400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-5760 Web: www.sae.orgSAE TECHNICAL PAPER SERIES 2004-01-0836 A Far Infrared Thermal Imager for Occupant Size and Position Sensing Brian Johnson First Technology, UK Tej Kaushal Alec Williams QinetiQ, UK Reprinted From: Air Ba gs and Belt Restraints (SP-1876) 2004 SAE World Congress Detroit, Michigan March 8-11, 2004Downloaded from SAE International by Univ of California Berkeley, Saturday, August 04, 2018All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise,without the prior written permission of SAE. For permission and licensing requests contact: SAE Permissions 400 Commonwealth DriveWarrendale, PA 15096-0001-USAEmail: permissions@sae.orgFax: 724-772-4891Tel: 724-772-4028 For multiple print copies contact: SAE Customer ServiceTel: 877-606-7323 (inside USA and Canada)Tel: 724-776-4970 (outside USA)Fax: 724-776-1615Email: Customer Service@sae.org ISBN 0-7680-1319-4Copyright © 2004 SAE International Positions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE. The author is solely responsible for the content of the paper. A process is available by which discussions will be printed with the pap er if it is publishe d in SAE Transactions. Persons wishing to submit papers to be considered for presentation or publication by SAE should send themanuscript or a 300 word abstract of a proposed manuscript to: Secretary, Engineering Meetings Board, SAE. Printed in USADownloaded from SAE International by Univ of California Berkeley, Saturday, August 04, 2018 2004-01-0836 A Far Infrared Thermal Imager for Occupant Size and Position Sensing Brian Johnson First Technology, UK Tej Kaushal Alec Williams QinetiQ, UK Copyright © 2004 SAE International Abstract This paper describes the work being undertaken jointly by QinetiQ and First Technology to develop a low cost thermal sensor to help vehicle manufacturers meet the smart airbag regulations being introduced by NHTSA. The sensor is based on technology developed by QinetiQ and licensed to First Technology. It is a resistance bolometer that is sensitive to energy in the 8µm - 14µm waveband. An image is constructed and then image processing is performed to classify the occupants and determine their position. This information will then be available to the airbag system to assist in the deployment decision. This paper outlines the requirements for the sensor and trial work to address the feasibility of using a thermal sensor in the automotive cabin environment. In particular, it addresses the effects of background temperature, occupant clothing, contamination and obscuration of the lens of the sensor. Briefly, the key advantages of this thermal sensor are: passive sensing, providing an image regardless of illumination conditions without shadows or modulated light though the windshield, and low resolution requirements resulting in reduced quantities of data on which image processing must be performed. Additional functionality has been considered for the sensor, principally as an input to the HVAC system or as an intruder detector. 1 Introduction The proposed NHTSA smart airbag rules state that the safety restraint system adjusts its operation depending upon the classification and position of the occupants to reduce the possibility of injury being caused by the airbag. To meet this requirement, QinetiQ and First Technology are developing a sensor system based on a low cost thermal sensor. The proposed sensor is extremely robust and consumes little electrical power. Historically, thermal imaging applications have been constrained by the high cost of specialized sensing arrays developed for military purposes. QinetiQ has developed and patente