IR (Infrared Radiation, short for infrared), the IR sensor is a non-contact sensor that can detect the infrared radiation of an object, and determine the position and distance of the object by reflecting light waves. They are generally faster and more accurate than ultrasonic sensors, but require some visibility to measure distance and cannot measure transparent objects. In addition, IR sensors are very sensitive to the temperature and light conditions of the environment.
Ultrasonic sensors use an ultrasonic wave above 20kHz that cannot be heard by the human ear. According to the frequency band, ultrasonic waves can propagate in any medium such as gas, liquid, solid, etc., but the propagation speed depends on the acoustic impedance of the medium. Ultrasonic sensors can measure transparent objects and non-metallic objects, and can also be used in low-light environments. In addition, the ultrasonic sensor has strong anti-interference for the environment in which it is used, and is not affected by dust, dirt or high humidity levels, and can be used in any lighting environment.
To sum up, ultrasonic sensors are largely insensitive to obstructive factors such as: light, dust, smoke, mist, steam, lint. But ultrasound is not as good as infrared for defining the edges of an area. In addition, infrared sensors cannot work in dark environments, while ultrasonic sensors can. Therefore, which sensor to choose depends on the specific application scenario and needs. For scenarios that require high-precision measurements, IR sensors may be more suitable. For scenes that need to detect transparent or non-metallic objects, or scenes that are used in noisy environments, ultrasonic sensors are relatively better.
