Proposal for Pet Sheet Installation System

In recent years, more and more people have been keeping pets. Many zoonotic diseases now exist, and it is possible to become infected with zoonotic diseases from pets. One of the routes of infection is through excrement. Therefore, we have developed a device that automatically folds pet sheets. This system consists of two parts: a camera part that detects excrement and a part that processes the excrement. When the system recognizes that the pet has defecated through image processing, it automatically folds the pet sheet along the creases and opens the lid of the trash can for disposal. When the pet gets on the device to defecate, the system saves the image taken just before as a background, and when the pet gets off the device after defecating, the system recognizes the excrement and folds the left and right sides of the pet sheet, then the top and bottom. Then, the pet sheet is lifted to the front of the trash can and the lid of the trash can is opened using a DC motor. Finally, the pet sheet is thrown into the trash can, and the operation is completed by returning the arm and the trash can lid to their initial positions. The success rate of the experiment was 100% for the recognition of excrement and 100% for the disposal of excrement.


Introduction
In 2020, WHO declared a pandemic due to COVID-19, and the number of infected people and deaths is increasing day by day (1).
There are more than 200 infectious diseases known to WHO, and new infectious diseases are expected to occur in the future (2~4) .
According to the "National Survey of Dog and Cat Ownership" conducted by the Pet Food Association of Japan, as of December 22, 2021, there were approximately 7,106,000 dogs and 8,946,000 cats in captivity, indicating that we coexist with many animals (5) .In addition, as of October 1, 2021, there are 861 guide dogs, 57 service dogs, and 61 hearing dogs, making them indispensable in the lives of people with physical disabilities (6) .
Under these circumstances, preventive measures are very important to prevent the spread of zoonotic diseases.
The main routes of transmission are direct transmission and indirect transmission (7) .Direct transmission refers to infection from animal bites, scratches, feces and droplets.We focused on the method of transmission by wind-borne inhalation of pathogens contained in feces.The Ministry of Health, Labor and Welfare recommends that excrement should be disposed of promptly to prevent infection (8) .However, it is not practical to dispose of excrement every time a person defecates.Therefore, a product called "Brilliant Pad Smart" is available (9) .In this product, pets defecate on a roll of sheets, and the sheets are rolled up at regular intervals.This means that pets can be disposed of without touching the excrement, and the risk of contracting zoonotic diseases is reduced.However, there are some disadvantages.The first is that excrement remains in the device until one roll is used.One roll of these pet sheets is equivalent to 27 regular-size pet sheets, and it takes one to two weeks to finish a roll.Secondly, if the pet does not defecate at a certain place in the sheet, there is a possibility that it will be missed.
To solve this problem, we have developed a system that automatically disposes of pet sheets after confirming that the pet has defecated through image processing.However, once a pet sheet is discarded, a new one cannot be installed, and the pet owner cannot be absent for a long time.Therefore, we developed a fully automatic pet sheet changing system with an additional function to install new pet sheets.This system first performs image processing using a camera to recognize three things: that the pet has gotten on the device, that the pet has gotten off the device, and that excrement remains on the device.Once the excrement is identified, the system folds the pet sheet in the order of left to right, top to bottom.Then, using a DC motor, the lid of the trash can is opened and the pet sheet is carried to the trash can for disposal.After all the parts are returned to their initial positions, the pet sheet installation system installed

Proposal for Pet Sheet Installation System
Figure 1 shows the configuration of the device created in this study.This system consists of three parts: a pet sheet disposal system, an image processing system, and a pet sheet installation system.The top view of the whole system is shown in Fig. 1(a).The installation system is located to the left of the disposal system, and the camera for image processing is installed above the trash can.
The first stage of the disposal system consists of seven servo motors to fold pet sheets as shown in Fig. 1(a).The first stage of the installation system is designed so that the pet sheets can be moved to the disposal system by casters.The casters are moved by winding a wire.The second stage of the disposal system consists of a power supply, Arduino, DC motor, and motor driver as shown in

Image Processing
When the distance sensor detects that a pet has entered the device, the system saves the image before the pet entered the device as a background.When the distance sensor detects that the pet has gotten off the device, it starts image processing using the camera.First, the image after the pet gets off the device is saved.
To preserve only the part of the image to be processed, a perspective projection is performed.Next, we grayscale the image for binarization.Differentiate the grayscaled image from the pre-stored background.The detected difference is binarized.
The image is enlarged and reduced twice to remove noise.The image is enlarged twice to return it to its original size.Assign a number to each chunk of the remaining differences.Small areas are removed, and the remaining ones are recognized as excrement.Finally, it determines the center of gravity, automatically starts folding the pet sheet to the right of the center, and disposes of the pet sheet in the trash.

Disposal Action
The pet sheet is folded as shown in  5) and ( 7), as shown in Figure 2(f).Then, move the pet sheet to the plate at the back while holding it between ( 5) and ( 7).

Installation Action
First, after completing the disposal operation, the distance sensor for detecting pets is folded using a servo motor because it gets in the way when disposing of the pet sheets.As shown in Fig. 3  Since there is a pillar at the limit of the movement of the caster, the infrared LED will be blocked by the pillar and will not be able to reach the infrared sensor when it reaches the pillar.
When the infrared LED cannot reach the infrared sensor, the movement of the caster is stopped.The caster is pulled by a wire that is hooked to the servo motor and rewound, just as the fan is moved.When the caster arrives at the top of the disposal section, it rewinds the wire as shown in Figure 3(f) to place the pet sheet on the disposal section.The fan output is turned off, and the wire is wound up again as shown in Figure 3(g), and the pet sheet is placed on the disposal section.The operation is completed by reversing all the operations.

Prototype
In this section, we describe the prototype that realized the system described in Chapter 2. The overall view of the system we produced is shown in Figure 4. shows the side view of the installation system, Figure 4(f) shows the side view of the disposal system, and Figure 4(g) shows the front view.The size of the whole system is about 920W × 590D × 380H (mm), the size of the disposal system including the camera of the image processing section is about 450W × 570D × 380H (mm), and the size of the installation system is about 590W × 450D × 310H (mm).The power and threshold values of the image processing section and disposal system section are the same as those of the past prototype.In order to prevent pet sheets from getting caught in the trash can, we changed the trash can to a square one and used Omron's W2DG-E01 as a sensor to confirm that the trash can is open.The installation system consisted of four fans, three servo motors, and four photo interrupters.
The system for installing the pet sheets used FEETECH's FS5106R for all the rotation servo motors that pull the wires.A San Ace B97 from Sanyo Electric Co. was used as the fan to suck up the pet sheets.The sensor that controls the movement of the casters is S2506-02 from Hamamatsu Photonics.Another servo motor (S03T2BBMG/ GWS) was installed so that the caster can be tilted by 85 degrees when the pet sheet is placed.
The image processing and disposal operations of this prototype are as in our previous experiments (10) .
The installation operation is as follows.The sensor that recognizes the intrusion of pets is housed by a servo motor attached to the bottom, and the pet sheet is sucked up by a fan as shown in

Experiment
To verify the operation of the system, the operation of the installation system was checked in Section 4.1, and the operation of the entire system was checked in Section 4.2.

Installation action
We tested whether we could place 10 pet sheets on the disposal system in a row, and as shown in Fig. 6, all of the tests were successful.

Overall operation
After confirming the intrusion of pets, the system recognized the excrement by image processing, folded and discarded the pet sheet, and tested whether a new pet sheet could be placed on the sheet.
The time required for the system to return to the initial position after the excrement was left behind was 1 minute and 20 seconds, which is practical.

Conclusion
In this study, we developed a fully automatic pet sheet changing system.The developed system can automatically fold pet sheets, dispose of them, and install new sheets in 1 minute and 20 seconds using a camera.This allows the user to quickly dispose of the pet sheets without touching them.In addition, the lid of the trash can be automatically opened and closed to prevent the spread of bacteria contained in the excrement over time.In addition, at least 10 replacement pet sheets can be replaced automatically, so the system can be used even when the user is out.Thus, the system can reduce the burden on the user and greatly reduce the risk of infection by zoonotic diseases.
In the future, we aim to add a function that allows the user to take and save pictures of excrement and attach them to e-mails so that the state of excrement can be checked.
DOI: 10.12792/iciae2022.015 next to it is used.Several sheets of pet sheets are replenished in advance, and a fan suspended by wires at the top is lowered to suck up the pet sheets.A fan suspended by a wire is lowered to suck up the sheets, and the sheets are moved to a disposal device using casters.When the fan is stopped, the pet sheets are sucked up.When the output of the fan is stopped, only the PET sheets remain in the disposal unit and are placed there.Wind up the wire and return the caster to the initial position to complete the operation.The same operation is repeated when the pet defecates again.

Figure 1 (Fig. 2 .
Figure1(b).The back side of the second stage of the installation system consists of a wire wrapped around a servo motor as shown in Figure1(c).This wire is wound up to raise and lower the fan shown in Figure1(d), which is the back side of the third stage.The fourth stage of the installation system is designed so that the pet sheets can be moved to the disposal system on casters as in the first stage, as shown in Figure1(e).Therefore, the casters are moved by winding the wire as well.These are used to move the first stage, and the upper casters are used to move the second stage.Figure1(f)shows a side view of the disposal system.The numbers in Figs.1(a) and 1(f) indicate the servo motors.Figure1(g) is a side view of the installation system.The user opens and replenishes about 10 pet

Figure 2 .
As shown in Figure 2(a), fold down (1) and fold the Pet Sheet.After returning (1) to its original position, raise (1) to the right angle again to prevent the pet sheet from shifting.Fold down (2) as shown in Figure 2(b), and fold the sheets.Return (2) to its original position as before, and then raise (2) again.If the image processing determines that the excrement is on the right side, the folding starts from the right side.To make folding easier, tilt (3) as shown in Figure 2(c).The folding of the central part is done as follows.Tilt (4) as shown in Figure 2(d), and fold the pet sheet.Since the Pet Sheet expands by absorbing urine, do not put back (4) as shown in Figure 2(e), and fold the Pet Sheet by putting down (5).Return (3) and (4) to their original positions.Move the pet sheet to the plate at the back of the center to discard it.To prevent the pet sheet from shifting, stop the machine once at an angle where the pet sheet is vertical, sandwiched between (

Figure 3 (
Figure 3(c), the pet sheets are moved by the casters in the lower section.At this time, the pet sheet is moved to the center of the disposal unit as shown in Figure 3(d).Next, use the upper casters to move the pet sheet to the top of the disposal unit perfectly, as shown in Figure 3(e).Since there is a pillar at the limit of the movement of

Figure 4 (
Figure 4(d) is the fourth stage of the installation system.Figure 4(e)

Fig. 5 .
Fig. 5. Operation of the prototype of the installation system.

Fig. 5 (
Fig.5(a) and lifted by a wire as shown in Fig.5(b).First, the casters at the bottom of the installation system are pulled by the wire and moved to the center of the disposal system, as shown in Figure5(c).Next, move the upper casters to the end of the disposal system by pulling them in the same way as shown in Figure5(d).Use the wire connected to the fan to lower the fan and lower the pet sheets into the disposal system, as shown in Figure5(e).Turn off the output of the fan and lift up the fan only by the wire as shown in Figure5(f), and the installation of the pet sheet is completed.The entire process of the installation system is reversed, and the fan and the sensor for checking the entry of pets are returned to their initial positions to complete the operation..