Understeer and oversteer feel correction

Abstract

A method for controlling steering wheel torque in a steering system of a vehicle includes obtaining at least one of a reference yaw rate of the vehicle and a reference yaw acceleration of the vehicle; obtaining at least one of a yaw rate error and a yaw acceleration error based on at least one of the reference yaw rate and the reference yaw acceleration; obtaining a steering wheel torque correction based on at least one of the yaw rate error and the yaw acceleration error; adjusting a reference torque using the steering wheel torque correction amount; and controlling the steering wheel torque using a reference torque adjusted using the steering wheel torque correction amount.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 605,166, filed on December 1, 2023. The entire disclosure of the above - cited application is incorporated herein by reference. Technical Field

[0003] This disclosure relates to systems and methods for controlling steering feel and driver feedback in a steering system. Background Art

[0004] Vehicles (such as cars, trucks, sport utility vehicles, crossovers, minivans, ships, aircraft, all - terrain vehicles, recreational vehicles or other suitable forms of transportation) typically include a steering system, such as an electric power steering (EPS) system, a steer - by - wire (SbW) steering system, a hydraulic steering system or other suitable steering systems. The steering system of such a vehicle typically controls various aspects of vehicle steering, including providing steering assistance to the operator of the vehicle, controlling the vehicle's steering wheel, etc. Summary of the Invention

[0005] This disclosure generally relates to systems and methods for controlling steering feel and driver feedback in a steering system.

[0006] One aspect of the disclosed embodiments includes a method for controlling the steering wheel torque in a steering system of a vehicle. The method includes: obtaining at least one of a reference yaw rate and a reference yaw acceleration of the vehicle; obtaining at least one of a yaw rate error and a yaw acceleration error based on at least one of the reference yaw rate and the reference yaw acceleration; obtaining a steering wheel torque correction amount based on at least one of the yaw rate error and the yaw acceleration error; using the steering wheel torque correction amount to adjust a reference torque; and controlling the steering wheel torque using the reference torque adjusted by the steering wheel torque correction amount.

[0007] In another aspect, a system is configured to perform one or more functions of the various methods described herein. In another aspect, a processor is configured to execute instructions stored in a memory to perform one or more functions of the various methods described herein.

[0008] Other applicable fields of the present disclosure will become apparent from the detailed description, claims and drawings. The detailed description and specific examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Brief Description of the Drawings

[0009] The present disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be emphasized that, in accordance with normal practice, the various features of the drawings are not drawn to scale. Instead, the dimensions of the various features are arbitrarily enlarged or reduced for clarity.

[0010] Figure 1A A vehicle generally showing the principles of the present disclosure is shown.

[0011] Figure 1B A controller generally showing the principles of the present disclosure is shown.

[0012] Figure 2A An example rack or RWA controller and a column or steering wheel actuator (HWA) of a steering system generally showing the principles of the present disclosure are shown.

[0013] Figure 2B A functional block diagram of an example steering correction system showing the principles of the present disclosure is shown.

[0014] Figure 3 Is a flowchart generally showing a method for performing steering correction techniques in accordance with the principles of the present disclosure. Detailed Description

[0015] The following discussion pertains to various embodiments of the present disclosure. Although one or more of these embodiments may be preferred, the disclosed embodiments should not be construed or otherwise used to limit the scope of the present disclosure (including the claims). Additionally, those skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only as an illustration of that embodiment and is not intended to imply that the scope of the present disclosure (including the claims) is limited to that embodiment.

[0016] As described, vehicles (such as cars, trucks, sport utility vehicles, crossovers, minivans, ships, aircraft, all-terrain vehicles, recreational vehicles, or other suitable forms of transportation) typically include a steering system, such as an electric power steering (EPS) system, a steer-by-wire (SbW) steering system, a hydraulic steering system, or other suitable steering systems. The steering system of such a vehicle typically controls various aspects of the vehicle's steering, including providing steering assistance to the operator of the vehicle, controlling the vehicle's steering wheel, and the like.

[0017] The SbW steering system may include: at least one steering wheel actuator (HWA), such as a steering wheel, which is used by the driver to laterally control the vehicle; and at least one wheel actuator (RWA), which is used to control the steering axle of the vehicle and generates the lateral movement of the vehicle in response to the movement of the HWA. The SbW system may also include a controller, such as a domain controller, configured to store and execute control logic.

[0018] SbW steering systems and other types of steering systems can be configured to provide steering feedback to the driver, such as torque or other feedback. For example, the forces and moments at the front tire contact surface are transmitted through the tire carcass, wheel, hub, kingpin, tierod and transmitted into the steering rack; the forces and moments are measured / determined by the RWA and associated controller (e.g., ECU), transmitted to the HWA controller, and provided to the driver as steering wheel torque feedback. In a connected system or SbW system, this feedback can provide the driver with tactile information that indicates whether the vehicle has reached the limit of understeer or US (e.g., the condition where the front tires lose traction before the rear tires) or the limit of oversteer or OS (e.g., the condition where the rear tires lose traction before the front tires). Certain vehicle chassis configurations may not be able to generate sufficient torque feedback in the steering wheel to determine the limit condition. The SbW system characteristics may not allow sufficient torque feedback to be generated in the steering wheel to determine the limit condition. The lack of sufficient steering feedback for the limit condition may have an adverse effect on the driver's ability to control the vehicle.

[0019] In one example, the steering system can calculate the yaw rate and yaw acceleration expected by the driver based on the wheel angle and vehicle speed. The yaw rate error and yaw acceleration error can be calculated using the yaw rate and yaw acceleration expected by the driver and the actual vehicle yaw rate and yaw acceleration. The status flag can be set based on the yaw rate error and yaw acceleration error and a calibratable threshold (e.g., based on whether the error reaches / exceeds the respective threshold). The rack force calculation can switch or blend between two different rack force calculation methods based on whether various status flags are set. The calculated rack force can be used as an input for the steering wheel torque calculation. However, in this example, the steering wheel torque may not be directly adjusted, but only indirectly adjusted by adjusting the rack force. In other words, the rack force calculation is only adjusted to a value between different rack force calculation methods (i.e., the adjustment of the rack force and the steering wheel torque is bounded). Therefore, this example steering system can be applied to steering systems that calculate the rack force in the steering system (e.g., in an SbW system), but not to systems where the rack force is physically transmitted to the steering wheel in the steering system (e.g., a traditional EPS system).

[0020] Steering correction (e.g., steering wheel torque control) systems and methods according to the present disclosure are configured to provide or exaggerate haptic feedback to a driver via steering wheel torque to indicate that a vehicle is in a physical state of extreme understeer or oversteer. In this way, sufficient information is provided to the driver for making steering decisions during extreme understeer or extreme oversteer events. In one example, the systems and methods described herein are configured to use yaw rate, yaw rate error, yaw acceleration, and yaw acceleration error to calculate and control the haptic feedback provided to the driver. As an example, a steering wheel torque correction amount or scalar is calculated based on the yaw rate error and the yaw acceleration error and applied to a steering wheel target or reference torque to scale / adjust the reference torque upward (e.g., during an oversteer event) or downward (e.g., during an understeer event). Additionally, a steering wheel torque correction amount may be selectively calculated and applied to damping and return correction (e.g., constant velocity return or CVR) calculations / adjustments.

[0021] Figure 1A A vehicle 10 is generally shown in accordance with the principles of the present disclosure. The vehicle 10 may include any suitable vehicle, such as a sedan, a truck, a sport utility vehicle, a minivan, a crossover vehicle, any other passenger vehicle, any suitable commercial vehicle, or any other suitable vehicle. Although the vehicle 10 is shown as a passenger vehicle having wheels and being for use on a road, the principles of the present disclosure may be applied to other vehicles, such as airplanes, boats, trains, drones, or other suitable vehicles.

[0022] The vehicle 10 includes a vehicle body 12 and a hood 14. A passenger compartment 18 is at least partially defined by the vehicle body 12. Another portion of the vehicle body 12 defines an engine compartment 20. The hood 14 may be movably attached to a portion of the vehicle body 12 such that when the hood 14 is in a first position or an open position, the hood 14 provides access to the engine compartment 20, and when the hood 14 is in a second position or a closed position, the hood 14 covers the engine compartment 20. In some embodiments, the engine compartment 20 may be provided at the rear of the vehicle 10, rather than as generally shown.

[0023] The passenger compartment 18 may be disposed behind the engine compartment 20, but in embodiments where the engine compartment 20 is disposed at the rear of the vehicle 10, the passenger compartment may be disposed in front of the engine compartment 20. The vehicle 10 may include any suitable propulsion system, which may include: an internal combustion engine, one or more electric motors (e.g., for an electric vehicle), one or more fuel cells, a hybrid propulsion system including a combination of an internal combustion engine and one or more electric motors (e.g., for a hybrid vehicle), and / or any other suitable propulsion system.

[0024] In some embodiments, the vehicle 10 may include a petrol or gasoline fuel engine, such as a spark ignition engine. In some embodiments, the vehicle 10 may include a diesel fuel engine, such as a compression ignition engine. The engine compartment 20 houses and / or encloses at least some components of the propulsion system of the vehicle 10. Additionally or alternatively, propulsion controls (such as an accelerator actuator (e.g., an accelerator pedal), a brake actuator (e.g., a brake pedal), a steering wheel, and other such components) are disposed in the passenger compartment 18 of the vehicle 10. The propulsion controls may be actuated or controlled by an operator of the vehicle 10 and may be directly connected to corresponding components of the propulsion system, such as a throttle, brakes, vehicle axles, a vehicle transmission, etc. In some embodiments, the propulsion controls may transmit signals to a vehicle computer (e.g., via drive-by-wire), which may in turn control corresponding propulsion components of the propulsion system. Thus, in some embodiments, the vehicle 10 may be an autonomous vehicle.

[0025] In some embodiments, the vehicle 10 includes a transmission that communicates with a crankshaft via a flywheel or a clutch or a fluid coupling. In some embodiments, the transmission includes a manual transmission. In some embodiments, the transmission includes an automatic transmission. In the case of an internal combustion engine or a hybrid vehicle, the vehicle 10 may include one or more pistons that operate in concert with the crankshaft to generate a force that is transmitted through the transmission to one or more axles that drive the wheels 22 to rotate. When the vehicle 10 includes one or more electric motors, a vehicle battery and / or a fuel cell supplies energy to these electric motors to cause the wheels 22 to rotate.

[0026] Vehicle 10 may include an automatic vehicle propulsion system, such as cruise control, adaptive cruise control, automatic braking control, other automatic vehicle propulsion systems, or combinations thereof. Vehicle 10 can be an autonomous or semi-autonomous vehicle, or other suitable type of vehicle. Vehicle 10 may include more or fewer features than those generally shown and / or disclosed herein.

[0027] In some embodiments, vehicle 10 may include an Ethernet component 24, a controller area network (CAN) bus 26, a media-oriented system transport component (MOST) 28, a FlexRay component 30 (e.g., a brake-by-wire system, etc.), and a local interconnect network component (LIN) 32. Vehicle 10 may use the CAN bus 26, MOST 28, FlexRay component 30, LIN 32, other suitable networks or communication systems, or combinations thereof to transfer various information from sensors, for example, inside or outside the vehicle, to various processors or controllers, for example, inside or outside the vehicle. Vehicle 10 may include more or fewer features than those generally shown and / or disclosed herein.

[0028] In some embodiments, vehicle 10 may include a steering system, such as an EPS system, a steer-by-wire steering system (e.g., which may include one or more controllers or communicate with the one or more controllers that control components of the steering system without using a mechanical connection between the steering wheel of vehicle 10 and the wheel 22), a hydraulic steering system (e.g., which may include a magnetic actuator incorporated into a valve assembly of the hydraulic steering system), or other suitable steering systems.

[0029] The steering system may include an open-loop feedback control system or mechanism, a closed-loop feedback control system or mechanism, or combinations thereof. The steering system can be configured to receive various inputs, including but not limited to steering wheel position, input torque, one or more road wheel positions, other suitable inputs or information, or combinations thereof.

[0030] Additionally or alternatively, the inputs may include steering wheel torque, steering wheel angle, motor speed, vehicle speed, estimated electric motor torque command, other suitable inputs, or combinations thereof. The steering system can be configured to provide a steering function and / or control to vehicle 10. For example, the steering system can generate an assist torque based on various inputs. The steering system can be configured to use the assist torque to selectively control a motor of the steering system to provide steering assistance to an operator of vehicle 10.

[0031] In some embodiments, vehicle 10 includes one or more controllers, such as Figure 1BController 100 generally shown therein. Controller 100 may correspond to a steering system controller. Controller 100 may include any suitable controller, such as an electronic control unit or other suitable controller. Controller 100 may be configured to control various functions of, for example, the steering system and / or various functions of vehicle 10. Controller 100 may include a processor 102 and a memory 104. Processor 102 may include any suitable processor, such as those described herein. Additionally or alternatively, in addition to or different from processor 102, controller 100 may include any suitable number of processors. Memory 104 may include a single disk or multiple disks (e.g., a hard disk drive), and includes a storage management module that manages one or more partitions within memory 104. In some embodiments, memory 104 may include flash memory, semiconductor (solid state) memory, etc. Memory 104 may include random access memory (RAM), read only memory (ROM), or a combination thereof. Memory 104 may include instructions that, when executed by processor 102, cause processor 102 to at least control various aspects of vehicle 10. Additionally or alternatively, memory 104 may include instructions that, when executed by processor 102, cause processor 102 to perform functions associated with the systems and methods described herein.

[0032] Controller 100 may receive one or more signals from various measurement devices or sensors 106 that indicate sensed or measured characteristics of vehicle 10. Sensors 106 may include any suitable sensors, measurement devices, and / or other suitable mechanisms. For example, sensors 106 may include one or more torque sensors or devices, one or more steering wheel position sensors or devices, one or more motor position sensors or devices, one or more position sensors or devices, other suitable sensors or devices, or combinations thereof. The one or more signals may indicate steering wheel torque, steering wheel angle, motor speed, vehicle speed, other suitable information, or combinations thereof.

[0033] As used herein, "controller" may refer to a hardware module or component including one or more processors or microcontrollers, memory, sensors, one or more actuators, communication interfaces, etc., and any part thereof may be collectively referred to as "circuitry". As described herein, the corresponding functions and steps performed by a given controller, control circuitry, etc. may be performed jointly by multiple controllers, processors, etc. For example, a processor, processing device, controller, control circuitry, etc. "configured to perform" may refer to a single processor, processing device, controller, etc. configured to perform both A and B, or may refer to a first processor, processing device, controller, etc. configured to perform A and a second processor, processing device, controller, etc. configured to perform B. For simplicity, "control circuitry configured to perform A and B" may refer to a single or multiple processors, processing devices, controllers, etc. jointly configured to perform A and B.

[0034] In some embodiments, controller 100 may perform the methods described herein. However, the methods described herein as performed by controller 100 are not meant to be limiting, and any type of software executed on a controller, processor, or other circuitry may implement the hysteresis adjustment techniques described herein without departing from the scope of the present disclosure. For example, a controller such as a processor executing software within a computing device may implement the systems and methods described herein.

[0035] Figure 2A An example steering system 200 is shown in accordance with the present disclosure including a rack or RWA controller 202 and a column or hand wheel actuator (HWA) controller 204 of a steering system configured to implement steering correction techniques. For example, HWA controller 204 is configured to generate a hand wheel actuator (HWA) motor torque command based on an estimated rack force (e.g., an estimated rack force signal) received from RWA controller 202 and one or more other input signals (e.g., vehicle speed, hand wheel position, and hand wheel speed). RWA controller 202 is configured to determine the estimated rack force based on the motor torque required to achieve or maintain an actual rack position. Controller 202 and controller 204 may correspond to one or more steering system controllers, be implemented by one or more steering system controllers, etc.

[0036] As an example, HWA controller 204 includes a reference torque calculator 208 configured to calculate a reference torque (T ref)。For example, the reference torque corresponds to the sum of various input / measurement results such as effort, hysteresis, return calibration or CVR, damping, catch, etc. The closed-loop (e.g., PID closed-loop) torque controller 212 is configured to generate and output a motor torque command based at least in part on the force or torque applied by the driver (e.g., "Tbar torque") and the reference torque. The motor torque command is provided as a control signal to control the motor of the steering wheel actuator.

[0037] The estimated rack force corresponds to the measured or estimated wheel actuator motor torque. Thus, the estimated rack force (and any estimated rack force offset or error) is a key factor for determining the force provided by the motor of the steering wheel actuator.

[0038] In some examples, the HWA controller 204 may further include a C-factor lookup module 216 and a rack position reference calculator 220. For example, the rack position reference calculator 220 is configured to generate a rack position reference based on the C-factor received from the C-factor lookup module 216. The C-factor can be determined based on the steering wheel angle ("HwAg") corresponding to the driver input (e.g., the steering wheel angle indicating the driver's intention communicated via the steering wheel). Example systems and methods for obtaining the rack position reference and the C-factor are described in more detail in U.S. Patent Application No. 18 / 318,657, filed on May 16, 2023, the entire content of which is incorporated herein by reference.

[0039] The RWA controller 202 includes a rack position controller 224 (e.g., a PID rack position controller) that is configured to generate one or more rack position control signals based on the actual rack position and the rack position reference (e.g., based on the difference between the actual rack position and the rack position reference). For example, the rack position control signals may include, but are not limited to, rack motor speed and motor torque command (e.g., a signal indicating the amount of torque applied by the driver) signals. In this way, the rack position is controlled to follow the driver's intention (as indicated by the rack reference position).

[0040] The rack force predictor 226 generates an estimated rack force based on the output of the rack position controller 224 (e.g., based on a function of the rack motor speed, rack motor torque command, etc.). In various examples, the estimated rack force can be calculated based on the amount of torque applied by the driver to the steering wheel (as indicated by the rack motor torque command, various sensor signals, etc.). As shown, the rack force predictor 226 can output the estimated rack force, and the reference torque calculator 208 (and / or another component of the HWA controller 204, RWA controller 202, etc.) can obtain an estimated rack load based on the estimated rack force. In other examples, the rack force predictor 226 can output an estimated rack load. In some cases, the terms "estimated rack force" and "estimated rack load" can be used interchangeably.

[0041] For example, for RWA position control, the rack position reference signal ("RackPosRef") can be calculated based on the position error ("PosErr") between the ADAS rack position reference value or signal ("ADASRackPosRef") and the HWA rack position reference value or signal ("HWARackPosRef"). Conversely, HWA position control is based on the position error between the HWA position and the RWA position, such that the steering wheel can be controlled to rotate in a manner consistent with the rotation of the wheels in the hands-off state.

[0042] The reference torque can correspond to the desired torque, ideal torque, or target torque that the driver (i.e., at the steering wheel) would feel. As described above, the reference torque is calculated based on inputs including but not limited to driver input (e.g., the input torque corresponding to the steering angle of the steering wheel), road conditions, damping, hysteresis, etc. The torque at the steering wheel is controlled (e.g., via HWA) to match the reference torque. For example, the output of one or more sensors that measure the actual torque at the wheels is used to minimize the difference between the reference torque and the actual torque.

[0043] The effort function (e.g., the effort function implemented by the reference torque calculator 208) defines the relationship between the driver input (e.g., the force or torque applied by the driver to the steering wheel, which can be referred to as the "effort") and the response of the steering system (i.e., the movement). For example, the effort function can output an effort value based on a look-up table or other function (e.g., by using the estimated rack load as an input). The estimated rack load can be modified by adding the calculated return load value to the estimated rack load before being input into the look-up table. The effort function indicates the amount of effort that the driver needs to apply to cause the desired response.

[0044] The steering system 200 according to the present disclosure is configured to implement steering correction (e.g., understeer / oversteer correction) techniques, as described in more detail below. For example, the steering system 200 may include a linear bicycle model that is optimized for yaw rate prediction to generate at least one of an expected / reference yaw rate and a yaw acceleration based on vehicle speed and wheel angle. The expected / reference yaw rate and yaw acceleration provide an indication of the presence of understeer or oversteer. The linear bicycle model is one example model that can be used to represent the expected behavior of the vehicle as perceived by the driver, but other types of models may also be used. The understeer / oversteer detection module or circuit compares at least one of the actual yaw rate and yaw acceleration of the vehicle with at least one of the reference yaw rate and acceleration generated by the linear bicycle model, and calculates a yaw rate error and a yaw acceleration error accordingly (i.e., based on the difference between the expected / reference yaw rate and acceleration and the actual yaw rate and acceleration). The steering wheel torque correction amount calculation module or circuit receives the yaw rate and yaw acceleration errors and calculates a correction amount (e.g., a steering wheel torque correction amount) to be applied to the steering wheel torque (e.g., further depending on the physical events or states of the vehicle).

[0045] Figure 2B Another example of the steering system 200 described above is shown in Figure 2A The steering system 200 includes various components configured to implement steering correction techniques in accordance with the principles of the present disclosure. For simplicity, Figure 2A Some of the components of the steering system 200 shown in Figure 2B are omitted from Figure 2A However, the various components of the steering system 200 shown in Figure 2B may be configured to implement the

[0046] functions / components of Figure 2BAs shown, the RWA controller 202 is configured to determine at least one of a yaw rate error and a yaw acceleration error and provide it to the HWA controller 204. The yaw rate error and the acceleration error indicate the difference between a reference yaw rate and acceleration value (e.g., an indicator of the expected yaw rate / acceleration) and an actual (e.g., measured or calculated) yaw rate and acceleration value, and this difference indicates the amount of understeer or oversteer. The HWA controller 204 includes a steering wheel (HW) torque correction calculation module 230, which is configured to calculate one or more HW torque corrections (e.g., a scaling factor) based on the yaw rate error and the acceleration error. The HW torque corrections are provided to the reference torque calculator 208. Although shown as separate from the reference torque calculator 208, the functions associated with the HW torque correction calculation module 230 may be implemented within the reference torque calculator 208 and / or another component, within the RWA controller 202, etc. For example, in some examples, the yaw rate error and the acceleration error may be provided directly to the reference torque calculator 208, which may be configured accordingly to calculate the HW torque corrections.

[0047] For example, the reference torque calculator 208 is configured to calculate a reference torque based on various inputs, including the output of the force function as described above (and shown at 232). Other measurements or inputs include, but are not limited to, the damping function or calculation 234 and the output of the return correction / CVR function or calculation 236. The reference torque calculator 208 according to the present disclosure is also configured to apply an HW torque correction (e.g., a scaling factor) to the calculated reference torque value to scale the reference torque up or down. In this way, the reference torque can be scaled up or down in understeer and oversteer situations to correct the driver's feel and HW response during these situations. For example, when the detected understeer (i.e., based on the yaw rate / acceleration error) increases, the HW torque correction can adjust the reference torque downward. Conversely, when the detected oversteer increases, the HW torque correction can adjust the reference torque upward.

[0048] In this way, the reference torque controller 208 according to the present disclosure is configured to generate and adjust the reference torque in understeer and oversteer situations (e.g., based on the yaw rate error and the yaw acceleration error) by obtaining and applying one or more HW torque corrections (scaling factors).

[0049] In one example, system 200 (e.g., RWA controller 202) includes a linear bicycle model or other model 238 configured to generate an expected / reference yaw rate and an expected / reference yaw acceleration based on vehicle speed and wheel angle. The expected / reference yaw rate and acceleration may correspond to the yaw rate and acceleration expected by the driver. The expected / reference yaw rate and yaw acceleration provide an indication of understeer or oversteer. As an example, the linear bicycle model 238 receives vehicle speed and an input indicative of the wheel angle, such as a corrected wheel angle. A steering offset correction (SOC) module (e.g., circuitry, model, measurement, calculation, or function, etc.) 240 may calculate a corrected wheel angle based on wheel angle measurements, values, or signals (e.g., a wheel angle value obtained using a wheel (RW) angle calculation module 242 configured to obtain the wheel angle based on the rack position).

[0050] The reference yaw rate and reference yaw acceleration are provided to an understeer / oversteer (US / OS) detection module 248 configured to calculate a yaw rate error and a yaw acceleration error based on (i) the reference yaw rate and reference yaw acceleration and (ii) the actual (e.g., measured, estimated, calculated, etc.) yaw rate and yaw acceleration. For example, the yaw rate error corresponds to the difference between the reference yaw rate and the actual yaw rate, and the yaw acceleration error corresponds to the difference between the reference yaw acceleration and the actual yaw acceleration. The yaw rate acceleration may be calculated based on multiple samples of the yaw rate. As an example, the US / OS detection module 248 receives a corrected yaw rate indicative of the actual yaw rate from a yaw rate offset correction (YOC) module 252 configured to calculate the corrected yaw rate based on yaw rate measurements, signals, or values.

[0051] In one example implementation, the linear bicycle model 238 is configured to obtain a reference yaw rate r LBM (where “LBM” corresponds to “linear bicycle model”) and a reference yaw acceleration The US / OS detection module 248 calculates a vehicle rotation error (e.g., yaw rate error r err and yaw acceleration error ) according to the following equation:[[]]

[0052] r err = sgn(r LBM ) * (r LBM - r act ); and

[0053]

[0054] where sgn is the sign function, r act is the actual yaw rate, and is the actual yaw acceleration.

[0055] Based on the yaw rate error r err and the yaw acceleration error Limit understeer or oversteer events can be defined in different value ranges as follows:

[0056] Steady-state limit understeer condition;

[0057] Steady-state limit oversteer condition;

[0058] Transient, increasing limit understeer condition;

[0059] Transient, increasing limit oversteer condition;

[0060] Transient, decreasing limit understeer condition; and

[0061] Transient, decreasing limit oversteer condition.

[0062] The yaw rate error r err and the yaw acceleration error are used to scale (e.g., using the HW torque correction / scaling factor) the force feedback provided to the driver via the force function, as described above. The base force value obtained using the force function output and used for steering wheel (reference) torque calculation can correspond to T ref,RFeffort . According to the principles of the present disclosure, the corrected base force can be calculated according to the following formula:

[0063]

[0064] where is the calibratable scaling factor for US / OS (i.e., corresponding to the HW torque correction), as a function of the yaw rate error, the yaw acceleration error, and the longitudinal speed v. Applying the HW torque correction directly adjusts the steering wheel torque feedback target (as represented by the reference torque provided to the torque controller 212) by scaling it up or down. As an example, in an SbW system, during limit understeer and limit oversteer conditions, the HW torque correction or scalar can be applied according to the following conditions:

[0065] For sgn(r LBM) = sgn(r act ), r err > 0: Extreme understeer, and

[0066] For sgn(r LBM ) = sgn(r act ), r err < 0: Extreme oversteer,

[0067] In this way, the steering wheel torque feedback is reduced during an understeer event to amplify the effect of understeer on the driver. The corresponding reduction in the steering force is consistent with the physics-based behavior in the connected (i.e., non-SbW) system. Conversely, the steering wheel torque feedback is increased during an oversteer event to amplify the effect of oversteer on the driver. During the initial stage of oversteer, the corresponding increase in the steering force is consistent with the physics-based behavior in the connected system. Additionally, the technique considers whether the rotation of the vehicle and the rotation of the vehicle expected by the driver are in the same direction (e.g., based on the output of the linear bicycle model 238) and considers the sign of r err .

[0068] In some examples, the steering correction technique of the present disclosure can be implemented in an EPS system. In these examples, the HW torque correction amount can be applied as an "auxiliary" scalar. For example, the HW torque correction amount in these examples can correspond to the inverse (inversion) or inverted value of the HW torque correction amount described above for the SbW system. In other words, for extreme understeer situations, an auxiliary scalar greater than 1 can be used to increase the assist (i.e., increase the reference torque) and reduce the steering force. Conversely, for extreme oversteer situations, an auxiliary scalar less than 1 and greater than 0 can be used to reduce the assist and increase the steering force.

[0069] In another example, the correction amount / scaling factor K can vary based on r err and as follows:

[0070] Steady-state extreme understeer condition;

[0071] Steady-state extreme oversteer condition;

[0072] Transient, increasing extreme understeer condition;

[0073] Transient, increasing extreme oversteer condition;

[0074] Transient, decreasing limit understeer condition; and

[0075] Transient, decreasing limit oversteer condition;

[0076] In addition, instead of using yaw acceleration error to determine the correction amount or in addition to using yaw acceleration error to determine the correction amount, steering wheel torque, steering wheel speed, and / or other inputs can be used to determine the HW torque correction amount / scaling factor.

[0077] Although the above describes these techniques with respect to the force T based on the rack force ref,RFeffort these techniques of the present disclosure can be applied to other steering wheel torques, such as damping force and / or CVR function / value, in other examples.

[0078] For example, during understeer and oversteer conditions, CVR torque may cause inaccurate / undesired torque feedback, which may interfere with the driver's perception of steering. Therefore, during understeer and oversteer conditions, the HW torque correction amount can be used to scale down / reduce the CVR torque command applied to the reference torque.

[0079] In some examples, the CVR torque can be tuned to add damping to the system 200. During understeer and oversteer events, turning off the CVR may result in insufficient steering damping, which may interfere with the driver's perception and steering. Therefore, during understeer and oversteer conditions, the HW torque correction amount can be used to scale up / increase the damping torque command applied to the reference torque.

[0080] In some examples, the damping can be actively tuned such that the damping effect masks the torque feedback during understeer and oversteer conditions, which may interfere with the driver's perception and steering. Therefore, during understeer and oversteer conditions, the HW torque correction amount can be used to scale down / reduce the damping torque command applied to the reference torque.

[0081] Thus, as an example, the damping or damping force function 234 and the CVR function 236 may receive the yaw rate error and the yaw rate acceleration and / or the respective HW torque corrections as inputs. In this way, the damping force and the CVR torque value used to adjust the reference torque can be further corrected based on the yaw rate error and the yaw rate acceleration in a manner similar to the correction of the reference torque described above. As an example, the US / OS detection module 248 is configured to calculate a reverse steering flag, value, or other indicator (e.g., using a steering wheel sensor, reference and actual yaw values, etc.) indicating whether the driver has detected / is performing a reverse steering. For example, the reverse steering flag can be calculated by comparing the sign of the actual yaw rate (e.g., a positive or negative sign indicating the direction of the actual yaw) with the sign of the reference yaw rate (e.g., a positive or negative sign indicating the direction of the intended yaw). In other words, if the actual yaw rate and the reference / expected yaw rate have the same sign, the driver is not performing a reverse steering maneuver. Conversely, if the actual yaw rate and the reference / expected yaw rate have different (e.g., opposite) signs, the driver is performing a reverse steering maneuver. Thus, the reverse steering flag can be set, have a value of 1, etc. in response to determining that reverse steering has been detected, and can not be set, have a value of 0, etc. in response to determining that reverse steering has not been detected.

[0082] For example, the system 200 is configured to detect whether a reverse steering exists (i.e., whether the driver is performing a reverse steering maneuver where the steering wheel is rotating in a position opposite to the yaw of the vehicle), and if a reverse steering exists, selectively calculate the HW torque correction / scaling value and apply it to the CVR or damping torque value. As an example, the HW torque correction calculation module 230 receives the reverse steering flag and further adjusts one or more HW torque corrections based on the reverse steering flag.

[0083] Figure 3 is a flowchart generally showing a method 300 for performing steering correction techniques in accordance with the principles of the present disclosure. For example, one or more computing devices, processors, or processing devices, etc. are configured to execute instructions to implement the method 300, such as one or more processors in the processor of the system described herein (e.g., the computing device or processor of a vehicle configured to implement the controller 100, system 200, etc.). In some examples, one or more steps of the method 300 described below may be skipped or omitted, and / or one or more of these steps may be executed in an order different from the described order.

[0084] At 304, method 300 includes calculating or otherwise obtaining an indicator of the rotational / yaw that the driver anticipates (e.g., at least one of a reference yaw rate and a reference yaw acceleration). For example, obtaining the reference yaw rate and / or the reference yaw acceleration may include using a linear bicycle model to calculate the reference yaw rate and the reference yaw acceleration.

[0085] At 308, method 300 includes determining whether the vehicle is in an understeer condition or an oversteer condition. For example, determining whether the vehicle is in an understeer condition or an oversteer condition may include calculating a yaw rate error and / or a yaw acceleration error based on the difference between the reference yaw rate and the reference yaw acceleration and / or the difference between the actual yaw rate and the actual yaw acceleration, respectively, where a non-zero error value indicates understeer or oversteer. In some examples, method 300 further includes calculating / determining a counter-steer flag at 308 that indicates whether the driver is performing a counter-steering maneuver, as described herein.

[0086] At 312, method 300 includes calculating one or more HW torque corrections based at least in part on the yaw rate error and / or the yaw acceleration error. For example, the HW torque correction may correspond to a decrease in the reference torque value for an understeer condition (e.g., a multiplier less than 1.0) and an increase in the reference torque value for an oversteer condition (e.g., a multiplier greater than 1.0). In some examples, method 300 further includes calculating one or more HW torque corrections at 312 based on the counter-steer flag, as described herein.

[0087] At 316, method 312 includes generating a reference torque (e.g., a HW torque target) using the HW torque correction. For example, generating the reference torque may include obtaining (e.g., using a force function) a base force value / torque and applying the HW torque correction to the base force value. In other words, generating the reference torque may include adjusting the reference torque up or down using the HW torque correction.

[0088] At 320, method 320 includes controlling the steering wheel torque based on the reference torque. For example, controlling the steering wheel torque may include providing the reference torque to a torque controller and using the torque controller to control the HWA.

[0089] The foregoing discussion is intended to illustrate the principles of the invention and various embodiments. Once the above disclosure is fully understood, many variations and modifications will become obvious to those skilled in the art. The appended claims are intended to be construed to cover all such variations and modifications.

[0090] As used herein, the term "example" is used to mean an example, instance, or illustration. Any aspect or design described herein as an "example" is not necessarily to be construed as preferred or advantageous over other aspects or designs. Instead, the use of the term "example" is intended to present concepts in a concrete fashion. As used in this application, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless otherwise specified or clear from the context, "X includes A or B" is intended to mean any of the natural inclusive permutations. That is, if X includes A, X includes B, or X includes both A and B, then "X includes A or B" is satisfied under any of the foregoing instances. Additionally, as used in this application and the appended claims, the articles "a" and "an" shall generally be construed to mean "one or more" unless otherwise specified or clear from the context that it is meant in the singular form. Further, the use of the term "one embodiment" or "an embodiment" throughout this document is not necessarily intended to refer to the same embodiment or implementation unless so described specifically.

[0091] Embodiments of the systems, algorithms, methods, instructions, etc. described herein may be implemented in hardware, software, or any combination thereof. Hardware may include, for example, a computer, an intellectual property (IP) core, an application specific integrated circuit (ASIC), a programmable logic array, an optical processor, a programmable logic controller, microcode, a microcontroller, a server, a microprocessor, a digital signal processor, or any other suitable circuitry. In the claims, the term "processor" shall be understood to cover any of the foregoing hardware individually or in combination. The terms "signal" and "data" may be used interchangeably.

[0092] As used herein, the term "module" may include: a packaged functional hardware unit designed to be used with other components, a set of instructions executable by a controller (e.g., a processor executing software or firmware), a processing circuit configured to perform a specific function, and an independent hardware or software component interfacing with a larger system. For example, a module may include: an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), circuitry, digital logic circuitry, analog circuitry, a combination of discrete circuits, gates, and other types of hardware, or combinations thereof. In other embodiments, a module may include a memory storing instructions that may be executed by a controller to implement the features of the module.

[0093] In addition, in one aspect, for example, a general-purpose computer or a general-purpose processor having a computer program can be used to implement the systems described herein, and the computer program, when executed, implements any one of the various methods, algorithms, and / or instructions described herein. Additionally or alternatively, for example, a special-purpose computer / processor can be utilized, which can include additional hardware for implementing any one of the methods, algorithms, or instructions described herein.

[0094] Furthermore, all or a portion of an embodiment of the present disclosure can take the form of a computer program product accessible from, for example, a computer-usable medium or a computer-readable medium. A computer-usable medium or a computer-readable medium can be any device that can tangibly contain, store, communicate, or transport a program for use by or in connection with any processor. The medium can be, for example, an electronic, magnetic, optical, electromagnetic, or semiconductor device. Other suitable media are also available.

[0095] The foregoing embodiments, implementations, and aspects have been described to enable an easy understanding of the present invention and do not limit the present invention. On the contrary, the present invention is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, and the scope thereof should be accorded the broadest interpretation so as to cover all such modifications and equivalent structures permitted under the law.

Claims

1. A method for controlling a steering wheel torque in a steering system of a vehicle, the method comprising: obtaining at least one of a reference yaw rate of the vehicle and a reference yaw acceleration of the vehicle; obtaining at least one of a yaw rate error and a yaw acceleration error based on at least one of the reference yaw rate and the reference yaw acceleration; obtaining a steering wheel torque correction based on at least one of the yaw rate error and the yaw acceleration error; Using the steering wheel torque correction amount, adjusting the reference torque; as well as The steering wheel torque is controlled using the reference torque adjusted using the steering wheel torque correction amount.

2. The method according to claim 1, further comprising: At least one of the reference yaw rate and the reference yaw acceleration is obtained based on a wheel angle.

3. The method according to claim 1, further comprising: At least one of the reference yaw rate and the reference yaw acceleration is obtained using at least one of a vehicle model and a driver intention model.

4. The method according to claim 1, further comprising: At least one of the yaw rate error and the yaw acceleration error is obtained based on at least one of the reference yaw rate and the reference yaw acceleration and at least one of an actual yaw rate and an actual yaw acceleration.

5. The method according to claim 1, wherein: At least one of the yaw rate error and the yaw acceleration error indicates at least one of an understeer condition and an oversteer condition of the vehicle.

6. The method according to claim 5, wherein: The steering wheel torque correction is configured to reduce the reference torque when at least one of the yaw rate error and the yaw acceleration error indicates the understeer condition.

7. The method according to claim 5, wherein: The steering wheel torque correction is configured to increase the reference torque when at least one of the yaw rate error and the yaw acceleration error indicates the oversteer condition.

8. The method according to claim 1, wherein: Adjusting the reference torque using the steering wheel torque correction includes applying the steering wheel torque correction to an output of a force function.

9. The method according to claim 1, further comprising: At least one of a damping torque and a return correction torque is adjusted based on at least one of the yaw rate error and the yaw acceleration error.

10. The method according to claim 9, further comprising: Determine if a reverse steering condition exists; And, further based on whether the reverse steering condition exists, the steering wheel torque correction amount is obtained.

11. A system for controlling steering wheel torque in a steering system of a vehicle, the system comprising: A processor configured to execute instructions stored in a memory, wherein executing the instructions enables the processor to: obtaining at least one of a reference yaw rate of the vehicle and a reference yaw acceleration of the vehicle, obtaining at least one of a yaw rate error and a yaw acceleration error based on at least one of the reference yaw rate and the reference yaw acceleration, obtaining a steering wheel torque correction amount based on at least one of the yaw rate error and the yaw acceleration error, Using the steering wheel torque correction amount, adjusting the reference torque, and The steering wheel torque is controlled using the reference torque adjusted using the steering wheel torque correction amount.

12. The system according to claim 11, wherein: The processor is configured to obtain at least one of the reference yaw rate and the reference yaw acceleration based on a wheel angle.

13. The system according to claim 11, wherein: The processor is configured to obtain at least one of the reference yaw rate and the reference yaw acceleration using at least one of a vehicle model and a driver intention model.

14. The system according to claim 11, wherein: The processor is configured to obtain at least one of the yaw rate error and the yaw acceleration error based on at least one of the reference yaw rate and the reference yaw acceleration and at least one of an actual yaw rate and an actual yaw acceleration.

15. The system according to claim 11, wherein: At least one of the yaw rate error and the yaw acceleration error indicates at least one of an understeer condition and an oversteer condition of the vehicle.

16. The system of claim 15, wherein: The steering wheel torque correction is configured to reduce the reference torque when at least one of the yaw rate error and the yaw acceleration error indicates the understeer condition.

17. The system of claim 15, wherein: The steering wheel torque correction is configured to increase the reference torque when at least one of the yaw rate error and the yaw acceleration error indicates the oversteer condition.

18. The system of claim 11, wherein: Adjusting the reference torque using the steering wheel torque correction includes applying the steering wheel torque correction to an output of a force function.

19. The system of claim 11, wherein: The processor is configured to adjust at least one of a damping torque and a return correction torque based on at least one of the yaw rate error and the yaw acceleration error.

20. A system for controlling a steering wheel torque of a steering system of a vehicle, the system comprising: a wheel actuator controller configured to: (i) obtain at least one of a reference yaw rate of the vehicle and a reference yaw acceleration of the vehicle, and (ii) obtain at least one of a yaw rate error and a yaw acceleration error based on at least one of the reference yaw rate and the reference yaw acceleration; and a steering wheel actuator controller configured to: (i) obtain a steering wheel torque correction amount based on at least one of the yaw rate error and the yaw acceleration error, (ii) adjust a reference torque using the steering wheel torque correction amount, and (iii) control the steering wheel torque using the reference torque adjusted using the steering wheel torque correction amount, wherein the steering wheel actuator controller is configured to use the steering wheel torque correction to: (i) reduce the reference torque in response to determining that at least one of the yaw rate error and the yaw acceleration error indicates that the vehicle is in an understeer condition, and (ii) increase the reference torque in response to determining that at least one of the yaw rate error and the yaw acceleration error indicates that the vehicle is in an oversteer condition.

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