FR2975191A1 - METHOD OF GEOLOCATION IN A PERTURB RADIOFREQUENCY TRANSMISSION ENVIRONMENT - Google Patents

Abstract

The present invention relates to a method of geolocation in a disturbed radiofrequency transmission environment, for the estimation of a position on a predefined course, comprising: a step of recording during a course of at least one temporal sequence of captured time-stamped signals; one or more steps of refining said sequence of time-stamped signals, and at least one step of predicting a given position by the processing of said refined time-stamped signal sequence. The invention also relates to an equipment and a computer program for implementing the geolocation method.

Description

Field of the Invention The present invention relates to the field of geolocation, and the determination of a position on a given course. It relates more particularly to geolocation in a disturbed radiofrequency transmission environment, for example for determining the position in an underground network such as the subway or a tunnel, or a subterranean gallery.

STATE OF THE ART In the state of the art, US patent application US60 / 702,285 describes a system for guiding and controlling a mining machine in a tunnel or an underground passage. In this solution, the positioning is determined by comparison with a recorded RF signal card. US5999865 or US6694233 patents provide similar solutions. Also known is patent US6028550 describing a guidance system based on the analysis of the electromagnetic signature of a cell to determine the position. PCT Patent Application WO2006 / 007442 is still known. This document relates to methods, radios, associated components, and other devices for locating a geographic location of a radio receiver. A radio signature comprises a plurality of measured signal qualities that collectively represent a frequency spectrum. Each measured signal quality among said plurality of qualities corresponds to a portion of the frequency spectrum. The current radio signature is compared to a plurality of radio reference signatures. Each reference radio signature among said plurality of reference radio signatures is associated with a world position. When the comparison makes it possible to identify a unique match between the current radio signature and a reference radio signature among the plurality of radio reference signatures, the radio receiver is made to be located at the world position associated with the reference radio signature.

Disadvantages of prior art

The solutions of the prior art have the disadvantage of being dependent on the quality of the signal picked up at each point. The localization is done statically, by the local analysis of the signals, either to determine the position at the time of the analysis, or to restore the trajectory of the cells traversed by a mobile machine. If the signal is disturbed at the place of measurement, the information will be unusable and will not allow a satisfactory location. Optionally, some solutions of the prior art provide treatments to improve the quality of the local signal.

Solutions proposed by the invention.

The present invention aims to overcome the drawbacks of the prior art by proposing a solution making the process insensitive to occasional disturbances of the signals received. In particular, the invention proposes a solution that is not sensitive to location errors, since it does not take into account an estimated absolute position, but a position on a determined path or even constraint. To this end, the invention relates, in its most general sense, to a geolocation method in a disturbed radiofrequency transmission environment, for estimating a position on a predefined path, including a step of recording during least one path a time sequence of timestamped signal signals, - one or more refinement steps of said sequence of time stamped signals, and - at least one step of predicting a given position by the processing of said refined timestamped signal sequence. According to a first variant, said received signals 10 are radio frequency signals. According to a second variant, said captured signals are sound signals. According to a third variant, said received signals are light signals. According to a fourth variant, said sensed signals come from a source of mechanical vibration. According to a fifth variant, said captured signals are variations of gravity. According to a sixth variant, said sensed signals are variations of the magnetic field. According to a seventh variant, said captured signals are particular information provided by mobile equipment. The particularity of this information consists of a value that varies according to the position of the user. An example of such user location dependent information could be an estimate, even very imprecise, made by mobile equipment from triangulation on geolocated data. Advantageously, the method according to the invention further comprises registration steps from geolocation data: from an external cartographic source. - associated with radiofrequency signals. - associated with the sound signals. 35 - associated with the light signals. associated with signals from a source of mechanical vibration. - from a gravity analysis. - from an analysis of the magnetic field. - from an analysis of the information, dependent on the position of the user, provided by a mobile equipment. Preferably, the resetting mode is controlled as a function, on the one hand, of the accuracy of each of the available resetting modes and, on the other hand, of the energy cost of each of said available resetting modes. Preferably, the method according to the invention further comprises a step of recording at least one reference location, and steps of determining the temporal position with respect to said reference location. According to a particular embodiment, the method further comprises steps of exchanges with a server recording the geolocation data from a plurality of equipment, and transmitting sets of geolocation data to the equipment of a new user. Advantageously, these geolocation data are grouped according to their belonging to a trajectory shared by several users.

Preferably, the geolocation data are signed at the time of their local or remote recording.

The invention also relates to mobile equipment comprising at least one clock and at least one sensor of a signal and processing means for implementing the method according to the invention. The invention also relates to a downloadable computer program for its installation and its execution on mobile equipment, characterized in that it is configured for the implementation of the method according to the invention.

Detailed description of an exemplary embodiment of the invention

The invention will be better understood on reading the detailed description which follows, relating to a nonlimiting example of embodiment with reference to the appended drawings in which: FIG. 1 represents a schematic view of a process for acquiring signals on a route FIG. 2 represents a schematic view of the structure of the time-stamped sequences; FIG. 3 represents a functional diagram of a system for implementing the method according to the invention; FIG. 4 represents a schematic view of the network reconstitution; of public transport by assembling 20 sequences from different users

Figure 1 shows a schematic view of data acquisition.

The acquisition equipment is constituted by a portable equipment, for example a mobile tablet or a mobile phone, having capabilities for installing a software application.

The user moves on a defined path, for example a metro, bus, tram or train line. During the movement, it detects signals Signall, Signal2, Signal3 corresponding to remarkable points of the paths, which can be associated with time positions tl, t2, t3 35 of the path path. These positions are associated with delays - 6 Delay, Delay2, Delay3 corresponding to the time delays between the time positions t1, t2, t3 and the estimated time of attaining the reference location.

The detection of the signals is carried out by the sensors available on the equipment, and concerns, for example, the capture of the electromagnetic signals, and / or sound and / or light signals, or even magnetic signals when the equipment comprises or is associated with a signal. Magnetosensitive sensor. This last solution makes it possible to take into account the slight variations of the magnetic field produced by rocks, when the path is carried out in a gallery, for example by a speleologist or a miner. These signals are recorded in real time, at a determined acquisition frequency or periodically, or by detecting a variation of the signal considered. The signal data is recorded in time data, for example the system time. data are, in the example described, the location of the transmitting antenna of the signal is a GPS-type signal. This data is the telephony or WIFI part of the equipment, which natively comprises means of analyzing the frame of the detected RF signals and of processing for extracting from a local table the identifier and the position of the transmitting antenna of the equipment. signal detected. The temporal concordance of at least two signals recorded during a previous trip makes it possible to predict the approach of the reference location. The detection will generally be interrupted in certain parts of the route. This is nonetheless affecting the process. The recording of the time-stamped sequence simply requires the recording of a series of points along the route. correlation a BTS, where provided by 20 - 7 Another important data concerns the recording of a reference location, the approach of which will be later to be predicted, even when no signal is available at this point .

The indication of the reference location or the temporal distance with respect to this reference location will be obtained by extrapolation of the position at the given instant with respect to the previously recorded sequence. When the user travels several times the same path, the data acquired during a new displacement are compared with those previously recorded. In case of discrepancy, a treatment will assign a variable degree of confidence according to said discrepancy. This degree of confidence will be taken into account in weighting the estimated treatments. These data may also be time stamped to take into account their periodic variations. This is for example data present only certain hours of the day or certain days of the week.

Figure 3 shows a block diagram of the invention. The action sequence is as follows: - creation of a reference path, by a first step of recording the characteristic signals picked up during the traffic on the reference path. The user defines a reference location which he wishes to be informed later, during a journey of the same path. - The initial sequence of time stamped signals is recorded to enable its operation during the next runs - the computer makes an estimate of the reached or the approach of the previously defined reference location, by comparing the sequence of detected signals with the initial sequence of timestamped signals previously recorded, and triggers an action such as the emission of a sound or vibratory action during the estimated approach of the reference location - furthermore, the computer proceeds a refinement of the sequence of time stamped signals.

FIG. 4 represents a schematic view of a variant in which several users use the estimation method on the same path. In this case, the equipment, for example the cellular telephones comprising the means for implementing the invention periodically exchange the time-stamped sequences and locally perform incremental refinements from the detected signals as well as from time-stamped sequences originating from other users making the same journey.

For this purpose, the time-stamped sequences include an identification label for the route and the place of reference.

Claims (1)

CLAIMS 1 - Geolocation method in a disturbed radiofrequency transmission environment, for the estimation of a position on a predefined course, comprising a step of recording during a course a time sequence received signals stamped, one or more stages refining said sequence of time-stamped signals, consisting of comparing the data acquired during a new displacement with those previously recorded, and, in the event of a discrepancy, performing a process to assign a variable degree of confidence according to said discrepancy, for weighting the estimated treatments and - at least one step of predicting a given position by the processing of said refined timestamped signal sequence. A geolocation method according to claim 1 characterized in that said picked up signals are radio frequency signals. 3 Geolocation method according to claim 1 characterized in that said captured signals 30 are sound signals. 4 - Geolocation method according to claim 1 characterized in that said captured signals are light signals. The method of geolocation according to claim 1 characterized in that said sensed signals are derived from a source of mechanical vibration. 5 6 Geolocation method according to claim 1 characterized in that said captured signals are a variation of gravity. 7 Geolocation method according to claim 1 characterized in that said sensed signals are a variation of the magnetic field. 8 - Geolocation method according to claim 1 characterized in that said sensed signals are particular information provided by a mobile equipment. The particularity of this information consists of a value that varies according to the position of the user. 9 - A method of geolocation according to claim 1 characterized in that it further comprises resetting steps from geolocation data from an external map source. - Geolocation method according to claim 1 characterized in that it further comprises resetting steps from geolocation data from signals corresponding to claims 2 to 8. 11 - Geolocation method according to claim 9 or 10, characterized in that the resetting step is controlled as a function, on the one hand, of the accuracy of each of the available resetting steps and, on the other hand, of the energy cost of each of said available resetting steps. 35- 11 - 12 - Geolocation method according to any one of the preceding claims characterized in that it further comprises a step of recording at least one reference location, and steps of determining the time position by report to said reference place. 13 - Geolocation method according to any one of the preceding claims, characterized in that it further comprises steps of exchanges with a server recording the geolocation data from a plurality of equipment, and transmitting data sets geolocation to the equipment of a new user. 14 - Geolocation method according to the preceding claim characterized in that the geolocation data are grouped according to their membership in a path shared by several users. 15 - Geolocation method according to any one of the preceding claims, characterized in that the geolocation data are signed at the time of their local or remote registration. 16 - Mobile equipment comprising at least one clock and at least one sensor of a signal and processing means for carrying out the method according to at least one of the preceding claims. 17 - downloadable computer program for its installation and its execution on mobile equipment, characterized in that it is configured for the implementation of the method according to at least one of claims 1 to 10.