Wearable computers are rugged, portable computers that can be comfortably worn on the body and easily operated for maintenance applications. The recently developed process of Shape Deposition Manufacturing has created the opportunity to embed the electronics of wearable computers in a polymer composite substrate. As both a protective outer case and a conductive heat dissipating medium, the substrate satisfies two basic constraints of wearable computer design: ruggedness and cooling efficiency. One such application of embedded electronics is the VuMan3R, a wearable computer designed and manufactured at Carnegie Mellon University for aircraft maintenance. This paper combines finite element numerical simulations, physical experimentation, and analytical models to understand the thermal phenomena of embedded electronic design and to explore the thermal design space. Numerical models ascertain the effect of heat spreaders and polymer composite substrates on the thermal performance, while physical experimentation of an embedded electronic artifact ensures the accuracy of the numerical simulations and the practicality of the thermal design. Analytical models using thermal resistance networks predict the heat flow paths within the embedded electronic artifact as well as the role of conductive fillers used in polymer composites. [S1043-7398(00)00102-X]
This paper describes the concurrent system design and thermal management of the 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 spectrum radio, and variable gain amplifier (VGA) head-mounted display. The semi-custom electronic design includes two electronic boards-a custom-designed system board and a 486-based processor board. The system board captures glue logic functions and provides support for two PCMCIA slots, a power management microcontroller, 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 concurrent 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 the 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 the heat spreader design on the maximum electronic component 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 with better agreement to the experimental measurements on the Navigator2.
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
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.