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In general, the most essential role of a transmission is to transmit the driving power of the power source to the wheel as much as possible without loss, and in this process, the operating point of the power device is controlled by shift schedule so that the driving efficiency can be maximized through appropriate gear shifting. Regardless of this driving efficiency of the power source, it often occurs that gear shifting can be helpful to the driving situation in the viewpoint of the driver's convenience. It refers to a case in which a rapid deceleration or acceleration must be prepared in advance depending on a specific driving event, such as winding road, downhill, speed bump or entering a highway and so on. In the case of an automatic transmission, the function of shifting to maximize the driving efficiency of the power source can be achieved according to the shift scheduling that has already been set to an optimum value. The automatic transmission, however, is likely to be more disadvantageous than a manual transmission in which the driver directly operates the gear position while observing the outside situation according to the approximate road shape and traffic flow. It is possible to realize an optimized predictive control system that enables early gear shifting of transmission in preparation for upcoming driving situations by connecting the transmission with the connectivity devices in the vehicle that provides various information of the road geometry and traffic conditions in front of the vehicle. In this study, we would like to introduce a new technologies of multiple predictive gear shifting control system and its application effect on the real road driving, that predicts at once the various driving situations expected to occur in the future and performs appropriate transmission gear before the situation by using electronic horizon including 3-dimentional map data and signals from front radar and camera equipped in the vehicle. The technology consists of following three steps: 'Situation Decoding Step' that converts the various raw signals from electronic horizon devices into a comprehensive driving situation that can be understandable to the transmission control unit, 'Speed Prediction Step' that determines the vehicle speed profile required for the upcoming driving situation, and 'Powertrain Control Step' that controls the most proper transmission gear and engine torque. The multiple predictive gear shifting system of automatic transmission proposed in this study was applied to mass production in Hyundai-Kia vehicles, and contributed not only to drivability, safety, and vehicle durability, but to improving fuel efficiency in real road driving.
Mr. Byeong Wook Jeon, Hyundai Motor Company, REPUBLIC OF KOREA Mr. Min Jae Chai, Hyundai Motor Company, REPUBLIC OF KOREA Mr. Kwang Hee Park, Hyundai Motor Company, REPUBLIC OF KOREA