We're using it Multi dimensional force sensor At the same time, we often need to pay attention to it sensor For example, if a 100kg object is only placed on the sensor for 0.1s, whether the sensor can accurately measure out, this requires that the response frequency of the sensor is high enough.
Here we need to know the natural frequency of the sensor, that is, the frequency when the sensor resonates, multidimensional force sensor The internal structure can also be regarded as a vibration system. The natural frequency is the first-order vibration frequency of the system, under which the vibration amplitude is large. When the frequency of the sensor is near this frequency, the sensitivity coefficient deviation of the sensor is large. Therefore, when the frequency of the sensor is close to this value, the output signal of the sensor will be distorted, resulting in a serious decline in measurement accuracy. Therefore, in order to ensure the accuracy of measurement, we can only use the frequency band within 1 / 3 or 1 / 5 of the natural frequency of the sensor.
The natural vibration frequency of the sensor is inversely proportional to the scale and proportional to the stiffness. The resonance frequency is related to the hardness, mass and overall dimension of the metal. When it is deformed, the elastic force makes it grey. The elastic force is mainly related to the size and hardness, and the mass affects the acceleration. In the same shape, the frequency of high hardness is high, and the frequency of high quality is low.
If further consideration is made, it is stated in the basic theory of solid state physics that:
Each object is composed of N sub objects, each sub object has 6 degrees of freedom, so each object has 6N degrees of freedom. However, the natural frequency of an object varies with its degree of freedom. In general, a multi degree of freedom system has multiple natural frequencies.
The natural frequency of an object depends on its own stiffness (not strength) and has directionality, which is determined by the structure of the object.
When the object is forced to vibrate, its vibration frequency depends on the frequency of the external vibration. When the external vibration acts on the object, when the external vibration frequency is close to the natural frequency of the object, obvious vibration aggravation phenomenon will occur.
There is a simplified formula in solid state physics, t = 2 × π × SQL (M / k).
In fact, the stiffness and mass of any system are very complex, so it is difficult to calculate accurately. In most cases, measurement is used.
Therefore, the natural frequency of the sensor is mainly related to the structure and material of the sensor itself. In practical application, we must consider its own use and select the sensor with appropriate response frequency according to the demand, so as to ensure the authenticity of our experimental data.