We will make a smart backpack that can keep track of the contents, and learn when you are forgetting something. It will use an RFID system with small and easy to place tags to figure out when you place something in it. The backpack systems will also integrate with your smartphone through an app that you can use to check the items in your bag. You can even set the app to remind you to add something to the bag according to a preprogrammed schedule. Data from several sensors will be streamed to your smartphone to keep track of the conditions of your belongings and to make sure that they have not been subjected to any physical shocks or high temperatures.
We will be adding a battery pack and power management system so that you can safely charge your devices on the go. While you can use the app to keep track of your batteries’ energy level, we are also adding a screen to the outside of the bag to quickly check the backpack’s status.
1. Uses RFID to track the objects being put inside the bag
2. Contains a power system for users to charge portable devices
3. Uses internal sensors to warn the user of any shocks or temperature spikes that might affect their belongings
4. Backpack should be well designed
5. Summary of state should be displayed on a screen
6. Integrate with Android smartphone application to present tracked RFID and sensor data to users
The RFID system needs to be able to read the tags from items as they are placed into the pocket of the backpack. These reads must take place accurately, and with minimal extra effort by the user. The users will have to place the tags on their items, meaning that these tags must be small and minimally invasive. Additionally, we cannot control the material that the users will place these tags on, meaning that metal items that disrupt RF fields might be present. It is necessary for us to be able to read multiple tags simultaneously since we do not know how users will place items into their bags.
Due to our requirements, we ruled out using UHF systems since they have expensive readers and provide high data rates at ranges of over 1m, neither of which are useful for our application. The next two systems, LF (100-150kHz) and HF (13.56Mhz aka NFC) were closer to our design requirements.
HF or NFC systems allowed us to detect multiple tags and scan through some thin materials. However, the drawback of this was an operating range of around 6cm. These systems were well documented and had breakout boards, tags, and antennae readily available. This would require users to “check in” each item that they put into their bag using a scanner at the top of the pocket.
On the other hand, LF systems had higher ranges that would likely cover the inside of the pocket. The drawback to this approach is that multiple passive tags interfere with each other. This tag-collision can be avoided by using active tags, which have their own power supply and IC, but this would increase the cost and complexity of maintenance for users.
For the power system the battery is the primary feature. The goal is to get good battery life, low weight, and moderate output abilities. In order to gain these features we are willing to pay slightly more money and accept slower charge times. We need to ensure that DC to AC converters are fairly efficient. Research suggest that this can be done with a fairly simple PCB inverter. Most off the shelf components of this type are 12VDC to 120VAC.
The most important features are low power usage and low cost. Processing requirements will be minimal. However, considering this is not a primary feature we plan to use a raspberry pi for processing as this will greatly increase our prototyping and development speed. Moreover, the cost is reasonable. Additionally, even with a raspberry pi initial calculations indicate that this will be a very minor drain on the battery. Later we may develop a custom PCB using a Atmega328 to decrease production cost and power usage further.
The actual backpack itself has to be comfortable, spacious, and rugged. It should be easily retrofitted with components, and be able to resist environmental factors.