Method and system for active steering of start-stop events

Abstract

The present disclosure provides "Methods and systems for active steering of start-stop events". A vehicle is provided. The vehicle can include an engine configured to automatically stop and automatically start. The system can also include a controller programmed to power an electric actuator coupled to a steering mechanism to synchronize a drive angle of the vehicle with a steering wheel angle of the vehicle in response to a parameter indicative of a likelihood of a wheel slip event exceeding a threshold and the steering wheel angle being greater than a predetermined threshold.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a vehicle system for turning a vehicle during start-stop events and a method of operating the vehicle system. BACKGROUND

[0002] Fuel economy and emissions performance are important characteristics for automobiles. Higher fuel economy and lower emissions ratings can make a vehicle more attractive to potential buyers and can help automobile manufacturers meet fuel economy and emissions standards imposed by local governments. For traditional gasoline or diesel vehicles, one method of reducing fuel consumption is to use a micro-hybrid or start-stop powertrain system that selectively shuts off its engine during portions of a drive cycle (automatic stop events).

[0003] Some vehicles include an active front steering (AFS) system to improve steering performance. The AFS system can be electromechanical and include an electronically controlled motor and gear assembly that superimposes additional steering angle based primarily on vehicle speed and steering wheel angle. Under certain conditions, such as automatic stop events, the AFS motor stops or freezes, so movement of the steering wheel does not change the position of the wheels. When the AFS motor is frozen, the AFS motor will remain in the current position regardless of additional movement of the steering wheel. Since the AFS motor holds the angle of the wheels, movement of the steering wheel can cause a mismatch or error between the steering wheel and the wheels. SUMMARY

[0004] According to one embodiment of the present disclosure, a method of controlling an active steering system is provided. The method can include powering, by a controller, an electric actuator coupled to a steering mechanism to synchronize a drive angle of a vehicle with a steering wheel angle of the vehicle in response to a parameter indicating that a wheel slip event exceeds a threshold and the steering wheel angle is greater than a predetermined threshold.

[0005] According to another embodiment of the present disclosure, a vehicle system is provided. The system can include an engine configured to automatically stop and automatically start. The system can also include a controller programmed to initiate automatic starting of the engine in response to a difference between a steering wheel angle and a drive angle being greater than a predetermined threshold.

[0006] According to yet another embodiment of the present disclosure, a vehicle is provided. The vehicle can include an engine configured to automatically stop and automatically start. The system can also include a controller programmed to power an electric actuator coupled to a steering mechanism to synchronize a drive angle of a vehicle with a steering wheel angle of the vehicle in response to a parameter indicating that a wheel slip event exceeds a threshold and the steering wheel angle is greater than a predetermined threshold. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a diagram of an exemplary steering system including active front steering.

[0008] Figure 2 is a diagram of an exemplary stop / start vehicle showing typical components.

[0009] Figure 3 is a flowchart of operating a stop / start vehicle and associated steering system according to a first embodiment of the present disclosure.

[0010] Figure 4 is a flowchart of operating a stop / start vehicle and associated steering system according to a second embodiment of the present disclosure. DETAILED DESCRIPTION

[0011] Detailed embodiments of the application are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the application and can be embodied in various and alternative forms. The Figures are not necessarily to scale; some features can be exaggerated or minimized for the purpose of brevity, clarity, and understanding. The

[0012] In some cases, the angle of the steering wheel and the angle of the vehicle wheels (e.g., the drive angle) can not match. Synchronizing the drive angle and the steering wheel angle can be more difficult in low traction conditions. To correct for this mismatch, a controller can power an electric actuator coupled to a steering mechanism to synchronize the drive angle of the vehicle and the steering wheel angle of the vehicle.

[0013] The objective of a controller of a start-stop vehicle powertrain system can include stopping an engine, such as an internal combustion engine (e.g., a gasoline engine or a diesel engine). The controller can be used to stop the engine by suppressing the ignition coil of the engine or by suppressing fuel injection into the engine cylinders. The controller can stop the engine based on input from sensors of the vehicle. The signals from the sensors can indicate the speed of the vehicle, the force applied to the brake pedal (or absence thereof), the force applied to the accelerator pedal (or absence thereof), the angle of inclination of the vehicle, the weight of the vehicle, or other vehicle characteristics. An extension of conventional start-stop is a roll-stop system (RSS).

[0014] Conventional start-stop systems can be configured to automatically stop the engine when the vehicle is not moving (e.g., 0 mph), force is applied to the brake pedal, and the voltage level of the vehicle battery is above a threshold. The threshold is selected based on the energy required to start the engine via an electric starter. Once the engine is stopped, the controller can automatically start the engine if the gear selector is in drive and no force is applied to the brake pedal. In other embodiments of start-stop vehicles, the controller can be configured to automatically stop the engine when the vehicle is moving below a low speed threshold (e.g., 2 mph or 4 mph), force is applied to the brake pedal, and the voltage level of the vehicle battery is above a threshold. Along with conventional start-stop control systems, the vehicle can be configured to start-stop the engine when the vehicle is moving above a lower threshold. This system is also referred to as a rolling start-stop system (RSS).

[0015] RSS can have additional benefits, such as improving fuel economy ratings, improving vehicle emissions, and reducing engine noise. These benefits can complement the improvements from conventional start-stop systems. RSS allows the engine to be automatically stopped at higher vehicle speeds once the driver applies the brakes, the vehicle speed is less than the vehicle upper speed threshold, the torque converter clutch of the transmission is open, and the transmission is in the appropriate gear.

[0016] Generating energy through the engine only when needed / required is one of the primary methods of maximizing fuel economy while minimizing emissions in vehicles equipped with internal combustion engines. As a result, RSS systems are being considered for implementation in various modern vehicles in all major markets globally. RSS systems can include a battery system that can implement a single battery, dual batteries, any number of batteries. The battery system can have a working voltage approximately equal to a standard vehicle battery (i.e., 12 volts), or can operate at other voltages (e.g., 24V, 48V, etc.). The RSS system can utilize any combination of batteries or power sources of the same or different technologies, such as lead-acid, enhanced flooded (EFB), absorbent glass mat (AGM), LI-Ion, or any other battery technology.

[0017] One of the challenges in implementing RSS technology in vehicles is controlling the steering system of the vehicle during low power situations (automatic stop events). When the vehicle is stopped, there can not be enough energy to power the AFS motor to adjust the drive angle of the vehicle wheels to match the angle of the steering wheel. This challenge can be more complicated when the vehicle is operating on a low friction surface, such as snow, rain, or ice. Sensors configured to detect such conditions can communicate with the controller to change the AFS system and the RSS system.

[0018] REFERENCE Figure 1FIG. 1 shows a diagram of an example vehicle 10. FIG. 2 shows a diagram of an example steering system 28 for the vehicle 10. The steering system 28 can include an active front steering (AFS) module 20. The AFS module 20 can assist in driving a steering mechanism 24 to change a gear ratio of wheel rotation in response to rotation of a steering wheel. For example, at lower vehicle speeds, a low gear ratio can be implemented such that the steering wheel turns less for a given steering angle. This allows for sharp turns with less steering wheel input. At higher vehicle speeds, the gear ratio can be increased such that the steering wheel turns more for a given steering angle. This reduces the sensitivity of the steering system 28 to changes in the steering wheel at higher speeds. The net effect is that the wheels turn less in response to rotation of the steering wheel at higher speeds.

[0019] The steering system 28 can include an electric power assisted steering (EPAS) module 22 that can work in conjunction with the steering mechanism 24. The EPAS module 22 can assist in driving the steering mechanism 24 to reduce the amount of driver effort needed to steer the vehicle 10. The EPAS module 22 can include an electric motor that assists in driving the steering mechanism 24. In addition to the torque provided by the driver, the EPAS module 22 can add torque to change the direction of the front wheels.

[0020] The steering system 28 can include a steering wheel 50 that is operated by the driver. The steering system 28 can convert steering wheel 50 motion to displacement of the front wheels 52 to cause a change in direction of the vehicle 10. The steering mechanism 24 can be a rack and pinion configuration, in which the front wheels 52 are coupled to a rack 60 and the steering wheel 50 is coupled to a pinion 62.

[0021] The AFS module 20 can include an electric actuator or motor 56 that is coupled to a helical or planetary gear set 58. The motor 56 can cause the pinion 62 to rotate, which can cause the rack 60 to move and the front wheels 52 to change direction. The steering wheel 50 can also be coupled through the AFS gear set 58. When the steering wheel 50 is turned, a variable gear ratio between the steering wheel 50 and the wheel 52 rotation can be created by operating the AFS module 20 to drive the pinion 62. The gear ratio can be a ratio between the steering wheel angle and the angle of wheel rotation (e.g., drive angle). A controller 54 can receive a steering wheel angle input signal 64 that is indicative of the position of the steering wheel 50 and can generate one or more output signals 66 to operate the motor 56. The controller 54 can utilize additional inputs and outputs. The controller 54 can communicate with other controllers, such as an engine controller or a vehicle system controller.

[0022] The controller 54 can be programmed to monitor the steering wheel angle input signal 64 from the steering wheel 50. The controller 54 can also be programmed to monitor the drive angle. For the purposes of this disclosure, the "drive angle" represents the current position of the wheels 52. The controller 54 can determine the positional difference between the steering wheel angle and the drive angle (e.g., the AFS error). Based on the AFS error, the controller 54 can determine the required current for the motor 56. The controller 54 can control the current through the motor 56 via an output signal 66.

[0023] The AFS module 20 can include a lock mechanism 68. The lock mechanism 68 can be a solenoid actuated device that, when actuated, prevents the motor 56 from rotating the pinion 62. When the lock mechanism 68 is engaged, the AFS module 20 is unable to assist in turning the vehicle, and steering is accomplished using the steering wheel 50 output. The lock mechanism 68 can be controlled by an output signal 70 from the controller 54.

[0024] The EPAS 22 and AFS 20 modules are coupled to the power network 18 and obtain power from the motor 14 or the battery 119. During operation, the EPAS 22 and AFS 20 modules can draw a significant amount of current from the power network 18. Under conditions where the engine 102 is running and the motor 14 is supplying power to the power network 18, the energy stored in the battery 119 can not be depleted. However, when the engine 102 is not running, power is provided by the battery 119. As a result, the voltage of the power network 18 can drop, which can negatively impact the EPAS 22 or AFS 20 modules. For example, the voltage can drop low enough that the EPAS 22 or AFS 20 modules do not function adequately.

[0025] Reference Figure 2The micro-hybrid vehicle 10 (also referred to as a stop-start vehicle) includes an engine 102 and a transmission 104. A crankshaft of the engine 102 is drivingly connected to a transmission input shaft 106 to transmit power from the engine to the transmission. The transmission 104 includes an output shaft 108 that is drivingly connected to a differential 110. The differential 110 selectively provides power to driven wheels 114A and 114B via one or more axles, such as half shafts 112A and 112B. In some embodiments, the differential 110 is housed within the transmission housing. The vehicle 10 also includes an engine-starter motor 116 that is configured to rotate the crankshaft to crank the engine 102 in response to an engine start signal from the controller 54. The engine-starter motor 116 can be an enhanced starter motor that is specifically designed for the increased duty cycle associated with micro-hybrid vehicles. The starter 116 is powered by a battery 119, which can be a 12-volt battery, a 24-volt battery, a 48-volt battery, or other low-voltage or high-voltage battery.

[0026] A low-voltage battery is a battery having a direct current voltage less than 100 volts, and a high-voltage battery is a battery having a direct current voltage equal to or greater than 100 volts. In some embodiments, the engine can include multiple starter motors. A first starter motor can engage a ring gear of a flywheel to crank the engine. A second motor can be connected to a crank pulley by a belt, chain, or other means known in the art. Specifically, in the case of an RSS, the vehicle can have a dual battery system, i.e., a 12-volt battery for cranking and a 12-volt battery for supporting electrical loads when the engine is off and the vehicle is moving. The two batteries are typically isolated by a disconnect switch.

[0027] An accelerator pedal 122 provides driver input to control the speed of the vehicle 10. The pedal 122 can include a pedal position sensor that provides a pedal position signal to the controller 54, which provides a control signal to the engine 102.

[0028] A brake pedal 124 provides driver input to control the brakes of the vehicle. A brake controller 126 receives driver input through the brake pedal 124 and controls a friction brake system including wheel brakes 130A and 130B that are operable to apply brake force to wheels, such as wheels 114A and 114B. The pedal 124 can include a pedal position sensor that provides a pedal position signal to the controller 54. The vehicle can include an electric park brake in communication with the controller 54. The controller 54 is programmed to automatically engage the park brake when needed.

[0029] In another embodiment, the vehicle can be equipped with a manual transmission and an associated clutch pedal (not shown). As with the above-mentioned pedal 124, the clutch pedal can be equipped with a pedal sensor that provides a pedal position signal to the controller 54.

[0030] The controller 54 can be multiple controllers that communicate via a serial bus (e.g., Controller Area Network (CAN), FlexRay, Ethernet, etc.) or via dedicated electrical conduits. The controller typically includes any number of microprocessors, microcontrollers, ASICs, ICs, volatile memory (e.g., RAM, DRAM, SRAM, etc.) and non-volatile memory (e.g., flash memory, ROM, EPROM, EEPROM, MRAM, etc.) and software code to act in concert with one another to perform a series of operations. The controller can also include "look-up tables" of predetermined data or based on calculated and tested data and stored within memory. The controller can communicate with other vehicle systems and controllers using a common bus protocol (e.g., CAN, LIN, Ethernet, etc.) over one or more wired or wireless vehicle connections. Reference to a "controller" as used herein refers to one or more controllers.

[0031] As described above, embodiments of the present application include control systems for controlling the start-stop system of an engine in a vehicle, such as engine 102 and vehicle 10. Such control systems can be embodied by one or more controllers, such as controller 54. One goal of a vehicle start-stop system is to automatically stop the engine under certain conditions, while automatically restarting the engine when conditions change. This provides for higher fuel economy and reduced emissions.

[0032] In some start-stop systems, the engine can be automatically stopped ("auto-stop") when all or a set of specific conditions are met. For example, if the shift lever is in "drive," the brake pedal is depressed, the accelerator pedal is released, and the vehicle is at rest, then the engine 102 can be auto-stopped. Another condition that can be included in this set of conditions is that no vehicle subsystems (e.g., air conditioning or power steering) require engine operation. In a start-stop system where all conditions need to be met before the engine is auto-stopped, if any one of the conditions in the set is not met, then the start-stop system will not only prevent the engine from being auto-stopped, but if the engine has already been auto-stopped, the engine can be auto-restarted if any one of the conditions changes.

[0033] Continuing the example above, one of the common conditions for the engine to stop is for the vehicle's speed or velocity to be zero. Generally, the engine will not be stopped while the vehicle is in motion. In some systems, the vehicle velocity can be greater than zero, but less than a lower speed threshold, such as 1.5 mph or 3.5 mph. Herein, if the vehicle's speed is within the speed range, the roll start-stop system allows the engine 102 to be automatically stopped.

[0034] Another vehicle characteristic to consider when calculating the engine cutoff point is the capacity and pressure of the vacuum reservoir used to provide brake boost vacuum assist. The upper threshold speed can be selected from a range of speeds, such as 15 mph to 60 mph. The ability of the vehicle to turn and stop depends on many conditions of the vehicle, including speed, weight, angle of incline, brake condition, road conditions, and tire condition. As these conditions change, the ability of the vehicle to turn and stop changes. For example, a vehicle traveling downhill is more difficult to stop than a vehicle traveling uphill. Accordingly, the controller 54 can be configured to set a fixed lower threshold based on the lower speed to prevent a range of conditions that affect the vehicle's ability to stop. Also, the controller 54 can be configured to set a fixed upper threshold based on the upper speed to prevent a range of conditions that affect the vehicle's ability to stop. Alternatively, the controller 54 can be configured to dynamically change the lower threshold and the upper threshold based on the conditions of the vehicle at a certain point in time.

[0035] The vehicle 10 can be equipped to detect or determine the presence of a low-friction road surface. The presence of a low-friction surface can cause the wheels 52 to slip or spin and subsequently prevent the vehicle from reaching a desired speed. More specifically, the vehicle 10 can include a temperature sensor 138 in communication with the vehicle sensors 128 and the controller 54. If the ambient temperature around the vehicle 10 is below a threshold (e.g., 32 degrees Fahrenheit), the controller 54 can determine the likelihood of a wheel slip event. The vehicle can also include a rain sensor 140 in communication with the vehicle sensors 128 and the controller 54. If rain or other precipitation (e.g., snow, sleet, or ice) is detected, the controller 54 can determine the likelihood of a wheel slip event. The vehicle can also include a traction control module 142. The traction control module 142 can include an anti-lock braking system capable of detecting skids or wheel slips. Further, the traction control module 142 can include wheel speed sensors that measure the rotational speed of the wheels 52 and 114. The traction control module 142 or the controller 54, or both, can detect a difference in rotational speed between the wheels 52 and 114. If one or more of the wheels (e.g., 52a) is rotating faster than the other wheels (e.g., 52b, 114a, or 114b), a slip condition can be detected.

[0036] The controller 54 can also be configured to dynamically change the vehicle speed threshold based on the conditions of the vehicle at some future point in time. For example, a navigation system or a human machine interface (HMI) including the navigation system 132 can be coupled with the controller 54 such that a route can be provided to the controller. The route can include changes in elevation along the route and adjust the upper and lower speed thresholds according to potential braking changes along the route. The route can also include changes in posted speed that indicate locations where the brakes can be applied to reduce speed or the accelerator can be used to increase speed. The route can include locations of potential stops, such as static and dynamic locations. Static locations of potential stops include traffic lights, stop signs, round-abouts, or yield signs. Dynamic locations of potential stops along the route include locations associated with traffic congestion, weather conditions, road construction, or accidents. The route displayed by the navigation system within the HMI 132 can be based on map data that has been pre-loaded in the memory of the HMI 132 or the HMI 132 can receive data streamed from a remote server. The data can be streamed wirelessly using cellular, Wi-Fi, or other standard technologies. Based on the route, changes in elevation, and potential stops along the route, the controller 54 can adjust the voltage level of the starter battery 118 to maintain the state of charge of the starter battery 118. This adjustment reserves power for electrical accessories powered by the battery 118, including electric power steering (EPS), electric brakes, electric stability control (ESC), and other vehicle dynamics systems.

[0037] Referring now to Figure 3 , a flowchart illustrating a system or method 300 of active front steering system 28 and operation of the start-stop system of the vehicle 10 is shown. As previously described, the various functions or processes shown can be performed in different orders, can be omitted, or can be repeated, as explicitly shown or described, to achieve the various features and advantages described herein, as will be understood by one of ordinary skill in the art.

[0038] Controlling or operating the active front steering system 28 and the start-stop system of the vehicle 10 can begin at operation 302. When the speed of the vehicle decreases below a threshold value V, as represented by operation 304, the controller 54 can automatically stop the vehicle 10, as represented by operation 306. The controller 54 can receive a signal indicating a resumption of travel, as represented by operation 308. The signal can be triggered by a user or driver depressing the accelerator pedal 122 or placing the gear selector in the drive state and without force applied to the brake pedal.

[0039] As previously mentioned, the controller 54 monitors the AFS error, the difference in angle, between the drive angle (e.g., the current wheel position) and the steering wheel angle (as positioned by the driver or operator). In some cases, the AFS error can change (increase or decrease). There can be a relatively small AFS error (0.1 to 5 degrees) if the steering mechanism 24 is not aligned with the steering wheel 50. This can be due to an incorrect alignment process, or occurring after one of the wheels 52 hits a pothole or curb. The AFS error can increase after the steering wheel 50 and wheels 52 are turned before the vehicle 10 is automatically stopped and after the steering wheel 50 is turned in the opposite direction. Alternatively, the AFS error can be caused or increased by adjusting the steering wheel 50 during an automatic stop event. Alternatively, the AFS error can be caused or increased by engaging the safety lock when turning the steering wheel 50. If the change in the AFS error exceeds a threshold x, as represented by operation 310, the controller 54 branches to operation 312.

[0040] If the error exceeds the threshold x, the AFS system 28 sends a signal to the controller 54 to automatically start the engine 102, as represented by operation 312. The powertrain or engine 102 is restarted, and the vehicle is automatically started, as represented by operation 314, as represented by operation 316. Once the vehicle 10 has been automatically started, sufficient power is provided to the AFS electric actuator or motor 56, as represented by operation 318. Once sufficient power is provided to the motor 56, the AFS error can be reduced by synchronizing the drive angle with the steering wheel angle. Synchronizing the drive angle and the steering wheel angle can occur gradually (e.g., 3-20 minutes).

[0041] Referring now to Figure 4 , a flowchart illustrating the operation of a system or method 400 of the active front steering system 28 and the start-stop system of the vehicle 10 is shown. As previously described, the various functions or processes shown can be performed in different orders, can be omitted, or can be repeated, but are not explicitly shown or described to implement the various features and advantages described herein, as will be understood by one of ordinary skill in the art.

[0042] Controlling or operating the active front steering system 28 and the start-stop system of the vehicle 10 can begin at operation 302. When the speed of the vehicle decreases below a threshold V, the controller 54 can automatically stop the vehicle 10, as represented by operation 304, as represented by operation 306. The controller 54 can receive a signal indicating a resumption of travel, as represented by operation 308. The signal can be triggered by a user or driver depressing the accelerator pedal 122 or placing the gear selector in the drive state and without a force applied to the brake pedal.

[0043] The controller 54, the traction control module 142, or some combination thereof can determine the likelihood of a wheel-slip condition, as represented by operation 400. As previously mentioned, the likelihood of a wheel-slip condition can vary with the vehicle-external temperature measured by the temperature sensor 138. The likelihood of a wheel-slip condition can depend on the presence of precipitation measured by the rain sensor 140. In addition, the traction control module 142 can detect or predict a wheel-slip condition. If the likelihood of a wheel-slip condition exceeds a predetermined threshold Y, the controller moves to operation 402.

[0044] In another embodiment, the vehicle can be equipped with an imaging device (e.g., a camera) to detect the presence of precipitation on the driving surface.

[0045] The controller 54 can also determine the angle of the steering wheel and whether the steering wheel angle exceeds a threshold a, as represented by operation 402. If the steering wheel angle exceeds the threshold a, the controller moves to operation 318. The controller 54 can then provide sufficient power to the AFS motor 56, as represented by operation 318. Once the AFS motor 56 is energized, the AFS motor 56 can be actuated to synchronize the drive angle with the steering wheel angle, as represented by operation 320. Referring back to operation 402, if the steering wheel angle is less than the threshold a, the controller moves to operation 404. In operation 404, the controller then allows for a subsequent automatic stop event.

[0046] While the foregoing describes exemplary embodiments, it is not intended to describe all possible forms of the application. Rather, the words used in this specification are words of description, not limitation, and it is understood that various changes can be made without departing from the spirit and scope of the application. Additionally, features of various implementing embodiments can be combined to form further embodiments of the application.

[0047] According to the present application, a method of controlling an active steering system of a vehicle includes powering, by a controller, an electric actuator coupled to a steering mechanism to synchronize a drive angle of the vehicle with a steering wheel angle of the vehicle in response to a parameter indicating that a likelihood of a wheel-slip event exceeds a threshold and the steering wheel angle is greater than a predetermined threshold.

[0048] According to one embodiment, the parameter is based on a detection of precipitation by a precipitation sensor.

[0049] According to one embodiment, the parameter is based on a difference in rotational speed between a first wheel and a second wheel.

[0050] According to one embodiment, the parameter is based on an external temperature being less than a predetermined temperature threshold.

[0051] According to one embodiment, the above features of the invention are further characterized by initiating an automatic start after the powering.

[0052] According to the invention, there is provided a vehicle system comprising: an engine configured to automatically stop and automatically start; and a controller programmed to initiate automatic starting of the engine in response to a difference between a steering wheel angle and a drive angle being greater than a first predetermined threshold.

[0053] According to one embodiment, the controller is further programmed to power the electric actuator to reduce the difference to a second predetermined threshold that is less than the first predetermined threshold in response to the automatic starting of the engine.

[0054] According to one embodiment, the controller is further programmed to initiate automatic starting of the engine in response to an increase in an angle error that exceeds an angle error threshold between the steering wheel angle and the drive angle before the engine automatically stops and the steering wheel angle and the drive angle after the engine automatically stops.

[0055] According to one embodiment, the controller is further programmed to power the electric actuator to reduce the angle error.

[0056] According to one embodiment, the controller is further programmed to command the electric actuator to adjust an angular position of one or more wheels.

[0057] According to one embodiment, the controller is further programmed to command the electric actuator to adjust an angular position of the steering wheel mechanism.

[0058] According to the invention, there is provided a vehicle having: an engine configured to automatically stop and automatically start; and a controller programmed to power an electric actuator coupled to a steering mechanism to synchronize a drive angle of the vehicle with a steering wheel angle of the vehicle in response to a parameter indicative of a likelihood of a wheel slip event exceeding a threshold and the steering wheel angle being greater than a predetermined threshold.

[0059] According to one embodiment, the controller is further programmed to power the electric actuator in response to a measured temperature outside the vehicle being less than a temperature threshold.

[0060] According to one embodiment, the controller is further programmed to power the electric actuator in response to a precipitation sensor sending a signal indicative of the presence of precipitation.

[0061] According to one embodiment, the controller is further programmed to power the electric actuator in response to a wheel speed difference between at least two of the wheels exceeding a wheel speed error threshold.

[0062] According to one embodiment, the predetermined threshold is forty-five degrees.

[0063] According to one embodiment, the controller is further configured to automatically stop the engine in response to the steering wheel angle being less than the predetermined threshold.

[0064] According to one embodiment, the predetermined threshold is forty-five degrees.

Claims

1. A method of controlling an active steering system of a vehicle, the method comprising: powering, by a controller, an electric actuator coupled to a steering mechanism to synchronize a drive angle of the vehicle with a steering wheel angle of the vehicle in response to a parameter indicative of a likelihood of a wheel slip event exceeding a threshold and the steering wheel angle being greater than a predetermined threshold.

2. The method of claim 1, wherein the parameter is based on a detection of precipitation by a precipitation sensor.

3. The method of claim 1, wherein the parameter is based on a difference in rotational speed between a first wheel and a second wheel.

4. The method of claim 1, wherein the parameter is based on an outside temperature being less than a predetermined temperature threshold.

5. The method of claim 1, further comprising initiating an automatic start after the powering.

6. A vehicle system, the vehicle system comprising: an engine configured to automatically stop and automatically start; and a controller programmed to initiate an automatic start of the engine in response to a difference between a steering wheel angle and a drive angle being greater than a first predetermined threshold.

7. The vehicle system of claim 6, wherein the controller is further programmed to power an electric actuator to reduce the difference to a second predetermined threshold that is less than the first predetermined threshold in response to the automatic start of the engine.

8. The vehicle system of claim 7, wherein the controller is further programmed to initiate an automatic start of the engine in response to an increase in an angle error, a difference between the steering wheel angle and the drive angle before the engine automatically stops and the steering wheel angle and the drive angle after the engine automatically stops exceeding an angle error threshold.

9. The vehicle system of claim 8, wherein the controller is further programmed to power the electric actuator to reduce the angle error.

10. The vehicle system of claim 9, wherein the controller is further programmed to command the electric actuator to adjust an angular position of one or more wheels.

11. The vehicle system of claim 9, wherein the controller is further programmed to command the electric actuator to adjust an angular position of a steering wheel mechanism.

12. A vehicle, the vehicle comprising: an engine configured to automatically stop and automatically start; and a controller programmed to power an electric actuator coupled to a steering mechanism to synchronize a drive angle of the vehicle with a steering wheel angle of the vehicle in response to a parameter indicative of a likelihood of a wheel slip event exceeding a threshold and the steering wheel angle being greater than a predetermined threshold.

13. The vehicle of claim 12, wherein the controller is further programmed to power the electric actuator in response to a measured temperature outside of the vehicle being less than a temperature threshold.

14. The vehicle of claim 12, wherein the controller is further programmed to power the electric actuator in response to a precipitation sensor sending a signal indicative of the presence of precipitation. ​ ​ 15. The vehicle of claim 12, wherein the controller is further programmed to power the electric actuator in response to a wheel speed difference between at least two of the wheels exceeding a wheel speed error threshold.

Images