JP7531998B2 - Person recognition device for garbage collection vehicles - Google Patents

Description

The present invention relates to a person recognition device that uses image processing technology to recognize workers and others near a refuse input port located at the rear of a refuse collection vehicle, and in particular to the layout of the camera.

Conventionally, refuse collection vehicles are equipped with a refuse loading device in a refuse input box installed at the rear of the vehicle chassis, and refuse input from a refuse input opening is scraped into the refuse input box by a rotating plate or a loading plate, and loaded into a refuse storage box. In addition, various monitoring systems have been proposed to monitor people near the refuse input opening in order to prevent workers who input refuse into the refuse input opening from inadvertently getting caught up in the garbage loading device.

For example, in the monitoring system described in Patent Document 1, a camera is disposed at the upper rear of the garbage dump box as an imaging means, and is adapted to capture images of the garbage dump opening below and a specified area behind it. If it is determined in an image captured by the camera while the garbage loading device is in operation that a person has entered a preset no-entry area, the operation of the garbage loading device is stopped.

Patent No. 4283568

However, in the conventional surveillance system described above, the camera is positioned at an angle backward, and the optical axis of the imaging lens is angled significantly backward from the vertical downward direction. This means that in the captured image, part of the distance (front-to-back distance) between the garbage inlet and the person behind it appears in the depth direction of the screen, making it difficult to tell whether the person is very close to the garbage inlet or far away.

In other words, as shown in an example in Figure 9, when the optical axis A of the imaging lens of the camera C is angled far backward and the inclination angle θ from the vertical downward becomes large, even if the head of person H is about to enter the dangerous area (shown by hatching) above the garbage inlet, on the image plane it appears that there is a large gap D between the rear edge of the garbage inlet, i.e., the boundary line B between the dangerous area and the safe area, and the person's head.

In this way, in conventional surveillance systems, when a person crosses the boundary line and enters a dangerous area, the determination is delayed, and there is a risk that the operation of the garbage loading device will not be stopped in time. On the other hand, if the criteria for determination are changed to prevent this, it may be erroneously determined that a person has entered a dangerous area when in fact they have not, leading to frequent unnecessary operation shutdowns and a loss of convenience.

With this in mind, the objective of the present invention is to devise a camera layout that will enable more accurate determination from captured images of whether or not a person is near the trash dump (the dangerous area).

The person recognition device of the present invention is mounted on a garbage collection vehicle having a garbage dump box at the rear of the vehicle chassis and a garbage loading device provided within the garbage dump box and capable of loading garbage into the garbage storage box, and is a person recognition device that recognizes people near a garbage dump opening that opens along the back surface of the garbage dump box from its front edge to its rear edge, the person recognition device comprising: a camera disposed outside the garbage dump box and above the garbage dump opening; an image processing device that inputs image data captured by the camera to include the rear edge and determines whether or not a person is present in a dangerous area set on the front side of the vehicle with the rear edge of the garbage dump opening, which is located forward of the rear end of the vehicle in the image, as a boundary; and a detection device that detects whether or not a person is present in the dangerous area by the image processing device. and an emergency stop device which stops the operation of the garbage loading device when it is determined that a person is present, the camera is attached to a stay on an upper part of the garbage dump box so that an imaging lens is located halfway between the front edge and the rear edge in a plan view and so that the direction of the optical axis of the imaging lens is adjustable, and is configured to determine that a loading member of the garbage loading device is operating in a dangerous range in which there is a risk of entanglement of part of a person's body inside the garbage dump box, and the emergency stop device is configured to stop the operation of the garbage loading device when it is determined by the image processing device that a person is present in the dangerous area and that the loading member is operating in the dangerous range.

In a person recognition device configured in this way, the camera is disposed above the garbage inlet, so the direction of the optical axis of the imaging lens pointing from here to the garbage inlet below is closer to a vertically downward direction than in the conventional example (Patent Document 1). This makes the depth direction of the captured image closer to the vertical direction, and the front-to-rear distance between the garbage inlet and the person behind it in this image is mainly shown on the image plane.

As a result, the image processing device can determine, based on the image data, more accurately than ever before whether a person approaching the garbage inlet from behind has entered a dangerous area. Therefore, by stopping the operation of the garbage loading device based on the result of this determination, it is possible to reduce the frequency of unnecessary operation stoppages while suppressing delays in operation stoppages, thereby ensuring sufficient safety.

In addition, for example, a loading member such as a rotating plate of a rotary garbage loading device rotates inside the garbage dump box on the side opposite the garbage dump opening (the side closer to the garbage storage box) and even if there is no danger to a person near the garbage dump opening, the operation of the garbage loading device will not be stopped in an emergency based on the results of the determination by the image processing device. In other words, the frequency of unnecessary operational shutdowns of the garbage loading device can be further reduced, improving convenience.

With the person recognition device for a garbage collection vehicle according to the present invention, the distance between the garbage inlet and the person behind it appears mainly on the image plane in the captured image, making it possible to determine the position of the person through image processing more accurately than before. Furthermore, even if a person is near the garbage inlet and there is no danger, the operation of the garbage loading device will not be stopped in an emergency based on the results of the determination made by the image processing device. This makes it possible to ensure sufficient safety while minimizing the decrease in convenience due to unnecessary operation stoppages.

1 is a side view showing a refuse collection vehicle according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of a garbage loading device installed in the garbage collection vehicle of FIG. 1. FIG. 2 is a hydraulic circuit diagram of the refuse loading device of the refuse collection vehicle of FIG. 1 . FIG. 2 is a schematic diagram showing a control device for the refuse collection vehicle of FIG. 1 and its input/output state. FIG. 2 is an explanatory diagram showing a schematic configuration of a person recognition device mounted on the sewage collection vehicle of FIG. 1 . 4 is a flowchart illustrating an example of an image processing routine. FIG. 2 is an explanatory diagram showing an example of an image captured by a camera. 5 and shows another embodiment having a different camera layout. FIG. FIG. 6 is a diagram equivalent to FIG. 5 and showing the layout of cameras in a conventional person recognition device.

Below, an embodiment in which the present invention is applied to a rotary type refuse collection vehicle will be described with reference to the drawings. Note that in the following description, for convenience, the front, rear, left and right of the refuse collection vehicle will sometimes be simply referred to as front, rear, left and right.

Figure 1 shows a refuse collection vehicle 100 equipped with a person recognition device according to an embodiment of the present invention, with a refuse collection box 2 and a refuse drop box 3 mounted on the chassis 1, with the rear opening of the refuse collection box 2 communicating with the front opening of the refuse drop box 3. The refuse drop box 3 is supported by a left-right pivot 3a mounted on its top, and is tilted by a pair of left and right tilting cylinders (not shown).

A rectangular trash inlet 4 (see also FIG. 7) for inserting trash is opened at the bottom of the back of the trash bin 3, and is opened and closed by a tailgate 5 that can be raised and lowered. A switch box 6 for operating the trash loading device is provided on the left side of the trash inlet 4, and a camera 7 is disposed above the trash inlet 4 to take pictures of the area around the trash inlet 4, as will be described in more detail below.

As shown enlarged in Figure 2, the inside of the garbage dump box 3 is equipped with a garbage loading device that loads the garbage dumped into the garbage storage box 2. The garbage loading device of this embodiment is a so-called rotary type that scoops up garbage by rotating a rotating plate 10 (loading member) and pushes it into the garbage storage box 2 by a pushing plate 20. That is, first, a rotating shaft 11 is installed at the bottom inside the garbage dump box 3 so as to extend in the width direction, and the base end side of the rotating plate 10 is fixed to this.

In the illustrated example, a hydraulic motor 13 capable of rotating forward and reverse is connected to the end of the rotating shaft 11 via a reduction mechanism 12. Thus, the rotation of the hydraulic motor 13 is torqued up by the reduction mechanism 12 and transmitted to the rotating shaft 11, and the rotating plate 10 rotates integrally with the rotating shaft 11, causing its tip to move back and forth along the bottom wall of the trash bin 3, which has a cross section formed in a roughly semicircular arc shape.

The pusher plate 20 is provided above the rotating plate 10 across the entire width of the trash bin 3, and is supported so that it can swing back and forth around a left-right swing shaft 21 provided at the top of the plate. The pusher plate 20 also has an extension 22 that extends above the swing shaft 21, and a pusher cylinder 24 is installed between the extension 22 and a support pin 23 in front of it, and the extension and contraction of the cylinder causes the pusher plate 20 to swing back and forth.

That is, as shown by the solid line in Figure 2, when the pusher plate 20 is at its most swung position toward the trash storage box 2 (advance limit position), the rotating plate 10 rotates upward without interfering with the pusher plate 20, and the pusher plate 20 subsequently swings toward the trash inlet 4. Then, even after the pusher plate 20 swings to its most swung position toward the trash inlet 4 and reaches the retreat limit position shown by the phantom line in Figure 2, the rotating plate 10 continues to rotate.

The rotating plate 10 thus rotates, sweeping the trash into the trash storage box 2 and stopping once at the set stop position extending forward toward the trash storage box 2 as shown by the solid line in FIG. 2. Then, the pusher plate 20 swings toward the trash storage box 2, pushing the trash on the rotating plate 10 into the trash storage box 2. Then, when the pusher plate 20 reaches the forward limit position again, the rotating plate 10 begins to rotate upward again.

By repeating the rotation of the rotating plate 10 and the swinging of the pushing plate 20 in sync with each other in this way, the garbage thrown into the garbage dump box 3 is continuously loaded into the garbage storage box 2 (hereinafter referred to as garbage loading operation). The configuration of the hydraulic circuit and electronic control device (control system) for operating the rotating plate 10 and the pushing plate 20 in this manner will be described below, but for this purpose, switches LS1 to LS5 for detecting the positions of the rotating plate 10 and the pushing plate 20 are provided inside the garbage dump box 3.

That is, as shown in FIG. 2, there are provided switches LS1 and LS2 that are turned on when the pushing plate 20 is at the forward limit position or the backward limit position, respectively, switch LS3 that is turned on when the rotating plate 10 is at the set stop position, switch LS4 that is turned on when the rotating plate 10 rotates a predetermined angle in the positive direction (clockwise in FIG. 1) from the set stop position, and switch LS5 that is turned on when it has rotated a further predetermined angle.

Switches LS1 and LS2 are adapted to detect a dog (not shown) provided at the end of the oscillating shaft 21 of the pushing plate 20, and switches LS3 to LS5 are adapted to detect a dog (not shown) provided at the end of the rotating shaft 11 of the rotating plate 10. These switches LS1 to LS5 can be, for example, photoelectric switches or proximity switches.

As shown by hatching in Figure 2, the switches LS4 and LS5 detect the angle range Z in which the rotating plate 10 moves from directly below the front edge 4a of the garbage inlet 4 to the rear of the garbage inlet 4 as it rotates and descends until it comes closest to the rear edge 4b of the garbage inlet 4. In this angle range Z, there is a risk that the rotating plate 10 may catch part of the worker's body, so hereinafter this will be referred to as the dangerous angle range Z.

Furthermore, as shown in Figures 1 and 2, emergency stop buttons 60, 61 and an emergency stop plate 62 for stopping the operation of the garbage loading device are disposed near the garbage inlet 4. As shown in Figure 1, the emergency stop button 60 is disposed in the switch box 6 on the left side of the garbage inlet 4, and as shown by the dashed line in Figure 2, the emergency stop button 61 is disposed on the right side of the garbage inlet 4. The emergency stop plate 62 is disposed below the garbage inlet 4 so as to turn the switch SW3 on and off.

- Control system for refuse loading device -
Next, a control system for operating the garbage loading device as described above will be described with reference to Figures 3 and 4. This control system includes a hydraulic circuit for controlling the hydraulic pressure supplied to the hydraulic motor 13 and the pushing cylinder 24 of the garbage loading device, and a control device PLC (Programmable Logic Controller) for outputting control signals to the solenoid control valves V1 and V2 provided in the hydraulic circuit.

First, the hydraulic circuit will be described with reference to Figure 3. This hydraulic circuit includes a hydraulic pump P, an oil reservoir T, an electromagnetic control valve V1 for controlling the pushing cylinder 24, and an electromagnetic control valve V2 for controlling the hydraulic motor 13. Although not shown, the driving force of the engine is transmitted to the hydraulic pump P via a PTO (power take-off).

As an example, the solenoid control valves V1 and V2 are both 6-port, 3-position electromagnetic directional control valves. When the solenoid SOLa is excited, the solenoid control valve V1 switches to the first communication position (upper position in the figure) and supplies hydraulic oil from the hydraulic pump P to the rod-side oil chambers of the pair of pushing cylinders 24, while when the solenoid SOLb is excited, the solenoid control valve V1 switches to the second communication position (lower position in the figure) and supplies hydraulic oil to the head-side oil chambers.

When hydraulic oil is supplied from the solenoid control valve V1 to the head side oil chamber, the pair of pushing cylinders 24 expand to swing the pushing plate 20 forward. On the other hand, when hydraulic oil is supplied to the rod side oil chamber, the pair of pushing cylinders 24 contract to swing the pushing plate 20 backward. Also, when neither solenoid SOLa, SOLb is excited, the solenoid control valve V1 returns to the neutral position (the center position in the figure).

On the other hand, when solenoid SOLc is excited, solenoid control valve V2 switches to the first communication position (lower position in the figure) and supplies hydraulic oil to the forward oil chamber of hydraulic motor 13, causing hydraulic motor 13 to operate in the forward direction. On the other hand, when solenoid SOLd is excited, solenoid control valve V2 switches to the second communication position (upper position in the figure) and supplies hydraulic oil to the reverse oil chamber of hydraulic motor 13, causing hydraulic motor 13 to operate in the reverse direction.

When neither solenoid SOLc nor SOLd is energized, the solenoid control valve V2 returns to its neutral position (the center position in the figure). When both solenoid control valves V1 and V2 are in their neutral positions, the hydraulic oil flows back to the oil reservoir T. In the illustrated hydraulic circuit, V3 is a check valve, and V4 is a relief valve for setting the upper limit of the discharge pressure of the hydraulic pump P.

Next, the input and output states of signals in the control device PLC will be described with reference to FIG. 4. First, power is supplied to the control device PLC by the battery BT shown in the upper left of the figure. Between this battery BT and the ground line K1 on the right side of the figure, a current carrying line K2 is connected so as to extend left and right across the top of the figure, and the key switch SWK of the garbage collection vehicle 100, the PTO switch SWP, the relay coil CR1, etc. are interposed here.

The upstream end of the current carrying line K3 is connected so as to branch off from the current carrying line K2 midway between the key switch SWK and the battery BT, and power is supplied to a signal power supply unit (not shown) of the control device PLC via this current carrying line K3. That is, the contact cr1 of the relay coil CR1 is provided on the upstream side of the current carrying line K3 (the side closer to the battery BT), and when the relay coil CR1 is turned on, the contact cr1 is closed, causing electricity to flow through the current carrying line K3.

This current carrying line K3 is always energized when the garbage loading device is in garbage loading operation, and is provided with switches SW1 to SW3 that are opened and closed in response to the operation of the emergency stop buttons 60, 61 and the emergency stop plate 62 described above with reference to FIG. 2. When the current is cut off by these switches SW1 to SW3, the operation of the control device PLC is stopped, thereby stopping the operation of the garbage loading device. An image processing unit 8 is also provided in the current carrying line K3, which will be described in more detail later.

Furthermore, as shown on the left side of Figure 4, the upstream ends of multiple branch lines are connected to branch off from the current carrying line K3 downstream of the contact cr1 (farther from the battery BT), and each of these branch lines is provided with the switches LS1 to LS5 described above with reference to Figure 2. Based on the signals from these switches LS1 to LS5, the positions of the rotating plate 10 and the pushing plate 20 of the garbage loading device, i.e., the operating status, are detected.

In addition to the above-mentioned switches LS1 to LS5, the input side of the control device PLC is also connected to a start and stop switch for the garbage loading device, a switch to select single or continuous garbage loading operation, a switch to select garbage loading operation and garbage discharge operation, a switch to operate the rotating plate 10 and the pushing plate 20 independently, and a switch to tilt and open the garbage bin 3, all of which are not shown in the figure.

As described above, the various switches are connected to the input side, while the output side (right side of Figure 4) of the control device PLC is connected to the solenoids SOLa to SOLd of the electromagnetic control valves V1 and V2. The control device PLC is programmed to output signals to the corresponding solenoids SOLa to SOLd based on the signals input from the switches SW1 to SW3, LS1 to LS5, etc., in order to operate the hydraulic motor 13, the pushing cylinder 24, etc. according to a preset procedure.

That is, for example, when the garbage loading device is operating to load garbage, the key switch SWK and the PTO switch SWP on the current carrying line K2 are both closed, and electricity is passed through the relay coil CR1. This closes the contact cr1 of the relay coil CR1, and electricity is passed through the current carrying line K3, so that the control device PLC becomes operable and outputs control signals to the solenoids SOLa to SOLd as appropriate.

In response to this control signal, solenoids SOLa to SOLd are excited, and the positions of solenoid control valves V1 and V2 are switched appropriately, supplying hydraulic pressure to the hydraulic motor 13, the pushing cylinder 24, etc. This causes the hydraulic motor 13, the pushing cylinder 24, etc. to operate, and the rotation of the rotating plate 10 and the oscillation of the pushing plate 20 are repeated in sync with each other, as described above with reference to Figure 2.

In more detail, first, as shown by the solid line in Figure 2, when the push plate 20 is at the forward limit position and an ON signal is output from switch LS1, and the rotating plate 10 is at the set stop position and an ON signal is also output from switch LS3, a control signal is output from the control device PLC that receives these signals, the solenoid control valve V2 is switched to the first communication position, and the hydraulic motor 13 starts normal operation. As a result, the rotating plate 10 starts to rotate upward.

After a predetermined period of time has elapsed, the control device PLC outputs a control signal to the solenoid SOLa of the solenoid control valve V1, switching the solenoid control valve V1 to the first communication position and causing the pushing cylinder 24 to begin contracting. This causes the pushing plate 20 to swing toward the rear trash inlet 4, and when the pushing plate 20 reaches its retraction limit position, an ON signal is output from the switch LS2.

In response to this, the control device PLC stops outputting the control signal to the solenoid SOLa, causing the solenoid control valve V1 to return to the neutral position and stopping the swinging of the pusher plate 20. While the pusher plate 20 is swinging, the rotating plate 10 continues to rotate, and scrapes the garbage into the garbage storage box 2. The rotating pusher plate 20 reaches the set stop position, and an ON signal is output from the switch LS3.

In response to this, the control device PLC stops outputting a control signal to the solenoid SOLc of the electromagnetic control valve V2, causing the electromagnetic control valve V2 to return to the neutral position and stopping the rotation of the hydraulic motor 13. The control device PLC also outputs a control signal to the solenoid SOLb of the electromagnetic control valve V1, switching the electromagnetic control valve V1 to the second communication position, and the pushing cylinder 24 begins to extend, causing the pushing plate 20 to begin swinging forward.

In this way, the pusher plate 20, which swings forward toward the trash storage box 2, pushes the trash on the rotating plate 10 into the trash storage box 2, and when it reaches its forward limit position, an ON signal is output from the switch LS1. In response to this, the control device PLC stops outputting a control signal to the solenoid SOLb, which returns the solenoid control valve V1 to its neutral position, and the extension operation of the pusher cylinder 24, i.e., the forward swing of the pusher plate 20, stops.

-Person recognition device and emergency stop device-
However, when the garbage loading device is operating to load garbage as described above, there is a risk that an operator who is loading garbage into the garbage inlet 4 may inadvertently be caught in the rotating plate 10, etc. Therefore, in the garbage collection vehicle 100 of this embodiment, the camera 7 is disposed so as to photograph the vicinity of the garbage inlet 4, and if it is determined by image processing that a person is in a dangerous area near the garbage inlet 4, the operation of the garbage loading device is immediately stopped.

That is, as shown in Figs. 1 and 2 above, and also in Fig. 5, a camera 7 is disposed at the top of the back of the trash bin 3, i.e., above the trash inlet 4, and photographs the area below near the trash inlet 4. The image data thus photographed is transmitted to an image processing unit 8 (an image processing device disposed, for example, near the driver's seat as shown by the dashed line in Fig. 1), which determines whether or not a person H is in the dangerous area (shown by hatching in Fig. 5) between the front edge 4a and the rear edge 4b of the trash inlet 4.

As described above, when the garbage loading device is in loading operation, both the key switch SWK and the PTO switch SWP are closed, and electricity is applied to the control device PLC via the power line K3. As shown in FIG. 4, an image processing unit 8 is installed in the power line K3, and if it is determined that a person H is in a dangerous area as described above, it cuts off the power to the control device PLC.

First, the method of human recognition using image processing will be explained below. As shown in FIG. 5, the image processing unit 8 is provided with a central processing unit CPU that executes a predetermined program to perform various controls, an image processing unit DSP that inputs image data from the camera 7 and performs known image processing such as that described below, a memory M that stores data used by the central processing unit CPU and the image processing unit DSP, and a relay switch SW4 that opens and closes in response to commands from the central processing unit CPU.

Although not shown, the image processing unit 8 also includes a buffer for temporarily storing various data such as images, and a camera control circuit that controls the camera 7 upon receiving instructions from the central processing unit CPU. In this embodiment, the camera 7 is a backup camera that allows the driver of the refuse collection vehicle 100 to monitor the rear, and the image processing unit 8 also includes an image output circuit that displays the results of image processing on the monitor.

- Image processing routine -
The image processing unit DSP is a general integrated circuit that performs known image processing logic at high speed, and performs, for example, a binarization process of input image data, a labeling process of regionalizing adjacent pixels in this binarized image data, a person identification process of identifying that the object image region regionalized by the labeling is a human image, and a person position determination process of determining whether the position of the object image identified as a human image is in a dangerous area.

Specifically, the image processing routine will be described with reference to the flowchart in FIG. 6. First, after starting, binarization processing is performed in step S1. For example, this is a process in which the brightness value of each pixel in the input image data is set to the maximum brightness value if it is equal to or greater than a preset threshold value, and is set to the minimum brightness value if it is less than the threshold value. The generated binary image data is one in which much of the effects of noise and changes in the amount of light have been removed.

Next, in step S2, a labeling process is performed. This is a process for dividing adjacent pixels in the binarized image data into regions; for example, multiple pixels that have the same luminance value and are close to each other within a specified distance are considered to be one region. The labeling process is performed on the entire image plane, and each region that is divided into one region is recognized as an object image.

Then, in the following steps S3 to S5, person identification processing is performed for each of the object images. In this embodiment, as described above with reference to FIG. 5, the camera 7 is disposed above the garbage inlet 4, and an image is taken of the area below the garbage inlet 4. Therefore, the image shows a large image of the head of person H, as shown in an example in FIG. 7, and also shows part of his face as seen from above. In other words, the image data also contains information about the face of person H.

First, in step S3, pre-set feature data for the head (including face), i.e., data indicating, for example, the size and shape of the head and the condition of the hair, is referenced, and an object image that satisfies the conditions of this feature data is provisionally determined to be the head of person H. Note that the feature data is obtained by taking images of the heads (including faces) of many people in advance and extracting features such as size and shape, and is stored in memory M of image processing unit 8.

Then, in steps S4 and S5, the object image tentatively determined to be a head is discriminated from other object images. First, in step S4, a change in the position of the object image is detected by differential processing (processing to find the difference in brightness value for each pixel) of multiple image data input in time series from camera 7. Then, this change in position, i.e., the distance traveled by the object image, is divided by the time required for this (the time interval for acquiring the image data) to calculate the moving speed of the object image.

Then, in step S5, it is determined whether the calculated moving speed is equal to or lower than a preset threshold value. This threshold value is set in advance through experiments, etc., so that the moving speed of the head of the worker who puts the trash into the trash inlet 4 can be distinguished from the moving speed of the trash being put in. Therefore, if the calculated moving speed is higher than the threshold value, the movement is too fast and it is identified as not being the head of person H, a negative determination is made (NO) and the routine is terminated (END).

On the other hand, if it is determined in step S5 that the moving speed is equal to or lower than the threshold (YES), the object image is identified as the head of person H and the process proceeds to step S6 to determine whether or not this object image is in a pre-defined dangerous area. This can be determined by whether or not the position coordinates of the pixels forming the outline of the area forming the object image are ahead of the boundary line B of the dangerous area (rear edge 4b of the garbage inlet 4).

Therefore, if it is determined that the object image identified as the head of person H is in a dangerous area (YES), the process proceeds to step S7, where a stop signal is output to the central processing unit CPU to stop the operation of the garbage loading device, and the image processing routine is terminated (END). On the other hand, if it is determined that the object image is not in a dangerous area (NO), the stop signal is not output and the image processing routine is terminated (END).

When a stop signal is then issued from the image processor DSP, the central processor CPU, which receives this, opens the relay switch SW4. In other words, by energizing the relay coil (not shown) to open the switch contacts, the power supply to the control device PLC through the power supply line K3 is cut off. This forcibly stops the operation of the control device PLC, so that even if there is some abnormality in the control device PLC, the power supply to all solenoids SOLa to SOLd of the solenoid control valves V1 and V2 is stopped.

As a result, all of the solenoid control valves V1, V2 in the first or second communication position are returned to the neutral position, and as a result, the operation of the hydraulic motor 13 and the pushing cylinder 24 is immediately stopped. In this manner, in this embodiment, the central processing unit CPU of the image processing unit 8 and the relay switch SW4 constitute an emergency stop device that stops the operation of the garbage loading device.

- Camera layout -
Next, the layout of the camera 7 will be described in detail with reference to Fig. 5. In this embodiment, in step S6 of the flow in Fig. 6, it is determined whether the position coordinates of the pixels forming the outline of the object image identified as the head of person H cross the boundary line B (rear edge 4b of the garbage inlet 4) and enter a dangerous area, and the camera 7 is disposed almost directly above the garbage inlet 4 to make this determination accurately.

In other words, as shown in an example in Figure 9, if the camera 7 is placed forward of the front edge 4a of the trash inlet 4, the optical axis A of the imaging lens 70 must be angled significantly from vertically downward to the rear in order to capture the trash inlet 4 below and the person H behind it. This makes it difficult to accurately detect the distance D between the rear edge 4b of the trash inlet 4 and the person H behind it on the image plane in the image captured by the camera 7.

More specifically, as shown in FIG. 9 above, when the tilt angle θ of the optical axis A of the imaging lens 70 from the vertical downward to the rear becomes large, even if the head of person H is about to enter the dangerous area (shown by hatching) above the garbage inlet 4 as shown in the figure, it appears as if there is a large gap D between the rear edge 4b (boundary line B) of the garbage inlet 4 and the head of person H on the image plane.

In this embodiment, the camera 7 is attached to the rear end of a stay 71 that extends rearward from the top of the trash bin 3, so that the center of the imaging lens 70 is located halfway between the front edge 4a and the rear edge 4b of the trash inlet 4 (almost directly above the rear edge 4b in the example of Figure 5) in a plan view (plan view from above, not shown). The camera 7 is attached to the stay 71 so that the orientation of the optical axis A of the imaging lens 70 can be adjusted.

With this layout, as shown in the figure, the optical axis A of the imaging lens 70 faces vertically downward when viewed from the side, passing almost through the rear edge 4b of the trash inlet 4, and the depth direction of the image captured by the camera 7 is essentially the up-down direction (vertical direction). As a result, as shown in Figure 5, if there is a gap D between the boundary line B of the dangerous area and the person H behind it, this gap D will appear as is on the image plane.

In other words, in the image shown in FIG. 7, the distance D between the boundary line B of the dangerous area and the head of the person H behind (the distance D in the vertical direction in FIG. 7) directly represents the distance D in the front-to-back direction shown in FIG. 5. Therefore, based on the data of this image, it is possible to extremely accurately determine whether or not person H has crossed the boundary line B and entered the dangerous area (the determination in step S6 of the flow in FIG. 6).

In order to make such an accurate judgment based on image data, it is not necessary to position the center of the imaging lens 70 of the camera 7 almost directly above the rear edge 4b of the garbage inlet 4 as described above. To obtain a sufficient effect, it is sufficient to position the center of the imaging lens 70 midway between the front edge 4a and the rear edge 4b of the garbage inlet 4 in a plan view. In this case, this also includes directly above the front edge 4a and the rear edge 4b of the garbage inlet 4.

This is because if the center of the imaging lens 70 were to be positioned behind the rear edge 4b, the camera 7 would protrude too far to the rear of the refuse collection vehicle 100, and the stay 71 would become too long, resulting in problems such as vibration. On the other hand, if the center of the imaging lens 70 were to be positioned ahead of the front edge 4a of the refuse inlet 4, the rearward inclination angle θ of the optical axis A would naturally become large, as described above with reference to Figure 9.

From the viewpoint of the accuracy of this determination, it is preferable that the center of the imaging lens 70 is located rearward from the center of the front edge 4a and rear edge 4b of the garbage inlet 4. Then, by pointing the optical axis A of the imaging lens 70 vertically downward or tilting it slightly rearward toward the rear edge 4b of the garbage inlet 4, it is possible to accurately and quickly determine that person H has entered a dangerous area, in a manner similar to the above embodiment.

On the other hand, as an example, as shown in FIG. 8, the center of the imaging lens 70 may be positioned forward from the center of the front edge 4a and rear edge 4b of the garbage inlet 4 (almost directly above the front edge 4a in the example of FIG. 8). In this case, too, it is preferable to tilt the optical axis A of the imaging lens 70 backward from the vertical downward direction, and point it toward the rear edge 4b of the garbage inlet 4. This has the advantage that more information about the face is included in the image, making it easier to identify that it is person H.

In addition, the larger the rearward inclination angle θ of the optical axis A of the imaging lens 70, the wider the field of view of the camera 7 becomes toward the rear of the garbage collection vehicle 100, which is advantageous in sharing it with the backup camera. However, as described above with reference to FIG. 9, the larger the inclination angle θ, the more likely it is that it will take a long time to determine that person H has entered a dangerous area. In this case, the boundary line B set in the image may be set slightly behind the rear edge 4b of the garbage inlet 4.

As described above, in the person recognition device of this embodiment, the imaging lens 70 of the camera 7 arranged above the garbage inlet 4 at the rear of the garbage collection vehicle 100 is positioned almost directly above the rear edge 4b of the garbage inlet 4, and its optical axis A is directed almost vertically downward, so that in the captured image, the distance D between the boundary line B of the dangerous area and the person H at the rear almost directly represents the actual distance D in the front-to-rear direction.

Therefore, by using known image processing technology, it becomes possible to very accurately determine whether or not person H is in a dangerous area, and by stopping the operation of the garbage loading device based on the result of this determination, it is possible to reduce the frequency of unnecessary operation stoppages caused by erroneous determinations, prevent a decrease in convenience, and ensure sufficient safety.

In addition, in this embodiment, the object images contained in the image that are determined to be a "head" are identified as to whether or not the object is the head of person H based on the moving speed of the object image, improving the accuracy of identifying the object image from the trash inserted into the trash inlet 4. And, as described above, the fact that the moving direction (forward and backward directions) of person H is displayed on the image plane is also advantageous in accurately calculating the moving speed.

Furthermore, in this embodiment, when the refuse collection vehicle 100 is viewed from the side, the optical axis A of the imaging lens 70 of the camera 7 passes through approximately the rear edge 4b of the refuse inlet 4, so that this rear edge 4b, i.e., the boundary line B between the safe area and the dangerous area, appears approximately in the center of the image as shown in FIG. 7. Therefore, there is also the advantage that the distance D between the boundary line B and the person H behind is less susceptible to distortion of the optical system of the camera 7.

-Other embodiments-
Although the preferred embodiment of the present invention has been described above, this is merely one specific example and does not limit the present invention, so that the specific configuration can be appropriately changed in design, etc. For example, in the above embodiment, the image processing unit 8 is provided in the current supply line K3 to the control device PLC, and the current supply to the control device PLC is cut off by opening the relay switch SW4, but the present invention is not limited to this.

That is, for example, when the image processing unit 8 determines that person H is in a dangerous area, it can output a stop signal to the control device PLC, which in turn can stop the output of control signals to the solenoids SOLa to SOLd of the electromagnetic control valves V1 and V2. Any other configuration that can stop the operation of the garbage loading device can be used.

In the above embodiment, when the image processing unit 8 receives a stop signal from the image processing unit DSP, the central processing unit CPU opens the relay switch SW4, but this is not limited to the above. For example, the signals from the limit switches LS4 and LS5 for detecting the operating state of the rotating plate 10 of the garbage loading device may be input not only to the control device PLC but also to the image processing unit 8, and the relay switch SW4 may be opened when the rotating plate 10 is in the dangerous angle range Z (see FIG. 2) and the head of the person H is in the dangerous area.

In other words, even if the garbage loading device is in operation, when the rotating plate 10 rotates outside the dangerous angle range Z, there is no risk of part of the worker's body being caught in it, so even if person H is in a dangerous area at that time, the operation of the garbage loading device is not stopped. This further reduces the frequency of unnecessary operation stops of the garbage loading device, improving convenience.

Furthermore, in the above embodiment, the present invention is described as being applied to a garbage collection vehicle 100 equipped with a so-called rotary garbage loading device, and the main part of the garbage loading device is composed of a rotating plate 10 and a push plate 20, but this is not limited to this, and the main part of the garbage loading device may be composed of a lifting plate and a push plate, and the structure is not particularly limited.

REFERENCE SIGNS LIST 100 Refuse collection vehicle 1 Vehicle chassis 2 Refuse storage box 3 Refuse input box 4 Refuse input port 4a Front edge 4b Rear edge 7 Camera 70 Imaging lens 8 Image processing unit (image processing device)
10 Rotating plate (loading member, garbage loading device)
13 Hydraulic motor (garbage loading device)
20 Push plate (garbage loading device)
24 Pushing cylinder (garbage loading device)
A Optical axis of the imaging lens CPU Central processing unit of the image processing unit (emergency stop device)
SW4 Relay switch for image processing unit (emergency stop device)
LS4, LS5 Switch (sensor for detecting that the loading member is operating near the garbage inlet)

Claims (1)

A person recognition device that is installed on a garbage collection vehicle having a garbage dump box at the rear of the vehicle chassis and a garbage loading device that is provided in the garbage dump box and can load garbage into the garbage storage box, and recognizes a person near a garbage dump opening that opens along the back surface of the garbage dump box from a front edge portion to a rear edge portion that is located rearward of the front edge portion of the garbage dump box,
A camera disposed outside the trash bin and above the trash inlet;
an image processing device that inputs image data captured by the camera so as to include the rear edge and determines whether or not a person is present in a dangerous area set on the front side of the vehicle with the rear edge of the garbage inlet, which is located forward of the rear end of the vehicle in the image, as a boundary;
an emergency stop device that stops the operation of the garbage loading device when the image processing device determines that a person is present in the dangerous area;
The camera is attached to a stay on the upper part of the trash bin so that an imaging lens is located midway between the front edge portion and the rear edge portion in a plan view, and so that the direction of the optical axis of the imaging lens is adjustable;
The method is configured to determine whether the loading member of the garbage loading device is operating in a dangerous range where there is a risk of entanglement of a body part of a person in the garbage bin,
The emergency stop device is configured to stop operation of the garbage loading device when the image processing device determines that a person is present in the dangerous area and that the loading member is operating within the dangerous range.This is a person recognition device for a garbage collection vehicle.

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