The list of software used on the device side this time is summarized below.
- Raspbian OS where AWS IoT Greengrass can be installed
- Python
- AWS IoT Greengrass About AWS IoT Greengrass
| No. | Parts image | Item name | Usage | Approximate unit price | Required quantity | Subtotal | Where to buy and product page | Consideration for product selection |
|---|---|---|---|---|---|---|---|---|
| 1 |  |
Refrigerator | Product shelves | $320 | 1 | $320 | Amazon.com | Refrigerator |
| 2 |  |
Raspberry Pi set | Device control | $100 | 1 | $100 | Amazon.com | |
| 3 |  |
USB camera | Product recognition | $100 | 2 | $200 | Amazon.com | Camera |
| 4 |  |
QR Code Scanner | Read QR Code | $50 | 1 | $50 | Amazon.com | |
| 5 |  |
LED Panel | Fridge interior lighting | $20 | 4 | $80 | Amazon.com | White is preferable to yellow. Prepare the number of steps x2 |
| 6 |  |
Electromagnetic lock | Door unlocking / locking | $16 | 1 | $16 | Amazon.com | |
| 7 |  |
DC power supply | Lighting and door lock power supply | $20 | 1 | $20 | Amazon.com | Recommended voltage is 12V and current value is 8A |
| 8 |  |
Relay Module | Door lock and lighting control | $8 | 1 | $8 | Amazon.com | |
| 9 |  |
Magnetic sensor | Door open / close detection | $7 | 1 | $7 | Amazon.com | |
| 10 |  |
Strong double-sided tape | Parts installation and fixing | $6 | 2 | $12 | Amazon.com | |
| 11 |  |
Color Vinyl Tape | Wiring fixing | $12 | 1 | $12 | Amazon.com | Select color to match fridge interior |
| 12 |  |
JST-SM Connector Wires | Wiring creation | $8 | 1 | $8 | Amazon.com | |
| 13 |  |
JST-SM Connectors | Wiring creation | $8 | 1 | $8 | Amazon.com | |
| 14 |  |
Crimping tool | Contact crimping | $20 | 1 | $20 | Amazon.com | |
| 15 |  |
Wiring material | Electrical wiring | $12 | 1 | $12 | Amazon.com | |
| 16 |  |
Wire stripper | Wiring material stripping | $12 | 1 | $12 | Amazon.com | |
| 17 |  |
Heat Shrink Butt Connectors | Connecting wires | $12 | 1 | $12 | Amazon.com | Stranded cross-sectional area: 0.3 ~ 1.65 |
| 18 |  |
Pliers | Crimping sleeve crimping | $9 | 1 | $9 | Amazon.com | Avoid long nose pliers |
| 19 |  |
Solder and soldering iron | Soldering of light panel wiring | $22 | 1 | $22 | Amazon.com | Only a few places are soldered, so a small amount is enough |
| 20 |  |
Hot Glue Gun | Insulation of lighting wiring | $13 | 1 | $13 | Amazon.com | |
| 21 |  |
Digital multimeter | Debugging electrical circuits | $13 | 1 | $13 | Amazon.com | It is desirable to have a continuity check function |
| 22 |  |
Screwdriver set | Various | $17 | 1 | $17 | Amazon.com | |
| 23 | Target products | Products that will be made available for vending | $0 | Target products | ||||
| Approximate amount of money | $959 |
When selecting products, it is necessary to carefully consider the combination of refrigerator, cameras, and target products.
For this solution, we have developed a method to identify products by detecting objects in camera images. Therefore, the part where the product can be detected must be within the angle of view of the camera. In order capture photos of the top surface of the products from the ceiling, you must set the camera so that all products in the refrigerator plane are captured within the camera angle of view. If the refrigerator has two shelves, even if you use a wide-angle camera with an angle of view of 120 degrees, you may not be able view the cap of a 500ml bottle if they are near the edges. If you limit it to smaller products, you can use multiple shelves.
As mentioned earlier, these factors need to be considered carefully, but the individual selection criteria are listed below.
Below is a summary of the desirable and undesirable items when choosing a refrigerator.
The interior of the refrigerator is a light color such as white. The reason is that it is bright because it reflects light easily and it is easy to catch the product clearly.
- The interior of the refrigerator is a dark color such as black. The reason is that it gets dark and the product is hard to see. A possible workaround is using more light panels.
- Glass door The reason is that a large amount of outside light enters and the shooting environment is not stable. As a result, the accuracy of inference may decrease. This could be solved by covering or applying some kind of tint to the glass.
- Large cross section. The reason is that although the capacity increases, the range that must be covered increases accordingly, so it is necessary to provide a greater distance between the camera and the product. It may be possible to solve this problem by providing a partition to divide the left and right sides of the shelf and by installing one camera for each side.
If you use a refrigerator with a large bottom area that minimizes dead space in the refrigerator, installing a wide-angle camera is an option. Wide-angle cameras, on the other hand, cause large distortions, especially near the sides of the image. Therefore, if you use a camera that is too wide, the top label of the product placed on the edge or corner of the refrigerator will be greatly distorted, which will affect the recognition and detection of the product. By taking a product image placed at the edge or corner of the refrigerator and including the distorted image in the training data, we think that it is possible to recognize the product under such conditions, but the points to consider will increase. Please consider these when selecting a camera.