3D localization
The system
Hardware
The localization system at hand consists of at least 4 "anchors" and a "tag".
Each device communicates and ranges with each other through an UWB (Ultra Wide Band) radio.
| Anchors | Tag | ||||
|---|---|---|---|---|---|
| a cortex-m0 processor from ST (STM32f072) | an UWB device (DWM1000) | a pressure sensor (LPS25H) | a 3.3v low noise LDO regulator (MIC5209) | a single-cell LIPO charger (MCP73831) | |
| a cortex-m3 processor from ST (STM32f103) | an UWB device (DWM1000) | a pressure sensor (LPS25H) | a high precision IMU (MPU-9250) | a 3.3v low noise LDO regulator (MIC5209) | a single-cell LIPO charger (MCP73831) |
Operation
Limitations
The system does come with a few limitations, which will be discussed below.
Line of sight (LOS)
The most important limitation is that it is very sensitive to line of sight (LOS). This means that the tag trying to localize itself, should always have pure line of sight to at least 4 anchors, which is why it is recommended to run the system with 6 or more anchors, as this would give the system redundancy. It is possible to give a clue about whether the most recent range measurement was taken in a line of sight situation or not, by looking at the quality of the measurement. This quality is a combination of the received power level and the first path power level, and is discussed further in
% ADD link to discussion about LOS! DW1000 User manual, p. 45
