Modeling, Simulation, and Control Implementation for a Split-Torque, Geared Neutral, Infinitely Variable Transmission
Split-torque, geared-neutral transmissions have been shown to improve vehicle performance over a conventional continuously variable transmission. Although control of these transmissions has presented significant problems in the past, we have been able to achieve good driveability and fuel economy through the use of an integrated engine/transmission control philosophy. Development of the transmission/engine control strategies are based on detailed dynamic models and computer simulations of the driveline. In developing the control laws, specific attention has been given to providing characteristics similar to that of a conventional automatic transmission, such as creep and hill-holding capabilities. Test results show adequate transmission response with high initial jerk if demanded, excellent stability at the geared-neutral point, and smooth transitions through the synchronous point as well as in all other driving conditions.