ABSTRACT This paper presents a newly developed integrated powertrain control system. The system coordinates the controls between engine and transmission to optimize powertrain operation for drive quality and fuel economy. This new control system uses the desired engine power as the common load variable for both engine and transmission control instead of throttle as is used in conventional powertrain controls. The main advantages to this control system are improved fuel economy and drive quality. Other advantages and a brief description of the control system will be described in more detail in the following discussion. INTRODUCTION From a driver's perspective, powertrain control in an automatic transmission equipped vehicle involves two main inputs: the gear range selector and the accelerator pedal. In traditional powertrain control systems, the throttle controller maps accelerator pedal position to an engine throttle position, and the transmission controller then selects the appropriate gear based on the throttle position, vehicle speed, and range selection. The traditional throttle-based powertrain control system has limitations such as: • With the incorporation of engine technologies such as Active Fuel Management, variable valve timing, and homogenous charge compression ignition; throttle is no longer a good indicator of engine performance. • Throttle is not a good indicator of powertrain performance in vehicles with more than one power source, i.e. hybrid. • Calibration for drive quality and fuel economy is not independent. This limits the ability to develop a calibration that is optimal for both. A lot of work has been previously done on the subject of integrated powertrain control ( 1,2,3,4,5) in order to improve on some of the limitations of traditional powertrain controls. The main topics of integrated powertrain control include: • Interpretation of driver's pedal input signal: Should it be interpreted as a demand for throttle, torque, or power? • Engine control: Should it be throttle based, engine torque based, or engine power based? • Transmission shift map: Should it be throttle based, torque based, or power based? • Clutch-to-clutch shift control: What is the best method of control in an integrated powertrain control system? Today, most passenger vehicles with a spark ignited internal combustion engine use an electronically controlled throttle. An electronically controlled throttle system provides additional flexibility and allows for the possibility of controlling the engine and transmission in an integrated manner to optimize control for reduced fuel consumption and improved drive quality. In order to take advantage of the additional flexibility of electronic throttle control and to overcome the limitations of a throttle-based control system, a power-based integrated powertrain control system has been developed. This power- based integrated powertrain control system includes the following control algorithms: • a power-based driver pedal input interpreter, • an engine torque command generator, • an engine torque control system, • a power-based transmission gear selection algorithm, Integrated Powertrain Control2010-01-0368 Published 04/12/2010 Shushan Bai, Daniel Brennan, Don Dusenberry, Tim Tao and Zhen Zhang GM Powertrain Copyright © 2010 SAE InternationalDownloaded from SAE International by Univ of Nottingham - Kings Meadow Campus, Monday, September 10, 2018• and a constant output torque clutch-to-clutch up-shift control algorithm The following discussion will first describe the overall control architecture of the system and then discuss in more detail the power-based transmission gear selection and the constant output torque clutch-to-clutch up-shift control. DISCUSSION OVERALL CONTROL ARCHITECTURE The overall architecture of the power-based integrated powertrain control system is shown in Figure 1. The system includes Pedal Input Interpreter, Engine Torque Command Generator, Engine Torque Control System