ANTI-PUMP-SLIP ALGORITHM FOR HYDRAULIC STEERING SYSTEM

Abstract

A steering system for a vehicle includes a hydraulic steering system configured to, in response to a steering input provided at a steering mechanism of the vehicle, control a pump to control a steering device to steer the vehicle, a sensor configured to sense an angle or position associated with the steering input provided at the steering mechanism, an electric power steering system configured to receive a signal from the sensor and provide powered steering assistance to the hydraulic steering system based on the signal and a pump-slip offset associated with the pump, and a controller configured to determine the pump-slip offset. The pump-slip offset corresponds to a difference between the angle or position associated with the steering input and an actual position of the steering device achieved by the pump.

Claims

1. A steering system for a vehicle, comprising: a hydraulic steering system configured to, in response to a steering input provided at a steering mechanism of the vehicle, control a pump to control a steering device to steer the vehicle; a sensor configured to sense an angle or position associated with the steering input provided at the steering mechanism; an electric power steering system configured to receive a signal from the sensor and provide powered steering assistance to the hydraulic steering system based on the signal and a pump-slip offset associated with the pump; and a controller configured to determine the pump-slip offset, wherein the pump-slip offset corresponds to a difference between the angle or position associated with the steering input and an actual position of the steering device achieved by the pump.

2. The steering system of claim 1, wherein the vehicle is a marine vessel and the steering device is a rudder.

3. The steering system of claim 1, wherein the vehicle is a road vehicle and the steering device is associated with roadwheels of the vehicle.

4. The steering system of claim 1, wherein the controller is configured to determine the pump-slip based on a slip gain factor.

5. The steering system of claim 4, wherein the controller is configured to calculate the slip gain factor based on vehicle speed and a torque associated with the steering mechanism.

6. The steering system of claim 4, wherein the controller is configured to determine the pump-slip further based on a vehicle direction.

7. The steering system of claim 4, wherein the controller is configured to determine the pump-slip in accordance with Slip.sub.i=Slip.sub.i-1(Slip.sub.i-1*[1Slip_Gain])+(HwAg*Slip_Gain), and wherein Slip.sub.i is a current pump-slip value, Slip.sub.i-1 is a previous previously calculated pump-slip value, Slip_Gain is the slip gain factor, and HwAg is a handwheel angle sensor measurement.

8. The steering system of claim 1, wherein the controller is configured to calculate the pump-slip further based on a vehicle direction.

9. The steering system of claim 8, wherein the controller is configured to calculate the pump-slip based on a determination that the vehicle direction is within a predetermined range for a predetermined amount of time.

10. A method for operating a steering system of a vehicle, comprising: using a hydraulic steering system, controlling, in response to a steering input provided at a steering mechanism of the vehicle, a pump to control a steering device to steer the vehicle; sensing, at a sensor, an angle or position associated with the steering input provided at the steering mechanism; receiving, at an electric power steering system, a signal from the sensor and providing powered steering assistance to the hydraulic steering system based on the signal and a pump-slip offset associated with the pump; and determining the pump-slip offset, wherein the pump-slip offset corresponds to a difference between the angle or position associated with the steering input and an actual position of the steering device achieved by the pump.

11. The method of claim 10, wherein the vehicle is a marine vessel and the steering device is a rudder.

12. The method of claim 10, wherein the vehicle is a road vehicle and the steering device is associated with roadwheels of the vehicle.

13. The method of claim 10, further comprising determining the pump-slip based on a slip gain factor.

14. The steering system of claim 13, further comprising calculating the slip gain factor based on vehicle speed and a torque associated with the steering mechanism.

15. The steering system of claim 13, further comprising determining the pump-slip further based on a vehicle direction.

16. The steering system of claim 13, further comprising determining the pump-slip in accordance with Slip.sub.i=Slip.sub.i-1(Slip.sub.i-1*[1Slip_Gain])+(HwAg*Slip_Gain), and wherein Slip.sub.i is a current pump-slip value, Slip.sub.i-1 is a previous previously calculated pump-slip value, Slip_Gain is the slip gain factor, and HwAg is a handwheel angle sensor measurement.

17. The steering system of claim 10, further comprising calculating the pump-slip further based on a vehicle direction.

18. The method of claim 17, further comprising calculating the pump-slip based on a determination that the vehicle direction is within a predetermined range for a predetermined amount of time.

19. A processing device configured to execute one or more instructions stored in memory, wherein executing the one or more instructions causes the processing device to: control a hydraulic steering system configured to, in response to a steering input provided at a handwheel of a vehicle, control a pump to control a steering device to steer the vehicle; receive, from a sensor, an angle or position associated with the steering input provided at the handwheel; control an electric power steering system to receive a signal from the sensor and provide powered steering assistance to the hydraulic steering system based on the signal and a pump-slip offset associated with the pump; and determine the pump-slip offset, wherein the pump-slip offset corresponds to a difference between the angle or position associated with the steering input and an actual position of the steering device achieved by the pump.

20. The processing device of claim 19, wherein the vehicle is a marine vessel and the steering device is a rudder.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity.

[0008] FIG. 1 is a schematic illustration of a steering system for a marine vessel according to the principles of the present disclosure;

[0009] FIG. 2 is a schematic illustration of an electric power steering system for the marine vessel according to the principles of the present disclosure;

[0010] FIG. 3 is another schematic illustration of the electric power steering system for the marine vessel according to the principles of the present disclosure;

[0011] FIG. 4 generally illustrates a controller according to the principles of the present disclosure;

[0012] FIG. 5A generally illustrates an anti-pump-slip algorithm according to the principles of the present disclosure.

[0013] FIG. 5B generally illustrates a long-term center-learn algorithm according to the principles of the present disclosure.

[0014] FIG. 6 generally illustrates steps of an example method for compensating for pump-slip according to the principles of the present disclosure.

DETAILED DESCRIPTION

[0015] The following discussion is directed to various embodiments of the disclosure. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. In addition, one skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment.

[0016] A vehicle, such as a car, truck, sport utility vehicle, crossover, mini-van, marine craft or vessel, aircraft, all-terrain vehicle, recreational vehicle, or other suitable forms of transportation, typically includes a steering system, such as an electronic power steering (EPS) system, a steer-by-wire (SbW) steering system, a hydraulic steering system, or other suitable steering system. The steering system of such a vehicle typically controls various aspects of vehicle steering including providing steering assist to an operator of the vehicle, controlling steerable wheels of the vehicle, and the like.

[0017] A marine vessel may implement marine inboard or inboard/outboard drive steering having hydraulic power assist to provide a more comfortable and efficient steering experience for an operator of a marine craft. For example, a hydraulic cylinder may be attached to a lower unit or rudder steering link at a transom and pressurized fluid is supplied from a pump (e.g., a steering pump) associated with an engine of the marine vessel. At a helm of the vessel, a mechanical rotary push-pull cable steering system is coupled to a cable that is routed to the transom and attached to the same steering link as the lower unit. The cable passes through a shuttle valve on the hydraulic cylinder. As a load in the cable increases (i.e., turning the wheel which pushes or pulls the cable), the valve actuates and allows fluid to enter the cylinder, thereby pushing or pulling the rudder/lower unit to steer the vessel. In the event of a failure in the hydraulic system, the operator can still steer the vessel (without power assist) via the mechanical cable connection.

[0018] In some examples, a marine vessel (or other vehicles with a steering system that uses a hydraulic steering pump) may include an EPS system. As one example, a column EPS system is mounted or coupled between a handwheel of the marine vessel (e.g., proximate the helm) and the steering pump. The EPS provides powered assist/assistance for hydraulic steering. However, issues such as hydraulic pump-slip can cause the handwheel position to shift independently of end user (e.g., driver/pilot) steering (i.e., without the end user rotating the handwheel). For example, pump-slip may refer to a difference between an expected or optimal flow rate of a hydraulic pump and the actual flow rate delivered by the pump, which may result in a difference between a commanded steering or rudder position (e.g., as input to the handwheel by the user) and an actual rudder position achieved by the hydraulic steering system. Accordingly, a handwheel angle (HwAg) sensor reading from an EPS sensor may not be consistent with a driving angle and position-based EPS features may be disabled. To compensate for or correct differences between the sensed handwheel position and the driving angle and continue to use position-based EPS features, marine vessels that use hydraulic steering may further require one or more additional angle sensors (e.g., an angle sensor arranged on an outboard engine) to derive the handwheel angle/position.

[0019] Marine vessel and other EPS systems and methods according to the present disclosure are configured to implement anti-pump-slip techniques (e.g., an anti-pump-slip algorithm) to compensate for pump-slip offset. For example, pump-slip can be considered as a very slow movement relative to steering performed by the end user. Accordingly, a long-term center learn algorithm may be used to only retain an angle offset caused by pump-slip and correct a final angle output. In other words, the algorithm learns and compensates for the amount of pump-slip. Since response rate is a tunable, vehicle speed dependent variable, the response rate can be adjusted based on dynamics of the vessel. An error between a calculated and a real/actual pump-slip offset is sufficiently small for relative position-based features, such as navigation and heading hold features. In this manner, anti-pump-slip techniques according to the principles of the present disclosure enable navigation, heading hold, and/or other EPS features without additional sensors and associated costs.

[0020] Accordingly, in contrast to hydraulic steering marine vessels or other vehicles that need angle sensors (e.g., angle sensors mounted on an outboard engine) to measure steering device angles to enable position-based EPS features, the anti-pump-slip techniques of the present disclosure do not require external angle position sensors to enable navigation, heading hold, or other features.

[0021] Although described with respect to pump-slip, the principles of the present disclosure further relate to slip associated with other fluid/hydraulic components, such as various pumps, valves, cylinder seals, etc. Accordingly, techniques for compensating for pump-slip as described herein are further configured to compensate for slip caused by other components in a hydraulic, pump-bases steering system.

[0022] Further, although described with respect to marine vessels, the principles of the present disclosure may be implemented for other types (e.g., non-marine) of vehicles. For example, references to various components of a marine vessel may correspond to analogous components of non-marine steering systems (e.g., a rudder may more generally correspond to a steering component of a steering system, such as roadwheels, a steering rack, or other component configured to control roadwheels of a vehicle in response to driver input). As used herein, the term steering device may more generally refer to a rudder, roadwheels, or other steering system component configured to control the steering direction of a marine vessel, vehicle, etc.

[0023] FIG. 1 generally illustrates a steering system 10 according to the principles of the present disclosure. While the steering system 10 is shown disposed in a marine vessel 11, the principles of the present disclosure can be implemented in other (i.e., non-marine) types of vehicles. Example steering systems for marine vessels are described in more detail in U.S. Pat. No. 11,230,360, issued on Jan. 25, 2022, and U.S. Patent Pub. No. 2021/0284314, filed on Mar. 10, 2021, the entire disclosures of which are incorporated herein by reference. The marine vessel 11 may include any suitable marine vessel that requires manual steering. As will be appreciated from the disclosure herein, the steering system 10 includes an electric power assist system for lowering the required manual effort required by an operator of the marine vessel 11.

[0024] The steering system 10 includes a steering mechanism or handwheel 12. The handwheel 12 may be disposed on a helm of the marine vessel 11 or some other suitable location. The operator of marine vessel 11 engages the handwheel 12 in order to control steering of the marine vessel 11. The steering system 10 includes a propulsion mechanism that includes a motor 14 and a steering device, such as a rudder 16. While only the motor 14 and the rudder 16 are described herein, it should be understood that the propulsion mechanism may include additional or fewer components than described herein. For example, the propulsion mechanism may include one or more motors, a propulsion engine, one or more rudders, one or more propellers, other suitable components, or a combination thereof.

[0025] The motor 14 may include any suitable motor, such as an outboard motor, an inboard motor, and the like. The operator of the marine vessel 11 may engage a throttle (not shown) disposed proximate the handwheel 12 to engage and/or control the motor 14. For example, the operator may increase or decrease a rotational velocity of a propeller associated with the motor 14 by moving the throttle. Additionally, or alternatively, the operator may raise or lower the propeller of the motor 14 using one or more switches disposed on the throttle or proximate the throttle.

[0026] In the illustrated embodiments, the handwheel 12 may be in direct communication with the rudder 16. For example, the system 10 may include a mechanism that connects the handwheel 12 to the rudder 16. For example, the mechanism coupling the handwheel 12 to the rudder 16 is a push/pull cable 18 in some embodiments. As the operator turns the handwheel 12, the cable 18 translates the rotation movement of the handwheel 12, which causes the rudder 16 to move in a first direction or a second direction, opposite the first direction (FIG. 2).

[0027] Referring now to FIG. 2, an electric power steering (EPS) system 20 that is part of the overall steering system 10 is illustrated. The EPS system 20 interacts with the cable 18 and the rudder 16 to provide assistance to the steering effort of the marine vessel operator. As described above, the cable 18 is in operative communication with the handwheel 12 proximate a first end of the cable 18 at the helm of the marine vessel 11 and in operative communication with the rudder 16 proximate a second end of the cable 18. While contemplated that a direct connection between the cable 18 and the rudder 16 is possible, as shown in the illustrated embodiment a link member 22 may couple the cable 18 to the rudder 16. In such an embodiment, the link member 22 is pivotable about an axis upon translation of the cable 18 due to steering inputs at the handwheel 12. The link member 22 is operatively coupled to the rudder 16 to convert the translational push/pull motion of the cable 18 to rotary motion, thereby facilitating steering movement of the rudder 16.

[0028] The EPS system 20 includes a linear force sensor 24 that is positioned on the cable 18 between the first and second ends of the cable 18. The linear force sensor 24 is in operative communication (i.e., wired or wireless) with a controller 26 in a manner that communicates a signal detected by the linear force sensor 24 to the controller 26. The controller 26 may include any suitable controller or processor, such as those described herein. The controller 26 may be configured to executed instructions stored on a memory. The memory may comprise a single disk or a plurality of disks (e.g., hard drives), and includes a storage management module that manages one or more partitions within the memory. In some embodiments, memory may include flash memory, semiconductor (solid state) memory or the like. The memory may include Random Access Memory (RAM), a Read-Only Memory (ROM), or a combination thereof.

[0029] The controller 26 receives the signal from the linear force sensor 24 to determine a force input of the cable 18 that is indicative of the steering input at the handwheel 12. Although detection of the steering input at the handwheel 12 is illustrated and described herein as being performed with the linear force sensor 24, it is to be appreciated that such detection may be made in other embodiments with a torque sensor at the helm of the marine vessel and which is operatively coupled to the handwheel 12 or an associated rotatable component.

[0030] The controller 26 is also in operative communication with an electric motor 28 of the EPS system 20. The electric motor 28 includes an output shaft that drives a gear arrangement 30 within a gearbox. An output of the gear arrangement 30 is operatively coupled to a pinion 32 that is in teeth meshed engagement with a rack 34. The rack 34 is operatively coupled to the cable 18. The rack 34 is positioned closer to the link member 22 than the proximity of the linear force sensor 24 (or torque sensor) to the link member 22. The link member 22 may be part of a multi-component linkage mechanism that the rack 34 is directly coupled to in some embodiments.

[0031] In operation, the linear force sensor 24 communicates the load to the controller 26, which then applies an appropriate assist with the electric motor 28 and the driven rack 34. The powered movement of the rack 34 rotates the link member 22 to ultimately steer the marine vessel via the rudder 16.

[0032] Referring now to FIG. 3, another aspect of an EPS system is illustrated and referred to generally with numeral 120. In this example, the EPS system 120 does not require a rack and pinion. The EPS system 120 of FIG. 3 may operate similarly to the EPS system 20 of FIG. 2, but instead of a rack may use a rotary-type gearbox 122 (e.g., worm, pinion, etc.) connected directly to the rudder shaft to multiply torque from an electric motor to the shaft. The push-pull cable 18 is connected directly to the rudder arm 124. At the connection point a force sensor 126 is installed. A controller may monitor force in the cable through the force sensor 126 (and therefore load/torque experienced by operator) and supply energy to the motor and gearbox 122 to assist in steering the vessel. If a position sensor is installed at the helm (steering position) and the rudder (rudder angle) then the cable 18 may be removed to offer a true steer-by-wire operation.

[0033] A steering system, such as the steering system 10, implementing an EPS system (e.g., either of the EPS systems 20 and 120 described herein or other example EPS systems) may be configured to implement anti-pump-slip techniques (e.g., an anti-pump-slip algorithm) according to the principles of the present disclosure. For example, the steering system 10 may include one or more controllers configured to implement the techniques of the present disclosure, such as a controller 400 as shown in FIG. 4. The controller 400 may include any suitable controller, such as an electronic control unit or other suitable controller. The controller 400 may be configured to control, for example, the various functions of the steering system and/or various functions of a marine vessel. The controller 400 may include a processor 402 and a memory 404. The processor 402 may include any suitable processor, such as those described herein. Additionally, or alternatively, the controller 400 may include any suitable number of processors, in addition to or other than the processor 402. The memory 404 may comprise a single disk or a plurality of disks (e.g., hard drives), and includes a storage management module that manages one or more partitions within the memory 404. In some embodiments, memory 404 may include flash memory, semiconductor (solid state) memory or the like. The memory 404 may include Random Access Memory (RAM), a Read-Only Memory (ROM), or a combination thereof. The memory 404 may include instructions that, when executed by the processor 402, cause the processor 402 to, at least, control various aspects of the steering system and marine vessel. Additionally, or alternatively, the memory 404 may include instructions that, when executed by the processor 402, cause the processor 402 to perform functions associated with the systems and methods described herein.

[0034] The controller 400 may receive one or more signals from various measurement devices or sensors 406 indicating sensed or measured characteristics of the steering system, the marine vessel, etc. The sensors 406 may include any suitable sensors, measurement devices, and/or other suitable mechanisms. For example, the sensors 406 may include one or more torque sensors or devices, one or more handwheel position sensors or devices, one or more motor position sensor 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 a handwheel torque, a handwheel angle, vehicle speed, other suitable information, and/or a combinations thereof.

[0035] In some embodiments, the controller 400 may perform the methods described herein. However, the methods described herein as performed by the controller 400 are not meant to be limiting, and any type of software executed on a controller or processor can perform the methods described herein without departing from the scope of this disclosure. For example, a controller, such as a processor executing software within a computing device, can perform the methods described herein.

[0036] FIG. 5A is an example anti-pump-slip algorithm or process 500 according to the principles of the present disclosure. For example, one or more computing devices, processors, controllers, etc., such as the controller 400, may be configured to implement/execute functions of the algorithm 500. For example, the memory 404 may store instructions, executable by the processor 402, corresponding to functions/steps of the algorithm 500.

[0037] For example, a handwheel angle sensor reading/calculation is responsive to (e.g. indicative of) both user steering input, such as user input at the handwheel as shown at 504, and pump-slip offset as shown at 508. In other words, a handwheel angle sensor and/or other position measurement/reading is affected by both actual user input and the pump-slip offset. Further, the handwheel angle sensor measurement may not accurately indicate user input alone and also includes an error/offset component caused by pump-slip. The handwheel angle sensor reading (i.e., an output or output signal of the handwheel angle sensor responsive to both the user steering input 504 and the pump-slip offset 508) is shown schematically at 512.

[0038] The handwheel angle sensor measurement 512 is provided to an anti-pump-slip algorithm (e.g., a long-term, center learn algorithm) 516. The algorithm 516 is configured to learn a center position of the steering system, such as a center position of the rudder, and a position (e.g., handwheel angle) of the handwheel when the rudder is in the center position. The anti-pump-slip algorithm 516 may receive inputs including, but not limited to, the handwheel angle sensor measurement/reading 512, a tunable response rate 520, and one or more other inputs indicative of steering/movement of the vessel (e.g., heading or trajectory information). In this manner, the anti-pump-slip algorithm 516 is configured to determine and store a learned pump-slip offset value 524 (which may remain fixed/static or may change over time). With the pump-slip offset known (as represented by the learned/stored pump-slip offset value 524, EPS system features and control can be used by the steering system by compensating for the known pump-slip offset.

[0039] FIG. 5B shows an example implementation of the long-term center-learn algorithm 516 according to the principles of the present disclosure. A slip gain factor is calculated based on handwheel torque (e.g., corresponding to the user steering input 504 shown in FIG. 5A) and vehicle speed. The slip gain factor is used to calculate long-term slip.

[0040] For example, the handwheel torque and the vehicle speed are provided to a slip gain factor calculator 528 configured to obtain the slip gain factor based on the handwheel torque and the vehicle speed. As one example, the slip gain factor calculator obtains the slip gain factor based on a calibration table (e.g., a 3D calibration table, lookup table, etc.) that correlates the vehicle speed and the handwheel torque to the slip gain factor (e.g., to output, based on the vehicle speed and the handwheel torque, a slip gain factor selected from a plurality of slip gain factors). In an example, the calculator 528 may provide the slip gain factor based on a plurality of slip gain curves for respective vehicle speeds or ranges. For example, for a given vehicle speed or speed range, the slip gain factor may decrease as handwheel torque increases. Example slip gain factor curves/values for different vehicle speeds are shown at 530.

[0041] In this manner, gain can be scaled based on vehicle speed and/or handwheel torque. As one example, gain can be provided/increased when no handwheel torque is present/input by the driver at predetermined vehicle speeds (e.g., vehicle speeds above a threshold). Conversely, gain can be decreased or stopped (i.e., not applied) when handwheel torque is present.

[0042] A long-term slip calculator 532 calculates the long term slip based on the slip gain factor and the handwheel angle sensor measurement. As one example, the long-term slip (which may correspond to a handwheel position, an offset from a center handwheel position, etc.) may be calculated/updated in accordance with:

[00001]$\begin{array}{cc}& \left(\mathrm{Equation}1\right)\end{array}$$\begin{array}{cc}{\mathrm{Slip}}_i={\mathrm{Slip}}_{i-1}-\left({\mathrm{Slip}}_{i-l}*\left[1-\mathrm{Slip\_Gain}\right]\right)+\left(\mathrm{HwAg}*\mathrm{Slip\_Gain}\right),& \end{array}$

[0043] where Slip.sub.i is a current/updated long-term slip, Slip.sub.i-1 is a previous (e.g., previously calculated/accumulated long-term slip), Slip_Gain is the slip gain factor, and HwAg is the handwheel angle sensor measurement.

[0044] In examples where vehicle heading/direction are available (e.g., based on GPS or other navigation system data), vehicle direction can be used to calculate, adjust, reset, etc. the long term slip, an offset applied to the handwheel angle sensor measurement, and do on. For example, the process 500 may receive data or a signal indicating vehicle direction (e.g., vehicle direction data obtained by GPS circuitry) and determine whether vehicle direction (e.g., heading or bearing) is within a predetermined range for a predetermined amount of time. The predetermined range may correspond to a predetermined value range of a straight-ahead or center bearing. For example, the vehicle direction being within the predetermined range may indicate that the driver is intending to travel straight ahead. Accordingly, the handwheel position/angle being maintained to maintain the straight-ahead bearing can be assumed to correspond to the slip amount. As such, the current handwheel angle sensor measurement can be used as the long-term slip (e.g., a current long-term slip value (an angle or angle offset) can be replaced with a value corresponding to the current handwheel angle sensor measurement.

[0045] FIG. 6 generally illustrates steps of an example method 600 for compensating for pump-slip according to the principles of the present disclosure. Steps of the method 600 may be performed by a system, one or more processors or processing devices, controllers, computing devices, etc. as described herein (e.g., the controller 400).

[0046] At 604, the method 600 includes receiving one or more vehicle signals. The vehicle signals may be received from respective sensors, calculated, estimated, or otherwise obtained. The vehicle signals may include, but are not limited to, a handwheel angle sensor measurement, vehicle speed, handwheel torque, etc.

[0047] At 608, the method 600 may include selectively resetting long-term slip based on the handwheel angle sensor measurement. For example, as described above, the long-term slip may be set to a current handwheel angle sensor measurement in response to a determination that the vehicle direction/bearing is within a predetermined range for a predetermined amount of time (e.g., 10 seconds).

[0048] At 612, the method 600 may include calculating a slip gain factor. For example, calculating the slip gain factor may including calculating the slip gain factor based on the vehicle speed and the handwheel torque (e.g., using a lookup table as described above).

[0049] At 616, the method 600 may include calculating long-term slip (e.g., a long-term slip handwheel position) based on the slip gain factor and the handwheel angle sensor measurement (e.g., in accordance with Equation 1).

[0050] At 620, the method 600 may include generating a compensated handwheel angle sensor value based on the long-term slip. For example, the compensated handwheel angle sensor value may correspond to an offset angle relative to the handwheel angle sensor measurement. Since the compensated handwheel angle sensor value is based on the pump-slip, the compensated handwheel angle sensor value compensates for any pump-slip resulting in a difference between the handwheel torque provided by the driver (and, accordingly, the handwheel position/angle) and the position of the rudder or other steering device.

[0051] At 624, the method 600 may include, in some examples, controlling the handwheel based on the compensated handwheel angle sensor value (e.g., to perform heading hold functions).

[0052] The above discussion is meant to be illustrative of 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 appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.

[0053] The word example is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as example is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word 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 specified otherwise, or clear from 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. In addition, the articles a and an as used in this application and the appended claims should generally be construed to mean one or more unless specified otherwise or clear from context to be directed to a singular form. Moreover, use of the term an implementation or one implementation throughout is not intended to mean the same embodiment or implementation unless described as such.

[0054] Implementations the systems, algorithms, methods, instructions, etc., described herein can be realized in hardware, software, or any combination thereof. The hardware can 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 circuit. In the claims, the term processor should be understood as encompassing any of the foregoing hardware, either singly or in combination. The terms signal and data are used interchangeably.

[0055] 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 controller (e.g., a processor executing software or firmware), processing circuitry configured to perform a particular 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, digital logic circuit, an analog circuit, a combination of discrete circuits, gates, and other types of hardware or combination thereof. In other embodiments, a module can include memory that stores instructions executable by a controller to implement a feature of the module.

[0056] Further, in one aspect, for example, systems described herein can be implemented using a general-purpose computer or general-purpose processor with a computer program that, when executed, carries out any of the respective methods, algorithms, and/or instructions described herein. In addition, or alternatively, for example, a special purpose computer/processor can be utilized which can contain other hardware for carrying out any of the methods, algorithms, or instructions described herein.

[0057] Further, all or a portion of implementations of the present disclosure can take the form of a computer program product accessible from, for example, a computer-usable or computer-readable medium. A computer-usable or computer-readable medium can be any device that can, for example, tangibly contain, store, communicate, or transport the program for use by or in connection with any processor. The medium can be, for example, an electronic, magnetic, optical, electromagnetic, or a semiconductor device. Other suitable mediums are also available.

[0058] The above-described embodiments, implementations, and aspects have been described in order to allow easy 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 included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structure as is permitted under the law.