Knowledge Base

The accuracy is at least 15cm (6 inch) in all directions, from the measured location. This means that the real location of the tag is within a 30 cm/12 inch diameter circle around the measured location.

Of course, our Operations team will always try to maximize accuracy. Sometimes we can achieve an accuracy as high as 5 cm / 2 inch in the center of the tracking area. If this is possible depends on the characteristics of the tracking site:

• How good is the 'line of sight' between anchors?
• Are there any blocking objects?
• Are there any flat-surfaced solid metal objects that may cause reflections?
• How good is the line of sight between tags and anchors?

In the pre-Sales process, we make sure that the site meets the requirements needed to be able to meet the accuracy claim. This includes the min and max distance between anchors. Any issue that may compromise tracking accuracy is evaluated in the pre-Sales process. 

Notes:

• There are 2 dimensions of the 'quality of location measurement'; there is accuracy and precision. The picture below illustrates how precision determines the variation (standard deviation) in location measurements for a static tag. The accuracy tells you how far the center of gravity/mean location is away from the real-world point. Both qualities determine how big the accuracy circle is.

• By nature of the triangulation-based localization method, the precision will differ across the tracking area. Learn more about the characteristics of UWB tracking precision in this article. In general, the accuracy will be best in the center of the tracking area, and gradually degrade towards the corners. Directly below the anchors, the 15cm accuracy requirement may not be met, due to the intrinsic characteristics of UWB tracking. However, in most cases, the subjects (animal or human) tend to not move all the way into a corner, especially not with the head (where the tag is normally located).
• At the moment, our accuracy claim is restricted to the static accuracy, i.e. static location measurement. In case a customer asks, we do not yet have a claim for dynamic and analysis accuracy. Of course this is derived from the static accuracy but you could measure a tag moving across a trajectory with a known distance, and then compare with the measured distance. R&D plans to come up with a claim that for example says the dynamic accuracy/distance moved is +/- x%.
• The dynamic accuracy also depends on settings that affect the track smoothing; tag sample rate, tag sleep mode settings, track smoothing and Minimal Distance Moved (MDM) filter in TrackLab. These are adjusted based on the subject type and movement characteristics.
• Some customers have also asked how we calibrate the system, and if there is a way for them to periodically re-calibrate the system (as per research procedural requirements). R&D is planning a solution for this. Ask the TrackLab PM for more details.