Brake steering lateral stability management based on stability indicator correlation

Abstract

A number of variations are disclosed, including a system and method, for modifying at least one braking or powertrain application to individual road wheels of a vehicle in real time to improve lateral maneuverability in a vehicle having an electronic steering system that is operating, partially operating, invalidating, or already invalidating. The systems and methods may include modifying at least one braking or powertrain command to an individual road wheel in which vehicle instability is detected.

Description

Technical Field

[0001] The present disclosure relates generally to the fields of steering, braking, and powertrain systems. Background Art

[0002] A vehicle may include a steering system including an electric power steering system and a steer-by-wire system. Summary of the invention

[0003] A number of variations may include the method which may include modifying in real time at least one brake or powertrain application to one or more road wheels of a vehicle to improve lateral stability during a Brake-to-Steer function.

[0004] A number of variations may include the following method: The method may include increasing, decreasing or scaling at least one of an electronic brake system braking command or a powertrain system command when the brake steering is active. This may prevent vehicle instability or unintentional vehicle oversteering.

[0005] Vehicle instability may result in a total loss of vehicle control or create a safety hazard. A number of variations may include a method that reduces the likelihood of a loss of vehicle control by modifying at least one of a brake-steering brake or powertrain command based on a number of calculated, measured, or observed stability indicators. This improves not only vehicle safety, but also overall vehicle controllability with respect to brake-steering functionality.

[0006] Other illustrative variations within the scope of the present invention will become apparent from the detailed description provided hereinafter.It should be understood that the detailed description and specific examples, while disclosing variations of the present invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Selected examples of variations within the scope of the invention will become more fully understood from the detailed description and accompanying drawings, in which: Figure 1 An illustrative variation of a block diagram of a system and method for brake-steer lateral stability management is depicted; Figure 2 An illustrative variation of a block diagram of a system and method for brake-steer lateral stability management is depicted; Figure 3 An illustrative variation of a block diagram of a system and method for brake-steer lateral stability management is depicted; Figure 4An illustrative variation of a block diagram depicting a vehicle having a steer-by-wire system, wherein the vehicle also has the capability to perform brake-steer, and wherein the brake-steer functionality also incorporates a method of lateral stability management; and Figure 5 An illustrative variation of a block diagram of a vehicle having a connected power steering system is depicted, wherein the vehicle also has the capability to perform brake steer, and wherein the brake steer functionality also incorporates a method of lateral stability management.

[0008] The drawings are not necessarily drawn to scale, and certain features and certain views of the drawings may be shown exaggerated in scale or schematically in the interest of clarity and conciseness and should not be construed as limiting. DETAILED DESCRIPTION

[0009] The following description of the variations is merely illustrative in nature and is in no way intended to limit the scope of the invention, its application, or uses.

[0010] The vehicle typically includes a steering system, a braking system, and a powertrain system. The steering system may be a connected steering system with power steering (a steering system with a mechanical connection between the handwheel and the rack), or a steer-by-wire system (a steering system without a mechanical connection between the handwheel and the rack). The braking system may include: various devices for resisting the movement of the vehicle, including friction and electrical brakes. The powertrain system may include: various devices for propulsion, such as an internal combustion engine or an electric motor; and various devices for delivering torque, force or pressure from the propulsion system to individual tires, including transmissions, differentials, and torque vectoring differentials. The commands sent to the braking or powertrain system may include commanded torque, force, throttle or pedal position, current, voltage, pressure, or similar commands not previously stated. The load may include torque, force, pressure, or similar units not previously stated. The steering, braking, or powertrain system may contain electronic devices that allow them to send or receive signals and commands and convert the received commands into loads within the system or generated by the system and ultimately into loads at the tires. The driver of the vehicle controls the movement of the vehicle and may include a human driver or an automated driver. Systems such as steering systems may fail, which may include complete or partial failure or degradation.

[0011] In a wide range of maneuvers, the vehicle driver usually turns the hand wheel, and the electric power steering assist motor provides assistance to help the driver easily control the vehicle. However, power steering assist system components such as, but not limited to, a power rack or an electric motor or an actuator may fail. In this case, the driver may reach a very high hand wheel torque after applying the steering maneuver, and the driver may not be able to fully steer the vehicle due to the high hand wheel torque required for the steering input. This may increase the risk of vehicle accidents. At least one braking or powertrain application to individual wheels can be utilized to provide a unique and diverse support method using different actuators, which can help add lateral capabilities by adding a yaw torque from at least one of the braking or powertrain forces. This approach can be used for streamlined or degraded operating or semi-operating electric power steering or steer-by-wire systems to help the driver or automated controller in a wide range of maneuvers. When the driver or automated controller attempts to perform lateral maneuvers to turn or avoid obstacles, this can provide or enhance the lateral control capability of the vehicle and supplement the electric power steering system or steer-by-wire system.

[0012] When the electric power steering assist system or the steer-by-wire system includes components such as, but not limited to, a power rack, a motor, or an actuator that have failed, malfunctioned, or degraded, a brake-steer algorithm may be executed by an electronic processor and result in at least one brake or powertrain command to one or more wheels being generated as a function of vehicle state information. Alternatively, regenerative braking in individual wheels may be used to deploy a brake-steer function. Brake-steer may be a software function that provides at least one brake or powertrain command to one or more road wheels based on driver intent information, such as a driver handwheel torque or angle, and the at least one brake or powertrain command may be used in at least one brake or powertrain actuation system. The vehicle state information may include, for example, at least one of lateral acceleration, yaw rate, or, where available, steering sensor measurements, which may include, for example, at least one of a handwheel torque or angle. According to some variations, the brake-steer system may be controlled by a domain controller that is constructed and arranged to employ a brake-steer function when lateral maneuvers are in progress.

[0013] Braking steering can take driver intent input and output specific braking commands to individual tires that can be used to assist the driver in turning the vehicle the driver is operating. Braking steering braking commands can be calculated in such a way that sufficient braking force is provided on at least one road wheel to generate a yaw torque, which in turn generates a lateral force that supplements the lateral force induced by the driver's manual steering in a vehicle having a connected steering system with power steering. In a steer-by-wire system, if the rack system degrades, the driver may lose all lateral control of the vehicle. Braking steering braking commands can be calculated in such a way that sufficient braking force is provided on at least one road wheel to generate a yaw torque, which in turn generates a lateral force that achieves driver-limited lateral control of the vehicle initiated by the driver's steering. In a system being controlled by an automated driver, if there is a steering fault that degrades the ability of the electronic steering system to laterally steer the vehicle, the automated driver (autonomous or semi-autonomous driving system) can apply braking steering to generate a yaw torque, which in turn generates a lateral force that supplements the lateral force requested by the automated driver. Brake steering may also apply powertrain commands in response to driver or automated driver inputs to help the vehicle maintain the intended longitudinal velocity and generate more yaw moment on the vehicle to improve the lateral capability enhancement of brake steering. Brake steering may allow the vehicle to achieve a higher yaw rate during a wide range of maneuvers than it would have achieved with a degraded steering system without brake steering. Brake steering may help improve yaw rate, reduce driver effort, and improve vehicle lateral control. This may occur for a range of speeds and maneuvers. For example, when maneuvering at slow speeds in a parking lot, brake steering may provide a significant effort reduction for the driver.

[0014] In some driving scenarios, brake steer may result in unintentional vehicle oversteering or excessive vehicle yaw rate. An example of when this scenario may occur would be when the driver exceeds the surface friction limit while turning. Existing systems and methods developed to mitigate vehicle stability issues may not function effectively during brake steer operations for a variety of reasons.

[0015] Electronic stability control systems typically require a steering wheel angle signal to function, which is important because in some use cases of brake-steer implementations, a steering wheel angle signal may not be available, which means that brake-steer may not be able to rely on existing vehicle stability control systems to maintain stability. If hand-wheel angle information is available, existing vehicle stability control systems may not be sufficient to prevent brake-steer from oversteering the vehicle because they do not modify at least one of the brake-steer braking or powertrain commands. An advantage of some variations of the disclosed systems and methods is that stability is ensured for scenarios involving loss of brake-steer and electric power steering systems because some variations of the disclosed systems and methods can rely on several stability indicators without having to use hand-wheel angle. However, if hand-wheel or steering angle data is available, it can be used.

[0016] Electronic brake force distribution lacks the ability to control powertrain torque command and is only effective when negative tire slip is taken into account. An advantage of some embodiments of the disclosed system and method (brake steering regulation based on stability indicators and in particular brake steering regulation based on wheel speed) is more robust instability detection when powertrain torque is being applied, given its ability to control powertrain torque command. Additionally, an advantage of some embodiments of the disclosed system is that the disclosed system can act on positive and negative tire slip in addition to several other stability indicators.

[0017] Anti-lock braking systems (ABS) fail to monitor or account for wheel speeds and wheel slip ratios at all corners of a vehicle because they modulate primarily based on wheel slip of one tire rather than based on wheel slip relative to different tires. ABS also lacks the ability to control powertrain torque commands. Brake steering with stability indicator scaling can act on positive and negative tire slip. An advantage of some variations of the disclosed systems and methods, such as brake steering modulation based on stability indicators, is more robust instability detection when at least one brake or powertrain command is being applied to an individual wheel because it can take into account positive and negative tire slip as well as several other stability indicators. In addition, brake steering modulation based on stability indicators has the ability to control powertrain torque commands, unlike typical ABS functionality.

[0018] The traction control system lacks the ability to control the brake steer brake command. The traction control system also lacks the ability to act on negative tire slip. An advantage of some embodiments of the disclosed systems and methods (brake steer adjustment based on stability indicators) is that wheel speeds or slip ratios and their relationship to each other can be monitored for all corners of the vehicle, in addition to other stability indicators. Therefore, the brake steer stability method, system or computer product described herein, which may include an algorithm, is more robust in detecting instability when at least one brake or powertrain command is being applied to an individual wheel.

[0019] Stability indicator based brake steering regulation can continuously monitor vehicle stability in all driving conditions and prevent the vehicle from losing stability in situations where brake steering application causes the vehicle to oversteer. The system and method can be tuned to act when vehicle oversteering characteristics are detected based on individual or multiple stability indicators.

[0020] The stability indicator may include a plurality of stability detection metrics such as, but not limited to, yaw rate error, differential wheel slip, output from an electronic power steering (EPS), electronic stability control (ESC), traction control system (TCS), or anti-lock braking system (ABS), or a measured or observed road surface friction (mu) indicator. A plurality of variations may include a method, system, or computer medium having executable instructions for performing the following operations: scaling, reducing, or increasing at least one brake-steer braking or brake-steer powertrain command in the event that the brake-steer command results in vehicle instability or unintentional vehicle oversteering, particularly in low surface mu driving scenarios but not limited thereto.

[0021] A number of variations may include a brake steering stability method, system, or computer product that may include a medium having instructions executable by an electronic processor for performing the following operations: modifying in real time at least one brake or powertrain application to an individual road wheel of a vehicle to improve lateral stability during a brake steering function. A number of variations may include a computer product that may include instructions for implementing the various functions described herein, such as algorithms stored on the medium and executable by the electronic processor. A brake steering stability module or controller receives a signal from the vehicle, the brake steering stability module or controller may include instructions such as algorithms stored on the medium and executable by the electronic processor, the signal may include but is not limited to at least one of yaw rate, vehicle speed, vehicle acceleration, steering wheel angle, hand wheel torque, wheel speed, or tire slip. The brake steering stability module or controller uses these inputs to calculate one or more stability indicators. The brake steering stability module or controller may also receive externally calculated stability indicators including, but not limited to, road surface mu or activation flags from an external system such as electronic stability control (ESC), anti-lock braking system (ABS), traction control system (TCS), or electronic brake-force distribution (EBD).

[0022] The stability indicator calculated by the brake steering stability module or controller may include a yaw rate error. The yaw rate error may be calculated by comparing an estimated or predicted yaw rate to a measured or calculated vehicle yaw rate. The estimated yaw rate may be calculated using at least one of lateral acceleration, vehicle speed, steering wheel angle, hand wheel torque, or individual wheel speed.

[0023] The stability indicator calculated by the brake steering stability module or controller may include differential wheel slip. To calculate differential wheel slip, a first individual tire longitudinal slip may be calculated. The wheel speed signal and the estimated reference vehicle longitudinal speed may be used to calculate the longitudinal tire slip at each corner of the vehicle. An iteration of this may also use the yaw rate and vehicle track width to better estimate the slip at each corner. Individual tire slip may also be calculated externally and transmitted to the brake steering stability module or controller.

[0024] From the individual tire longitudinal slips, several types of differential wheel slip can be calculated, for example: the absolute value of the difference between the left and right tire slips for each axle (which is related to the yaw moment applied on each axle by the longitudinal tire forces); or the sum of the absolute values ​​of the difference between the left and right tire slips for each axle (which is related to the yaw moment applied on the entire vehicle by the longitudinal tire forces); or (for rear wheel drive) the difference between the outer rear tire slip and the outer front tire slip; or (for front wheel drive) the difference between the outer front tire slip and the outer rear tire slip.

[0025] Each stability indicator may be compared to its stability indicator threshold. Stability indicator thresholds may include, but are not limited to, thresholds, tolerances, or expected values. These stability indicators and stability indicator thresholds may be used individually or in combination. When the stability indicators are within their thresholds, at least one of the brake steering braking or brake steering powertrain commands is allowed to be sent to the vehicle unchanged to assist in lateral control for normal brake steering operation. When the stability indicators are outside their thresholds, the brake steering stability module or controller modulates at least one of the brake or powertrain commands to prevent excessive vehicle instability. The modulation may be achieved by various means, including, but not limited to: calculating a new command by multiplying or dividing the original command by a scalar; or calculating a new command by adding or subtracting an offset from the original command. These scalars or offsets may be predetermined or dynamically calculated based on the difference between the stability indicator and their thresholds. The brake steering stability module or controller may also output its internal calculations and / or states for downstream use. Further details and other variations are described below, including methods, systems, computer media including instructions stored thereon and executable by an electronic processor, and functions.

[0026] As a non-limiting example, the brake steering adjustment based on the stability indicator may include a brake steering adjustment based on a yaw rate error to improve brake steering performance and vehicle safety. The estimated yaw rate may be calculated using lateral acceleration and vehicle speed. The estimated yaw rate may be calculated using wheel speed. The estimated yaw rate may be calculated using vehicle speed and steering wheel angle. The estimated yaw rate may be calculated using any combination of previously defined methods. The estimated yaw rate may be compared with a measured or calculated vehicle yaw rate to calculate a yaw rate error. Using the error calculation and depending on the magnitude and direction of the yaw rate error, the system and method may adjust, modify, update, adjust, or create at least one new brake or powertrain command to prevent further vehicle oversteering. When the yaw rate error stability indicator is within an acceptable threshold range, for normal brake steering operation, at least one of a brake steering brake or a brake steering powertrain command is allowed to be sent to the vehicle without stability modification to assist lateral control.

[0027] As a non-limiting example, the brake steering adjustment based on the stability indicator may include brake steering adjustment based on wheel speed to improve brake steering performance and vehicle safety. The system, method or product may use the measured wheel speed signal and the longitudinal speed of the vehicle to calculate the longitudinal tire slip for each corner of the car. Based on the slip ratio, several stability indicators may be calculated. For example: the absolute value of the difference between the left and right tire slip for each axle; or the sum of the absolute values ​​of the difference between the left and right tire slip for each axle; or in the case of a rear-wheel drive vehicle, the difference between the outer rear tire slip and the outer front tire slip; or in the case of a front-wheel drive vehicle, the difference between the outer front tire slip and the outer rear tire slip. These slip ratio-based stability indicators may be used individually or in combination. According to the disclosed system and method for brake steering adjustment based on stability indicators, at least one of the brake steering brake or brake steering powertrain command may be modulated to prevent excessive vehicle instability when these stability indicators are outside their acceptable threshold ranges. At least one of a brake-to-steer braking or a brake-to-steer powertrain command is allowed to be sent to the vehicle without modification to assist in lateral control when the slip ratio-based stability indicator is within an acceptable threshold range.

[0028] In the case of a steer-by-wire vehicle, it is assumed that a steering wheel based steering angle sensor (SAS) or some other form of SAS is able to interpret the driver intent. The steering angle can be used to predict the intended vehicle yaw rate. A yaw rate error will be calculated by comparing the predicted intended vehicle yaw rate with the measured vehicle yaw rate. Stability mitigation strategies similar to those described in the above paragraphs can be implemented in a steer-by-wire system. A change in at least one brake-steer brake or brake-steer powertrain command can be different for a steer-by-wire vehicle use case.

[0029] Figure 1 An illustrative variation of a block diagram of a system and method 100 for brake-steer lateral stability management based on a stability indicator is depicted. Figure 1Only exemplary manners in which the method and system may be accomplished are depicted. The system and method may include receiving vehicle data from onboard vehicle systems and sensors, such as vehicle speed 104, lateral acceleration 106, and vehicle yaw rate 108. The stability indicator based command scaling algorithm 110 may include estimating a yaw rate 118 based on the vehicle speed 104 and the lateral acceleration 106. A yaw rate error 120 may be calculated based on the estimated yaw rate 118 and the measured vehicle yaw rate 108. The calculated yaw rate error 120 may be used in a scalar calculation 122 based on the yaw rate error based on the measured vehicle speed 104. The scalar calculation 122 based on the yaw rate error may communicate a scalar value 124 to at least one brake or powertrain command modifier 114. Alternatively, the scalar calculation 122 based on the yaw rate error may communicate a reduction value to at least one of the brake-steering brake or brake-steering powertrain command modifiers 114. The system and method may include transmitting at least one of the brake-steer braking or brake-steer powertrain command 102 in the pre-expanded state 112 to at least one of the brake-steer braking or powertrain command modifications 114. At least one of the brake-steer braking or brake-steer powertrain command modifiers 114 may determine at least one of a modified brake-steer braking or brake-steer powertrain command 126 based on the pre-expanded brake or powertrain commands 102, 112 and at least one of a scalar calculation 122 based on a yaw rate error and a scalar value or reduced value 124. At least one of the modified brake-steer braking or brake-steer powertrain command 126 may be transmitted to a domain controller (not shown) to send at least one of the modified brake or powertrain commands to at least one brake or powertrain actuator to reduce lateral instability in the vehicle during brake-steer. In a number of variations, the modifier value may be based on, but is not limited to, at least one of: a two-dimensional table of yaw rate error versus speed; a one-dimensional table of yaw rate error; a single yaw rate error value; a two-dimensional table of yaw rate error versus wheel speed; a two-dimensional table of yaw rate error versus yaw rate; a three-dimensional table of yaw rate error, yaw rate, and wheel speed; or other numerical calculations.

[0030] Figure 2An illustrative variation of a block diagram of a system and method 100 for brake-steer lateral stability management based on stability indicators is depicted. The system can use measured wheel speed signals 202 and vehicle speed 104 to calculate a longitudinal tire slip ratio 204 for each corner of the vehicle. Based on the longitudinal tire slip ratio 204, a stability indicator 206a, 206b, or 206c that serves as an indication of vehicle stability can be calculated. A scalar calculation 208 based on the stability indicator can receive the stability indicators 206a, 206b, and 206c and can use them individually or in combination to calculate a wheel speed-based scalar 210. The system and method can include: transmitting at least one of the brake-steer braking or brake-steer powertrain command 102 in the pre-expansion state 112 to at least one of the brake or powertrain command modifiers 114. At least one of the brake-steer braking or brake-steer powertrain command modifiers 114 may receive a wheel speed-based scalar 210 based on the stability indicator 206a, 206b, or 206c and a stability indicator-based scalar calculation 208 determined via the stability indicator command scaling algorithm 110. The brake-steer braking or brake-steer powertrain command modifier 114 may determine at least one of the modified brake-steer braking or brake-steer powertrain commands 126 based on the pre-scaled brake or powertrain commands 102, 112 and at least one of the scalar calculation 208 and the scalar value or reduced value 210. Note that Figure 2 Only an illustrative example of a stability indicator command scaling algorithm 110 utilizing the measured wheel speed signals 202, the calculated longitudinal tire slip ratio 204 for each corner of the vehicle, and the stability indicator 206a, 206b, or 206c is depicted. At least one of the modified brake-steer braking or brake-steer powertrain commands 126 may be communicated to a domain controller (not shown) to send at least one of the modified brake or powertrain commands to at least one brake or powertrain actuator to reduce lateral instability in the vehicle during brake-steer.

[0031] Figure 3A method and system 300 is illustrated, which may include receiving an original brake steering command 302 by a decision module 304, which outputs 320 the original brake steering command or a modified brake steering command to at least one brake or powertrain system. A plurality of vehicle signals 306 may be received by a module 308, which may calculate or receive a stability indicator and output 310 the stability indicator, and the vehicle signals may also be received by a module 312, which may compare at least one stability indicator to a stability indicator threshold. The module 312 may receive the stability indicator calculated or received by the module 308. The module 312 may compare the stability indicator to the stability indicator threshold, and if the stability indicator exceeds the limit of the stability indicator threshold range, the module 312 may output 314 data related to the stability indicator and the stability indicator threshold, which may be received by a module 316. The module 316 may calculate at least one brake or powertrain command modulation and may output 318 the calculated modulation to the module 304. Module 304 may receive the calculated modulation, and modify at least one received brake or powertrain command by the calculated modulation to provide at least one modified brake or powertrain command, and output 320 the at least one modified brake or powertrain command to at least one brake or powertrain system.

[0032] A number of variations may include a computer readable medium, which may be non-transitory, having instructions written thereon and executable by an electronic processor to provide functionality including: calculating or receiving a vehicle stability indicator; comparing the stability indicator to a stability indicator threshold; and if the stability indicator is outside the limits of the stability indicator threshold range, calculating modulation of at least one brake-steering braking or brake-steering powertrain command to provide at least one modified brake or powertrain command; and outputting at least one modified brake or powertrain command. At least one of the modified brake or powertrain commands may be received by at least one brake or powertrain system.

[0033] Figure 4 A vehicle with steer-by-wire functionality and a system for implementing the methods described herein are illustrated. Figure 5 A vehicle having a mechanical steering linkage and a system for implementing the methods described herein are illustrated. Figure 4 and 5 The components and systems are interchangeable as long as Figure 4 The vehicle retains the steer-by-wire function and Figure 5 The vehicle retains the mechanical steering linkage.

[0034] Figure 4 Depicted are illustrative variations of various portions of a vehicle equipped with hardware sufficient to implement at least some of the systems and methods described herein. All sensors depicted in the illustrative variations are illustrative, and thus, the sensed inputs may come from various other vehicle locations or vehicle sensors, as long as they provide similar sensing functions. The vehicle 750 may include a controller 712 constructed and arranged to provide a brake-steer function in the vehicle 750. The controller 712 may be in operable communication with a steer-by-wire system 715 and an electronic brake system 716. The steer-by-wire system 715 may be comprised of a handwheel actuator 746 and a roadwheel actuator 714. The steer-by-wire system 715 may be constructed and arranged to turn at least one roadwheel 742. The electronic brake system 716 may apply a braking force or braking torque 720 to the determined appropriate roadwheel 742. The driver can utilize a hand wheel 744 including at least one hand wheel actuator 746 to provide driver input 734 for lateral movement and send steering commands to the steer-by-wire system 715 and the road wheel actuator 714. The electronic brake system 716 can be in operable communication with the controller 712 and a driver brake input system 752 (such as a brake pedal system) to receive the driver brake input. According to some variations, the hand wheel actuator 746 can be in operable communication with the controller 712, the steer-by-wire road wheel actuator 714, or the electronic brake system 716. In some variations, the hand wheel actuator 746 can be disconnected from or in a failed state 748, or cannot communicate with the steer-by-wire road wheel actuator 714. In this variation, the hand wheel actuator 746 can transmit the steering command to the controller 712, and the controller 712 can receive the steer-by-wire system 715 health status information. In the event that the controller 712 has received steer-by-wire system 715 information indicating a failure 748 of the steer-by-wire system 715 or a failure of the road wheel actuator 714, the controller 712 may convert the steering command from the hand wheel actuator 746 into a braking force or braking torque command to be transmitted to the electronic braking system 716. The electronic braking system 716 may apply the braking force or braking torque 720 to the appropriate road wheel 742 determined to achieve lateral movement of the vehicle as input 734 by the driver via the hand wheel 744. The controller 712 may also send powertrain commands to the powertrain system 708. The controller 712 and any other controllers (e.g., controller 768) may be provided to implement one or more functions described herein and may include a processor 760, a memory 762, wherein instructions 764 stored in the memory 762 may be executed by the processor 760.

[0035] Reference now Figure 5, shows an illustrative variation of a vehicle equipped with hardware that allows the vehicle to implement at least some of the methods disclosed herein. All sensors depicted in the illustrative variations are illustrative, and thus, the sensed inputs can come from various other vehicle locations or vehicle sensors as long as they provide similar sensing functions. Vehicle 801 can be equipped with a road wheel 802 and a hand wheel 803, the hand wheel 803 being used to tune the road wheel 802 via a pinion 804, and the pinion 804 meshing with a rack 805 constructed and arranged to turn the road wheel 802. In the illustrative variation shown, the hand wheel 803 can be equipped with a hand wheel torque sensor 806 and a hand wheel angle sensor 807, so that any turning of the hand wheel can generate sensor data that can be transmitted to or accessed by a controller 808. Controller 808 can provide all other functions described herein, including brake steering, brake steering stability, wire steering control, powertrain control, brake control, control of vehicle systems, or one or more other controllers can be provided to accomplish the same thing. Although controller 808 is shown as vehicle-mounted in this illustrative variation, the controller can also be located somewhere other than the vehicle and communicate with the sensor or vehicle wirelessly. Pinion 804 can be equipped with a pinion torque sensor 809 so that any turning of the pinion can be observed by controller 808 or transmitted to controller 808 and utilized by the method described herein. In the illustrative variation shown, rack 805 can be equipped with a rack force sensor 810 so that any rack force detected during driving can be observed by controller 808 or transmitted to controller 808 and utilized by the method described herein. Vehicle can have: steering shaft 814, connecting the steering wheel or steering interface 803 to pinion 804. An electric steering assist or hydraulic power steering device 836 may be connected to shaft 814 to assist the driver in steering the vehicle's road wheels by reducing the force or torque that the driver would need to apply to the steering wheel or steering interface 803 if the power steering device 836 were not present. Also shown in this illustrative variation, the road wheels 802 may be equipped with road wheel sensors so that any road wheel data detected during driving may be observed by or transmitted to the controller 808 and utilized by the methods described herein. Additionally, in the illustrative variation shown, the brake 812 is located near the road wheels 802. The controller 808 and any other controllers (e.g., controller 818) may be provided to implement one or more functions described herein and may include a processor 820, a memory 822, wherein instructions 824 stored in the memory 822 may be executed by the processor 820 to determine whether the hand wheel angle sensor 807 has failed or whether the pinion 804, the rack 805, the pinion sensor 809, or the rack sensor 810 has failed.Furthermore, the instructions 824 stored in the memory 822 may be executed by the processor 820 to implement any of the methods or achieve any functionality described herein.

[0036] The modules and controllers described herein may include software, hardware, or a computing device including: a non-transitory computer-readable medium having instructions stored thereon, such as, but not limited to, a memory; and a processor for executing instructions for performing the actions, steps, methods, and functions described herein. Multiple modules and controllers and their associated actions, steps, methods, and functions may be included in or implemented by one or more computing devices.

[0037] The following description of variants only illustrates the parts, elements, actions, products and methods that are considered to be within the scope of the present invention, and is not intended in any way to limit such scope by specifically disclosed or unexplicitly stated content. The parts, elements, actions, products and methods as described herein may be combined and rearranged in a manner other than the manner explicitly described herein, and are still considered to be within the scope of the present invention.

[0038] Variant 1 may include a computer-readable medium comprising: a non-volatile memory having instructions stored thereon executable by an electronic processor, the instructions, when executed by the electronic processor, performing the following functions including the following: receiving or calculating at least one stability indicator, wherein the received at least one stability indicator includes at least one of vehicle speed, lateral acceleration, vehicle yaw rate, steering wheel angle, steering wheel torque, speed, wheel speed, or yaw rate, and wherein calculating at least one stability indicator includes calculating a yaw rate; calculating an estimated yaw rate based on at least one of the vehicle speed, wheel speed, or lateral acceleration; calculating a yaw rate error based on at least one of the estimated yaw rate or the measured vehicle yaw rate; determining a braking command modifier value based on at least one of the measured vehicle speed or the yaw rate error; modifying at least one braking command based on the braking command modifier value to provide a modified braking command; transmitting the modified braking command to a brake steering system.

[0039] Variation 2 may include a computer readable medium as set forth in Variation 1 further comprising: determining a modified powertrain modifier value based on at least one of the measured vehicle speed or the yaw rate error; and modifying at least one powertrain command based on the powertrain command modifier value.

[0040] Variation 3 may include a computer readable medium as set forth in Variation 1 wherein the brake command modifier value is a scalar value.

[0041] Variation 4 may include a computer readable medium as set forth in Variation 2 wherein the powertrain command modifier value is a scalar value.

[0042] Variation 5 may include a computer readable medium as set forth in Variation 1 wherein the brake command modifier value is a reduced value.

[0043] Variation 6 may include a computer readable medium as set forth in Variation 2 wherein the powertrain command modifier value is a reduced value.

[0044] Variation 7 may include a computer-readable medium as set forth in Variation 1 wherein determining a brake command modifier value based on at least one of the measured vehicle speed or the yaw rate error comprises utilizing at least one of: a two-dimensional yaw rate error versus speed table; a one-dimensional yaw rate error table; a single yaw rate error value; a two-dimensional yaw rate error versus wheel speed table; a two-dimensional yaw rate error versus yaw rate table; a three-dimensional table of yaw rate error, yaw rate, and wheel speed; or other numerical calculations.

[0045] Variation 8 may include a computer readable medium as set forth in Variation 1 further comprising transmitting a brake steering command in a pre-expanded state to a brake steering command modifier prior to modifying at least one brake command based on the brake command modifier value.

[0046] Variant 9 may include a computer program product comprising instructions executable by an electronic processor to perform actions comprising: determining that a steering maneuver is in progress in a vehicle; receiving vehicle data comprising at least one of vehicle feedback information or actuator feedback information; calculating a stability indicator threshold; calculating a stability indicator; determining a difference between the stability indicator and the stability indicator threshold; comparing the stability indicator threshold and the stability indicator; and generating at least one change to a brake steering actuator command based on the comparison.

[0047] Variation 10 may include a computer readable medium as set forth in Variation 9 further comprising determining a modified brake steering command modifier value based on the comparison, and wherein generating at least one modification to the brake steering actuator command is based on the brake steering command modifier value.

[0048] Variation 11 may include a computer readable medium as set forth in Variation 9 further comprising generating at least one modification to a powertrain command based on the comparison.

[0049] Variation 12 may include a computer readable medium as set forth in Variation 11 further comprising determining a modified powertrain modifier value based on the comparison, and wherein generating the at least one modification to the powertrain command is based on the powertrain command modifier value.

[0050] Variation 13 may include a computer readable medium as set forth in Variation 10 wherein the brake command modifier value is a scalar value.

[0051] Variation 14 may include a computer readable medium as set forth in Variation 12 wherein the powertrain command modifier value is a scalar value.

[0052] Variation 15 may include a computer readable medium as set forth in Variation 10 wherein the brake command modifier value is a reduced value.

[0053] Variation 16 may include a computer readable medium as set forth in Variation 12 wherein the powertrain command modifier value is a reduced value.

[0054] Variation 17 may include a computer readable medium as set forth in Variation 10 wherein determining a brake command modifier value based on the comparison comprises utilizing at least one of: a two dimensional yaw rate error versus speed table; a one dimensional yaw rate error table; a single yaw rate error value; a two dimensional yaw rate error versus wheel speed table; a two dimensional yaw rate error versus yaw rate table; a three dimensional table of yaw rate error, yaw rate, and wheel speed; or other numerical calculations.

[0055] Variation 18 may include a computer readable medium as set forth in Variation 9 further comprising transmitting a brake steering command in a pre-expanded state to a brake steering command modifier prior to modifying the at least one brake command based on the brake command modifier value.

[0056] Variant 19 may include a computer-readable medium, which may be non-transitory, having instructions written thereon, the instructions being stored thereon and executable by an electronic processor to provide functionality including: determining whether a brake-steer system is steering a vehicle; and if so, calculating or receiving a vehicle stability indicator; comparing the stability indicator to a stability indicator threshold; and if the stability indicator exceeds the limits of a stability indicator threshold range, calculating a modulation of at least one of a braking or powertrain command to provide a modified brake-steer braking command or a brake-steer powertrain command; and outputting a modified brake-steer braking command or a brake-steer powertrain command.

[0057] Variation 20 may include a computer readable medium as set forth in Variation 19 wherein a modulation of at least one of a calculated braking or powertrain command is based on at least one of a measured vehicle speed or the yaw rate error; and the modified braking or powertrain command is based on a braking command modifier value or a powertrain command modifier value.

[0058] Variation 21 may include a computer readable medium as set forth in Variation 20 wherein the brake command modifier value is a scalar value.

[0059] Variation 22 may include a computer readable medium as set forth in Variation 20 wherein the powertrain command modifier value is a scalar value.

[0060] Variation 23 may include a computer readable medium as set forth in Variation 20 wherein the brake command modifier value is a reduced value.

[0061] Variation 24 may include a computer readable medium as set forth in Variation 20 wherein the powertrain command modifier value is a reduced value.

[0062] Variation 25 may include a computer readable medium as set forth in Variation 20 wherein the braking command modifier value based on at least one of the measured vehicle speed or the yaw rate error comprises utilizing at least one of: a two dimensional yaw rate error versus speed table; a one dimensional yaw rate error table; a single yaw rate error value; a two dimensional yaw rate error versus wheel speed table; a two dimensional yaw rate error versus yaw rate table; a three dimensional table of yaw rate error, yaw rate, and wheel speed; or other numerical calculations.

[0063] Variation 26 may include a computer readable medium as set forth in Variation 20 further comprising transmitting a brake steering command in a pre-expanded state to a brake steering command modifier prior to providing a modified brake command based on the brake command modifier value.

[0064] Variant 27 may include a method comprising: receiving or calculating at least one stability indicator, wherein the received at least one stability indicator includes at least one of vehicle speed, lateral acceleration, vehicle yaw rate, steering wheel angle, steering wheel torque, speed, wheel speed, or yaw rate, and wherein calculating the at least one stability indicator calculates a yaw rate; calculating an estimated yaw rate based on at least one of the vehicle speed, wheel speed, or lateral acceleration; calculating a yaw rate error based on the estimated yaw rate or at least one of the measured vehicle yaw rate; determining a braking command modifier value based on at least one of the measured vehicle speed or the yaw rate error; modifying at least one braking command based on the braking command modifier value to provide a modified braking command; and transmitting the modified braking command to a brake steering system.

[0065] Variation 28 may include a method as set forth in Variation 27 further comprising: determining a modified powertrain modifier value based on at least one of the measured vehicle speed or the yaw rate error; and modifying at least one powertrain command based on the powertrain command modifier value.

[0066] Variation 29 may include a method as set forth in Variation 27 wherein the brake command modifier value is a scalar value.

[0067] Variation 30 may include a method as set forth in Variation 28 wherein the powertrain command modifier value is a scalar value.

[0068] Variation 31 may include a method as set forth in Variation 27 wherein the brake command modifier value is a reduced value.

[0069] Variation 32 may include a method as set forth in Variation 28 wherein the powertrain command modifier value is a reduced value.

[0070] Variation 33 may include a method as described in Variation 27 wherein determining a brake command modifier value based on at least one of the measured vehicle speed or the yaw rate error comprises utilizing at least one of: a two-dimensional yaw rate error versus speed table; a one-dimensional yaw rate error table; a single yaw rate error value; a two-dimensional yaw rate error versus wheel speed table; a two-dimensional yaw rate error versus yaw rate table; a three-dimensional table of yaw rate error, yaw rate, and wheel speed; or other numerical calculations.

[0071] Variation 34 may include a method as set forth in Variation 27 further comprising transmitting a brake steering command in a pre-expanded state to a brake steering command modifier prior to modifying the at least one brake command based on the brake command modifier value.

[0072] Variant 35 may include a method comprising: determining whether a brake-steer system is turning a vehicle; and if so, calculating or receiving a vehicle stability indicator; comparing the stability indicator to a stability indicator threshold; and if the stability indicator exceeds the limit of the stability indicator threshold range, calculating a modulation of at least one of a braking or powertrain command to provide at least one of a modified brake-steer braking command or a brake-steer powertrain command; and outputting at least one of a modified brake-steer braking command or a brake-steer powertrain command.

[0073] Variation 36 may include a method as set forth in Variation 35 further comprising receiving the outputted modified braking command by a braking system or receiving the outputted modified powertrain command by a powertrain system.

[0074] Variation 37 may include a method as set forth in Variation 35 wherein calculating a modulation of at least one of a braking or powertrain command is based on at least one of a measured vehicle speed or the yaw rate error; and the modified braking or powertrain command is based on a braking command modifier value or a powertrain command modifier value.

[0075] Variation 38 may include a method as set forth in Variation 37 wherein the brake command modifier value is a scalar value.

[0076] Variation 39 may include a method as set forth in Variation 37 wherein the powertrain command modifier value is a scalar value.

[0077] Variation 40 may include a method as set forth in Variation 37 wherein the brake command modifier value is a reduced value.

[0078] Variation 41 may include a method as set forth in Variation 37 wherein the powertrain command modifier value is a reduced value.

[0079] Variation 42 may include a method as set forth in Variation 37 wherein the braking command modifier value based on at least one of the measured vehicle speed or the yaw rate error comprises utilizing at least one of: a two-dimensional yaw rate error versus speed table; a one-dimensional yaw rate error table; a single yaw rate error value; a two-dimensional yaw rate error versus wheel speed table; a two-dimensional yaw rate error versus yaw rate table; a three-dimensional table of yaw rate error, yaw rate, and wheel speed; or other numerical calculations.

[0080] Variation 43 may include a method as set forth in Variation 37 further comprising transmitting a brake steering command in a pre-expanded state to a brake steering command modifier prior to providing a modified brake command based on the brake command modifier value.

[0081] Variation 44 may include a method as set forth in Variation 35 wherein the calculated modulation is a scalar value.

[0082] Variation 45 may include a method comprising reducing a likelihood of loss of vehicle control by modifying at least one of a brake-steer braking command or a brake-steer powertrain command based on a plurality of calculated, measured, or observed stability indicators.

[0083] Variant 46 may include a method as described in Variant 45, further comprising: comparing the stability indicator to a stability indicator threshold; and if the stability indicator exceeds the limit of the stability indicator threshold range, then calculating a modulation of at least one of the braking or powertrain commands to provide a modified braking-steering braking command or at least one of the powertrain commands; and outputting at least one of the modified braking-steering braking command or the braking-steering powertrain command.

[0084] Variation 47 may include a method as set forth in Variation 46 further comprising receiving the outputted modified braking command by a braking system or receiving the outputted modified powertrain command by a powertrain system.

[0085] Variation 48 may include a method as set forth in Variation 46 wherein calculating a modulation of at least one of a braking or powertrain command is based on at least one of a measured vehicle speed or the yaw rate error; and the modified braking or powertrain command is based on a braking command modifier value or a powertrain command modifier value.

[0086] Variation 49 may include a method as set forth in Variation 48 wherein the brake command modifier value is a scalar value.

[0087] Variation 50 may include a method as set forth in Variation 48 wherein the powertrain command modifier value is a scalar value.

[0088] Variation 51 may include a method as set forth in Variation 48 wherein the brake command modifier value is a reduced value.

[0089] Variation 52 may include a method as set forth in Variation 48 wherein the powertrain command modifier value is a reduced value.

[0090] Variation 53 may include a method as set forth in Variation 48 wherein the braking command modifier value based on at least one of the measured vehicle speed or the yaw rate error comprises utilizing at least one of: a two-dimensional yaw rate error versus speed table; a one-dimensional yaw rate error table; a single yaw rate error value; a two-dimensional yaw rate error versus wheel speed table; a two-dimensional yaw rate error versus yaw rate table; a three-dimensional table of yaw rate error, yaw rate, and wheel speed; or other numerical calculations.

[0091] Variation 54 may include a method as set forth in Variation 48 further comprising transmitting a brake steering command in a pre-expanded state to a brake steering command modifier prior to providing a modified brake command based on the brake command modifier value.

[0092] Variation 55 may include a method as set forth in Variation 46 wherein the calculated modulation is a scalar value.

[0093] Variant 56 may include a non-transitory computer readable medium having instructions written thereon that are executable by an electronic processor to provide functionality including: receiving wheel speed and vehicle speed data and using the wheel speed and speed data to calculate a stability indicator; using at least one of the stability indicators to calculate a scalar based on the stability indicator; transmitting at least one of a brake-steer-brake command or a powertrain command in a pre-expansion state to at least one of a brake or powertrain command modifier; transmitting a scalar based on the stability indicator to at least one of a brake-steer-brake or a brake-steer-powertrain command modifier and generating at least one of a modified brake-steer-brake command or a modified brake-steer-powertrain command.

[0094] Variation 57 may include a non-transitory computer readable medium as set forth in Variation 56 further comprising calculating a tire slip ratio for each tire at a corner of the vehicle using the wheel speed and vehicle speed data; and wherein calculating the stability indicator comprises using the wheel slip ratios.

[0095] Variation 58 may include a non-transitory computer readable medium as described in Variation 56, wherein the functions further comprise: transmitting at least one of a brake-steering braking command or a powertrain command in a pre-expanded state or transmitting at least one of a modified brake-steering braking command or a modified powertrain command to a domain controller to reduce lateral instability in the vehicle during a brake-steering maneuver.

[0096] Variation 59 may include a non-transitory computer readable medium as set forth in Variation 56 wherein the brake command modifier value is a scalar value.

[0097] Variation 60 may include a non-transitory computer readable medium as set forth in Variation 56 wherein the command modifier generates the powertrain command modifier value as a scalar value.

[0098] Variation 61 may include a non-transitory computer readable medium as set forth in Variation 56 wherein the command modifier generates the brake command modifier value as a reduced value.

[0099] Variation 62 may include a non-transitory computer readable medium as set forth in Variation 56 wherein the command modifier generates the powertrain command modifier value as a reduced value.

[0100] The foregoing description of selected variations within the scope of the present invention is merely illustrative in nature, and thus, variations or modifications thereof are not to be regarded as a departure from the spirit and scope of the present invention.

Claims

1. A method comprising: receiving or calculating at least one stability indicator, wherein the received at least one stability indicator comprises at least one of vehicle speed, lateral acceleration, vehicle yaw rate, steering wheel angle, steering wheel torque, speed, wheel speed, or yaw rate, and wherein calculating the at least one stability indicator calculates the yaw rate; calculating an estimated yaw rate based on at least one of vehicle speed, wheel speed, or lateral acceleration; calculating a yaw rate error based on at least one of the estimated yaw rate or the measured vehicle yaw rate; determining a brake command modifier value based on at least one of a measured vehicle speed or the yaw rate error; modifying at least one braking command based on the braking command modifier value to provide a modified braking command; The modified brake command is transmitted to the brake steering system.

2. The method of claim 1, further comprising: determining a modified powertrain modifier value based on at least one of the measured vehicle speed or the yaw rate error; and modifying at least one powertrain command based on the powertrain command modifier value. The method of claim 1 , wherein the brake command modifier value is a scalar value. The method of claim 2 , wherein the powertrain command modifier value is a scalar value. The method of claim 1 , wherein the brake command modifier value is a reduced value. The method of claim 2 , wherein the powertrain command modifier value is a reduced value.

7. The method of claim 1 , wherein determining a brake command modifier value based on at least one of the measured vehicle speed or the yaw rate error comprises utilizing at least one of: a two-dimensional yaw rate error versus speed table; a one-dimensional yaw rate error table; a single yaw rate error value; a two-dimensional yaw rate error versus wheel speed table; a two-dimensional yaw rate error versus yaw rate table; a three-dimensional table of yaw rate error, yaw rate, and wheel speed; or other numerical calculations.

8. The method of claim 1, further comprising: Prior to modifying at least one brake command based on the brake command modifier value, a brake steering command in a pre-expanded state is transmitted to a brake steering command modifier.

9. A method comprising: determining whether the brake-steering system is steering the vehicle; and if so, comparing the indicator to a stability indicator threshold; and if the stability indicator exceeds a limit of a stability indicator threshold range, calculating a modulation of at least one of a brake or powertrain command to provide at least one of a modified brake-steer brake command or a brake-steer powertrain command; and outputting at least one of a modified brake-steer brake command or a brake-steer powertrain command.

10. The method of claim 9, further comprising: The output modified braking command is received by the braking system or the output modified powertrain command is received by the powertrain system.

11. The method of claim 9, wherein calculating a modulation of at least one of a braking or powertrain command is based on at least one of a measured vehicle speed or the yaw rate error; and the modified braking or powertrain command is based on a braking command modifier value or a powertrain command modifier value. 12 . The method of claim 11 , wherein the brake command modifier value is a scalar value. 13 . The method of claim 11 , wherein the powertrain command modifier value is a scalar value. The method of claim 11 , wherein the brake command modifier value is a reduced value.

15. The method of claim 11 wherein the powertrain command modifier value is a reduction value.

16. The method of claim 11, wherein the brake command modifier value based on at least one of the measured vehicle speed or the yaw rate error comprises utilizing at least one of: a two-dimensional yaw rate error versus speed table; a one-dimensional yaw rate error table; a single yaw rate error value; a two-dimensional yaw rate error versus wheel speed table; a two-dimensional yaw rate error versus yaw rate table; a three-dimensional table of yaw rate error, yaw rate, wheel speed; or other numerical calculations.

17. The method of claim 11, further comprising: A brake steering command in a pre-expanded state is communicated to a brake steering command modifier prior to providing a modified brake command based on the brake command modifier value.

18. The method of claim 9, wherein the calculated modulation is a scalar value.

Images