A system for separating people and identifying directions based on a light curtain

Abstract

The present invention relates to the field of warehouse automation technology, and in particular, provides a system for separating people and identifying their direction based on light curtains. In this system, a light curtain unit is used to emit and receive infrared light beams and detect light beam obstruction. The light curtain unit collects real-time information about the obstruction of the light beam emitted by the light curtain transmitter by a moving target and transmits the obstruction information to a control unit. The control unit processes the data collected by the light curtain unit, analyzes the obstruction length, motion characteristics, obstruction characteristics, and light intensity attenuation curve of the light beam, identifies people and objects, and determines their direction of movement. The output unit transmits the recognition result of the control unit to an external execution unit to trigger the corresponding control logic. The alarm reset unit is used to detect an alarm and automatically resets itself after the alarm event is resolved, sending objects that are stuck in the protection area out of the protection area. The system efficiently and accurately identifies people and objects, and can determine their direction of movement, thus avoiding system paralysis.

Description

Technical Field

[0001] The present invention relates to the technical field of warehouse automation, and in particular to a system for separating people and identifying directions based on a light curtain. Background Art

[0002] The widespread use of automated equipment in modern warehousing and logistics has greatly improved operational efficiency. However, warehousing environments often involve a mixed flow of people and goods. Accurately distinguishing between people and objects to ensure both safety and operational efficiency is a pressing issue.

[0003] Light curtains, as infrared beam-based detection devices, offer advantages such as fast response, high accuracy, and strong anti-interference capabilities, effectively addressing these issues. However, existing light curtain technology, primarily used for security and object detection, suffers from several drawbacks: Traditional light curtains can only detect obstructions and are unable to distinguish between humans and cargo (such as pallets); they rely on fixed thresholds to determine direction of movement and are unable to adapt to complex motion patterns (such as turning in place); and they lack a self-recovery mechanism, rendering the system inoperable if obstructed by foreign objects or if the light source fails. Summary of the invention

[0004] In view of this, the present invention provides a system for separating people and identifying directions based on light curtains, which is used to efficiently and accurately identify people and objects, and can determine their movement directions to avoid system paralysis.

[0005] In a first aspect, the present invention provides a system for separating people and identifying directions based on a light curtain, characterized in that the system comprises: a light curtain unit, a control unit, an output unit, an external execution unit, and an alarm reset unit;

[0006] The light curtain unit includes a light curtain transmitter and a light curtain receiver relatively arranged in the storage channel, which are used to emit and receive infrared light beams and detect the obstruction of the light beams; the light curtain unit collects the obstruction information of the light beam emitted by the moving target from the light curtain transmitter in real time, and transmits the obstruction information to the control unit, wherein the obstruction information includes the obstruction length, obstruction position and obstruction time, and the obstruction light intensity attenuation; the control unit is used to process the data collected by the light curtain unit, analyze the obstruction length, motion characteristics, obstruction characteristics and light intensity attenuation curve of the light beam, identify human bodies and objects, and determine their movement direction; the output unit is used to transmit the recognition result of the control unit to the external execution unit to trigger the corresponding control logic; the alarm reset unit is used to detect the alarm, and automatically reset after the alarm event is lifted, and send objects that are stationary in the protection area out of the protection area.

[0007] Optionally, the scanning plane of the light curtain unit faces the area at a height of 30-50 cm from the ground of the storage channel; upon initialization, the length, movement speed and movement direction of the moving target are pre-set in the light curtain unit as legal trigger event features for allowing passage.

[0008] Optionally, the control unit analyzes the occlusion length, motion characteristics, occlusion characteristics and light intensity attenuation curve of the light beam through a preset algorithm to determine whether the type of the moving target is a human body or an object; the light intensity attenuation curve is fitted by the least squares method to extract key parameters, including: initial light intensity I0, used to reflect the surface reflectivity of the object, the initial light intensity of the metal tray is 100-200μW, and the initial light intensity of the human body is 10-30μW, that is, the initial light intensity of the metal tray is greater than the initial light intensity of the human body; the surface attenuation coefficient α, used to characterize the absorption characteristics of the material, the attenuation coefficient of human skin is 0.02-0.05, and the initial light intensity of the plastic box is 0.01-0.06. The attenuation coefficient is 0.03-0.07, that is, the attenuation coefficient of human skin is greater than that of the plastic box; the human cadence is 0.8-1.4Hz, and the interval time distribution of the corresponding light intensity occlusion event is 1.2-2.5s Poisson distribution. The mechanical movement of an object is usually uniform linear motion, that is, a fixed occlusion interval. If the occlusion length changes intermittently, the occlusion time interval obeys the 1.2-2.5s Poisson distribution, and the occlusion light intensity decays exponentially, then the moving target is a human body; if the occlusion length remains unchanged or changes continuously, the occlusion time interval is a fixed interval, and the occlusion light intensity decays linearly, then the moving target is an object.

[0009] Optionally, the control unit determines the movement direction of the moving target through a preset algorithm based on the light beam blocking sequence and blocking time; the movement direction is determined by the following rules: if the light beam blocking sequence conforms to the preset movement direction, it is determined to be the forward direction; if the light beam blocking sequence does not conform to the preset movement direction, it is determined to be the backward direction.

[0010] Optionally, the output unit transmits the recognition result of the control unit to the external execution unit, triggering the corresponding control logic, where the recognition result includes the type of moving target and the direction of the moving target; when the external execution unit triggers the control logic to enter the alarm state, after the alarm event is lifted, the alarm reset unit is immediately started until the object stagnant in the protection area leaves the protection area.

[0011] Alternatively, when a person walks, the alternating movement of the legs causes the beam blocking interval time t to obey the Poisson distribution with parameter λ, which is expressed as:

[0012] ;

[0013] in , T is the average step frequency, which is 1.2-2.5s.

[0014] Optionally, the light intensity attenuation curve is defined as a function of the time variation of the light intensity after the light beam is reflected from the object surface and propagated to the light curtain receiver after time t, and its expression is:

[0015] ;

[0016] Where I0 is the initial light intensity; R(θ) is the reflectivity of the object surface, which is related to the incident angle θ; α is the attenuation coefficient of the surface, which is related to the dielectric constant of the material; is the ambient light noise.

[0017] In the technical solution provided by the present invention, the system includes a light curtain unit, a control unit, an output unit, an external execution unit and an alarm reset unit; the light curtain unit includes a light curtain transmitter and a light curtain receiver relatively arranged in the storage channel, which are used to emit and receive infrared light beams and detect the obstruction of the light beams; the light curtain unit collects the obstruction information of the light beam emitted by the moving target from the light curtain transmitter in real time, and transmits the obstruction information to the control unit, wherein the obstruction information includes the obstruction length, obstruction position and obstruction time, and the obstruction light intensity attenuation; the control unit is used to process the data collected by the light curtain unit, analyze the obstruction length, motion characteristics, obstruction characteristics and light intensity attenuation curve of the light beam, identify human bodies and objects, and determine their movement direction; the output unit is used to transmit the recognition result of the control unit to the external execution unit to trigger the corresponding control logic; the alarm reset unit is used to detect the alarm, and automatically reset after the alarm event is lifted, and send the objects stagnant in the protection area out of the protection area. The system efficiently and accurately identifies human bodies and objects, and can determine their movement direction, avoiding system paralysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic diagram of a system for separating people and identifying their directions based on a light curtain, provided in an embodiment of the present invention;

[0020] Figure 2 A cargo movement diagram provided by an embodiment of the present invention;

[0021] Figure 3 Human body motion diagram provided by the embodiment of the present invention

[0022] Figure 4 A comparison diagram of light intensity attenuation curves provided in an embodiment of the present invention.

[0023] Reference numerals: 1 - light curtain unit; 2 - goods; 3 - human body; 4 - metal attenuation curve; 5 - plastic box attenuation curve; curve 6 - human body attenuation curve. Detailed implementation manners

[0024] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] It should be clear that the described embodiments are only some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "the" and "said" used in the embodiments of the present invention are also intended to include the plural forms unless the context clearly indicates otherwise.

[0027] It should be understood that the term " / and / " used herein is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0028] Depending on the context, the word "if" as used herein may be interpreted as "when" or "while" or "in response to determining" or "in response to detecting". Similarly, depending on the context, the phrase "if determined" or "if detecting (stated condition or event)" may be interpreted as "when determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)".

[0029] Figure 1 Schematic diagram of the system for separating people and identifying directions based on a light curtain provided for the embodiments of the present invention, as Figure 1 shown, the system includes: a light curtain unit, a control unit, an output unit, an external execution unit, and an alarm reset unit;

[0030] The light curtain unit includes a light curtain transmitter and a light curtain receiver relatively arranged in the storage channel, which are used to emit and receive infrared light beams and detect the obstruction of the light beams; the light curtain unit collects the obstruction information of the light beam emitted by the light curtain transmitter in real time, and transmits the obstruction information to the control unit, wherein the obstruction information includes the obstruction length, obstruction position and obstruction time, and the obstruction light intensity attenuation; the control unit is used to process the data collected by the light curtain unit, analyze the obstruction length, motion characteristics, obstruction characteristics and light intensity attenuation curve of the light beam, identify human bodies and objects, and determine their movement direction; the output unit is used to transmit the recognition result of the control unit to the external execution unit to trigger the corresponding control logic. For example, when a human body is detected entering the dangerous area, the output unit triggers the equipment to stop running; when an object is detected passing, the output unit triggers the sorting system to sort; the alarm reset unit is used to detect an alarm, and automatically reset after the alarm event is lifted, and send objects that are stationary in the protection area out of the protection area, wherein the control logic includes but is not limited to alarm and equipment stop.

[0031] In an embodiment of the present invention, the scanning plane of the light curtain unit faces the area at a height of 30-50 cm from the floor of the storage channel; upon initialization, the length, speed and direction of the moving target are pre-set in the light curtain unit as legal trigger event features for allowing passage.

[0032] In the embodiment of the present invention, the control unit analyzes the occlusion length, motion characteristics, occlusion characteristics and light intensity attenuation curve of the light beam through a preset algorithm to determine the type of the moving target is a human body or an object; the light intensity attenuation curve is fitted by the least squares method to extract key parameters, including: initial light intensity I0, which is used to reflect the surface reflectivity of the object. The initial light intensity of the metal tray is 100-200μW, and the initial light intensity of the human body is 10-30μW, that is, the initial light intensity of the metal tray is greater than the initial light intensity of the human body; the surface attenuation coefficient α, which is used to characterize the absorption characteristics of the material. The attenuation coefficient of human skin is 0.02-0.05, and the attenuation coefficient of plastic is 0.01-0.06. The attenuation coefficient of the box is 0.03-0.07, that is, the attenuation coefficient of human skin is greater than that of the plastic box; the human cadence is 0.8-1.4Hz, and the interval time distribution of the corresponding light intensity occlusion event is 1.2-2.5s Poisson distribution. The mechanical movement of an object is usually uniform linear motion, that is, a fixed occlusion interval. If the occlusion length changes intermittently, the occlusion time interval obeys the 1.2-2.5s Poisson distribution, and the occlusion light intensity decays exponentially, then the moving target is a human body; if the occlusion length remains unchanged or changes continuously, the occlusion time interval is a fixed interval, and the occlusion light intensity decays linearly, then the moving target is an object.

[0033] In the embodiment of the present invention, Figure 2 As shown, the arrow points to the direction of light from the light curtain transmitter to the light curtain receiver. When the moving target is regular goods, the blocking length and blocking interval are fixed;Figure 3 As shown in the figure, the arrow points to the direction of light from the light curtain transmitter to the light curtain receiver. When the moving target is a human body, the interval is Poisson distributed in the range of 1.2-2.5s due to the occlusion of the human leg step frequency.

[0034] In an embodiment of the present invention, the control unit determines the movement direction of the mobile target through a preset algorithm based on the blocking order and blocking time of the light beams; the movement direction is determined by the following rules: if the blocking order of the light beams conforms to the preset movement direction, it is determined to be a forward direction; if the blocking order of the light beams does not conform to the preset movement direction, it is determined to be a backward direction.

[0035] In an embodiment of the present invention, the output unit transmits the recognition result of the control unit to the external execution unit, triggering the corresponding control logic, wherein the recognition result includes the type of the moving target and the direction of the moving target; when the external execution unit triggers the control logic to enter the alarm state, after the alarm event is lifted, the alarm reset unit is immediately started until the object stagnant in the protection area leaves the protection area.

[0036] In the embodiment of the present invention, the interval time t of light beam obstruction caused by alternating movements of the legs when a person walks obeys a Poisson distribution with a parameter λ, and its expression is:

[0037] ;

[0038] in , T is the average step frequency, which is 1.2-2.5s.

[0039] In the embodiment of the present invention, the light intensity attenuation curve is defined as a function of the time-varying light intensity after the light beam is reflected from the object surface and propagated to the light curtain receiver after a time t. The expression is:

[0040] ;

[0041] Where I0 is the initial light intensity; R(θ) is the reflectivity of the object surface, which is related to the incident angle θ; α is the attenuation coefficient of the surface, which is related to the dielectric constant of the material; is the ambient light noise.

[0042] In the embodiment of the present invention, Figure 4 As shown, curve 4 is the metal attenuation curve; curve 5 is the plastic box attenuation curve; curve 6 is the human body attenuation curve; the metal light intensity attenuation curve (curve 4): τ≈1.1ms, I0≈120μW, the waveform is smooth and linear attenuation; the plastic box light intensity attenuation curve (curve 5): τ≈800μs, I0≈55μW, showing medium and slow attenuation; the human body light intensity attenuation curve (curve 6): τ≈380μs, I0≈15μW, showing exponential attenuation accompanied by high-frequency vibration noise.

[0043] In an embodiment of the present invention, the scenario is described as follows: In a storage channel, personnel and heavy goods flow together, and it is necessary to accurately distinguish between personnel and goods, and determine their direction of movement to ensure personnel safety and work efficiency; at the same time, after the alarm is triggered and the alarm event is lifted, the heavy goods stagnant in the protection area must be transported away by a conveyor belt.

[0044] Implementation steps: The light curtain unit collects real-time information about beam obstructions. The control unit analyzes the beam obstruction length and characteristics, as well as the light intensity attenuation curve, to determine the type of moving target. The control unit determines the target's direction of movement based on the order and duration of beam obstructions. If the moving target is a person, the output unit triggers an alarm. Once the alarm is resolved, the alarm resets until the remaining cargo is transported out of the protected area. If the moving target is an object, the output unit triggers the sorting system for sorting.

[0045] The characteristics of the system in the present invention are: direction recognition, by analyzing the blocking sequence and blocking time of the light beam, the movement direction of the moving target can be accurately determined; fast response: the response speed of the light curtain unit is extremely fast, and the recognition can be completed within milliseconds; strong anti-interference ability: the light curtain unit is not affected by ambient light and background interference, and is suitable for complex environments. Low cost: the light curtain unit has a low cost and is suitable for large-scale applications. The system in the present invention can efficiently and accurately identify human bodies and objects, and determine their movement direction, and has an alarm reset function, which automatically resets when the system fails. It has the advantages of high precision, fast response, strong anti-interference ability, low cost, etc. It is suitable for storage channels, as well as for scenes such as automated sorting systems and safety protection areas, and has broad application prospects.

[0046] In the technical solution provided by the present invention, the system includes a light curtain unit, a control unit, an output unit, an external execution unit and an alarm reset unit; the light curtain unit includes a light curtain transmitter and a light curtain receiver relatively arranged in the storage channel, which are used to emit and receive infrared light beams and detect the obstruction of the light beams; the light curtain unit collects the obstruction information of the light beam emitted by the moving target from the light curtain transmitter in real time, and transmits the obstruction information to the control unit, wherein the obstruction information includes the obstruction length, obstruction position and obstruction time, and the obstruction light intensity attenuation; the control unit is used to process the data collected by the light curtain unit, analyze the obstruction length, motion characteristics, obstruction characteristics and light intensity attenuation curve of the light beam, identify human bodies and objects, and determine their movement direction; the output unit is used to transmit the recognition result of the control unit to the external execution unit to trigger the corresponding control logic; the alarm reset unit is used to detect the alarm, and automatically reset after the alarm event is lifted, and send the objects stagnant in the protection area out of the protection area. The system efficiently and accurately identifies human bodies and objects, and can determine their movement direction, avoiding system paralysis.

[0047] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments, and will not be described herein again.

[0048] The foregoing is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A system for separating people and identifying directions based on a light curtain, characterized in that, The system includes: a light curtain unit, a control unit, an output unit, an external execution unit and an alarm reset unit; The light curtain unit includes a light curtain transmitter and a light curtain receiver which are arranged relative to each other in the storage channel, and are used to emit and receive infrared light beams and detect the obstruction of the light beams; the light curtain unit collects the obstruction information of the light beam emitted by the light curtain transmitter by the moving target in real time, and transmits the obstruction information to the control unit, wherein the obstruction information includes the obstruction length, obstruction position and obstruction time, and the obstruction light intensity attenuation; the control unit is used to process the data collected by the light curtain unit, analyze the obstruction length, motion characteristics, obstruction characteristics and light intensity attenuation curve of the light beam, identify human bodies and objects, and determine their movement direction; the output unit is used to transmit the recognition result of the control unit to the external execution unit to trigger the corresponding control logic; the alarm reset unit is used to detect the alarm, and automatically reset after the alarm event is lifted, and send the objects stagnant in the protection area out of the protection area; The control unit analyzes the occlusion length, motion characteristics, occlusion characteristics and light intensity attenuation curve of the light beam through a preset algorithm to determine the type of the moving target is a human body or an object; the light intensity attenuation curve is fitted by the least squares method to extract key parameters, including: initial light intensity I0, used to reflect the surface reflectivity of the object. The initial light intensity of the metal tray is 100-200μW, and the initial light intensity of the human body is 10-30μW, that is, the initial light intensity of the metal tray is greater than the initial light intensity of the human body; the surface attenuation coefficient α, used to characterize the absorption characteristics of the material. The attenuation coefficient of human skin is 0.02-0.05, and the attenuation coefficient of the plastic box is 0. The coefficient is 0.03-0.07, that is, the attenuation coefficient of human skin is greater than that of the plastic box; the human cadence is 0.8-1.4Hz, and the interval time distribution of the corresponding light intensity occlusion event is 1.2-2.5s Poisson distribution. The mechanical movement of an object is usually uniform linear motion, that is, a fixed occlusion interval. If the occlusion length changes intermittently, the occlusion time interval obeys the 1.2-2.5s Poisson distribution, and the occlusion light intensity decays exponentially, then the moving target is a human body; if the occlusion length remains unchanged or changes continuously, the occlusion time interval is a fixed interval, and the occlusion light intensity decays linearly, then the moving target is an object.

2. The system according to claim 1, wherein The scanning plane of the light curtain unit faces the area 30-50 cm above the ground of the storage channel; initialization, the length, movement speed and movement direction of the moving target are pre-set in the light curtain unit as legal trigger event features for allowing passage.

3. The system according to claim 1, wherein The control unit determines the movement direction of the mobile target through a preset algorithm based on the light beam blocking sequence and blocking time; the movement direction is determined by the following rules: if the light beam blocking sequence conforms to the preset movement direction, it is determined to be the forward direction; if the light beam blocking sequence does not conform to the preset movement direction, it is determined to be the backward direction.

4. The system according to claim 1, wherein The output unit transmits the recognition result of the control unit to the external execution unit, triggering the corresponding control logic, where the recognition result includes the type of moving target and the direction of the moving target; when the external execution unit triggers the control logic to enter the alarm state, after the alarm event is lifted, the alarm reset unit is immediately started until the object that is stationary in the protection area leaves the protection area.

5. The system according to claim 1, characterized in that The interval time t of beam blocking caused by alternating legs movement when a person walks follows a Poisson distribution with parameter λ, and its expression is: ； Among them , T is the average step frequency, taking 1.2 - 2.5 s.

6. The system according to claim 1, characterized in that, The light intensity attenuation curve is defined as the function of the light intensity that changes with time after the light beam is reflected from the object surface and propagates to the light curtain receiver after time t. Its expression is: ； Among them, I0 is the initial light intensity; R(θ) is the reflectivity of the object surface, which is related to the incident angle θ; α is the attenuation coefficient of the surface, which is related to the dielectric constant of the material; is the ambient light noise.

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