Abstract: A transmission control system of a vehicle includes an estimated acceleration module and a pressure control module. The estimated acceleration module determines an estimated longitudinal acceleration of the vehicle based on a force at axles of the vehicle corresponding to engine torque, a braking force imposed by mechanical brakes of the vehicle, an aerodynamic drag force of the vehicle, and a road load force imposed on the vehicle by contact between tires of the vehicle and a road surface. The pressure control module, when a measured longitudinal acceleration of the vehicle is negative and the estimated longitudinal acceleration is greater than the measured longitudinal acceleration of the vehicle, adjusts transmission fluid pressure applied to one or more clutches of the transmission and shifts the transmission to neutral.

Abstract: A method for monitoring a fixed-gear transmission includes deriving a node speed relationship for each of the planetary gear sets based upon a center distance and a gear ratio and determining equivalent speed parameters for nodes of the planetary gear sets based upon a transmission input speed state, an intermediate node speed state and a transmission output speed state. A clutch slip speed relationship is determined for each of the clutches based upon the node speed relationships for the planetary gear sets and the equivalent speed parameters for nodes of the planetary gear sets. Rotational speed sensors monitor the input transmission speed, the intermediate node speed and the transmission output speed. A clutch slip speed for each of the clutches is determined based upon the respective clutch slip speed relationship and the monitored input transmission speed, the monitored intermediate node speed and the monitored transmission output speed.

Abstract: A transmission control system of a vehicle includes an estimated acceleration module and a pressure control module. The estimated acceleration module determines an estimated longitudinal acceleration of the vehicle based on a force at axles of the vehicle corresponding to engine torque, a braking force imposed by mechanical brakes of the vehicle, an aerodynamic drag force of the vehicle, and a road load force imposed on the vehicle by contact between tires of the vehicle and a road surface. The pressure control module, when a measured longitudinal acceleration of the vehicle is negative and the estimated longitudinal acceleration is greater than the measured longitudinal acceleration of the vehicle, adjusts transmission fluid pressure applied to one or more clutches of the transmission and shifts the transmission to neutral.

Abstract: A method for monitoring a fixed-gear transmission includes deriving a node speed relationship for each of the planetary gear sets based upon a center distance and a gear ratio and determining equivalent speed parameters for nodes of the planetary gear sets based upon a transmission input speed state, an intermediate node speed state and a transmission output speed state. A clutch slip speed relationship is determined for each of the clutches based upon the node speed relationships for the planetary gear sets and the equivalent speed parameters for nodes of the planetary gear sets. Rotational speed sensors monitor the input transmission speed, the intermediate node speed and the transmission output speed. A clutch slip speed for each of the clutches is determined based upon the respective clutch slip speed relationship and the monitored input transmission speed, the monitored intermediate node speed and the monitored transmission output speed.

Abstract: A system includes a pedal override module that receives a pedal position from an accelerator pedal position sensor, receives a pedal pressure from an accelerator pedal pressure sensor, compares the pedal position to the pedal pressure, and selectively outputs a pedal override signal based on the comparison between the pedal position and the pedal pressure. A throttle position control module controls a position of a throttle based on the pedal position and the pedal override signal.

Abstract: A method of controlling a vehicle includes signaling a transmission to shift into a first gear ratio and sensing a current gear ratio of the transmission after signaling the transmission to shift into the first gear ratio. The method further includes implementing a diagnostic transmission shift control strategy to override a normal transmission shift control strategy when the current sensed gear ratio is not equal to the requested first gear ratio to verify proper functionality of a mode control valve that is responsible for shifting the transmission into the first gear ratio.

Abstract: A method of controlling a vehicle includes signaling a transmission to shift into a first gear ratio and sensing a current gear ratio of the transmission after signaling the transmission to shift into the first gear ratio. The method further includes implementing a diagnostic transmission shift control strategy to override a normal transmission shift control strategy when the current sensed gear ratio is not equal to the requested first gear ratio to verify proper functionality of a mode control valve that is responsible for shifting the transmission into the first gear ratio.

Abstract: A method of controlling a clutch-to-clutch transmission. The method includes detecting transmission slip speed that exceeds a predetermined amount for a predetermined time period. Based on the detecting, a shift of a gear ratio of the transmission is forced. When this method is implemented in a vehicle, loss of driver control of the vehicle can be prevented in the event of a non-commanded neutral condition in the transmission.

Abstract: A vehicle including a transmission having a plurality of clutches for providing a plurality of speed ratios. A control module of the vehicle detects a possible tie-up of at least two of the clutches. Based on the detecting, the control module releases one of the possibly tied-up clutches. After the release, the control module determines whether a tie-up condition occurred. Based on the determining, the control module reapplies pressure to the released clutch. Loss of driver control of the vehicle thus can be prevented in the event of clutch tie-up.

Abstract: A method of controlling a clutch-to-clutch transmission. The method includes detecting transmission slip speed that exceeds a predetermined amount for a predetermined time period. Based on the detecting, a shift of a gear ratio of the transmission is forced. When this method is implemented in a vehicle, loss of driver control of the vehicle can be prevented in the event of a non-commanded neutral condition in the transmission.

Abstract: A vehicle including a transmission having a plurality of clutches for providing a plurality of speed ratios. A control module of the vehicle detects a possible tie-up of at least two of the clutches. Based on the detecting, the control module releases one of the possibly tied-up clutches. After the release, the control module determines whether a tie-up condition occurred. Based on the determining, the control module reapplies pressure to the released clutch. Loss of driver control of the vehicle thus can be prevented in the event of clutch tie-up.