The design of the EnviS mobile devices has taken into consideration the broad environments that they will be used within. As such, a simple, robust structure was chosen to encase the electronic components whilst also providing ease-of-access for sensor replacement, customisation or repair.
With a desire to operate in a variety of locations, the mobile devices feature affordance for modular end-caps that allow the devices to perform appropriately in different user scenarios. The prototype was equipped with separate flat, magnetic and carabineer hook end-caps to allow it to be placed on a tabletop, affixed to a metal surface, affixed to a backpack, belt-loop or any other suitable object. The minimal material allocation used in the end caps means they are cheap to manufacture in relation to the larger housing, allowing for some degree of agile development and reaction to user needs.
The prototype cases are 3D-Printed using stereolithographic (SLA) technology. The chosen material is an Accura® Xtreme Plastic that simulates the properties of the industrial thermoplastic ABS – a material common in many mass-produced injection moulded electronic housings from TV remotes and Lego blocks to automotive components and medical devices. This allows for a strong, functional prototype that can be tested faithful to its performance as a mass-produced device. Similarly, the 3D CAD files used to produce the housing do not rely on the “impossible-to-machine” abilities of 3D-printing, meaning that the form can be expressed in traditional manufacturing tooling suitable for a two-part mould; a more cost-effective option for large-volume productions.
Electronically, the prototypes use various Arduino microcontrollers, notably the Arduino Fio and the Arduino Yun for the mobile devices and base station, respectively. The Arduino boards make use of Atmel AVR chips (particularly the ATmega series), which allow for the software employed in the prototypes to be directly ported onto mass-produced PCB’s using the same chipsets and sensors at a fraction of the cost. The communication is carried out using XBee digital radios utilising the ZigBee specification which conforms to the international standard IEEE 802.15.4 and is common within the IoT community and early applications.
Nishant Sony, Mars Dela Pena, Abdelsalam Ahmed Saad, Bo Wu, Yury Petrov
(Technical Development and Software Engineering Team, School of Computer Science and Information Technology)
Anton Van Maanen, Daniel Kerris
(Product Development Team, Industrial Design Program, School of Architecture & Design)
Dr. Flora Salim