A method is provided for calibrating a control algorithm of a clutch control unit of a vehicle. The method includes requesting, clutch disengagement or engagement, monitoring clutch actuator position, determining a time interval that starts with the clutch disengagement or engagement request and ends when the clutch actuator has reached a predetermined position, and calibrating an estimated time interval of the control algorithm starting with clutch disengagement or engagement request and ending when the clutch actuator has reached a predetermined position based on the determined time interval. A computer program for implementing the method, as well as a vehicle comprising a clutch control unit calibrated according to the method, are also provided.

A method of preventing a vehicle clutch from sticking includes a wear compensation actuation step of actuating a wear compensation device in conjunction with engagement actuation of a clutch actuator after an ignition is turned off when an actuation condition of the wear compensation device is satisfied, and a clutch control step of controlling a clutch position so that the clutch position returns to a disengaged state of the clutch actuator by reactuating the wear compensation device, when a clutch position based on an amount of variation in an actuation length of the actuation rod fails to return to the disengaged state of the clutch actuator during returning of the engaged clutch actuator.

A method and an apparatus for learning linearity error of a hydraulic pressure sensor for a hydraulic clutch are disclosed. An apparatus for learning linearity error of a hydraulic pressure sensor for a hydraulic clutch may include: a gear stage sensor detecting a gear stage that is currently engaged; a controller executed by a predetermined program to learn the linearity error of the hydraulic pressure sensor based on signals of the gear stage sensor and the hydraulic pressure sensor; and a solenoid valve applying hydraulic pressure for learning the linearity error of the hydraulic pressure sensor to the hydraulic clutch based on a learning command of the controller.

A method may be provided for correcting a raw signal supplied by a pressure sensor in an all wheel drive system having a hydraulic pump and a hydraulic fluid. The method may include measuring the raw signal supplied by the pressure sensor, determining when the all wheel drive system is in a state where the hydraulic fluid is at a known pressure determined independently from the pressure sensor, determining a new zero-point offset by comparing the raw signal to a voltage value associated with the known pressure, and creating a corrected voltage signal by adjusting the raw signal based on the new zero-point offset. This corrected voltage signal may be converted into a pressure reading for controlling the all wheel drive system.

A method of calibrating a hydraulically operated clutch in a continuously variable transmission of a vehicle, includes steps of filling the clutch as if for a shift, using a control signal value for achieving a test pressure, and determining a resulting change in a pressure condition in a hydrostatic power unit of the transmission. If the change indicates initial engagement, then a value representative of the signal value used is recorded. If greater than initial engagement is indicated, or the vehicle moved, then the clutch is emptied and tested using a lower test pressure. If initial engagement is not indicated, the clutch is emptied and refilled to a greater test pressure. An exemplary pressure condition is a difference in pressure in lines between a pump and motor of the power unit. During the calibration, the vehicle can be held stationary with a parking brake or the like.

A clutch control system for a vehicle includes: a reset module configured to selectively start a reset operation of a clutch actuator of a clutch that engages and disengages an electric propulsion motor to and from a gearset; a target position module configured to perform the reset operation by setting a target position of the clutch actuator to follow a predetermined position profile for the reset operation, the reset operation including (a) opening an orifice between a hydraulic fluid reservoir and an pressure chamber of the clutch actuator (b) closing the orifice after the opening; and a clutch control module configured to actuate the clutch actuator based on the target position thereby performing the reset operation.

A method of preventing a vehicle clutch from sticking includes a wear compensation actuation step of actuating a wear compensation device in conjunction with engagement actuation of a clutch actuator after an ignition is turned off when an actuation condition of the wear compensation device is satisfied, and a clutch control step of controlling a clutch position so that the clutch position returns to a disengaged state of the clutch actuator by reactuating the wear compensation device, when a clutch position based on an amount of variation in an actuation length of the actuation rod fails to return to the disengaged state of the clutch actuator during returning of the engaged clutch actuator.

A method for learning a torque-stroke (T-S) curve of an electric motor controlled dry clutch system is disclosed. The method includes calculating a position change value A for allowing a position change point P3 corresponding to an arbitrary torque y3 on a previous T-S curve C1 to follow-up and be moved to an expectation T-S curve C3, by a control unit, calculating a probability Pr_X3 to allow the position change value A to consider various environmental factors of a clutch within a valid range, and multiplying the probability Pr_X3 to the position change value A to calculate a final position change value A, by the control unit, and calculating a new point P3 by applying the final position change value A to the position change point P3 of the previous T-S curve C1, and generating a final T-S curve connecting the new point P3 and a touch point to learn, by the control unit.

A method and an apparatus for learning linearity error of a hydraulic pressure sensor for a hydraulic clutch are disclosed. An apparatus for learning linearity error of a hydraulic pressure sensor for a hydraulic clutch may include: a gear stage sensor detecting a gear stage that is currently engaged; a controller executed by a predetermined program to learn the linearity error of the hydraulic pressure sensor based on signals of the gear stage sensor and the hydraulic pressure sensor; and a solenoid valve applying hydraulic pressure for learning the linearity error of the hydraulic pressure sensor to the hydraulic clutch based on a learning command of the controller.

A method may be provided for correcting a raw signal supplied by a pressure sensor in an all wheel drive system having a hydraulic pump and a hydraulic fluid. The method may include measuring the raw signal supplied by the pressure sensor, determining when the all wheel drive system is in a state where the hydraulic fluid is at a known pressure determined independently from the pressure sensor, determining a new zero-point offset by comparing the raw signal to a voltage value associated with the known pressure, and creating a corrected voltage signal by adjusting the raw signal based on the new zero-point offset. This corrected voltage signal may be converted into a pressure reading for controlling the all wheel drive system.