The automatic control system can complete a certain task in the case of people who do not participate in people. The key is the introduction of feedback, and feedback is actually the output or state of the system, plus the input of the system and the input of the system to the system. The output status of the system is actually a variety of physical quantities, and they are voltages, and some are traffic, speed, etc. These amounts are often different from the system of the system, and the range of the value is different. So you can't use it directly to your input, you need to measure and transform. The sensor is this role, it is like the eyes and skin of the control system, and the various changes in the control system, and the other parts of the system work together to complete the control task. Humanity must obtain information from the outside world, must be used in the sensory organs. But people's feelings are not universal. To get more information, further study natural phenomena and manufacturing labor tools, people's senses are very unsure enough. As a tool that replaces people's sensory, the history of sensors is older than modern scientific. Baiping as a tool of weight is used in ancient Egypt, and it is always used in the current. Temperature measurements in the sixteenth century have appeared in the sixteenth century. Sensor based on electrical basic principles is based on modern electromagnetic development, but with the improvement of active components such as vacuum tubes and semiconductors, this type of sensor has developed rapidly. The sensor is mostly means of electrical signal output. Sensor can be used to measure various physical quantities. Depending on the measured physical quantity, the sensor can be divided into a variety of types of temperature sensors, flow sensors, and pressure sensors. However, all sensor works are based on various physical laws. If new phenomena or in certain substances, these phenomena and effects can be used to develop sensors. Physical phenomena and effects that are often used to make sensors are Hall effect, Doppler effect, dielectric resistance effect, strain effect, etc. However, it is not possible to use all the sensors that can be used because the sensor needs to meet the reliability requirements, in order to obtain the measured raw information from the output signal of the sensor, if the sensor is unstable, the same input signal, its output signal It is not the same, the sensor will give the error output signal to make the sensor fail. Just like a human nose is adapted to the environment, it will lose sensitivity for the feeling of odor. The sensor is like the eyes of the automatic control system, like the nose, the ear, plays an important use for the performance of a control system. Reliable, sensitive sensor is the premise of automatic control system work. Just like the blind people who are blind, it is impossible to get what they have to take. If the control system's sensor part does not work properly, the automatic control system has a way to replace people to complete the work.
