Launch control of a hybrid electric vehicle

A method for controlling the launch of a vehicle having a powertrain that includes a first power path for driving a first wheel set and including an engine, a transmission having an input driveably connected to a crankshaft of the engine, a current gear, an input clutch associated with the current gear and an output connected to first wheel set, and a second power path including an electric machine for driving a second wheel set, comprising the steps of:

• (A) using an operator demand for a desired wheel torque to determine a desired wheel torque at the first wheel set and a desired wheel torque at the second wheel set;
• (B) using the desired magnitude of wheel torque to be produced at the first wheel set to determine a magnitude of desired crankshaft torque;
• (C) producing a predetermined magnitude of torque capacity of the input clutch;
• (D) determining a crankshaft speed error;
• (E) determining a change in magnitude of torque at the crankshaft that will reduce the crankshaft speed error;
• (F) operating the engine to produce a desired engine torque, whose magnitude is determined from the change in magnitude of torque at the crankshaft and the magnitude of desired crankshaft torque;
• and
• (G) operating the electric machine to produce the desired magnitude of torque at the second wheel set.

A system for controlling a vehicle launch condition comprising:

• the first wheel set driveably connected to an engine that includes a crankshaft;
• a transmission including an input driveably connected to the crankshaft and an output, the transmission being able to operate in a current gear;
• an input clutch for alternately closing and opening a drive connection between the crankshaft and transmission input;
• and
• an electric machine driveably connected to the second wheel set;
• a controller configured to determine a desired magnitude of wheel torque to be produced at the first wheel set and the second wheel set, determine a magnitude of crankshaft torque, produce a predetermined magnitude of torque capacity of the input clutch, determine a crankshaft speed error, determine a change in magnitude of torque at the crankshaft that will reduce the crankshaft speed error, operate the engine to produce a desired engine torque, whose magnitude is determined from the change in magnitude of torque at the crankshaft and the magnitude of desired crankshaft torque, and operating the electric machine to produce the desired magnitude of torque at the second wheel set.