Change-of-mind shift control of a dual-clutch transmission

A vehicle includes an engine, dual-clutch transmission (DCT), and controller. The controller executes a method to control a requested change-of-mind shift of the DCT to a second desired gear state. The requested shift is initiated after a prior-requested but not yet fully-executed shift of the DCT to a first desired gear state. The controller detects the requested shift, identifies the second desired gear state, and aborts the prior-requested shift immediately upon identifying the second desired gear state. The controller also shifts the DCT to the second desired gear state using a calibrated shift profile corresponding to the detected shift. The calibrated shift profile describes required oncoming and offgoing clutch torques needed for achieving the second desired gear state. Engine speed control may be used to synchronize engine and input shaft speeds.

TECHNICAL FIELD

The present disclosure relates to the control of a change-of-mind shift maneuver in a vehicle having a dual-clutch transmission.

BACKGROUND

A dual-clutch transmission (DCT) combines features of manual and automatic transmissions. In a DCT, a first input clutch is applied to engage oddly-numbered gear sets of a gearbox, i.e., 1st, 3rd, 5th, and 7thgear, while a second input clutch is applied to engage the evenly-numbered gear sets such as 2nd, 4th, 6th, and Reverse gear. A transmission control module predicts the next-selected or desired gear using various available control inputs such as engine acceleration and braking levels. The transmission control module then commands engagement of a fork synchronizer used for the desired gear ahead of application of the input clutch for that particular gear. The unique structure of a DCT may provide faster shift speeds relative to a conventional automatic transmission, with improved overall shift control and increased power.

SUMMARY

A system is disclosed herein that includes a dual-clutch transmission (DCT) and a controller. The controller is programmed to control a change-of-mind shift of the DCT when used in a vehicle as set forth herein. The term “change-of-mind shift” refers to a requested shift to another gear state that initiates before the completion of a prior-requested shift. For instance, a driver may change throttle and/or braking levels during the course of a prior-requested shift. The changed driver inputs can result in a new optimal transmission state, and thus the initiation of a different shift maneuver.

If the controller were to wait for the prior-requested shift to complete in the conventional manner before reacting to the changed driver inputs, the driver may perceive a hesitation or lag in the shift. The controller is therefore programmed as set forth herein to account for multiple different possible change-of-mind shifts via application of a selected calibrated clutch torque profile, with engine speed controls also used in some instances depending on the particular change-of-mind shift. The method performed by the controller allows a requested shift to a new gear state to be immediately aborted mid-shift. The control sequences described herein quicken the transition to the newly-requested gear state. To the extent possible, power flow is maintained through the driveline to provide a seamless transition to the newly-requested gear state. This in turn minimizes driveline disturbances while improving shift responsiveness, as well as providing continuous vehicle acceleration through the shift, when applicable.

In an example embodiment, the vehicle includes an internal combustion engine, a DCT, and a controller. The DCT includes a pair of input clutches, first/odd and second/even input shafts, and a gearbox containing separate oddly-numbered and evenly-numbered gear sets on the corresponding first and second shafts. Application of a designated one of the input clutches connects the engine to a corresponding one of the oddly-numbered or evenly-numbered gear sets on one of the two input shafts of the DCT. The controller, which is in communication with the two input clutches, includes a processor and tangible, non-transitory memory on which is recorded instructions for executing a change-of-mind shift from a first desired gear state to a second desired gear state.

In this embodiment, execution of the instructions causes the controller to detect the change-of-mind shift and identify the second desired gear state. The controller also aborts the initially-requested shift to the first desired gear state immediately upon identifying the second desired gear state, that is, without waiting for the prior-requested shift to the first desired gear state to complete in the conventional manner. The controller commands a shift of the DCT to the second desired gear state via a calibrated shift profile corresponding to the detected change-of-mind shift, i.e., a stored torque handoff profile describing the required oncoming and offgoing clutch torques for achieving the second desired gear state. Engine speed control may also be used in controlling some shift maneuvers.

The controller is programmed with a plurality of different calibrated shift profiles, including a profile for one or more power-on downshift-to-power-on downshift maneuvers, an upshift-to-power-on downshift maneuver, a coasting downshift-to-power-on downshift maneuver, an upshift-to-coasting upshift maneuver, a quick shift-to-quick shift maneuver, and a torque interrupt-to-power-on downshift maneuver. In such an embodiment, engine speed control may be used as part of the quick shift-to-quick shift and tip-in-to-power-on downshift maneuvers.

The power-on downshift-to-power-on downshift maneuvers may include a first shift maneuver to the first or second input shaft of the DCT from the same first or second input shaft and a second shift maneuver from the first input shaft to the second input shaft/from the second input shaft to the first input shaft.

The controller is programmed to shift the DCT to the second desired gear state via the calibrated shift profile by dropping clutch torque/torque capacity for a designated offgoing clutch according to a calibrated clutch exhaust profile immediately upon synchronization of engine speed with a speed of the particular input shaft of the DCT used for achieving the second desired gear state.

A temporary increase in engine speed may be requested by the controller, such as via transmission of a request to an engine control module, after detecting the change-of-mind shift in order to synchronize engine speed with input shaft speed.

A system and method are also disclosed. The system includes the DCT and the controller noted above. The method includes detecting the requested change-of-mind shift, including processing driver inputs via the controller, and identifying the second desired gear state. The method also includes aborting the prior-requested shift to the first desired gear state immediately upon identifying the second desired gear state and automatically shifting the DCT to the second desired gear state using a calibrated shift profile corresponding to the detected change-of-mind shift. The calibrated shift profile describes the required oncoming and offgoing clutch torques needed for achieving the second desired gear state.

The above features and advantages, and other features and advantages, of the present disclosure are readily apparent from the following detailed description of some of the best modes and other particular, embodiments for carrying out the invention, as defined in the appended claims, when taken in connection with the accompanying drawings.

DETAILED DESCRIPTION

Referring to the drawings, wherein like reference numbers refer to like components throughout the several Figures, an example vehicle10is shown schematically inFIG. 1. The vehicle10includes an internal combustion engine (E)12and a dual-clutch transmission (DCT)14. The engine12is responsive to a received throttle level (arrow Th %) requested via a force applied to, or a corresponding percentage of travel of, an accelerator pedal3M. The throttle level (arrow Th %) requests a relative level of input torque (arrow TI) from the engine12. The force/travel of the accelerator pedal3M may be measured via a force or position sensor (SP) in the conventional manner. The engine12also responds to a braking level (arrow B %) from a brake pedal13B, with the braking level (arrow B %) likewise detected via a force or position sensor (SP). In response to receipt of the throttle level (arrow Th %) by a controller (C)16, e.g., an engine control module, the engine12delivers the input torque (arrow TI) to the DCT14via an input member15, or more precisely, one of two different input members15E and15O.

As explained below with reference toFIGS. 2 and 3A-G, the controller16is configured, i.e., specially programmed in software and equipped in hardware, to control various change-of-mind shifts of the DCT14in a manner that reduces shift delays and harshness. As used herein, the term “change-of-mind shift” refers to any shift of the DCT14from one speed ratio to another initiated after a prior-requested but not yet fully-executed shift. That is, driver inputs such as throttle level (arrow Th %) and braking level (arrow B %) may change during the course of a requested shift. Changes in driver input can result in a new optimal transmission state, which in turn would require a new shift to be initiated. The method100ofFIG. 2as implemented via the time plots ofFIGS. 3A-Gis intended to ensure that the change-of-mind shifts occur quickly and smoothly relative to conventional delayed approaches.

The example DCT14ofFIG. 1may be include a gearbox17and two independently-operated, non-lubricated respective first and second input clutches C1and C2. While omitted fromFIG. 1for illustrative clarity, each input clutch C1and C2may include a center plate containing spaced friction discs, plates, or other suitable friction devices. The input clutches C1and C2are selectively compressed together via a fluid-actuated clutch piston or other suitable clutch actuator(s) (not shown), with these pistons having an axial position that is used in the overall control of the input clutches C1and C2. Associated electronic and hydraulic clutch control devices (not shown) ultimately control the shift operations of the DCT14, including change-of-mind shifts as noted above, in response to instructions or commands from the controller16.

In the example DCT14, the first input clutch C1may be used to connect the engine12to any of the oddly-numbered gear sets16A,16B,16C, and16D, each having a node connected to a stationary member28of the DCT14, for instance to establish respective fifth (5th), third (3rd), first (1st), and seventh (7th) gears in the example 7-speed transmission design ofFIG. 1. The second input clutch C2connects the engine12to reverse or any of the respective evenly-numbered gear sets16E,16F, and16G, e.g., fourth (4th), second (2nd), and sixth (6th) gears in the same example 7-speed transmission, as well as a reverse gear set16H. Clutch forks and synchronizers19are shown schematically for the various gear sets. Using this type of gear arrangement, the DCT14can be rapidly shifted through its available range of gears without completely interrupting the power flow from the engine12.

In the example vehicle10ofFIG. 1, the DCT14also includes an output member20that is connected to a set of drive wheels (not shown). The output member20ultimately transmits output torque (arrow To) from the DCT14to the drive wheels in order to propel the vehicle10. The DCT14may include a first input shaft21that is connected to the output side of the first input clutch C1, and also a second input shaft23that is connected to the output side of the second input clutch C2. The first input shaft21is connected to only the oddly-numbered gear sets16A,16B,16C, and16D. Likewise, the second input shaft23is connected to only the evenly-numbered gear sets16E,16F, and16G and the reverse gear set16H. The DCT14further includes upper and lower main shafts31A and31B, respectively, which may be connected to respective final drive gear sets32A and32B. The final drive gear sets32A and32B provide any required final gear reduction.

The controller16ofFIG. 1may be embodied as a microprocessor-based computing device or devices having a processor P and memory M, including but not necessarily limited to magnetic or optical read only memory (ROM), random access memory (RAM), electrically-erasable programmable read-only memory (EEPROM), flash memory, etc., and any required circuitry. The circuitry may include high-speed clocks, analog-to-digital (A/D) circuitry, digital-to-analog (D/A) circuitry, a digital signal processor, transceivers configured to transmit and receive any required signals during the overall control of the DCT14, and the necessary input/output (I/O) devices and other signal conditioning and/or buffer circuitry.

The controller16determines or processes driver inputs such as throttle level (arrow Th %), braking level (arrow B %), vehicle speed (arrow Nx), the attained gear (arrow AG), i.e., the gear state the DCT14is currently in, and a desired gear (arrow DG) to be attained. The controller16ultimately outputs a clutch position control signal (arrow Px) to the designated input clutch C1or C2for a given shift to set the position of the designated input clutch C1or C2, and fork control signals (arrow FN) to the corresponding clutch forks and synchronizers19for the desired gear. Thus, the input clutches C1and C2are referred to as “position-controlled” clutches.

The clutch position control signal (arrow Px) sets the axial or linear position of a clutch apply piston or other actuator device of the input clutch C1or C2for applying the input clutch C1or C2, whichever one acts as the oncoming clutch during a requested shift. A torque-to-position (TTP) table and calibrated torque profiles30, for instance the example profiles30A-G ofFIGS. 3A-G, respectively, may be recorded in memory M of the controller16and referenced to determine the required apply position for the input clutches C1and C2, as is well known in the art of position-controlled clutches.

Referring toFIG. 2, an example embodiment of the method100is shown. The controller16ofFIG. 1executes logic embodying the method100from its memory M to quickly attain the gear state requested in a change-of-mind shift as noted above, while continuously transmitting torque to the drive wheels of the vehicle10.

The method100begins with step102, wherein the controller16ofFIG. 1detects a requested shift to a first desired gear state (DET GS1) of the DCT14. The shift to the first desired gear state (GS1) may be detected by the controller16by processing all available inputs via the processor P, typically the throttle level (arrow Th %), braking level (arrow B %), attained gear (arrow AG), vehicle speed (arrow Nx), desired gear (arrow DG), and any other useful information such as input speed and output speed, i.e., from respective input and output speed sensors (not shown) positioned with respect to the shafts/members21,23, and20. Step102also entails determining the type of shift that is requested, such as a power-on downshift, an upshift, a coasting downshift, a quick/tap shift, a quick shift-to-quick shift maneuver, and a torque interrupt-to-power-on downshift, all of which are explained with respect toFIGS. 3A-Gbelow. The method100proceeds to step104once the first requested gear shift is detected and identified.

At step104, the controller16continues to process the throttle level (arrow Th %) and other driver inputs from step102, and determines the desired gear state (GSd), i.e., the second desired gear state (GS2) to be achieved. As is known in the art of transmission controls, step104may entail calculating the speed ratio of the DCT14in response to the various inputs and identifying the desired gear state (GSd) from this determination, whether via calculation or by accessing a calibrated shift table. The method100proceeds to step106once the desired gear state (GSd) is known.

Step106includes comparing the desired gear state (GSd) of step104to the first desired gear state (GS1) from step102. If the desired gear state (GSd) and the first desired gear state (GS1) are different, the controller16determines that a change-of-mind shift (Δ) has been detected and proceeds to step110. The controller16proceeds to step108in the alternative if the desired gear state (GSd) and the first desired gear state (GS1) of step102are the same gear state.

At step108, the controller16ofFIG. 1executes the initially-requested gear shift, i.e., the first desired gear state (GS1) of step102, in the usual manner. Step108may include, for instance, applying the corresponding input clutch C1or C2via transmission of the clutch position control signals (arrow Px) to the clutch actuator used for the input clutch C1or C2, as well as hydraulic control of the associated forks and synchronizer(s)19needed for the requested shift. The DCT14shifts into the first desired gear state (GS1). The method100begins anew at step102.

At step110, the controller16immediately aborts the initially-requested shift to the first desired gear state (GS1) from step102and instead executes the change-of-mind shift to quickly enter the newly-requested/second desired gear state (GS2). Via execution of step110, the controller16determines the oncoming and offgoing clutch torques needed for designated oncoming and offgoing clutches of the DCT14to achieve the new desired gear state and transmits the clutch position control signals (arrow Px) to the particular input clutch C1and/or C2involved in the change-of-mind shift. In some embodiments, step110may also include requesting speed control of the engine12as described below with reference toFIGS. 3F and 3G.

Step110also includes selecting a calibrated profile30A-G ofFIGS. 3A-G, respectively, for the specific type of change-of-mind shift. The calibrated profiles30A-G determine both the timing and the magnitude of the clutch torques and various shaft speeds needed for quickly achieving the change-of-mind shift. Example profiles30A-G will now be explained with reference to respectiveFIGS. 3A-G.

FIGS. 3A and 3Bdepict power-on downshift-to-power-on downshifts labeled as PDXPD1 and PDXPD2, respectively. The shift described by the calibrated shift profile30A ofFIG. 3Ais a shift to the same input shaft21or23. The shift of the calibrated shift profile30B ofFIG. 3Bis a shift to a different shaft21or23. An example shift inFIG. 3Ais an initially-requested 5-4 power-on downshift in which a driver changes some inputs mid-shift to thereby request a 5-3 power-on downshift. In a 5-3 power-on downshift, the initially-requested gear state (5thgear) and the newly-requested gear state (3rdgear) are both oddly-numbered gear states, and thus the gear sets16A and16B are on the same shaft, i.e., input shaft21as shown inFIG. 1. The shift ofFIG. 3Bby comparison could be, for instance, a 6-5 power-on downshift changed mid-shift to a 6-3 power-on shift such that the input shaft must change from even (6th) to odd (3rd), i.e., from the input shaft23to the input shaft21.

Power-on downshifts are referred to in the art as “offgoing clutch-controlled shifts”. That is, the designated offgoing clutch is position-controlled to affect the torque handoff from the offgoing clutch to the designated oncoming clutch. However, in the profile30A shown inFIG. 3A, which is a “same-shaft” power-on downshift as noted above, there are two different controlling clutches: the first input clutch C1for achieving the initially-requested gear state and the second input clutch C2for achieving the newly-requested/second desired gear state (GS2).

An input to the controller16ofFIG. 1is the initial desired gear (trace DG). This value corresponds to the desired gear (arrow DG) ofFIG. 1. A shift to the initially-requested or first desired gear state (GS1) is ongoing between t0and t1, with the change-of-mind shift being detected at about point35. The newly-requested/second desired gear state (GS2) initiated via a change-of-mind shift commences at t2and continues until t4. Also shown inFIG. 3Ais a first shaft speed (trace N1) describing the rotational speed of the input shaft21, a second shaft speed (trace N2) describing the rotational speed of the input shaft23, and an input speed (trace N1) which is the rotational speed of the input member15ofFIG. 1, or the speed of the engine12ofFIG. 1. The particular input shafts21,23used for the first and second shaft speeds (traces N1and N2, respectively) will vary in other shift maneuvers. Clutch torques (traces TC1and TC2) are also shown indicating the clutch torque capacity of the input clutches C1and C2ofFIG. 1, respectively, along with a calibrated ramp profile (trace RCAL) as discussed below.

Absent execution of the present method100, the normal synchronization point for a change-of-mind shift would be reached at about t2, as indicated by point37. However, the controller16upon detecting the change-of-mind shift at point35per step106ofFIG. 2executes the calibrated ramp profile (trace RCAL) shortly before t2as shown. The profile or slope of trace RCALis predetermined and stored in memory M of the controller16to provide the desired shift feel, with a steeper ramp producing a faster change in input speed (trace N1), i.e., engine speed. Torque is handed off from input clutch C1, which is the offgoing clutch for the initially-requested shift, to the input clutch C2, i.e., the oncoming clutch.

At about t3, the first shaft speed (trace N1) is at its required level. The first shaft speed (trace N1) and the input speed (trace N1) to the DCT14are synchronized at point39. The change-of-mind shift first detected at point35is thus ready to occur at about t3. The clutch torque (trace TC2) for input clutch C2, which is the offgoing clutch for the change-of-mind shift shown inFIG. 3A, is rapidly dropped between t3and t4according to a calibrated clutch exhaust profile45. Torque capacity of the oncoming clutch, which is the input clutch C1in this example, rapidly rises shortly after t3. The change-of-mind shift is completed at about t4, with the DCT14thereafter operating in the newly-requested/second desired gear state (GS2).

FIG. 3Bshows the shift ofFIG. 3Afor a slightly different “PDXPD2” shift. As noted above, inFIG. 3Bthe PDXPD2 shift is a power-on-to-power-on downshift maneuver occurring to the opposite input shaft21or23, e.g., a 6-5 power-on downshift with a change of mind to a 6-3 power-on downshift. Here, the same offgoing clutch, which is the input clutch C1in this example, controls the entire shift. For the example 6-5 initially-requested power-on downshift, 5thgear is attained at about point41, with the change-of-mind shift detected slightly earlier at point35.

Upon detection of the change-of-mind shift the controller16ofFIG. 1controls slip of the input clutch C1in a slip control region47, such as by using proportional-integral-derivative control logic of the controller16. In the slip control region47, the controller16commands pressure to a required clutch fork for 3rdgear, that is, the change-of-mind gear first detected at point35via execution of step104ofFIG. 2. Thereafter, torque is offloaded according to exhaust profile45from the offgoing clutch, which is input clutch C1, to the oncoming clutch or input clutch C2. The change-of-mind shift is complete at t4.

FIG. 3Cdepicts another calibrated profile30C for a change-of-mind shift from an upshift-to-power-on downshift (US2PD) maneuver. Typical trajectories are shown for input speed (trace NI*) and shaft speed (trace N1*) absent execution of the method100. The calibrated shifts profile30C, as with the calibrated shift profiles30A and30B of respectiveFIGS. 3A and 3Bdescribed above, detects the change-of-mind shift at about point35. Thereafter, the calibrated ramp profile (trace RCAL) is executed for this shift to offload torque from the offgoing clutch, i.e., the input clutch C2in this example, to the oncoming clutch/input clutch C1. The process of offloading torque according to the profile30C is via access to the TTP table (TTP) ofFIG. 1, with the corresponding position for the respective input clutches C1and C2being extracted from the TTP table and commanded via the clutch position control signals (arrow Px) ofFIG. 1.

As torque is offloaded from the input clutch C2, the first shaft speed (trace N1) rises shortly after t2along with the input speed (trace N1), with the input speed (trace N1) lagging behind the first shaft speed (trace N1). The input speed (trace N1) and the first shaft speed (trace N1) are the same, i.e., synchronized, at point39. As in this example the input shaft23is not used and the second shaft speed (trace N2) remains at or near zero. After point39, exhaust profile45is executed to drop the clutch torque (trace TC2) for the offgoing clutch and raise clutch torque (trace TC1) for the oncoming clutch, thereafter completing the change-of-mind shift at t4.

FIG. 3Ddepicts a calibrated profile30D for a change-of-mind shift from a coasting downshift-to-power-on downshift (CD2PD) maneuver. Trajectories are shown for input speed (trace N1) and the first shaft speed (trace N1). The calibrated profile30D detects the change-of-mind shift at point35during the initially-requested/first desired gear state (GS1). Prior to t2, the controller16drops the clutch torque (trace TC1) for the offgoing clutch C1for this maneuver while increasing the clutch torque (trace TC2) for the oncoming clutch C2. For comparison, the trace TC2* depicts the ordinary trajectory of oncoming clutch torque TC2absent the method100. That is, the clutch torque TC2would not plateau until about t2. In executing the method100, however, clutch torque plateaus immediately upon detection of the change-of-mind shift at point35.

The calibrated profile (trace RCAL) is executed and the clutch torques (traces TC1and TC2) are held steady until the input speed (trace N1) and the first shaft speed (trace N1) are synchronized just before t3. At point39, which coincides with the synchronizing of the speeds (trace N1and N1), the controller16increases the clutch torque (trace TC2), holds this increased clutch torque for a calibrated duration, and executes the exhaust profile45to quickly release the offgoing clutch, which is the input clutch C2in this example. The controller16then commands application of the oncoming clutch C1via the clutch position control signals (arrow Px). The change-of-mind shift is complete at t4.

FIG. 3Eshows yet another change-of-mind shift maneuver, this time a power-on downshift-to-coasting upshift (PD2CU) maneuver, which is essentially the opposite shift maneuver from that shown inFIG. 3D. Trajectories are shown for input speed (trace NI) and first shaft speed (trace N1). Again, the second shaft speed (trace N2) is steady or zero, as it has no role to play in the shift of calibrated shift profile30E. The calibrated shift profile30E detects the change-of-mind shift at point35during the shift to the first desired gear state (GS1). The controller16executes the calibrated ramp (trace RCAL) prior to t2. The controller16drops the clutch torque (trace TC1) for clutch C1while holding the clutch torque (trace TC2) steady for clutch C2. The change-of-mind shift at point35is detected. The input clutch C2is not required in a coasting upshift involving the input clutch C1, and thus the controller16ramps down the clutch torque (trace TC2) to zero at a calibrated ramp suitable for optimizing feel of the release. The input clutch C2is thereafter uninvolved in the maneuver.

At about t2, the falling input speed (trace N1) coincides with the first shaft speed (trace N1). At this point, the controller16quickly drops clutch torque (trace TC1) to a minimal level as shown before slowly increasing the clutch torque (trace TC1) at a first rate until point39is achieved, i.e., the input speed (trace N1) and first shaft speed (trace N1) are synchronized. At this point, around t3, the controller16ramps clutch torque of the input clutch C1to full capacity as shown, with the shift maneuver completed at t4.

FIGS. 3F and 3Gdescribe two additional change-of-mind shifts of the DCT14ofFIG. 1.FIGS. 3F and 3Gdiffer fromFIGS. 3A-3Ein part due to the use of speed control of the engine12to enforce the respective shift profiles30F and30G. Referring first toFIG. 3F, the calibrated shift profile30F depicts a quick shift-to-quick shift (QS2QS) maneuver, which is any tap downshift during intervals of little to no acceleration of the engine12, i.e., an “engine speed-matched downshift”. As withFIGS. 3A-E, trajectories are shown for input speed (trace N1) and first and second input shaft speeds (respective traces N1and N2).

The prior-requested shift to the first desired gear state (GS1) progresses between t1and t4. According to the calibrated profile30F, clutch torque (trace TC1) for the offgoing clutch for the first desired gear state (GS1) is ramped down to zero between t1and t2, reaching zero at t2. The oncoming clutch for the first desired gear state (GS1), here the input clutch C2, is quickly stepped up to a calibrated level at t3midway through the shift to the first desired gear state (GS1). The affected speeds (traces N1, NI) ramp upward at a calibrated rate in response to the changing clutch torques.

Per the calibrated profile30F, however, the first shift request is not allowed to complete upon detection of the change-of-mind shift at point35. Instead, upon detection of the change-of-mind shift at point35the controller16immediately aborts the initially-requested shift at t4, drops the clutch torque (trace TC2) back to zero, and steps up the clutch torque (trace TC1) for the prior offgoing clutch, i.e., input clutch C1, which now acts as the oncoming clutch for the change-of-mind shift in this example.

The controller16requests speed control of the engine12at about t5, such as via request transmitted to an engine control module (not shown) if the controller16is limited to being a transmission control module, which causes the input speed (trace N1) to rise at a calibrated rate. Synchronization of the input speed (trace N1) and the second shaft speed (trace N2) occurs at point39. Upon synchronization, the controller16ofFIG. 1increases oncoming clutch torque (trace TC1) at a calibrated ramp rate (RCAL) at about t6, once again via transmission of the clutch position control signals (arrow Px) to the affected clutches C1and C2. A calibrated amount of time after synchronization, the controller16rapidly increases oncoming clutch torque, e.g., at t7, and completes the change-of-mind shift to the second desired gear state (GS2).

The calibrated shift profile30G ofFIG. 3Gdepicts a torque interrupt-to-power-on downshift (TI2PD) maneuver. The prior-requested shift to the first desired gear state (GS1) progresses between t1and t3. According to the calibrated shift profile30G, the clutch torque (trace TC1) for the offgoing clutch for the shift to the first desired gear state (GS1) is ramped down to zero between t1and t2, reaching zero at t2. The oncoming clutch for the first desired gear state (GS1), i.e., the input clutch C2, is ramped up to a calibrated level between t2and t3midway through the shift to the first desired gear state (GS1). During this same interval, the first shaft speed (trace N1) increases along with the input speed (trace N1), i.e., the speed of the engine12, with the input speed (trace N1) becoming synchronized with the first shaft speed (trace N1) at about point39.

Upon detection of the change-of-mind shift at point35the controller16immediately aborts the initially-requested shift at t3, decreases the clutch torque (trace TC2) at a calibrated rate and holds the clutch torque (trace TC1) for the prior offgoing clutch, i.e., input clutch C1, at zero until t6. Decreasing the clutch torque (trace TC2) causes the input speed (trace N1) to again rise at a calibrated rate. This rise in input speed (trace N1), as indicated by arrow41, continues until about t6. Synchronization of the input speed (trace N1) and the second shaft speed (trace N2) occurs at point139.

Upon such synchronization, the controller16ofFIG. 1increases oncoming clutch torque (trace TC1) and drops offgoing clutch torque (trace TC2) as in the clutch exhaust profile45, once again via transmission of the clutch position control signals (arrow Px) to the affected input clutches C1and C2. The change-of-mind shift is completed at about t7.

Using the method100, the controller16can apply any of the shift profiles30A-30G ofFIGS. 3A-Gto quickly react to changing driver inputs through a wide range of change-of-mind shifts. The controller16is therefore configured to eliminate actual or perceived delay in the change-of-mind shift, thereby optimizing shift feel relative to conventional approaches. Continuous torque is transmitted during the change-of-mind shift, which in turn can limit driveline disturbances.

The detailed description and the drawings or figures are supportive and descriptive of the invention, but the scope of the invention is defined solely by the claims. While the best mode, if known, and other embodiments for carrying out the claimed invention have been described in detail, various alternative designs and embodiments exist for practicing the invention defined in the appended claims.