Group SD0602
From ECE Department Wiki
Contents |
Members
- Toby Johnson
- Craig Thingvold
- Advisor : Dr. Jake Glower
Project Description
This is the Door monitor project. We are working with the Anne Carlsen Center to develop a device which should alarm workers when certain children walk through a door to go outside. Some children need to be supervised at all times and are not allowed to go outside without that supervision. Our project would ensure that these children would not go outside without the proper supervision.
Our design initially was going to consist of passive tags which would be acivated by readers at the exits. This approach is similar to the Electronic Article Survalence (EAS) Systems that are currently in use in many department stores. This approach was not giving us the distance that we needed. Our new design is very similar to the previous design except it incorporates an active tag. We feel that this is a much better design because it will give us the distance we need and it will be more reliable for the customer.
Options Considered
We started by researching many different approaches. A scanner/barcode system was one of the options researched. This would be similar to what is seen in a retail store where items are tagged and scanned by a laser. These tags hold information about the product. This option would not work well in our project because of the precise location of the tag to be read by the scanner. The next option explored was to incorporate proximity sensors with tags. These sensors would detect metal tags and alarm workers of the tag presence. This option would also not work well in our design because these sensors would detect a wide range of metals. The sensors would detect the metal tags, but would also detect many other metal objects that went through the doorway. Another option that we researched was Electronic Article Surveillance (EAS) systems. These systems are typically used in retail stores and are designed to sound an alarm when a tag that was not deactivated passes through the door. Another option considered was the new technology with RFID readers and tags. Much of the RFID theory was found on Microchips' Webpage at http://ww1.microchip.com/downloads/en/devicedoc/21299e.pdf. The reader is a complex design that sends and receives signals from a passive tag. These tags are able to hold and communicate information to the reader. This is an option that seems to fit our project well, but our challenge is to simplify this to our needs. For the project we will be using the EAS principles with magnetic coupling and the passive RFID tag design to satisfy our requirements. Our receiver is going to transmit a signal through an induction coil (antenna) which will power a tag through another induction coil (antenna). These induction coils function as a weakly coupled transformer that induces a voltage in the secondary coil. The following block diagram shows this reader design functions.
This door monitor will be able to sound an alarm when a tagged child enters the doorway. This will alert the staff that a child is leaving. The reader will use a combination of RFID and EAS Systems. Using electromagnetic theory we will be able to induce a voltage in the tag circuit. This induced voltage will power the tag allowing it to communicate with the reader. Once the reader detects a tag it will sound the alarm. The total budget for this project is anticipated to be approximately $650.
Requirements Capture
Introduction:
The objective of this project is to build a door monitor for the Anne Carlsen Center for Children. This is an NSF project. As of right now they have an alarm on the doors, but are looking for a way to monitor the doors without a buzzer going off every time that the door opens. Also, there are certain children who are allowed to leave and certain children who are not allowed to leave. They are giving us the “ok” to “tag” these children, i.e. a small tag on the child’s belt loop or shirt.
Requirements:
• The staff must be notified when tagged children walk through the door.
• Tags must be inexpensive so they may be replaced easily if lost or broken.
• Transmitter must be small and lightweight enough to fit on a child’s belt loop or shirt, but also durable enough to handle every day wear and tear.
• If it is an active transmitter, the battery must last for a significant amount of time.
• Alarm can be tripped only when the child is walking through the threshold of the door.
• If using magnetic detector, cannot jeopardize the health equipment for the safety of the patients.
• Tags and exposed receiver must not have any sharp edges for the safety of the patients.
• The staff must be able to operate the device easily (user friendly).
• The receiver must not disrupt the flow of hallway traffic.
• Receiver must be able to read many tags
• Receiver requires a status indicator so the staff knows it is on.
Summary:
We have spoken to Todd Kollman, who is the adaptive equipment engineer. He has tried a few things to help with this problem. He is currently using a duck decoy which he has modified for the process and would like a better solution. Our ideas include an Electronic Article Surveillance system similar to the Wal-Mart and Target anti-shoplifting systems now in place. Using the surveillance system, we could tag the children with these small devices and an alarm would go off as soon as they enter the door.
Another idea is to use the RFID tags such as the Alien Technology tags being used for cattle right now. Using this technology, we could not only tell when just one of them has left the building, but also exactly who left and exactly where they are at. Although this is not a requirement, it would be helpful for the staff to know if an emergency should come up.
Keywords
- RFID (Radio Frequency Identification)
- EAS (Electronic Article Survelance)
- Induction
- Reader
- Tag
