Multiple Arduinos connected to Android device

I have 16 Temperature Controllers which are Arduino UNO based and are currently communicating (sending temperature data) to a PC using RF22 radios.
My intention is to use an Android based tablet as the human interface in place of the PC and to use the USB port of the tablet connected to the 16 Temperature Controllers in place of the RF22 radios.
My question is:
Is this possible - connecting the 16 Arduino Unos via a single USB port?
If so, could someone steer me in the right direction as to what additional hardware (shields) I would require on the Arduino Uno side.
If not, could someone recommend an alternative approach to accomplish this.

Declan:
Is this possible - connecting the 16 Arduino Unos via a single USB port?

The first problem is about an Android app capable of handing sixteen sources on the USB port - Android problem.

I imagine it would be somewhat simpler to have one Uno connected to Android and collecting the the data from all the others.

Since you are dispensing with the radios, I wonder why you need sixteen Unos.

I run two arduinos connected to a USB hub, so you probably could daisy chain several hubs. Note, power from the USB source might be an issue with 16 arduinos connected.

Thanks for the prompt replies.

I imagine it would be somewhat simpler to have one Uno connected to Android and collecting the the data from all the others.

If I had to use one Uno that is collecting the data from the 16 Unos and connected to the Android, how would I have the 16 Uno based controllers connect to the Uno that is collecting the data?

Since you are dispensing with the radios, I wonder why you need sixteen Unos.

I must have the 16 Unos as each temperature controller is a stand-alone unit and has 1 Uno

Declan:
Thanks for the prompt replies.
If I had to use one Uno that is collecting the data from the 16 Unos and connected to the Android, how would I have the 16 Uno based controllers connect to the Uno that is collecting the data?

Perhaps some register device on the serial port. I would assume that the Uno connected to Android also has a temp device, and polls fifteen others.

I must have the 16 Unos as each temperature controller is a stand-alone unit and has 1 Uno

Really? It seems a hell of a waste of Unos. If you were using radio comms, I would understand it, but I gather you intend to scrap the radios, so a better explanation might be in order. So what is this "temperature controller" you are talking about, how many wires does it need, and what is the geography?

Do not cross-post. Other thread removed.

Perhaps an RS485 (half-duplex) shield would help? It can do multi-point, but there are a lot of details to understand, I think it's worth having a look.

The master Arduino can be an Arduino Mega Adk, an special arduino for android development.
The slaves arduinos can be connected with rs485.