Development of the brake assist system.doc

980601SAE TECHNICAL PAPER SERIESDevelopment of the Brake Assist SystemHiroaki Yoshida, Tatsuo Sugitani, Masashi Ohta, Jiro Kizaki, Atsushi Yamamotoz and Koji Shirai Toyota Motor CorporationReprinted From: ABS/Brake/VDC Technology (SP-1339)The Engineering Society For Advancing Mobility Land Sea Air and Space© INTERNATIONALInternational Congress and Exposition Detroit, Michigan February 23-26,1998400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-5760 The appearanee of this ISSN code at the bottom of this page indicates SAE's consent that copies of the paper may be made for personal or internal use of specific dients. This consent is given on the condition, however, that the copier pay a $7.00 per article copy fee through the Copyright Clearance Center, Inc. Operations Center, 222 Rosewood Drive, Danvers, MA 01923 for copying beyond that permitted by Sec- tions 107 or 108 of the U.S. Copyright Law. This consent does not extend to other kinds of copying such as copying for general distribution, for advertising or promotional purposes, for creating new collective works, or for resale・SAE routinely stocks printed papers for a period of three years following date of publication. Direct your orders to SAE Customer Sales and Satisfaction Department.Quantity reprint rates can be obtained from the Customer Sales and Satisfaction Department.To request permission to reprint a technical paper or permission to use copyrighted SAE publications in other works, con tact the SAE Publicatio ns Group ・GLOBAL MOBIUTY DATABASEAll SAE papers, standards, and selected books are abstracted and Indexed in the Global Mobility DatabaseNo part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher.ISSN 0148-7191Copyright 1998 Society of Automotive Engineers. Inc.Positions and opinions advanced in this paper are those of the aulhor(s) and not necessarily those of SAE. The author is solely responsibie for the content of the paper. A process is available by which discussions will be printed with the paper if it is published in SAE Transactions. For permission to publish this paper in full or in part, contact the SAE Publications Group.Persons wishing to submit papers to be considered for presentation or publication through SAE should send the manuscript or a 300 word abstract of a proposed manuscript to: Secretary. Engineering Meetings Board. SAE・Printed in USA980601Development of the Brake Assist SystemHiroaki Yoshida, Tatsuo Sugitani, Masashi Ohta, Jiro Kizaki, Atsushi Yamamoto and Koji Shirai Toyota Motor CorpcrationCopyright © 1998 Society of Automotive Engineers, Inc.#ABSTRACTWe investigated and analyzed the average vehicledrivers braki ng behavior in panic situati ons by con ducting vehicle tests that duplicated real world conditions that would require emergency braking performanee. From our investigation, we have noticed that when panic braking is recognized, supplying additional braking power is effective for active safety. The Brake Assist System, which supplies full constant braking force when panic braking is recognized, is effective for drivers who cannot apply enough braking effort. However, in some case, such a system makes more experieneed drivers uncomfortable because the deceleration caused by this full constant braking force might be different from their intentions. Considering these issues, we have developed the Brake Assist System that increases its controllability while reducing its discomfort. The TOYOTA RAUM has been available with the Brake Assist System since May 1997.INTRODUCTIONAnalyses by means of simulations (1)(2) and experiments (3)(4)(5) using jumping-out obstacles have been conducted on the drivers' behaviors in panic situations. Based on these results, it has been reported that ordi- nary drivers fail to make a full brake pedal effort in such situations. Brake assist (BA) systems (6)(7) that supple- ment the braking force upon recog nition of emergency situation have been proposed, and a system that applies a given maximum braking force upon detection of panic braking was developed (7).Although such a system is effective for inexperieneed drivers who may fail to reach full brake pedal effort in such situations, the application of braking force different from the driver's intent on may be uncomfortable for skilled drivers.For this reason, a Brake Assist System with a proper control performanee that would not make skilled drivers uncomfortable has been developed.Braking operations normally made by ordinary drivers will be discussed first i n the followi ng, by reproducing urge nt situations close to reality requiring emergency avoidanee measures. Then the Brake Assist System we have developed according to the results of investigation and analysis will be described.DRIVERS' BRAKING OPERATI。