Automatic transmission bypass clutch slip control using nonlinear nverse dynamics

A system for controlling a torque converter bypass clutch operating in an automatic transmission adapted for connection to an engine controlled by a variable position throttle, comprising:

• a torque converter having an impeller adapted for connection to the engine, a turbine adapted for hydrokinetic connection to the impeller, and a clutch whose full engagement mechanically connects the impeller and turbine and whose full release mechanically disconnects the impeller and turbine, partial engagement of the clutch permitting a difference in speed or slip between the impeller and turbine;
• a source of hydraulic pressure;
• an electrical solenoid-operated valve opening and closing communication between the pressure source and clutch, for producing a variable magnitude clutch pressure in the clutch in response to a duty cycle applied to the solenoid;
• means for producing signals representing impeller speed, turbine speed, clutch pressure, and throttle position;
• an engine model responsive to the signals representing engine manifold conditions and engine speed for producing a signal representing predicted engine torque;
• a powertrain model responsive to turbine speed, impeller speed, and predicted engine torque for producing a signal representing net engine torque;
• an inverse clutch model responsive to said signal representing net engine torque for producing a signal representing desired clutch pressure corresponding to net engine torque;
• a nonlinear inverse model including
• effective delay means for delaying, for a period representing delay in response of said system to a command for change in engine torque, solenoid delays and computational delays, production of a signal representing the second derivative of current bypass clutch pressure with respect to time,
• engine delay means for delaying, for a period representing delay in response of the engine to a command for change in engine torque, production of a signal representing an error compensation signal, and
• means for producing a first duty cycle comprising the sum of the signals produced by the effective delay module and engine delay module;
• and
• a solenoid inverse model responsive to said first duty cycle signal for producing a second duty cycle having a nonlinear relation to the first duty cycle.