Hybrid positioning method, electronic apparatus and computer-readable recording medium thereof

1. A hybrid positioning method for an electronic apparatus configured as a wearable mobile device having an absolute positioning device, a relative positioning device and a display device, the absolute positioning device having a GPS receiver and being configured to collect geographical location readings of the electronic device, the relative positioning device being configured to collect sensor readings associated with movement of the electronic apparatus, the method comprising:

obtaining initial location information of the electronic apparatus;

computing initial moving information of the electronic apparatus based upon the sensor readings;

computing estimated location information based on the initial moving information and the initial location information, wherein the estimated location information comprises an estimate location and an estimated heading;

acquiring geographical location readings responsive a location update condition being satisfied, wherein the geographical location readings comprise a sequence of geographical location readings;

generating reference location information based on the geographical location readings acquired;

calculating a variance among the sequence of geographical location readings;

storing a last one of the sequence of geographical location readings as a reference location if the variance is smaller than a variance threshold;

comparing at least two of the geographical location readings to obtain a reference heading;

comparing the estimated location information with the reference location information to obtain a deviation information, wherein the deviation information comprises a location offset and a heading deviation, which are calculated by comparing estimated location and reference location, and comparing estimated heading with reference heading, respectively;

computing a calibrated moving information based on the estimated location information and the deviation information;

computing a calibrated location information based on the deviation information, calibrated moving information and the estimated location information; and

displaying the calibrated location information with the display device.

2. The method of claim 1 , further comprising:

comparing the initial location information and the estimated location information;

computing a difference between the initial location information and the estimated location information;

determining whether the location update condition is satisfied based on the difference;

wherein the location update condition is satisfied when at least one of: a distance value, distance-turn values, or a time value corresponds to a distance threshold, a distance-turn threshold, or a time threshold, respectively.

3. The method of claim 2 , wherein:

the distance-turn threshold corresponds to a distance component and a turn angle; and

the distance threshold, which corresponds to a straight line distance, is longer than the distance component of the distance-turn threshold.

4. The method of claim 2 , wherein the time threshold corresponds to a time duration beginning when the geographical location readings were last updated.

5. The method of claim 1 , wherein the initial moving information comprises an initial moving distance and an initial heading change, the calibrated moving information comprises a smooth amount, a smooth count and a smooth angle, the calibrated location information comprises a calibrated location and a calibrated heading and the method further comprises:

calculating a smooth count based on the location offset;

calculating a smooth angle based on the deviation angle and the smooth count;

computing the calibrated heading based on the smooth angle and the estimated heading;

computing the estimated location based on the initial location and the calibrated heading;

calculating a smooth amount based on the deviation information and the smooth count; and

computing the calibrated location based on the smooth amount and the estimated location.

6. The method of claim 5 , wherein the geographical location readings comprise a sequence of location readings, and the method further comprises:

selecting at least two of the sequence of geographical location readings;

computing at least two previous estimated locations, wherein each of the at least two of the sequence of location readings synchronize with the at least two previous estimated locations;

calculating a length factor by comparing the at least two previous estimated locations and the selected at least two of the sequence of location readings; and

computing the calibrated moving information based on the length factor.

7. The method of claim 5 , further comprising forming a traveling trace based on a sequence of the calibrated location.

8. The method of claim 1 , further comprising:

obtaining a reference geographical coordinate according to the reference location; and

transforming the calibrated location to calibrated geographical longitude and latitude based on the reference geographical coordinate.

9. The method of claim 1 , wherein:

computing calibrated location information further comprises determining whether the reference location is behind the estimated location in view of the estimated heading; and

if the reference location is behind the estimated location in view of the estimated heading, applying to the estimate location a component of the location offset, which is a difference between the estimated location and the reference location, with the component being orthogonal to a direction of the estimated heading.

10. The method of claim 1 , further comprising calculating an error value based on accuracy of the geographical location readings, wherein the accuracy is determined based on readings from the GPS receiver that receives GPS satellite radio signals from a GPS satellite constellation via antennas.

11. The method of claim 1 , wherein displaying comprises displaying a traveling trace based on a sequence of the calibrated location information.