WO1993023799A1

WO1993023799A1 - A control system for gates

Info

Publication number: WO1993023799A1
Application number: PCT/SE1993/000433
Authority: WO
Inventors: Einar Edland; Roland Wängelin
Original assignee: Metallteknik Met-O-Matic Ab
Priority date: 1992-05-15
Filing date: 1993-05-17
Publication date: 1993-11-25
Also published as: SE9201556D0

Abstract

The present invention relates to a system for controlling entrance gates to store localities in particular or to other localities open to the public. The entrance system includes an entrance passageway which is defined by posts on which gates are pivotally mounted. A sensor means functions to detect the presence of people and objects in the vicinity of the passageway and to deliver signals to a control means for controlling opening and closing of the gate. The sensing means includes at least one sonar (8, 9) which is mounted in or in the vicinity of the passageway (2) and which comprises a transmitter/receiver means for transmitting ultrasonic pulses and receiving ultrasonic pulses that are reflected from objects and persons located within the defined measuring area.

Description

A CONTROL SYSTEM FOR GATES

FIELD OF THE INVENTION

The present invention relates to a system for controlling gated entrances, preferably gated entrances which permit access to retail stores or other localities open to the public. The entrance control system includes an entrance passageway which is defined by posts on which rotatable or pivotal gates are mounted, and a sensor which detects the presence of people and objects in the vicinity of the passageway and sends signals to a control arrangement which functions to control opening and closing of the gate.

BACKGROUND OF THE INVENTION

Different types of entrance systems which include openable and closable gates are used at the entrances to retail stores. These entrance systems function to control the flow of customers into the store, by forcing the customers to pass through a defined passageway. The entrance system also functions to prevent customers from exiting through the passageway without passing a pay desk, either consciously or by mistake. The entrance system is thus constructed to permit one-way passage into the store, while preventing customers leaving the store through the entrance passage.

The openable and closable gates may be constructed to keep the passageway closed when in a normal closing position, and to be openable, either manually or automatically, to allow people to enter the store, while latching the gates in the opposite, exit direction. Alternatively, the gates may be constructed to remain open in a normal gate position, and to close automatically should a person attempt to exit the store through the entrance passageway. Opening and closing of the gates is thus controlled by control equipment which detects locally the presence of customers and also objects, in certain cases.

It is known in this connection to construct sensor systems with the aid of photocells that are placed at a given distance in front of and behind a gate. This system is only able to detect when a person or an object breaks the light beam projected across the passageway and therewith indicate that an object is located in the beam path. This system is thus unable to indicate the direction in which the person or object moves. However, this problem has been solved by arranging a number of photocells in a lattice or grid pattern in different positions relative to the gate. By combining the signals delivered from respective photocells, it is possible to gather information, relating to the direction in which an object or person moves. This solution is expensive and it is necessary to mount the photocells in separate devices both in front of and behind the gates, which prevents the provision of free areas on both sides of the gates. Unfortunately, it is also necessary to place the sensitive photocells and reflectors in functional positions in which they are also exposed to the risk of damage from shopping trolleys or carts, and the like.

Also known to the art are systems which use infrared detectors (IR detectors) which detect temperature changes in the sensing area. One drawback with this system, however, is that it is only able to detect changes that lie in a specific frequency range, i.e. temperature differences which lie within the measuring range of the sensor. Thus, while a person who moves within this measuring range will be detected, a stationary person or object at room temperature, for instance a shopping trolley, cart, etc., will not be detected. The system can thus be readily "fooled", by standing still in the measuring range for a given period of time, or by pushing an object in the wrong direction out through the system. Difficulties have also been encountered in operating the system with solar lighting, for instance.

It is also known to use radar technology in the present connection, in which movements are detected with the aid of electromagnetic microwaves and automatic impulse emitters. Besides being expensive, a system of this kind does not function satisfactorily because of its sensi¬ tivity to disturbances, which is due to the great range of the disturbance sources that lie within the frequency band concerned.

It is also known, for instance from US-A-4,628,496, to use ultrasonic pulses for detecting the presence of per¬ sons and objects in a space. These known systems, however, are complicated and include a system of mutually coacting, ceiling-mounted sonars. The system is intended to prevent unauthorized persons passing through a normal¬ ly locked door arrangement but permitting authorized persons to pass therethrough. The system is thus not suited to solve those particular problems that are fundamental to the present invention.

SUMMARY OF THE INVENTION

The object of the present invention is to solve the aforesaid problems by providing an entrance system which is proof against disturbances and which cannot be "fooled", is of simple construction and includes only a small number of expensive units and is therefore inexpensive. Another object of the invention is to provide an entrance system which will satisfy all security requirements placed on systems of this kind. These objects are achieved in accordance with the invention by means of an entrance system which includes a sensing arrangement that includes a sonar means which detects the presence of persons and objects in the vicinity of the entrance passageway, by transmitting ultrasonic pulses from the sonar.

An entrance system of the kind defined in the intro¬ duction is characterized by the novel features set forth in Claim 1.

Further advantageous characteristic features of the invention will be evident from the following description of exemplifying embodiments of the invention and also from the subordinate Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to the accompanying drawings, in which

- Figure l illustrates a first embodiment of an in¬ ventive entrance system, as seen from outside the entrance;

Figure 2 illustrates the entrance system of Figure 1 as seen from inside the entrance;

- Figure 3 is a principle diagram of a sonar unit, in accordance with the invention;

Figure 4 is a block diagram which illustrates the sonar unit of Figure 3;

- Figure 5 is a flowsheet which describes the control system according to one embodiment of the invention; and - Figure 6 is a block diagram which illustrates the gate system according to one embodiment of the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Figures l and 2 illustrate an inventive store entrance system, comprising an entrance opening 2 whose width is sufficient to enable shopping trolleys, children's carriages (prams) and the like to easily pass through. Placed on each side of the entrance opening are double gateposts 4 which support pivotal gates 6. In the case of the illustrated embodiment, the gates 6 are normally swung-out across the width of the opening, so as to prevent passage through the gates 6 until the gates are activated.

One or more sensing devices are mounted at a suitable location in or in the vicinity of the entrance passageway 2, such as to detect the presence of persons and objects in the areas in front of and behind the gates. In the case of the Figure l embodiment, a first sensing device 8 is mounted in a front gatepost 4, while a second sensing device 9 is mounted in a rear gatepost 4. The sensing devices are positioned so as to be face generally towards the permitted movement direction of arrow A or in the same direction as arrow A.

The .inventive sensing device is comprised of a sonar (sound navigation and ranging) , which is constructed to function as both a transmitter and a receiver of ultrasonic signals. The sonar transmits signals or pulses at a frequency within the ultrasonic frequency range, these signals being reflected and transmitted back to the sonar when impinging on an object. One characteristic feature of sonar signals is that the transmitted signal spreads and diverges in the form of a lobe. According to the invention, the signals are transmitted in the form of ultrasonic pulses that have a duration of preferably about 250 μs and with high energy content, i.e. the pulse or signal has a voltage of about 120-350 V analogously. The receiver in the sonar is selective, i.e. it will react solely to signals which lie within its own frequency range, meaning that signals which lie within other frequency ranges are filtered-out. The high energy content of the signal enables the sonar receiver to be insensitive, meaning that the receiver will not sense disturbances from ambient signals that have low energy contents. This construction renders the sonar insensitive to ambient disturbances.

The sonar transmits sonic pulses and when the pulses impinge on an object, an echo is transmitted back to the sonar and captured in the sonar receiver. The sonar is tuned to sense the echo within a given measuring range in the entrance passageway and sorts-out echoes from objects that lie outside this range. According to the invention, the sonar is permitted to receive several sequential echoes from the object before sensing takes place, so as to exclude false echoes.

The direction in which the object/person moves is determined by repeated echoes which change in time.

Movement of an object is determined by comparing the time of reflected signals at intervals of about 5-100 ms. When the echo time shortens between these intervals, it signifies that the object is moving towards the sensing arrangement, whereas lengthened echo times signify that the object is moving away from said arrangement.

The pulse captured in the sonar is processed in an electronic unit, in which the pulse is amplified, among other things, and then delivered to a microprocessor. The microprocessor incorporates those working areas, so- called windows, within which the sensing devices are intended to operate or to detect the echoes, and the signals delivered by the sonar are processed in the microprocessor. Thus, a detection signal is produced when a sonar receives an object echo that lies within its working range. Object echoes that lie outside the defined window are sorted-out by the microprocessor and no detection signal is produced in response to these echoes.

The microprocessor processes the signals delivered by sensing devices which detect the presence of objects, persons, movements and directions within the measuring area. The microprocessor samples signals to a micro¬ program, which processes the signals and delivers signals to a further microprocessor which controls opening and closing of the gates and optionally other functions, such as alarm functions and the like.

The embodiment illustrated in Figure 1 thus includes a sensing device 8 which is mounted in a front gatepost 4, as seen in the direction of the arrow A in Figure l, and which faces in the permitted direction of movement and senses the area externally of the gate. A second sensing device 9 is fitted in a rear gatepost 4 and also faces the permitted direction of movement, but senses the area inwardly of the gate.

The entrance system according to the embodiment illus¬ trated in Figures 1 and 2 operates in the following manner.

When a person moves towards the gate and reaches the predetermined measuring area, there is detected an "in"- signal which activates an "inpassage"-signal. The gate is opened and a timer is started at the same time. The preset timer determines the length of time that the gate shall remain open before returning to its normal, closed position. The rearwardly directed sensing device 9 is blocked during this preset time period.

If the incoming person stops and stands still in the inner measuring area after the preset time has lapsed, the inner sonar will detect the presence of an object in its measuring area, which results in the gate being closed and the system producing a "wrong way" alarm. An external alarm, such as an acoustic alarm signal or a light signal, is also coupled to this function. In this operational state of the system other people are prevented from entering the store in the external measuring area.

The system is such that the sonar which first receives a signal is superordinate to other sonars. In this way, the gate is opened automatically but has the safety function of never closing onto a person, for instance a child, or an object located behind and inwardly of the gate.

Figures 3-5 illustrate a second preferred embodiment of the invention in which the entrance system includes a gated entrance which when in its normal position maintains the entrance opening free for passage of people and/or objects into the store. In this system, the gate is normally open and is closed only when people, or objects, attempt to exit from the store through the "wrong" passageway. In order to achieve this, it is necessary to detect the presence of people and/or objects within a defined area inwardly of the open gate.

According to the invention, the presence of people and/or objects is detected with the aid of a sonar system of the kind described in the aforegoing, which enables the area inwardly of the gate to be sensed effectively and also enables the direction in which objects and/or people move within this area to be detected. As before described, the sonar signals are spread and diverge in the form of lobes, such as to generate a defined sensing area. The extent of this area will depend on the maximum spread of the acoustic signal by the microphone, this spread reaching, for instance, +/- 8° with an attenuation of -3 dB. In this type of entrance system in which the gates are normally open, the area inwardly of the gate to be sensed mostly has a size which requires not only one but several microphones in order to function fully satisfactorily. This solution is both expensive and impractical.

This problem has been solved in accordance with the invention with a sonar unit which includes a system having only one sonar which is mounted on a motor-driven shaft and stepped forwards incrementally. This increases the "viewing angle" of the system and the sonar is able to scan the whole of the contemplated area. This motor- driven sonar control provides the advantage of needing only one sonar to cover the Whole of the scanning area, while achieving a high degree of flexibility with regard to the need to adapt the measuring area to suit different store solutions.

Figure 3 illustrates an inventive sonar unit which can be mounted on a post or a wall. The unit includes a microprocessor 12 which includes drive stages for the sonar motor 14. The motor 14 functions to step forwards a shaft 16 which carries the sonar microphone. The unit also includes a drive stage 26 for the sonar microphone, an amplifier 30 and a mixer 28, which are conveniently mounted on a separate circuit board 20.

The block schematic illustrated in Figure 4 shows how the sonar unit of Figure 3 operates. The microprocessor 22 delivers signals to the drive stage of the sonar motor 24, which steps the motor forwards through one increment. The microprocessor 22 then sends a signal to the drive stage of the microphone 26, which transmits ultrasonic pulses of a duration of about 250 μs and with a high energy content. For instance, the voltage in the pulse or signal may reach 250 V. The signal then passes to the adjustable mixer 28, which is set so that the signal will be transferred to the microphone 18. When the acoustic pulse has left the microphone 18, the mixer 28 is adjusted to receive any echo that may be captured by the microphone 18, in the form of a weak acoustic impact. The received signal is greatly amplified in an amplifier 30 while the identification of the signal is checked by checking that the signal has the same frequency as the transmitted signal. Signals which lie within other frequency bands are sorted-out. The amplifier output signal is delivered to the microprocessor, which receives and registers information that an echo has been detected.

The sonar thus transmits one or more ultrasonic pulses and awaits echoes from objects located within the measuring area. After each measuring occasion, the microphone is rotated by the stepping motor to the next measuring angle and a new sensing or scanning operation is carried out. The software program controls rotation of the microphone by the stepping motor so as to rotate the microphone through, for instance, 15° between each sensing or scanning position. The software program also controls the number of distinct sensing or scanning positions, so that the whole of the measuring area is sensed/scanned by one single sonar unit.

In accordance with a further preferred embodiment of the invention, the flexibility of the system is enhanced by incorporating in the preset measuring area described above, and within which the sonar identifies the echoes, a self-learning function which renders the measuring area adjustable. This is particularly beneficial, since it enables the system to be adapted to restructuring and other modifications to the store/gate system, since such structural changes will normally render the preprogrammed measuring area irrelevant and in need of change.

Thus, in accordance with the invention, the sonar unit has been provided with a self-learning function which enables the system to examine and record the relevant measuring area with the aid of an initiation routine which is carried out in conjunction with installation of the system; see in particular Figure 5. Subsequent to installing the entrance system and the sonar system, the desired measuring area is screened-off with the aid of stationary objects placed in line with the outer limits of said area. After having manually initiated the self- learning function, for instance through a keyboard, (see Figure 5) , the sonar begins to measure the measuring area concerned. The sonar transmits an ultrasonic pulse and awaits, detects and registers the echo that is reflected from an object positioned on the outer limit of said area. The motor moves the sonar to the next measuring point and the detecting and registering procedure is repeated. When the entire measuring area has been measured in this way, the sonar is ready to operate in a normal way.

The sonar microphone restricts the outer measuring area to about 15-20 m. Since it is essential to maintain the sound propagation time at a favourable low level, the maximum measuring range of the sonar is preferably restricted with the aid of the software program to a distance suitable for gate application, for instance a distance of three meters. Thus, in the self- earning procedure the sonar will assume initially that the measuring area is three meters in all measuring directions. If the sonar does not receive any echoes within the three meter distance when following the self- learning procedure described above, all maximum distances are set to three meters. The sonar transmits one or more ultrasonic pulses and awaits echoes from an object within the maximum measuring range. If an echo is detected and if it is established that this echo lies within the predetermined maximum measuring range, the value is stored in the computer memory. The computer memory is preferably of the EEprom type, in which stored data can be written-over an unlimited number of times. This type of memory will also retain data if the supply of electric current to the computer fails.

Figure 5 illustrates a program description in the form of a flowsheet which describes the control of the sonar unit and the gates. One or more preselected programs are chosen when initiating the system, for instance a self- learning program, a maximum measuring range program and/or a program which determines the number of acoustic pulses that are transmitted at each measuring point.

In order for the system to function satisfactorily with the gate system in which the gate is normally open, it is necessary to provide some type of sensing arrangement which will indicate to the system that a person or an object approaches the gate opening from outside the locality. This arrangement may comprise forwardly facing sonars, as in the case of Figures 1 and 2, a single photocell or some other suitable sensing unit.

Figure 6 illustrates a system construction in which a simple photocell is used to sense the area outside the gate opening. The gate motor and therewith the position of the gate are controlled by the sonar unit according to Figures 3 and 4 together with the photocell. The arrangement, or system, also includes limit switches which detect the outer limits of the gate, and an external alarm, such as an acoustic and/or light alarm, connected to the gate unit. A start button for manual adjustment of the opening and closing movements of the gate may be installed, for instance, at a reception desk.

When a person/object is detected approaching the gate opening, a pulse is initiated which starts a timer in the gate control unit. The "wrong way"-signal from the sonar is blocked while the timer is active. This enables people to pass through the area sensed by the sonar and through the entrance system without an alarm being triggered. Should a person remain in the measuring area after the timer has been switched-off, or if some other person has entered the measuring area, the gate is closed and the alarm is triggered, this alarm being a light and/or acoustic alarm. The gate is reopened, after the person has left the measuring area.

If someone should attempt to fool the system, for instance by blocking a photocell on the outside of the gate so as to prevent the gate from being closed, the system will sense that the photocell is blocked after a predetermined time period has lapsed. The gate is then closed and held closed until the photocell is no longer blocked.

When practicing the aforedescribed sensing method, it may be difficult on certain occasions for the system to decide which echo has been detected. This difficulty can result in some uncertainty concerning the detected distance.

This problem has been solved in accordance with a preferred embodiment of the invention by giving an individual identity to each pulse transmitted by the sonar. This is achieved by mixing each individual ultrasonic pulse with a binary code, so that the ultrasonic pulse leaving the microphone will have an overlaid binary information code. This overlaid infor¬ mation and identification code can be achieved with the aid of a frequency modulated ultrasonic carrier wave (FMUB) , an amplitude modulated ultrasonic carrier wave (AMUB) or a pulse width modulated ultrasonic carrier wave (PWMUB) . Thus, when detecting an echo it is possible to identify the transmitted pulse and to read-off the correct distance or the correct direction of movement.

It will be understood that the sensing devices can be mounted in a number of different places in the vicinity of the entrance passageway, such as on wall sections and other proximal units. It is preferred, however, to mount the devices on posts, since this enables the whole of the sensing and control equipment to be incorporated in the post, which simplifies the laying of cables and increases security. A number of supplementary functions can also be included in the inventive system, such as counting the number of people entering through the passageway, etc. The system may also be supplemented with different acoustic and light alarms, for instance with a recorded message which informs a customer that he/she is going the wrong way. The gates may also be provided with panic catches in both directions, which cause the gates to yield and open when subjected to a given pressure.

Claims

1. A gated entrance control system, preferably for retail stores, in which at least one openable and closable gate is mounted in a defined entrance passageway (2) , said system comprising means (10) for controlling opening and closing of the gate (8), and sensor means (8, 9, 18) which functions to sense the presence of an object or persons within a defined measuring area in the vicinity of the entrance passageway (2), c h a r a c t e r i z e d in that the sensing means includes a sonar unit (8, 9) which is mounted in or in the vicinity of the passageway (2) and which includes a transmitter/receiver means for transmitting ultrasonic pulses and receiving reflected ultrasonic pulses, and a microprocessor (12) for controlling the transmitter/receiver means and delivering signals to the control means (10) in response to the reflected ultrasonic pulses.

2. A system according to Claim 1, c h a r a c ¬ t e r i z e d in that the transmitter/receiver means (8, 9, 18) is connected to a motor (14) which steps the transmitter/receiver means to determined positions.

3. A system according to any one of Claims 1-2, c h a r a c t e r i z e d in that the transmitter/re¬ ceiver means (8, 9, 18) is constructed to transmit and receive a plurality of mutually sequential ultrasonic pulses in each position of said means, said pulses preferably being between 2 and 5 in number.

4. A system according to any one of Claims 2-3, c h a r a c t e r i z e d in that the motor is con¬ structed to rotate the transmitter/receiver means (8, 9, 18) through about 15° with each step.

5. A system according to any one of Claims 1-4, c h a r a c t e r i z e d in that the transmitter/re¬ ceiver means (8, 9, 18) is constructed to transmit the ultrasonic pulses in a generally horizontal direction towards the defined measuring area, behind or in front of the gate passageway.

6. A system according to any one of Claims 1-5, c h a r a c t e r i z e d by means for giving the transmitted ultrasonic pulse an individual identity which is detected upon receipt before the reflected ultrasonic pulse is accepted for registration.

7. A system according to Claim 6, c h a r a c - t e r i z e d by means for mixing th .ultrasonic pulse with a binary code so that each ultrasonic pulse will have an overlaid binary information code and therewith an individual identification.

8. A system according to any one of Claims 1-7, c h a r a c t e r i z e d in that the microprocessor is constructed to control the measuring area within which the sensing means detects reflected signals and includes a self-learning function which enables the predetermined measuring area to be changed.

9. A method of controlling the customer stream in a defined entrance passageway to a store locality with the aid of openable and closable entrance gates, c h a r a c t e r i z e d by transmitting at least one ultrasonic pulse from a transmitter to a defined measuring area; receiving a reflected ultrasonic pulse in a receiver; identifying and checking reflected ultrasonic pulses; registering accepted ultrasonic pulses in a microprocessor; delivering signals from the microprocessor to a gate motor for opening and closing the gate in accordance with the content of the signals.

10. A method according to Claim 9, c h a r a c ¬ t e r i z e d by delivering signals from the micro¬ processor to a stepping motor (14) for stepping a transmitter/receiver means (8, 9, 18), said means > transmitting and awaiting the possible receipt of at least one ultrasonic pulse in each stepped position.