Hybrid steering system and method implementing virtual and mechanical stops

A steering system and method can determine one or more position-related characteristics of a steering column of a machine, determine that the one or more position-related characteristics indicate that a resistive force is to be applied to the steering column, and control operation of an electric motor to apply the resistive force to the steering column, wherein a mechanical stop (e.g., a progressive mechanical stop) can be provided to restrict rotation of the steering column. One or more virtual stops may be set to limit rotation of the steering column by way of controlling the operation of the electric motor to apply the resistive force.

TECHNICAL FIELD

The present disclosure relates to electronic or steer-by-wire steering, and more particularly to electronic or steer-by-wire steering systems and methods that provide or implement at least one virtual stop and mechanical stop pairing.

BACKGROUND

Conventional electronic steering may use a position sensor to detect rotational position of a steering wheel of a machine. Steering wheel rotation can cause the position sensor to output a position signal to an actuating device (e.g., a microprocessor that controls a hydraulic pump), which can then cause the wheels of the machine to rotate in correspondence with the steering wheel rotation.

A mechanical stop may be coupled to a steering column of the steering wheel to prevent movement beyond a particular angle from the “straight ahead” or “zero-angle” position of the steering wheel. However, metal-to-metal contact between the mechanical stop and the steering column can occur, which may result in undesirable sound and/or tactile feedback to the operator. A compliant member can be provided for the mechanical stop but may limit or consume an excess amount of angular rotation for the steering wheel, which is particularly undesirable in the context of steering wheels already limited in rotational range to three hundred sixty degrees or less.

U.S. Pat. No. 6,389,343 (“the '343 patent”) describes an apparatus and methods for controlling the resistance to the movement of a steering shaft that is operable to move as a function of an operator input. A position sensor is coupled with the steering shaft and transmits a shaft position signal as a function of the position of the steering shaft, and a processing device is coupled with the position sensor to receive the shaft position signal and transmit a resistance signal as a function of the shaft position signal. A resistance device is coupled with the steering shaft and with the processing device to receive the resistance signal. According to the '343 patent, the resistance device resists the movement of the steering shaft as a function of the resistance signal.

SUMMARY OF THE DISCLOSURE

In one aspect, the present disclosure implements a steering method. The steering method can comprise receiving, using a processor, position signals associated with rotational position of a steering column, the steering column having a mechanical stop operatively provided to mechanically limit rotation of the steering column to a first range of rotation; determining, using the processor, at least one position-related characteristic of the steering column based on the received position signals; determining, using the processor, that the determined at least one position-related characteristic indicates that a resistive force is to be applied to the steering column; and controlling, using the processor, operation of an electric motor to apply the resistive force to the steering column responsive to said determining that the determined at least one position-related characteristic indicates that the resistive force is to be applied to the steering column.

In another aspect, the present disclosure implements or provides a non-transitory computer-readable storage medium storing computer-readable instructions that, when executed by a computer, cause the computer to perform a steering method. The steering method can comprise determining a plurality of position-related characteristics of a steering column of a working machine, the plurality of position-related characteristics including rotational positioning of the steering column and rotation speed of the steering column; dynamically setting a virtual stop to limit rotation of the steering column based on said determining the plurality of position-related characteristics of the steering column, the steering column having a progressive mechanical stop operatively provided to mechanically limit rotation of the steering column past the virtual stop; and implementing the dynamically set virtual stop by applying a resistive force to the steering column via control of an electric motor when the steering column is at a position within an operational range of the progressive mechanical stop.

In yet another aspect a steering system for a working machine can be provided or implemented. The steering system can comprise a control interface to receive an input to control steering of the working machine; a steering column operatively coupled to the control interface and a steering assembly to control steering of the working machine based on the input; a progressive mechanical stop operatively coupled to the steering column to mechanically limit rotation of the steering column to a first range of rotation; an electric motor operatively coupled to the steering column to apply a resistive force to the steering column; at least one position sensor operatively coupled to the steering column to signal rotational position of the steering column; and a controller operatively coupled to the electric motor and the at least one position sensor to output control signals to the electric motor to apply the resistive force to the steering column based on the rotational position of the steering column. The controller, via the control signals to the electric motor, can provide virtual end stops to further limit rotation of the steering column to a second range of rotation within the first range of rotation, and the electric motor can apply the resistive force to the steering column from a state where no resistive force is applied to the steering column responsive to the control signals.

DETAILED DESCRIPTION

The present disclosure relates to electro-hydraulic (EH) steering systems and methods, and more particularly to EH steering systems and methods that provide or implement at least one virtual stop and mechanical stop pairing. EH steering systems may be known or referred to as a steer-by-wire steering systems.

Referring now to the drawings,FIG.1illustrates a side view of a machine100according to embodiments of the disclosed subject matter. The machine100, which may be a work machine, can incorporate an electro-hydraulic steering system as disclosed herein.

The machine100may include an engine housing102, an operator station104, and a work implement106, such as a bucket for digging and loading material. In the example of machine100being a wheel loader, the work implement106can be powered and controlled by a number of actuators, including a tilt actuator108. The machine100may include front and rear ground engaging devices, such as front wheels110and rear wheels112that support the machine100. The engine housing102may include a power source, such as an engine114, that may provide power to the front and/or rear wheels110,112.

To drive the machine100, an operator may manipulate one or more control interfaces (e.g., a steering wheel) that may be housed within the operator station104. The control interface(s) may ultimately steer the machine100by extending and retracting hydraulic steering actuators or cylinders (not shown). In the example of machine100being a wheel loader, the machine100may include a front end116and a back end118. The hydraulic steering actuators may extend between the front and back ends116,118to articulate the front end116relative to the back end118about an articulation axis120. Though the electro-hydraulic steering system is discussed with reference to an articulating work machine, the principles, systems, and methods described herein can be equally applicable to a more conventional electro-hydraulic steering system that turns the wheels relative to the machine body to steer the machine. Thus, embodiments of the disclosed subject matter can involve machines in the form of wheel loaders, trucks, motor graders, etc.

Turning toFIG.2,FIG.2is a functional block diagram of a steering system200according to one or more embodiments of the disclosed subject matter. The steering system200can be implemented in machines according to embodiments of the disclosed subject matter, such as the machine100shown inFIG.1.

The steering system200can include a control interface212, a steering column or shaft214, one or more sensors216, a controller218, and an electric motor220. The steering system200can also include one or more mechanical stops230. The steering column214can be operatively coupled to the control interface212at one end and at an opposite end to a steering assembly, which may include a rack and pinion, tie rod, kingpin, etc. (not shown), to control steering of the machine100. Generally, steering control can be responsive to an input to the control interface212, which can control the steering column214, under control of the controller218.

The control interface212can be a steering input device, such as a steering wheel that moves as a function of an input from an operator of the machine100, for instance. The steering input device, according to embodiments of the disclosed subject matter, is not limited to a steering wheel, and may take the form of a portion of a steering wheel, a steering yoke, a lever, or a graphical user interface (GUI), as non-limiting examples.

The sensor216can be a position sensor and, as such, can be operatively coupled to the steering column214to signal rotational position of the steering column214. The sensor216in the form of a position sensor can be a rotary or linear position sensor, as non-limiting examples. As another example, the sensor216can be an angular or rotational speed sensor that senses angular or rotational speed of the steering column214. As yet another example, the sensor216can be an encoder (or multiple encoders) that determines positioning of the electric motor220, which can be used to determine positioning of the steering column214.

The sensor216can output position signals217corresponding to rotational or angular position of the steering column214to the controller218as a function of the position of the steering column214. As used herein, such position signals217can be true position signals or position-based signals (e.g., speed, acceleration, etc.) depending upon the type of sensor216. As noted above, multiple sensors216can be implemented, where such sensors216can be the same type or different types (e.g., a position sensor and a speed sensor).

The electric motor220, which may be a DC brushless motor as a non-limiting example, can be operatively coupled to the steering column214(e.g., around the steering column214) to apply or provide a resistive force to the steering column214. Application of the resistive force may also be characterized as providing torque feedback. Discussed in more detail below, the electric motor220may receive control signals221from the controller218. Thus, the electric motor220can apply the resistive force to resist rotational movement of the steering column214, for instance, as a function of or responsive to the control signals221from the controller218. That is, when the steering column214receives an input from the control interface212to rotate in a first direction (e.g., clockwise) the electric motor220can apply the resistive force in a second direction opposite the first direction (e.g., counterclockwise) to resist the rotational movement in the first direction. The application of resistive force can be based on the current angular position of the steering column214and, optionally, a speed or velocity associated with the rotation of the steering column214in the first direction.

Each mechanical stop230can be operatively provided relative to the steering column214to constrain rotation of the steering column214, and prevent rotational movement of the steering column214beyond a particular angle. Constraining rotation by the mechanical stop230can mean providing mechanical resistance to the steering column214. The resistance can progressively and/or iteratively increase, for instance, linearly or in levels, until ultimately reaching a high enough resistance value to create a so-called hard mechanical stop past which the steering column214cannot be further rotated. Thus, according to embodiments of the disclosed subject matter, the mechanical stop230can be characterized as a progressive mechanical stop, wherein the mechanical stop230is activated by or engaged with the steering column214and provides an opposing resistive force (e.g., counterclockwise) opposing the rotation of the steering column214toward the hard mechanical stop (e.g., clockwise) that is progressively increased until the hard mechanical stop is reached. Likewise, the resistance applied by the progressive mechanical stop can decrease (e.g., progressively) when the steering column214is within the operational range of the progressive stop and the steering column214is rotated away from the hard mechanical stop (e.g., counterclockwise) toward a non-operational range of the progressive stop (i.e., when the mechanical stop230is not activated by or engaged with the steering column214).

Non-limiting examples of mechanical stops230in the form of progressive mechanical stops according to embodiments of the disclosed subject matter include a spring operatively coupled to the steering column214and/or an assembly thereof, a compliant member (e.g., an elastomer covering) provided on the steering column214and/or an assembly thereof, and a friction device that uses friction to generate a resistive force (e.g., restricted in geometry to increase friction). Optionally, the mechanical stop230can be comprised of or consist of two of more mechanical stops230, such as two or more of the foregoing exemplary progressive mechanical stops. Moreover, one or more mechanical stops230may be provided at and define a limit to a range of rotation for the steering column214.

The controller218can be operatively coupled to the electric motor220and the sensor216. The controller218can receive position signals217from the sensor216and output the control signals221based on the received position signals217to control the electric motor220. More specifically, the control signals221can be output to the electric motor220based position-related characteristics of the steering column214as sensed by the sensor216at a single instance of time or at multiple instances of time. Additionally or alternatively, the control signals221can be based on angular or rotational speed of the steering column214at a single instance of time or at multiple instances of time. Depending upon the type of sensor216and the corresponding position signals217received by the controller218, the controller218can determine some or all of the position-related characteristics of the steering column214. For instance, in a case where the sensor216signals positioning of the steering column214the controller218may determine rotational speed, rotational acceleration, and/or direction of rotation of the steering column214.

The controller218can use the position-related characteristics of the steering column214to determine whether to control the electric motor220to apply (or not) a resistive force to the steering column214. The controller218can also use the position-related characteristics of the steering column214to determine how much resistive force to have the electric motor220apply to the steering column214and/or when to have the electric motor220apply the resistive force to the steering column214. Thus, the controller218can generate the control signals221based on one or more determined position-related characteristics of the steering column214and further processing thereof.

Control of the electric motor220, via the control signals221, can include selectively operating the electric motor220to apply the resistive force to the steering column214, as noted above. According to one or more embodiments, such control can be from a first state where the electric motor220does not apply any resistive force to the steering column214to a second state where the electric motor220begins applying the resistive force to the steering column214. Optionally, the resistive force applied to the steering column214, once initiated, can increase as the steering column214is moved toward the mechanical stop230. For instance, the controller218can output control signals221to cause the electric motor220to increase the resistance to movement for the steering column214as the rotational speed of the steering column214increases or reaches a predetermined value. As another example, the controller218can output control signals221to cause the electric motor220to increase the resistance to movement for the steering column214as the steering column214approaches or reaches a particular rotational position. Discussed in more detail below, the particular rotational position can be defined by a predetermined or dynamically set virtual stop (e.g., virtual end stop). The increase in resistive force can be linear or non-linear, such as exponential, stepped, or pulsed.

The controller218may be or include processing circuitry or a processor (e.g., a microprocessor), where the processing circuitry or processor can process the position signals217from the sensor216. As noted above, the processing of the position signals217can include determining position-related characteristics of the steering column214, such as rotational speed and/or rotational acceleration.

Optionally, memory219can be implemented. Such memory219can be provided offboard and/or onboard the controller218, such as shown inFIG.2. The memory219can be configured to store, in a lookup table, for instance, one or more virtual stops (e.g., virtual end stops) to selectively control application of the resistive force by the electric motor220. Such virtual stops can be stored in correlation with various position-related characteristics of the steering column214, such as angular or rotational position of the steering column214, angular or rotational position of the steering column214with respect to one or more of the mechanical stops230, rotation speed of the steering column214, rotational acceleration of the steering column214, and/or direction of rotation of the steering column214. The one or more virtual stops can be stored in the memory219in advance or dynamically as part of a learning process, for instance.

FIG.3is a diagrammatic representation showing steering ranges and steering stops according to one or more embodiments of the disclosed subject matter.

In this example, the horizontal line inFIG.3represents rotational position of the steering column214, each star represents a virtual stop320, and each of the dashed boxes represents a progressive mechanical stop330for the mechanical stop230ofFIG.2. Embodiments of the disclosed subject matter, however, are not limited to mechanical stops230in the form of progressive mechanical stops330. Each dot associated with the progressive mechanical stops330represents a hard mechanical stop332of the progressive mechanical stop330past which the steering column214is mechanically prohibited from moving.

Rotation of the steering column214can be limited according to a first range of rotation300. According to one or more embodiments, the first range of rotation300can be less than or equal to three hundred sixty degrees.

The progressive mechanical stops330can limit rotation of the steering column214according to the first range of rotation300. For example, the hard mechanical stops332can define the first range of rotation300for the steering column214, such as shown inFIG.3. That is, the steering column214may be positioned, via the input to the control interface212, anywhere between the hard mechanical stops332but not past either of the hard mechanical stops332. Alternatively, the first range of rotation300for the steering column214can be defined inward of the hard mechanical stops332, such as a position between the hard mechanical stop332and initiation of the progressive mechanical stop330. Incidentally, the operational range of the progressive mechanical stop330can be defined from the hard mechanical stop332to initiation of the progressive mechanical stop330. Optionally, the first range of rotation300may be characterized or defined based on whether or not any virtual stops320are set within the operational range of the progressive mechanical stop330from at or just before the hard mechanical stop332inward to at or just after initiation of the progressive mechanical stop330.

Rotation of the steering column214can also be limited according to a second range of rotation302. The second range of rotation302can be characterized or defined as between corresponding pairs of virtual stops320. For instance, the second range of rotation302can be defined between the virtual stops320(2) inFIG.3. As another example, the virtual stops320(1) can define the second range of rotation302. In the former example, the range of rotation between the virtual stops320(1) may then be characterized as a third range of rotation304. To be clear, thoughFIG.3shows two pairs of virtual stops320(1),320(2), a pair of virtual stops may be comprised of or consist of only the virtual stops320(1), only the virtual stops320(2), only one of the virtual stops320(1), only one of the virtual stops320(2), or virtual stops in addition to virtual stops320(1) and320(2).

Additionally, thoughFIG.3shows virtual stops320(1) outside the operational range of the progressive mechanical stops330and virtual stops320(2) inside the operational range of the progressive mechanical stops330embodiments of the disclosed subject matter are not so limited. For instance, both the virtual stop320(2) and the virtual stop320(1) can be inside the operational range of the corresponding progressive mechanical stop330. Alternatively, both the virtual stop320(1) and the virtual stop320(2) can be outside the operational range of the corresponding progressive mechanical stop330. The virtual stops320may be implemented symmetrically, such as shown inFIG.3, or asymmetrically, for instance, based on operating characteristics of a particular machine100, characteristics or habits of the operator of the machine100, and/or characteristics of a particular worksite or task.

As shown inFIG.3, the virtual stop320(1) can be outside of the operational range of the corresponding progressive mechanical stop330, though alternatively, the virtual stop320(1) can be within the operational range of the corresponding progressive mechanical stop330. According to one or more embodiments, the virtual stops320(1) can represent initiation of a resistive force applied to the steering column214by the electric motor220, and the virtual stops320(2) can represent when a maximum resistive force is applied to the steering column214by the electric motor220, for instance.

Optionally, the maximum resistive force from the electric motor220can prevent the steering column214from further movement toward a corresponding hard mechanical stop332. Thus, in some instances, the maximum resistive force can set an absolute end stop for the steering column214. Such absolute end stop may be referred to herein as a virtual end stop. The virtual end stop may be within the operational range of the progressive mechanical stop330, such as shown inFIG.3, or alternatively prior to reaching the operational range of the progressive mechanical stop330. Limit, within the context of the second range of rotation302, can mean applying the resistive force using the electric motor220but still allowing rotational movement of the steering column214toward the hard mechanical stop332and/or applying the resistive force using the electric motor220to prevent any further movement of the steering column214toward the hard mechanical stop332, for instance, when the steering column214is at the virtual stop320(2).

Focusing on the specific, non-limiting example set forth inFIG.3, the hard mechanical stops332can define the first range of rotation300, the virtual stops320(2) can define the second range of rotation302, and the virtual stops320(1) can define the third range of rotation304. As shown, the rotational position of the steering column214may be determined to be at a rotational position P1, for instance, based on the position signals217from the sensor216.

At rotational position P1of the steering column214(as determined based on the position signals217from the position sensor216), a resistive force from the electric motor220may not be applied to the steering column214. That is, the controller218may control the electric motor220, via the control signals221, such that the electric motor220does not apply the resistive force to the steering column214. At the rotational position P1the steering column214has not activated (e.g., engaged) either progressive mechanical stop330.

As noted above, the virtual stop320(1) can define ends of the third range of rotation304as a position at which the controller218can control the electric motor220to initially provide the resistive force to the steering column214. Thus, the electric motor220can apply the resistive force when the steering column214is at rotational position P2, where the resistive force can be initiated at the virtual stop320(1). The resistive force applied to the steering column214at rotational position P2may be such that the steering column214is still allowed to be rotated toward the corresponding hard mechanical stop332. Note also that in this particular example at the rotational position P2the steering column214is not within the operational range of the progressive mechanical stop330.

As shown inFIG.3, the steering column214can continue moving toward the hard mechanical stop332and reach a rotational position P3, all the while under the resistive force of the electric motor220(which may be constant or increasing, for instance). At the rotational position P3the progressive mechanical stop330can be active (e.g., engaged by the steering column214). For instance, in the case of the progressive mechanical stop330in the form of a compliant member, a portion of the steering column214may be in contact with and compress the compliant member, which in response can provide a counter force (e.g., resistive force) to resist movement of the steering column214toward the hard mechanical stop332. Upon initiation of the progressive mechanical stop330, the resistive force applied by the electric motor220may continue increasing or may become constant or even decrease, for instance, since the progressive mechanical stop330is now also resisting movement of the steering column214toward the hard mechanical stop332.

Virtual stop320(2), as noted above, can be a position at which the electric motor220is controlled, in combination with the resistance provided by the progressive mechanical stop330, to provide a resistive force to the steering column214to prevent further rotation of the steering column214toward the hard mechanical stop332. Thus, the virtual stop320(2) may be a virtual end stop past which the steering column214is prevented from rotating, and the steering column214can be prevented from moving past rotational position P3.

Though the virtual stops320(2) are shown inFIG.3within the operational range of the progressive mechanical stops330, as noted above, alternatively, the virtual stops320(2) can be provided outside of the operational range of the progressive mechanical stops330. In this alternative embodiment, the virtual stop320(2) outside of the operational range of the progressive mechanical stop330may define the virtual end stop, or the end stop may still be defined somewhere within the operational range of the progressive mechanical stop330based on the combined resistive force applied by the progressive mechanical stop330and the electric motor220.

Optionally, the virtual stops320(1) and the virtual stops320(2) can be set in advance. Alternatively, the virtual stops320(1) and the virtual stops320(2), per side, can be set only when the steering column214is determined to be within a predetermined rotational distance from the progressive mechanical stop330or a portion thereof, such as the hard mechanical stop332. For instance, when the rotation position of the steering column214is on either side of a halfway mark in the first range of rotation the virtual stop320(1) and the virtual stop320(2) on that side may be set.

Virtual stops320, including virtual stops320(1) and virtual stops320(2), can be stored in memory, such as memory219discussed above. The virtual stops320can be stored in advance and/or stored as part of a training or calibration operation for later retrieval during operation of the machine100. The virtual stops320can be stored and/or created in correlation with various position-related characteristics of the steering column214, such as angular or rotational position of the steering column214, angular or rotational position of the steering column214with respect to one or more of the mechanical stops230, speed of rotation of the steering column214, rate of rotation of the steering column214, and/or direction of rotation of the steering column214. Thus, in one or more embodiments, the virtual stops320may be variable or vary, depending upon particular position-related characteristics of the steering column214, such as one or more of the foregoing position-related characteristics. Varying, in this context, can mean that the resistance applied by the electric motor220to the steering column214upon reaching the virtual stop320may be different depending upon particular position-related characteristics of the steering column214. Additionally or alternatively, varying can mean that where the virtual stop320occurs (e.g., is set) varies depending upon particular position-related characteristics of the steering column214.

For example, when the steering column214is relatively close to one of the progressive mechanical stops330and the speed or acceleration of rotation of the steering column214is toward the progressive mechanical stop330is determined to be relatively high (e.g., compared against a predetermined threshold, for instance, stored in the memory219), resistance provided by the electric motor220can start from a relatively high resistance upon the steering column214reaching the virtual stop320(1) as compared to a situation where the steering column214is relatively far away from the progressive mechanical stop330and/or the speed or acceleration of rotation toward the progressive mechanical stop330is relatively low. As another example, when the speed or acceleration of rotation of the steering column214toward one of the progressive mechanical stops330is relatively high, the virtual stop320(1) can be set such that the resistance applied by the electric motor220occurs relatively more quickly, effectively narrowing the inner-most range of rotation (e.g., third range304or second range302, depending upon whether one or two pairs of virtual stops320(1),320(2) are implemented).

FIG.4is a diagrammatic representation showing rotational range limitations for a steering wheel412as a control interface, which may be rotated clockwise and counterclockwise, implemented with stops according to one or more embodiments of the disclosed subject matter. Notably, the rotational range of the steering wheel412may be defined according to the mechanical stops430, particularly hard mechanical stops thereof (not expressly shown). Moreover, virtual stops420may be set within the rotational range provided by the mechanical stops430. When the steering wheel412is being turned in a direction toward one of the mechanical stops430and it at or between the corresponding virtual stop420and the one of the mechanical stops430, a counter resistive force may be applied to provide torque feedback to the steering wheel412. Such counter resistive force may be applied to the steering column by an electric motor operatively coupled to the steering column, and under the control of a controller, and felt at the steering wheel412as torque feedback. ThoughFIG.4shows only a single virtual stop420associated with each mechanical stop430, as noted above, more than one virtual stop420may be associated with each mechanical stop430, including, optionally, when the mechanical stop430in the form of a progressive mechanical stop is activated or in contact with the steering column.

INDUSTRIAL APPLICABILITY

As noted above, the present disclosure relates to electro-hydraulic (EH) steering systems that provide or implement at least one virtual stop and mechanical stop pairing.

For steering input in steer-by-wire systems it may be desirable to provide feedback to an operator to indicate an end position and/or an indication that the end position is upcoming. It may also be desirable to provide a mechanical stop in the form of a progressive mechanical stop. Such feedback and progressive mechanical stop can be useful to reduce or eliminate metal-to-metal contact of the steering column when the steering column is rotated to its rotational limits. Thus, embodiments of the disclosed subject matter may be characterized as a hybrid system that uses a mechanical stop in the form of a progressive mechanical stop in combination with torque feedback provided via operation of an electric motor. Such hybrid system can minimize the amount of rotational angle consumed by the progressive mechanical stop (i.e., minimize the amount of limit to the angular rotation of the steering column) while at the same time providing a supplement to the progressive mechanical stop by way of a torque feedback system that applies a resistive force from an electric motor to the steering column. Put another way, embodiments of the disclosed subject matter can implement progressive mechanical stops in combination with electrical motor-based torque feedback to provide sufficient tactile feedback without unduly limiting or consuming angular rotation of the steering column.

Turning toFIG.5,FIG.5is a flow chart of a method500according to one or more embodiments of the disclosed subject matter.

The method500can be performed by a steering system, such as steering system200ofFIG.2. A controller, such as controller218, can perform or control some or all of the operations of the method500. Additionally, the method500may be performed according to a non-transitory computer-readable storage medium, such as memory219, that stores computer-readable instructions that, when executed by a computer (e.g., a processor or microprocessor of controller218), cause the computer to perform the method500.

At502position signals, such as position signals217, can be received. Such position signals217can be received by the controller218, for instance, from one or more sensors, such as sensor216. As noted above, the position signals217can correspond to rotational position of a steering column, such as steering column214.

At504at least one position-related characteristic of the steering column214can be determined based on the received position signals217. The controller218can process the position signals217to determine the at least one of the steering column214. As noted above, position-related characteristics can include angular or rotational position of the steering column214, angular or rotational position of the steering column214with respect to one or more of the mechanical stops230, rotation speed of the steering column214, rotational acceleration of the steering column214, and/or direction of rotation of the steering column214.

At506the method500can determine whether the at least one position-related characteristic indicates that a resistive force is to be applied to the steering column214. The controller218can perform processing to determine whether the at least one position-related characteristic indicates that the resistive force is to be applied to the steering column214. Such processing can include comparing the determined position of the steering column214relative to one or more mechanical stops230, such as progressive mechanical stops330(or portions thereof), and/or one or more virtual stops320, such as virtual stops320(1) and/or320(2). The processing may also factor in as position-related characteristics the determined rotational speed, rotational acceleration, and/or rotational direction of the steering column214.

In that the determining of whether to apply the resistive force can be based on one or more virtual stops320, such as virtual stops320(1) and virtual stops320(2) ofFIG.3, the one or more virtual stops320can be stored in memory, such as memory219ofFIG.2. The memory219can store, in a lookup table, for instance, the one or more virtual stops (e.g., virtual end stops)320to selectively control application of the resistive force by the electric motor220. Such virtual stops320can be stored in correlation with various position-related characteristics of the steering column214, such as angular or rotational position of the steering column214, angular or rotational position of the steering column214with respect to one or more of the mechanical stops230, rotation speed of the steering column214, rotational acceleration of the steering column214, and/or direction of rotation of the steering column214, and can be accessed by the controller218to control the electric motor220to apply the resistive force to the steering column214.

If by the processing of the at least one position-related characteristic it is determined that the resistive force is not to be applied, for instance, because the steering column214is within a rotational range (e.g., the third rotational range304) where no resistive force is needed, control can return to502. On the other hand, if by the processing of the at least one position-related characteristic it is determined that the resistive force is to be applied, at512the resistive force can be applied to the steering column214. The controller218can control an electric motor, such as electric motor220, to apply the resistive force to the steering column214. Application of the resistive force can be initiated from a first state where the electric motor220does not apply any resistive force to the steering column214to a second state where the electric motor220applies the resistive force to the steering column214. As non-limiting examples, application of the resistive force can increase after initiation, for instance, linearly or exponentially, as the steering column214is moved toward a mechanical stop, such as mechanical stop230; the resistive force can remain constant, for instance, when the steering column214remains at the same position; and the resistive force can decrease (after initiation) and ultimately stop being applied to the steering column214when the steering column214is moved away from the mechanical stop230.

Application of the resistive force to the steering column214can be based on the determined position of the steering column214relative to one or more mechanical stops230, one or more virtual stops320, and/or other position-related characteristics including rotational speed, rotational acceleration, and rotational direction of the steering column214.

In a case where one or more virtual stops320may not be set in advance, the method500can optionally perform a dynamic setting of the one or more virtual stops320responsive to the at least one position-related characteristic indicating that the resistive force is to be applied and based on the actual determined at least one position-related characteristic.

In particular, at508the method500can determine whether one or more virtual stops320are to be dynamically set. When the method500includes the dynamic setting of the one or more virtual stops320, at510the one or more virtual stops320can be set based on various position-related characteristics of the steering column214, such as angular or rotational position of the steering column214, angular or rotational position of the steering column214with respect to one or more of the mechanical stops230, speed of rotation of the steering column214, rotational acceleration of the steering column214, and/or direction of rotation of the steering column214. Application of the resistive force to the steering column214by the electric motor220can be implemented at512, under control of the controller218, based on the dynamically set virtual stop(s)320and the various position-related characteristics of the steering column214.