Location finding apparatus and associated methods

摘要

A portable device uses particle filtering techniques for tracking the location of a user carrying the device. The portable device generates a particle set comprising a plurality of particles each particle representing a respective estimate of a candidate state of the portable device, wherein the estimated candidate state comprises an estimated position of the portable device. Movement of the portable device is detected and analysed to estimate distance travelled by the device and to determine an estimated direction of movement of the device and the particle set is updated to reflect an estimated change in position represented by the estimated distance travelled by the device, and the estimated direction of movement of the device. Generation of the particles may take into account estimated errors associated with the movement of the device, mapping data that suggested an estimated movement is unlikely to reflect real movement, or estimate step length of a user.