How the acceleration sensor works

What is an acceleration sensor? How does it work? An acceleration sensor is a test instrument used to convert the physical signal of acceleration into an electrical signal that is easy to measure. It is a commonly used testing instrument for shock and vibration measurement in many fields such as industry and national defense.

So how does the acceleration sensor work? Let’s learn it with the editor:

The sensitive element converts the acceleration signal of the measuring point into a corresponding electrical signal, enters the preamplifier circuit, improves the signal-to-noise ratio of the signal through the signal conditioning circuit, and then performs analog-to-digital conversion to obtain a digital signal, and finally sends it to the computer, which then processes the data. Storage and display.

When the sensing element moves with acceleration a, the mass block is acted upon by an inertial force opposite to the direction of acceleration, causing a deformation proportional to the acceleration a, which causes stress and strain in the cantilever beam. This deformation is felt by the diffusion resistor attached to the cantilever beam. According to the piezoresistive effect of silicon, the resistance of the diffusion resistor changes in proportion to the strain. Using this resistor as an arm of the bridge, the acceleration can be measured by measuring the change in the output voltage of the bridge.

The principle of the linear accelerometer is the principle of inertia, which is the balance of force. A (acceleration) = F (inertial force) / M (mass). We only need to measure F. How to measure F? Just use electromagnetic force to balance this force. You can get the relationship between F and current. Just use experiments to calibrate this proportional coefficient. Of course, the intermediate signal transmission, amplification, and filtering are all matters of the circuit.

Most acceleration sensors work based on the principle of the piezoelectric effect.

The so-called piezoelectric effect is "For heteropolar crystals that do not have a center of symmetry, the external force exerted on the crystal will not only deform the crystal, but also change the polarization state of the crystal and establish an electric field inside the crystal. This kind of mechanical force will The phenomenon of polarizing a medium is called the positive piezoelectric effect."

Generally, acceleration sensors take advantage of the characteristics of their internal crystal deformation caused by acceleration. Since this deformation generates a voltage, the acceleration can be converted into a voltage output simply by calculating the relationship between the generated voltage and the applied acceleration. Of course, there are many other methods to make acceleration sensors, such as piezoresistive technology, capacitance effect, thermal bubble effect, and light effect, but the most basic principle is that a certain medium is deformed due to acceleration, and the deformation is measured and used The associated circuitry converts it into a voltage output. Each technology has its own opportunities and problems.

Piezoresistive acceleration sensors are developing the fastest due to their widespread use in the automotive industry. As safety becomes more and more of a selling point for automakers, such add-on systems are becoming more common.

Piezoelectric technology is mainly used in industry to prevent machine failures. This sensor can be used to detect potential machine failures to achieve self-protection and avoid accidental injuries to workers. This sensor has the features that users, especially those in the quality industry, are pursuing. repeatability, stability and self-generation. However, in many new application fields, many users are not yet aware of the use of such sensors. It will be troublesome for sellers to venture into this untapped market because end users are not familiar with the problems and solutions caused by the use of such sensors. I don’t know much about the methods. If these problems can be solved, it will promote the faster development of piezoelectric sensors.

When using acceleration sensors, sometimes the output signal is distorted when measuring in low-frequency situations. Using various measurement and judgment methods, the cause of the fault cannot be found for a while. After analysis and summary, the main factors leading to the distortion of the measurement results are: poor low-frequency response of the system. , The low-frequency signal-to-noise ratio of the system is poor, and the external environment affects the measurement signal. Therefore, whenever there is distortion of the low-frequency measurement signal of the acceleration sensor, compare the above three points to see which factor is causing it, and solve it in a targeted manner. The above is the analysis of the acceleration sensor, I hope it can help you.