Steer-by-wire steering wheel dynamic misalignment target correction

Abstract

A method for controlling a wheel position in a steer-by-wire (SbW) steering system of a vehicle, comprising using one or more processors to: receive a rack position error indicative of a difference between an actual rack position and a rack position reference; generate an alignment offset based on the rack position error; generate an adjusted wheel position target based on the alignment offset; and control a wheel actuator based on the adjusted wheel position target.

Description

Technical Field

[0001] This disclosure relates to systems and methods for controlling steering wheel and wheel actuators in a steering system. Background Technology

[0002] Vehicles (such as cars, trucks, sport utility vehicles, crossovers, minivans, boats, 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) system, a hydraulic steering system, or other suitable steering system. The steering system of such vehicles typically controls various aspects of the vehicle's steering, including providing steering assistance to the operator and controlling the steerable wheels. Summary of the Invention

[0003] This disclosure relates in its entirety to systems and methods for controlling steering wheel and wheel actuators in a steering system.

[0004] One aspect of the disclosed embodiments includes a method for controlling wheel positions in a steer-by-wire (SbW) steering system of a vehicle. The method includes using one or more processors: receiving a rack position error indicating a difference between an actual rack position and a rack position reference; generating an alignment offset based on the rack position error; generating an adjusted wheel position target based on the alignment offset; and controlling wheel actuators based on the adjusted wheel position target.

[0005] These and other aspects of this disclosure are disclosed in the following detailed description of embodiments, the appended claims and the accompanying drawings. Attached Figure Description

[0006] This disclosure is best understood in conjunction with the accompanying drawings and the following detailed description. It should be emphasized that, in accordance with conventional practice, the various features in the drawings are not drawn to scale. Instead, for clarity, the dimensions of the various features have been arbitrarily enlarged or reduced.

[0007] Figure 1A A vehicle based on the principles of this disclosure is shown in general.

[0008] Figure 1B A controller based on the principles of this disclosure is shown in general.

[0009] Figure 2A An example rack or wheel actuator (RWA) controller and column or steering wheel actuator (HWA) of a steering system according to the principles of this disclosure are generally shown.

[0010] Figure 2BThis is a functional block diagram illustrating an example implementation of the functions and / or components of a steering system and method according to the principles of this disclosure.

[0011] Figure 3 This is a flowchart that generally illustrates a method for performing wheel position control technology according to the principles of this disclosure. Detailed Implementation

[0012] The following discussion pertains to various embodiments of this disclosure. While one or more of these embodiments may be preferred, the disclosed embodiments should not be construed as or otherwise intended to limit the scope of this disclosure (including the claims). Furthermore, those skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is merely illustrative and not intended to imply that the scope of this disclosure (including the claims) is limited to that embodiment.

[0013] As described, vehicles (such as cars, trucks, sport utility vehicles, crossovers, minivans, ships, aircraft, all-terrain vehicles, recreational vehicles, or other suitable forms of transport) typically include a steering system (such as an electric power steering (EPS) system, a steer-by-wire (SbW) system, a hydraulic steering system, or other suitable steering system). 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 steerable wheels of the vehicle, etc.). Although this description pertains to vehicles, the principles of this disclosure can also be implemented in other types of transport or non-transport devices that include a steering system.

[0014] An SbW steering system may include: at least one steering wheel actuator (HWA), such as a steering wheel, used by a driver to laterally control the vehicle; and at least one wheel actuator (RWA) for controlling the steering axis of the vehicle and generating lateral movement of the vehicle in response to movement of the HWA. The SbW system may also include one or more controllers, such as domain controllers, configured to store and execute control logic.

[0015] In an SbW system, the HWA (Hard Wheel Waving) can be configured to detect driver input (e.g., steering wheel input), provide steering force (e.g., torque) feedback to the driver, and generate a RWA (Road Waving) target (e.g., commanding a target rack position) to achieve the driver's desired lateral movement. Conversely, the RWA is configured to execute rack position control (e.g., actuate the rack) to meet the RWA position target and provide road and position feedback (e.g., rack force) to the HWA. In some cases, the wheel position may be misaligned with the steering wheel position (and / or the RWA target), which can be referred to as misalignment between the HWA and RWA. For example, if the RWA is slower / lagging relative to the HWA (and / or the RWA target), the rack may continue to move toward the position target even after the steering wheel has stopped moving, which can lead to undesirable rack movement from the driver's perspective.

[0016] The steering systems and methods according to this disclosure are configured to achieve RWA position target techniques to generate improved (e.g., adjusted or modified) RWA target rack or wheel positions that minimize position errors or misalignments between HWA and RWA. These systems and methods provide an RWA target that ensures the wheels move in the same direction as the steering wheel speed. Furthermore, the RWA target generated using the techniques of this disclosure: (i) stops wheel movement when the steering wheel stops moving; (ii) moves the wheels in a controlled and predictable manner such that excessive or insufficient movement is minimized or does not occur; and (iii) reduces position errors (e.g., reduces position errors over time). As used herein, instances of "wheel" can refer to wheel and / or rack positions, errors, etc.

[0017] Figure 1A A vehicle 10 based on the principles of this disclosure is generally shown. Vehicle 10 may include any suitable vehicle, such as a car, truck, SUV, minivan, crossover, any other passenger vehicle, any suitable commercial vehicle, or any other suitable vehicle. Although vehicle 10 is shown as a wheeled passenger vehicle intended for use on a road, the principles of this disclosure can be applied to other vehicles, such as airplanes, ships, trains, drones, or other suitable vehicles.

[0018] Vehicle 10 includes a vehicle body (fuselage) 12 and an engine 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 engine hood 14 is movably attached to a portion of the vehicle body 12 such that when the engine hood 14 is in a first position or open position, the engine hood 14 provides access to the engine compartment 20, and when the engine hood 14 is in a second position or closed position, the engine hood 14 covers the engine compartment 20. In some embodiments, the engine compartment 20 may be located at the rear of the vehicle 10, rather than as generally shown.

[0019] The passenger compartment 18 may be located behind the engine compartment 20, but in embodiments where the engine compartment 20 is located at the rear of the vehicle 10, the passenger compartment may be located in front of the engine compartment 20. The vehicle 10 may include any suitable propulsion system, including: 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.

[0020] In some embodiments, vehicle 10 may include an electric, hybrid, or petroleum or gasoline fuel engine, such as a spark-ignition engine. In some embodiments, vehicle 10 may include a diesel fuel engine, such as a compression-ignition engine. Engine compartment 20 houses and / or encloses at least some components of the propulsion system of vehicle 10. Alternatively or additionally, propulsion controls (such as accelerator actuators (e.g., accelerator pedals), brake actuators (e.g., brake pedals), steering wheel, and other such components) are disposed in passenger compartment 18 of vehicle 10. The propulsion controls may be actuated or controlled by the operator of vehicle 10 and may be directly connected to corresponding components of the propulsion system, such as throttle, brakes, vehicle axles, vehicle transmission, etc. In some embodiments, the propulsion controls may transmit signals to a vehicle computer (e.g., drive-by-wire), which in turn may control the corresponding propulsion components of the propulsion system. Therefore, in some embodiments, vehicle 10 may be an autonomous vehicle.

[0021] In some embodiments, vehicle 10 includes a transmission communicated with a crankshaft via a flywheel, clutch, or hydraulic coupler. 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 hybrid vehicle, vehicle 10 may include one or more pistons that operate in cooperation with the crankshaft to generate force, which is transmitted through the transmission to one or more shafts that rotate wheel 22. When vehicle 10 includes one or more electric motors, a vehicle battery and / or fuel cell provide energy to these electric motors to rotate wheel 22.

[0022] Vehicle 10 may include an autonomous vehicle propulsion system, such as cruise control, adaptive cruise control, automatic braking control, other autonomous vehicle propulsion systems, or combinations thereof. Vehicle 10 may 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.

[0023] In some embodiments, vehicle 10 may include an Ethernet component 24, a Controller Area Network (CAN) bus 26, a Media-Oriented System Transport (MOST) component 28, a FlexRay component 30 (e.g., a brake-by-wire system), and a Local Interconnect Network (LIN) component 32. Vehicle 10 may use the CAN bus 26, MOST 28, FlexRay component 30, LIN 32, other suitable network or communication systems, or combinations thereof, to transmit various information from sensors, such as those inside or outside the vehicle, to various processors or controllers, such as those inside or outside the vehicle. Vehicle 10 may include more or fewer features than those generally shown and / or disclosed herein.

[0024] In some embodiments, the vehicle 10 may include a steering system, such as an EPS system, a steer-by-wire system (e.g., which may include one or more controllers or communicate with the one or more controllers, which control components of the steering system without using the mechanical connection between the steering wheel and the wheel 22 of the vehicle 10), a hydraulic steering system (e.g., which may include a magnetic actuator incorporated into a valve assembly of a hydraulic steering system), or other suitable steering systems.

[0025] The steering system may include an open-loop feedback control system or mechanism, a closed-loop feedback control system or mechanism, or a combination thereof. The steering system may be configured to receive various inputs, including but not limited to steering wheel position, input torque, one or more rack or wheel positions, other suitable inputs or information, or combinations thereof.

[0026] Alternatively or concurrently, inputs may include steering wheel torque, steering wheel angle, motor speed, vehicle speed, estimated motor torque command, other suitable inputs, or combinations thereof. The steering system may be configured to provide steering functionality and / or control to the vehicle 10. For example, the steering system may generate auxiliary torque based on various inputs. The steering system may be configured to use the auxiliary torque to selectively control the motor of the steering system to provide steering assistance to the operator of the vehicle 10.

[0027] In some embodiments, the vehicle 10 includes one or more controllers, such as Figure 1B The controller 100 is generally illustrated herein. 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, such as those of the steering system and / or various functions of the vehicle 10. Controller 100 may include a processor 102 and a memory 104. Processor 102 may include any suitable processor, such as the processor described herein. Alternatively or in addition to, or different from, processor 102, controller 100 may also 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 control at least various aspects of the 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.

[0028] Controller 100 may receive one or more signals from various measuring devices or sensors 106 indicative of sensed or measured characteristics of vehicle 10. Sensors 106 may include any suitable sensors, measuring 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. One or more signals may indicate steering wheel torque, steering wheel angle, motor speed, vehicle speed, other suitable information, or combinations thereof. As used herein, “sensor” may correspond to a physical sensor or derived signal (e.g., a signal derived from an algorithm or computation based on one or more sensor inputs directly into the controller or using data transmitted to the controller from a source outside the direct controller area).

[0029] As used herein, "controller" can refer to a hardware module or component including one or more processors or microcontrollers, memory, sensors, one or more actuators, communication interfaces, etc., any part of which can be collectively referred to as "circuit". As described herein, the corresponding functions and steps performed by a given controller, control circuit, etc., can be performed jointly by multiple controllers, processors, etc. For example, "configured to perform" can mean that a single processor, processing device, controller, etc., is configured to perform both A and B, or it can mean that a first processor, first processing device, first controller, etc., is configured to perform A and a second processor, first processing device, first controller, etc., is configured to perform B. For simplicity, "control circuit configured to perform A and B" can mean that one or more processors, processing devices, controllers, etc., are jointly configured to perform A and B. In some examples, one or more functions can be performed remotely (e.g., relative to a vehicle), such as at the controller, processor, circuit, etc., of a remote server, cloud computing system, and / or other remote processing system.

[0030] In some embodiments, controller 100 may perform the methods described herein. However, the methods described herein, as performed by controller 100, are not intended to be limiting, and any type of software executing on a controller, processor, or other circuitry may implement the hysteresis shaping techniques described herein without departing from the scope of this disclosure. For example, a controller (such as a processor executing software within a computing device) may be configured to implement the systems and methods described herein.

[0031] Figure 2AAn example steering system 200 according to this disclosure is illustrated, including a rack or RWA controller 202 and a column or steering wheel actuator (HWA) controller 204 configured to implement RWA position target technology. The HWA controller 204 is configured to generate a steering wheel actuator (HWA) motor torque command based on an estimated rack force (e.g., an estimated rack force signal) received from the RWA controller 202 and one or more other input signals (e.g., vehicle speed, steering wheel position, and steering wheel speed). The RWA controller 202 is configured to determine the estimated rack force based on the motor torque required to achieve or maintain the actual rack / wheel position. Controllers 202 and 204 may correspond to, be implemented by, or correspond to one or more steering system controllers.

[0032] As an example, the HWA controller 204 includes a reference torque calculator 208, which is configured to calculate a reference torque (T) based on an estimated rack force and one or more other input signals. ref For example, the reference torque corresponds to the sum of various inputs / measurements (such as applied force, hysteresis, self-alignment correction or CVR, damping, catch mechanism, 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.

[0033] The estimated rack force corresponds to the measured or estimated torque of the wheel actuator motor. Therefore, the estimated rack force (and any estimated rack force offset or error) is a key factor in determining the force provided by the motor of the steering wheel actuator.

[0034] In some examples, the HWA controller 204 may also 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 a C-factor received from the C-factor lookup module 216. The C-factor may be determined based on a steering wheel angle (“HwAg”) corresponding to driver input and vehicle speed (e.g., a steering wheel angle indicating the driver’s intention conveyed via the steering wheel). An example system and method for obtaining a rack position reference and a C-factor are described in more detail in U.S. Patent Application No. 18 / 318,657, filed May 16, 2023, the entire contents of which are incorporated herein by reference.

[0035] RWA controller 202 includes rack position controller 224 (e.g., PID rack position controller) configured to generate one or more rack position control signals based on the actual rack position and a rack position reference (e.g., a rack position error based on the difference between the actual rack position and the rack position reference). For example, rack position control signals may include, but are not limited to, rack motor speed and motor torque commands (e.g., signals indicating the amount of torque applied by the driver). In this way, the rack position is controlled to follow the driver's intention (as indicated by the rack reference position). In some examples, rack position controller 224 may be configured to further control the rack position based on a target rack position. For example, the rack position reference may correspond to an ideal / desired steering response. Conversely, the target rack position may correspond to an actual target position where the steering rack should move. In other words, the target rack position may be determined in part based on the rack position reference, but may be adjusted or limited according to hardware or software constraints, vehicle dynamics, safety, etc.

[0036] The rack force predictor 226 generates an estimated rack force based on the output of the rack position controller 224 (e.g., a function of the rack motor speed, rack motor torque commands, etc.). In various examples, the estimated rack force can be used to provide steering wheel torque resistance to the driver via the HWA. As shown, the rack force predictor 226 can output the estimated rack force, and a 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 this 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.

[0037] 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, allowing the steering wheel to be controlled to rotate in a manner consistent with the rotation of the wheels when the steering wheel is released.

[0038] The reference torque can correspond to the desired, ideal, or target torque that the driver (i.e., at the steering wheel) will feel. As described above, the reference torque is calculated based on inputs including, but not limited to, driver input (e.g., input torque corresponding to the steering wheel angle), road conditions, damping, hysteresis, etc. (e.g., via HWA) to control the torque at the steering wheel to match the reference torque. For example, the outputs of one or more sensors measuring the actual torque at the wheels are used to minimize the difference between the reference torque and the actual torque.

[0039] The force application function (e.g., the force application function implemented by the reference torque calculator 208) defines the relationship between driver input (e.g., the force or torque applied by the driver to the steering wheel, which may be referred to as "force") and the response (i.e., movement) of the steering system. For example, the force application function may output a force value based on a lookup table or other function (e.g., by using an estimated rack load as input). The estimated rack load may be modified before being input into the lookup table by adding the calculated return load value to the estimated rack load. The force application function indicates the amount of force required by the driver to elicit the desired response.

[0040] The steering system and method according to this disclosure (e.g., steering system 200) are configured to implement RWA position target techniques to generate an adjusted or modified RWA target that minimizes the position error or misalignment between the HWA and RWA, as described in more detail below. For example, one or more functions of the systems and methods described below can be implemented by an HWA controller 204 (such as by a rack position reference calculator 220) and / or an RWA controller (such as by a rack position controller 224). In one example, the rack position reference calculator 220 and the rack position controller 224 can be configured to perform the corresponding functions of the techniques described below.

[0041] As an example, the steering system 200 according to this disclosure is configured to provide target adjustments to the wheel actuator position when the position / position error between the wheel actuator and the steering wheel actuator is too large (e.g., exceeding a position error threshold). These adjustments allow the vehicle to meet the following performance criteria in the presence of position errors:

[0042] Ensure the wheels are moving in the same direction as the steering wheel speed;

[0043] When the steering wheel stops moving, the wheels also stop moving;

[0044] Moving the wheels in a controlled and predictable manner, minimizing or preventing excessive or insufficient movement; and

[0045] Reduce positional errors.

[0046] Figure 2B This is a functional block diagram illustrating an example implementation of the functions and / or components of the steering system and method of this disclosure. For example, one or more components of the RWA controller 202 and / or HWA controller 204 (such as rack position reference calculator 220 and rack position controller 224) may be configured to implement... Figure 2B The functions shown. For simplicity, as... Figure 2B As shown, these functions are generally described as components and / or functions of the steering system 200. For example, the RWA controller 202 and / or HWA controller 204 may respectively include or implement one or more of the following: wheel offset gain calculation module 230, wheel gain limit calculation module 234, offset calculation module 238, magnitude limit application module 242, wheel position target switch state module 246, and wheel position control module 250, as described in more detail below.

[0047] Wheel offset gain calculation module 230 is configured to generate and output wheel offset gain (or gain signal). For example, module 230 can determine whether the wheel position is ahead of the wheel position target (leading) or behind the wheel position target (lagging) (rack tracking state, such as "wheel ahead" or "wheel lagging"), and generate wheel offset gain accordingly. As an example, the wheel offset gain is calculated based on one or more of the following: rack position error, vehicle speed and current C-factor or C-factor estimate, percentage gain based on rack-based C-factor estimate, rack tracking state, etc.

[0048] As an example, the current rack-based C-factor estimate can be estimated by dividing the change in the actual rack position by the change in the rack-based steering angle target (in revolutions). The rack-based C-factor estimation gain percentage can be applied as a proportional scalar to the estimated rack-based C-factor to set increasing and decreasing gains corresponding to wheel lag and wheel lead states, respectively. The rack tracking state can be determined by multiplying the sign of the wheel error by the sign of the steering wheel speed, where the wheel error equals the measured wheel position minus the initial / actual wheel position target. When these signs are multiplied, a positive value indicates the wheel is lagging behind the target, while a negative value indicates the wheel is leading the target. In this way, different gains can be selected for the wheel offset gain using the product of the signs (state indicators).

[0049] Wheel offset gain limit calculation module 234 is configured to calculate one or more wheel offset gain limits or limiters and apply them to the wheel offset gain to obtain a limited wheel offset gain. For example, module 234 limits the gain to a maximum and a minimum value (e.g., a value between a maximum and a minimum limit), which can depend on various calibrations, vehicle dynamics (e.g., vehicle dynamics estimation), etc. Vehicle dynamics estimation can include a vehicle bicycle model, vehicle speed-based calibration, dual-track vehicle model, etc. The rack gain conversion rate can be applied to limit the rate of change of rack gain (e.g., using a closed-loop speed controller, a rack speed-based scalar, a rack speed-based calibration gain or offset, and one or more rack speed-based limiters). In some examples, the estimated C-factor / steering ratio may affect both the maximum and minimum limits.

[0050] Offset calculation module 238 is configured to calculate an offset and apply it to the measured rack position to obtain and output a target wheel position (raw or unmodified). For example, the offset can be proportional to the steering wheel speed, the target adjustment gain (i.e., a limited wheel offset gain), the software execution time step, and the calibrable device gain adjustment. Therefore, the offset can be calculated by multiplying the offset gain by the steering wheel speed, the time step, and the calibrable gain. The offset can then be added to the measured rack position (e.g., the current rack position).

[0051] For example, the executable time step of the software can be a calibrable value or a dynamically calculated estimate of the execution time difference. Device gain can be a calibrable or predetermined value, calibrated based on vehicle dynamics inputs (vehicle speed, yaw rate, lateral acceleration, etc.), a calculated device tracking capability model, etc. In other examples, device gain can be based on rack speed, closed-loop control (e.g., PID or LQR control systems), etc. Steering wheel speed can be estimated as the change in steering wheel position relative to time or relative to a time step, and can include units including degrees per second, radians per second, or revolutions per second.

[0052] The quantity limit application module 242 is configured to apply further limiters or limits to the original wheel position target to obtain and output a restricted wheel position target. For example, module 242 can calculate and apply one or more limits using dynamic limits based on a vehicle model, caliable limits related to vehicle speed, or constant quantity limits, and can estimate minimum and maximum wheel positions based on permissible vehicle horizontal dynamics metrics. The vehicle dynamics model may include a bicycle model, a dual-track model, and / or vehicle speed-related estimates. The vehicle dynamics metrics may include at least one of permissible vehicle lateral acceleration error, permissible vehicle yaw rate error, permissible vehicle lateral position error, permissible vehicle lateral velocity error, and / or permissible vehicle yaw acceleration error.

[0053] The wheel position target switch state module 246 can selectively activate or deactivate the application / use of (restricted / adjusted) wheel position targets. In other words, depending on various conditions, the wheel position target calculated according to the technology of this disclosure may or may not be used. When not in use, an initial or actual position target (i.e., an initial, unmodified / unadjusted position target) may be used. For example, under certain conditions, an adjusted wheel position target with an offset applied using the technology of this disclosure may not be used.

[0054] As an example, module 246 may: in response to a rack position error exceeding a rack position error threshold or a vehicle speed-related rack position error threshold; based on a vehicle-based model-based rack error allowable estimate; in response to a wheel speed error exceeding a wheel speed error threshold; and / or in response to a wheel acceleration exceeding a wheel acceleration threshold, activate / apply an adjusted wheel position target.

[0055] Wheel position control module 250 calculates and outputs wheel position control signals (e.g., controlling the RWA to move the rack based on the adjusted wheel position target) based on the adjusted wheel position target. As an example, module 250 implements a blending function to smoothly transition from an initial wheel position target to an adjusted wheel position target, or vice versa. The blending function may include a limiting mechanism configured to limit or restrict the adjusted wheel position target based on the initial wheel target command magnitude, steering wheel speed, wheel error direction, and / or the adjusted wheel target command. The blending function may include a timing transition triggered when a source switch (e.g., activated by wheel position target switch state module 246) is detected. During the transition state (e.g., when transitioning between the initial and adjusted wheel position targets), the position target may be transitioned, blended, or adjusted based on a time-dependent transition rate, a filtered transition, and / or an error-dependent percentage gain offset.

[0056] In some examples using the techniques described herein, the adjusted wheel position target is calculated according to the following formula:

[0057] Rack Pos Target Adj = Rack Pos Actual + Alignment Offset, where Rack PosTarget Adj is the adjusted wheel position target, Rack Pos Actual is the initial or actual rack position, and Alignment Offset is the offset (e.g., calculated by offset calculation module 238).

[0058] The alignment offset can be calculated using the following formula:

[0059] Alignment Offset = Gain * Steering wheel speed * Sampling time.

[0060] The gain can be calculated as a function of rack position error (Rack Pos Error), steering wheel position (Hw Pos), steering wheel speed (Hw Vel), and vehicle speed (VehSpeed):

[0061] Gain=fn(Rack Pos Error, Hw Pos, Hw Vel, VehSpeed).

[0062] Therefore, as described herein, the target offset gain depends on whether the wheels are ahead or behind the target wheel position, such that the target offset gain increases when the wheels are behind and decreases when the wheels are ahead. This helps the function reduce position errors more quickly and enhances flexibility, smoothness, and control. If the rack is behind the ideal rack position, the gain is scaled up and limited by stability-based limits. If the rack is ahead of the ideal rack position, the gain is scaled down and limited based on the minimum rack movement that the driver can intuitively use to control the vehicle at a given steering wheel speed. The target offset gain includes at least one magnitude or rate of change limiter that protects the wheel position target adjustment calculation by adding safety limits to ensure safe and controllable rack movement by the driver's input. The final alignment offset may be limited by rack actuator endpoint limits, vehicle dynamics-based limits that take into account actuator protection, and vehicle stability.

[0063] Furthermore, the original dynamic value limiter for wheel position target adjustment enhances safety by mitigating hazards by limiting software output in the event of a software failure. Rack speed feedback can be used to manage or limit rack speed while the adjusted wheel position target actively changes commands. In this way, these techniques ensure that the wheel controller does not move too fast to meet the adjusted wheel position target.

[0064] Figure 3 This is a flowchart generally illustrating a method 300 for performing wheel position control technology according to the principles of this disclosure. For example, one or more computing devices, processors, or processing devices are configured to execute instructions to implement method 300, such as one or more processors in a system described herein (e.g., a computing device or processor of a vehicle configured to implement controller 100, system 200, etc.). In some examples, one or more steps of method 300 as described below may be skipped or omitted, and / or one or more of these steps may be performed in a different order than described.

[0065] At 304, method 300 includes obtaining a wheel offset gain. For example, the wheel offset gain is calculated based at least in part on the determination of whether the wheel position is ahead of or behind the wheel position target (leading) or lags behind the wheel position target (lagging). At 308, method 300 includes applying an offset gain limit to the wheel offset gain.

[0066] At 312, method 300 includes calculating an offset and applying that offset to the measured rack position to obtain and output a target wheel position. For example, the offset may be calculated based at least on the wheel offset gain and steering wheel speed. Applying the offset involves adding the offset to the measured rack position.

[0067] At 316, method 300 includes obtaining a magnitude limit and applying the magnitude limit to a wheel position target to obtain an adjusted wheel position target. At 320, method 300 includes selectively activating / enabling the adjusted wheel position target.

[0068] At 324, method 300 includes using an adjusted wheel position target to obtain a wheel position control signal. For example, obtaining the wheel position control signal may include applying a blending or hybrid function to transition between an initial wheel position target and an adjusted wheel position target, i.e., from the initial wheel position target to the adjusted wheel position target or from the adjusted wheel position target to the initial wheel position target. In other words, the transition may be performed gradually over a predetermined time period, rather than abruptly or instantaneously stepping from the initial wheel position target to the adjusted wheel position target. At 328, method 300 includes controlling the RWA based on the wheel position control signal.

[0069] The foregoing discussion is intended to illustrate the principles and various embodiments of this disclosure. Once the foregoing disclosure is fully understood, many variations and modifications will become apparent to those skilled in the art. The appended claims are intended to be construed as covering all such variations and modifications.

[0070] The word “example” is used herein to indicate that something is used as 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. Rather, the use of the word “example” is intended to present the concept in a specific manner. As used herein, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless otherwise specified or clearly understood from the context, “X comprises A or B” is intended to mean any of the natural inclusive permutations and combinations. That is, if X comprises A; X comprises B; or X comprises both A and B, then “X comprises A or B” is satisfied in any of the foregoing examples. Additionally, the articles “a” and “an” as used herein and in the appended claims should be generally interpreted as meaning “one or more” unless otherwise specified or clearly understood from the context to refer to the singular form. Furthermore, the use of the terms “one embodiment” or “an embodiment” throughout is not intended to refer to the same embodiment or implementation unless specifically described as such. As used herein, the term “approximate” may correspond to “...within + / - 5.0%”.

[0071] The systems, algorithms, methods, instructions, etc., described herein can be implemented in hardware, software, or any combination thereof. Hardware may include, for example, computers, intellectual property (IP) cores, application-specific integrated circuits (ASICs), programmable logic arrays, optical processors, programmable logic controllers, microcode, microcontrollers, servers, microprocessors, digital signal processors, or any other suitable circuitry. In the claims, the term "processor" should be understood to cover any of the aforementioned hardware, individually or in combination. The terms "signal" and "data" are used interchangeably.

[0072] As used herein, the term "module" can include packaged functional hardware units designed for use with other components, instruction sets executable by a controller (e.g., a processor executing software or firmware), processing circuitry configured to perform specific functions, and stand-alone hardware or software components interfacing with a larger system. For example, a module can include application-specific integrated circuits (ASICs); field-programmable gate arrays (FPGAs); circuits; digital logic circuits; analog circuits; combinations of discrete circuits; gates; and other types of hardware; or combinations thereof. In other embodiments, a module can include memory storing instructions executable by a controller to implement the features of the module.

[0073] Furthermore, in one aspect, for example, the systems described herein can be implemented using a general-purpose computer or general-purpose processor with a computer program that, when executed, implements any of the various methods, algorithms, and / or instructions described herein. Alternatively or alternatively, for example, a special-purpose computer / processor can be utilized, which may include additional hardware for implementing any of the methods, algorithms, or instructions described herein.

[0074] Furthermore, all or part of the embodiments of this disclosure may 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 may be any device capable of, for example, tangibly containing, storing, transmitting, or transporting a program for use by or in conjunction with any processor. Such a medium may be, for example, an electronic, magnetic, optical, electromagnetic, or semiconductor device. Other suitable media are also available.

[0075] The above embodiments, implementations, and aspects have been described to allow for an easy understanding of this disclosure and are not intended to limit it. Rather, this disclosure is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, and its scope should be interpreted in the broadest possible sense to cover all such modifications and equivalent structures permitted under the law.

Claims

1. A method for controlling wheel position in a steer-by-wire system of a vehicle, the method comprising using one or more processors: Receive rack position error, which indicates the difference between the actual rack position and the rack position reference. The alignment offset is generated based on the rack position error; An adjusted wheel position target is generated based on the alignment offset; as well as The wheel actuator is controlled based on the adjusted wheel position target.

2. The method of claim 1, further comprising generating the alignment offset based on wheel offset gain.

3. The method of claim 2, further comprising generating the wheel offset gain based on at least one of the rack position error, steering wheel position, steering wheel speed, and vehicle speed.

4. The method of claim 2, further comprising generating the wheel offset gain based on determining whether the wheel position is ahead of or behind the wheel position target.

5. The method of claim 2, further comprising limiting the wheel offset gain based on the vehicle's dynamic state.

6. The method according to claim 1, wherein, The alignment offset is also generated based on at least one of steering wheel speed, sampling time, and calibrable gain.

7. The method of claim 1, further comprising selectively limiting the adjusted wheel position target based on the vehicle's dynamic state.

8. The method of claim 1, further comprising selectively enabling the adjusted wheel position target based on at least one of a rack position error threshold, a rack or wheel speed error threshold, and a rack or wheel acceleration threshold.

9. The method of claim 1, further comprising transitioning from an initial wheel position target command to the adjusted wheel position target within a predetermined time period.

10. A processor configured to execute instructions stored in memory, wherein, Executing the instructions causes the processor to control the wheel positions of the vehicle's steer-by-wire system by: Receive rack position error, which indicates the difference between the actual rack position and the rack position reference. The alignment offset is generated based on the rack position error; An adjusted wheel position target is generated based on the alignment offset; as well as The wheel actuator is controlled based on the adjusted wheel position target.

11. The processor of claim 10, wherein the instructions further cause the processor to generate the alignment offset based on wheel offset gain.

12. The processor of claim 11, wherein the instructions further cause the processor to generate the wheel offset gain based on at least one of the rack position error, steering wheel position, steering wheel speed, and vehicle speed.

13. The processor of claim 11, wherein the instructions further cause the processor to generate the wheel offset gain based on a determination of whether the wheel position is ahead of or behind the wheel position target.

14. The processor of claim 11, wherein the instructions further cause the processor to limit the wheel offset gain based on the vehicle's dynamic state.

15. The processor according to claim 10, wherein, The alignment offset is also generated based on at least one of steering wheel speed, sampling time, and calibrable gain.

16. The processor of claim 10, wherein the instructions further cause the processor to selectively limit the adjusted wheel position target based on the vehicle's dynamic state.

17. The processor of claim 10, wherein the instructions further cause the processor to selectively enable the adjusted wheel position target based on at least one of a rack position error threshold, a rack or wheel speed error threshold, and a rack or wheel acceleration threshold.

18. The processor of claim 10, wherein the instructions further cause the processor to switch from an initial wheel position target command to the adjusted wheel position target within a predetermined time period.

19. A steer-by-wire system for a vehicle, the steer-by-wire system comprising: The processor is configured to execute instructions stored in memory, wherein executing the instructions causes the processor to control the wheel position by: Receive rack position error, which indicates the difference between the actual rack position and the rack position reference. The alignment offset is generated based on the rack position error; An adjusted wheel position target is generated based on the alignment offset; and The wheel actuator is controlled based on the adjusted wheel position target.

20. The steer-by-wire system according to claim 19, wherein, Executing the instructions also causes the processor to: The alignment offset is generated based on the wheel offset gain; The wheel offset gain is generated based on at least one of the rack position error, steering wheel position, steering wheel speed, vehicle speed, and the determination of whether the wheel position is ahead of or behind the wheel position target.

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