Local positioning system

A local positioning system comprising:

• a plurality of anchors placed within a facility;
• three or more calibration tags temporarily placed at respective predetermined positions within the facility;
• and
• a computing device for:
• instructing the plurality of anchors and the plurality of calibration tags to measure respective distances between each anchor of the plurality of anchors and at least three of the three or more calibration tags;
• calculating a respective calculated location of each of the plurality of anchors based on the predetermined positions of the plurality of calibration tags and the measured distances;
• and
• determining a position of a first movable tag based on respective distances between at least some of the plurality of anchors and the first movable tag and the respective calculated locations of the at least some of the plurality of anchors.

Apparatus comprising a non-volatile machine-readable medium storing a program having instructions which when executed by a computing device will cause the computing device to:

• communicate with a plurality of anchors within a facility;
• communicate with three or more calibration tags placed at respective predetermined positions within the facility;
• instruct the plurality of anchors and the plurality of calibration tags to measure respective distances between each anchor of the plurality of anchors and at least three of the three or more calibration tags;
• calculate a respective calculated location of each of the plurality of anchors based on the predetermined positions of the plurality of calibration tags and the measured distances;
• and
• determine a position of a first movable tag based on respective distances between at least some of the plurality of anchors and the first movable tag and the respective calculated locations of the at least some of the plurality of anchors.