It's raining heavily today

The wiper speed seems to be related to the vehicle speed

Sensor-driven wipers can detect the size of raindrops using a rain sensor, and automatically adjust the speed at which the wipers operate, thereby providing the driver with a good view and **increasing the convenience and safety of driving in rainy conditions. During operation, when the sensor detects rain falling on the windshield, it sends a signal to the wipers to start working, thereby removing the rain from the vehicle’s front windshield and ensuring clear visibility for the driver. At the same time, a command must be sent to automatically close the vehicle’s electric windows and sunroof, in order to prevent the interior of the vehicle from getting wet from rain. Working principle: The two most commonly used types of sensors at present are optical sensors and capacitive sensors. Optical sensors operate based on the principle of light refraction. In optical sensors, there is a light-emitting diode that emits a cone of light, which passes through the front windshield. When the windshield is free of rain and dry, almost all of the light is reflected onto an optical sensor ； When it rains, rainwater accumulates on the windshield, causing some of the light to be deflected. This results in a change in the total amount of light detected by the sensor, thereby detecting the presence of rain. The larger the area of reflected light that an optical sensor can capture, the more detailed the information obtained. Optical sensors are highly accurate; they can even determine with precision the number of raindrops that fall within the sensing area. Schematic diagram of capacitive sensor: It is designed based on the huge difference in dielectric constants between water and glass; the dielectric constant of water is 80, while that of glass is 2. The usual approach is to place two sets of parallel finger-shaped metal plates between the inner and outer layers of the windshield; the plates in one set intersect with each other, but do not touch the plates in the other set. When the windshield is dry, a dielectric is formed between the outer surface of the windshield and each set of finger-shaped metal plates. When the windshield becomes wet, its dielectric constant changes depending on the amount of water in contact with it. Installing the sensor on the surface of the windshield or right against its lower surface is beneficial for its operation, as such an installation allows the sensor to achieve its optimal sensitivity. Disadvantageously, installing capacitive sensors on the outer surface of the windshield creates the same problem as with resistance sensors: their metal coating is quickly scraped off the windshield due to the constant operation of the wipers.

It has to do with the intensity of the rain