Multiple digital proximity sensors with wireless ethernet connectivity

G'day everyone,

I'm an absolute novice when it comes to Arduino technology, so please bear with me.

I'm designing a 'smart' tooling system for the workplace, whereby a user swipes their car to unlock the toolbox. Upon unlocking, the user can remove a tool from the pegboard. The proximity sensor (inserted into the pegboard underneath the tool) will register that the tool is no longer there, and assign that tool to that user.

There are several of these toolboxes in use, each of which needs to connect to a central computer which updates the list of people with swipe card access.

I think I'm alright in terms of the swipe card reader and the linear actuator for unlocking the toolbox, I'm just not sure what Arduino to choose to accommodate the sensors and wireless capabilities. I could go with the EtherMega which offers 54 digital I/O channels for 54 sensors, and also has the Ethernet out (which would go into a wireless router for connecting to the central computer). However, these boards are quite expensive. For about a quarter of the price, I could get an Arduino-compatible ATMEGA2560, which also has 54 digital I/O, and pair it with the Ethernet/SD card shield. I'm thinking that I could use the Ethernet from that to connect wirelessly with the central computer, and perhaps store the current access list on an SD card?

Does this all sound pretty farfetched or fairly reasonable? It's seems to make sense in my head!


Edit: I forgot to ask as well, can any recommend a good digital sensor for this purpose?

Does anyone have any ideas? I may be able to dismiss the wireless component entirely and keep the required data on the SD card. I spoke to my professor yesterday about proximity sensors, and he recommends using IR, which is what I had initially thought as well.

I'd like to use cheap analog IR sensors, but the most analog inputs I have found on an Arduino board is 16, so I'm not sure how to go about it.

You can use multiplexing chips like below to expand the number of analog inputs to a board. If the tools are hanging on a peg board, then I'd just look at turning the pegs into limit switches to detect when a tool is hanging and not.