A transmission includes a stationary member, an input member, and gear sets each having a plurality of nodes. The transmission includes a first clutch that connects a node of one gear set to the stationary member to establish an L1 mode, and a second clutch that connects a node of another gear set to the stationary member to establish a 2L mode. A SOWC is connected between nodes of two gear sets, and a controller, in response to a requested shift L1-L2 shift while engine braking, executes a method to release the first clutch and thereby enters a neutral mode. The SOWC is released when slip across the first clutch exceeds a first threshold, then the first clutch reapplied when a SOWC slip level exceeds another threshold to thereby enter a 1.sup.st gear freewheeling mode. The second clutch is reapplied to enter the L2 mode and resume engine braking.

A fixed-gear transmission including a plurality of planetary gear sets and a plurality of clutches is described. A method for controlling the fixed-gear transmission includes commanding a first iteration of a skip-at-sync transmission shift and monitoring clutch slip of an oncoming holding clutch associated with the skip-at-sync transmission shift during execution of the shift, which includes monitoring synchronization of the on-coming holding clutch and a maximum clutch slip overshoot value. A progressive clutch pressure ramp rate for the oncoming holding clutch is adaptively controlled in response to the clutch synchronization of the on-coming hold clutch during execution of a subsequent iteration of the skip-at-sync transmission shift.

A method for learning a characteristic of a clutch in a DCT vehicle includes a shifting condition determination step for determining whether a shifting condition is satisfied, a synchronization step for partly reducing torque of a disengagement-side clutch in order to synchronize an engine speed with a speed of an engagement-side input shaft when shifting is started when the shifting condition is satisfied, a clutch release determination step for determining whether a slip amount of a disengagement-side clutch exceeds a reference slip amount, and a disengagement-side clutch learning step for updating clutch torque on a characteristic curve of the disengagement-side clutch using the torque of the disengagement-side clutch that is controlled to allow the slip amount of the disengagement-side clutch to exceed the reference slip amount in the clutch release determination step, and for learning the updated clutch torque.

A fixed-gear transmission including a plurality of planetary gear sets and a plurality of clutches is described. A method for controlling the fixed-gear transmission includes commanding a first iteration of a skip-at-sync transmission shift and monitoring clutch slip of an oncoming holding clutch associated with the skip-at-sync transmission shift during execution of the shift, which includes monitoring synchronization of the on-coming holding clutch and a maximum clutch slip overshoot value. A progressive clutch pressure ramp rate for the oncoming holding clutch is adaptively controlled in response to the clutch synchronization of the on-coming hold clutch during execution of a subsequent iteration of the skip-at-sync transmission shift.

A speed sensor is integrated with a bearing of a transmission. The speed sensor may sense rotation of a bearing cage using a proximity sensor or may sense passage of the rolling elements themselves using an acceleration sensor. The speed of the shaft supported by the bearing is calculated from the speed sensor reading. The shaft speed may be used to control a slipping clutch during a shift event. When the transmission is in a fixed gear ratio, inconsistent speed sensor reading may indicate a preload issue.

A vehicle transmission system includes a shift cam rotated by rotary power from an output torque of a gearshift actuator motor to change a gearshift position and a rotational position holding mechanism configured to hold a rotational position of the shift cam. The rotational position holding mechanism has a rotatable member that is rotated in synchronization with the shift cam and has a plurality of indented portions along a rotational direction and a stopper member inserted into the indented portion of the rotatable member to hold a rotational position of the rotatable member. An unindented portion between the plurality of indented portions on the outer circumferential surface of the rotatable member is formed on a circular arc curved surface concentric on a rotation center line.

An engine unit of a motorcycle has a crankcase and an overlying cylinder block. The crankcase has a magnet cover positioned outward of the cylinder block in the vehicle width direction as seen in the front-rear direction. The clutch actuator motor serving as a driving power source for a switching operation of the clutch is disposed inward of the side surface of the magnet cover in the vehicle width direction as seen in the front-rear direction. A part of the clutch actuator motor is positioned over the magnet cover.

Readings of multiple sensors are utilized to estimate transmission output, which is used as a feedback signal to control the torque capacity of a transmission clutch. Some sensor readings, such as transmission output speed, are used to compute an input vector. Then, a current state vector is computed as a linear function of the previous state vector and the input vector. One of the values in the state vector is shaft twist, which is proportional to transmission output torque. Various other sensor readings, including wheel speed, are used to correct for noise. Wheel speed signals are received with a delay. To accommodate this delay, the state vector is expanded to include estimates of wheel speed at various past points in time. An accelerometer reading is used at very low speeds at which the wheel speed sensor and transmission output speed sensor are unreliable.