COMPENSATION OF AN ESTIMATED RACK FORCE MISALIGNMENT

Abstract

A method for controlling a steering system of a vehicle includes obtaining a plurality of values ​​corresponding to operation of the steering system, determining an estimated rack force based on the plurality of values, separately determining a long-term (LT) offset factor of the estimated rack force and a short-term (ST) offset factor of the estimated rack force, determining a total compensation value based on a combination of the ST offset factor and the ST offset factor, applying the total compensation value to the estimated rack force to obtain a compensated estimated rack force, and controlling at least one function of the steering system using the compensated estimated rack force.

Description

TECHNICAL FIELD

[0001] This disclosure relates to a method, system, and processing apparatus for obtaining an accurate rack force estimate for a steering system of a vehicle. BACKGROUND OF THE INVENTION

[0002] A vehicle, such as a car, truck, sport utility vehicle, crossover, minivan, personal watercraft, aircraft, off-road vehicle, recreational vehicle, or other suitable means of transportation, typically includes a steering system, such as an electronic 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 a driver of the vehicle, controlling steerable wheels of the vehicle, and the like.

[0003] Known methods and systems can be found, for example, in the documents DE 10 2017 105 370 A1, DE 10 2008 042 666 A1, DE 10 2023 102 609 A1 and DE 10 2006 022 663 A1.

[0004] DE 10 2017 105 370 A1 discloses a method for determining a rack force.

[0005] DE 10 2008 042 666 A1 teaches to generate a total steering force error from an estimated actual rack force and an estimated target rack force in order to compensate for disturbances.

[0006] DE 10 2023 102 609 A1 discloses a method for compensating a disturbance in a rack force.

[0007] DE 10 2006 022 663 A1 discloses a method for improving the straight-line stability of a vehicle. SUBJECT OF THE INVENTION

[0008] This disclosure generally relates to cooperative vehicle operation and lateral control of vehicles.

[0009] One aspect of the disclosed embodiments includes a method for controlling a steering system of a vehicle. The method includes obtaining a plurality of values ​​corresponding to the operation of the steering system, determining an estimated rack force based on the plurality of values, separately determining a long-term (LT) offset factor of the estimated rack force and a short-term (ST) offset factor of the estimated rack force, determining a total compensation value based on a combination of the ST offset factor and the ST offset factor, applying the total compensation value to the estimated rack force to obtain a compensated estimated rack force, and controlling at least one function of the steering system using the compensated estimated rack force.

[0010] In other aspects, a system for controlling one or more steering functions of a vehicle is configured to perform the methods described herein. In other aspects, a processing device is configured to execute instructions stored in a memory to control one or more steering functions of a vehicle as described herein.

[0011] These and other aspects of the present disclosure are disclosed in the following detailed description of the embodiments, the appended claims, and the accompanying figures. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, in accordance with common practice, the various features in the drawings are not to scale. On the contrary, the dimensions of the various features are arbitrarily exaggerated or reduced for clarity. Fig. 1A generally shows a vehicle according to the principles of the present disclosure. Fig. 1B generally shows a controller according to the principles of the present disclosure. Fig. 2 generally illustrates an exemplary rack or road wheel actuator controller and a hand wheel actuator controller of a steer-by-wire system in accordance with the principles of the present disclosure. Fig. 3 generally illustrates an example implementation of a road wheel actuator controller estimated rack force offset compensation module in accordance with the principles of the present disclosure. Fig. 4 generally illustrates steps of an exemplary method for compensating for estimated rack force offset in accordance with the principles of the present disclosure. DETAILED DESCRIPTION

[0013] The following discussion relates to various embodiments of the disclosure. Although one or more of these embodiments may be preferred, the disclosed embodiments should not be interpreted or otherwise used as limiting the scope of the disclosure, including the claims. Furthermore, those skilled in the art will understand that the following description has broad application, and that the discussion of any embodiment is intended only as exemplary of that embodiment and is not intended to imply that the scope of the disclosure, including the claims, is limited to that embodiment.

[0014] As described, a vehicle, such as a passenger car, truck, sport utility vehicle, crossover, minivan, watercraft, aircraft, off-road vehicle, recreational vehicle, or other suitable means of transportation, typically includes a steering system, such as an electronic 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 vehicle's driver, controlling steerable wheels of the vehicle, and the like.

[0015] In a self-steering steering system, rack force refers to the force transmitted to the vehicle's wheels (e.g., via a rack and pinion) when the driver turns the steering wheel. Rack force can be calculated or estimated (e.g., as an estimated rack force). The estimated rack force signal can be used to provide accurate steering response, provide feedback to the driver, improve vehicle stability, and more.

[0016] An offset or error in the estimated rack force (i.e., an offset between the actual and estimated rack force) can cause vehicle pull or other feel / feedback issues. Estimated rack force offset can be caused by various offset factors, including, but not limited to, short-term offset factors such as cambered or other uneven road surfaces or conditions, crosswinds, etc., and long-term offset factors such as RWA (road wheel actuator system) friction, chassis misalignment, offsets or errors in various input signals (e.g., torque signals, position signals, etc.), and / or other vehicle issues.Accordingly, the estimated rack force offset, as an indicator of the difference between actual and estimated rack force, may vary over time and under different vehicle operating conditions.

[0017] For example, a residual position and / or friction error of the RWA system results in an estimated rack force offset. The estimated rack force offset then causes (i) a force offset, resulting in unbalanced steering effort and pull on the vehicle, and / or (ii) an RWA position tracking command offset, resulting in pull on the vehicle.

[0018] Estimated rack force offset compensation systems and methods according to the present disclosure are configured to determine (e.g., calculate, model, etc.) an accurate estimated rack force offset and control various functions of the steering system accordingly. For example, short-term and long-term offset factors are determined separately so that the estimated rack force offset accounts for the variability of the offset factors.

[0019] In a sample implementation, the rack load distortion is filtered out from various measurement signals when certain conditions are met (e.g., when the vehicle is traveling straight and various signals / measurements are greater or less than respective thresholds) before being converted into steering torque feedback. In other words, the learning of the estimated rack force offset is performed while traveling straight ahead. This allows offset factors (e.g., both long-term and short-term offset factors) to be obtained when the effects of various other inputs are minimized.

[0020] In some examples, the techniques described here can be combined with an active traction compensation function. An example active traction compensation function or feature corrects vehicle traction problems by compensating for handwheel torque offsets detected by the steering system. These torque offsets can include the short-term and long-term offset factors described here. When offset factor compensation is applied, the need for the driver to provide a constant input torque to counteract these offsets is greatly reduced.

[0021] As described here, the short-term offset factors may correspond to conditions external to the vehicle. Accordingly, short-term correction or compensation values ​​may be determined relatively quickly and applied only during a current ignition cycle. For example, the short-term compensation values ​​or data are not stored between ignition cycles. In some examples, the short-term correction data may be reset within the current ignition cycle in response to detected changes in driving conditions (e.g., handwheel torque, handwheel position, rack position, rack force, lateral acceleration, and / or yaw rate exceeding corresponding thresholds).

[0022] Conversely, long-term offset factors may be related to vehicle issues (e.g., internal vehicle conditions, associated vehicle systems and sensors, etc.). Since long-term offset factors are typically related to the vehicle itself and not the driving / operating environment, long-term offset factors are corrected relatively slowly (i.e., compared to short-term offset factors). Accordingly, long-term compensation values ​​or data can be stored and used in subsequent ignition cycles. In one example, a total offset compensation value is a sum of short-term and long-term compensation values / terms. The total compensation value can be scaled based on vehicle speed before being applied to the steering system.

[0023] Fig. 1A generally illustrates a vehicle 10 in accordance with the principles of the present disclosure. The vehicle 10 may be any suitable vehicle, such as a car, a truck, a sport utility vehicle, a minivan, a crossover, any other passenger vehicle, a suitable commercial vehicle, or any other suitable vehicle. Although the vehicle 10 is illustrated as a wheeled passenger vehicle for use on roads, the principles of the present disclosure may also apply to other vehicles, such as aircraft, boats, trains, drones, or other suitable vehicles.

[0024] 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 the hood 14 provides access to the engine compartment 20 when the hood 14 is in a first, or open, position, and the hood 14 covers the engine compartment 20 when the hood 14 is in a second, or closed, position. In some embodiments, the engine compartment 20 may be located at a rear portion of the vehicle 10, other than as generally illustrated.

[0025] The passenger compartment 18 may be located behind the engine compartment 20, but may also be located forward of the engine compartment 20 if the engine compartment 20 is located in the rear of the vehicle 10. The vehicle 10 may include any suitable propulsion system, including an internal combustion engine, one or more electric motors (e.g., an electric vehicle), one or more fuel cells, a hybrid propulsion system (e.g., a hybrid vehicle) comprising a combination of an internal combustion engine and one or more electric motors, and / or any other suitable propulsion system.

[0026] In some embodiments, the vehicle 10 may include a gasoline engine, e.g., a spark-ignition engine. In some embodiments, the vehicle 10 may include a diesel 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 pedal, a brake pedal, a handwheel, and other such components are disposed within 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 the corresponding components of the propulsion system, such as a throttle, a brake, a vehicle axle, a vehicle transmission, and the like. In some embodiments, the propulsion controls may send signals to a vehicle computer (e.g.,Drive-by-Wire), which in turn can control the corresponding drive component of the drive system. Thus, in some embodiments, vehicle 10 can be an autonomous vehicle.

[0027] In some embodiments, the vehicle 10 includes a transmission connected to a crankshaft via a flywheel, a clutch, or a fluid coupling. In some embodiments, the transmission includes a manual transmission. In some embodiments, the transmission includes an automatic transmission. The vehicle 10, in the case of an internal combustion engine or a hybrid vehicle, may include one or more pistons that cooperate with the crankshaft to generate power that is transmitted through the transmission to one or more axles that rotate the wheels 22. If the vehicle 10 has one or more electric motors, a vehicle battery and / or a fuel cell provides power to the electric motors to rotate the wheels 22.

[0028] Vehicle 10 may include automatic vehicle propulsion systems, such as cruise control, adaptive cruise control, automatic braking control, other automatic vehicle propulsion systems, or a combination thereof. Vehicle 10 may be an autonomous or semi-autonomous vehicle or other suitable vehicle type. Vehicle 10 may include additional or fewer features than those generally illustrated and / or disclosed herein.

[0029] In some embodiments, the vehicle 10 may include an Ethernet component 24, a Controller Area Network bus (CAN bus) 26, a Media Oriented Systems Transport (MOST) component 28, a FlexRay component 30 (e.g., brake-by-wire system and the like), and a Local Interconnect Network (LIN) component 32. The vehicle 10 may use the CAN bus 26, the MOST component 28, the FlexRay component 30, the LIN component 32, other suitable networks or communication systems, or a combination thereof, to communicate various information from, e.g., sensors inside or outside the vehicle to, e.g., various processors or control units inside or outside the vehicle. The vehicle 10 may include additional or fewer features than those generally illustrated and / or disclosed herein.

[0030] In some embodiments, the vehicle 10 may include a steering system, such as an EPS system, a steer-by-wire steering system (which may, for example, include or communicate with one or more controllers that control components of the steering system without the use of a mechanical connection between the handwheel and the wheels 22 of the vehicle 10), a hydraulic steering system (which may, for example, include a magnetic actuator integrated into a valve assembly of the hydraulic steering system), or other suitable steering system.

[0031] The steering system may include an open-feedback system or mechanism, a closed-feedback system or mechanism, or a combination thereof. The steering system may be configured to receive various inputs, including, but not limited to, a handwheel position, an input torque, one or more road wheel positions, other suitable inputs or information, or a combination thereof.

[0032] Additionally or alternatively, the inputs may include a handwheel torque, a handwheel angle, a motor speed, a vehicle speed, an estimated motor torque command, another suitable input, or a combination thereof. The steering system may be configured to perform the steering function and / or control of the vehicle 10. For example, the steering system may generate an assist torque based on the various inputs. The steering system may be configured to selectively control a motor of the steering system using the assist torque to provide steering assistance to the driver of the vehicle 10.

[0033] In some embodiments, the vehicle 10 may include a controller, such as controller 100, as generally described in Fig. 1B. The controller 100 may be any suitable controller, such as an electronic control unit or other suitable controller. The controller 100 may be configured to control, for example, the various functions of the steering system and / or various functions of the vehicle 10. The controller 100 may include a processor 102 and a memory 104. The processor 102 may be any suitable processor as described herein. Additionally or alternatively, the controller 100 may include any suitable number of processors in addition to the processor 102 or may include other processors. The memory 104 may include a single disk or a plurality of disks (e.g., hard drives) and includes a memory management module that manages one or more partitions within the memory 104.In some embodiments, memory 104 may include flash memory, solid-state memory, or the like. Memory 104 may be 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 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.

[0034] Controller 100 may receive one or more signals from various gauges or sensors 106 indicative of sensed or measured characteristics of vehicle 10. Sensors 106 may include any suitable sensors, gauges, and / or other suitable mechanisms. For example, sensors 106 may include one or more torque sensors or devices, one or more handwheel 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 a combination thereof. The one or more signals may indicate handwheel torque, handwheel angle, motor speed, vehicle speed, other suitable information, or a combination thereof.

[0035] In some embodiments, controller 100 may be configured to implement the estimated rack force offset compensation systems and methods of the present disclosure. However, the systems and methods described herein as implemented by controller 100 are not intended to be limiting, and any type of software executing on a controller or processor may perform the methods described herein without departing from the scope of this disclosure. For example, a controller, such as a processor executing software on a computing device, may perform the methods described herein.

[0036] Fig. Figure 2 shows an example of a rack or RWA controller 200 and a steering column or handwheel actuator (HWA) controller 204 of a steering system according to the present disclosure. For example, the HWA controller 204 is configured to generate a handwheel actuator motor torque command based on an estimated rack force (e.g., an estimated rack force signal) received from the RWA controller 200 and one or more other input signals (e.g., vehicle speed, handwheel position, and handwheel speed). The RWA controller 200 is configured to determine the estimated rack force based on an actual rack position (e.g., a signal indicative of the actual rack position) and a rack position reference signal (e.g., a rack position reference indicative of a target rack position).

[0037] For example, the HWA controller 204 includes a reference torque calculator 208 configured to calculate a reference torque based on the estimated rack force and one or more other input signals. The reference torque may, for example, be a sum of various inputs / measurements such as force, hysteresis, damping reset, catch, etc. A closed-loop torque controller 212 (e.g., a PID control loop) is configured to generate and output the motor torque command based at least in part on the reference torque. The motor torque command is provided as a control signal to control a motor of the handwheel actuator.

[0038] The estimated rack force corresponds to a target value for the motor torque command. Accordingly, the estimated rack force (and any offset or error in the estimated rack force) is a critical factor in determining the force provided by the handwheel actuator motor.

[0039] 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 the 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 handwheel angle ("HwAg") corresponding to the driver input (e.g., a handwheel angle indicative of driver intent conveyed via the handwheel). Example systems and methods for determining the rack position reference and the 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.

[0040] The RWA controller 200 includes a rack position controller 224 (e.g., a PID rack position controller) 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 a difference between the actual rack position and the rack position reference). The rack position control signals may include, but are not limited to, signals for the rack motor speed and the motor torque command (e.g., indicative of the amount of torque applied by the driver). In this way, the rack position is controlled to follow the driver's intent (as indicated by the rack reference position).

[0041] A rack force predictor 228 generates the estimated rack force based on the outputs of the rack position controller 224 (e.g., based on a function of the rack motor speed, the rack motor torque command, etc.). In various examples, the estimated rack force may be calculated based on the amount of torque applied by the driver to the handwheel (as indicated by the rack motor torque command, various sensor signals, etc.).

[0042] As described herein, the estimated rack force typically includes an offset or error (e.g., an offset of the estimated rack force). The RWA controller 200 according to the present disclosure includes an offset compensation module 232 configured to determine an accurate offset of the estimated rack force (a compensated offset of the estimated rack force) and modify the estimated rack force accordingly, as described in more detail below.

[0043] Fig. Figure 3 shows an example implementation of the offset compensation module 232. In some examples, the offset compensation module 232 is configured to receive long-term and short-term offset factors during a learning mode or period. For example, learning the long-term and short-term offset factors may be contingent upon one or more enabling conditions being met. The enabling conditions may correspond to driving and vehicle conditions where the long-term and short-term offset factors can be accurately calculated and the deviation is minimized. The enabling criteria may include, but are not limited to: The maximum handwheel torque is less than a threshold; The angle of the handwheel is smaller than a threshold; The rack position is less than a threshold; The calculations of the handwheel angle and the rack position correspond to the respective minimum confidence values; The handwheel speed is less than a threshold; The rack speed is less than a threshold value; The vehicle speed is within a specified range (e.g. between minimum and maximum values); The rate of change of vehicle speed is less than a threshold; The lateral speed of the vehicle is less than a threshold value; The yaw rate of the vehicle is less than a threshold value; and The rack force is less than a threshold value.

[0044] In response to the satisfaction of selected enabling conditions (e.g., some or all of the conditions listed above), the offset compensation module 232 obtains the long-term (LT) and short-term (ST) offset factors based on the estimated rack force and, in some examples, various other input signals (sensor signals, measurement signals, etc.). For example, the offset compensation module 232 includes an LT filter module 304 and an ST filter module 308, which may correspond to respective low-pass filters or filter circuits. Each of the filter modules 304 and 308 filters out various low-frequency elements corresponding to the estimated rack force to obtain the respective LT and ST offset factors. For example, the filter modules 304 and 308 correspond to low-pass filters with different gains and cutoff frequencies.Accordingly, the LT filter module 304 may learn the LT offset factor over a first learning period, while the ST filter module 308 generates the ST offset factor learned over a second learning period shorter than the first learning period. The first and second learning periods may be defined by corresponding calibration values.

[0045] In one example, the output of the LT filter module 304 (i.e., the LT offset factor) is the result of filtering out the low-frequency elements of the estimated rack force and may include higher-frequency elements associated with ST errors. Conversely, the output of the ST filter module 304 is the result of filtering out the low-frequency elements of the estimated rack force and the elements associated with LT errors. In other words, the ST filter module 308 may have a higher frequency than the LT filter module 304.

[0046] The LT offset factor and the ST offset factor are each provided to an LT offset compensation module 312 and an ST offset compensation module 316, which output LT and ST offset compensation values, respectively. The LT and ST offset compensation values ​​are calculated based on the LT and ST offset factors. The LT and ST compensation values ​​are combined (e.g., summed in summing module 320) to generate a compensated estimated rack force offset. The estimated rack force is modified / adjusted based on the compensated estimated rack force offset. For example, the compensated estimated rack force offset is subtracted from (or, in some examples, added to) the estimated rack force to obtain a compensated estimated rack force according to the present disclosure.The compensated estimated rack force is provided to the HWA controller 204 for calculating the engine torque command as described above.

[0047] In some examples, the compensated estimated rack force offset may be scaled based on vehicle speed (e.g., multiplied by a scaling factor that increases with speed) and / or not applied at vehicle speeds below a threshold.

[0048] Fig.4 is a flowchart generally illustrating a method 400 for compensating for estimated rack force offset according to 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 method 400, such as one or more of the processors of the systems described herein (e.g., a computing device or processor of a vehicle configured to implement offset compensation module 232 and / or other components of RWA controller 200, HWA controller 204, etc.).

[0049] At 404, method 400 includes determining whether one or more enabling conditions for learning the LT and ST offset factors are met, as described herein. If so, method 400 proceeds to 408. If not, method 400 may repeat the determination made in 404 until the one or more enabling conditions are met.

[0050] At 408, method 400 includes learning the LT and ST offset factors, as described herein. For example, offset compensation module 232 applies filtering or other processing techniques to separately isolate and identify LT and ST offsets (e.g., using appropriate filter modules).

[0051] At 412, method 400 includes determining LT and offset compensation values ​​based on the LT and ST offset factors. At 416, method 400 includes applying the LT and ST compensation values ​​to the estimated rack force. For example, the LT and ST compensation values ​​are combined (e.g., summed) to obtain a compensated estimated rack force offset, which is then subtracted from (or added to) the estimated rack force to obtain a compensated estimated rack force.

[0052] At 420, one or more vehicle functions are controlled based on the compensated estimated rack force. For example, the compensated estimated rack force is used to control at least one function of a steering system, such as controlling a motor or motor actuator torque, as described herein.

[0053] The above is intended to illustrate the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully understood. It is intended that the following claims be interpreted to encompass all such variations and modifications.

[0054] The word "example" is used herein to serve 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 illustrate concepts in a concrete manner. As used in this application, the term "or" is intended to mean an inclusive "or" and not an exclusive "or." That is, unless otherwise stated or clear from the context, "X includes A or B" means 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 in each of the foregoing cases.Furthermore, as used in this application and the appended claims, the articles "a / an / an" are generally intended to mean "one or more" unless otherwise indicated or the context clearly indicates a singular form. Furthermore, the use of the term "an implementation" or "an implementation" is not synonymous with the same embodiment or implementation unless described as such.

[0055] As used herein, the terms "a," "an," and "the" refer to both the singular and plural, unless the context clearly indicates otherwise. For example, "a processor" programmed to perform various functions refers to one processor programmed to perform each function individually, or to more than one processor programmed together to perform each of the various functions.

[0056] The systems, algorithms, methods, instructions, etc., described herein may be implemented in hardware, software, or any combination thereof. The 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" is to be understood to include any of the foregoing hardware, either individually or in combination. The terms "signal" and "data" are used interchangeably.

[0057] As used herein, the term module can include a packaged functional hardware unit designed for use with other components, a set of instructions executable by a control device (e.g., a processor executing software or firmware), processing circuitry configured to perform a specific function, and a self-contained hardware or software component that interfaces with a larger system. For example, a module can include an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a circuit, a digital logic circuit, an analog circuit, a combination of discrete circuits, gates, and other types of hardware, or a combination thereof.In other embodiments, a module may include memory storing instructions that can be executed by a controller to implement a feature of the module.

[0058] In one aspect, the systems described herein may be implemented, for example, with a general-purpose computer or a general-purpose processor having a computer program that, when executed, performs the respective methods, algorithms, and / or instructions described herein. Additionally or alternatively, for example, a special-purpose computer / processor may be used, which may include other hardware for executing the methods, algorithms, or instructions described herein.

[0059] Furthermore, all or part of the implementations of the present disclosure may take the form of a computer program product, accessible, for example, from a computer-usable or computer-readable medium. A computer-usable or computer-readable medium may be any device that can, for example, tangibly contain, store, transmit, or transport the program for use by or in connection with any processor. The medium may be, for example, an electronic, magnetic, optical, electromagnetic, or semiconductor device. Other suitable media are also available.

[0060] The above-described embodiments, implementations, and aspects have been described to facilitate a simple understanding of the present invention and do not limit the present invention. On the contrary, the invention is intended to cover various modifications and equivalent arrangements that fall within the scope of the appended claims, which scope should be interpreted as broadly as possible to encompass all such modifications and equivalent structures permitted by law.

Claims

[1] A method for controlling a steering system of a vehicle (10), the method comprising: Obtaining a variety of values ​​corresponding to the operation of the steering system; determining an estimated rack force based on the plurality of values; separately determining (408) a long-term (LT) estimated rack force offset factor and a short-term (ST) estimated rack force offset factor; determining (412) a total compensation value based on a combination of the LT offset factor and the ST offset factor; Applying (416) the total compensation value to the estimated rack force to obtain a compensated estimated rack force; and Controlling (420) at least one function of the steering system using the compensated estimated rack force. [2] Method according to claim 1, characterized bythat the method further comprises determining the estimated rack force based on a rack position reference. [3] Method according to claim 2, characterized by that the method further comprises determining the estimated rack force based on a difference between the rack position reference and an actual rack position. [4] Method according to claim 1, characterized by that the method further comprises controlling (420) a handwheel motor torque based on the compensated estimated rack force. [5] Method according to claim 1, characterized by that determining (408) the LT offset factor and the ST offset factor comprises applying filtering to the estimated rack force. [6] Method according to claim 5, characterized bythat the filtering comprises the use of different low-pass filters (304, 308) to determine the LT offset factor and the ST offset factor, respectively. [7] Method according to claim 1, characterized by that the method (400) further comprises determining (404) whether one or more release conditions are met, and separately determining (408) the LT offset factor and the ST offset factor in response to determining that the one or more release conditions are met. [8] A system for controlling one or more steering functions of a vehicle, the system comprising: one or more sensors (106) configured to obtain a plurality of values ​​corresponding to the one or more steering functions; and a controller (100, 200, 204) configured to determine an estimated rack force based on the plurality of values, separately determines a long-term (LT) offset factor of the estimated rack force and a short-term (ST) offset factor of the estimated rack force, determines a total compensation value based on a combination of the ST offset factor and the ST offset factor, applies the total compensation value to the estimated rack force to obtain a compensated estimated rack force, and which controls one or more steering functions using the compensated estimated rack force. [9] System according to claim 8, characterized by that the control unit (100, 200) is configured to determine the estimated rack force based on a rack position reference. [10] System according to claim 9, characterized bythat the control unit (100, 200) is configured to determine the estimated rack force based on a difference between the rack position reference and an actual rack position. [11] System according to claim 8, characterized by that the controller (100, 204) is configured to control a handwheel motor torque based on the compensated estimated rack force. [12] System according to claim 8, characterized by that the determination (408) of the LT offset factor and the ST offset factor comprises the application of filtering to the estimated rack force. [13] System according to claim 12, characterized by that the filtering comprises the use of different low-pass filters (304, 308) to determine the LT offset factor and the ST offset factor, respectively. [14] System according to claim 8, characterized byin that the control unit (100, 204) is configured to determine whether one or more enabling conditions are met and, in response to determining that the one or more enabling conditions are met, to determine the LT offset factor and the ST offset factor separately. [15] A processing device configured to execute instructions stored in a memory (104) to control one or more steering functions of a vehicle (10), the instructions comprising: Obtaining a plurality of values ​​corresponding to the one or more steering functions; determining an estimated rack force based on the plurality of values; separately determining (408) a long-term (LT) estimated rack force offset factor and a short-term (ST) estimated rack force offset factor; determining (412) a total compensation value based on a combination of the ST offset factor and the ST offset factor; Applying (416) the total compensation value to the estimated rack force to obtain a compensated estimated rack force; and Controlling (420) the one or more steering functions using the compensated estimated rack force. [16] Processing device according to claim 15, characterized by that the instructions include determining the estimated rack force based on a rack position reference. [17] Processing device according to claim 16, characterized by that the instructions include determining the estimated rack force based on a difference between the rack position reference and an actual rack position. [18] Processing device according to claim 15, characterized bythat the instructions include controlling (420) the handwheel motor torque based on the compensated estimated rack force. [19] Processing device according to claim 15, characterized by that determining (412) the LT offset factor and the ST offset factor comprises applying filtering to the estimated rack force, and wherein the filtering comprises using different low-pass filters (304, 308) to determine the LT offset factor and the ST offset factor, respectively. [20] Processing device according to claim 15, characterized by that the instructions include determining (404) whether one or more release conditions are met and separately determining (408) the LT offset factor and the ST offset factor in response to determining that the one or more release conditions are met.

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