EW Project 2: Development stage 1 - The components

The idea was to modify this shared environment to be able to accommodate different people, and do do this we needed to profile different people as they sit and begin their day. We dabbled around using different methods of profiling. A weight-sensor on a chair that was calibrated the users was one of the discarded ideas. We settled on profiling using the individuals' drink receptacles; when working we established that each individual has their own mug/glass. We thought a good way to implement this would be using RFID stickers, or tags stuck to the bottom of each mug/glass. The RFID reader would be disguised inside an object you'd expect to find in an office environment - the coaster. To the user this would, in theory, appear seamless. They take their usual mug, and place it on a coaster. This everyday action would profile the user.

Unfortunately there were no available RFID readers in the DAT supply cupboard. We thought the idea was sound, so we wanted to keep the mug and coaster thing. Doing a little bodging I managed to create a ' coaster' from the transparent lid of some cotton buds, duct tape, and a light dependent resistor from a Real Robots kit I had lying around at home. The coaster could detect the transparency of the object on top of it. We got it to reliably detect two profiles, a mug and a glass. This worked very well due to the opacity of the mug, and total lack thereof of the glass.

A professionally constructed profile detection coaster.

The next step would be to create the activation system. In the previous post we identified that slamming your head on a keyboard/desk would make a good example activation system. We opted on using to fist-slamming method opposed to the head-desk method to prevent killing brain cells during testing. We borrowed a force sensitive resistor from DAT. I hooked it up to the Arduino and managed to get some nice readings off it. I taped it to the underside of the keyboard and noted the range of values it produced when I slammed my fist down on the keyboard. I successfully got the fist-slam on the keyboard to activate an LED.

The next step was to get the coffee machine to work. We initially were going to use a servo to hit the switch and manually activate it, but instead I opted on using my mains remote control. It's works by using radio frequency to transmit on/off signals to receivers that go between the mains socket and any mains-powered device. Initially I was planning on removing the buttons on the remote control's PCB, and replacing them with transistors or relays so I could directly control the signals with the Arduino. However due to the short timeframe of the project I instead mounted the servo onto the remote, and precisely calibrated with sellotape and precise degrees of movement to be able to hit two different 'on' buttons. Allowing us to control two mains powered devices.

Precisely calibrated servo-powered remote.


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