I have a son of 10 who keeps forgetting his school bag in the school.
I am planning to construct an arduino-based solution that will have a device that will be carried in his school bag and another in his pocket.
The device in his pocket will sound a warning alarm when the distance between the 2 devices gets over a certain limit. Say 4 meters (12 ft).
I looked into several approaches;
-A pair of ultrasonic sensors used as a transmitter (in the school bag) and a receiver (in the pocket) could do the job but will not work if there are obstacles between the 2 devices. Furthermore they are not omnidirectional.
-An infrared solution will have the same problems plus distance limitations
-Two GPS captors will need a data link to communicate. They may also be problematic if the bag is in a locker.
Would you be kind enough to let me know of what you think?
I repeat the constraint.
Distance between the 2 devices= 4 to 10 meters.
The devices will need to communicate omnidirectional.
The devices could have obstacles between them.
They have to be childproof. But that is another issue!
I thank you in advance.