METHOD OF DETERMINING OPTIMAL DETECTION BEAM LOCATIONS USING REFLECTIVE FEATURE MAPPING

Abstract: A method of determining the optimal positions of a plurality of detection energy beams (28) within a volume (26) of space under surveillance and used to detect the presence of an object (38) within such space comprises generating a set or map of reflection data corresponding to the points in said space where there is a high probability of detection. Each of a plurality of objects, such as vehicles (38), are successively displaced through the area under surveillance, and a set of sampling beams are trained on the object at each of a plurality of incremental positions to determine the distances, equatorial angle and azimuthal angle at which reflections from the object can be obtained. The recorded data provides a reflective feature map which can be used to determine the optimal number, placement and range of beams needed to reliably detect any of a plurality of objects, as in a collision avoidance system for vehicles.

Description: METHOD OF DETEBMDΪING OPTIMAL DETECTION BEAM LOCATIONS USING REFLECTIVE FEATURE MAPPING TECHNICAL FIELD The present invention generally relates to three-dimensional mapping techniques, and deals more particularly with a method of determining the optimal number and placement of a plurality of energy beams used to detect the presence of an object within a space under surveillance, using mapping techniques to determine the points in space where placement of a beam likely to result in detection of the object. BACKGROUND OF THE INVENTION Several technologies are known for use in detecting the presence of an object entering a volume of space under surveillance. These energy beams may comprise, for example, radio frequency energy (microwaves), sound waves (ultrasonics), or optical energy (e.g., infrared waves). One application of such technology involves collision avoidance systems used in on-the-road vehicles to detect the presence of an adjacent vehicle or object which poses a risk of collision. Each of the technologies mentioned above possesses certain advantages and limitations, but all of them present certain common problems in their implementation for a specific application. For example, such collision avoidance systems are typically employed to monitor a specific volume of space immediately adjacent the "host" vehicle to be protected. Energy having unique characteristics, e.g. wavelength, modulation frequency, etc., is projected from the host vehicle into the space, and reflections of this energy toward the host vehicle are monitored to detect the presence of a vehicle or other object presenting a risk of danger. However, cost, size and other constraints impose practical limits on the amount of energy that can be projected into the monitored space; therefore, it is necessary to project the energy in a limited number of energy beams which normally cover only a portion of the volume being monitored. Since only a limited number of energy beams may be employed in most collision avoidance systems, it is therefore important to judiciously choose the number, size and placement of the beams so as to maximize the likelihood of detection. This task is substantially complicated by several factors. For example, the size, geometry and features of the various vehicles which might enter the monitored zone vary widely, and therefore each present unique reflective characteristics. Also, adjacent curbing, road features and reflective road striping have the potential to reflect energy and therefore may result in false detections. On the other hand, the monitored volume of space must be sufficiently "covered" with beam energy so that smaller objects and vehicles, such as motorcycles and pedestrians, may be reliably detected. Accordingly, there is a need in the art for a method of determining the optimal number and positions of a plurality of energy beams employed to detect the presence of an object within a volume of space being monitored and particularly detection beams used in collision avoidance systems for vehicles. SUMMARY OF THE INVENTION It is a primary object of the present invention to provide a method for determining the optimal number and placement of a plurality of energy detection beams employed to detect the presence of an object, such as a vehicle within a volume of space under surveillance. A further object of the invention is to provide a method of the type described above which provides a set of data allowing selection of the number and placement of the energy beams in a manner to reliably detect any of a plurality of objects, such as vehicles, having differing physical features and geometrical configurations. A further object of the invention is to provide a method as described above which produces a map of the locations in the volume of space from which there is a high likelihood that beam reflections may be detected. According to one aspect of the present invention, a method of determining the optimal positions of a plurality of detection energy beams within a volume of space under surveillance comprises the steps of: (A) placing the object at a preselected position within the space; (B) directing a plurality of sample beams of energy from a source onto the object; (C) detecting the reflection of the sample beam energy from points on the object to a reference area; (D) recording the location in space of the points on the object from which the sample beam energy is reflected; (E) relatively moving the source of the sample beams and the object; and (F) repeating steps (B) through (D) to produce a spatial map of the locations in space from which the sample beam energy is reflected from the points to the reference area, the spatial map of reflection locations being related to the optimal spatial orientation of the detection beams required to relatively maximize the probability that the object will be detected by the detection beams. According to another aspect of the invention, a method is provided for determining the number and optimal positions of surveillance energy beams within a volume of space under surveillance and adjacent a host vehicle, where the energy beams emanate from the host vehicle and are intended to detect the presence of an adjacent vehicle within the space to avoid collision therewith. This method comprises the steps of: (A) directing a sample beam of energy into the space under surveillance from an area adjacent the space; (B) placing a vehicle to be detected within the space; (C) relatively moving the sampling beam and the vehicle to be detected to each of a plurality of relative positions in a manner such that the sampling beam impinges on different points of the surface of the adjacent vehicle and at different angles of incidence; (D) detecting the reflections of energy from the sampling beam which is incident on the adjacent vehicle; and (E) recording data related to each of the positions of the adjacent vehicle in the space when a reflection is detected, the recorded positions being related to the number and optimal positions of the surveillance beams. According to still another feature of the invention, a map of the locations and the volume of space from which energy waves are reflected to a reference area from points on an object which is successively disposed at each of a plurality of locations within the volume of space is produced by: (A) placing the object at a preselected position within the space; (B) directing a source of sample beam energy waves from the reference area onto the object within the space; (C) detecting the reflection of the sample beam energy waves from points on the object to the reference area; (D) relatively moving the beam source and the object; and (E) recording the locations in space of the points at which reflections of the sample beam energy waves are detected. The method is preferably carried out using a plurality of sample beams of energy, such as infrared optical energy. The source of the sample beams or the object under surveillance is moved in each of a plurality of linear, parallel paths so that reflections are sensed at a plurality of locations over the area under surveillance. For each relative position between the beam source and the object, the beam source is rotated about a substantially vertical axis to determine the reflections based on a plurality of angles of incidence. Similarly, the beam source is rotated about a substantially horizontal axis to each of a plurality of positions to determine the reflectivity of features on the object for each of the relative positions between the beam source and the object. The recorded data is employed to produce a composite map of the locations in space where reflections have been noted. The map of reflective features may then be used to determine the optimal number and placement of a limited number of detection beams. BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, wherein like reference numerals are employed to designate identical components and which are to be used in conjunction with the following description: Figure 1 is a plan view of a host vehicle equipped with a detection module forming part of a collision avoidance system and showing the approximate volume of space under surveillance; Figure 2 is a perspective view of the right side of the vehicle shown in Figure 1, and more clearly depicting the number and relative placement of the detection beams emanating from the detection module; Figure 3 is a rear elevational view of the host vehicle shown in Figure 1, depicted in operative relationship to an adjacent vehicle to be monitored; Figure A is a diagrammatic, plan view used to explain the method of the present invention; Figure 5 is a rear elevational view of a vehicle disposed within a volume of space under surveillance which is of aid in explaining the method of the present invention; Figure 6 is a front elevational view of apparatus employed to carry out the method of the present invention; Figure 7 is an elevational view of a portion of the side of a vehicle with a series of the sampling beams trained thereon, successively lower positions of the sampling beams being indicated in the phantom; Figure 8 is a diagrammatic, plan view showing the impingement of the sampling beams on the side of a vehicle; Figures 9-11 are reflective feature maps for a first vehicle, respectively representing the detection of reflections at various heights about the ground; Figure 12 is a map forming a composite of the maps of Figures 9-11; Figure 13-15 are reflective feature maps for another vehicle, respectively representing the detection of reflections at various heights about the ground; Figure 16 is a map forming a composite of the maps of Figures 13-15; and Figure 17 is a diagrammatic, plan view showing the optimal number and placement of a plurality of detection beams based on the reflective feature maps. TffiTATT.τm DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention generally relates to a method of determining the optimal number and placement of energy beams which are used to detect the presence of an object within a zone to be monitored. One such application of object detection requiring strategic placement of the energy beams is in the context of collision avoidance systems for vehicles, where it is desired to determine the presence of another vehicle, pedestrian or other object which is within a zone of danger relative to a protected vehicle and poses a risk of collision therewith. A typical collision avoidance system using multiple energy beams to detect adjacent objects is depicted in Figures 1-3. A tractor-trailer type vehicle is depicted which comprises a tractor or truck 24 that tows a long trailer 22. Large trucks of this type are typically referred to as "Class 8" trucks, and because of their size and configuration, the operator of such a vehicle normally has a relatively large blind spot within which an adjacent vehicle may be concealed from his view, thus presenting a severe hazard during lane-changing maneuvers, turns and the like. The collision avoidance system includes a collision avoidance detector 20 mounted on each side of the truck 54 and more particularly on the door 30 of the truck cab. The precise mounting location of the detector 20 will vary depending upon the nature, size and configuration of the truck or other "host" vehicle with which the detector 20 is used. In many applications, such as the truck 24, it may be unnecessary to employ a detector 20 on both sides thereof, and therefore only ' those energy beams 28 associated with the detector 20 on the right side of the truck 24 will be discussed herein. The detector 20 emits a plurality of beams 28 of energy forwardly, laterally and rearwardly into a volume of space 26 which comprises the zone to be monitored for the presence of vehicles, pedestrians or other objects posing a risk of collision with the truck 24. The energy beams 28 may comprise acoustical energy (e.g., ultrasonics), radio frequency energy (e.g., microwaves), or optical energy (e.g., infrared light waves). In the disclosed embodiment, nineteen of the beams 28 are employed to detect objects within the monitored zone 26. The zone 26 under surveillance is generally rectangular in plan view and is of a preselected height. The dimensions and geometry of the monitored zone 26 are such that the volume of space monitored is above the surface 26 of striping 32 on the road and extends laterally to a point which falls short of curbs 34, signs (not shown) or other objects which are not intended to be detected. The beams 28 emanate from the detector 20 and impinge upon objects, such as an adjacent vehicle 38 within the zone 26. A portion of the energy in the beam 28 is reflected from surface features such as the trim piece 40 on the adjacent vehicle 38, a portion of which energy is reflected in a beam 36 back to the detector 20. The spacing between, location, direction, size and number of the beams 28 must be carefully selected in accordance with a particular application to optimize system operation and to assure that all objects of interest within the zone 26 may be reliably detected. In some cases, it may be determined that certain of the beams 28, such as the lateral beam 28a and rearwardly projecting beams 28b, should extend between the normal monitoring zone 26 in order to detect certain unique surface features of adjacent vehicles such as trim components, license plates or the like. In any event, it is important to use a relatively minimum number of the beams 28 to provide the required degree of detection reliability, since the use of additional beams is unnecessarily costly and may not significantly add to detection reliability. The present invention is therefore concerned with determining the number and optimal placement, positioning and length of the beams 28 so as to assure high detection reliability at minimum cost. Attention is now directed to Figures 4-8 which depict an arrangement for carrying out a novel method of determining the optimal position, placement, length and number of the beams 28. First, an envelope shown in solid line and designated by the numeral 56 in Figure 4 is determined, which defines the area in plan view where it is desired to detect objects which might pose a risk of collision with the host vehicle 24. The envelope 56 essentially possesses a configuration in plan view similar o identical to the zone 26 shown in Figure 1. A source of sampling beam energy 42 is positioned at a point adjacent the detection envelope 56, essentially corresponding to the point on the host vehicle 24 where the detection unit 20 would ordinarily be mounted (see Figure 1). In one suitable embodiment, the sampling beam source 42 produces six horizontally aligned beams 66 of energy, for example, optical energy of the infrared wavelength. Four of such beams 66a-66d are depicted in Figure 7 as impinging on the door of an adjacent vehicle 38. In the present embodiment, the beams 66 are of circular cross-section and, as shown in Figure 8, impinge upon the side of the vehicle 38 as contiguous or closely adjacent circular spots HOa-llOf. For purposes of carrying out the method of the present invention, the detection envelope 56 is divided by sector lines 58-62 into four sections respectively subtended by essentially equal angles A-D. The sampling beam source 42 is shown in more detail in Figure 6. Two sets of three horizontally aligned light-emitting diodes (LED) are respectively mounted behind lenses 74, 76 on optical supports 70, 72. Two sets of three photodetectors 84 are likewise motinted behind lens 80, 82 which are disposed on the optical mounts 70, 72. Thus, each set of LEDs 78 are respectively associated with the photosensors 84 carried by the same optical mount 70, 72. The precise aiming of the LEDs 78 and photosensors 84 may be controlled by any suitable means such as micrometer adjustments 86. The optical mounts 70, 72 are respectively secured to bases 88, which in turn are independently pivotally mounted for rotation on pivot pins 90 about substantially vertical axes on a common support assembly 94. The support assembly 94, in turn, is mounted on a base 96 which may be rotated about a substantially vertical axis 106. The base 96 is coupled by a joint 98 to a bearing assembly 100 which is rotatable about a substantially horizontal axis 104. The bearing assembly 100 is in turn mounted on a suitable support 102. It may thus be appreciated that the optical mounts 70, 72 may be rotated about their vertical axes to achieve alignment between the two sets of respectively associated horizontal beams, and rotation about the horizontal and vertical axes 104, 106 allows precise aiming of the horizontal bank 66 of six beams to specific areas within the detection envelope 56. More particularly, it can be appreciated that the bank of six horizontal beams may be pivoted about a vertical axis in the direction of arrow 64 (Figure 4) to any of a plurality of indexing positions through an angle which will be referred to herein as the "equatorial" angle. Likewise, it may be appreciated that the bank of six beams 66 may be rotated about a horizontal axis 104 in the direction of arrow 65 (Figure 5) to any of a plurality of second index positions through angles which will be referred to herein as "azimuthal" angles. After the beam source 42 is disposed in the proper position adjacent the envelope 56, it is rotated about a vertical axis to one of the sectors, such as sector D, at a given azimuthal angle. For example, as shown in Figure 5, the first azimuthal angle may correspond to the level indicated by the numeral 1, so that the beams effectively illuminate upper portions of the vehicle 38. With the beam source 42 positioned at the first combination of equatorial and azimuthal angles, the vehicle 38 is moved along a first track 40 designated as track 1 to a first position where a portion thereof, for example, is within sector D. With the beam source 42 aimed at sector D, the LEDs 78 are pulsed to produce horizontal bank of beams 66. Those of the beams 66 which are incident on the surface of the vehicle 38 result in illumination spots, such as those designated by the numerals HOa-llOf in Figure 8. Depending upon the geometry and nature of the surface features thusly illuminated, a portion of -li¬ the incident energy will be reflected back toward the beam source 42 and is picked up by the photosensors 84. In other words, those particular illuminated surface features on the vehicle 38 which are disposed at certain angles relative to the beam source 42 reflect the incident beam at the proper angle back toward the beam source 42 so that the beam source 42 effectively "sees" or detects such reflective feature or surface area. The precise location in space of each such reflection produced by a surface feature is recorded for each of the tracks 40 (1-7). The precise points in space where such reflections occur can be determined using any of various known techniques, including triangulation. Normally, for future use, the reflection locations are recorded in the form of an x, y, z coordinate system, along with the equatorial and azimuthal angles of the beam source 42. After the first set of data is recorded in the manner just described, the beam source 42 is rotated about its vertical axis to view the next sector, which in this case is sector C, while the vehicle 38 remains at its first incremental position in track 1. At this point, a second set of reflective data is taken, following which the beam source 42 is successively moved to view sectors B and A where similar sets of reflection data are recorded. After the beam source has been rotated through each of the sectors A-D for a given azimuthal angle, the beam source 42 is rotated to a second azimuthal angle so as to view, for example, that portion of the vehicle 38 at a lower elevation designated by the numeral 2. The beam source 42 is then successively indexed to differing equatorial angles to view sectors A-D for the second azimuthal angle, and the reflection data is recorded for each combination of these equatorial and azimuthal angles. In a similar manner, this same recording process is carried out for each of the additional azimuthal angles, which correspond to elevations 3 and 4 in Figure 5, where the beam source 42 is swung about its vertical axis to permit recording of reflection data in each of the four sectorε A-D. Following the recording of such data, the vehicle 38 is then moved forwardly in track 1 to a second incremental position, where a second set of reflection data is recorded in the manner just described. It may be readily appreciated that this second set of reflection data may very well be different than the first set thereof since, due to the incremental movement of the vehicle 38, the angle of incidence on the various reflective features of the vehicle 38 is slightly changed. For example, as shown in Figure 8, the vehicle 38 is disposed at a particular position of incremental movement where a particular surface feature designated by the numeral 114 is coincidentally disposed at an angle substantially perpendicular to rays 116 of the beam 66d. As a result, the rays 116 incident on surface feature 114 are reflected back toward the beam source 42 and are detected by the corresponding photosensor 84 as a reflection. In contrast, it may be seen that the rays, e.g. 112, of the other beams 66a, 66b, 66c, 66e, 66f are incident on surface features which are inclined relative to the beam source 42 at an angle such that the incident light energy is reflected in a direction which prevents detection thereof by the photosensors 84. Figure 7 illustrates the alignment of the bank of beams 66 along a substantially horizontal axis 108, four of such beams 66a-66d being shown incident on the door of the vehicle 38. From this figure, it may be seen that beam 66d is incident on the door handle 106 of the vehicle 38 which may possess surface areas of various angular dispositions that may increase the likelihood that a portion of the energy in beam 66d is reflected back toward and is detected by the corresponding photosensor 84. The successively lower elevational positions of the beam bank are designated by the numerals 2, 3 and 4 in Figure 7, these elevational positions being determined by the azimuthal angle of the beam source 42. It may be readily appreciated that the reflection data determined in the manner described above can likewise be recorded by other techniques and sequences of relative movement between the beam source and the vehicle 38. For example, the vehicle 38 may remain stationary, and the beam source 42 may instead be moved to successive positions in a plurality of linear paths at successively greater lateral distances from the vehicle 38, and in this manner, a set of data would be produced which is identical to that previously described. Indeed, it may be preferably to linearly move the beam source 42 to successive incremental positions, rather than the vehicle 38, since the beam source 42 could easily be mounted on apparatus which can be more precisely indexed and displaced in comparison to the vehicle 38. Likewise, the " sequence of indexing the beam source 42 to various azimuthal and equatorial angles could be altered. For example, for a given incremental position of the vehicle 38, the beam source 42 might be rotated to successive azimuthal positions for each selected equatorial position. It is only necessary that there be the required relative movement between the beam source and the vehicle 38 so as to determine the precise points in the envelope of space 56 at which reflections are obtained from various surface features on the vehicle 38. After a set of reflection data is obtained for a vehicle 38 of a given configuration, the process is repeated to obtain a second set of data for a vehicle of a differing configuration. This is necessary since the reflective features of vehicles differ depending upon the physical geometry, size and choice of materials used in the vehicle. It is known, however, that certain types of vehicles possess surface geometries which are more difficult to detect than others. Accordingly, it is preferable to select those vehicles having the surface features which are most difficult to detect for use in generating reflection data which is subsequently used to determine the number and displacement of sampling beams. Having generated the necessary sets of data, such data can be plotted to effectively provide a map of the points in the envelope space 56 at which "detections" may be obtained for a given vehicle model. For example, Figures 9-12 are plots or "maps" of detections for a 1988 Pontiac Fiero which is black in color. The ordinate depicts the lateral distance from the beam source 42, which of course corresponds to the lateral distance from the detector 20. Also, it can be appreciated that the vertical plots are divided into seven tracks which correspond with the lateral, parallel tracks 40 shown in Figure 4. The abscissa is a plot of the distance from the beam source 42 (or detector 20) in a direction forward up to the leading edge of the envelope 56 (or zone 26) which is indicated as a vertical, dotted line. These plots are based on a four-level gray scale, with the totally white spaces indicating no-detects and the totally dark portions indicating four or more detects at any given x-y position. Figures 9-11 respectively correspond to the data recorded for three different elevational (azimuthal) positions, with Figure 9 being the lowest position, Figure 10 being at a middle position, and Figure 11 being at an uppermost elevational position. It can be seen in Figure 9 that the low beams fail to detect the vehicle at the upper left region of the zone due to the fact that they are aimed under the rear bumper at long ranges. It can also be seen that there is a strong area of response beyond the leading edge of the zone (vertical dash line) due to the very high reflectivity of the rear license plate of the vehicle. Figure 10 shows that the middle height beams fail to detect the "test" vehicle in some parts of the middle zone because they sometimes all fall on highly reflective body panels at unfavorable angles of incidence. Again, there is a substantial response forward of the leading edge of the zone due to the high reflectivity of the license plate of the test vehicle. Figure 11 demonstrates that the highest position of the beams are useful mainly for detecting at the outer lateral boundaries, as well as at relatively close distances, particularly near the beam source (or detection unit 20). Figure 12 is a detection map which forms a composite of those shown in Figures 9-11, showing the detection responses for all of the beams at all of the chosen azimuthal elevations for the forwardmost sector of the envelope of volume 56. From Figure 12, it was determined that a subset of only ten of the total number of thirty-six beams that were used to generate the reflection data were needed to effectively cover the forward quadrant and could do so with less undesired response resulting from the highly reflective areas of the test vehicle forward of the leading edge of the zone being monitored. Figures 13-15 are similar to Figures 9-11 but depict the detection data for a 1988 Ford EXP which is black in color. Figure 13 shows that, compared with the Fiero, there is less response at long ranges, due apparently to the relatively high position of the license plate on the Ford EXP. All of the beams fall under the plate at long ranges. Figure 14 shows that there is less response at the longer lateral distances compared to the Fiero, most probably due to the absence of reflective trim or side reflectors on the Ford EXP. Figure 15 shows that the higher beams used to generate the detection data in this particular map are sufficiently high in elevation to detect the comparatively high license plate of the Ford EXP forward of the leading edge of the detection zone. Figure 16 is a map of the detection responses which is a composite of the maps of Figures 13-15. From Figure 16, it can be concluded that the set of ten beams which were effective for detecting Fiero are likewise very effective for detecting the Ford EXP. Using the recorded test data and detection maps such as those described above, the final number, positioning and length of the sampling beams may be determined. A typical set of such beams indicated by the numeral 28 are shown in Figure 17. Figure 17 depicts the relative angles of the beams as well as their heights and lengths. From the foregoing, it may be appreciated that the method of the present invention not only provides for the reliable accomplishment of the objects of the invention, but does so in a particularly effective and economical manner. It is recognized, of course, that those skilled in the art may make various modifications or additions to the preferred embodiment chosen to illustrate the invention without departing from the spirit and scope of the present contribution to the art. Accordingly, it is to be understood that the protection sought and to be afforded hereby should be deemed to extend to the subject matter claimed and all equivalents thereof fairly within the scope of the invention.

Claims: CLAIMS 1. A method of determining the optimal positions of a plurality of detection energy beams within a volume of space under surveillance and used to detect the presence of an object within said space, comprising the steps of: (A) placing said object at a preselected position within said space; (B) directing a plurality of sample beams of energy from a source onto said object; (C) detecting the reflection of said sample beam energy from points on said object to a reference area; (D) recording the location in said space of the points on said object from which said sample beam energy is reflected in step (B) ; (E) relatively moving said source of said sample beams and said object; and, (F) repeating steps (B) through (E) to produce a spatial map of the locations in said space from which said sample beam energy is reflected from said points to said reference area, the spatial map of reflection locations being related to the optimal spatial orientation of said sampling beams required to relatively maximize the probability that said object will be detected by said detection beams. 2. The method of Claim 1, wherein step (B) is performed by: simultaneously training a group of said sample beams onto said object, and angularly displacing said group of said sample beams about a reference axis to each of a plurality of angular positions, and repeating steps (C) and (D) at each of said angular positions. 3. The method of Claim 1, wherein step (E) is performed by linearly displacing one of said source of said sample beams and said object to each of a plurality of sampling positions, there being a set of said sampling positions corresponding to each of said angular positions of said object. 4. The method of Claim 1, wherein step (E) is performed by linearly displacing one of said source said sample beams and said object relative to the other along a first reference path. 5. The method of Claim 4, wherein step (E) includes relatively displacing said source of said sample beams and said object in a direction traverse to said first reference path to each of a plurality of transversely spaced apart locations, and linearly displacing one of said source and said object respectively along each of a plurality of reference paths extending parallel to said first path, wherein said plurality of reference paths respectively extend through said plurality of transversely spaced apart locations. 6. The method of Claim 1, wherein step (E) is performed by angularly displacing said source of said sample beams to each of a plurality of angular positions. 7. The method of Claim 6, wherein said source is angularly displaced about a substantially horizontal reference axis such that said sample beams are directed onto said object at a plurality of different elevations respectively associated with said angular positions. 8. The method of Claim 7, wherein step (E) further includes linearly displacing one of said source and said object along a preselected path for each of said angular positions. 9. A map of the locations in a volume of space from which energy waves are reflected to a reference area from points on an object which is successively disposed at each of plurality of locations within said volume of space, produced by: (A) placing said object at a preselected position within said space; (B) directing a source of sample beam of energy waves from said reference area onto said object within said space; (C) detecting the reflection of said sample beam energy waves from points on said object to said reference area; (D) relatively moving said beam source and said object; and (E) recording the locations in said space of the points at which reflections of said sample beam energy waves are detected in step (C). 10. The map of Claim 9, wherein step (D) is performed by linearly displacing one of said beam source and said object along a reference path. 11. The map of Claim 10, wherein step (D) includes displacing one of said beam source and said object in a direction transverse to said reference path to each of a plurality of transverse locations. 12. The map of Claim 9, wherein step (D) is performed by linearly displacing one of said beam source and said object successively along each of a plurality of parallel spaced apart paths. 13. The map of Claim 9, wherein step (D) is performed by rotating said beam source about a substantially vertical axis to each of a plurality of first angular positions. 14. The map of Claim 13, wherein step (D) includes rotating said beam source about a substantially horizontal axis to each of a plurality of second angular positions. 15. A method of determining the number and optimal positions of surveillance energy beams within a volume of space under surveillance and adjacent a host vehicle, said energy beams emanating from said host vehicle and intended to detect the presence of an adjacent vehicle within said space to avoid collision with said adjacent vehicle, comprising the steps of: (A) directing a sampling beam of energy into said space under surveillance from an area adjacent said space; (B) placing a vehicle to be detected in said space; (C) relatively moving said sampling beam and said vehicle to be detected to each of a plurality of relative positions in a manner such that said sampling beam impinges on different points of the surface of said adjacent vehicle and at different angles of incidence; (D) detecting the reflections of energy from said sampling beam which is incident on said adjacent vehicle; and (E) recording data related to each of the positions of said adjacent vehicle in said space when a reflection is detected in step (D), the positions recorded in step (E) being related to the number and optima positions of said surveillance beams. 16. The method of Claim 15, wherein said area adjacent said space corresponds to the location where said surveillance beams emanate from said host vehicle. 17. The method of Claim 15, wherein step (C) is performed by moving said adjacent vehicle successively along each of a plurality of parallel, linear paths. 18. The method of Claim 15, wherein step (C) is performed by moving said sampling beam successively along each of a plurality of parallel, linear paths. 19. The method of Claim 15, wherein step (C) includes rotating said sampling beam about a substantially vertical axis to each of a plurality of rotational positions at which data is recorded in step (E). 20. The method of Claim 15, wherein step (C) includes the step of rotating said sampling beam about a substantially horizontal axis to each of a plurality of rotational positions at which data is recorded in step (E). 21. The method of Claim 15, including the step of simultaneously directing a plurality of sampling beams of energy into said space under surveillance from said adjacent area, and step (D) includes detecting the reflections of energy from each of said sampling beams. 22. The method of Claim 15, including the step of forming a spatial map of locations in said space where reflections are detected in step (D). 23. The method of Claim 22, including the step of selecting the number and optimal positions of said surveillance beams based on information contained in said spatial map. 24. The method of Claim 15, wherein steps (A) through (E) are repeated for each of a plurality of vehicles, and said method includes the step of selecting the nvimber and optimal positions of said surveillance beams required to detect the presence of any of said plurality of vehicles within said adjacent space. 25. A spatial map of the location in said space at which reflections are detected in step (D).

Inventors: JUDS SCOTT, MATHEWS PAUL, JUDS, SCOTT, MATHEWS, PAUL
Applicants: AUTO SENSE LTD, AUTO-SENSE, LTD.
Application year: 1991
Main classification: G08B29
IPC codes: G08G1