Method for controlling the powertrain of a vehicle during changing driving conditions

Abstract

Method for setting the operation of a hybrid vehicle, the method comprising: setting a plan for automatically stopping a power engine rotation in response to a road surface condition, further comprising setting an opening of a disengagement clutch (236) of a powertrain (200) in response to the road surface condition, wherein the opening of the disengagement clutch (236) of the powertrain (200) occurs in accordance with a first plan in response to the hybrid vehicle being in a two-wheel drive mode, and wherein the opening of the disengagement clutch (236) of the powertrain (200) occurs in accordance with a second plan, the second plan being different from the first plan, in response to the hybrid vehicle being in a four-wheel drive mode.

Description

Field of InterestThe present description relates to systems and methods for improving vehicle drivability and fuel economy. The methods may be particularly useful for engines selectively coupled to an electric machine and a transmission.Background and SummaryHybrid vehicles potentially provide improvements in vehicle fuel economy and driving range over non-hybrid vehicles. One way to further improve fuel economy is to stop operation of the engine. However, when engine operation has been completed, less than the full torque output of the vehicle driveline may be available to avoid undesired road conditions. Therefore, stopping engine rotation to conserve fuel may reduce the possibility that a driver may have a desired amount of driveline torque to avoid a particular road condition.A hybrid vehicle and a method for controlling its drive train with a changing route profile is disclosed in DE 100 35 027 A1. DE 10 2007 000 331 A1 discloses a control method for a hybrid vehicle in which it is observed when a request for a start or stop of an internal combustion engine of a hybrid vehicle is made whether the hybrid vehicle becomes unstable.The invention is based on the object of improving the drivability of the hybrid vehicle even in particular road conditions by controlling a drive train of a hybrid vehicle. According to the invention, the object is achieved by a method according to claim 1. Advantageous refinements of the invention are specified in the dependent claims.By setting a map to automatically stop an engine in response to the conditions of the roadway, it may be possible to reduce a time period between a request for additional wheel torque and the time the torque is actually delivered to the vehicle wheels. In one example, the engine decoupled from a driveline of the vehicle may be allowed to idle, rather than coming to a full stop when road conditions have degraded. By allowing the engine to idle, it is avoided to have to restart the engine. Thus, torque output from the engine to the driveline of the vehicle may be made available in a more timely manner.The present description may provide several advantages. Specifically, the technique may reduce a time period required to provide a higher wheel torque. Further, the approach may improve vehicle drivability. Still further, the approach may reduce driveline wear and thereby increase driveline operating life.The above advantages and other advantages and features of the present specification will become readily apparent from the following detailed description when taken alone or in conjunction with the accompanying drawings.It should be understood that the summary above is provided to introduce a selection of the concepts in simplified form that are further described in the detailed description. It is not intended to identify key or essential features of the claimed subject matter, the scope of which is clearly defined by the claims that follow the detailed description. Moreover, the claimed subject matter is not limited to implementations that eliminate all of the disadvantages recited above or in any part of this disclosure.Brief Description of the DrawingsThe advantages described herein are more fully understood by reading an example of an embodiment referred to herein as the detailed description when considered alone or with reference to the drawings, wherein: FIG. 1 is a schematic diagram of an engine; FIG. 2 shows a first example vehicle powertrain configuration; FIG. 3 shows a second example vehicle powertrain configuration; FIG. 4 is a first portion of a flow chart for controlling a driveline of a hybrid vehicle; FIG. 5 is a second portion of the flow chart for controlling the driveline of the hybrid vehicle; FIG. 6 is a third portion of the flow chart for controlling the driveline of the hybrid vehicle; FIG. 7 is a fourth portion of the flow chart for controlling the driveline of the hybrid vehicle; FIG. 8 is a fifth portion of the flow chart for controlling the driveline of the hybrid vehicle; FIG. 9 is a sixth portion of the flow chart for controlling the driveline of the hybrid vehicle; FIG. 10 is a seventh portion of the flow chart for controlling the driveline of the hybrid vehicle; FIG. 11 is an example predicted flow for operating a vehicle including a PTO; FIG. 12 is an example predicted flow for operating a vehicle including a low gear mode in the 4×4 range; and FIG. 13 is a predicted example flow for operating a vehicle in response to a roadway.DETAILED DESCRIPTIONThe present description relates to controlling a driveline of a hybrid vehicle. The hybrid vehicle may include an engine and an electric machine as shown in FIGS. 1-3. The engine may be operated with or without a driveline integrated starter / generator (DISG) during vehicle operation. The driveline integrated starter / generator is integrated into the driveline on the same axis as the engine crankshaft and rotates whenever the torque converter drive wheel rotates. Further, the DISG may not be selectively engaged or disengaged to the driveline. Instead, the DISG is an integral part of the driveline. Still further, the DISG may be operated with or without operating the engine. The mass and inertia of the DISG remain at the driveline when the DISG is not operating to provide torque to the driveline or absorb torque from the driveline. The driveline of the vehicle may be operated in accordance with the method shown in FIGS. 4-10. FIGS. 11-13 show example operations of the vehicle in accordance with the method shown in FIGS. 4-10.In FIG. 1, an internal combustion engine 10 including a plurality of cylinders, one cylinder of which is shown in FIG. 1, is controlled by an electronic engine controller 12. The engine 10 includes a combustion chamber 30 and cylinder walls 32 with a piston 36 positioned therein and connected to a crankshaft 40. A flywheel 97 and a ring gear 99 are coupled to the crankshaft 40. The starter 96 includes a pinion shaft 98 and a pinion gear 95. the pinion shaft 98 can selectively advance the pinion gear 95 to engage the ring gear 99. The starter 96 may be mounted directly on the front of the engine or the rear of the engine. In some examples, the starter 96 may selectively provide torque to the crankshaft 40 via a belt or chain. In one example, the starter 96 is in a base state when not engaged with the crankshaft of the engine. Combustion chamber 30 is shown communicating with intake manifold 44 and exhaust manifold 48, respectively, via intake valve 52 and exhaust valve 54. Each intake and exhaust valve may be actuated by an intake cam 51 and an exhaust cam 53. The position of the intake cam 51 may be determined by the intake cam sensor 55. The position of the exhaust cam 53 may be determined by the exhaust cam sensor 57.Fuel injector 66 is shown positioned to inject fuel directly into cylinder 30, which is known to those skilled in the art as direct injection. Alternatively, fuel may be injected into an intake passage, known to those skilled in the art as port injection. The fuel injector 66 outputs liquid fuel in proportion to the pulse width of the signal FPW from the controller 12. Fuel is supplied to fuel injector 66 through a fuel system (not shown) including a fuel tank, a fuel pump, and a fuel rail (not shown). Operating current is supplied to fuel injector 66 from driver 68, which responds to controller 12. Intake manifold 44 is also shown communicating with an optional electronic throttle 62 that adjusts a position of a throttle plate 64 to control airflow from air inlet 42 to intake manifold 44. In one example, a low pressure direct injection system may be used in which fuel pressure may be increased to about 20-30 bar. Alternatively, a two-stage high pressure fuel system may be used to generate higher fuel pressures. In some examples, throttle 62 and throttle plate 64 may be positioned between intake valve 52 and intake manifold 44 such that throttle 62 is a port throttle.The manifoldless ignition system 88 provides spark to the combustion chamber 30 via a spark plug 92 in response to the controller 12. Universal exhaust gas oxygen (UEGO) sensor 126 is shown coupled to exhaust manifold 48 upstream of catalyst 70. Alternatively, the UEGO sensor 126 may be replaced with a two-state exhaust oxygen sensor.Vehicle wheel braking or regenerative braking via a DISG may be provided when a brake pedal 150 is applied via a foot 152. A brake pedal sensor 154 provides a signal indicative of brake pedal position to the controller 12.Converter 70 may include multiple catalyst building blocks, in one example. In another example, multiple exhaust control devices, each with multiple bricks, may be used. In one example, converter 70 may be a three-way catalyst.Controller 12 is shown in FIG. 1 as a conventional microcomputer including: microprocessor unit 102, input / output ports 104, read-only memory 106, random access memory 108, keep alive memory 110, and a conventional data bus. Controller 12 is shown receiving various signals from sensors coupled to engine 10, in addition to those signals previously discussed, including: an engine coolant temperature (ECT) from a temperature sensor 112 coupled to cooling sleeve 114; a position sensor 134 coupled to an accelerator pedal 130 for sensing force applied by foot 132; a measurement of engine manifold pressure (MAP) from a pressure sensor 122 coupled to intake manifold 44; an engine position sensor from a Hall effect sensor 118 sensing position of crankshaft 40; a measurement of mass of air entering the engine from sensor 120; and a measurement of throttle position from a sensor 58; atmospheric pressure may also be sensed for processing by controller 12 (the sensor not shown). In a preferred aspect of the present description, an engine position sensor 118 generates a predetermined number of equi-spaced pulses every revolution of the crankshaft from which the engine speed (RPM) can be determined.In some examples, the engine may be coupled to an electric motor / battery system in a hybrid vehicle, as shown in FIGS. 2 and 3. Further, in some examples, other engine configurations may be used, e.g., a diesel engine.During operation, each cylinder in engine 10 typically undergoes a four stroke cycle: the cycle includes the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke. Generally, during the intake stroke, the exhaust valve 54 closes and the intake valve 52 opens. Air is introduced into the combustion chamber 30 via the intake manifold 44, and the piston 36 moves toward the bottom of the cylinder to increase the volume in the combustion chamber 30. The position at which the piston 36 is near the bottom of the cylinder and at the end of its stroke (e.g., when the combustion chamber 30 is at its largest volume) is commonly referred to by those skilled in the art as bottom dead center (BDC, UT). During the compression stroke, the intake valve 52 and the exhaust valve 54 are closed. The piston 36 moves toward the cylinder head to compress the air in the combustion chamber 30. The point at which the piston 36 is at the end of its stroke and closest to the cylinder head (e.g., when the combustion chamber 30 is at its smallest volume) is commonly referred to by those skilled in the art as top dead center (TDC, OT). In a process hereinafter referred to as injection, the fuel is introduced into the combustion chamber. In a process hereinafter referred to as ignition, the injected fuel is ignited by known ignition means such as a spark plug 92, resulting in combustion. During the power stroke, the expanding gases push the piston 36 back to the BDC. The crankshaft 40 converts the piston motion into a torque of the rotary shaft. Finally, during the exhaust stroke, the exhaust valve 54 opens to expel the combusted air-fuel mixture to the exhaust manifold 48, returning the piston to TDC. It should be noted that the above has been shown merely as an example and that intake and exhaust valve opening and / or closing timings may change, such as to provide positive or negative valve overlap, late intake valve closing, or various other examples.FIG. 2 is a block diagram of a driveline 200 of a vehicle. Driveline 200 may be driven by engine 10. The engine 10 may be started with an engine starting system shown in FIG. 1 or via a DISG 240. Further, engine 10 may generate or adjust torque via a torque actuator 204 such as a fuel injector, throttle, etc.An engine output torque may be transmitted to an input side of a dual mass flywheel 232. Both the engine speed and the position and speed of the input side of the dual mass flywheel may be determined via the engine position sensor 118. The dual mass flywheel 232 may include springs (not shown) and separate masses to dampen driveline torque disturbances. The output side of the dual mass flywheel 232 is shown mechanically coupled to the input side of the disconnect clutch 236. The disconnect clutch 236 may be electrically or hydraulically actuated. A position sensor 234 is positioned on the disconnect clutch side of the dual mass flywheel 232 to sense the home position and the rotational speed of the dual mass flywheel 232. The downstream side of disconnect clutch 236 is shown mechanically coupled to DISG input shaft 237.The DISG 240 may be operated to provide torque to driveline 200 or to convert driveline torque to electrical energy to be stored in an electrical energy storage device 275. The DISG 240 has a higher output power capacity than the starter 96 shown in FIG. 1, and further, the DISG 240 directly drives or is directly driven by driveline 200. There are no belts, gears, or chains to couple the DISG 240 to driveline 200. Instead, the DISG 240 rotates at the same speed as driveline 200. The electric energy storage device 275 may be a battery, a capacitor, or an inductor. The downstream side of the DISG 240 is mechanically coupled to the drive gear 285 of the torque converter 206 via a shaft 241. The upstream side of the DISG 240 is mechanically coupled to the disconnect clutch 236. The torque converter 206 includes a turbine 286 to output torque to the input shaft 270. The input shaft 270 mechanically couples the torque converter 206 to an automatic transmission 208. The torque converter 206 may include a power take-off (PTO) 251 that may direct the torque of the powertrain to an external or additional mechanical load 252. The PTO 251 may be located on the drive wheel side of the torque converter or on the turbine side of the torque converter. In some examples, the PTO may be included in the automatic transmission 208. The PTO 251 may also include a reverse gear 287.The torque converter 206 also includes a torque converter (TCC) bypass clutch 212. Torque is transferred from the drive wheel 285 directly to the turbine 286 when the TCC is engaged. The TCC is electrically operated by the controller 12. Alternatively, the TCC may be hydraulically engaged. In one example, the torque converter may be referred to as a component of the transmission. The turbine speed and position of the torque converter may be determined via position sensor 239. In some examples, 238 and / or 239 may be torque sensors or may be combination position and torque sensors.When the torque converter bypass clutch 212 is fully disengaged, the torque converter 206 transfers engine torque to the automatic transmission 208 via fluid transfer between the torque converter turbine 286 and the torque converter drive wheel 285, thereby enabling torque multiplication. In contrast, when the torque converter bypass clutch 212 is fully engaged, engine output torque is directly transferred to an input shaft 270 of the transmission 208 via the torque converter clutch. Alternatively, the torque converter lock-up clutch 212 may be partially engaged, thereby allowing the amount of torque directly transferred to the transmission to be adjusted. The controller 12 may be configured to adjust the amount of torque transferred through the torque converter 212 by adjusting the torque converter lock-up clutch in response to various engine operating conditions or based on a driver-based engine operating request.The mechanical load 252 may be a hydraulic pump that operates a snow plow jack or a cement mixer. Alternatively, the mechanical load 252 may be a rotating mechanical device. The mechanical load controller 253 may be in communication with the controller 12 via a communication link 291 to provide position, speed, and torque information via the mechanical load sensors 254 252. The sensors 254 provide the position and speed information to the mechanical load controller 253 which, in turn, may forward the information to the controller 12 so that the PTO may be controlled.Automatic transmission 208 includes the gear clutches (e.g., gears 1- 6) 211 and a forward clutch 210. The gear clutches 211 and the forward clutch 210 may be selectively engaged to propel a vehicle. The torque output from the automatic transmission 208 may in turn be relayed to the rear wheels 216 to propel the vehicle via an output shaft 260. Specifically, the automatic transmission 208 may transmit an input driving torque to the input shaft 270 in response to a running state of the vehicle before transmitting an output driving torque to the rear wheels 216. Torque may also be directed to front wheels 217 via transfer case 261.Further, by activating the wheel brakes 218, a frictional force may be applied to the wheels 216. In one example, the wheel brakes 218 may be activated in response to the driver pressing his foot on a brake pedal (not shown). In further examples, controller 12 or a controller connected to controller 12 may apply the activated wheel brakes. In the same way, frictional force on wheels 216 may be reduced by releasing wheel brakes 218 in response to the driver releasing his foot from the brake pedal. Further, the vehicle brakes may apply a frictional force to the wheels 216 via the controller 12 as part of an automated engine stop procedure.A mechanical oil pump 214 may be in fluid communication with the automatic transmission 208 to provide hydraulic pressure to engage the various clutches, such as the forward clutch 210, the gear clutches 211, and / or the torque converter lock-up clutch 212. Mechanical oil pump 214 may be operated in accordance with torque converter 206 and may be driven, e.g., by rotation of the engine or DISG via input shaft 241. As a result, hydraulic pressure generated in mechanical oil pump 214 may increase as an engine speed and / or a DISG speed increase, while it may decrease as an engine speed and / or a DISG speed decrease.The controller 12 may be configured to receive the inputs from the engine 10, as shown in more detail in FIG. 1, and accordingly control an engine torque output and / or operation of the torque converter, transmission, DISG, clutches, and / or brakes. As one example, engine torque output may be controlled by adjusting a combination of spark timing, fuel pulse width, timing of fuel pulses and / or air charge, controlling throttle opening and / or timing, valve lift, and boost for turbo-charged engines or boosted engines. In the case of a diesel engine, controller 12 may control the engine torque output by controlling a combination of the fuel pulse width, the timing of the fuel pulses, and the air charge. In all cases, engine control may be performed on a cylinder-by-cylinder basis to control engine torque output. Controller 12 may also control torque output and electrical energy generation from the DISG by adjusting current flowing from or to the field and / or armature windings of the DISG as is known in the art. Controller 12 also receives road grade input information from inclinometer 281.When the idle stop conditions are met, the controller 42 may initiate engine shutdown by shutting off fuel and spark to the engine. However, in some examples, the engine may continue to rotate. Further, to maintain an amount of torsion in the transmission, the controller 12 may ground the rotating elements of the transmission 208 to a housing 259 of the transmission and thereby to the frame of the vehicle. More specifically, the controller 12 may engage one or more transmission clutches, such as the forward clutch 210, and engage the engaged transmission clutch(s) on the transmission housing 259 and the vehicle frame, as described in U.S. patent application Ser. No. 12 / 833,788, "METHOD FOR CONTROLLING AN ENGINE THAT MAY BE AUTOMATICALLY STOPPED," which is hereby incorporated by reference for all purposes and purposes. A transmission clutch pressure may be varied (e.g., increased) to adjust the engagement state of a transmission clutch and provide a desired amount of transmission torsion.A wheel brake pressure may also be adjusted during engine shutdown based on the transmission clutch pressure to assist in shutting down the transmission while reducing torque transmitted through the wheels. Specifically, by applying the wheel brakes 218 while engaging one or more engaged transmission clutches, counter forces may be applied to the transmission and thus to the driveline, thereby maintaining the transmission gears in active engagement and the potential torsional energy in the gear train of the transmission without moving the wheels. In one example, the wheel brake pressure may be adjusted to coordinate application of the wheel brakes with engagement of the engaged transmission clutch during engine shutdown. As such, the amount of torsion maintained in the transmission when the engine is off may be adjusted by adjusting the wheel brake pressure and the clutch pressure.When the restart conditions are met and / or an operator of the vehicle wishes to launch the vehicle, the controller 12 may reactivate the engine by resuming cylinder combustion. As further elaborated with reference to FIGS. 4-9, the engine may be started in various ways.Referring now to FIG. 3, a second example of a powertrain configuration of a vehicle is shown. The elements in driveline 300 having the same reference numerals as the elements in FIG. 2 are equivalent elements and operate as described in FIG. 2. Therefore, for the sake of brevity, the description of the elements common between FIGS. 2 and 3 is omitted. The description of FIG. 3 is limited to the elements other than the elements of FIG. 2.Driveline 300 includes dual clutch dual countershaft transmission 308. The transmission 308 is essentially an automatically operated manual transmission. The controller 12 actuates a first clutch 310, a second clutch 314, and a shift mechanism 315 to shift between gears (e.g., 1-5. Gear) 317. The first clutch 310 and the second clutch 314 may be selectively opened and closed to shift between gears 317. The output shaft 260 supplies the torque from the transmission 308 to the wheels 216.Referring now to FIG. 4, a flowchart of an example method for controlling a driveline of a hybrid vehicle is shown. The method of FIG. 4 may be stored as executable instructions in non-transitory memory of controller 12 shown in the systems of FIGS. 1-3.At 401, method 400 determines operating conditions of the vehicle. Operating conditions of the vehicle may include, but are not limited to, vehicle speed, brake pedal position, engine speed, engine load, 4×4 selection mode, 4×2 selection mode, vehicle chassis information (e.g., vertical wheel movement, yaw, pitch, and roll), and roadway slope. Method 400 continues at 402 after the operating conditions of the vehicle have been determined.At 402, method 400 judges whether or not a PTO operation request has been received. A PTO operation request may be executed by a driver of the vehicle or an external controller in communication with the powertrain controller 12 shown in FIGS. 1-3. A PTO operation request indicates that it is desired that an external load receive power from the engine 10 and / or the electric work machine 240. If method 400 judges that a PTO operation request has been executed, the answer is yes and method 400 proceeds to 412 of FIG. 5. Otherwise, the answer is no and method 400 proceeds to 403.Referring now to FIG. 5, at 412, method 400 judges whether the PTO operation request is for a stationary mode where the vehicle is parked or in a non-stationary mode where the vehicle may be moving. The stationary mode may be useful for external loads that do not need to move. In the steady-state mode, the PTO speed may be requested to be a fixed speed (e.g., 540 U / min) input via control commands from an external load device (e.g., a hydraulic pump controller) or a driver while the vehicle is stopped and / or parked. In the non-steady-state mode, the PTO speed may change with engine / motor speed and vehicle speed. Thus, the torque may be provided to the PTO and a driving force may be provided to the vehicle. If method 400 judges that steady state mode is requested, the answer is yes and method 400 proceeds to 413. Otherwise, the answer is no and method 400 proceeds to 424.At 413, method 400 judges whether the DISG-only or all electric machine PTO mode is selected. In the DISG-PTO-only mode, PTO torque is supplied via only the DISG and not via the engine. Such operation allows the PTO to operate in the reverse and forward directions. If method 400 judges that DISG-PTO only mode is selected, the answer is yes and method 400 proceeds to 414. Otherwise, the answer is no and method 400 proceeds to 434 of FIG. 6.At 434, method 400 closes driveline disconnect clutch such that the engine and DISG are mechanically coupled together. The engine or DISG may be selectively deactivated while driveline disconnect clutch is closed. Method 400 proceeds 435 after the disconnect clutch has been closed.At 435, method 400 judges whether or not engine output is above or alternatively within a threshold torque range of a threshold torque level. If the engine output torque is within or above a threshold torque, the answer is yes and method 400 proceeds to 437. Otherwise, the answer is no and method 400 proceeds to 436. For example, if the engine torque is 100 Nm, the threshold torque range is 10 Nm, and the threshold torque is 108 Nm, then the answer is yes and method 400 proceeds to 437.At 437, method 400 adjusts the engine torque and the DISG torque to provide the desired PTO speed. In one example, the engine load is set to a threshold level (e.g., 90 percent of the maximum engine torque) and then the DISG output torque is increased to a level at which the desired PTO speed is provided. If the DISG output torque is at a maximum level and the PTO speed is less than the desired PTO speed, engine torque may be increased to a maximum level at the current PTO speed. Method 400 continues at 404 of FIG. 4 after engine and DISG torque have been adjusted.In further examples, while the battery state of charge is greater than a threshold level, the DISG may output torque at a threshold before the engine is activated. Further, the engine may charge the vehicle batteries and provide electrical power to the vehicle's electrical grid while the PTO is in a steady state mode and the PTO torque requests are less than the available engine output torque. Thus, the engine may drive the PTO load while the DISG is converting engine torque to electricity to charge the vehicle batteries.At 436, method 400 adjusts engine torque to provide the desired PTO speed while the DISG is deactivated. Alternatively, at 436, the DISG may be in a generation mode and may supply current to vehicle batteries. The PTO speed may be maintained by the controller 12 determining an error between the target PTO speed and the actual PTO speed. If the actual PTO speed is less than the desired PTO speed, the engine throttle may be opened further to increase engine torque and thereby increase PTO speed. If the actual PTO speed is greater than the desired PTO speed, engine torque may be decreased via at least one of a plurality of actuators (e.g., throttle, cam timing, wastegate, fuel injectors, spark timing, etc.), thereby decreasing PTO speed. Method 400 proceeds to 404 of FIG. 4 after engine torque has been adjusted.In FIG. 5, at 414, method 400 judges whether or not the battery state of charge (battery SOC) is greater than a threshold charge level. In one example, the threshold state of charge may be estimated via measuring the battery voltage. If the battery charge is greater than a threshold level, the answer is yes and method 400 proceeds to 417. Otherwise, the answer is no and method 400 proceeds to 415. In one example, the threshold state of charge is a minimum charge level at which battery degradation does not occur.At 415, method 400 indicates an impending shutdown of the DISG. A shutdown of the DISG may be indicated via a light, display panel, or audible actuator. The indication of an imminent shutdown may be provided at a battery state of charge that is above the threshold charge level mentioned at 414. Alternatively, the engine may be automatically started when the battery charge is decreased to a threshold level and the PTO continues to operate.At 416, method 400 exits to provide torque to the PTO via the DISG. The DISG torque may be gradually decreased in a controlled manner to avoid a rapid change in PTO torque. Method 400 proceeds to 404 of FIG. 4.At 417, method 400 opens driveline disconnect clutch. Opening the driveline disconnect clutch mechanically decouples the engine from the DISG. As a result, the DISG may direct torque to the PTO without having losses due to spinning an engine not combusting air-fuel mixtures. Because the PTO is in a steady state mode, most of the torque provided by the DISG is transferred to the PTO. Method 400 continues at 418 after the disconnect clutch has been opened.At 418, method 400 exchanges control signals with a controller (e.g., 253 of FIG. 2 ) of the mechanical load. The mechanical load controller may control the PTO and the engine to provide a desired PTO output. Alternatively, the mechanical load controller may receive instructions from a powertrain controller and provide the control signals from the sensors to the powertrain controller. The example signals exchanged between the mechanical load controller and the powertrain controller include, but are not limited to, PTO speed, PTO device position (e.g., a position of an actuator such as a ball screw), a PTO engagement signal, a PTO disengagement signal, a PTO device end of motion, a PTO rotational direction, and a PTO stop signal. Method 400 continues at 419 after the signals are exchanged between the mechanical load controller and the powertrain controller.At 419, method 400 judges whether or not the PTO reverse rotation is requested. The PTO reverse rotation may be requested by an operator or a controller such as the mechanical load controller. If method 400 judges that there is a request for reverse rotation, the answer is yes and method 400 proceeds to 420. If method 400 judges that there is no request for reverse rotation, the answer is no, the PTO is rotating in a forward direction, and method 400 proceeds to 421.At 420, the DISG is rotated so that the PTO rotates in a reverse direction. The DISG reverse rotation may be provided via a reverse gear included in the PTO device. The reverse gear may be selectively engaged. Alternatively, the DISG may be rotated in a reverse direction such that the PTO rotates in a reverse direction without a reverse gear. DISG reverse rotation may be provided via electrical commutation, or alternatively in some configurations by reversing the polarity of power applied to the DISG.At 421, method 400 operates the DISG and PTO at the desired speed. In one example, the DISG speed is controlled in accordance with the actual PTO speed. For example, the actual PTO speed may be subtracted from the desired PTO speed to provide a PTO speed error. The current supplied to the DISG may then be adjusted to adjust the DISG torque to provide a zero error between the actual PTO speed and the desired PTO speed. If the actual PTO speed is less than the target PTO speed, the DISG current may be increased. Alternatively, depending on the DISG design, the frequency of power supplied to the DISG may be adjusted to adjust DISG torque. Method 400 proceeds to 422 after the DISG speed is adjusted to provide the desired PTO speed.At 422, method 400 judges if a PTO-powered device is on a boundary. In one example, the PTO-operated device may be a ball screw having start and end of motion limit switches. If the PTO operated device is at a travel limit, the answer is yes and method 400 proceeds to 423. Otherwise, the answer is no and method 400 proceeds to 404 of FIG. 4.At 423, method 400 stops DISG and PTO rotation. The DISG and PTO rotation may be gradually decreased at a predetermined rate as the PTO operated device reaches a boundary state. The DISG may be restarted via operator or controller input in an opposite direction. In this way, the DISG may be operated with the PTO such that the PTO operated device moves between two boundary positions. Method 400 continues at 404 of FIG. 4 after the DISG rotation has been completed.At 424, the method judges whether or not the battery state of charge is greater than a threshold state of charge. If the battery state of charge is greater than the threshold level, the answer is yes and method 400 proceeds to 427. Otherwise, the answer is no and method 400 proceeds to 425. The threshold state of charge helps ensure that sufficient power can be provided to the DISG to continue rotating the PTO.At 425, method 400 activates the engine if the engine has been stopped. The engine may be activated by starting the engine. In one example, the engine may be started by supplying air, spark, and fuel to the engine while the disconnect clutch is engaged with the rotating DISG. Method 400 continues at 426 after the engine is activated.At 426, method 400 stops providing positive torque (e.g., a torque to rotate the driveline) via the DISG. However, the DISG may provide electrical energy to vehicle batteries via converting driveline rotational energy to electrical energy. Method 400 continues at 427 after the positive torque output of the DISG is decreased.At 427, method 400 judges if the DISG may provide the desired amount of wheel torque plus an additional predetermined amount of torque to rotate the PTO. In one example, 25% of the available DISG torque is reserved for PTO operation. For example, if the DISG has a 100 Nm torque output capacity at speeds below its base speed, 75 Nm of DISG torque may be provided to generate wheel torque. The remaining 25 Nm are reserved for providing the PTO torque. However, if the desired wheel torque is low, the PTO may receive up to 75% of the available DISG output torque. The desired wheel torque may be determined by entering the accelerator pedal position into a lookup function or table that converts the pedal position into a desired drive wheel, turbine, transmission output, or wheel torque. The desired torque is then compared to the torque available via the DISG. The available DISG torque may be stored in memory in a look-up table indexed via battery state of charge and DISG speed. If the available DISG torque is greater than the DISG torque producing the desired torque, the answer is yes and method 400 proceeds to 432. Otherwise, the answer is no and method 400 proceeds to 428. It should be noted that the target torque may be converted to a DISG target torque by appropriately considering transmission gear ratios and transmission losses depending on the shape of the target torque.At 428, method 400 closes the disconnect clutch. The disconnect clutch is closed so that torque provided by the DISG may be boosted by engine torque. Further, the engine is started if it is not already running. In this way, the torque provided by the DISG may be combined with engine torque to provide the desired wheel torque while the PTO is operating and the vehicle is moving. Method 400 continues at 429 after the disconnect clutch has been closed and the engine has been started.At 429, method 400 judges whether or not the engine alone has torque capacity without the DISG providing positive torque to the driveline to provide the desired wheel torque plus an additional predetermined amount of torque to rotate the PTO. In one example, the desired wheel torque may be converted to a desired engine torque via accounting for transmission ratio and losses. In one example, 25% of the available engine torque is reserved for PTO operation. For example, if the engine has a 200 Nm torque output capacity at a particular speed, 150 Nm of engine torque may be provided to generate the wheel torque. The remaining 50 Nm are reserved for providing the PTO torque. However, if the desired wheel torque is low, the PTO may receive up to 75% of the available engine output torque. In one example, the desired wheel torque is compared to the torque available via the engine. The available engine torque may be stored in memory in a look-up table indexed by engine speed and adjusted for ambient air density, or calculated based on a model of maximum engine torque at the current conditions and hardware capability in real-time. If the available engine torque is greater than the engine torque that generates the desired wheel torque, the answer is yes and method 400 proceeds to 430. Otherwise, the answer is no and method 400 proceeds to 431. It should be noted that the desired wheel torque may be converted to a desired engine torque by considering transmission gear ratios and transmission losses.At 430, method 400 adjusts engine torque to provide the desired wheel torque while the PTO is driving an external device. Because the amount of engine torque transferred to the PTO may not be known in some examples, the torque provided to the PTO may be determined and added to the desired engine torque such that the desired wheel torque is provided. In one example, the torque provided to the PTO may be determined from the equation: where T wheel is the desired wheel torque, T eng is the desired engine torque, T pto is the PTO torque, Tc mult is the torque converter multiplication ratio, Tgear_ratiosis the current transmission gear ratio, Taxle_ratiois the axis ratio, T driveline_losses is a multiplier reflecting driveline losses, and F Grade is a multiplier accounting for road grade determined via an inclinometer. The desired engine torque may be estimated via a map of engine torque indexed by engine speed and load. The wheel torque may be determined from the equation:. The torque converter torque multiplication ratio, the ratio, the axis ratio, and the driveline torque loss multiplier may be empirically determined based on engine speed, vehicle speed, the selected ratio, and other factors and retrieved from memory. The vehicle inertia may be adjusted for a changing vehicle mass.If the estimated wheel torque is less than desired, the desired engine torque may be increased via adjusting the engine torque to increase the actual wheel torque to the desired wheel torque. In this way, engine torque may be increased to provide the desired wheel torque even when the amount of torque consumed by the PTO is unknown. Method 400 proceeds to 404 of FIG. 4.At 431, method 400 adjusts the engine torque and the DISG torque to provide the desired wheel torque while the PTO is driving an external device. In one example, the engine is operated at an efficient operating condition based on the vehicle speed and the selected gear of the transmission. If the desired wheel torque is not available at the operating condition, the DISG output torque is increased to provide the desired wheel torque. If the DISG does not have the capacity to provide the desired wheel torque in the presence of a PTO load, engine operation is adjusted to increase engine torque output at a lower fuel economy operating condition. The DISG torque is increased via increasing current supplied to the DISG. Engine torque is adjusted via adjusting throttle position, wastegate position, cam timing, fuel amount, and spark timing. In one example, the wheel torque may be determined in accordance with the following equation when the DISG is providing torque to the driveline: where T DISG is the amount of torque provided to the driveline via the DISG, and the remaining variables are as described above. Thus, the engine torque and the DISG torque may be adjusted to provide the desired wheel torque in the presence of a PTO load. Method 400 continues at 404 of FIG. 4 after engine torque and DISG torque have been adjusted.At 432, the disconnect clutch is opened and the engine is stopped. The disconnect clutch is opened so that the DISG does not need to rotate the deactivated engine. The engine is deactivated to conserve fuel. Method 400 continues at 433 after the disconnect clutch has been opened.At 433, method 400 adjusts the DISG torque via adjusting current supplied to the DISG. In one example, the DISG torque is adjusted to provide the desired wheel torque while the PTO is operating passively. For example, if 15 Nm of wheel torque is desired and the PTO consumes 5 Nm, the DISG torque is set to 20 Nm by increasing the DISG torque until the vehicle accelerates at a rate expected when 15 Nm of wheel torque is present.In FIG. 4, at 403, method 400 recharges the batteries via the DISG, which converts rotational energy from the engine or vehicle kinetic energy to electrical energy. In some examples, after PTO operation, charging of the batteries may be delayed until the vehicle is in a deceleration state or is travelling down a hill where the kinetic energy of the vehicle may be converted to electrical energy without combusting an air-fuel mixture to provide the electrical energy. In further examples, the batteries may be charged to a threshold level via converting engine rotational energy to electrical energy. Once the batteries reach the threshold level, any additional charging of the batteries may be solely from the kinetic energy of the vehicle. Method 400 continues at 404 after charging of the batteries has been initiated.At 404, method 400 judges if there is a request for 4×4 mode (e.g., four wheel drive mode). A request for the 4×4 mode may be executed by a driver or an external controller (e.g., a controller sensing wheel slip). If method 400 judges that a request for 4×4 mode is present, the answer is yes and method 400 proceeds to 407. Otherwise, the answer is no and method 400 proceeds to 405. In some examples, method 400 automatically starts a stopped engine when the driver selects a high or low gear in the four-wheel drive range while the vehicle is in a two-wheel drive mode.At 405, method 400 judges whether or not there are degraded (e.g., rough, rich (the frequency of curves of the road), smooth, or obstructed) road conditions. In one example, a rough road may be determined from a distance of vertical motion and the frequency of vertical motion of the vehicle wheels. Smooth roads may be determined by an amount of wheel slip. An object blocking a road in front of the vehicle may be detected via an optical, sound or radar sensing device. If a rough, curved, smooth, or obstructed road is present, the answer is yes and method 400 proceeds to 450 of FIG. 7. Otherwise, the answer is no and method 400 proceeds to 406.At 406, method 400 operates the driveline engine and disconnect clutch in accordance with the two-wheel drive automated base modes. During two-wheel drive modes, the DISG may be selectively coupled to the engine via the disconnect clutch of the vehicle to provide wheel torque and charge vehicle batteries and provide electrical power to the vehicle's electrical grid. In one example, during vehicle acceleration, the DISG provides torque to the driveline of the vehicle while the battery SOC is above a threshold SOC. Further, during vehicle deceleration and downhill conditions, the DISG provides electrical energy to vehicle batteries. Method 400 returns to 401 after the engine and DISG are operated in accordance with the conditions of the base two wheel drive mode.Referring now to FIG. 7, at 450, method 400 judges whether or not an approach speed (e.g., a speed at which the vehicle approaches an object) is faster (e.g., a shorter period of time between the contact between the vehicle and the object) than a first threshold approach speed or whether a degraded road condition metric (e.g., a curved, smooth, or rough road condition) (e.g., a number representing a curved, smooth, or rough road condition) is greater than a first threshold amount of the road condition metric. In other words, the method 400 judges whether or not there is a higher level of road roughness, curvature of road, road smoothness, or a high speed of approach to an object. If method 400 judges that a road condition metric is greater than a first road condition threshold parameter or if the vehicle approach speed is faster than a first threshold vehicle approach speed, the answer is yes and method 400 proceeds to 451. Otherwise, the answer is no and method 400 proceeds to 454.At 451, method 400 exits from automatically stopping the engine and engine idle ready mode. The engine idle ready mode is a mode in which the engine is allowed to idle while the driveline disconnect clutch is in an open state and while the DISG is providing torque to the driveline. For example, method 400 may prevent automatic engine stopping during vehicle deceleration or when the vehicle is stopped. Automatically stopping the engine is an engine stop initiated by a controller based on inputs without providing a specific engine stop request by a driver input having a single purpose of stopping and / or starting the engine. By ending automatic engine stopping, the powertrain may be in a state more suitable for responding to the road and vehicle conditions. For example, full driveline torque is available (e.g., via the engine and the DISG) so that the vehicle may overcome undesirable conditions and accelerate in the absence of the undesirable conditions. Further, at 451, the driveline disconnect clutch is maintained closed or closed so that the engine and DISG are rotating at the same speed. Method 400 continues at 452 after the automatic stopping of engine rotation has ended.At 452, method 400 judges whether or not the engine has currently stopped rotation. It may be judged that the engine has stopped rotation when the engine speed is zero. If method 400 judges that the engine has stopped rotation, the answer is yes and method 400 proceeds to 453. Otherwise, the answer is no and method 400 proceeds to 454.At 453, method 400 restarts the engine to make it ready for any action that the driver may take. Engine rotation may be started via driveline disconnect clutch closing and supplying spark and fuel to the engine. Method 400 continues at 454 after the engine has been restarted.At 454, method 400 judges whether or not the approach speed is slower than the first threshold approach speed and faster than a second threshold approach speed, or whether a road condition metric (e.g., a smooth or rough road condition) is less than the first road condition threshold parameter and greater than a second road condition threshold parameter. The second threshold approach speed is lower than the first threshold approach speed. The second threshold road condition is lower than the first threshold road conditions. In other words, the method 400 judges whether or not there is a medium-higher level of road roughness, curvature of road, road smoothness, or medium-high approach speed to an object. If method 400 judges that the road condition is less than the first threshold road condition and greater than the second threshold road condition, or if the approach of the vehicle is less than the first threshold approach speed of the vehicle and greater than the second threshold approach speed of the vehicle, the answer is yes and method 400 proceeds to 455. Otherwise, the answer is no and method 400 proceeds to 458.At 455, method 400 allows for automatic engine output reduction to an engine idle ready mode via driveline disconnect clutch opening during low wheel torque request conditions, but where automatic engine rotation stopping is not allowed. For example, at low desired wheel torques, the engine may be decoupled from the DISG, and then engine speed is decreased to an idle speed. Torque may be provided to the driveline via the DISG. If the wheel torque request increases, the engine speed is increased to the DISG speed, then the driveline disconnect clutch is closed. In this way, method 400 increases the standby state of the vehicle during some conditions, but allows fuel to be saved by allowing the engine to idle instead of rotating synchronously with the DISG when the vehicle is in 4×2 operating mode. Method 400 continues at 456 after the automatic stop conditions are revised.At 456, method 400 judges whether or not engine rotation is currently stopped. It may be judged that the rotation of the engine is stopped when the engine speed is zero. If method 400 judges that engine rotation is stopped, the answer is yes and method 400 proceeds to 457. Otherwise, the answer is no and method 400 proceeds to 458.At 457, method 400 restarts the engine to make it ready for any action the driver may take. The engine may be started via closing the driveline disconnect clutch and supplying spark and fuel to the engine. Method 400 continues at 458 after the engine is restarted.At 458, method 400 judges whether an approach speed is slower than the second threshold approach speed and faster than a third threshold approach speed or whether a road condition metric (e.g., a smooth or rough road condition) is less than the second road condition threshold parameter and greater than a third road condition threshold parameter. The third threshold approach speed is slower (e.g., a longer period of time between contact between the vehicle and the object) than the second threshold approach speed. The third road condition threshold parameter is lower than the second road condition threshold parameter. In other words, the method 400 judges whether or not there is an average level of road roughness, curvature of road, road smoothness, or an average approach speed to an object. If method 400 judges that a road condition metric is less than the second road condition threshold parameter and greater than the third road condition threshold parameter, or if the approach of the vehicle is slower than the second threshold approach speed of the vehicle and faster than the third threshold approach speed of the vehicle, the answer is yes and method 400 proceeds to 459. Otherwise, the answer is no and method 400 proceeds to 464 of FIG. 8.At 459, method 400 allows engine rotation to be automatically stopped to an engine speed of zero. Engine speed may be decreased to zero by opening the driveline disconnect clutch and ceasing fuel flow to the engine when the vehicle wheel torque request is low. The DISG may further provide torque to the driveline of the vehicle to propel the vehicle. In this way, method 400 allows for further fuel consumption reduction when the vehicle is in a two-wheel drive mode rather than a four-wheel drive mode. Method 400 continues at 464 of FIG. 8 after the engine automatic stop conditions have been revised.It should be noted that method 400 may replace the approach speed greater than a first, second, or third threshold, if desired, at 440, 444, 448, 450, 454, and 458 with an approach distance less than a first, second, or third threshold. Alternatively, at 440, 444, 448, 450, 454, and 458, the method 400 may judge whether or not an approach speed is greater than a first, a second, or a third threshold and whether or not an approach distance is less than a first, a second, or a third threshold.Referring now to FIG. 8, at 464, it is judged whether or not an approach speed is slower than the third threshold approach speed or whether a road condition metric (e.g., a number representing a curved, smooth, or rough road condition) is less than the third road condition threshold parameter. In other words, the method 400 judges whether or not there is a lower level of road roughness, curvature of road, road smoothness, or a lower approach speed to an object. If method 400 judges that a road condition metric is less than the third road condition threshold parameter, or if the vehicle approach is slower than the third vehicle approach speed threshold parameter, the answer is yes and method 400 proceeds to 465. Otherwise, the answer is no and method 400 returns at 401 to FIG. 4.At 465, method 400 allows for automatically stopping rotation of the engine to an engine speed of zero. Engine speed may be decreased to zero by opening the driveline disconnect clutch and ceasing fuel flow to the engine when the vehicle wheel torque request is low. If the wheel torque request increases, the engine may be restarted via the DISG or starter and driveline disconnect clutch may be closed so that driveline and wheel torque are increased. The DISG may continue to provide torque to the driveline of the vehicle to propel the vehicle while being decoupled from the engine. Method 400 returns to 401 of FIG. 4 after the engine automatic stop conditions have been revised.In FIG. 4, at 407, method 400 judges whether or not more encumbered (e.g., rough, curvey, smooth, or obstructed) road conditions are present. The road conditions and obstacles may be determined as described at 405. If a rough, cornering, smooth, or congested road is present, the answer is yes and method 400 proceeds to 440 of FIG. 7. Otherwise, the answer is no and method 400 proceeds to 408.Referring now to FIG. 7, at 440, method 400 judges whether or not an approach speed (e.g., a speed at which the vehicle approaches an object) is faster (e.g., a shorter period of time between the contact between the vehicle and the object) than a first threshold approach speed or whether a road condition metric (e.g., a curved, smooth, or rough road condition) is greater than a first road condition metric threshold amount. In other words, the method 400 judges whether or not there is a higher level of road roughness, curvature of road, road smoothness, or a higher approach speed to an object. If method 400 judges that a road condition metric is greater than a first road condition threshold parameter, or if the vehicle approach speed is faster than a first threshold vehicle approach speed, the answer is yes and method 400 proceeds to 441. Otherwise, the answer is no and method 400 proceeds to 444.The first to third threshold road conditions mentioned between 440 and 448 may be the same as or different from the first to third threshold road conditions mentioned between 450 and 458. Accordingly, the first to third threshold approach speeds mentioned between 440 and 448 may be the same as or different from the first to third threshold approach speeds mentioned between 450 and 458.At 441, method 400 exits from automatically stopping the engine. For example, method 400 inhibits automatic engine stopping during vehicle deceleration or when the vehicle is stopped. Automatic engine stopping is an engine stop initiated by a controller based on inputs without a specific engine stop request provided by a driver input having a single purpose of stopping and / or starting the engine. By ending automatic engine stopping, the powertrain may be in a state more suitable to respond to the road and vehicle conditions. For example, if full driveline torque is available (e.g., via the engine and the DISG), the vehicle may overcome undesirable conditions and accelerate in the absence of the undesirable conditions. Further, at 441, the driveline disconnect clutch is maintained closed or closed so that the engine and DISG are rotating at the same speed. Method 400 continues at 442 after the automatic stopping of engine rotation has ended.At 442, method 400 judges whether or not the engine has currently stopped rotation. It may be judged that the engine has stopped rotation when the engine speed is zero. If method 400 judges that the engine has stopped rotation, the answer is yes and method 400 proceeds to 443. Otherwise, the answer is no and method 400 proceeds to 444.At 443, method 400 restarts the engine to make it ready for any action that the driver may take. Engine rotation may be started via driveline disconnect clutch closing and supplying spark and fuel to the engine. Method 400 continues at 444 after the engine has been restarted.At 444, method 400 judges whether or not the approach speed is slower than the first threshold approach speed and faster than a second threshold approach speed, or whether a road condition metric (e.g., a smooth, curved, or rough road condition) is less than the first road condition threshold parameter and greater than a second road condition threshold parameter. The second threshold approach speed is lower than the first threshold approach speed. The second threshold road condition is lower than the first threshold road conditions. In other words, the method 400 judges whether or not there is a medium-higher level of road roughness, curvature of road, road smoothness, or medium-high approach speed to an object. If method 400 judges that the road condition is less than the first threshold road condition and greater than the second threshold road condition, or if the approach of the vehicle is less than the first threshold approach speed of the vehicle and greater than the second threshold approach speed of the vehicle, the answer is yes and method 400 proceeds to 445. Otherwise, the answer is no and method 400 proceeds to 448.At 445, method 400 allows for automatic engine output reduction to engine idle conditions via driveline disconnect clutch opening during low wheel torque request conditions, but where automatic engine rotation stopping is not allowed. For example, at low desired wheel torques, the engine may be decoupled from the DISG and then engine speed is decreased to an idle speed. Torque may be provided to the driveline via the DISG. If the wheel torque request increases, the engine speed is increased to the DISG speed and then driveline disconnect clutch is closed. In this way, method 400 increases the standby state of the vehicle during some conditions, but allows fuel to be saved by allowing the engine to idle instead of rotating synchronously with the DISG when the vehicle is in 4×4 operating mode. Method 400 continues at 446 after the automatic stop conditions have been revised.At 446, method 400 judges whether or not engine rotation is currently stopped. It may be judged that the rotation of the engine is stopped when the engine speed is zero. If method 400 judges that engine rotation is stopped, the answer is yes and method 400 proceeds to 447. Otherwise, the answer is no and method 400 proceeds to 448.At 447, method 400 restarts the engine to make it ready for any action the driver may take. The engine may be started via closing the driveline disconnect clutch and supplying spark and fuel to the engine. Method 400 continues at 448 after the engine is restarted.At 448, method 400 judges whether or not an approach speed is slower than the second threshold approach speed and faster than a third threshold approach speed, or whether a road condition metric (e.g., a smooth or rough road condition) is less than the second road condition threshold parameter and greater than a third road condition threshold parameter. The third threshold approach speed is slower (e.g., a longer period of time between contact between the vehicle and the object) than the second threshold approach speed. The third road condition threshold parameter is lower than the second road condition threshold parameter. In other words, the method 400 judges whether or not there is an average level of road roughness, curvature of road, road smoothness, or an average approach speed to an object. If method 400 judges that a road condition metric is less than the second road condition threshold parameter and greater than the third road condition threshold parameter, or if the approach of the vehicle is slower than the second threshold approach speed of the vehicle and faster than the third threshold approach speed of the vehicle, the answer is yes and method 400 proceeds to 449. Otherwise, the answer is no and method 400 proceeds to 460 of FIG. 8.At 449, during conditions of low wheel torque request via driveline disconnect clutch opening, method 400 allows engine output to be automatically decreased until engine idle conditions, but engine rotation is not automatically stopped. Thus, to respond to changing driver wheel torque commands that may be affected by the vehicle and road conditions, the powertrain standby state is higher in the four-wheel drive mode compared to when the vehicle is operated in the two-wheel drive mode. Method 400 continues at 460 of FIG. 8 after the engine automatic stop conditions have been revised.In FIG. 8, it is now judged whether or not the engine rotation has been stopped. If yes, the answer is yes and method 400 proceeds to 461. If no, the answer is no and method 400 proceeds to 461.At 461, the engine is restarted. The engine may be restarted by supplying spark and fuel to the engine and cranking the engine using the DISG or a separate starter. Method 400 continues at 462 after the engine is started.At 462, it is judged whether a speed of approach of the vehicle to an object is slower than the third threshold speed of approach or whether a road condition metric is less than the third road condition threshold parameter. In other words, the method 400 judges whether or not there is a lower level of road roughness, curvature of road, road smoothness, or a lower approach speed to an object. If method 400 judges that a road condition metric is less than the third road condition threshold parameter, or if the approach of the vehicle is slower than the third approach speed threshold parameter of the vehicle, the answer is yes and method 400 proceeds to 463. Otherwise, the answer is no and method 400 returns at 408 of FIG. 4.At 463, method 400 allows the engine to automatically stop rotating to an engine speed of zero. Engine speed may be decreased to zero by opening the driveline disconnect clutch and ceasing fuel flow to the engine when the vehicle wheel torque request is low. If the wheel torque request increases, the engine may be restarted via the DISG or starter and driveline disconnect clutch may be closed so that driveline and wheel torque are increased. The DISG may continue to provide torque to the driveline of the vehicle to propel the vehicle while being decoupled from the engine. Method 400 returns to 408 of FIG. 4 after the engine automatic stop conditions have been revised.In FIG. 4, it is now judged at 408 whether or not a request for a low mode of four-wheel drive (low 4×4 mode) is requested. The low mode of four-wheel drive may be selected by a driver or by a controller. If method 400 judges that the low four-wheel drive mode is selected, the answer is yes and method 400 proceeds to 466 of FIG. 9. Otherwise, the answer is no and method 400 proceeds to 409.Referring now to FIG. 9, method 400 sets engine start conditions to include restarting an engine that stopped rotation when a driver or controller releases a brake pedal or brake actuator. Further, the disconnect clutch is closed so that engine torque is provided to vehicle wheels. Thus, when the driveline is in the low range of four-wheel drive, the engine may be automatically started without a specific driver request to restart the engine via a dedicated input having a single function of starting and / or stopping the engine. Starting the engine upon brake release allows the driveline to increase wheel torque as compared to when only the DISG is providing torque to vehicle wheels. Method 400 continues at 467 after engine restart conditions have been adjusted to restart the engine upon brake release.At 467, method 400 commands the torque converter input command torque responsive to a different schedule from when the vehicle is operating in a high range of four-wheel drive or two-wheel drive mode. For example, the DISG and engine may contribute different amounts of torque to the drive wheel of the torque converter while the vehicle is operated in a low four wheel drive range compared to when the vehicle is operated in a two wheel drive or a high four wheel drive range. Specifically, during the low range of four wheel drive, the DISG may provide a higher percentage of wheel torque than the engine when the desired wheel torque is less than a threshold torque so that the vehicle may more evenly accelerate. In contrast, during the high range of four-wheel drive, the engine may provide a higher percentage of wheel torque than the DISG when the desired wheel torque is less than the same threshold torque.In addition, without the input from a driver operating a dedicated input having a single purpose of starting and / or stopping the engine rotation, the engine may be automatically started and stopped under other operating conditions when the vehicle is operated in the low range four-wheel drive compared to when the vehicle is operated in the low four-wheel drive mode. For example, the engine may be idling for a longer period of time after the vehicle stops moving while in the low four-wheel drive mode as compared to when the vehicle is operating in the two-wheel drive mode or in a high gear range of the four-wheel drive. Method 400 proceeds to 468 after the torque converter input torque schedule and engine running schedule have been adjusted for the low range of four wheel drive.At 468, method 400 commands a unique threshold battery state of charge at which the engine may be automatically stopped while the vehicle is operating in a low range of four-wheel drive. In one example, the engine may be stopped after the battery state of charge reaches a first battery charge threshold while the vehicle is operating in the low four-wheel drive range. On the other hand, the engine may be stopped after the battery state of charge reaches a second battery charge threshold, the second battery charge threshold being lower than the first battery charge threshold, when the vehicle is operating in two-wheel drive or in the high range of four-wheel drive. The engine may be automatically stopped after the battery state of charge reaches a higher level while the vehicle is in the low range of four-wheel drive, so that the number of times the disconnect clutch is engaged or disengaged may be reduced to reduce disconnect clutch degradation. If the vehicle is not operating in the low gear region of four-wheel drive, engine rotation may be stopped at a lower battery state of charge, so less fuel may be consumed to charge the batteries.Further, the driveline disconnect clutch may be closed and opened at 468 according to another schedule compared to when the vehicle is operating in a low four-wheel drive range and compared to when the vehicle is operating in a high four-wheel drive range or in a two-wheel drive mode. In one example, the driveline disconnect clutch is maintained in a closed state when the vehicle is operating in a low range of four-wheel drive, while the driveline disconnect clutch may be selectively opened when the vehicle is operating in a high range of four-wheel drive and during two-wheel drive. In another example, the driveline disconnect clutch may be opened after the vehicle is stopped for a first period of time while the vehicle is operating in the low four-wheel drive range. In contrast, the driveline disconnect clutch may be opened after the vehicle is stopped for a second period of time, the second period of time being less than the first period of time while the vehicle is operating in two-wheel drive or in the high range of four-wheel drive. Method 400 continues at 410 of FIG. 4 after the disconnect clutch and engine automatic stop schedules have been adjusted for the low four-wheel drive range.Referring now to FIG. 4, at 409, method 400 allows the DISG to propel the vehicle upon releasing the vehicle brake without starting the engine. Further, the DISG may propel and / or propel the vehicle until a threshold wheel torque request until battery SOC is lowered to a threshold level. By driving the vehicle with the DISG and without the engine, it is possible to allow the vehicle to creep at a low speed without a driver input torque request. The DISG may propel the vehicle to a threshold wheel torque level, and then the engine may be started so that the DISG and engine provide torque to the driveline at higher desired wheel torques requested. In further examples, the DISG and engine may drive the engine when releasing the vehicle brake depending on battery SOC. Method 400 continues at 410 after the DISG is allowed to propel the vehicle without the engine after releasing the brake pedal.At 410, method 400 judges whether or not manual control (e.g., control by the driver of the vehicle) of the engine, driveline disconnect clutch, and motor is requested. A manual request for control may be made via a display input or via a switch or other known user interface. If method 400 judges that manual control via the engine, driveline disconnect clutch, and motor is requested, the answer is yes and method 400 proceeds to 470 of FIG. 10.Otherwise, the answer is no and method 400 proceeds to 411.Referring now to FIG. 10, method 400 judges whether or not manual control via driveline disconnect clutch is requested at 470. In one example, method 400 may judge that manual control via the disconnect clutch is desired in response to a driver input. If method 400 judges that manual control via driveline disconnect clutch is requested or desired, the answer is yes and method 400 proceeds to 471. Otherwise, the answer is no and method 400 proceeds 473.At 471, method 400 judges whether or not the driver requests that the driveline disconnect clutch be engaged in a closed position. Method 400 may determine that driveline disconnect clutch is requested to be engaged in a closed position in response to user input from the driver. If method 400 judges that it is desired to engage the disconnect clutch in a closed position, the answer is yes and method 400 proceeds to 472. Otherwise, the answer is no and method 400 proceeds to 473. If method 400 proceeds to 400, the driveline disconnect clutch is automatically actuated, not in response to a specific driver request to open or close the driveline disconnect clutch.At 472, method 400 closes the driveline disconnect clutch and locks it in the closed state until the driver releases manual control via the driveline disconnect clutch. Closing the driveline disconnect clutch mechanically couples the engine to the DISG, but the DISG and / or engine may be deactivated when the driveline disconnect clutch is closed. Method 400 continues at 473 after the driveline disconnect clutch has been closed.At 473, method 400 judges whether or not DISG-only operation is requested. In the DISG-only operating mode, the engine is deactivated by stopping fuel flow to the engine. The engine throttle may also be closed with the cam timing / lift set at a lower volumetric efficiency when the engine is deactivated to increase pumping losses and decrease air flow through the engine. Alternatively, the throttle may be open and the cam timing / lift may be set to a higher volumetric efficiency to reduce engine pumping losses. The DISG-only operation may be manually selected by the driver. If the DISG-only mode is requested, the answer is yes and method 400 proceeds to 474. Otherwise, the answer is no and method 400 proceeds to 478.At 474, method 400 opens the driveline disconnect clutch to reduce spin losses and thereby increase the amount of energy available to propel the vehicle. If the driveline disconnect clutch has been manually closed, entry into DISG-only mode may be inhibited. Method 400 continues at 475 after the driveline disconnect clutch has been opened.At 475, method 400 judges whether or not the battery SOC is less than a threshold SOC. In one example, the threshold SOC is at a level that allows the engine to be restarted via the DISG or another starter. The battery SOC may be determined from the battery voltage. If method 400 judges that the battery SOC is less than a threshold SOC, the answer is yes and method 400 proceeds to 476. Otherwise, the answer is no and method 400 proceeds to 480.At 476, method 400 restarts the engine. The engine is restarted so that the DISG may change modes of providing positive torque to the driveline to absorb torque from the driveline and generating electrical energy to recharge the batteries. In further examples, the DISG may be simply shut down without starting the engine after the operator is provided an indication of an impending shut down of the DISG. Method 400 continues at 477 after the engine has been restarted.At 477, method 400 changes the DISG mode to a mode where electrical energy from the DISG is provided to the batteries. However, if the engine lacks torque to provide driver demanded torque, the driver is provided an indication that the DISG is not available. Otherwise, the engine provides torque based on the driver torque request and charging the battery via the DISG. Method 400 proceeds to 480 after the DISG mode is changed.At 478, the method judges if engine-only mode is manually requested by the driver. In engine-only mode, the driveline disconnect clutch is closed and the DISG does not provide positive torque to the driveline. However, in some examples, the DISG may provide negative torque to the driveline to recharge the batteries and provide electrical power to the vehicle's electrical grid. If the engine-only mode is manually requested by the driver, the answer is yes and method 400 proceeds to 479. Otherwise, the answer is no and method 400 proceeds to 480.At 479, method 400 disables DISG from providing positive torque to the driveline. However, in some examples, the DISG may convert rotational energy from the engine to electrical energy to charge vehicle batteries and provide electrical power to the vehicle's electrical grid. Method 400 continues at 480 after the DISG is deactivated.At 480, method 400 judges whether or not a request to enter a downhill drive mode has been requested. In some examples, at 480, an uphill drive mode may be provided instead of or in addition to the downhill drive mode. In a downhill drive mode, the engine and DISG may provide a higher level of vehicle braking than when the vehicle is not in a downhill drive mode. A request to enter a downhill travel mode may be manually input by the driver. Alternatively, the downhill travel mode may be entered when the inclinometer of the vehicle indicates a negative grade of the roadway that is steeper than a negative threshold grade. If a downhill mode request is requested, the answer is yes and method 400 proceeds to 481. Otherwise, the answer is no and method 400 proceeds to 482. In examples that include an uphill drive mode, the driveline disconnect clutch is actuated in a similar manner.At 481, method 400 closes the disconnect clutch to mechanically couple the engine to the DISG and vehicle braking via increased engine braking and DISG brakes is increased. In one example, engine braking is increased by adjusting the timing of the valves of the engine. DISG braking is increased by allowing more field current to be supplied to the DISG. In one example, the rate of DISG braking and engine braking is adjusted responsive to the slope of the roadway. For example, if it is assumed that the road surface is smoother than a threshold, the rate of DISG and engine braking may be decreased. Method 400 continues at 482 after DISG and engine braking has been adjusted.At 482, method 400 allows the driver to manually input engine stop conditions. Additionally, method 400 stops the engine in response to the manually input stop conditions. For example, the driver may input a time period after the vehicle reaches a speed of zero before engine rotation can be automatically stopped. In another example, the driver may specify a battery threshold SOC at which engine rotation may be automatically stopped. In yet another example, the driver may specify that the engine is not stopped when the rising or falling slope is steeper than a specified value. Method 400 continues at 483 after the driver is allowed to manually input the engine stop conditions and after the engine stop conditions are implemented.At 483, method 400 allows the driver to manually enter the conditions of the DISG operating mode. Further, the method 400 operates the DISG in response to the manually entered conditions. For example, the driver may input a level of the wheel torque request below which the DISG is operated without supplying fuel to the engine. In another example, the driver may specify a threshold torque above which the DISG assists the engine to provide the desired wheel torque. In yet another example, the driver may specify that the DISG should provide electrical energy to the batteries when the battery SOC is less than a driver input level. Method 400 continues at 484 after the driver is allowed to manually input the DISG operating conditions.At 484, method 400 allows the driver to manually input driveline disconnect clutch opening and closing conditions. For example, the driver may input a condition that the driveline disconnect clutch is to be closed in response to a particular driveline mode (e.g., the disconnect clutch is to be maintained closed in a low 4×4 mode and the disconnect clutch is to be selectively closed in the 4×2 and high 4×4 modes). In another example, the driver may input a condition to open the driveline disconnect clutch in response to a period of engine idle. In yet another example, the driver may specify that the driveline disconnect clutch is to be closed when the battery SOC is less than a driver specified value. Method 400 ends after the driver is allowed to manually input the engine conditions, driveline disconnect clutch conditions, and motor control conditions.Referring now to FIG. 4, method 400 operates the engine, driveline disconnect clutch, and DISG in accordance with the adjusted base automated conditions. More specifically, the calibrated baseline operating conditions of the engine, driveline disconnect clutch, and DISG are the basis for operating the engine, driveline disconnect clutch, and DISG except when specific changes to the driver have been input in the above portions of method 400. For example, if the driver requested PTO operation and requested that the DISG be operated until the battery SOC reaches a driver specified level, the engine, driveline disconnect clutch, and DISG are operated in accordance with the calibrated baseline conditions except when the vehicle is in a PTO mode using the DISG. Method 400 ends after the engine, driveline disconnect clutch, and DISG are operated in accordance with the adjusted conditions of the base operating mode.Thus, the method of FIGS. 4-10 provides for adjusting operation of a hybrid vehicle, the method comprising: adjusting a schedule for automatically stopping engine rotation in response to a condition of a roadway. The method includes where the condition of the roadway is a measure of surface roughness. The method also includes where the condition of the roadway is a measure of the frequency of turns. In this way, engine rotation may be stopped when the road conditions are good, while engine rotation may be continued when the road conditions have deteriorated. As a result, fuel consumption during conditions may be reduced when the driver is less likely to require additional torque from the engine.In an example, the method further comprises adjusting the plan in response to a road condition metric. The method further comprises adjusting opening of a driveline disconnect clutch in response to the condition of the roadway. The method includes where opening the driveline disconnect clutch is in accordance with a first schedule responsive to the hybrid vehicle being in a two-wheel drive mode and where opening the driveline disconnect clutch is in accordance with a second schedule, the second schedule different from the first schedule responsive to the hybrid vehicle being in a four-wheel drive mode. The method further includes automatically restarting the engine in response to the condition of the roadway degrading to a threshold level.In another example, the method of FIGS. 4-10 includes adjusting operation of a hybrid vehicle, the method comprising: adjusting a first schedule for automatic idling of an engine and decoupling the engine from a driveline in response to a condition of a roadway. The method includes where the driveline includes a DISG located in the driveline of the hybrid vehicle. The method also includes automatically restarting the engine in response to the condition of the roadway degrading to a threshold level. The method includes applying the first map when the hybrid vehicle is operated in a two-wheel drive mode. The method further includes a second map applied when the hybrid vehicle is operated in a four-wheel drive mode. In another example, the method further comprises adjusting the second schedule for automatic idling of an engine and decoupling the engine from a driveline in response to a condition of a roadway. The method further includes allowing the engine to stop rotation in response to the condition of the roadway.The method of FIGS. 4-10 also includes adjusting operation of a hybrid vehicle, the method comprising: adjusting operation of a driveline disconnect clutch positioned in the driveline of a hybrid vehicle in response to an approach speed to an obstacle in a path of the hybrid vehicle. The method further comprises adjusting operation of the driveline disconnect clutch in response to operating the hybrid vehicle in a four-wheel drive mode. The method further comprises adjusting operation of the driveline disconnect clutch in response to a condition of a roadway. The method further includes restarting an engine in response to the speed of approach to the obstacle. The method includes where the driveline disconnect clutch is positioned between an engine and a DISG. The method includes where adjusting the operation of the driveline disconnect clutch includes closing the driveline disconnect clutch responsive to the approach speed being greater than a threshold.Referring now to FIG. 11, a predicted example flow for operating a vehicle including a PTO is shown. The flow of FIG. 11 may be provided by the method of FIG. 4 performed in the system of FIGS. 1-3. FIG. 11 shows an example of PTO operation where the DISG is supplying torque only to the PTO. However, in some examples, the engine may also supply PTO torque.The first top graph of FIG. 11 shows a PTO request versus time. The X axis represents time while the Y axis indicates the PTO operation request state. A lower level of the PTO signal indicates the absence of a PTO operation request. A higher level of the PTO signal indicates the presence of a PTO operation request. Time increases from the left side of the graph to the right side of the graph.The second plot from the top of FIG. 11 shows battery state of charge versus time. The X-axis represents time while the Y-axis indicates a battery state of charge. The battery state of charge increases in the direction of the Y-axis arrow. Time increases from the left side of the graph to the right side of the graph. Horizontal line 1101 represents a minimum battery SOC at which the DISG is operating.The third top plot of FIG. 11 shows a PTO direction request versus time. The X axis represents time while the Y axis indicates the state of the PTO direction request. A lower level of the PTO direction request signal indicates to rotate the PTO in a forward direction (e.g., to rotate to the right). A higher level of the PTO direction request signal indicates to rotate the PTO in a reverse direction (e.g., to rotate the PTO leftward). Time increases from the left side of the graph to the right side of the graph.The fourth plot from the top of FIG. 11 shows the PTO direction of rotation versus time. The X axis represents time while the Y axis indicates the PTO direction. A lower level of the PTO direction signal indicates a PTO rotation in a forward direction (e.g., the right rotation). A higher level of the PTO direction signal indicates the PTO rotation in a reverse direction (e.g., the left rotation of the PTO). Time increases from the left side of the graph to the right side of the graph.The fifth plot from the top of FIG. 11 shows PTO torque versus time. The X axis represents time while the Y axis indicates PTO output torque. The PTO positive output torque increases in the direction of the Y-axis arrow. Time increases from the left side of the graph to the right side of the graph. In this example, regardless of the PTO rotational direction, the PTO output torque is always shown positive because the PTO is supplying torque to an external device.The sixth plot from the top of FIG. 11 shows DISG torque versus time. The X axis represents time while the Y axis indicates DISG output torque. The DISG positive output torque increases in the direction of the Y-axis arrow. Time increases from the left side of the graph to the right side of the graph. In this example, regardless of the PTO rotational direction, the DISG output torque is always shown positive because the DISG is supplying torque to an external device via the PTO.At time T 0 the PTO request is at a low level indicating the absence of a PTO request and a PTO output. The battery state of charge is at a relatively high level indicating that the PTO may operate solely under battery power during a period of time. The PTO direction request signal indicates that the PTO should operate in a forward direction when the PTO is engaged. The PTO direction also indicates that the PTO is rotating in a forward direction if engaged. The PTO output torque is shown at zero because the PTO is not engaged, and the DISG torque is also shown at zero.At time T 1 the PTO request signal transitions to a higher level to indicate that the PTO should be engaged in response to a driver or controller request. The PTO request signal may transition in response to an operator input or a controller request for PTO output. The battery state of charge begins to be slowly decreased as the DISG output increases, thereby increasing PTO torque. The PTO direction request remains in a forward direction, with the PTO rotating in a forward direction, as indicated by the graphical representation of the PTO direction.At time T 2 the PTO direction request transitions from forward to reverse in response to a driver or controller request. The PTO direction changes from forward to reverse shortly after the DISG and PTO torques have been decreased to allow the PTO direction to change. The PTO and DISG torques are decreased to avoid generating a torque disturbance to the driveline. The battery state of charge is further decreased as long as the DISG operation continues.At time T 3 the PTO request is still enabled, but the battery SOC is reduced to the minimum state of charge 1101 at which DISG operation is permitted. As a result, the DISG output torque and PTO torque are decreased in response to battery SOC. The PTO direction and the PTO direction request remain in a reverse state. By turning off the DISG, battery degradation may be avoided.In this way, a driveline including a DISG and a PTO may be operated to provide directional control. Further, PTO operation may be limited to reduce the possibility of battery and / or DISG degradation.In FIG. 12, a predicted example flow for operating a vehicle including a low gear mode in the 4×4 range is shown. The flow of FIG. 12 may be provided by the method of FIG. 4 performed by the system of FIGS. 1-3.The first top plot of FIG. 12 shows a low gear requirement of the 4×4 range versus time. The X axis represents time, while the Y axis represents the low gear requirement state of the 4×4 range. A lower level of the 4×4 range low gear signal indicates a lack of a 4×4 range low gear operation request. A higher level of the 4×4 range low gear signal indicates the presence of a 4×4 range low gear operation request. Time increases from the left side of the graph to the right side of the graph.The second plot from the top of FIG. 12 shows the desired wheel torque versus time. The X axis represents time while the Y axis represents desired wheel torque. The target wheel torque increases in the direction of the Y-axis arrow. Time increases from the left side of the graph to the right side of the graph.The third top plot of FIG. 12 shows engine operating state versus time. The X axis represents time while the Y axis indicates the operating state of the engine. A lower level of the signal of the operating state of the engine indicates that the engine has stopped rotation. A higher level of the signal of the operating state of the engine indicates that the engine is rotating according to its own power. Time increases from the left side of the graph to the right side of the graph.The fourth top graph of FIG. 12 shows the state of the vehicle brake pedal versus time. The X axis represents time while the Y axis indicates the state of the brake pedal. A lower level of the brake pedal signal indicates that the brake pedal is not applied or is released. A higher level of the brake pedal signal indicates that the brake pedal is being applied. Time increases from the left side of the graph to the right side of the graph.The fifth plot from the top of FIG. 12 shows engine torque versus time. The X axis represents time while the Y axis indicates engine output torque. The positive engine output torque increases in the direction of the Y-axis arrow. Time increases from the left side of the graph to the right side of the graph.The sixth plot from the top of FIG. 12 shows DISG torque versus time. The X axis represents time while the Y axis indicates DISG output torque. The DISG positive output torque increases in the direction of the Y-axis arrow. Time increases from the left side of the graph to the right side of the graph.At time T 0 the 4×4 range low gear request is at a low level indicating the absence of a 4×4 range low gear request. The desired wheel torque is at a medium level with the engine rotating according to its own power. The brake is not applied with both the DISG and engine providing torque to the driveline of the vehicle.At time T 1 the desired wheel torque is decreased in response to a driver releasing an accelerator pedal. Further, the brake pedal of the vehicle is applied by the driver, where engine and DISG torque are decreased in response to the decreased desired wheel torque. The engine continues to operate with the low gear of the 4×4 range not being requested.At time T 2 the desired wheel torque reaches zero, with the engine automatically stopped shortly thereafter, without the driver requesting the engine stop via a dedicated input having the only function of starting and / or stopping the engine. The engine state signal transitions to a low level to indicate that the engine has been stopped. The engine torque and the DISG torque are at a level of zero so that the vehicle is not being propelled. The vehicle brake remains in an applied state.At time T 3 the low speed of the 4×4 range is requested as indicated by the low speed signal of the 4×4 range transitioning to a higher level. The 4×4 range low gear signal may be activated in response to a driver request to enter the 4×4 range low gear. The driveline disconnect clutch (not shown) is also closed at time T 3 responsive to entering low gear 4×4 range.At time T 4 the vehicle brake state transitions to a lower level in response to a driver releasing a brake pedal. Because the vehicle is in a low gear of the 4×4 range, the engine is automatically started without driver input to a device having a single function of starting and / or stopping the engine (e.g., a starter switch) in response to releasing the brake pedal. Shortly thereafter, the target wheel torque increases in response to a driver depressing an accelerator pedal. The engine torque and the DISG torque also increase responsive to the increasing desired wheel torque to provide the desired wheel torque. Thus, the engine is automatically started in response to releasing the brake pedal when the vehicle is in the low gear of the 4×4 range. Such operation allows the driveline of the vehicle to receive a higher level of torque. The driveline disconnect clutch remains engaged during engine stop and restart periods.Between times T 4 and T 5 the engine torque and the DISG torque are increased responsive to a driver or controller request to provide the desired wheel torque. Further, the brake pedal remains in an inactivated state until the brake pedal is applied at a time T 5 as indicated by the state of the brake pedal transitioning to a higher level. The desired wheel torque signal is also decreased at time T 5 in response to the driver releasing the accelerator pedal. Further, the engine torque and the DISG torque are decreased in response to the decreased desired wheel torque at time T 5. The vehicle remains in the low gear of the 4×4 range. The engine is shut down and stops rotation shortly before time T 6. The period of time that elapses between the time when the target wheel torque reaches zero when the engine torque is decreased to make the engine idle and the DISG torque reaches zero and the time when the engine is stopped increases compared to when the vehicle is in 4×2 mode at time T 2 because the vehicle is in the low gear of the 4×4 range. This additional delay time is useful to allow a pause time between driving over rough roads without stopping the engine prematurely.At time T 6 the vehicle exits the 4×4 range low gear and transitions to a 4×2 wheel or a 4×4 range high gear in response to a driver request. The brake pedal continues to be applied as indicated by the brake state signal remaining at a higher level. The engine torque and the DISG torque remain at low levels.At time T 7 the desired wheel torque is increased in response to a driver or controller request. Because the vehicle is now not in the low gear of the 4×4 range, the engine remains stopped and the DISG output torque is increased to correspond to the desired wheel torque. Thus, without a driver wheel torque request, the DISG provides torque to the driveline including creep torque to slowly propel the vehicle to a threshold torque so fuel may be saved. The vehicle brake is also released by the driver as indicated by the braking state transitioning to a lower level.At time T 8 the desired wheel torque is increased to a level at which the engine is restarted in response to the desired wheel torque requested by a driver or controller. The engine torque is supplied to the driveline to correspond to the desired wheel torque after the engine is started as indicated by the engine state signal transitioning to a higher level. Thus, at time T, 8 both the engine and the DISG supply torque to correspond to the desired wheel torque.In this way, a driveline including a DISG and an engine may be operated differently when the vehicle is operating in a low gear of the 4×4 range compared to when the vehicle is operating in a different driveline mode. Such operation may limit the degradation of driveline components by limiting the number of transitions between applying and releasing the driveline disconnect clutch.In FIG. 13, a predicted example flow for operating a vehicle between the 4×2 and 4×4 modes is shown. The flow of FIG. 13 may be provided by the method of FIG. 4 performed in the system of FIGS. 1-3.The first plot from the top of FIG. 13 shows a plot of available engine modes versus time. The X axis represents time while the Y axis indicates available engine mode. When the available engine mode is at a value of one, the engine may be operated only when the engine is coupled to the DISG. Further, the engine continues to rotate when the available engine mode has a value of one. When the available engine mode is at a value of two, the driveline disconnect clutch may be in an open or a closed state. The engine continues to rotate when the engine mode has a value of two, and the engine may be idling when the driveline disconnect clutch is open. If the available engine mode has a value of three, engine rotation may proceed at idle, proceed off-idle, or be stopped to conserve fuel. The available engine modes change in response to the road condition metric described in the second plot. Time increases from the left side of the graph to the right side of the graph.The second top plot of FIG. 13 shows a road condition metric or value versus time. The X axis represents time while the Y axis represents road condition metric. The value of the road condition metric increases in the direction of the Y-axis arrow. Time increases from the left side of the graph to the right side of the graph. Horizontal lines 1301, 1302, 1303, and 1304 represent various threshold levels of the road condition metric where the available driveline mode changes. The road condition metric indicated by line 1301 represents a higher value of the road condition metric, where the road may be very smooth, very curved, or very rough. The road condition metric indicated by line 1302 represents a mean higher value of the road condition metric, where the road may be smooth, very curved, or rough. The road condition metric indicated by line 1303 represents a mean lower value of the road condition metric, where the road may be somewhat smooth, very curved, or rough. The road condition metric indicated by line 1304 represents a lower value of the road condition metric, where the road is not very smooth, very curved, or very rough.The third top plot of FIG. 13 shows engine operating state versus time. The X axis represents time while the Y axis indicates the operating state of the engine. When the engine state is at a value of one, the engine rotation is stopped. When the engine state is at a value of two, the engine operates at idle when the driveline disconnect clutch is open. Further, when the driveline disconnect clutch is closed and the engine state has a value of two, the engine may operate at idle or off-idle (e.g., at higher engine speeds). When the engine state is at a value of three, the engine may operate at idle or off-idle when the driveline disconnect clutch is closed. Time increases from the left side of the graph to the right side of the graph.The fourth plot from the top of FIG. 13 shows driveline mode versus time. The X-axis represents time while the Y-axis indicates driveline mode. A lower level of the driveline mode signal indicates that the driveline is in 4×2 mode. A higher level of the driveline mode signal indicates that the driveline is in 4×4 mode. Time increases from the left side of the graph to the right side of the graph.The fifth plot from the top of FIG. 13 shows driveline disconnect clutch state versus time. The X axis represents time while the Y axis indicates driveline disconnect clutch state. A higher level of driveline disconnect clutch state indicates that the disconnect clutch is closed and the engine is mechanically coupled to the DISG. A lower level of driveline disconnect clutch state indicates that the disconnect clutch is open and that the engine is not mechanically coupled to the DISG. Time increases from the left side of the graph to the right side of the graph.The sixth plot from the top of FIG. 13 shows the wheel torque request versus time. The X axis represents time while the Y axis indicates the desired wheel torque. The target wheel torque increases in the direction of the Y-axis arrow. Time increases from the left side of the graph to the right side of the graph.At time T 0 the available engine mode is at a value of three and indicates that the engine may be stopped, may be operated idling, or may be operated off-idle. Additionally, the road condition metric is at a level below the lower threshold 1304 with the driveline in 4×2 mode, as indicated by the driveline mode signal being in a lower state. The engine state value is at three and indicates that the engine may be operating at idle, operating outside idle, or stopping because the road state metric is less than the level indicated by horizontal line 1304.At time T 1 the road condition metric has increased to a value greater than the level indicated by lines 1304. The level of the road condition metric indicated by line 1304 is a level during the 4×2 mode, where the available engine mode changes in response to the value of the road condition metric. The road condition metric is changed in response to the road or surface conditions at which the vehicle is operating. The available engine mode signal changes to a value of two in response to the change in road condition metric. In particular, the available engine modes are changed so that the engine may be operated at idle or off-idle when the driveline disconnect clutch is open, but the engine may not be automatically stopped. The disconnect clutch remains closed and the wheel torque request remains relatively constant. Further, the driveline mode remains in 4×2 mode.At time T 2 the road condition metric has increased to a value greater than the level indicated by line 1301. The available engine mode signal changes to a value of one in response to the change in the road condition metric. Specifically, the available engine modes are changed so that the engine cannot be operated idle when the disconnect clutch is open and the rotation of the engine cannot be automatically stopped. The disconnect clutch remains closed and the wheel torque request remains relatively constant. Further, the driveline mode remains in 4×2 mode.Between time T 2 and time T 3 the driveline mode is changed from 4×2 to 4×4, with the wheel torque changed in response to a driver request. The road condition metric increases to a value above the horizontal line 1301. As a result, the available engine mode remains at a value of one to ensure that the driveline may be ready to respond to driver input during degraded driving conditions. The engine state remains at a value of three with the driveline disconnect clutch remaining closed.At time T 3 the road condition metric is decreased to a value less than that of the horizontal line 1301 in response to the road conditions. A deeper road condition metric indicates an improvement in driving conditions. The available engine mode changes to a value of two in response to the road condition metric decreasing. Further, wheel torque is relatively low so that the driveline disconnect clutch may be opened as shown. The engine will idle as indicated by the engine state changing to a value of one. The driveline mode remains in 4×4 mode. In this way, engine fuel consumption may be reduced by operating the engine at idle when the driveline disconnect clutch is maintained open. However, the engine may not be automatically stopped when the available engine mode is at a value of two.At time T 4 the road condition metric is decreased to a level below the horizontal line 1304 in response to the road conditions. Thus, the available engine mode is changed to a value of three to allow the engine to stop. The disconnect clutch remains in an open state with the driveline mode remaining in 4×4 mode. Between time T 4 and time T 5 the wheel torque increases and decreases in response to a driver request, closing the driveline disconnect clutch to provide the desired wheel torque via a combination of the engine and DISG torques. The driveline disconnect clutch is closed shortly before time T 5 when wheel torque exceeds a threshold level. The engine state changes from stopped to when the engine may be idling when the disconnect clutch is open. However, because the disconnect clutch is closed, the engine may be operated at higher speeds.At time T 5 the road condition metric increases to a value indicated by horizontal line 1304 in response to the road conditions. The available engine mode changes to a value of two to indicate that the engine may be operated idle and off-idle, but may not be automatically stopped. It can be observed that when the vehicle is operating in 4×4 mode, the available engine modes change at other levels of road condition metric compared to when the vehicle is operating in 4×2 mode. Such operation may reduce degradation of driveline components when the vehicle is operating in 4×4 mode. The engine state remains at a value of two indicating that the engine may be idling if the disconnect clutch is opened.At time T 6 the value of the road condition metric increases to a level greater than that of the horizontal line 1301. The available engine modes change to a value of three indicating that the engine cannot be automatically stopped. The engine state also changes to a level of three to indicate that the engine may operate at idle or off-idle when the disconnect clutch is closed. The engine state and available engine mode remain at the same levels until the end of the flow.As will be appreciated by one of ordinary skill in the art, the methods described in FIGS. 4-10 may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, the various steps or functions illustrated may be performed in the illustrated order, performed in parallel, or omitted in some cases. Likewise, the order of processing is not necessarily required to achieve the objects, features, and advantages described herein, but is provided for ease of illustration and description. Although not explicitly illustrated, one of ordinary skill in the art will recognize that one or more of the illustrated steps or functions may be repeatedly performed depending on the particular strategy being used.The following are generally described:A method for adjusting operation of a hybrid vehicle, the method comprising: adjusting a map for automatically stopping engine rotation in response to a state of a roadway.B method according to A, wherein the condition of the roadway is an estimate of the surface roughness.C method according to A or B, wherein the state of the roadway is a measure of the frequency of turns.The method of any of A-C, further comprising adjusting the plan in response to a road condition metric.The method of any of A-D, further comprising adjusting opening of a driveline disconnect clutch in response to the condition of the roadway.The method of any of A-E, wherein opening the driveline disconnect clutch is in accordance with a first schedule responsive to the hybrid vehicle being in a two-wheel drive mode, and wherein opening the driveline disconnect clutch is in accordance with a second schedule, the second schedule different from the first schedule responsive to the hybrid vehicle being in a four-wheel drive mode.The method of any of A-F, further comprising automatically restarting an engine in response to the condition of the roadway degrading to a threshold level.A method for adjusting operation of a hybrid vehicle, the method comprising: adjusting a first schedule for automatic idling of an engine and decoupling the engine from a driveline in response to a condition of a roadway.I method according to H, wherein the driveline includes a DISG located in the driveline of the hybrid vehicle.J method of H or I, comprising automatically restarting the engine in response to the condition of the roadway degrading to a threshold level.The K method of any one of H to J, wherein the first map is applied when the hybrid vehicle is operated in a two-wheel drive mode.L method according to any one of H to K, further comprising a second map applied when the hybrid vehicle is operated in a four-wheel drive mode.The M method of any of H to L, further comprising adjusting the second schedule for automatic engine idle and decoupling the engine from a driveline in response to a condition of a roadway.N method according to any one of H to M, further comprising allowing the engine to stop rotation in response to the state of the roadway.A method for adjusting operation of a hybrid vehicle, the method comprising: adjusting operation of a driveline disconnect clutch positioned in the driveline of a hybrid vehicle in response to an approach speed to an obstacle on a path of the hybrid vehicle.The method of O, further comprising adjusting operation of the driveline disconnect clutch in response to operating the hybrid vehicle in a four-wheel drive mode.The Q method of O or P, further comprising adjusting operation of the driveline disconnect clutch in response to a condition of a roadway.The R method of any one of O to Q, further comprising restarting an engine in response to the speed of approach to the obstacle.The method of any of O-R, wherein the driveline disconnect clutch is positioned between an engine and a DISG.The method of any of O-S, wherein adjusting the operation of the driveline disconnect clutch includes closing the driveline disconnect clutch in response to the approach speed being greater than a threshold.This concludes the description. Many changes and modifications would become apparent to those skilled in the art upon reading the specification without departing from the spirit and scope of the specification. For example, the present description could advantageously use R3, R4, R5, V6, V8, V10, and V12 engines operating on natural gas, gasoline, diesel, or alternative fuel configurations.Explanation of CharactersFIG. 4: START BEGIN 401 DETERMINE THE OPERATING CONDITIONS OF THE VEHICLE 402 A PTO HAS BEEN REQUESTED? NO YES to FIG. 5 403 CHARGE THE BATTERY AGAIN VIA THE DISG AFTER THE PTO HAS BEEN DEACTIVATED FROM FIG. 8 FROM AMONGs 5 U. 6 404 REQUEST FOR 4×4? 405, 407 A DETERIORATED STRAΒE HAS BEEN DETECTED? 406 operate the engine, disconnect clutch and motor in the automated base modes to FIG. 7 408 REQUEST FOR LOW 4×4? TO Figure 9 409 START ON BRAKE RELEASE ENGINE NOT FROM Figure 9 TO Figure 10 410 IS ENGINE, DISCONNECT CLUTCH AND MOTOR MANUAL CONTROL REQUESTED? 411 DRIVE ENGINE, Disconnect clutch and motor in the adjusted base automated states of finish FIG. 5: FROM FIG. 4 412 STATIONARY PTO MODE NO YES TO FIG. 6 413 IF THE ONLY DISG PTO MODE HAS BEEN SELECTED? 414 IS BATTERY SOC GREATER THAN A THRESHOLD? 415 IF AN IMMINENT SHUTDOWN OF THE DISG AT 416 END OPERATION OF THE DISG 417 OPEN DISCONNECT CLUTCH 418 TAU CONTROL SIGNALS WITH THE PTO DRIVEN DEVICE 419 REVERSE ROTATION HAS BEEN REQUESTED? 420 RETURN DIRECTION OF THE DISG AND PTO AT 421 IF THE PTO DEVICE IS AT THE LIMIT? 423 STOP ROTATION OF THE DISG AND PTO 424 IS BATTERY SOC GREATER THAN A THRESHOLD? 425 ENABLE ENGINE 426 END providing positive torque via the disg 427 may provide the disg desired torque? 428 closeE DISCONNECT CLUTCH AND ENGINE 429 MAY PROVIDE THE ENGINE ALONE? 430 CLOSE ENGINE TORQUE TO PROVIDE THE DESIRED WHEEL TORQUE WHILE PTO DRIVES THE OUTERE DEVICE 431 CLOSE ENGINE TORQUE AND THE DOG TORQUE TO PROVIDE THE DESIRED WHEEL TORQUE WHILE PTO DRIVES THE OUTERE DEVICE 432 OPEN DISCONNECT CLUTCH AND STOP ENGINE 433 CLOSE THE DISG TORQUE TO PROVIDE THE DESIRED WHEEL TORQUE WHILE PTO DRIVES THE OUTERE DEVICE to FIG. 4 : FROM FIG. 4 440, FROM FIG. 4 440, FROM FIG. 4, 450 IS THE APPROACH SPEED TO THE OBSTACLE GREATER THAN A FIRST THRESHOLD VALUE OR IS THE ON STATE GREATER THAN A FIRST THRESHOLD VALUE? NO YES 441, 451 STOP ENGINE AUTOMATICALLY AND IDLE STANDBY MODE 442, 452, 446, 456 HAS STOPPED ENGINE? 443, 453, 447, 457 START ENGINE NEW 444, 454 IS THE APPROACH SPEED TO THE OBSTACLE LESS THAN A FIRST THRESHOLD AND GREATER THAN A SECOND THRESHOLD OR THE IDLE STATE IS LESS THAN A FIRST THRESHOLD AND GREATER THAN A SECOND THRESHOLD? 445, 455, 449 ALLOW ENGINE AUTOMATIC IDLE STANDBY MODE AND NOT STOP ENGINE 448, 458 is the approach speed to the obstacle less than a second threshold and greater than a third threshold or the road condition is less than a second threshold and greater than a third threshold? 459 permits automatic stopping of the engine until rotation from zero to FIG. 8, FIG. 10 : FROM 4 470 SHIFT TO MANUAL RELEASE CLUTCH? NO Yes 471 engaged the clutch close? 472 engaged the clutch close because 473 requested the only-disconnect mode? 474 opened the clutch lock-up 475 is the battery soc less than a threshold? 476 started the engine new 477 requested the disconnect as unavailable if the requested torque is greater than available engine torque 478 requested the engine only mode? 479 deactivated the disconnect 480 requested the downhill mode? 481 lock-upE CLUTCH and INCREASE ENGINE BRAKING AND DISCONNECT BASED ON THE SLOPE 482 ALLOW THE MANUAL INPUT OF THE ENGINE STOP CONDITIONS 483 ALLOW THE MANUAL INPUT OF THE DISCONNECT MODE 484 ALLOW THE MANUAL INPUT OF THE DISCONNECT CLUTCH MODE to terminate the manual input of the disconnect clutch mode

Claims

A method for adjusting operation of a hybrid vehicle, the method comprising: adjusting a schedule for automatically stopping engine rotation in response to a condition of a roadway, further comprising adjusting opening of a disconnect clutch (236) of a driveline (200) in response to the condition of the roadway, wherein opening of the disconnect clutch (236) of the driveline (200) is in accordance with a first schedule in response to the hybrid vehicle being in a two-wheel drive mode, and wherein opening of the disconnect clutch (236) of the driveline (200) is in accordance with a second schedule, the second schedule being different than the first schedule, in response to the hybrid vehicle being in a four-wheel drive mode.The method of claim 1, wherein the condition of the roadway is an estimate of a surface roughness.The method of claim 1, wherein the condition of the roadway is a measure of a frequency of turns.The method of claim 1, further comprising setting the schedule in response to a road condition value.The method of claim 1, further comprising automatically restarting an engine (10) in response to the condition of the roadway degrading to a threshold level.

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