The main factors that can affect UWB indoor positioning

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The main factors that can affect UWB indoor positioning [Copy link]

UWB indoor positioning, as a centimeter-level positioning technology, can theoretically achieve millimeter-level or even micron-level accuracy. However, when deploying UWB positioning systems in actual scenarios, the positioning accuracy varies greatly. Currently, the algorithms involved in UWB positioning systems mainly include TOF, TDOA, etc. Let's take a look at the main factors that can affect UWB indoor positioning.

The main factors that can affect UWB indoor positioning

1. Clock synchronization error causes errors in UWB indoor positioning accuracy

The TOA positioning algorithm requires accurate time synchronization between the target node and the reference node, and the TDOA positioning algorithm requires accurate clock synchronization between the reference nodes. Therefore, inaccurate time synchronization will cause errors in the UWB positioning system.

2. Impact of UWB base station coordinate error on positioning accuracy

In actual positioning scenarios, for example, the coordinates of the UWB tag worn by a person are relative to the coordinates of the UWB base station anchor. If the coordinates of the UWB base station itself are wrong, then the positioning data calculated by the UWB positioning engine will inevitably have errors.

3. Impact of UWB base station deployment method and number on positioning accuracy

The impact of the deployment method of UWB base stations on positioning accuracy. In the actual settlement process of positioning coordinates, the increase in the number of UWB base stations means the increase in redundant information, and rich redundant information can further reduce positioning errors. However, the UWB positioning accuracy does not increase with the increase of UWB base stations. When the number of UWB base stations increases to a certain number, the improvement of positioning accuracy by continuing to increase UWB base stations is not significant. And the increase in the number of UWB base stations means an increase in the cost of positioning hardware deployment. Therefore, how to find a balance between the number of UWB base stations and positioning accuracy, so as to reasonably deploy UWB base stations, is the focus of positioning accuracy.

4. Impact of multiple access interference on positioning accuracy

In a multi-user environment, other users' UWB signals can interfere with the target signal, thus reducing the accuracy of the estimation. One way to reduce this interference is to separate the signals from different users in time, that is, to use different time slots for transmission for different nodes.

5. Impact of human body occlusion on UWB positioning accuracy

The main component of the human body is water, which has a strong absorption effect on UWB wireless pulse signals, causing the UWB signal strength to attenuate and the ranging information to be biased, affecting the subsequent positioning accuracy.

6. The impact of multipath effect on UWB signal propagation will also cause errors in positioning accuracy

During the propagation process, the ultra-wideband UWB positioning signal will be affected by the reflection and refraction of the surrounding environment such as walls, glass, and tabletops, resulting in multipath effects. Changes in signal delay, amplitude, and phase will cause energy attenuation and a decrease in the signal-to-noise ratio, resulting in the first-arrival signal not being a direct signal, causing ranging errors and a decrease in UWB positioning accuracy.

7. Impact of UWB signal weakening when penetrating obstructions on UWB positioning accuracy

When UWB signals penetrate ordinary brick walls, the signal value will be weakened by nearly half. The change in signal transmission time caused by penetrating the wall will also affect the positioning accuracy.