Clutch mode control logic

In a vehicle having a gear transmission including an input shaft driven through a friction clutch by an engine that is controlled by an accelerator pedal, and having a clutch actuation controller for actuating the friction clutch, wherein the friction clutch has engageable parts which initially touch and then progressively increase in torque transfer during actuation, the clutch actuation controller having automatic modes including touch point approach mode, creep mode, startup mode and lockup mode, and an auto mode off state;

• the method of controlling the engine speed during clutch closing comprising the steps of:
• measuring engine speed, transmission input speed, and pedal position and producing corresponding signals;
• initiating operation in the auto mode off state, wherein the clutch is disengaged;
• changing from the auto mode off state to the touch point approach mode when the pedal position is above a minimum;
• in touch point approach mode controlling the clutch to a touch point;
• determining the touch point when the engageable parts of the clutch initially touch;
• entering a creep mode when the touch point is attained and the pedal position signal is below a threshold;
• when in creep mode, generating a control signal equal to the pedal position signal;
• entering the startup mode when the clutch touch point is attained and the pedal position signal exceeds the threshold value;
• when in startup mode generating a control signal comprising a fixed percentage of pedal position signal;
• and
• controlling the engine speed in accordance with the control signal.