors for vibration testing of structures and motion testing of objects. They have their own characteristics and application range. Accelerometers are generally more commonly used than gyroscopes in vibration measurement applications, but in the measurement of angular displacement and velocity of objects, gyroscopes are more suitable.

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