Methods and devices for position determination using regional minimal residual estimation

A computer-implemented method for determining user position, implemented in a handheld user computing device programmed to perform the method comprising:

• receiving, in the handheld user computing device, a starting user position estimate from an outside initialization source;
• receiving, in the handheld user computing device, a plurality of Wi-Fi signals from a plurality of Wi-Fi access points, each of the plurality of Wi-Fi signals being associated with one of the plurality of Wi-Fi access points;
• determining, in the handheld user computing device, a plurality of signal strength measurements, each of the signal strength measurements being associated with one of the plurality of Wi-Fi signals;
• determining, in the handheld user computing device, a plurality of access point locations, each of the access point locations being associated with one of the plurality of Wi-Fi access points;
• determining, in the handheld user device, a total solution residual across a two-dimensional solution grid using the starting user position and the plurality of signal strength measurements and the plurality of access point locations, wherein determining the total solution residual comprises determining a position residual for each point in the two-dimensional search grid, the starting user position estimate being used to determine a solution region for the two-dimensional solution grid;
• and
• determining, in the handheld user device, an estimated user position based on the minimized position residual of the total solution residual within the solution region;
• wherein determining the estimated user position includes solving local minima points versus the absolute minima of a line of sight residuals.

A handheld user computing device specifically programmed by executable software code to determine a user position, the hand-held computing device comprising:

• a physical sensor configured to determine a plurality of signal strength measurements in response to plurality of signals from a plurality of access points;
• an inertial navigation system or inertial sensing system;
• a memory configured to store executable software;
• and
• a processor coupled to the physical sensor and the memory, wherein the processor is programmed by the executable software to:
• receive a starting user position estimate from an outside initialization source;
• receive a plurality of Wi-Fi signals from a plurality of Wi-Fi access points, each of the plurality of Wi-Fi signals being associated with one of the plurality of Wi-Fi access points;
• determine a plurality of signal strength measurements, each of the signal strength measurements being associated with one of the plurality of Wi-Fi signals;
• determine a plurality of access point locations, each of the access point locations being associated with one of the plurality of Wi-Fi access points;
• determine a total solution residual across a two-dimensional solution grid using the starting user position estimate and the plurality of signal strength measurements and the plurality of access point locations, wherein determining the total solution residual comprises determining a position residual for each point in the two-dimensional search grid, the starting user position estimate being used to determine a solution region for the two-dimensional solution grid;
• determine an estimated user position based on the minimized position residual of the total solution residual within the solution region;
• and
• using the inertial navigation system or inertial sensing system to only search for regions of convergence near a most recent estimate of the user position.