System-level thermal management and concurrent system design of a wearable multicomputer system

Abstract

This paper desaibes the concurrent system design and thermal management of t h e Navigator2 which is used as a computerized maintenance manual for aircraft inspection with speech recognition capabilities. The Navigator2 is a wearable computer that includes a novel dual architecture, spread spednun radio, and VGA head-mounted display. The semiastom electronic design includes two electronic boards -a custom-designed system board and a &based processor board. The system board captures glue logic fundions and provides support for two PCMUA slots, a power management microconkoller, memory backup batteries, and a power supply.The thermal design of the Navigator2 develops concurrently with the overall design in a series of stages.A framework of concruwnt thermal engineering consisting of three basic stages is used to maintain interdisciplinary interaction while satisfying thermal design goals. In the first stage of the thermal design, a cooling arrangement that meets the needs of other disciplines is proposed, and an enhanced-conduction thermal design with aluminum heat spreaders and active power-saving is explored. In the second stage, the thermal contact between heat spreaders and electronic components is optimized, and physical experimentation is performed with liquid heat sinks and conductive elastomers as thermal contact interfaces. In the third stage, numerical simulations are performed to ascertain the effectiveness of the thermal design, giving t h e thermal designer flexibility to change critical parameters and perform sensitivity analyses. A simplified computational model is used to investigate the performance of thermal interface devices and the effect of t h e heat spreader design c n the maximum electronic componenf temperatures. Although the simplified model proves adequate for thermal design purposes, a detailed geometrically-accurate computational model assesses the adequacy of the exposed heat spreader surface area and predicts temperature distributions w i t h better agreement to the experimental measurements m the Navigator2

Integrating Design Education, Research and Practice at Carnegie Mellon: A Multi‐disciplinary Course in Wearable Computers

“…• Electronics: electronic components, electronic interfacing, power supply • Industrial and Mechanical: ergonomics, housing, component placement, thermal management, mechanical fixtures, design for manufacture, design for assembly, design for repair, design for recycling • Software: operating systems and support software, user interface tools, libraries for position sensing and telecommunications, hardware drivers • Human-Computer Interaction (HCI): speech and user interface The class has successfully designed and built five generations of wearable, mobile computers: VuMan1, 22 VuMan2, 23 Navigator1, 24 VuMan3, 25 and Navigator2. 26 Each of these computers has been produced in small batch sizes (ranging from 3 to 30; see Figure 1) and delivered to the customer for use. We are currently designing a rugged, specialized wearable computer for field maintenance and a general purpose, modular mobile computer with speech recognition and global positioning capabilities.…”