GB2567184A

GB2567184A - Vehicle steering system

Info

Publication number: GB2567184A
Application number: GB1716247.0A
Authority: GB
Inventors: Irinics Aleksejs
Original assignee: Arrival Ltd
Current assignee: Arrival UK Ltd
Priority date: 2017-10-05
Filing date: 2017-10-05
Publication date: 2019-04-10
Anticipated expiration: 2037-10-05
Also published as: GB2567184B; GB201716247D0

Abstract

A vehicle steering system 1 includes an input shaft 8 coupled to a steering wheel 2, a steering shaft 9 coupled to a steering box 3 and a decoupling assembly 7 between input shaft 8 and steering shaft 9. Decoupling assembly 7 includes a coupling member moveable using an actuator, which may be a hydraulic or pneumatic actuator or a linear actuator with an electric motor, between a coupled position in which input shaft 8 is rotationally coupled to steering shaft 9 and a decoupled position in which input shaft 8 is rotationally decoupled from steering shaft 9. The coupling may comprise a spline coupling. The system is particularly suitable for road vehicles such as cars, vans, trucks and buses, and may be used with autonomous vehicles.

Description

Vehicle Steering System

Field of the Invention

The present invention relates to a vehicle steering system, the steering system being arranged to link a steering wheel to a steering box of the vehicle.

Background

Road vehicles typically have a steering column that couples the steering wheel to the steering box, which in turns actuates movement of the front wheels and/or rear wheels 10 to direct the vehicle during use. A steering box usually includes a steering gear and other linkages for moving the wheels in response to rotational input, and may be power assisted by hydraulic or electric actuators. Typically the steering column includes a number of rotating shafts linked together by universal joints, constant velocity joints, and/or bevel gears so that the shafts transmit rotation of the steering wheel to the steering box for steering the wheels.

Summary of the Invention

In accordance with some embodiments, there is provided a vehicle steering system comprising an input shaft arranged to be coupled to a steering wheel, a steering shaft 20 arranged to be coupled to a steering box, and a decoupling assembly arranged between the input shaft and the steering shaft, the decoupling assembly comprising a coupling member and an actuator configured to move the coupling member between a coupled position in which the coupling member rotationally couples the input shaft to the steering shaft, and a decoupled position in which the input shaft is rotationally decoupled from the steering shaft.

In some examples, the vehicle steering system may further comprise a biasing member arranged to bias the coupling member towards the coupled position. In some examples, the actuator comprises the biasing member.

In preferred examples, the coupling member comprises a coupling shaft that is slidably coupled to the input shaft and slidably coupled to the steering shaft. The coupling shaft may be adapted to disengage from one of the input shaft and the steering shaft when it 5 is moved by the actuator into the decoupled position.

The coupling between the coupling shaft and the input shaft may comprise a spline coupling. Similarly, the coupling between the coupling shaft and the steering shaft may comprise a spline coupling.

The spline coupling or couplings may comprise a splined section and a spline hub.

In some examples, the coupling shaft comprises a splined hub for slidably coupling to a splined section of the input shaft and/or a splined section of the steering shaft.

In some examples, the coupling shaft comprises a splined section for slidably coupling to a splined hub of the input shaft and/or the steering shaft.

In a preferred example, the coupling shaft comprises a splined section for slidably coupling to a splined hub of the steering shaft, and a splined hub for slidably coupling 20 to a splined section of the input shaft.

The coupling shaft may comprise a spline section for slidably coupling to a splined hub of the input shaft, and a splined hub for slidably coupling to a splined section of the steering shaft.

-3In some examples, the input shaft may comprise a first friction plate and the coupling member may comprise a second friction plate, and the actuator may be arranged to move the first and second friction plates into and out of engagement with each other.

The actuator may comprise a linear actuator adapted to slide the coupling member between the coupled position and the decoupled position.

The actuator may comprise a ball screw, a ball nut that is attached to the coupling member and to the ball screw, and a motor arranged to rotate the ball screw such that 10 the ball nut is moved linearly along the ball screw.

Alternatively, the actuator may comprise a hydraulic actuator adapted to act on the coupling member. Alternatively, the actuator may comprise a pneumatic actuator adapted to act on the coupling member.

In various examples, the coupling shaft comprises a threaded section having an external thread, and the actuator comprises a screw nut arranged to engage the external thread. The actuator may further comprise a motor arranged to rotate the screw nut to move the coupling shaft in a linear direction.

The screw nut may comprise a pulley, and the actuator may further comprise a belt drive arranged to rotate the screw nut via the pulley.

Alternatively, the actuator may comprise an electric motor arranged to rotate the screw nut. The electric motor may be arranged concentrically about the coupling shaft.

-4The screw nut may comprise a rotor of the electric motor, and a stator may be arranged concentrically about the screw nut. The stator may be fixed to a chassis of said vehicle such that the electric motor drives rotation of the screw nut.

In various examples, the vehicle steering system further comprises a sliding bearing arranged to support the coupling member.

In examples, the vehicle steering system further comprises a sensor arranged to detect rotation of the input shaft. The vehicle steering system may additionally comprise a 10 sensor arranged to detect rotation of the steering shaft.

The vehicle steering system may further comprise a controller configured to receive information from the sensors.

In some examples, the controller may be configured to control the actuator of the decoupling assembly.

The vehicle steering system may further comprise an actuator arranged to rotate the input shaft. In this example, the controller may be configured to control the actuator to 20 rotate the input shaft into a corresponding position of the steering shaft prior to coupling the input shaft to the steering shaft.

In some examples, the vehicle steering system may further comprise a steering actuator configured to rotate the steering shaft. In this example, the controller may be further 25 configured to control the steering actuator during autonomous steering.

-5According to a further aspect of the present invention, there is also provided a vehicle comprising the vehicle steering system described above.

In some examples, the vehicle is a road vehicle. In some examples, the vehicle is a commercial vehicle, for example a goods vehicle such as a heavy goods vehicle. In other examples, the vehicle is a car, van, truck, or bus. The vehicle maybe a hybrid, rangeextended, and/or electric vehicle.

According to a further aspect of the present invention, there is also provided a controller for a vehicle steering system, the vehicle steering system comprising an input shaft, a steering shaft, and a decoupling mechanism arranged between said input shaft and said steering shaft, said decoupling mechanism having a coupling member and an actuator, wherein the controller is configured to control operation of said actuator to move said coupling member between a coupled position in which said coupling member rotationally couples said input shaft to said steering shaft, and a decoupled position in which said input shaft is rotationally decoupled from said steering shaft.

The controller may be further configured to provide autonomous steering to said vehicle.

According to a further aspect of the present invention, there is also provided a method of controlling a steering system of a vehicle, said steering system comprising an input shaft, a steering shaft, and a coupling member arranged between said input shaft and said steering shaft, and wherein the method comprises the step of moving the coupling 25 member between a coupled position in which the coupling member rotationally couples the input shaft to the steering shaft, and a decoupled position in which the input shaft is rotationally decoupled from the steering shaft.

-6The method may further comprise the steps of detecting the rotational position of the input shaft and the rotational position of the steering shaft, and rotationally aligning the input shaft and the steering shaft prior to moving the coupling member from the decoupled position to the coupled position.

The method may further comprise the step of moving the coupling member from the decoupled position to the coupled position when rotation of the input shaft is detected.

The method may further comprise the step of moving the coupling member from the decoupled position to the coupled position when a user input is detected.

The method may further comprise the step of autonomously steering said vehicle when the coupling member is in the decoupled position.

The step of autonomously steering said vehicle may comprise controlling a steering motor arranged to rotate the steering shaft.

According to a further aspect of the present invention, there is also provided apparatus 20 comprising means for performing the above-described method.

According to a further aspect of the present invention, there is also provided computerreadable instructions which, when executed by computing apparatus, cause the computing apparatus to perform the above-described method.

Brief Description of the Drawings

-7Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 shows a steering system for a vehicle, including a steering linkage;

FIG. 2 shows a first example decoupling assembly;

FIG. 3 shows a second example decoupling assembly;

FIG. 4 shows a third example decoupling assembly;

FIG. 5 shows a fourth example decoupling assembly; and

FIG. 6 shows a schematic system diagram for the steering system.

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Detailed Description

As illustrated in FIG. 1, the steering system 1 includes a steering wheel 2 and a steering box 3. The steering wheel 2 is located in the front of the vehicle, where the driver is located, and the steering box 3 is located in the undercarriage of the vehicle. The steering linkage 4 transmits rotational movement of the steering wheel 2 to the steering box 3. The steering box 3 actuates steering movement of the wheels 6 by pushing and/or pulling on a part of the wheel 6 or wheel carrier (not shown) to pivot the wheels

6.

The steering box 3 may be of any type, for example the steering box may have a ‘rack and pinion’ arrangement that translates rotational input into sideways movement of a steering rack to move the wheels 6. Alternatively, the steering box 3 maybe a ‘worm and sector’ type, or a ‘screw and nut’ type. Each of these types of steering box 3 are known by the skilled person, and so detailed description is omitted. In addition, the steering box 3 may be power assisted. That is, the steering system 1 may include a hydraulic or electric system (not shown) that applies a force to assist movement of the steered wheels 6.

A vehicle typically has a chassis with front wheels and rear wheels, and the front wheels are usually actuated by the steering system 1 to control the direction of the vehicle. The steering system 1 may act to move the front wheels 6 of the vehicle. However, the steering linkage 4 described herein could alternatively be used to move the rear wheels, or other wheels of a vehicle, and can be used for two-wheel or four-wheel steering. In some vehicles, particularly large goods vehicles, more than one wheel on each side of the vehicle is steered. In this case, the steering system 1 described herein can act to steer multiple wheels on each side of the vehicle.

-8In addition, the steering system 1 described herein, particularly the steering linkage 4, may be used in any vehicle, for example a car, van, bus, truck, lorry, or other vehicle. For reasons explained further hereinafter, the steering linkage 4 disclosed herein may 5 be particularly advantageous when used in a goods vehicle, for example a truck or a heavy goods vehicle. The vehicle may have any kind of drive train. For example, the vehicle may have a conventional internal combustion engine, an electric range extender, an electric motor, or any combination of these.

For convenience, in the described examples the steering box 3 is a ‘rack and pinion’ steering box 3 that is adapted to move the steering arms 5 sideways in response to rotational input, as illustrated in FIG. 2. The steering arms 5 are coupled to the wheels or wheel carriers (not illustrated), so that the wheels 6 pivot in response to the sideways movement of the steering arms 5.

As also illustrated in FIG. 1, the steering system 1 includes a decoupling assembly 7. The decoupling assembly 7 is disposed between an input shaft 8 that is coupled to the steering wheel 2 and a steering shaft 9 that is coupled to the steering box 3. The input shaft 8 is rotated with the steering wheel 2, and the steering shaft 3 provides rotation to 20 the steering box 3 for steering the wheels 6.

As shown in FIG. 1, the steering linkage 4 includes a steering wheel shaft 10 to which the steering wheel 2 is mounted and a gear shaft 12 coupled to the steering wheel shaft 10 by a universal joint 11. Rotation of the steering wheel 2 is thereby transmitted to the 25 first bevel gear 13, which is attached to an end of the gear shaft 12. A second bevel gear is attached to the input shaft 8, so that the input shaft 8 is rotationally coupled to the steering wheel 2.

However, it will be appreciated that the steering linkage 4 may vary from the illustrated 30 example, and any arrangement of shafts, gears, constant velocity joints, flexible shafts, and/or universal joints may be arranged between the steering wheel 2 and the steering box 3. In the simplest example, the steering wheel is attached directly to the input shaft

8.

Preferably, as illustrated, the steering shaft 9 directly couples the decoupling assembly to the steering box 3. However, it will be appreciated that further shafts, gears, constant velocity joints, flexible shafts, and/or universal joints maybe provided between the decoupling assembly 7 and the steering box 3.

The decoupling assembly 7 is arranged to allow the input shaft 8 to be decoupled from the steering shaft 9. In this way, movement of the steering shaft 9 and/or the steering box 3 is not transmitted back to the steering wheel 2, and likewise rotation of the steering wheel 2 is not transmitted to the steering box 3. In various examples, the decoupling assembly 7 includes a coupling member and an actuator arranged to move the coupling member to selectively decouple the input shaft and the steering shaft. For example, the actuator may move the coupling member between a position in which the input shaft 8 is coupled to the steering shaft 9, and a position in which the input shaft 8 is decoupled from the steering shaft 9.

In some examples, the input shaft 8 is decoupled from the steering shaft 9 during autonomous steering, when a motor directly drives rotation of the steering shaft 9 and/or steering box 3 without input from user via the steering wheel 2. Therefore, during autonomous steering the steering wheel 2 will not be rotating in front of the user, which may be distracting and dangerous. Instead, the steering wheel 2 will remain stationary during autonomous steering. In addition, once the input shaft 8 is decoupled 20 from the steering shaft 9 the motor that drives the autonomous steering does not have to rotate the steering linkage 4 and steering wheel 2, which can make the autonomous steering more efficient and reactive as there are fewer components being driven by the autonomous steering motor.

FIG. 2 illustrates a first example of the decoupling assembly 7. The decoupling assembly 7 is disposed between the input shaft 8 and the steering shaft 9.

As illustrated, the decoupling assembly 7 includes a coupling member, and in this example the coupling member is an intermediate shaft 15. An end 16 of the input shaft 30 8 has a spline section 17 arranged to couple with a spline hub 18 formed in an end 19 of the intermediate shaft 15.

The spline section 17 on the input shaft 8 comprises one or more splines formed on the outer surface of the input shaft 8, and the spline hub 18 comprises one or more splines 35 protruding from the interior surface of a recess formed in the end 19 of the intermediate shaft 15. The splines on the spline section 17 are configured to cooperate

- 10 with the splines on the spline hub 18 so that they form a sliding connection, and when the spline section 17 and spline hub 18 at least partially overlap the input shaft 8 is rotationally coupled to the intermediate shaft 15.

The spline section 17 and spline hub 18 thereby form a coupling that can be decoupled by moving the intermediate shaft 15 axially so that the spline section 17 and spline hub 18 no longer overlap, as shown in FIG. 2.

The other end 20 of the intermediate shaft 15 has a spline section 21 arranged to cooperate with a spline hub 22 formed in the end 23 of the steering shaft 9 in a similar manner to as described above. However, the spline section 21 and spline hub 22 are longer axially than the spline section 17 and spline hub 18, so that they do not decouple when the intermediate shaft 15 is moved. The spline section 21 and spline hub 22 permit sliding movement of the intermediate shaft 15 so that the intermediate shaft 15 can decouple from the input shaft 8, while retaining a rotational coupling between the intermediate shaft 15 and the steering shaft 9.

In this way, the intermediate shaft 15 is slidably mounted to both the input shaft 8 and steering shaft 9, and can be moved axially to decouple the input shaft 8 and the steering 20 shaft 9.

An actuator 24 is provided to move the intermediate shaft 15. As illustrated, in this example the actuator 24 includes a ball screw 25 having a screw shaft 26 and a ball 27. The screw shaft 26 is mounted between a part of the chassis 29 of the vehicle and an 25 electric motor 28 so that it is in a fixed position and the motor 28 can drive rotation of the screw shaft 26. The ball 27 is arranged at the end of a moving member 30 that is also attached to the intermediate shaft 15 via a roller bearing 56. The moving member 30 is rotationally coupled to the intermediate shaft 15 at roller bearing 56 such that the intermediate shaft 15 can rotate independently of the moving member 30, but axial 30 movement of the moving member 30 is transferred to the intermediate shaft 15.

The ball 27 engages the screw shaft 26 such that rotation of the screw shaft 26 by the motor moves the ball 27, and the moving member 30, axially along the screw shaft 26. The screw shaft 26 is axially parallel to, and spaced from, the axes of the input shaft 8, 35 intermediate shaft 15, and steering shaft 9. In this way, the motor 28 can be controlled

- 11 to move the intermediate shaft 15 into and out of engagement with the input shaft 8, as desired.

As also illustrated in FIG. 2, a roller bearing 31 is mounted in a part of the chassis 29 and supports the input shaft 8 close to the spline section 17. Similarly, a roller bearing is mounted to a part of the chassis 29 and supports the steering shaft 9 close to the spline hub 22. A sliding bearing 33 is mounted to a part of the housing (not shown) to support the intermediate shaft 15. The sliding bearing 33 is preferably a bushing, or similar, that can support the intermediate shaft 15 during sliding and rotation.

During operation, when the intermediate shaft 15 couples the input shaft 8 to the steering shaft 9, all three shafts 8,15, 9 are rotated during steering but this rotation is not transferred back to the actuator 24 because of the roller bearing 56 between the intermediate shaft 15 and moving member 30.

FIG. 3 illustrates another example of the decoupling assembly 7. In this example, the intermediate shaft 15 is slidably coupled to the input shaft 8 in the same manner as described with reference to FIG. 2, i.e. via spine section 17 and spline hub 18, and is also slidably coupled to the steering shaft 9 in the same manner as described with 20 reference to FIG. 2, i.e. via spline section 21 and spline hub 22. Roller bearings 31,32 support the input shaft 8 and steering shaft 9, respectively, and sliding bushing 33 supports the intermediate shaft 15.

In this example, the intermediate shaft 15 has a threaded section 34, having an external 25 thread. The actuator 24 comprises a screw nut 35 that is rotationally mounted to the chassis 29 by bearings 36 in such a way that the axial position of the screw nut 35 is fixed and the screw nut 35 can rotate about the axis due to the bearings 36. The screw nut 35 has in internal thread 37 arranged to cooperate with the external thread 34 on the intermediate shaft 15. The screw nut 35 also includes a pulley section 38 arranged 30 to be rotationally driven by a pulley belt 39 that is driven by drive pulley 40 and motor

28.

In this way, when the motor 28 drives the drive pulley 40 and belt 39 the screw nut 35 is rotated by the pulley section 38 and the thread 34,37 causes axial sliding of the intermediate shaft 15. The direction of the motor 28 can be changed to move the intermediate shaft 15 in the opposite directions.

- 12 In the coupled position, i.e. when spline section 19 overlaps with spline hub 18, the motor 28 is depowered, such that the intermediate shaft 15 is free to rotate under steering action from the steering wheel 2, which in turn causes rotation of the motor 5 28.

A locking mechanism (not illustrated), for example a solenoid-actuated pin lock, is arranged to lock the screw nut 35 to the intermediate shaft 15 when the input shaft 8 is coupled to the intermediate shaft 15 for manual steering. The locking mechanism is also 10 arranged to disengage to allow the intermediate shaft 15 to move out of engagement with the input shaft 8. The locking mechanism prevents the intermediate shaft 15 from moving during rotation of the input shaft 8 during manual steering. When the locking mechanism is engaged and the screw nut 35 is locked to the intermediate shaft 15, rotation of the intermediate shaft 15 (via the input shaft 8) will cause the motor to be 15 rotated.

FIG. 4 illustrates a further example of the decoupling assembly 7. In this example, the intermediate shaft 15 is slidably coupled to the input shaft 8 in the same manner as described with reference to FIG. 2, i.e. via spine section 17 and spline hub 18, and is 20 also slidably coupled to the steering shaft 9 in the same manner as described with reference to FIG. 2, i.e. via spline section 21 and spline hub 22. Roller bearings 31,32 support the input shaft 8 and steering shaft 9, respectively, and sliding bushing 33 supports the intermediate shaft 15.

The intermediate shaft 15 is also provided with a threaded section 41, having an external thread. In this example, the actuator 24 comprises a screw nut 42 that has an internal thread 43 that cooperates with the external thread on the threaded section 41 of the intermediate shaft 15. As illustrated, the screw nut 42 in this example forms the rotor of an electric motor 44, which forms the actuator 24. A rotor part 45 of the screw nut 42 includes components required of the rotor of an electric motor 44. A stator 46 is arranged about the rotor part 45 of the screw nut 42, and together with the rotor part 45 forms the electric motor 44. The stator 46 is mounted to the chassis 29. The screw nut is mounted to the chassis such that it is able to rotate but cannot move axially.

In this way, when the electric motor 44 is driven and screw nut 42 rotates and the thread 41,43 between the screw nut 42 and the intermediate shaft 15 moves the

-13intermediate shaft 15 axially to couple / decouple the input shaft 8 and the steering shaft 9.

A locking mechanism (not illustrated), for example a solenoid-actuated pin lock, is arranged to lock the screw nut 42 (rotor part 45) to the intermediate shaft 15 when the input shaft 8 is coupled to the intermediate shaft 15 for manual steering. The locking mechanism is also arranged to disengage to allow the intermediate shaft 15 to move out of engagement with the input shaft 8. The locking mechanism prevents the intermediate shaft 15 from moving during rotation of the input shaft 8 during manual steering.

In an alternative example, the stator 46 of the electric motor 44 may be attached to the steering shaft 9. For example, the steering shaft 9 may comprise a protruding tubular member to which the stator 44 is attached. In this way, the entire electric motor 44 15 rotates together with the input shaft 8, intermediate shaft 15 and steering 9 when the three shafts 8,15, 9 are coupled to each other. Driving the electric motor 44 to rotate the screw nut 42 relative to the stator 46 will then move the intermediate shaft 45 linearly to disengage / engage the intermediate shaft 15 and input shaft 8.

In the examples of FIGS. 2 to 4, the intermediate shaft 15 can be decoupled from the input shaft 8 by sliding the intermediate shaft 15 such that the spline coupling 17,18 decouples, while the intermediate shaft 15 remains rotationally coupled to the steering shaft 9 via spline coupling 21, 22. However, it will be appreciated that the spline couplings may be alternatively arranged such that the intermediate shaft 15 is decoupled from the steering shaft 9 and remains rotationally coupled to the input shaft

8.

In an alternative example, schematically illustrated in FIG. 5, the decoupling assembly 30 includes a friction plate arrangement, for example a clutch. In this example, the input shaft 8 is provided is a first friction plate 57, and the intermediate shaft 15 is provided with a second friction plate 58. An actuator 24 is provided to move the intermediate shaft 15 such that the second friction plate 58 moves into and out of engagement with the first friction plate 57 to couple and decouple the input shaft 8 from the steering shaft 9. The intermediate shaft 15 is slidably coupled to the steering shaft 9 in the same manner as previously described with reference to FIGS. 2 to 4.

-14The actuator 25 may comprise a linear actuator, for example a ball screw 25 similar to that described with reference to FIG. 2. As illustrated, the actuator 24 is coupled to the intermediate shaft 15 via a bearing 56 so that the intermediate shaft 15 can rotate and the actuator 24 can move the intermediate shaft 15 axially.

In alternative examples having the friction plates 57, 58 of FIG. 5, the actuator 24 may comprise an electric motor 28 and screw nut 35 similar to that described with reference to FIG. 3, or an electric motor 44 similar to that described with reference to FIG. 4, to move the intermediate shaft 15 between the coupled and decoupled positions.

In alternative examples, the actuator may be arranged to move the first friction plate instead of the second friction plate, or the actuator may be arranged to move both of the first and second friction plates.

As illustrated in FIGS. 2 to 5, the decoupling assembly 7 also includes an input shaft sensor 47 arranged to detect rotational position and/or rotational rate of the input shaft

8. In this example, the input shaft sensor 47 is arranged to detect markings 48 on the input shaft 8.

As also illustrated in FIGS. 2 to 5, the decoupling assembly 7 also includes a steering shaft sensor 49 arranged to detect rotational position and/or rotational rate of the steering shaft 9. In this example, the steering shaft sensor 49 is arranged to detect markings 50 on the steering shaft 9.

In embodiments, the steering system 1 further includes a controller arranged to receive information from the input shaft sensor 47 and the steering shaft sensor 49. The controller may also be configured to control the actuator 24.

A schematic diagram of a control system 51 is shown in FIG. 6. As shown, the input shaft sensor 47 is connected to the controller 51 via connection 52, and the steering shaft sensor 49 is connected to the controller 51 via connection 53. The controller 51 is configured to receive information from the input shaft sensor 47 about the position and/or rotational speed of the input shaft 8. The controller 51 is also configured to receive information from the steering shaft sensor 49 about the position and/or rotational speed of the steering shaft 9. The controller 51 is also configured to control

-ι₅the actuator 24, via connection 54, in order to move the intermediate shaft 15 between a coupled position and a decoupled position, as described above.

In some examples, the controller 51 is further configured to control an autonomous steering motor 55 that acts directly on the steered wheels 6 or other steering linkage to provide autonomous steering. Autonomous steering may include, for example, autonomous driving or automatic parking.

In some examples, the controller 51 is configured to control the actuator 24 such that the input shaft 8 is decoupled from the steering shaft 9 during an autonomous steering mode. Further, when changing from an autonomous steering mode to a manual steering mode the controller 51 may be configured to move the intermediate shaft 15 to couple the input shaft 8 to the steering shaft 9.

In one example, the driver uses an actuator, for example a button or lever, to change between manual and autonomous steering modes. Alternatively, or additionally, if the steering system 1 is in an autonomous steering mode, then manual rotation of the steering wheel 2 maybe detected by the input shaft sensor 47, and the controller 51 may be configured to move the intermediate shaft 15 to couple the input shaft 8 to the 20 steering shaft 9 on detection of steering wheel 2 movement during an autonomous steering mode.

In another example, the steering wheel 2 may include a sensor arranged to detect when the steering wheel 2 is being held by the driver, and the controller 51 can be configured to initiate change from autonomous to manual steering when the sensor detects that the driver has taken hold of the steering wheel 2. In examples, the sensor may be a button, lever, proximity sensor, or a capacitive sensor.

In some examples, the controller 51 is configured to match the rotational position of the 30 input shaft 8, and thus the steering wheel 2, with the rotational position of the steering shaft 9, and thus the steering box. In this example, a further motor maybe provided to rotate the input shaft 8 into the desired rotational position prior to moving the intermediate shaft 15 to couple the input shaft 8 to the steering shaft 9. The rotational position of the input shaft 8 and the steering shaft 9 may be determined by the input shaft sensor 47 and steering shaft sensor 49.

-16In other examples, the controller 51 does not match the rotational position of the input shaft 8, and thus the steering wheel 2, with the rotational position of the steering shaft 9, and thus the steering box prior to moving the intermediate shaft 15 to couple the input shaft 8 to the steering shaft 9. In these examples, the controller 51 moves the intermediate shaft 15 to couple the input shaft 8 to the steering shaft 9 to change from an autonomous steering mode to a manual steering mode. In this case, the steering wheel 2 may be spokeless, or symmetrical, or a disc, such that the steering wheel 2 appearance is not related to the steering position of the wheels 6. In this way, the input shaft 8, and therefore the steering wheel 2, can be coupled to the steering shaft 9 in any 10 rotational position.

Therefore, an example method of changing from manual to autonomous steering includes the actuator 24 moving the intermediate shaft 15 to decouple the input shaft 8 from the steering shaft 9.

An example method of changing from autonomous steering to manual steering comprises moving the intermediate shaft 15 to couple the input shaft 8 to the steering shaft 9.

An alternative example method of changing from autonomous steering to manual steering comprises:

• detecting a rotational position of the input shaft 8, • detecting a rotational position of the steering shaft 9, • aligning the rotational position of the input shaft 8 to the rotational position of the steering shaft 9, and • moving the intermediate shaft 15 to couple the input shaft 8 to the steering shaft 9·

The methods may further include a step of detecting rotation of the input shaft 8, which 30 can trigger the method described above. Rotation of the input shaft 8 indicates that the driver is rotating the steering wheel 2, and may be interpreted as a command to change to manual steering.

In order to address various issues and advance the art, the entirety of this disclosure 35 shows by way of illustration various embodiments in which the claimed invention(s)

-17may be practiced and provide for a superior vehicle steering system. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/or exclusive. They are presented only to assist in understanding and teach the claimed features. It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications maybe made without departing from the scope and/or spirit of the disclosure. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. In addition, the disclosure includes other inventions not presently claimed, but which may be claimed in future.

Claims

1. A vehicle steering system comprising an input shaft arranged to be coupled to a steering wheel, a steering shaft arranged to be coupled to a steering box, and a

5 decoupling assembly arranged between the input shaft and the steering shaft, the decoupling assembly comprising a coupling member and an actuator configured to move the coupling member between a coupled position in which the coupling member rotationally couples the input shaft to the steering shaft, and a decoupled position in which the input shaft is rotationally decoupled from the steering shaft.

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2. The vehicle steering system of claim 1, further comprising a biasing member arranged to bias the coupling member towards the coupled position.

3. The vehicle steering system of claim 2, wherein the actuator comprises the

15 biasing member.

4. The vehicle steering system of any preceding claim, wherein the coupling member comprises a coupling shaft that is movably coupled to the input shaft and movably coupled to the steering shaft, and wherein the coupling shaft is adapted to

20 disengage from one of the input shaft and the steering shaft when it is moved by the actuator into the decoupled position.

5. The vehicle steering system of claim 4, wherein the coupling between the coupling shaft and the input shaft comprises a spline coupling.

6. The vehicle steering system of claim 4 or claim 5, wherein the coupling between the coupling shaft and the steering shaft comprises a spline coupling.

7- The vehicle steering system of claim 5 or claim 6, wherein the spline coupling comprises a splined section and a spline hub.

5

8. The vehicle steering system of claim 7, wherein the coupling shaft comprises a splined hub for slidably coupling to a splined section of the input shaft and/or a splined section of the steering shaft.

9. The vehicle steering system of claim 7 or claim 8, wherein the coupling shaft

10 comprises a splined section for slidably coupling to a splined hub of the input shaft and/or the steering shaft.

10. The vehicle steering system of any of claims 6 to 9, wherein the coupling shaft comprises a splined section for slidably coupling to a splined hub of the steering shaft,

15 and a splined hub for slidbly coupling to a splined section of the input shaft.

11. The vehicle steering system of any of claims 6 to 9, wherein the coupling shaft comprises a spline section for slidably coupling to a splined hub of the input shaft, and a splined hub for slidbly coupling to a splined section of the steering shaft.

12. The vehicle steering system of any of claims 1 to 4, wherein the input shaft comprises a first friction plate and the coupling member comprises a second friction plate, and wherein the actuator is arranged to move the first and second friction plates into and out of engagement with each other.

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13· The vehicle steering system of any preceding claim, wherein the actuator comprises a linear actuator adapted to slide the coupling member between the coupled position and the decoupled position.

5

14. The vehicle steering system of claim 13, wherein the actuator comprises a ball screw, a ball nut that is attached to the coupling member and to the ball screw, and a motor arranged to rotate the ball screw such that the ball nut is moved linearly along the ball screw.

10 15. The vehicle steering system of claim 13, wherein the actuator comprises a hydraulic actuator adapted to act on the coupling member.

16. The vehicle steering system of claim 13, wherein the actuator comprises a pneumatic actuator adapted to act on the coupling member.

17. The vehicle steering system of claims 4 to 11, wherein the coupling shaft comprises a threaded section having an external thread, and the actuator comprises a screw nut arranged to engage the external thread, and wherein the actuator further comprises a motor arranged to rotate the screw nut to move the coupling shaft in a

20 linear direction.

18. The vehicle steering system of claim 17, wherein the screw nut comprises a pulley, and wherein the actuator further comprises a belt drive arranged to rotate the screw nut via the pulley.

19- The vehicle steering system of claim 17, wherein the actuator comprises an electric motor arranged to rotate the screw nut, and wherein the electric motor is arranged concentrically about the coupling shaft.

5 20. The vehicle steering system of claim 19, wherein the screw nut comprises a rotor of the electric motor, and a stator is arranged concentrically about the screw nut, the stator being fixed to a chassis of said vehicle such that the electric motor drives rotation of the screw nut.

10 21. The vehicle steering system of any preceding claim, further comprising a sliding bearing arranged to support the coupling member.

22. The vehicle steering system of any preceding claim, further comprising a sensor arranged to detect rotation of the input shaft.

23. The vehicle steering system of claim 22, further comprising a sensor arranged to detect rotation of the steering shaft.

24. The vehicle steering system of claim 23, further comprising a controller

20 configured to receive information from the sensor.

25. The vehicle steering system of claim 24, wherein the controller is configured to control the actuator of the decoupling assembly.

25 26. The vehicle steering system of claim 24 or claim 25, further comprising an actuator arranged to rotate the input shaft, and wherein the controller is configured to

- 22 control the actuator to rotate the input shaft into a corresponding position of the steering shaft prior to coupling the input shaft to the steering shaft.

27. The vehicle steering system of any of claims 24 to 26, further comprising a

5 steering actuator configured to rotate the steering shaft, and wherein the controller is further configured to control the steering actuator during autonomous steering.

28. A vehicle comprising the vehicle steering system of any preceding claim.

10 29. A controller for a vehicle steering system, the vehicle steering system comprising an input shaft, a steering shaft, and a decoupling mechanism arranged between said input shaft and said steering shaft, said decoupling mechanism having a coupling member and an actuator, wherein the controller is configured to control operation of said actuator to

15 move said coupling member between a coupled position in which said coupling member rotationally couples said input shaft to said steering shaft, and a decoupled position in which said input shaft is rotationally decoupled from said steering shaft.

30. The controller of claim 29, wherein the controller is further configured to

20 provide autonomous steering to said vehicle.

31. A method of controlling a steering system of a vehicle, said steering system comprising an input shaft, a steering shaft, and a coupling member arranged between said input shaft and said steering shaft, and wherein the method comprises the step of

25 moving the coupling member between a coupled position in which the coupling member rotationally couples the input shaft to the steering shaft, and a decoupled position in which the input shaft is rotationally decoupled from the steering shaft.

32. The method of claim 31, further comprising the steps of detecting the rotational position of the input shaft and the rotational position of the steering shaft, and rotationally aligning the input shaft and the steering shaft prior to moving the coupling

5 member from the decoupled position to the coupled position.

33. The method of claim 31 or claim 32, further comprising the step of moving the coupling member from the decoupled position to the coupled position when rotation of the input shaft is detected.

34. The method of any of claims 31 to 33, further comprising the step of moving the coupling member from the decoupled position to the coupled position when a user input is detected.

15 35· The method of any of claims 31 to 34, further comprising the step of autonomously steering said vehicle when the coupling member is in the decoupled position.

36. The method of claim 35, wherein the step of autonomously steering said vehicle 20 comprises controlling a steering motor arranged to rotate the steering shaft.

37. Apparatus comprising means for performing a method according to any of claims 31 to 36.

25 38. Computer-readable instructions which, when executed by computing apparatus, cause the computing apparatus to perform a method according to any of claims 31 to 36.