At present, most ultrasonic positioning methods adopt reflective ranging. The system consists of a main rangefinder and several electronic tags. The main range finder can be placed on the mobile robot, and each electronic tag is placed in a fixed position in the indoor space. The positioning process is as follows: first, the upper computer sends signals with the same frequency to each electronic tag, and then the electronic tag receives them, reflects them and transmits them to the main range finder, so as to determine the distance between each electronic tag and the main range finder and get the positioning coordinates.

infrared technique

Infrared ray is an electromagnetic wave with a wavelength between radio wave and visible light wave. A typical infrared indoor positioning system, Activebadges, attaches an electronic ID to the measured object, periodically sends the unique ID of the object to the indoor fixed infrared receiver through an infrared transmitter, and then the receiver transmits the data to the database through a wired network. This positioning technology consumes a lot of power and is often blocked by indoor walls or objects, so it is not practical.

Ultra-wideband technology

Ultra-wideband technology is a new wireless technology in recent years. At present, countries including the United States, Japan and Canada are studying this technology, which has a good prospect in the field of wireless indoor positioning. UWB technology is a wireless technology with high transmission rate (up to 1000Mbps), low transmission power and strong penetration ability. It is based on extremely narrow pulses and has no carrier wave. It is these advantages that make it get more accurate results in the field of indoor positioning.

Radio frequency identification technology

Radio frequency positioning technology is very convenient to implement, the system is less disturbed by the environment, and the electronic tag information can be edited and rewritten flexibly.