It is already proven that X-Y coordinates can be obtained from the UWB RTLS system with sub-meter accuracy even in harsh industrial environments. Nevertheless, estimation of Z coordinate is still challenging and always needs to be considered based on given use-case.
The X-Y coordinates are set during Setting up the Sensmap. The RTLS System considers a Tag Z coordinate in the same height Anchors in default. It could lead to inaccuracy of the localization. To improve the accuracy, the Tag height has to be set → we call it Z-Axis compensation.
This parameter can be used to further optimize the precision and performance of the system for 2D calculation, which is the most common scenario. When the height difference between Tags and Anchors is more than a few meters (>2m). The value should be set to the usual height of Tag above the ground (e.g. if a person is wearing a tag around his neck on a strap, the height is approximately 1.5 m). The next step is to set height coordinates of all Anchors – it is the height measured above the ground.
To set up Z-Axis Compensation, you go to RTLS Manager section RTLS Server Setting→Position Adjustment:
Keep in mind that the Z-Axis compensation is useful for applications where tags are approximately at the same height (± 0.5m).
Here you can see differences between Z-Axis compensation in default and Z-Axis Compensation set as 1.2 meters:
Note: If only 3 anchors are used for position calculation, the Z-Axis Compensation optimization function will not be used for this calculated position (see Position Adjustment). In some cases, this results in a significant difference in the calculated position compared to the position (previous or next) calculated by the 4 anchors (i.e. such a situation may be reflected in positional data as a significant jump between successive positions).