Closed loop launch and creep control for automatic clutch

In a combination including a source of rotary motive power, a throttle for control of torque generated by the source of motive power, a transmission, a friction clutch for selectively coupling the source of rotary motive power with the transmission and having an input shaft connected to the source of motive power and an output shaft connected to the transmission, and at least one inertially-loaded traction wheel connected via the transmission to the output shaft of the friction clutch having a torsional compliance exhibiting an oscillatory response to torque inputs, an automatic controller for the friction clutch comprising:

• a throttle sensor connected to the throttle for generating a throttle signal indicative of throttle position;
• an engine speed sensor connected to the source of motive power for generating an engine speed signal corresponding to rotational speed of the source of motive power;
• a reference speed generator connected to said throttle sensor and said engine speed sensor, said reference speed generator including
• a launch/creep selector connected to said throttle sensor for selecting either a launch mode or a creep mode based upon the magnitude of said throttle signal,
• a creep speed reference generator connected to said engine speed sensor and said throttle sensor for generating a creep speed reference signal corresponding to said engine speed signal and said throttle signal, and
• a mode selection switch connected to said engine speed sensor, said launch/creep selector and said creep speed reference generator for selectively generating a reference speed signal corresponding said engine speed signal if said launch mode is selected and corresponding to said creep speed reference signal if said creep mode is selected;
• a transmission input speed sensor connected to an output shaft of the friction clutch for generating a transmission input speed signal corresponding to rotational speed of the output shaft of the friction clutch;
• a clutch actuator connected to the friction clutch for controlling engagement of the friction clutch from disengaged to fully engaged according to a clutch engagement signal;
• and
• a controller connected to said engine speed sensor, said transmission input speed sensor and said clutch actuator including
• an algebraic summer connected to said reference speed generator and said transmission input speed sensor forming an algebraic sum signal corresponding to the difference between (1) said reference speed signal and (2) said transmission input speed signal, and
• a compensator connected to said algebraic summer for generating a clutch engagement signal from said algebraic sum signal for supply to said clutch actuator for engaging the friction clutch in a manner causing said transmission input speed signal to asymptotically approach said reference speed signal.

In a combination including a source of rotary motive power, a transmission, a friction clutch for selectively coupling the source of rotary motive power with the transmission and having an input shaft connected to the source of motive power and an output shaft, the transmission having an input shaft connected to the output shaft of the friction clutch and providing a selectable gear ratio to an output shaft, and at least one inertially-loaded traction wheel connected to the output shaft of the transmission having a torsional compliance exhibiting an oscillatory response to torque inputs, an automatic controller for the friction clutch comprising:

• a transmission shift controller connected to the transmission for controlling the gear ratio selected by the transmission;
• an engine speed sensor connected to the source of motive power for generating an engine speed signal corresponding to rotational speed of the source of motive power;
• a reference speed generator connected to said engine speed sensor for generating a reference speed signal;
• a transmission input speed sensor connected to the input shaft of the transmission for generating a transmission input speed signal corresponding to rotational speed of the output shaft of the friction clutch;
• a clutch actuator connected to the friction clutch for controlling engagement of the friction clutch from disengaged to fully engaged according to a clutch engagement signal;
• and
• a controller connected to said transmission shift controller, said reference speed generator, said transmission input speed sensor, and said clutch actuator, said controller implemented via discrete difference equations executed by a microcontroller and including
• an algebraic summer connected to said reference speed generator and said transmission input speed sensor forming an algebraic sum signal corresponding to the difference between (1) said reference speed signal and (2) said transmission input speed signal,
• a coefficient memory for storing a plurality of sets of coefficients, one set of coefficients corresponding to each selectable gear ratio of the transmission, and
• a compensator connected to said algebraic summer and said coefficient memory for generating a clutch engagement signal from said algebraic sum signal for supply to said clutch actuator for engaging the friction clutch in a manner causing said transmission input speed signal to asymptotically approach said reference speed signal, said compensator implemented in discrete difference equations employing a set of coefficients recalled from said coefficient memory corresponding to the gear ratio of the transmission.