SYSTEM FOR SURVEYING AND SIGNALLING THE PRESENCE OF OBSTACLES ON THE ROADWAY

The present invention basically relates to the transport sector, and in particular to a system that can detect hazards for motorists, such as sudden slowing-down in the traffic conditions as a result of queues due to work being carried out on the road, as well as the presence of ice and/or obstacles on the roadway, such as for example vehicles that are standing still on account of breakdowns or on account of an accident, said system signalling the presence of said obstacles in due time to other vehicles that are approaching.

According to a peculiar characteristic of the invention, the aforesaid detection occurs even in the presence of fog, in the absence of light, or in adverse weather conditions that reduce visibility, such as intense rain, hail etc.

STATE OF THE ART

Currently installed on roads and motorways are guard-rails and posts provided with "passive" reflective cat's eyes or gems, the only function of which is that of delimiting the roadway and signalling the path thereof.

A -first attempt to render the cat's eyes or gems "active" has been made by connecting them to a sensor for detecting fog and causing them to light up to signal the presence of a fog bank on the roadway, as well as to render them more visible for drivers, who in this way are facilitated in recognizing the edges of

the roadway also in conditions of visibility limited by fog.

At present, when there is a sudden slowing-down of the motorway (or road) traffic due to a narrowing of the roadway or carriageway on account of the presence of roadwork sites or else a road accident, for example in the presence of fog, there is an extremely high danger of pile-ups, which regularly occur every year on the roads and motorways in Italy and in other countries and that manage to involve even hundreds of vehicles, causing many fatal and non-fatal casualties.

The known system just referred to is only able to signal the presence of fog but not that of a possible obstacle constituted by vehicles that are standing still or are involved in accidents that are present on the roadway.

In order to prevent the occurrence of pile-ups or collisions in general, it would be desirable to be able to give advanced notice in some way to vehicles that are approaching the site of the accidents or the areas in which a traffic jam is present.

Also known are signalling systems, in which cat's eyes or similar gems set along the roadway are remotely activated/deactivated by a control centre that receives information from the competent authorities (road police, national road boards, etc.) and/or by means of sensors for detecting the weather conditions, the road and traffic conditions, etc. In this case, activation/deactivation of the gems is evidently subject to inevitable delays due to the technical times involved in the communication of the weather or traffic

conditions .

The main purpose of the present invention is to overcome the aforesaid problems by providing a system capable of detecting the presence of obstacles of any kind that may be encountered on the roadway, and to activate visual-signalling devices capable of warning oncoming vehicles directly when they are still at an appropriate distance (for example, 500 metres or more) so that they can slow down to prevent collisions or sharp braking. In other words, the invention enables activation of a direct interaction (in real time) between the road and the motorist, without any human mediation, so that the motorist will behave as if he had actually "seen" the accident and/or the problem and will have time to put into effect all those safety manoeuvres and appropriate behaviours to avoid getting involved.

The above purpose is obtained, according to the invention, by providing a system comprising a plurality of gems, which are not simply reflective but, instead, are also "smart", each of which is equipped with means for detecting obstacles, means for remote signalling of the presence of a hazard, and means for visual and/or acoustic signalling of the state of danger. A better understanding of the invention will be obtained from the ensuing description and with reference to the attached plate of drawings, which illustrate, purely by way of non-limiting example, some preferred embodiments. In the plate of drawings:

- Figure 1 shows a diagram of the principal

elements of the invention;

- Figure 2 is a schematic illustration of a second embodiment ;

- Figures 3A-3E show the different states of operation of the LED display;

- Figure 4 represents schematically, as a whole, a system according to the present invention;

- Figures 5A and 5B are, respectively, a front view and a side view that show schematically a further embodiment with a substantially cylindrical body;

- Figures 6A and 6B show an example of the areas of coverage of the sensors in the case of a motorway/freeway with three lanes for each direction of travel, plus an emergency lane; - Figures 7A and 7B show an example of the areas of coverage of the sensors in the case of a motorway/freeway with two lanes for each direction of travel, plus an emergency lane;

- Figure 8A shows an example of the areas of coverage of the sensors in the case of a single- carriageway road with two lanes, i.e., one for each direction of travel, without central strip;

- Figure 8B shows an example of the areas of coverage of the sensors in the case of a single- carriageway road with four lanes, i.e., two for each direction of travel, without central strip;

- Figure 9 shows a first embodiment of the gem according to the invention;

- Figure 10 shows a variant of Figure 9; - .Figure 11 shows a second embodiment of the gem according to the invention;

- Figure 12 shows a third embodiment of the gem according to the invention; and

- Figure 13 is a block diagram of a possible configuration of the gem according to the invention. The system according to the present invention bases -its operation upon a plurality of innovative reflective gems, located at the edges of the roadway, each of which comprises, in combination: sensors for identifying the presence, position, and speed of vehicles (or of obstacles) on the roadway; radiofrequency devices for remote signalling of the state of danger; visual and/or acoustic signalling devices present at the site of the road hazard that has been detected; as well as batteries 10 for electrical supply of the aforesaid sensors and devices.

The inventive idea underlying the invention lies in the fact that each of the "smart" gems described constantly monitors a stretch of road that it is surveying and, in the case where at least one of said gems detects a danger situation, said gem signals the presence of the hazard both visually and in radiofrequency to the gems that precede it with respect to the direction of travel. After this, a certain number of gems that precede the gem or gems that has/have detected the danger situation are activated, in turn signalling both visually and via radio the presence of a hazard: in this way, drivers of vehicles approaching the point in which there is the situation of danger, are immediately alerted and can thus see in enough time to slowing down or, if necessary, stopping, without the risk of causing collisions or accidents

(Figure 1) .

The vehicle that has consequently slowed down or stopped as a result of the visual signal in turn becomes a danger for the vehicles that follow it, but the gems in the proximity of which it is located detect it and, if its presence/speed constitutes a danger

(overstepping of the pre-set alarm thresholds) , said gems are in turn alerted and re-propagate the alarm to other gems. Said propagation of alarm is repeated until the vehicles (gradually) resume a speed of travel that no longer constitutes a danger for the vehicles following, and consequently the gems deactivate their alarm, communicating their new state, in radiofrequency, to the gems that had issued the alarm previously. The traffic consequently resumes its normal flow.

In a first embodiment of the invention, said sensors for detecting the presence, position and speed of vehicles that are standing still on the roadway are constituted by at least one magnetometer 1, one or more infrared sensors 2 that are sensitive to the variations and/or differences of temperature, at least one microphone 3, and at least one radar sensor 14.

The magnetometer is designed to detect the presence of vehicles located at a distance of up to 15 metres; it also supplies data on the envelope (shape of the vehicle), speed and direction of traffic flow.

The infrared sensors used come from various technologies, supply information regarding the passage of vehicles in the range of detection of the gem, and detect the possible presence of objects occupying the

roadway even in adverse weather conditions, such as for example fog.

The radar sensor supplies information regarding the speed and possible occupation of the roadway by vehicles that are standing still or slowing down, enabling also signalling of queues.

In order to reduce the likelihood of error, each gem is. preferably equipped with a main low-consumption

CPU, designed to process the output data by purposely provided analog-to-digital converters, which carry out a first adaptation of the levels of the signals and filtering thereof (Figure 13).

The main CPU sees to correlating the data supplied by the sensors and to combining them both from the logical standpoint and from the arithmetic standpoint to calculate the alarm conditions and select the level of alert to be activated.

The means of visual signalling in situ of each gem are constituted by a reflective display facing oncoming vehicles, which comprises a series of high-luminosity

LEDs 8 ' (preferably red) inserted in the reflective gem, which are driven by the main CPU; the process of lighting-up of the series of LEDs of the gem is preferably incremental and is activated in the event of need, i.e., when the CPU, on the basis of the data acquired by the sensors, and updated in real time, supplies an alarm signal.

The means for remote radiofrequency signalling comprise a transceiver module, constituted by a frequency-modulation transceiver and by a self- contained transmission antenna 9. According to the

invention, a "burst" spread-spectrum or frequency- hopping modulation can be used, and the transmission bandwidth used for wireless communication is the ISM (Instrument-Scientific-Medical) bandwidth. The effective range of transmission of the alarm signal is preferably approximately 300 metres in free field.

The transceiver module operates under the control of a CPU, which sees to managing both the wireless communications and the interface with the sensors and the LEDs of the display. This module implements a state machine to solve and hence handle all the steps of reception, transmission, acquisition, and control and is aimed at managing the operating states directly via a programmable logic that contains the absolute reference time to activate sequentially all the states of the system.

Each gem of the system according to the present invention is advantageously able to perform self- configuration of its own state of operation, in the network to which it belongs, thanks to the use of a powerful routing algorithm that is able to deliver the data packets successfully. In the case of adjacent gems not functioning, the single node has a transmission range that is sufficient to reach as far as two successive nodes both forwards and backwards with respect to the direction of travel.

The gem uses integrated circuits with extremely low consumption; only the transceiver, on account of the transmission power (+10 dBm) absorbs more energy. This is in any case managed in time, since the transmission is of the synchronous packet type in time-

division multiple access (TDMA) . The radar sensor is used in a "pulsed" way, with the choice of an appropriate duty cycle that will keep the levels of consumption within acceptable values for the application. The LEDs are of the low-consumption type to limit further the expenditure of energy.

To achieve the maximum autonomy possible for the battery, which is preferably of the lead-acid-gel type, each gem comprises a subsystem dedicated to management of the energy, which optimizes the use of electronic circuits in all the possible conditions, also of ambient temperature. Said subsystem is substantially responsible for "waking up" the transmission system and the display in the event of detection of an alarm condition by its own sensors or else after an alarm message has been received from one of the adjacent gems .

At this point, it should be recalled that the colour of the reflective gems located at the edges of the roadway is different according to the type of road. In fact, the gems of motorways and freeways are both yellow (both on the right and on the left of the carriageway) , whilst the gems for single-carriageway roads are red for the right-hand side and white for the left-hand side.

It is consequently evident that, according to the type of road on which the gems of the present invention are to be installed, the colour of the reflective display must be the right one. A second embodiment of the invention (Figure 2) that is particularly useful for unifying the production

making it possible to have at the most just two products to meet the requirements of all types of roads, envisages providing a gem constituted by a triangular prism with the three faces coloured with the colours that are necessary in the various cases of use:

1. yellow/orange face Y: for use on motorways and freeways;

2. ruby-red face R: for use on the right-hand side with respect to the direction of travel on single- carriageway roads; and

3. diamond-white face W: for use on the left-hand side with respect to the direction of travel on single-carriageway roads.

In order to fix the gem to the fixed support (guard-rails or supporting posts) means of a known type may be conveniently used.

A further embodiment of the invention, represented schematically in Figure 5, has a substantially cylindrical external shape: in this case, the outer casing is constituted by a cylindrical body divided into two superimposed coaxial cylindrical sections. The bottom section contains all the electronics, as well as the sensor circuitry, supply, and alarm panel. The top section, with the oblique top face, is free to rotate about the central axis of the same cylindrical casing, and is driven by an electric motor. Internally it contains, as supply source for the system, a photovoltaic cell, fixedly installed on which is a Fresnel lens, which concentrates the sun's rays. To enable a good efficiency of the system formed by the photovoltaic cell plus the concentrating lens, which

hereinafter will be referred to as a whole as "supply cell PV", the top cylindrical section is moved by two electric motors : one for rotation about the axis of the cylindrical body, which enables its rotation in the horizontal plane; and another for rotation about an axis perpendicular to the axis of the cylinder and underlying the supply cell PV, which enables this to rock (i.e., rotate and translate) about its centre.

In said cylindrical embodiment then, which is to be considered the preferred one, the energy-management subsystem sees to managing the battery charge through the concentrating photovoltaic cell. In order to optimize the efficiency of said cell, an electric micro-motor system is provided, controlled by the CPU. By means of an algorithm for pointing the sun, based upon the acquisition of data from obscuration sensors, the CPU manages the movements of the supply photovoltaic cell, forcing it to follow the sun so as always to have the maximum irradiation on its surface. According to the invention, it is advantageously possible to envisage visual signalling of the presence of danger in an incremental way, i.e., increasing the number of the LEDs lit up and/or flashing as the obstacle is approached. In other words, the gems furthest away from the site of the danger (for example, at a distance of 1 km before the obstacle or in any case at an adequate distance from the obstacle, chosen on the basis of the type of road, of the particular layout in which the gems are installed, etc.) will have only a few LEDs lit up, whereas in the nearest ones an increasingly larger number of LEDs will be lit up until

all the LEDs are lit up and/or are flashing (for example, for distances of less than or equal to 250 m) . When a gem goes into an alarm condition, the preceding gems are activated, up to a pre-defined distance from the obstacle and/or from the queue. The alarm signal due to the presence of obstacles on the roadway is preferably effected by increasing the number of rows of LEDs lit up every 250 metres.

When they are lit up, said LEDs are preferably red, either permanently on or flashing.

From what has been said, the motorist that approaches the danger area encounters reflective gems, which,, instead of being in a state of normal operation (Figure 3A) , show a state of partial activation of the LEDs (Figure 3B) . As the motorist approaches the danger area, he notes that the number of the LEDs lit up increases, as illustrated in the subsequent Figures 3C- 3E, until all the LEDs are lit up of if the distance from the obstacle is less than or equal to 250 metres. With reference to Figure 4, the system implemented is constituted by a series of intercommunicating smart reflective gems, each of which is equipped with at least one magnetometer 1, one or more infrared sensors 2, at least one microphone 3, and one radar 14 in order to detect, in the range of coverage envisaged, the presence of vehicles that are stationary or, at that moment, are travelling at a particularly slow speed with respect to the speed of the vehicles that are approaching on the roadway according to a diagram that covers the two/three lanes 4 and ignores the emergency lane 5.

From a combination of the different input values of the' sensors, the central processing unit or CPU 6 is able to calculate the speed and position of the vehicles and, if need be, send the gem into an alarm condition.

As has already been mentioned, the structure of the gem can be a right prism with triangular base 7: of the three reflective side faces one is ruby red, the second diamond white, and the third yellow/orange to meet the various needs of use, and said faces are provided with a plurality of red LEDs 8.

By means of the transmission antenna 9, the gem that has gone into an alarm condition propagates a state of alarm to the preceding gems, which are activated, by lighting up the LEDs with which they are equipped, preferably according to an incremental scheme.

According to this scheme, the alarm signal goes into action, lighting up all the LEDs of the gem that has detected the hazard and of those that precede it, reducing every 250 metres the number of LEDs lit up, until the gems that are located at the maximum predefined distance from the gem that has detected the presence of an obstacle on the roadway are reached. For installations on motorways and freeways, the invention can advantageously be integrated with the SOS columns 12. For this purpose, it is envisaged that each SOS column is equipped with a control unit that is able to manage the gems installed in the stretch that it surveys and in particular the one set between two successive columns. Monitoring of the state of the gems

enables the SOS column to receive the signals of:

- state of alarm;

- battery low;

- breakdown. The SOS columns, connected to the control centres of the relevant area, are able to forward the alarm signals coming from the gems so as to enable timely intervention of rescue and breakdown vehicles, ambulances, and the road police. According to the invention, each SOS column can be further equipped with a high-visibility rotating beacon 13, which will be activated in the case where the alarm signal is received from one of the gems of the area that it is surveying. A second peculiar characteristic of the invention consists in the fact that signalling of the danger for oncoming vehicles is "self-regulating". In fact, if for example a vehicle is standing still in a non-emergency lane, the gem that detects is activated, giving rise to the signal now described starting from the same vehicle that is standing still - for a pre-defined distance - in a direction opposite to the direction of travel, but evidently if other vehicles add on to the first, so creating a queue, each of the gems of that stretch of road will detect one or more vehicles that are stationary and consequently will signal said situation for the pre-defined distance. In other words, the activated gems will always be at least the ones corresponding to the pre-defined distance prior to the last vehicle that is standing still, and, if the queue grows, the active gems increase accordingly in a

direction opposite to the direction of travel.

Advantageously, in order to prevent the waste of the available energy that would occur by leaving the gems unnecessarily active when the queue has already formed ^" , according to the invention it is envisaged to interrupt the visual alarm signal automatically when said signal proves useless .

From what has been said, it appears clearly that, when the queue starts to move, re-establishing a normal vehicle flow, the first gem that was activated returns to the stand-by state, and the same applies to the gems that precede it, until the entire queue has been dissipated.

According to a further peculiar characteristic of the invention, each control centre 15 is able to drive the SOS columns to send the gems managed thereby into the alarm condition in order to signal any possible problems on the roadway that are independent of the vehicles travelling thereon (presence of ice, roadworks in progress, fires, smoke, wind, rain, snow, fog, adverse weather conditions, etc.) according to a modality of communication that may vary on the basis the seriousness of the event to be signalled.

Apart from this, according to the invention each gem is preferably equipped with self-analysis means that detect possible breakdowns, operating faults, and the state of the batteries, and then communicate said information to the control centre so that the manager can decide whether and how to intervene. Spectrograms of the detection sensors (magnetometer, infrared sensors, microphone, radar)

The spectrogram of the magnetometer enables coverage of a portion of surface with an angle of 180°; this enables reduction in the number of gems necessary for coverage of the roadway. The spectrograms of the infrared sensors are combined in such a way as to guarantee a total coverage of the carriageways, and simultaneously such as to guarantee the detection of false alarms coming from vehicles standing still in the emergency lane. The spectrogram of the radar sensor covers a portion of surface of at least 50 metres, with an angle of at least 14°.

Optimization of positioning of the accumulators for supplementary supply Motorways and freeways afford a situation that is rather advantageous for application of the invention in so far as the central gems of the two carriageways are set in the same point. Consequently, by positioning the accumulators in the areas of installation of the pair of gems it is possible to supply both of them using models of longer duration given that the higher cost will be compensated for by the smaller number of installations required (not illustrated) .

ANALYSIS OF THE AREAS OF MONITORING OF THE SENSORS First case of application: dual-carriageway motorway/freeway with 3 lanes + emergency lane (Figures 6A-6B) . Fast overtaking lane and overtaking lane: 3.75 m; slow lane: 3.5 m; and emergency lane: 3 m.

On this hypothesis, a number of IR alarm sensors (preferably five) is envisaged on each of the central gems of the roadway (set, that is, on the left-hand

side of the latter) , plus other (preferably two) IR sensors for masking false alarms on each of the gems of the emergency lane.

Alarm gem: Central sensor Sl (dotted line - central position): angle of 76°, and range of 14 m.

Intermediate sensors S2 (dashed and dotted lines - one for each direction) : angle of 22°, and range of 21 m. External sensors S3 (lines with circles - one for each direction) : angle of 30°, and range of 28 m.

Theoretically, one gem would be necessary every 56 m; in practice, one gem is sufficient every 50 m.

Gem for masking false alarms: Masking sensors S4 (dashed lines - one for each direction): angle of 3°, and range of 55 m.

Theoretically, one gem would be necessary every 55 m; in practice, one gem is sufficient every 50 m.

Evaluation of overlapping areas: hypothesising overlapping of 4°, the angles become: external sensors S3 = 32°; intermediate sensors S2 = 26°; central sensor Sl = 80° (2 x 40°) .

Mode of detection: the (central, intermediate and external) sensors of the alarm gem positioned on the left-hand side of the carriageway, are able to detect a stationary obstacle on the roadway and to go into an alarm condition. In the case where the obstacle is on the emergency lane (e.g., breakdown of vehicle) there is a false alarm that must be masked. Masking of the false alarm is effected with the aid of the (masking) sensors of the masking gem, positioned on the right-

hand side of the carriageway, which are able to detect the presence of the obstacle on just the emergency lane .

It should be noted that in the curvilinear stretches it will be necessary to increase the number of gems (and hence reduce the relative distance) positioned on the concave side of the carriageway - that is, the inside of the curve - in so far as the sectors covered by the different sensors are no longer adjacent to one another.

Second case of application: dual-carriageway motorway/freeway with 2 lanes + emergency lane (Figures 7A and 7B). Overtaking lane: 3.75 m; slow lane: 3.5 m; and emergency lane: 3 m. On said hypothesis, five IR alarm sensors are provided on the left-hand side gem, plus two IR sensors for masking false alarms on the gem of the emergency lane.

Alarm gem: Central sensor Sl (dotted line - central position): angle of 104°, and range of 10 m.

Intermediate sensors S2 (dashed and dotted lines - one for each direction): angle of 14°, and range of 18 m. External sensor S3 (lines with circles - one for each direction) : angle of 24°, and range of 26 m.

Theoretically, one gem would be necessary every 52 m; in practice, one gem is sufficient every 50 m.

Gem for masking false alarms: Sensors S4 (dashed lines - one for each direction) : angle of 3°, and range of 55 m.

Theoretically, one gem would be necessary every 55 m; in practice, one gem is sufficient every 50 m.

Evaluation of overlapping areas: hypothesising overlapping of 4° the angles become: external sensors S3 = 26°, intermediate sensors S2 = 18°, central sensor Sl = 108° (2 x 54°) .

Third case of application: single-carriageway road with 2 lanes (1 for each direction of travel) without central strip (Figure 8A) . Lane: 3.5 m. On this hypothesis, two IR sensors are provided, or else one IR sensor per gem, installing the gems so that they alternate on the two sides of the roadway out-of-phase by D/2, with D = 15 m (where D is the distance between two gems of one and the same side of the roadway) .

Alarm gem:

A pair of sensors S5 that are identical to one another and set alongside one another with an angle of 95°, and range of 7 m. or else

A single sensor Sβ with an angle of 180°, and range of 7 m.

Theoretically, one gem would be necessary every 14m; in practice, one gem is sufficient every 15 m (thanks to the alternated positioning on the two sides of the roadway) .

Mode of detection: the IR sensors, in the event of arrest of the vehicles, activate the light signal on both of the lanes of the roadway. Fourth case of application: single-carriageway road with 4 lanes (2 for each direction of travel)

without central strip (Figure 8B) . Overtaking lane: 3.5 m; slow lane: 3.5 m.

On this hypothesis, two passive infrared (PIR) sensors are provided for each alarm gem, which are able to detect the direction of travel, installing the gems so that they alternate on the two sides of the roadway out-of-phase by D/2, with D = 30 i. Alarm gem:

A pair of identical sensors S7 with an angle of 95°, and range of 14 m.

Theoretically, one gem would be necessary every 28 m; -in practice, one gem is sufficient every 30 m (this is possible thanks to the alternated positioning on the two sides of the roadway) . Mode of detection: the PIR sensors (two for each gem) are able to detect the direction of the vehicles travelling. In the event of the vehicles stopping, the gem, on the basis of the direction of travel detected, will activate the light signal on the side of the roadway concerned.

According to the invention, the IR sensors are substantially of two types: pyrometers and microbolometers . In gems just for emergency lanes only IR sensors of a pyrometric type are used, whilst in gems for non-emergency lanes IR sensors of both types are installed.

A first example of application of the invention envisages a cube equipped with two smart gems (Figure 9) • On motorways and freeways where a single central guardrail or a New Jersey median barrier made of

reinforced concrete is present, it is possible to envisage installation of a cube, mounted, i.e., set in, in two opposite edges of which are two smart gems having the shape of a right triangular prism. Set on the inside of the cube are the rechargeable accumulators, whilst the surfaces of the cube are coated with photovoltaic cells.

A variant of the invention envisages a cube provided with two smart gems in relief (Figure 10). On motorways and freeways where wide bends are present, location of smart gems in relief on the supporting cube may be envisaged.

A second example of application of the invention envisages a sphere equipped with two spherical-cap smart gems (Figure 11) .

In order to distribute the sensors better on the outer surface of the smart gem, it is possible to envisage a spherical structure of the case of the system. The smart gems to be installed thus have the shape of a spherical cap and are positioned on two opposite faces of the central cube for storage of the batteries. Mounted on the top face is a surface with solar cells capable of recharging the internal accumulators. The bottom face is located on the support provided for fixing to the New Jersey median barrier.

The remaining two side faces can be used for positioning a LED display for light signalling of the alarms generated by the gem.

A third example of application of the invention envisages a sphere equipped with two smart gems having the shape of a spherical shell (Figure 12) .

In order to distribute the sensors better on the outer surface of the smart gem, it is possible to envisage a spherical structure of the case of the system. In addition, it is possible to conceive two smart gems shaped like a spherical segment that are able to rotate on the outside of the case. Between the two shells of the gems it is possible to insert the shell provided for the LED display to be used for light signalling of the alarms generated by the gems. It should be noted that it is preferable to use the gems having the shape of a spherical segment for installation on the central strips of motorways and freeways, whilst for the corresponding masking of the false alarms on motorways and freeways and for installations on single-carriageway roads it is preferable to use gems having the shape of a right triangular prism.