MEMS inertial measurement unit talks about accelerometer
- 2019-05-16-

Accelerometer A meter that measures acceleration. MEMS inertial measurement unit acceleration measurement is an important topic proposed by engineering technology. When an object has a large acceleration, the object and the instruments it carries and other objects without relative acceleration are subjected to a force that produces the same large acceleration, that is, a dynamic load. To know the dynamic load, the acceleration is measured. Secondly, to know the spatial position of each instantaneous aircraft, rocket and ship, the acceleration can be continuously measured by inertial navigation (see the gyro platform inertial navigation system), and then the integral component is used to obtain the velocity component, and the integral is again obtained to obtain the position in one direction. The coordinate signal, and the instrumental measurements in the three coordinate directions synthesize the motion curve and give the spatial position of each moment the aircraft is located. As in some control systems, the acceleration signal is often required as part of the information required to generate the control, and the problem of continuously measuring the acceleration also occurs here. A device that can continuously give an acceleration signal is called an acceleration sensor.

The components of common accelerometers are as follows: the outer casing (attached to the object to be tested), the reference mass, the sensitive components, the signal output, and so on. Accelerometers require a certain range and accuracy, sensitivity, etc. These requirements are often contradictory to some extent. Accelerometers based on different principles have different ranges (from a few g to hundreds of thousands of g ), and their sensitivity to the frequency of the abrupt acceleration varies. The common accelerometers are based on the following principles: (1) The reference mass is connected to the housing by a spring (see figure), and the relative displacement of the housing reflects the magnitude of the acceleration component. This signal is output by the potentiometer with a voltage; 2 Reference The mass is fixed by the elastic thin rod and the shell, the dynamic load caused by the acceleration deforms the rod, and the deformation is induced by the strain resistance wire. The output is proportional to the electrical signal of the acceleration disc size; 3 the reference mass passes through the piezoelectric element Attached to the housing, the dynamic load of the mass exerts pressure on the piezoelectric element, and the piezoelectric element outputs an electrical signal proportional to the pressure, ie the acceleration component: 4 the reference mass is connected by the spring to the housing, placed inside the coil, reflecting the acceleration component The displacement of the size changes the inductance of the coil, thereby outputting an electrical signal proportional to the acceleration. In addition, there are servo type accelerometers, in which a feedback loop is introduced to improve the accuracy of the measurement. In order to measure the acceleration vector in plane or space, two or three accelerometers are required, one for each acceleration component.

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