FR2609812A1 - Method and device for locating and identifying mobile elements - Google Patents

Abstract

Method and device permitting the simultaneous location and identification of mobile equipment. Beacons 1 which can easily be implanted in the road communicate by radio or infra-red means with other mobile beacons 2 fixed, for example, under vehicles. Application to the deployment of fleets of vehicles (police, transport systems, firecrews, ...), to guidance by map, to automatic road tolls, etc.

Description

The present invention relates to a method for locating mobile elements (pedestrians, vehicles, robots, etc.) by radio or infrared.

The invention also relates to a device for implementing this method.

Many localization systems already exist: by satellites (not usable in real time), by transmitting beacons (for certain pre-determined and very limited applications), by passing over loops (on reserved lanes), ... There is no There is currently no system allowing the use of a simple and inexpensive infrastructure. However, it appears essential in the future to inform, for example, future on-board computers of vehicles (management of route plans), central offices (fleet of vehicles, on-call staff, etc.), centers automatic payment (automatic toll). Finally, the different types of existing beacons require an infrastructure (source of electrical energy, very precise positioning of the microwave cones opposite, ...) and operate unilaterally (indication at vehicle from where it is OR identification of a vehicle to a beacon).

Figures 1 and 2 show the conventional systems:
Figure 1: identification system
Figure 2: location system
In a traditional identification system (fig. 1) the mobile equipment (2) is only equipped with a transmitter (3), while the fixed equipment (1) is only equipped with a receiver ( 4),
In a traditional location system (fig. 2), the fixed equipment (1) is only equipped with a transmitter (3) permanently or optionally triggered by passing the mobile (2) over a buried loop (5) , while the mobile equipment (2) is only equipped with a receiver (4) itself connected to external equipment (@)
The present invention aims to provide a telecommunication method and device which allow location / identification reversibility as well as the establishment of an infrastructure usable by multiple users (fig. 3).

This result is obtained, thanks to the invention, by automatically carrying out the following operations:
a.- identification equipment (2) (always assumed to be mobi
the) cyclically sends a message (7) allowing
identify it.

b.- reception of this message (7) by the equipment (1)
location (assumed to be fixed) causes sending by the same
equipment of a location message (8)
c.- according to a preferred embodiment of the method, this response,
when correctly received by the identi equipment
fication, inhibits it for a preset time, allows
both the interrogation by other identification equipment
This procedure is summarized in Figure 4. It should be noted that only a simple clue in the message distinguishes between identification and location messages.

According to an advantageous embodiment of the process, and to avoid collisions, transmissions can take place in simplex mode (only one frequency) and the emission of identification equipment (7) can be prohibited when this frequency is already occupied by another identification equipment, as shown in figure 5. It should be noted that in addition to this - it is not the reception of a location (8) by the identification equipment which inhibits its emission, but the correlation between the end of this transmission (α) and the reception (ss) of the corresponding location (constant time).

This case being very common in simplex mode, it is very important to plan it to allow a correct follow-up of identifications (fig. 4 to 7). In addition, data filtering (identification or location) may be provided so that the same information received is only sent to wired external equipment once (9).

According to a second aspect of the invention, the infrastructure described above can be used to define a mesh network, centralized or not (by wire or wireless link, ...) in whole or in part, more or less dense depending on use envisaged (city or country, ...), taking as base benchmarks the IGN type plan counts (plots, ...). In the same way, we can also make the meshed infrastructure manager of vehicle identifications (reverse method to that explained above): this can allow for example the tracking of a vehicle in real time, manage automatic tolls,.

The device advantageously includes the following two types of equipment:
- location beacons (1) (fixed)
- identification tags (2) (mobile) it should be noted that the electronics (technology) composing these tags is the same for both devices: functions can be wired differently, or not be implemented depending on the intended application.

This is the case with the following examples:
Figure 8: - permanent location beacon: emits (3) in
permanently and cyclically (with access control to
frequency) its location message. The reception
tor (4) is not essential.

Figure 9: - location tag on loop: emits (3) sound
location message when a vehicle passes by
a buried loop (5) (coupling possible with
traffic light control)
Figure 10: - triggered location tag: does not emit (3)
its location message only on receipt (4)
mobile identification (normal operation
of the process described above.

Figure 11: - location beacon with external exit: which
that this is the use of this tag, and if it is
equipped with suitable option, reception (4)
of an identification message automatically causes
its transmission to external equipment (6)
(mesh network: to front end of management computer
for example, ..., independent tag: towards an equi
locally connected, for toll ticket output
for example,...)
Figure 12: - location beacon without transmitter: only the receiver
tor (4) of the tag is active, and sends the
identifications received towards an equipment (6)
external (passage identification for example ...)
Figure 13: - permanent identification tag: emits (3) in
permanently and cyclically (with access control to
frequency) its identification message (function
normal process described above). The
receiver (4) is only essential if
wants to connect external equipment (6).

Figure 14: - identification tag manually triggered;
only emits (3) its identification message on
operator control (traffic light control at
distance for example, guarding round management,
...)
Figure 15: - identification tag triggered by the receiver:
only emits (3) its identification message
reception (4) of a location message.

Figure 16: - identification tag with external exit: what
whatever the use of this tag is, and if it
is equipped with the appropriate option, reception (4)
an identification message causes automatic
only its retransmission to an equipment (6)
outdoor (to on-board computer, to
fleet management via the vehicle's radiotelephone,
etc ...). The transmitter (3) is not essential.

It is obvious that all of the above operating modes are not restrictive, and that other combinations are possible.

We will now describe in more detail the two devices in their preferred embodiment.

A) FIXED BEACONS (figure 17)
They are designed to be low cost, energy independent
a priori, maintenance-free and very simple to set up. For that
an interesting embodiment of the device consists of a terminal
buried (1) of cylindrical shape to be easily installed
lée in the roadway with a hole saw. The only part over
health above the road consists of a portion of the globe (10)
transparent to allow recharging of solar energy and ser
front of the antenna support (11) of the beacon.

An embodiment of this tag includes, in addition to the solar cells
res (12) arranged under the transparent surface, a battery
rechargeable (13) allowing significant autonomy, a
mains charger (14) when the beacon is disposed near
an electronic card (15)
able to support transmitter / receiver circuits, logic
control, power regulation and serial or paral interface
link to external equipment, when installed.

It is obvious that any other solution concerning the food
energy consumption of these tags is possible (bio-energy, etc.),
allowing then to use an opaque part of the globe (10)
(type rado ne).

B) MOBILE BEACONS (figure 18)
They include the elements of the fixed tag with regard to:
- the antenna (11) and the portion of the globe (10)
- the electronic card
The whole is arranged in an extra flat waterproof case (2)
can be placed, for example, under a vehicle (fig. 19).

We will finally give some technical details in a preferred embodiment of the device.

The antenna and the transmitter are designed so as to have omni-directional radiation and a range of the order of 5 m. The installation of fixed beacons in the roadway must be planned accordingly.

For vehicles moving at maximum 130 km / h, and if two complete identification-location cycles are required over 5 meters of movement of the mobile, the complete cycle must last approximately 70 ms. By counting a dead time of a quarter of the cycle, there remains around 52 ms for data messages.

The location code is chosen so as to allow direct location from a Lambert type kilometric grid system: we will choose 6 digits for the abscissa (precision of ten meters), 6 digits for the ordinate ( idem), 1 digit for elevation (10 levels possible), 1 digit for function (here location) and transmission control. In B C D coding, a 7-byte coding is therefore obtained for the location data.

The identification code allows, pat exempt, the coding of 999,999,999 mobiles, ie 9 digits and 1 digit for the function (here identification) and the validity check of transmission. In B C D coding, a 5-byte coding is therefore obtained for the identification data.

A preamble is assumed a priori (for the synchronization of reception of the order of 2 ms for each of the messages. There then remains a coding time per byte of 4 ms, ie a transfer of 2000 bits / s.

Depending on the frequency band authorized by the P.T.T., we can therefore use a modulation of 2400 Bauds, or 1200 Bauds in dibit, ...

Claims (7)

R E V E N D I C A T I O N S 1.- Method for locating mobile elements over the air or  infrared characterized in that it allows reversibility  location-identification. 2.- Method according to claim 1, characterized in that ef  automatically performs the following operations:  a) the identification equipment cyclically sends a message  b) receipt of this message by the locating equipment  causes a location message to be sent. 3.- Process in accordance with claims 1 and 2, characterized in that  the previous cycle (identification message, localization message  tion), when fully and properly accomplished, is  inhibited for a preset time to allow the cycle of au  very identification equipment. 4.- Method according to claim 1 and 2a characterized in that it  allows the use of fixed infrastructure in the identification network  of passages. 5.- Telecommunication device over the air (or infrared)  between fixed location beacons and mobile beacons  identification characterized in that the same technology is used  and that they differ only in the wiring of their functions and  the options that compose them. 6.- Device according to claim 5 characterized in that the  mobile beacon consists of an antenna placed on a spherical part  risk, of an electronic card which may include a transmitter, a  receiver, control logic, power regulation,  a serial or parallel interface to external equipment. 7.- Device according to claim 5 characterized in that the  fixed beacon is easily implantable in the roadway, and com  laying, in addition to the elements defined in claim 6, of cel  solar cells, battery and mains charger.