1. What is the working principle of acceleration sensors?
Most acceleration sensors work based on the principle of 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 the medium is called the positive piezoelectric effect.
Generally speaking, 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. However, 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.
2. Classification of acceleration sensors
1. Piezoelectric type
Piezoelectric acceleration The sensor is also called a piezoelectric accelerometer. It is also an inertial sensor. The principle of the piezoelectric acceleration sensor is to utilize the piezoelectric effect of piezoelectric ceramics or quartz crystal. When the accelerometer is vibrated, the force exerted by the mass block on the piezoelectric element also changes accordingly. When the measured vibration frequency is much lower than the natural frequency of the accelerometer, the change in force is proportional to the measured acceleration.
2. Piezoresistive type
Based on the world’s leading MEMS silicon micro-machining technology, the piezoresistive acceleration sensor has the characteristics of small size and low power consumption. , easy to integrate into various analog and digital circuits, and widely used in automobile collision experiments, test instruments, equipment vibration monitoring and other fields.
3. Capacitive type
The capacitive acceleration sensor is a pole-pitch changing capacitive sensor based on the capacitance principle. Capacitive acceleration sensor/capacitive accelerometer is a relatively common acceleration sensor. It is irreplaceable in some areas, such as airbags, mobile phones, etc. Capacitive acceleration sensors/capacitive accelerometers use microelectromechanical systems (MEMS) technology, which becomes economical in mass production, thus ensuring lower costs.
4. Servo type
Servo type accelerationThe degree sensor is a closed-loop test system with the characteristics of good dynamic performance, large dynamic range and good linearity. Its working principle is that the vibration system of the sensor consists of an “m-k” system, which is the same as a general accelerometer, but there is an electromagnetic coil connected to the mass m. When there is acceleration input on the base, the mass block deviates from the equilibrium position, and the displacement is determined by The displacement sensor detects and is amplified by the servo amplifier and converted into a current output. This current flows through the electromagnetic coil and generates an electromagnetic restoring force in the magnetic field of the permanent magnet, trying to keep the mass block at its original balanced position in the instrument housing. Therefore, The servo acceleration sensor works in a closed loop state. Due to the feedback effect, the anti-interference ability is enhanced, the measurement accuracy is improved, and the measurement range is expanded. Servo acceleration measurement technology is widely used in inertial navigation and inertial guidance systems, and is also used in high-precision vibration measurement and calibration.
3. The function of the acceleration sensor
The function of the acceleration sensor is to measure acceleration and obtain the acceleration value. Here are several common acceleration sensor application scenarios.
1. Game Control
The acceleration sensor can detect changes in inclination angles up, down, left, and right, so by tilting the handheld device forward and backward, you can control the front and back of objects in the game. The left and right direction control becomes very simple.
2. Earthquake Detection
A seismometer is a special sensor used for geological exploration and engineering measurement. It is a type of sensor that converts ground vibrations into electrical signals. The sensor can convert the ground vibration caused by seismic waves into electrical signals, convert them into binary data through an analog-to-digital converter, and perform data organization, storage, and calculation processing.
3. Car accident alarm
In modern times with the rapid development of the automobile industry, cars have become one of the main means of transportation for people to travel. However, due to traffic accidents, The number of casualties was also huge. Using high technology to save people’s lives in the information age will be one of the major research topics. The acceleration-based car accident alarm system is designed with this concept in mind. I believe that the promotion of this system will bring great benefits to the automotive industry. Come more security.
4. Pedometer function
The acceleration sensor can detect AC signals and vibrations of objects. When people walk around, they will produce certain regular vibrations. , and the acceleration sensor can detect the zero-crossing point of the vibration, thereby calculating the number of steps taken by the person or running, and thereby calculating the displacement of the person’s movement. And the calorie consumption can be calculated using a certain formula.
5. Device or terminal attitude detection
Acceleration sensors and gyroscopes are often called inertial sensors and are commonly used in various devices or terminals to implement attitude detection., motion detection, etc., which is very suitable for people who play somatosensory games. The acceleration sensor uses the acceleration of gravity and can be used to detect the tilt angle of the device. However, it will be affected by the acceleration of motion, making the tilt measurement inaccurate, so it usually needs to be compensated by a gyroscope and a magnetic sensor. At the same time, when the magnetic sensor measures the azimuth angle, it also uses the geomagnetic field. When the current in the system changes or there are magnetically conductive materials around, and when the device is tilted, the measured azimuth angle is also inaccurate. In this case, an acceleration sensor (inclination sensor) is needed. ) and gyroscope for compensation.
In addition to the above, acceleration sensors are also widely used in various fields such as handle vibration and shaking, automobile brake start detection, engineering vibration measurement, geological exploration, vibration testing and analysis, and security vibration detection. .
If the website content violates your rights, please contact us to delete it。
