In order to explain the working principle of the force sensor, we first need to answer the following questions: Most force sensors are equipped with strain gauges. How does the strain gauge work?
Let us briefly understand the strain gauge. The strain gauge is firmly attached to the substrate as an electrical conductor. When the substrate is stretched, the strain gauge will become longer. Conversely, when compressed, the strain gauge will shorten, resulting in strain. The resistance of the instrument changes, which is the principle of strain measurement, and the strain resistance is determined by the transformation of the strain resistance.
In order to manufacture the force sensor, in addition to the strain gauge, an elastic body is needed. The strain gauge will be firmly connected to the elastic body. We use the simplest elastic body-a steel cylinder for illustration.
(1) If the strain gauge is compressed, its resistance (Ω) will decrease, and if it is stretched, the resistance will increase.
The strain gauge constitutes the Wheatstone bridge. The Wheatstone bridge will not be explained in detail here. Those who are interested can Baidu on their own. Since the strain gauge is firmly installed on the elastic body, the strain gauge will produce the same deformation as the elastic body. This causes a change in resistance. The deformation information is converted into an electrical signal through a Wheatstone bridge. In this way, the force on the strain gauge can be calculated. This is how the force sensor works.
So what are the differences between load cells and force sensors?
First of all, in terms of nature and principle, they seem to be very similar. A load cell measures the mass or weight of an object, while the measuring force of a force sensor is N or Newton. Each Newton is approximately equal to 100 grams. Let's analyze the two together. difference between!
The load cell is only used to measure the weight of the object, and only measures the direction of the gravity field, that is, it can only measure the force perpendicular to the ground, and the weight will always be greater than zero. If the container is placed under the load cell, then Will not produce weight in the opposite direction, and the force sensor is different, it can be tilted in various directions of pressure angle.
The load cell is produced in the factory and then needs to be calibrated in the field. The force sensor is calibrated in the factory immediately after production. Therefore, it is necessary to ensure that the measured value is the same after the sensor is removed and installed. Therefore, the load cell has a specific strength The sensor has a more robust structure to ensure the accuracy of the measured value under various changing conditions.
The standards for load cells and force sensors are different. Load cells are usually commercial-scale standards, while force sensors need to meet the VDI2635 or ISO376 standards. Among these standards, the accuracy of the sensor is the most important factor.