Thermal Band

The aim of the project was to create an interface which provided feedback through a more natural meanes without requiring direct interaction from the user. The hope was to allow the user to receive feedback without forcing them to actively move away from their current task. The interface therefore uses heat to express various amounts of information adjusting the temperate of the surface to either appear physically hot or cold relative to your body temperature. This interface is part of a final year project looking at creating a bluetooth communication infrastructure for context aware application development. The intention is that the object can be worn or carried in the users pocket and will respond as it moves within the environment giving subtle feedback in the form of temperature change. The initial use of this device will be to provide feedback relating to the position of the user as they navigate an environment. As GPS is unreliable indoors the location of the device is referenced by the presence of the pre determined bluetooth infrastructure and depending on the requested route will become warmer as they reach their destination and likewise cool as they move off course.

As the device is controlled by the users mobile phone it can be used to pervay other information such as reminding the user 5 minutes before the start of a lecture or when they are within a certain environment such as a library. An example appliction uses the band to provide warning to the wearer as they move into more dangerous locations. This helps the wearer understand how dangerous various areas/districts of a city are and allows you to adjust your route as you move through unfamiliar teritory. This is acheived through the use of the UK police statistics API creating a map indicating the relative crime levels of each area. As the wearer then physically moves around as they enter an area with a higher or lower crime level to their previous location the band alterts them by altering the temperature acoridngly. An example of the various crime levels can be seen in the illistration opposite dipicting the city of Cardiff in wales.

The purpose of the project is therefore to help disseminate information to the user in a non traditional form without the need for them to actively seek and interpret the data. By using heat to communicate various relationships the hope is to use the pre existing associations to help reduce the need for rote learning of the various interactions. For example traditionally hot signifies getting closer to a goal like in the game of hide and seek as you reach the target and cold when you move off course. This relationship can be therefore transferred into the physical environment allowing navigation systems using the same principle.

The system is based around the AirCable micro controller and bluetooth module allowing rapid prototyping for the system. The micro controller when powered undertakes a bluetooth device discovery looking for available hardware before further checking each service discovery record for a specific service facilitating communication. The interface then connects and simple serial data can be transferred which in turn either warms or cools the surface of the device for a short period of time. The heating and cooling effect is achieved through the use of a Peltier plate which utilises the thermoelectric effect to ensure that one surface of the module becomes warm and the other cools. In this project as the device needs to be able to both cool and heat the object two plates are utilised which are positioned next each other. The micro controller then switches the voltage between each plate making the surface appear to the user either warm or cool. Due to the voltage requirements of the plate and the size constraint of the whole device the battery life is heavily effected giving the device an extremely short working time for this prototype. For the current application the interface is driven by the wearers mobile phone which connects to the device and sends appropriate serial data effecting the temperature. This allows the mobile device to utilise its in built GPS unit for route tracking outside of buildings. For internal use the mobile device scans for bluetooth enabled devices and checks discovered IDs against a known list, through this the movement of the user is determined and changes in the interface are made.

More Info

Aircable SMD, UK Crime Mapping, Thermoelectric Effect