Personal Environments™ is a Johnson Controls, Inc. system for the control of indoor office environments. In this system, four SMA coiled extension springs interact to control the position of two dampers. Two opposing SMA springs connected to one damper control the percentage of primary conditioned air entering the system, and two opposing SMA springs connected to the second damper control the percentage of room air reentering the system.
The interactive operation of the SMA springs is discussed and a model is presented on the interactive response of the SMA springs. The SMA spring transformation temperatures, force - strain relationship, and the experimentally measured interactive response to temperature are presented and discussed.