Wireless Tracking System And Method Utilizing Tags With Variable Power Level Transmissions
The present invention provides a solution to mistaken location calculations based on multipath effects. The present invention utilizes tags attached to objects that transmit signals at various power levels for reception by sensors stationed throughout a facility. Sensor readings at the various power levels are utilized to determine the location of the tagged object.
1 . A method for determining a real-time location of an object within an indoor facility, the method comprising:
calculating a plurality of preliminary locations of the object, each of the plurality of preliminary locations generated from a plurality of sensor readings set at a unique power level; and
analyzing each of the plurality of preliminary locations of the object to determine a real-time location of the object within the indoor facility.
2 . The method according to claim 1 wherein the plurality of preliminary locations ranges from two to ten, and the unique power levels range from two to ten, and each unique power level is at least 10% different than any other unique power level.
3 . The method according to claim 1 wherein analyzing each of the plurality of preliminary locations of the object to determine a real-time location of the object within the indoor facility comprises:
determining a zone within the indoor facility that contains each of the plurality of locations of the object; and
calculating the real-time location of the object from a position of a plurality of sensors within the zone utilizing a radial basis function.
4 . A system for providing real-time location information for a plurality of non-stationary objects within an indoor facility, the system comprising:
a mesh network within an indoor facility;
a plurality of tags, each of the plurality of tags attached to one of the plurality of non-stationary objects, each of the plurality of tags having a transceiver for wirelessly transmitting radiofrequency transmissions to the mesh network at least three different energy levels; and
a processing engine for processing the tag specific data at each of the three different energy levels to obtain a real-time first plurality of sensor readings for the tag at a first energy level, a real-time second plurality of sensor readings for the tag at a second energy level, and a real-time third plurality of sensor readings for the tag at a third energy level, to select a physical region within the indoor facility having sensor readings from each of the first plurality of sensor readings, second plurality of sensor readings and third plurality of sensor readings, and to calculate the position of an object from the sensor readings positioned within the selected physical region.
5 . The system according to claim 4 wherein the tag specific data comprises signal strength, link quality, time and identification of the tag.
6 . A method for determining a real-time location of an object within an indoor facility, the method comprising:
calculating a first preliminary location of the object from a first plurality of sensor readings generated at a first power level;
calculating a second preliminary location of the object from a second plurality of sensor readings generated at a second power level, the second power level less than the first power level; and
analyzing the first preliminary location of the object and the second preliminary location of the object to determine a real-time location of the object within the indoor facility.
7 . The method according to claim 6 wherein the second power level is 50% of the first power level.
8 . The method according to claim 6 wherein the first power level is 1 milli-Watt, the second power level is 0.5 milli-Watt, and third power level is 0.25 milli-Watt.
9 . The method according to claim 6 wherein analyzing the first preliminary location of the object and the second preliminary location of the object to determine a real-time location of the object within the indoor facility comprises:
determining a zone within the indoor facility that contains the first preliminary location of the object and the second preliminary location of the object; and
calculating the real-time location of the object from the position of sensors within the zone utilizing a radial basis function.
10 . The method according to claim 6 wherein the first plurality of sensor readings and the second plurality of sensor readings are obtained from a mesh network.