TECHNICAL FIELD

[0001] The present invention relates to apparatus for and a method of counting objects, particularly people, including establishing a direction of movement, along a predefined path. While the field of this invention relates primarily to counting people, it can equally apply to other inanimate objects,

BACKGROUND TO THE INVENTION

[0002] Object and people detection and counting, including determining direction of movement of the object or person, is a useful measure and is often in demand in factories, and other commercial environments. Many methods of achieving this are known and used including cameras, infrared sensors to detect body heat, and light beams. Horizontally directed light beams broken b passage of a person or object are used but can provide some problems including being adversely affected by atmospheric light conditions and difficulties with giving false readings if two persons or objects break the beam more or less simultaneously. Scanning lasers providing a vertical scanning plane are also used to count people passing along a predetermined path. The advantage of utilizing scanning lasers is that they are immune to lighting effects and ambient conditions.

[0003] One known method utilising scanning lasers is to utilise two sensors each comprised of a scanning laser or at least two scanning planes. The reason for using two sensors is that the triggering of both sensors provides redundancy in sensing and reduces failed positive counts. Moreover, the order of triggering can be used to determine direction of movement of the person or object. Two scanning planes may be created with two sensors or with one sensor using one or more mirrors to reflect an unused portion of the scanning plane from the one sensor so as to create two parallel vertical planes through which the person or object passes. As the object or person successively passes through these two planes, each plane senses an incursion and it is the incursion, and the order of the incursions that determines the object or person's presence and the direction of movement.

[0004] The disadvantage with using two scanning planes is that it requires two sensors or one sensor with a complicated mirror configuration to split the scanning plane into two scanning planes,

[0005] The objective of the present invention is to provide an object or person counting arrangement of the aforementioned kind that is effective in use utilising a single scanning laser producing a single scanning plane that can count the passage of persons or objects and determine their direction of movement without the need of spaced scanning planes or other additional means.

[0006] in the following the word "item" in the context of referring to something being counted, is used generically to refer to persons, animals or inanimate objects in any desired counting arrangement or configuration.

SUMMARY OF THE INVENTION

[0007] The present invention provides, in one aspect, apparatus to count and determine a movement direction of items moving along a predefined path, said apparatus including a scanner being a scanning laser range finder with a sensor emitting a sweeping scan beam in a single scanning plane, said scanner further being capable of repeating said complete scan to form repeated multiple said complete scans of said single scanning plane, said scanner, in use, being disposed to locate said single scanning plane transverse to said predefined path such that said items moving along said predefined path pass through said single scanning plane, said single scanning plane further forming an acute angle with a surface region of each said item moving along said predefined path, such that the sensor, when the scanning plane is broken by a said item, senses spaced positions on said surface region as the item moves along the predefined path, said spaced positions being used by a computer based evaluation means to count said item and to establish a movement direction of said item.

[0008] Conveniently, an uppermost point or edge of said single scanning plane is located at a height above items expected to be moving along the predefined path, the single scanning plane extending downwardly from said uppermost point or edge. Alternatively, the lowermost point or edge of said single scanning plane is located below items expected to be moving along the predefined path, the single scanning plane extending upwardly from said lower most point or edge. In a still further alternative arrangement, the single scanning plane may extend from a position transversely disposed of said predefined path and generally across said predefined path. Conveniently, the sensor determines movement of each item in either a forward or an opposite direction.

[0009] Preferably the single scanning plane forms an angle with said predefined path at said predefined path of between 0° and 90°. Preferably said angle is 90°. Conveniently, the single scanning plane forms an acute angle with a line extending at 90° from said predefined path to said scanning laser range finder. The aforesaid acute angle with a line extending at 90° from the predefined path may be between 3° and 20°, preferably between 10° and 1 _. 5°, and more preferably about 12°.

[0010] In accordance with a further aspect of this invention, a method is provided of counting and determining a direction of movement of an item moving along a predefined path, said method including positioning a scanner being a scanning laser range finder adjacent said predefined path, the scanner, in use, emitting a sweeping scanning beam in a single plane to form one complete scan of the single scanning plane and thereafter repeating said complete scans of said single scanning plane to form repeated multiple said complete scans of said single scanning plane, said positioning of the scanner also including disposing the scanner to locate the single scanning plane traversing said predefined path such that the single scanning plan forms an acute angle with a surface region of an item moving along the predefined path, the sensor of said single scanning plane forming a sensible movement direction on said surface region as the item moves along said predefined path indicative of a movement direction of said item, and further providing computer based evaluation means to receive inputs from said sensor indicative of a said item passing through the single scanning plane and of the sensible movement direction on said surface region to thereby count the number of said items and establish the movement direction along the predefined path of each said item.

[001 1 ] The predefined path may be substantially a I ine or alternatively could have a substantial width provided that the single scanning plane can scan across the desired width.

[0012] Preferably, the single scanning plane is disposed in an upright direction and forms an acute angle with said predefined path, said acute angle being between 75° and 80°. Conveniently, the acute angle is about 78°.

Preferably, at the level of the predefined path said single scanning plane traverses the predefined path at right angles. In another possible method, the scanning laser range finder might be located laterally of the predefined path and the single scanning plane extends transversely across said predefined plane.

[0013] The invention will be better understood from the following description given in relation to the accompanying drawings illustrating preferred embodiments of the invention. In the following description reference will generally be made to the items being counted as people typically choosing to walk or otherwise move along a predefined path, however, it will be understood that other things, both inanimate and animated can be counted by the apparatus and method of this invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Fig 1 is a diagrammatic view of a known prior art arrangement wherein the scanning plane of the scanning laser range finder is disposed vertically;

[0015] Fig 2 is a similar diagrammatic view with the scanning laser range finder disposed in accordance with the present invention;

[0016] Fig 3 is a diagrammatic view of people moving in a predefined direction with the scanning laser range finder positioned above the people and disposed similarly to Fig 2;

[0017] Fig 4 is a diagrammatic view of objects moving in a predefined path with the scanning laser range finder positioned below the objects; and

[0018] Fig 5 is a graphical representation of the intersection of the single scanning plane with a person or object moving in a first direction along the predefined path against time of movement of the person (or object).

DESCRIPTION OF PREFERRED EMBODIMENT

[0019] Fig 1 diagram matically illustrates a predefined path 10 along which people (or objects) may move in a forward or first direction being indicated by the arrowhead. The scanner 1 1 , typically a scanning laser range finder, is positioned above the predefined path and directs a scanning beam downwardly to swee a scanning plane 1 that will be broken by a person moving along the predefined path in either direction. The scanning plane 1 is typically disposed vertically, that is the angle Θ is at 90° to the predefined path. Normally the scanning plane 12 defines a line 13 at the level of the predefined path that also forms an angle with the predefined path of 90°. An evaluation unit 14 is provided to receive signals of the information sensed by the scanner 1 1 , however, the scanner 1 only senses the number of times the scanning plane 12 is broken by people moving in either direction (forward or in an opposite direction) and cannot, of itself determine a direction of movement of the person breaking the scanning plane. If direction of movement is also a desired piece of information that needs to be monitored, then further sensing apparatus needs to be installed and used as previously described.

[0020] Fig 2 diagrammatically illustrates apparatus and a method of operation of a scanning device and processing equipment according to the present invention. Like reference features in Fig 1 have been given the same reference numerals. In Fig 2, the scanner 30 is typically an LMS family of sensors made by Sick AG including model types LMS, TIM and LD-OEM. Equivalent types of scanners made by other manufacturers might also be used. These sensors are described as scanning laser range finders and they are capable of producing a sweeping laser beam passing through a single scanning plane 31 to sense an object that may break the scanning plane 31 , The sweeping laser beam repeats itself in rapid succession to provide a continuous sensing and evaluation of anything that may break the scanning plane 31 and generate distance and angle measurements of objects intersecting the scanning plane 31 from the reference point of the sensor. As shown in Fig 2, the single scanning plane 31 is disposed at an acute angle Θ that is less than 90° to the direction of the predefined path 10. The angle Θ may typically be 70" to 87° preferably between 75° and 80°. The scanner 30 sets the scanning plane 31 at an angle of 3° to 20°, preferably 10° to 15° to an imaginary vertical line 15 that passes through the scanner and is disposed at an angle Ϊ of 90° to the predefined path 10. The line 13 of the single scanning plane 31 intersecting the predefined path 10 may form an angle a of 90° with the predefined path 10 or any angle between 0° and 90°.

[0021] Fig 3 represents a series of objects or people 16, 17, 18, 19 and 20 moving along a predefined path 10 in a first direction of travel indicated by arrow 21. The object / person 19 is shown, over a time interval, in three positions, the first bein in full outline (a) and the second and third positions, in broken outline (b) and (c). The single scanning plane 31 is broken by engagement of the surface region 32 of the object / person 19 as it moves in direction 21 along the path 10. The height along the axis h of the intersection of the scanning beam 31 with the surface region 32 is shown at 33, 34 and 35 for positions (a), (b) and (c) respectively. In Fig 3, the sensor 30 is positioned above the objects people moving along the path 10. Fig 4 represents diagrammatically a similar arrangement but where the scanner 30 ^' is positioned below the objects. Fig 5 is a graphical repreeentation of the sensed or scanned points 33, 34 and 35 indicating a relative increase in the vertical component of the intersection points caused by the intersection of the scanning plane 31 over successive scans. Of course, if the object / person were moving in the opposite direction (arrow 22), then there would be a relative decrease in the vertical component of the intersection points. The predominant relative increase or decrease in the vertical component of the scanning plane intersection points over successive scans determines the relative direction of travel of the object / person.

[0022] The predominant relative increase or decrease in the vertical component of the intersection point caused by the intersection of the object / person with the scanning plane 31 over successive scans is calculated by software connected to the scanner (scanning laser range finder) 30 and residing in an evaluation unit 40. The evaluation unit may be integrally part of the scanner 30 or provided separate to the scanner 30 but receiving sensed information from the scanner.

[0023] The scanner 30 may be positioned directly above or below the predetermined path 10 or transversely spaced from but generally above (or below) the predefined path 10. The scanning plane 31 should, however, at least traverse the predefined path 10. In another possible arrangement, the scanner 30 might be positioned to either side of the predefined path.

Other variations and/or modifications will be apparent to those skilled in this art falling within the scope of the annexed patent claims.