ea m The EngineeringResource ForAdvancing Mobility 400 COMMONWEALTH DRIVE WARRENDALE, PA 15096 820394 Microcomputer Controlled Automatic Transmission Alan L. Miller Borg-Warner Research Center Des Plaines, IL Reprinted from P-104— "Electronic Engine Management and Driveline Controls" International Congress & Exposition Detroit, Michigan February 22-26, 1982Downloaded from SAE International by Imperial College London, Sunday, September 09, 2018ISSN 0148-7191 Copyright 1982 Society of Automotive Engineers, Inc.Downloaded from SAE International by Imperial College London, Sunday, September 09, 2018820394 Microcomputer Controlled Automatic Transmission Alan L. Miller Borg-Warner Research Center Des Plaines, IL ABSTRACT This paper will discuss the concept, design and development progress of Borg-Warner's microcomputer controlled automatic transmission. It was ascertained that an electronic transmission control system capable of high performance and cost effectiveness must combine both shift point and shift quality as an integrated control. Flexible shift point schedules were programed as any given function of throttle position and transmission output shaft speed. Shift quality control includes both upshift and downshift ratio changes. This is achieved using a unique torque transducer positioned on the output shaft of the transmission. The shift quality strategies utilize this transducer in open loop algorithms and a high response closed loop torque control system. THE LONG RANGE MOTIVATION for the design, development and manufacture of an electronically controlled automatic transmission is the ability of the transmission to communicate with other electronic control systems in the vehicle. The engine management and control function, integrated with the transmission, represents a total driveline control system. There is no doubt that there are many advantages to an electronically controlled automatic transmission on its own merit, as an independent system, but the future of overall driveline control will require this type of transmission. Borg-Warner's initial concept included only electronic control of shift point computation. The shift quality control retained its original hydromechanical configuration, one way clutches, accumulators and orifices. This concept was a serial add-on electronic package and did not optimize the transmission control for minimum hardware or maximum performance. It was ascertained that an electronic transmission control system capable of high performance and cost effectiveness must combine both shift point and shift quality as an integrated control.The system objectives for an electronic integrated control package are: The system shall interface with other vehicle control systems, such as engine control, and could be part of a centralized computer system. The system shall have the flexibility to allow for easy modification of transmission shift point and shift quality control characteristics. Simplification of hydraulic components. This would enable an increase in the number of speed ratios to five or more. The system shall provide consistent performance under all operating conditions, using less critical transmission component specifications. The system objectives provided the design criteria and produced a basic concept with the following features: The shift point has independent upshift and downshift functions. Multiple shift schedules may be programmed for different driving styles. Shift quality is a term that defines the degree of driveline disturbance resulting from a gear ratio change. Our analysis indicated that by observing and controlling the transmission output shaft torque, we would obtain good shift quality with respect to energy, timing and rotation of interchanging friction elements. A special non-contacting torque transducer was developed by Borg-Warner for placement on the output shaft of the transmission. This provided the primary information for all ratio changes. Throttle position and e