WARNING SYSTEM FOR DETECTING APPROACHING OBJECTS

Abstract: Warning system for warning of the approach of an object (18) along an identified path (13) to a position (15) on said path comprises means (16) for detecting the approaching object at a predetermined distance from said position (15), and means for providing a warning indication at or transmittable to said position in response to said detection. The system is suitable for use by personnel working on disabled vehicles (14) on a motorway hard shoulder, to provide warning of any other vehicle (18) that inadvertently strays from the main carriageway (12) onto the hard shoulder (13).

Description: WARNING SYSTEM FOR DETECTING APPROACHING OBJECTS This invention relates to a warning system operable to provide warning of an approaching object and in particular, although not exclusively, for warning personnel of an approaching object that is a hazard, or constitutes a potential hazard. The invention has been devised with particular but not exclusive intent that it should be suitable for use by personnel working on disabled vehicles at the side of roads. Many accidents have occurred where a vehicle has broken down and, despite the fact that it has been parked off the main carriageway of a road, it has nevertheless been hit by another vehicle. Typically such accidents have occurred on motorways, or roads of or approaching motorway standard, where the broken down vehicle has been able to pull off the main carriageway on to the hard shoulder or roadside verge, but has been hit by another vehicle which has strayed from the carriageway on to the hard -shoulder or verge because the driver of the other vehicle has lost concentration or fallen asleep. For this reason it is recommended that when a vehicle breaks down on the motorway the driver and any other occupants should leave that vehicle and wait as far away from the main carriageway as possible until assistance arrives. However, a person or persons rendering such assistance, e.g. by carrying out repairs on the vehicle, almost invariably has to work on the vehicle in the position where it has been left, and there have been cases where emergency services personnel or mechanics have suffered accidents while carrying out such work. Although it is the normal practice of a person attending a stationary vehicle on the motorway to park his or her vehicle behind the stationary vehicle on the hard shoulder to afford some protection, particularly if his vehicle has readily visible warning lights or the like, this affords no real protection if a heavy commercial vehicle, or even a light vehicle travelling at high speed, deviates from the main carriageway on to the hard shoulder. Similar hazards are experienced by those who carry out motorway or road maintenance and construction work, and those who work on or near aircraft runways. An example of yet another, substantially analogous, hazard is that which arises in the maintenance of railway track and track-side equipment. As a safeguard against errors in temporary signalling arrangements or malfunction it is conventional practice to require patrol personnel to be stationed along the track at a suitable distance from a track section being worked on, to maintain a watch and provide an evacuation warning when a train approaches. Clearly that procedure suffers from the disadvantage of being exposed to the risk of human error, and also is costly. One object of the present invention is to provide a warning system suitable for warning personnel of an approaching object which is or constitutes a potential hazard, such as a warning system for assisting the safety of persons working on broken down vehicles or at track locations in situations such as those described above. A further object of the present invention is to provide a warning system of said type and which is hand or vehicle portable. According to one aspect of the present invention, I provide a warning system for warning of the approach of an object along an identified path to a position on said path, comprising means for detecting said approaching object on said path at a predetermined distance from said position, and means for providing a warning indication at or transmittable to said position in response to said detection. The system may comprise means which detects at a plurality of predetermined distances (or over a range of distances) from said position on said path. Thus the system will then be able to detect a object which enters said identified path at a distance which is less than a maximum pre-determined distance at which the system is designed to be capable of detecting an object. When the system is in use to provide a safety warning to personnel in the event of an approaching vehicle, the distance from said position at which the approaching vehicle can be detected is determined so as to give a warning at said position with sufficient time for a person working at the position to move away therefrom, for e.g. an average or typical maximum speed of travel of vehicles in the vicinity of said position. Thus the system may comprise a speed vs. distance threshold reference map which is adjustable having regard to e.g. the potential maximum speed of an approaching vehicle. A system in accordance with the invention may be used in the situation above described of the hard shoulder of a motorway or the verge of a high speed road, in which case the path on which the presence of an approaching vehicle is detected at a predetermined distance from the position is the hard shoulder or verge, as the case may be. In the case of vehicles travelling at 90 km/h, to detect the presence of an approaching vehicle at a distance of 125m (150 yards) from the position gives a warning approximately 5 seconds before a vehicle reaches a position. This is adequate time for personnel at said position to vacate the position before the approaching vehicle reaches the position. In the case of use of the system on a motorway, where average speeds are higher, one might want to detect the approach of a vehicle at substantially more than (125m) 150 yards distance from the position, in order to give an adequate warning time. The invention further provides that the system comprises location discrimination means whereby when, for example, it is to be used on a road or motorway, it should be able to discriminate between vehicles travelling on the main carriageway, which represent no substantial danger to a person on the hard shoulder or verge, and vehicles approaching on the hard shoulder or verge which do present such a danger. Thus the invention provides, more generally, a system having location discrimination means operable to discriminate between an approaching object that presents a hazard and one which does not present such a hazard. The system may comprise means for discriminating between an approaching vehicle on said identified path and one on a path alongside or proximate said identified path. A laser range finding technique may be utilised, the very narrow beam of coherent light which can be produced by a laser device being extremely suitable for this purpose. The means for detecting the approaching vehicle may comprise a radar beam or the like which emits radiation and detects an echo in the case of an approaching vehicle being in the beam. Such a beam requires to be of a high quality, e.g. sufficiently narrow to be directed along a path whose width is of the order of that of a motor vehicle, such that it does not respond to a vehicle on a closely adjacent path. Preferably the beam has a width of less than 2 meters, more preferably less than 1 metre at a distance of 150 metres from the detecting means. A beam having an operable, working width (i.e. width of usable signal strength) of less than 0.5 metres may be employed, and may be provided by a laser beam. The beam may be of non-circular shape, and may be orientated to have a height greater than width, preferably a height greater than 3 times the width when used for monitoring along a motorway hard shoulder. Another means for detecting an approaching object, and particularly suitable if the object comprises parts at above ambient temperature as in the case of a motor vehicle, comprises a thermal sensing device. Whist the use of a high quality beam of a well controlled direction and width, such as a laser beam, generally is preferred, a beam having a less well controlled radiation direction or pattern may be employed, and may be used in conjunction with a remotely positioned gate or other device so that only radiation passing through the gate and reflected back by an approaching object is detected. At least one of the system detecting components, e.g. an emitter or a receiver, may be adapted for positioning remote from a means for providing the warning signal. Thus, for safeguarding a motorway breakdown vehicle one detection means may be located on or in a road safety cone, and several spaced cones and auxiliary detection means may be linked to act together if the section of road approaching the breakdown vehicle is curved, at least some of the successive detection means being arranged each to detect over only a respective limited part of that total distance constituting the aforementioned predetermined distance along said identified path. The warning signal given at the position may be audible and/or visible. It should be sufficiently loud and/or bright and/or appropriately positioned to be detectable in the presence of high speed traffic passing close by. Other types of warning signal may be employed, such as a vibrator which may be of the kind employed in personal pager devices. A warning signal of that type is particularly suitable for personnel operating in noisy and bright (e.g. full sunlight) conditions in which audible and visual warning signals may not be immediately recognised. The components for comprising a system in accordance with the invention may be provided in close association with one another, and thus may be provided on a single vehicle or on some other item of equipment. Thus a breakdown vehicle, tow truck, vehicle used by emergency vehicles, or the like, may be provided with a system in accordance with the invention. Alternatively at least a part of the system could be provided on a road warning sign, a safety barrier or the like, or even on the ubiquitous "road cone", or built into an adapted road cone. The detecting means and warning means may be substantially integral with one another or may be provided as separate units. Communication therebetween may be achieved wirelessly, (e.g. by radio frequency wave transmission) or by a wired interconnection such as by means of a cable or optical fibres or otherwise. As well as detecting the presence of a vehicle approaching on the identified path, the system may comprise speed discrimination means for the detection of the speed of such approach. Then, it is possible for the system to discriminate between a vehicle (or other object) approaching at high speed which clearly presents a hazard, and an object approaching at a low speed which presents no or a much reduced hazard. There may be a threshold speed, which may be able to be set as required, between the system operating to provide a warning and no such warning being provided. In a system which detects the presence of an object at a plurality of predetermined distances (or over a range of distances) from said position on said path, it is further taught by the present invention that the threshold speed above which a warning signal is generated shall be a function of distance. Thus a slow moving vehicle at a position some distance away on the hard shoulder would not initially trigger the system to generate a warning signal, but would do so if the vehicle continued at that speed to a closer to said position on said path. In addition to detection of speed of an approaching object the system may take into account deceleration of an approaching object. Thus it may be provided that a fast moving object, such as a police car approaching along the hard shoulder but decelerating rapidly, would not result in a warning signal being triggered. The system may comprise comparator means adapted to compare a first signal derived from monitoring for the approach of an object along said identified path to a position on said path, and a second signal derived from monitoring for the approach of an object in a comparator path which at least in part lies alongside said identified path. For monitoring for the approach of a vehicle along an identified path reference may be made initially to a signal derived from a comparator path which, when viewed in plan, is in the same direction as the identified path, but which is inclined upwards (e.g. at an angle between 2 and 8 degrees) to the horizontal or to the plane of the surface over which an approaching vehicle would travel when in said identified path. A comparator path detection beam therefore is exposed to spurious signals similar to those to those experienced by a detection beam acting along said identified path, due for example to driving rain or vehicle spray, but because of its inclination will not detect an approaching vehicle at least until that vehicle is close to the detector. By arranging that the warning device responds to a difference between signals received along said identified path and along the comparator path it is possible to ensure that false operation of a warning signal by rain or spray is avoided. The system may comprise fail-safe check means to provide that if a vehicle, e.g. a close-by vehicle, is detected in both said identified path and a comparator path, a warning signal will be generated. As an alternative to the use of a comparator path and detection beam, electronic discrimination means may be employed to avoid operation of a warning signal in response to environmental conditions such as driving rain or spray. A reflected signal from an object may be analysed to determine whether one of the signal properties such as intensity or continuity is indicative of a potentially hazardous object or due merely to an inherently non-hazardous cause. Thus, in the case of continuous rain, electronic discrimination means may act to suppress or over-ride any signal component which is continuously present in a reflected signal. The invention provides also a method of protecting road-side personnel working in the vicinity of an emergency vehicle comprising, providing said vehicle with detector means comprising an emitter operable to emit a beam of radiation reflectable by an on-coming vehicle, employing said detector means to detect reflection from an on-coming vehicle travelling along a path leading to said detector means and to discriminate against a reflected signal from a vehicle travelling outside said path, and, in response to detection of another vehicle travelling along said path, to provide said personnel with a warning signal. Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:- Figure 1 illustrates diagramatically in plan view a system in accordance with an embodiment of the present invention; Figure 2 illustrates diagrammatically in plan another embodiment of the invention, and Figure 3 is a side view of part of Figure 2 in the direction of arrow A of Figure 2. In Figure 1 there is illustrated part of a motorway or main road of motorway standard, comprising three traffic lanes 10, 11 , 12 of the main carriageway for one direction of travel, and a hard shoulder 13. A vehicle stationary, e.g. broken down, on the hard shoulder is indicated at 14, and a vehicle attending such stationary vehicle is indicated at 15. The vehicle 15, which may for example be an emergency services vehicle or a vehicle belonging to a breakdown mechanic, is, as is usual practice in such situations, parked behind the stationary vehicle between it and approaching traffic in the near side lane 12. In accordance with this embodiment of the invention, the vehicle 15 is provided with a means for detecting a vehicle approaching along the hard shoulder 13 at a predetermined distance from the vehicle 15. Such detecting means may comprise an emitter 16 for a narrow beam of , e.g. electro-magnetic radiation as indicated at 17, and for detecting an echo thereof from a vehicle 18 approaching on the hard shoulder in the path of such a beam. In response to such detection, and optionally taking into account parameters such as the speed or deceleration of an approaching vehicle to establish whether it constitutes a potential hazard, a warning signal is generated at the location of the vehicles 14, 15, enabling personnel there to move clear. One particularly suitable technique for detecting the approach of a vehicle along a defined path is that commonly referred to as a laser range finding. This utilises a laser light source which directs a short pulse of light in a narrow beam which can be directed along the hard shoulder of a road. A detector device which faces along the same axis detects any reflection returned from a reflective object such as a vehicle. A timing circuit measures the time elapsing between the emission of the pulse and the reflection thereof, which enables a calculation to be made of the distance between the emitter and reflector. The same timing operation for successive pulses enables information to be calculated as to the speed and direction of a moving object reflecting the light. Suitable signal-processing circuitry will be provided to determine whether a vehicle thus detected is within a certain range and is moving towards the detector within a certain speed range. If the approaching vehicle falls within these criteria, then an alarm sequence is initiated. If such criteria are not met, e.g. if an approaching vehicle is too far away or is travelling slowly, an alarm would not initially be given although it will be appreciated that a detected approaching vehicle may come within the criteria for causing a warning signal to be given sometime after it has first been detected under conditions which would not cause the warning signal to be given. It is envisaged that generally the detection system should operate continuously or substantially continuously so that all situations presenting a potential hazard are detected in sufficient time to enable personnel to move clear. It will be appreciated that variations are possible whilst remaining within the broad scope of the invention as set forth herein. For example, instead of the vehicle 15 being provided with the detecting means 16, such means may be provided on a warning sign, "road cone" or the like which may be deployed to provide a visible indication to passing vehicles of the presence of the stationary vehicles on the hard shoulder 13. For example, cones may be deployed as indicated at 19 and one of them may be provided with the detecting means. Warning signs or the like may be deployed some distance away from the vehicles 14, 15, as indicated at 20, and the detecting means may be provided in association therewith, in wireless or wired communication with a warning signal provider in the vicinity of the vehicles 14, 15. In the embodiments illustrated in Figures 2 and 3, a breakdown vehicle 15' is shown at two positions 25,35 on a hard shoulder 13' adjacent a near side lane 12'. One position 25 is at the end of a road section 26 that bends to the left, and the other position 35 is at the end of a road section 36 that bends to the right. In operation at each position 25,35 the detector 16' of breakdown vehicle 15' is arranged to operate in conjunction with a remote detector 27 mounted on a road safety cone 28. The vehicle mounted detector16' detects entry of any vehicle straying onto the hard shoulder at a position between the breakdown vehicle 15' and the cone 28, and the warning system incorporates range finder means to establish the distance between the detector 16' and the cone 28 so that the system can disregard echo signals received by detector 16' from a vehicle further away than the cone 28. Presence of straying vehicles beyond the cone 28 is detected by the cone-mounted detector 27 which in this embodiment points along that remaining required length of the hard shoulder necessary to trigger a timely warning signal. For the left hand bend position 25 the beam from the vehicle mounted detector 16' will intersect the near side lane 12', but only at a position beyond the cone 28 and therefore any echo signal from vehicles in that lane will be disregarded in consequence of operation of the aforementioned range finder means. Figure 3 shows an optional feature in which the vehicle mounted detector 16' emits a first beam along an identified path 30. and a comparator beam 31 is emitted in a similar direction as viewed in plan in Figure 2, but inclined upwards at an angle of about 5 degrees to the level of the road surface 32. In general use, the beam 31 will serve to detect spurious signals caused by driving rain or vehicle spray, and a related signal can then be subtracted from a similar signal related to detection by the lower beam 30 so that the lower beam is operable to trigger a warning signal only in response to an approaching vehicle or other object that constitutes a potential hazard. The present invention teaches also that the warning system may comprise homing means whereby a detector is able to perform a homing operation in which it moves to lie in the required direction, e.g. along the aforedescribed said identified path. In the case of a breakdown recovery vehicle, which for safety reasons often is parked at an oblique angle to the direction of traffic flow, it may therefore be provided that a vehicle mounted detector will automatically move to align itself with a marker type cone that the driver of the breakdown vehicle has deployed on the hard shoulder, the marker type cone being a cone which incorporates means to co-operate with the vehicle mounted detector to enable the latter to identify the cone position. The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof, and a reference to a vehicle may be interpreted as appropriate as a reference to an object and vice-versa.

Claims: Claims. 1. Warning system for warning of the approach of an object along an identified path to a position on said path, said system comprising means for detecting said approaching object on said path at a predetermined distance from said position, and means for providing a warning indication at or transmittable to said position in response to said detection. 2. Warning system according to claim 1 , wherein the system is operable to detect on said path an approaching object at a plurality of distances from said position. 3. Warning system according to claiml or claim2, and comprising discrimination means to discriminate between an approaching object which presents a potential safety hazard and one which does not present such a hazard. 4. Warning system according to claim 3, wherein the discrimination means inhibits operation of the warning means if an approaching object is more than a pre-selected distance from said position and/or is approaching said position at less than a predetermined speed. 5. Warning system according to claim 4, wherein said pre-selected distance is selectively variable by an operator having regard to operating conditions. 6. Warning system according to claim 4 or claim 5, wherein the system comprises a data store for storing predetermined data of potentially hazardous speed of an approaching object as a function of distance from said position. 7. Warning system according to claim 6, wherein speed and distance of an approaching object from said position are monitored substantially continuously and a warning signal is generated only if the instantaneous speed of the object is greater than a predetermined speed as set in said data store for the distance of the object at that instant. 8. Warning system according to claim 6 or claim 7, wherein the data store stores an adjustable speed vs distance threshold map, or a plurality of said maps, whereby a speed vs distance map is adjustable or selectable as a function of the expected maximum potential speed of an approaching object. 9. Warning system according to any one of the preceding claims, wherein the system is operable to inhibit operation of the warning means as a function of the rate of deceleration of an approaching object. 10. Warning system according to any one of the preceding claims and comprising location discrimination means whereby an approaching hazardous object in said identified path causes operation of the warning means, but will not cause operation of the warning means when moving in a path alongside said identified path. 11. Warning system according to any one of the preceding claims and comprising comparator means for comparing a first signal derived from monitoring for the approach of an object along said identified path and a second signal derived from monitoring for the approach of an object in a comparator path which at least in part lies alongside said identified path. 12. Warning system according to claim 11 , wherein the first signal is derived from monitoring in a plane substantially parallel with a surface over which an approaching hazardous object is movable, and the second signal is derived from monitoring in an inclined direction which increases in distance from said surface with increasing distance from the detecting means. 13. Warning system according to claim 11 or claim 12, wherein operation of the warning means is a function of a difference between said first and second signals. 14. Warning system according to any one of the preceding claims, and comprising electronic discrimination means to inhibit operation of a warning signal in response to an approaching object of an inherently non-hazardous type. 15. Warning system according to any one of claims 11 to 14, wherein comparator means or discrimination means is operable to inhibit operation of a warning signal in response to environmental conditions including at least driving rain and vehicle spray. 16. Warning system according to any one of the preceding claims, wherein the detector means comprises an emitter operable to emit a beam along said identified path. 17. Warning system according to claim 16, wherein the emitter comprises a laser beam generator, radar beam, or radio frequency wave beam. 18. Warning system according to any one of the preceding claims wherein the detector means comprises an emitter which emits a beam having an operable height greater than operable width. 19. Warning system according to claim 18, wherein the beam has a height at least three times greater than width. 20. Warning system according to any one of the preceding claims, wherein the detector means comprises a receiver operable to receive a signal along said identified path. 21. Warning system according to claim 20, wherein the receiver is responsive to a reflected signal originated by one of a laser beam, radar or radio frequency radiation emitter or a thermal image signal received from an approaching object. 22. Warning system according to any one of the preceding claims, wherein at least a part of the detector means is positionable remote from the warning means. 23. Warning system according to any one of the preceding claims and comprising a plurality of detector means spaced along said identified path and each operable to monitor for an approaching object along a respective part of the length of the identified path. 24. Warning system according to any one of the preceding claims, wherein marker means in positionable remote from at least a part of the detector means at a position along said identified path, and homing means is provided whereby said part of the detector means is operable automatically to move to align with the marker means. 25. Warning system according to any one of the preceding claims, wherein at least one of the means for detecting an approaching object and the means for providing a warning indication is mounted on a vehicle. 26. Warning system according to any one of the previous claims, wherein at least one of the means for detecting an approaching object and the means for providing a warning indication is associated with a portable object. 27. Warning system according to claim 26, wherein the portable object is a road safety cone. 28. Warning system according to any one of the preceding claims, wherein a part of the system is remotely positionable and communication between parts of the system is achieved wirelessly. 29. Warning system according to any one of claims 1 to 25, wherein the means for detecting an approaching object and the means for providing a warning indication are substantially integral with one another. 30. Warning system according to claim 1 and substantially as described with reference to the accompanying drawings. 31. A road vehicle comprising in association therewith at least part of a warning system according to any one of the preceding claims. 32. Method of protecting road-side personnel working in the vicinity of an emergency vehicle comprising: providing said vehicle with detector means comprising an emitter operable to emit a beam of radiation reflectable by an on-coming vehicle, employing said detector means to detect reflection from an on-coming vehicle travelling along a path leading to said detector means and to discriminate against a reflected signal from a vehicle travelling outside said path, and in response to detection of another vehicle travelling along said path, to provide said personnel with a warning signal. 33. Method according to claim 32, wherein use is made of detector means and other means for providing a warning system according to an one of claims 1 to 30.

Inventors: JAMESON ARNOLD, JAMESON, ARNOLD
Applicants: JAMESON ARNOLD, JAMESON, ARNOLD
Application year: 1998
Main classification: G08G1
IPC codes: G01S7, G01S17, G08G1