Abstract A new shift control system using a model-based control method for stepped automatic transmissions. Using a gear train numerical formula model, the model-based shift control system is constructed using minimum calibration parameters with feedforward and feedback controllers. It also adopts control target values for the input shaft revolution and output shaft torque, thus enabling precise control that provides the most suitable shift feeling in various driving situations and for various vehicle characteristics. Furthermore, the model-based shift control system improves robustness in terms of disturbance elements such as production tolerance, time degradation, and use environment. Toyota has adopted this model-based shift control system in its UA80/UB80 8-speed automatic transmissions for front-wheel-drive vehicles and its AGA0 10-speed automatic transmission for rear-wheel-drive vehicles. This paper describes the details of this model-based shift control system. 1. Introduction The development of shift control system for stepped automatic transmissions must not only lead to improvements in fuel efficiency and drivability, but also respond to diversifying needs such as potential system combinations (e.g., driving support system or power train system) or deployment to a broader range of destinations. Higher performance control systems and more advanced coordination between systems are being developed to address such needs. Until now, a large number of correction terms addressing such needs were used to make shift control algorithms both large and complex. Moreover, with fuel efficiency and dynamic performance improvements bringing about multi-speed automatic transmissions, the frequency of shifting in response to driver operations has increased, and a significant amount of time has to be allocated to logic design and validation. Alternatively, it could become necessary to impose partial limits on shifting performance and sacrifice shifting response. Similarly, differences in the transmission hardware configuration, such as different number of steps or constituent components, or modifications to hardware specifications or engine characteristics, require a considerable amount of labor and time to rewrite the software, and redo the calibration and validation. The resulting need for a shift control algorithm that could be adapted with a minimum of modifications and validation led to building an algorithm incorporating a model-based control method. 2. Design Concept for the New Shift Control System The design of the new shift control algorithm was guided by the four concepts below. 2-1. Highly Precise Controllability Design shift control that features a high degree of accuracy in terms of shift transient characteristics. *Driving force, shifting time or other shifting characteristics. 2-2. Improvement of Robustness Design shift control that accurately reproduces smooth and high- response shifting relative to various disturbances such as manufacturing variations, use environment, and driver operations. 2-3. Improvement of Flexibility in the Design of Shift Transient Characteristics Enable unrestricted design freedom for shift transient characteristics adapted to the vehicle concept and the deployment destinations, and design shift control that achieves them with a high degree of accuracy.Development of New Shift Control System using a Model-based Control Method for Toyota Stepped Automatic Transmissions2017-01-1632 Published 03/28/2017 Norihiro Tsukamoto, Tomohiro Chimbe, Tomohiro Asami, Keisuke Ota, and Seiji Masunaga Toyota Motor Corporation CITATION: Tsukamoto, N., Chimbe, T., Asami, T., Ota, K. et al., "Development of New Shift Control System using a Model-based Control Method for Toyota Stepped Automatic Transmissions," SAE Technical Paper 2017-01-1632, 2017, doi:10.4271/2017-01-1632. Copyright © 2017 SAE InternationalDownloaded from SAE International by Univ of Nottingham - Kings Meadow C