Steer-by-wire steering assembly

Abstract

A steer-by-wire steering assembly includes a motor assembly having at least one rotor and at least one stator and an electronic control unit. The steering assembly includes an actuator operatively coupled to the at least one rotor and a steering shaft connectable to the first pull rod and the second pull rod. The steering shaft is configured to engage with the actuator, and when the motor assembly is actuated, the steering shaft moves longitudinally relative to the housing. The steering shaft displacement sensor is configured to send a signal to the electronic control unit as a function of detecting a center reference target of the steering shaft. Wherein the electronic control unit is configured to determine a vehicle steady-state condition, and to determine a steering shaft offset from a signal received from the steering shaft displacement sensor when the vehicle is in the vehicle steady-state condition.

Description

Technical Field

[0001] The present disclosure relates to a steer-by-wire steering assembly. Background Art

[0002] One aspect of the required autonomous vehicle control is autonomous steering. Generally, the steering system required in an autonomous vehicle is a steer-by-wire steering system, which can be controlled by control signals from a vehicle control unit.

[0003] In the absence of user input, the vehicle systems of an autonomous vehicle need to be robust in order to make the autonomous vehicle reliable. This may mean that the steer-by-wire system has multiple redundancies to meet industry safety standards, such as Automotive Safety Integrity Level (ASIL) C or D of ISO 26262.

[0004] In order to be reliable enough for autonomous vehicles and associated legal requirements, the steer-by-wire system may need to be operable after a failure. This means that if the steer-by-wire system fails, the autonomous vehicle can still operate, even if the autonomous vehicle is operating at a reduced capacity.

[0005] In some cases, the steering system in a vehicle may be affected by the failure of other vehicle components, such as wheels. For example, a vehicle steering system shown in US2022017142 detects whether a vehicle has a lateral drift. The vehicle steering system issues a compensatory steering command based on the deviation of the steering position. The problem with this is that the lateral drift may be caused by an underlying problem, and if the vehicle continues to experience lateral drift, then compensating only for the lateral drift may pose a safety problem, where if the root cause is not detected and the root cause has an impact during the safe operation of the vehicle, the root cause may lead to further deterioration.

[0006] JP2022062982 detects an abnormality in tire pressure determined by abnormal steering torque and steering angle parameters of a steering system having a manual steering wheel. This means that the steering torque and steering angle are determined based on manual input from the user. Such a system is generally useless because the user may feel a lateral drift on the steering wheel due to low tire pressure. In addition, the system is not applicable to a steering system without a manually operated steering wheel. Summary of the Invention

[0007] Examples of the present disclosure are intended to solve the above problems.

[0008] In a first aspect of the present disclosure, a steer-by-wire steering assembly for a vehicle is provided. The steer-by-wire steering assembly includes: a housing; at least one electronic control unit; a motor assembly having at least one rotor and at least one stator, the at least one electronic control unit being configured to control the motor assembly; an actuator operatively coupled to the at least one rotor; a steering shaft connectable to a first tie rod and a second tie rod, the steering shaft being configured to engage with the actuator and longitudinally move relative to the housing when the motor assembly is actuated; and a steering shaft displacement sensor configured to send a signal to the at least one electronic control unit based on a detected reference target of the steering shaft, wherein the electronic control unit is configured to determine a vehicle steady state condition and, when the vehicle is in the vehicle steady state condition, determine a steering shaft offset based on the signal received from the steering shaft displacement sensor.

[0009] This means that the steer-by-wire steering assembly can utilize a displacement sensor that detects the relative position of the steering shaft to determine one or more faults in the vehicle's wheels or other components. For example, the steering shaft displacement sensor can detect the difference between the actual steering shaft position when the vehicle is traveling straight forward and the geometric center position of the steering shaft to detect low tire pressure. This means that this can provide additional sensor redundancy for determining tire pressure. In the case where the tire pressure sensor fails, the vehicle can still determine whether there is a fault condition in the wheel. This enables the steer-by-wire steering assembly to provide additional post-fault operable redundancy to other parts, subsystems, and systems of the vehicle.

[0010] By relying on the displacement sensor information of the steering shaft, the absolute position of the steering shaft is used to reliably determine fault conditions in the wheels, such as low pressure in the tires. This means that the displacement sensor information can be used in a post-fault operable system for the tire pressure sensor system. This means that the steer-by-wire steering assembly can determine fault conditions without relying on other intermediate systems.

[0011] Optionally, the reference target indicates the midpoint of the steering shaft, and when the steering shaft displacement sensor detects the center reference target, the midpoint of the steering shaft is aligned with the geometric center of the steering assembly.

[0012] Optionally, the at least one electronic control unit is configured to determine the displacement of the steering shaft based on the signal received from the steering shaft displacement sensor and the rotation information of the at least one rotor.

[0013] Optionally, the at least one electronic control unit is configured to receive an indication of the vehicle stable state or information for determining the vehicle steady state condition.

[0014] Optionally, at least one electronic control unit is configured to receive an indication of the vehicle's stable state or information for determining the vehicle's steady-state condition from a vehicle control unit, a vehicle motion controller, the vehicle's controller area network, a yaw rate sensor, at least one wheel speed sensor, or at least one body height sensor.

[0015] Optionally, the indication of the vehicle's stable state includes the vehicle's yaw rate and / or wheel speed.

[0016] Optionally, when the yaw rate is 0 radians per second or approximately 0 radians per second, at least one electronic control unit determines that the vehicle has a vehicle steady-state condition.

[0017] Optionally, at least one electronic control unit is configured to determine a steering fault condition based on determining that the steering axis is deflected when the vehicle is in a vehicle stable state.

[0018] Optionally, at least one electronic control unit is configured to determine a steering fault condition when the deflection of the steering axis exceeds a predetermined displacement.

[0019] Optionally, at least one electronic control unit is configured to determine a steering fault condition when the period during which the steering axis is deflected exceeds a predetermined period.

[0020] Optionally, at least one electronic control unit is configured to determine a steering fault condition when the relationship between the deflection and the vehicle's yaw rate exceeds a predetermined allowable variation.

[0021] Optionally, at least one electronic control unit is configured to determine that the deflection varies according to wheel rotation and / or with wheel speed.

[0022] Optionally, at least one electronic control unit is configured to determine whether the steering fault condition is one or more of a tire pressure fault, a chassis geometry fault, a wheel imbalance, or a wheel bearing fault.

[0023] Optionally, at least one electronic control unit is configured to receive a signal from a tire pressure sensor.

[0024] Optionally, at least one electronic control unit is configured to determine a tire leak condition based on the signal received from the tire pressure sensor and the steering fault condition.

[0025] Optionally, the actuator is a screw actuator configured to engage a threaded portion on the steering axis.

[0026] Optionally, the motor assembly includes a first motor and a second motor. The first motor has a first stator including a first motor winding, and the second motor has a second stator including a second motor winding. At least one rotor is shared by the first motor and the second motor.

[0027] Optionally, at least one electronic control unit is a first electronic control unit and a second electronic control unit, the first electronic control unit being configured to control a first motor winding and the second electronic control unit being configured to control a second motor winding.

[0028] Optionally, at least one electronic control unit is configured to receive a sensor signal from a tire pressure sensor or a tire pressure loss sensor.

[0029] Optionally, at least one electronic control unit is configured to determine a fault condition of the tire pressure sensor based on the determined vehicle steady state condition and a signal received from a steering shaft displacement sensor.

[0030] In a second aspect of the present disclosure, a method of controlling a steer-by-wire steering assembly for a vehicle is provided. The steer-by-wire steering assembly has: a housing; at least one electronic control unit; a motor assembly having at least one rotor and at least one stator, the at least one electronic control unit being configured to control the motor assembly; an actuator operatively coupled to the at least one rotor; and a steering shaft that can be connected to a first tie rod and a second tie rod, the steering shaft being configured to engage with the actuator and, when the motor assembly is actuated, move longitudinally relative to the housing. The method includes: detecting a reference target of the steering shaft using a steering shaft displacement sensor; sending a signal from the steering shaft displacement sensor to the at least one electronic control unit; determining a vehicle steady state condition; and when the vehicle is in a vehicle stable state, determining that a displacement of the steering shaft has deviated based on a signal received from the steering shaft displacement sensor.

[0031] In a third aspect of the present disclosure, a steer-by-wire steering assembly for a vehicle is provided. The steer-by-wire steering assembly includes: a housing; at least one electronic control unit; a motor assembly having at least one rotor and at least one stator, the at least one electronic control unit being configured to control the motor assembly; an actuator operatively coupled to the at least one rotor; a steering shaft that can be connected to a first tie rod and a second tie rod, the steering shaft being configured to engage with the actuator and, when the motor assembly is actuated, move longitudinally relative to the housing; and a steering shaft displacement sensor configured to send a signal to the at least one electronic control unit based on detecting a reference target of the steering shaft, wherein the electronic control unit is configured to determine a rotation of a wheel and determine that a displacement of the steering shaft has deviated based on a signal received from the steering shaft displacement sensor according to the rotation of the wheel.

[0032] Optionally, at least one electronic control unit is configured to determine the rotation of the wheel based on one or more of a wheel rotation sensor and an indication of wheel rotation.

[0033] Optionally, at least one electronic control unit is configured to determine that the change in the offset is a first-order response to the rotation of the wheel.

[0034] Optionally, at least one electronic control unit is configured to determine wheel imbalance.

[0035] In a fourth aspect of the present disclosure, a steer-by-wire steering assembly for a vehicle is provided, the steer-by-wire steering assembly including: a housing; at least one electronic control unit; a motor assembly having at least one rotor and at least one stator, the at least one electronic control unit being configured to control the motor assembly; an actuator operatively coupled to the at least one rotor; a steering shaft connectable to a first tie rod and a second tie rod, the steering shaft being configured to engage with the actuator and longitudinally move relative to the housing when a first motor winding and / or a second motor winding is actuated; a steering shaft displacement sensor configured to send a signal to the at least one electronic control unit based on detecting a reference target of the steering shaft; at least one tire pressure sensor or tire pressure loss sensor configured to generate a pressure signal of a wheel mounted to the first tie rod or the second tie rod, wherein the electronic control unit is configured to determine a vehicle steady state condition, determine a steering shaft offset based on a signal received from the steering shaft displacement sensor, and determine a fault condition of the at least one tire pressure sensor based on the determined vehicle steady state condition and the determined steering shaft offset. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In the following detailed description with reference to the accompanying drawings and the appended claims, various other aspects and other examples are also described, in which:

[0037] Figure 1 A perspective view of a steering assembly according to an example is shown;

[0038] Figure 2 A side cross-sectional view of a steering assembly according to an example is shown;

[0039] Figure 3 A partial perspective view of a steering assembly according to an example is shown;

[0040] Figure 4 A side cross-sectional view of a steering assembly according to an example is shown;

[0041] Figure 5a and Figure 5b A schematic front view of a steering assembly with different vehicle conditions according to an example is shown;

[0042] Figure 6 is shown as Figure 5b A schematic close-up front view of the steering assembly shown is shown;

[0043] Figure 7 shows a schematic representation of a steering assembly according to an example;

[0044] Figure 8 shows a flowchart of the operation of a steering assembly according to an example;

[0045] Figure 9 shows a graph of the parameters of a steering assembly during operation according to an example. DETAILED DESCRIPTION

[0046] Figure 1 shows a perspective view of the steering assembly 100. The steering assembly 100 includes a main housing 102, and one or more components of the steering assembly 100 are mounted within the main housing 102. Structurally, the steering assembly 100 is generally elongated and extends along a longitudinal axis A-A. As discussed below, one or more components of the steering assembly 100 are aligned along the longitudinal axis A-A.

[0047] As Figure 1 shown, the steering assembly 100 is coupled to a first tie rod 104 at a first steering assembly end 106 of the steering assembly 100. The steering assembly 100 is also coupled to a second tie rod 108 at a second steering assembly end 110 of the steering assembly 100.

[0048] The steering assembly 100 is coupled to the first tie rod 104 using a first tie rod coupler 300 (best shown in Figure 3 ). Figure 3 shows a partial perspective view of the steering assembly 100 at the first steering assembly end 106. The steering assembly 100 is also coupled to the second tie rod 108 using a second tie rod coupler (not shown). In some examples, both the first tie rod coupler 300 and the second tie rod coupler are ball joints.

[0049] The steering assembly 100 includes a steering shaft 200 (best shown in Figure 2 ). Figure 2 shows a side cross-sectional view of the steering assembly 100. The steering shaft 200 is configured to move relative to the main housing 102 in a linear direction along the longitudinal axis A-A. In some examples, the longitudinal axis of the steering shaft 200 is aligned with the longitudinal axis A-A of the steering assembly 100, e.g., coaxial with the longitudinal axis A-A of the steering assembly 100. In some other examples, the longitudinal axis of the steering shaft 200 extends in a direction parallel to the longitudinal axis A-A of the steering assembly 100.

[0050] The first tie rod 104 and the second tie rod 108 are respectively connected to a first tie rod end 116 and a second tie rod end 118. The first tie rod end 116 and the second tie rod end 118 are configured to be pivotally connected to a first steering knuckle 500 and a second steering knuckle 502 respectively. For example, the first steering knuckle 500 and the second steering knuckle 502 can be spherical joints (as schematically shown in Figure 5a ). The first tie rod 104 and the second tie rod 108, and the first steering knuckle 500 and the second steering knuckle 502 are known and will not be discussed in any further detail.

[0051] As Figure 1 shown, in some examples, the main housing 102 includes a plurality of different housing portions having different diameters. In some examples, the different housing portions are separate elements and can be mounted to each other. This can make the assembly during manufacturing easier. For example, the ECU housing 206 is mounted to the main housing 102. The main housing 102 can be mounted to a vehicle structure (not shown), such as a chassis, by a first mounting connection member 130 and a second mounting connection member 132.

[0052] In some examples, the vehicle is an electric vehicle, such as an electric car or an electric truck. In some other examples, the vehicle is a vehicle with an internal combustion engine or any other type of motor vehicle. The steering assembly 100 discussed with reference to the accompanying drawings can optionally be used with any suitable vehicle having at least one steerable wheel.

[0053] In some examples, the steering assembly 100 is a steer-by-wire steering assembly 100. The term "steer-by-wire" means that there is no mechanical coupling between the user input (such as a steering wheel (not shown) or a control input device) and the steering assembly 100. For example, the steering assembly 100 does not include a steering wheel connected to a rack and pinion mechanism (not shown).

[0054] Alternatively, control instructions are provided from one or more electronic control units (ECUs) 202, 204 configured to control the steering assembly 100. As mentioned above, the first ECU 202 and the second ECU 204 are mounted in the ECU housing 206. The ECU housing 206 is mounted to the main housing 102. In some other examples, the ECU housing 206 is mounted at a position separate from the steering assembly 100, or mounted away from the main housing 102 and connected to the steering assembly 100 through data and power connections, as shown. The first ECU 202 and the second ECU 204 are optionally from a vehicle control unit (VCU) 700 (in Figure 7receives control instructions optimally shown in (or receives control instructions from another device connected to the controller area network (CAN) bus 702 of the vehicle). In some examples, the VCU 700 can be a vehicle motion controller (VMC). The data connections to the first ECU 202, the second ECU 204, the CAN bus 702, and the data connections from the first ECU 202 and the second ECU 204 to the CAN bus 702 are shown in Figure 7 In some less preferred examples, the steering assembly 100 is optionally configured to receive control instructions directly from the VCU 700, and there is no ECU 202, ECU 204.

[0055] Hereinafter, the term "steering assembly 100" will be used to refer to the steer-by-wire steering assembly 100.

[0056] In some examples, the steering assembly 100 is controlled in response to control instructions from a user input (e.g., an electrically connected steering wheel). Alternatively, other user input devices (e.g., a joystick or any other suitable user input control device) can be used with the steering assembly 100.

[0057] Additionally or alternatively, the steering assembly 100 is controlled according to control instructions received from the first ECU 202 or the second ECU 204 or the VCU 700. For example, the steering assembly 100 is optionally a sub-component of an autonomous vehicle. However, even if the steering assembly 100 is used in an autonomous vehicle, it is preferably allowed to control the steer-by-wire steering assembly 100 according to a user input device (e.g., an electrically connected steering wheel). This will allow for user control testing and inspection of the steering assembly 100 in an autonomous vehicle on the road.

[0058] Turning to Figure 2 , the steering assembly 100 will be discussed in more detail.

[0059] The steering assembly 100 includes a motor assembly 250 having a first motor 208 and a second motor 210. The first motor 208 and the second motor 210 are mounted within the motor housing portion 120. In some examples, the first motor 208 is controlled by the first ECU 202, and the second motor 210 is controlled by the second ECU 204.

[0060] Additionally or alternatively, the first electric machine 208 and / or the second electric machine 210 are configured to receive control instructions from any one of the first ECU 202, the second ECU 204, or the VCU 700. Hereinafter, the control of the steering assembly 100 is described with reference to the first ECU 202 and the second ECU 204 issuing control instructions to the first electric machine 208 and the second electric machine 210. The first ECU 202 is configured to issue control instructions to the first electric machine 208 and / or the second electric machine 210. Similarly, the second ECU 204 is configured to issue control instructions to the first electric machine 208 and / or the second electric machine 210. The first ECU 202 and the second ECU 204 can operate independently of each other, or alternatively, can operate together. This means that the control functions discussed herein for the first ECU 202 also apply to the second ECU 204.

[0061] In some preferred examples, the first ECU 202 is configured to control the first electric machine 208, and the second ECU 204 is configured to control the second electric machine 210. The first ECU 202 and the second ECU 204 are connected to the ECU data connection 702 (as Figure 7 shown) and are configured to communicate their operating states to each other via the ECU data connection 702. Alternatively, the communication between the first ECU 202 and the second ECU 204 is carried out via the CAN bus 702. The first ECU 202 and the second ECU 204 are configured to send fault states to the other ECU 202, 204 and / or the VCU 700, and to receive fault states from the other ECU 202, 204 and / or the VCU 700. In this way, the first ECU 202 can determine whether there is a fault condition in the second ECU 204 or the second electric machine 210 based on the system status message sent from the second ECU 204. Similarly, the second ECU 204 can determine whether there is a fault condition in the first ECU 202 or the first electric machine 208 based on the system status message sent from the first ECU 202. Hereinafter, the CAN bus 702 is referred to, but any suitable data connection (including wireless data connection or wired data connection) can be used between the first ECU 202 and the second ECU 204 and other components of the vehicle (such as the VCU 700, the steering shaft displacement sensor 306, the tire pressure sensor 706, etc.).

[0062] In the event that, for example, the second ECU 204 or the second electric machine 210 experiences a fault or malfunction, the second ECU 204 sends a system status message including a fault indication to the first ECU 202, or does not send a system status message. When receiving a system status message including a fault indication, or when the first ECU 202 determines that no system status message has been received, the first ECU 202 determines that the second ECU 204 or the second electric machine 210 has a fault or malfunction. Accordingly, the first ECU 202 assumes full control of the steering assembly 100, and the first ECU 202 issues a control command to the first electric machine 208. In this way, when the second ECU 204 or the second electric machine 210 fails, the first ECU 202 and the first electric machine 208 can still operate the steering assembly 100. The second ECU 204 includes functions similar to those of the first ECU 202 and is configured to assume full control of the steering assembly 100 if the second ECU 204 determines that the first ECU 202 or the first electric machine 208 has failed.

[0063] One or all of the first ECU 202, the second ECU 204, and / or the VCU 700 may be implemented at least in part by software executed by a processing unit. The first ECU 202, the second ECU 204, and / or the VCU 700 may be configured as separate units, or the first ECU 202, the second ECU 204, and / or the VCU 700 may be incorporated into a single unit. One or all of the first ECU 202, the second ECU 204, and / or the VCU 700 may be implemented at least in part by software executed by a processing unit.

[0064] The processing unit of the first ECU 202, the second ECU 204, and / or the VCU 700 may be implemented by dedicated software (or firmware) running on one or more general-purpose or special-purpose computing devices. In context, it should be understood that each "element" or "device" of such a computing device refers to the conceptual equivalent of a method step; there does not always exist a one-to-one correspondence between an element / device and a particular piece of hardware or software routine. One piece of hardware sometimes includes different devices / elements. For example, when executing one instruction, the processing unit may act as one element / device, but when executing another instruction, the processing unit may act as another element / device. Additionally, in some cases, one element / device may be implemented by one instruction, but in some other cases, one element / device may be implemented by multiple instructions. Naturally, it is conceivable that one or more elements (devices) are implemented entirely by analog hardware components.

[0065] The processing unit may include one or more processing units, such as a CPU (“Central Processing Unit”), a DSP (“Digital Signal Processor”), an ASIC (“Application Specific Integrated Circuit”), discrete analog and / or digital components, or some other programmable logic device such as an FPGA (“Field Programmable Gate Array”). The processing unit may also include a system memory and a system bus that couples various system components, including the system memory, to the processing unit. The system bus can be any of several types of bus structures, including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. The system memory may include computer storage media in the form of volatile and / or non-volatile memory, such as read only memory (ROM), random access memory (RAM), and flash memory. The dedicated software and associated control parameter values may be stored in the system memory or on other removable / non-removable volatile / non-volatile computer storage media (such as magnetic media, optical media, flash memory cards, digital tapes, solid state RAM, solid state ROM, etc.) included in or accessible to the computing device. The processing unit may include one or more communication interfaces (such as serial interfaces, parallel interfaces, USB interfaces, wireless interfaces, network adapters, etc.) and one or more data acquisition devices (such as A / D converters). The dedicated software can be provided to the processing unit on any suitable computer readable medium (including a recording medium and read only memory).

[0066] The first electric machine 208 includes a first stator 212 and a first rotor 214. The term “electric machine” means a set of electric machine windings disposed in a stator that are configured to rotate at least one rotor when energized. The first stator 212 includes one or more electric machine windings that are configured to rotate the first rotor 214 when energized. The first rotor 214 is mounted on a rotor support sleeve 216 that is configured to rotate when the first rotor 214 rotates. The first rotor 214 is fixed relative to the rotor support sleeve 216. In some examples, the first rotor 214 is press fit onto the rotor support sleeve 216. In some alternative examples, a tolerance ring (not shown) is used instead of a press fit. A tolerance ring can be beneficial because it is easier to install a tolerance ring with less force, which reduces the risk of damage to the surface of the rotor support sleeve 216 during assembly.

[0067] The second motor 210 includes a second stator 218 and a second rotor 220. The second stator 218 includes one or more motor windings configured to rotate the second rotor 220 when energized. The second rotor 220 is also mounted on a rotor support sleeve 216 configured to rotate when the second rotor 220 rotates. The second rotor 220 is also fixed relative to the rotor support sleeve 216. In some examples, similarly, the second rotor 220 is press-fitted onto the rotor support sleeve 216.

[0068] In some other examples, the motor assembly 250 includes only the first stator 212, which includes a first set of motor windings and a second set of motor windings. The first stator 212 having the first set of motor windings and the second set of motor windings is configured to rotate the first rotor 214 when the first set of motor windings or the second set of motor windings is energized. In this example, there is only a single first rotor 214. In fact, the first set of motor windings or the second set of motor windings is configured to rotate the first rotor 214 when energized. In this example, the first motor 208 can be considered a combination of the first stator 212 having the first set of motor windings and the first rotor 214. The second motor 210 can be considered a combination of the first stator 212 having the second set of motor windings and the first rotor 214.

[0069] In another example, the first motor 208 and the second motor 210 each include a first stator 212 and a second stator 218, but the first motor 208 and the second motor 210 share a common first rotor 214. In this case, the first rotor 214 is shared by the first motor 208 and the second motor 210. Accordingly, the first motor 208 can be considered a combination of the first stator 212 having the first set of motor windings and the first rotor 214. The second motor 210 can be considered a combination of the second stator 218 having the second set of motor windings and the first rotor 214.

[0070] In another example, the motor assembly 250 includes a first stator 212, which includes a first set of motor windings and a second set of motor windings combined with the first rotor 214 and the second rotor 220. The first stator 212 having the first set of motor windings is configured to rotate the first rotor 214 when energized. The first stator 212 having the second set of motor windings is configured to rotate the second rotor 220 when energized. In this example, the first motor 208 can be considered a combination of the first stator 212 having the first set of motor windings and the first rotor 214. The second motor 210 can be considered a combination of the first stator 212 having the second set of motor windings and the second rotor 220.

[0071] In other examples, the first motor 208 and the second motor 210 can have any suitable number of sets of motor windings, such as two sets, three sets, four sets of motor windings with multiple phases (e.g., 3 or 6 phases), etc.

[0072] It should be noted that the variations in the motor assembly 250, the first motor 208 and the second motor 210 discussed previously, and the arrangements of the first stator 212, the second stator 218, the first rotor 214 and the second rotor 220 apply to any example discussed with reference to the accompanying drawings.

[0073] In some examples, the first motor 208 and the second motor 210 are induction motors. In some other examples, the first motor 208 and the second motor 210 are any other suitable type of motor, such as a brushless DC motor (BLDC), a synchronous motor, a three-phase induction motor, etc.

[0074] Now, a preferred example as Figure 2 shown will be discussed in more detail. That is, the first motor 208 includes a first stator 212 and a first rotor 214, and the second motor 210 includes a second stator 218 and a second rotor 220.

[0075] In this way, the second motor 210 or the first motor 208 is configured to rotate the rotor support sleeve 216. Accordingly, the second motor 210 or the first motor 208 is configured to provide torque and speed to the rotor support sleeve 216. For example, if one of the first motor 208 and the second motor 210 fails, the other of the first motor 208 and the second motor 210 can still rotate the rotor support sleeve 216. "Failure" means any matter related to the operation of the ECU, sensors or motors 208, 210. For example, the second ECU 204, the second motor 210 or one or more sensors fail. Then, a part of the steering assembly 100 including the second ECU 204 and the second motor 210 shuts down, and the first ECU 202 is configured to provide functions by sending control instructions to the first motor 208. This means that the steering assembly 100 is operable even if one of the first motor 208 and the second motor 210 is inoperable. Therefore, this provides redundancy that is operable after a failure.

[0076] Although Figure 2 the first motor 208 and the second motor 210 in the steering assembly 100 are shown, in other examples, any suitable number of motors can be installed within the motor housing portion 120. Additionally, as previously mentioned, there can be multiple motor windings. This means that in some examples, there can be one physical motor, but multiple separate motor circuits provide separate motor functions. For example, there can be three motors, four motors, etc. As Figure 2The first motor 208 and the second motor 210 shown are adjacent to each other within the motor housing portion 120.

[0077] The rotor support sleeve 216 is an elongated tube extending along the longitudinal axis A-A. The rotor support sleeve 216 is rotatable about the steering shaft 200. The rotor support sleeve 216 is coaxial with the steering shaft 200. The first sleeve end 222 of the rotor support sleeve 216 is rotatably mounted to the main housing 102 by a rotor support sleeve bearing 224.

[0078] The second sleeve end 226 of the rotor support sleeve 216 is connected to a screw actuator 228. The screw actuator 228 is mounted in the main housing 102. Similar to the rotor support sleeve bearing 224, the screw actuator 228 is press-fitted into the main housing 102. The screw actuator 228 is configured to engage with the threaded portion 1000 of the steering shaft 200.

[0079] When the screw actuator 228 rotates, the screw actuator 228 is configured to cause the steering shaft 200 to linearly displace along the longitudinal axis A-A. Depending on the rotation direction of the screw actuator 228, the steering shaft 200 moves in the direction towards the first steering component end 106 or in the direction towards the second steering component end 110. Accordingly, the torque, direction, and speed of rotation of the first motor 208 and / or the second motor 210 determine the speed, direction, and magnitude of the linear displacement of the steering shaft 200.

[0080] As Figure 2 shown, in some examples, the screw actuator 228 is a planetary roller screw 230. In some other examples, the screw actuator 228 is a ball screw bearing (not shown) configured to engage with the threaded portion 1000. In some other examples, the screw actuator 228 is any suitable rotary mechanism configured to engage with one or more portions of the groove of the threaded portion 1000 while rotating. In Figure 2 it, there is an integrated roller screw 230 having a rotating nut and bearing. However, in some other examples, there may be a separate roller screw and nut pressed into the bearing.

[0081] To enable the first ECU 202 and the second ECU 204 to determine the state of one or more components of the steering assembly 100, the steering assembly 100 includes at least one steering shaft displacement sensor 306 connected to the first ECU 202 and the second ECU 204. The steering shaft displacement sensor 306 is configured to generate a signal and send the signal to the first ECU 202 and / or the second ECU 204. The first ECU 202 and / or the second ECU 204 is configured to determine the linear displacement of the steering shaft 200 relative to the main housing 102 based on the signal received from the steering shaft displacement sensor 306.

[0082] Now, the steering shaft displacement sensor 306 will be described in more detail with reference to Figure 3 and Figure 4 More specifically, the steering shaft displacement sensor 306 will be described in more detail with reference to FIGS. Figure 3 A partial perspective view of the steering assembly 100 at the first steering assembly end 106 is shown. Figure 4 A close-up side cross-sectional view of the steering assembly 100 is shown.

[0083] As Figure 3 shown, the first steering assembly end 106 of the main housing 102 includes the steering shaft displacement sensor 306. In some examples, the steering shaft displacement sensor 306 is a cross-center sensor 306. That is, the steering shaft displacement sensor 306 is configured to detect the movement of the center reference target 400 relative to the geometric center C of the steering assembly 100. For example, when the steering shaft 200 moves from the center-aligned position, the steering shaft displacement sensor 306 detects the movement of the steering shaft 200. The steering shaft displacement sensor 306 is mounted in the first housing sleeve portion 304.

[0084] The steering shaft displacement sensor 306 will be described in more detail in Figure 3 The steering shaft displacement sensor 306 will be described in more detail in Figure 3 A first steering shaft bearing 302 is shown including an elongated channel 310. The first steering shaft bearing 302 may include a single construction or may include multiple bearing parts. The elongated channel 310 in the first steering shaft bearing 302 enables the steering shaft displacement sensor 306 to access the steering shaft 200. Alternatively, the steering shaft displacement sensor 306 may be mounted at a different location on the main housing 102 such that the steering shaft displacement sensor 306 does not project through the elongated channel 310 of the first steering shaft bearing 302. In all examples, the steering shaft displacement sensor 306 is fixed relative to the main housing 102. This means that the steering shaft displacement sensor 306 is configured to detect the relative movement of the steering shaft 200 relative to the main housing 102.

[0085] In some examples, the steering shaft displacement sensor 306 is configured to generate a sensor signal based on the absolute position information of the steering shaft 200 relative to the main housing 102. The steering shaft displacement sensor 306 is configured to detect the center reference target 400. Specifically, the steering shaft displacement sensor 306 is configured to detect the center reference target 400 when the midpoint 260 of the steering shaft 200 is aligned with the geometric center C of the steering assembly 100. Figure 2 A midpoint 260 of the steering shaft 200 is shown aligned with the geometric center C of the steering assembly 100. This means that when the midpoint 260 of the steering shaft 200 is aligned with the geometric center C of the steering assembly 100, the steering assembly 100 is in the "straight ahead" position. In normal operation, the wheels mounted on the steering assembly 100 will have a zero steering angle and be in the straight ahead position. This is shown inFigure 5a is schematically shown.

[0086] Figure 4 A schematic representation of a steering shaft displacement sensor 306 located above the steering shaft 200 is shown. The steering shaft displacement sensor 306 is configured to detect a center reference target 400. As previously mentioned, the center reference target 400 is not the midpoint 260 of the steering shaft 200. Figure 4 The center reference target 400 in [[ ]] is optionally a tooth or a reference notch 402 protruding from the steering shaft 200, and the tooth or the reference notch 402 is aligned with the center reference target 400.

[0087] As Figure 3 shown, the steering shaft displacement sensor 306 is mounted on a first housing sleeve portion 304 at a first steering assembly end 106 of the main housing 102. As Figure 3 shown, the steering shaft displacement sensor 306 is not located above the geometric center C of the steering assembly 100. In some less preferred examples, the steering shaft displacement sensor 306 is mounted above the geometric center C of the steering assembly 100. However, in more preferred examples, the steering shaft displacement sensor 306 is mounted away from the geometric center C, which provides more space for other components of the steering assembly 100. This means that heavier components (such as the first motor 208 and the second motor 210) of the steering assembly 100 are mounted at the center of the steering assembly 100. This contributes to the stability of the vehicle equipped with the steering assembly 100.

[0088] The steering shaft displacement sensor 306 is configured to generate an axis center signal when the center reference target 400 moves past the steering shaft displacement sensor 306. In some examples, the center reference target 400 is a magnet, a reference notch 402 or a recess in the steering shaft 200, or a protruding stud protruding from the steering shaft 200. In some examples, the steering shaft displacement sensor 306 is a Hall effect sensor, which is configured to detect, for example, a magnet, a reference notch 402 or a recess in the steering shaft 200, or a protruding stud protruding from the steering shaft 200.

[0089] Although the example shown in the figure shows a Hall effect sensor, in other examples, the steering shaft displacement sensor 306 can be any other suitable sensor. For example, the steering shaft displacement sensor 306 can be an optical sensor configured to detect a center reference indication mark on the steering shaft 200. In some other examples, the center reference target 400 includes a projection finger (not shown), and the steering shaft displacement sensor 306 is a mechanical switch, a pressure sensor or a force sensor, which is configured to generate an axis center signal when the projection finger moves past the center reference target 400, for example, actuating the mechanical switch.

[0090] Reference Figure 3 The steering shaft displacement sensor 306 shown and described is a simple way to determine the absolute position of the steering shaft 200 relative to the steering assembly 100.

[0091] Figure 3 A specific implementation of the steering shaft displacement sensor 306 is shown. In some other examples, the displacement of the steering shaft 200 can be determined by the first ECU 202 or the second ECU 204 using any other type of sensor suitable for detecting the linear displacement of the steering shaft 200 relative to the main housing 102. For example, the first ECU 202 or the second ECU 204 can receive signals from a rotational sensor corresponding to the rotational movement of the first rotor 214 or the second rotor 220. Then, the first ECU 202 or the second ECU 204 can determine the linear displacement of the steering shaft 200 based on the rotational signals (e.g., the speed and direction of the first rotor 214 or the second rotor 220) and the stored parameters of the steering shaft 200 (e.g., the gear ratio of the screw actuator 228).

[0092] Optionally, as Figure 3 shown, the steering shaft displacement sensor 306 can be configured to additionally detect a plurality of reference notches 402 on the steering shaft 200. The plurality of reference notches 402 form a linear tooth pattern 414 on the steering shaft 200. When each reference notch 402 passes by the steering shaft displacement sensor 306, the steering shaft displacement sensor 306 is configured to generate a center axis signal and send the center axis signal to the first ECU 202 or the second ECU 204. Then, the first ECU 202 or the second ECU 204 can also determine the distance by which the steering shaft 200 has moved from the geometric center C of the steering assembly 100.

[0093] In some examples, the steering shaft displacement sensor 306 is configured to vary the generated signal based on the position of the steering shaft displacement sensor 306 relative to the linear tooth pattern 414. For example, the spacing and size of the notches vary along the length of the linear tooth pattern 414.

[0094] The linear tooth pattern 414 includes different patterns directly around the central reference target 400. The linear tooth pattern 414 includes primary adjacent reference targets 406, 408 positioned on either side of the central reference target 400. The distance between the primary adjacent reference targets 406, 408 and the central reference target 400 is greater than the spacing between other targets 410, 412. This means that the central reference target 400 is configured to generate a unique axis center signal in the vicinity of the central reference target 400 based on the position of the steering shaft 200 relative to the main housing 102.

[0095] Accordingly, the steering shaft displacement sensor 306 is configured to generate a shaft center signal when the center reference target 400 moves in either direction (as indicated by arrow 404) along the longitudinal axis A-A.

[0096] As mentioned above, when the steering assembly 100 is in the straight-ahead position, the first ECU 202 or the second ECU 204 receives a shaft center signal indicating that the midpoint 260 of the steering shaft 200 is centered. Then, when the shaft center signal is received, the first ECU 202 or the second ECU 204 determines that the linear displacement of the steering shaft 200 is zero. This means that the first ECU 202 or the second ECU 204 does know that the steering shaft 200 is centered.

[0097] Meanwhile, the first ECU 202 or the second ECU 204 is optionally configured to determine rotational signal information, for example, from signals received from the rotational sensor 240. The rotational sensor 240 is configured to detect the rotational movement of one or more rotational components of the steering assembly 100 (such as the first motor 208 and / or the second motor 210, etc.). Accordingly, the first ECU 202 or the second ECU 204 determines the rotational displacement of one or more rotational components of the steering assembly 100. By combining the signals received from the steering shaft displacement sensor 306 with the rotational information of the motor assembly 250, the first ECU 202 or the second ECU 204 can determine the magnitude of the linear displacement of the steering shaft 200.

[0098] The first ECU 202 or the second ECU 204 can optionally receive rotational information from the first motor 208 or the second motor 210. For example, the first motor 208 and the second motor 210 include data connections leading to the first ECU 202 or the second ECU 204, and the first ECU 202 or the second ECU 204 receives the status information of the first motor 208 and the second motor 210. Additionally or alternatively, the first ECU 202 or the second ECU 204 receives rotational information from at least one rotational sensor 240.

[0099] In some other examples, the first ECU 202 or the second ECU 204 does not receive rotational information from the first motor 208 and the second motor 210 or at least one rotational sensor 240. Instead, the first ECU 202 or the second ECU 204 determines the rotational information of the first motor 208 and the second motor 210 based on the control instructions sent to the first motor 208 and the second motor 210.

[0100] Then, the first ECU 202 or the second ECU 204 receives the steering component parameters. The reception of the steering component parameters may include obtaining the parameters of the steering component 100 from the memory. For example, the steering component parameters are stored in a look-up table in the memory. The steering component parameter is the transmission coefficient of the screw actuator 228. The transmission coefficient of the screw actuator 228 determines how far the steering shaft 200 moves relative to the main housing 102 during each full rotation of the first motor 208 or the second motor 210.

[0101] The first ECU 202 or the second ECU 204 determines the linear displacement of the steering shaft 200 based on the steering component parameters and the determined rotation signal information. For example, the first ECU 202 or the second ECU 204 multiplies the number of rotations of the first motor 208 or the second motor 210 by the transmission coefficient to determine the linear displacement of the steering shaft 200.

[0102] The first ECU 202 or the second ECU 204 continuously monitors and determines the linear displacement of the steering shaft 200. As mentioned above, the first ECU 202 or the second ECU 204 periodically receives the shaft center signal from the steering shaft displacement sensor 306.

[0103] In some scenarios, other components of the vehicle may affect the steering component 100. This means that the steer-by-wire steering component 100 can use the steering shaft displacement sensor 306 to detect the relative position of the steering shaft 200 to determine one or more faults of the vehicle's wheels or other components. For example, the steering shaft displacement sensor 306 detects the displacement of the midpoint 260 of the steering shaft 200 relative to the geometric center C of the steering component 100, which can be used to determine the fault condition of the wheel, such as low tire pressure. This means that the steering component 100 can provide additional sensor redundancy for determining tire pressure. In the case where the tire pressure sensor 706 fails, the vehicle can still determine the existence of a fault condition of the wheel. This enables the steer-by-wire steering component 100 to provide additional post-fault operable redundancy to other parts of the vehicle.

[0104] Figure 5a A schematic representation of the steering component 100 operating under normal conditions is shown. Figure 5a The first wheel 504 connected to the first tie rod 104 and the second wheel 506 connected to the second tie rod 108 are shown. The first steering knuckle 500 and the second steering knuckle 502 are schematically represented. The first wheel 504 and the second wheel 506 are inflated to the correct tire pressure, and there is no fault condition of the vehicle. During normal operation, the first wheel 504 and the second wheel 506 rotate about the first rotation axis B-B. Figure 5a The longitudinal axis A-A of the steering component 100 is also shown for comparison.

[0105] Figure 5b Shows a representation of the steering assembly 100 when a fault scenario occurs. Here, the first wheel 504 has a low tire pressure because, for example, the first wheel 504 has a puncture. This means that the second wheel 506 still rotates about the first axis of rotation B-B, but the first wheel 504 now rotates about the second axis of rotation B'-B'. The second axis of rotation B'-B' is at a lower height than the first axis of rotation B-B because the tire wall of the first wheel 504 is lower due to the low tire pressure. Accordingly, the second axis of rotation B'-B' is lower than the first axis of rotation B-B by a height H1.

[0106] Since the first wheel 504 now rotates about the second axis of rotation B'-B', as Figure 6 shown, the first tie rod 104 also moves downward by the height H1. Accordingly, the lateral positions of the first tie rod 104 and the steering shaft 200 relative to the main housing 102 also change. As Figure 6 shown, the lateral position of the steering shaft 200 moves a distance D. This means that the midpoint 260 of the steering shaft 200 will deviate from the geometric center C of the steering assembly 100 by the distance D. This means that the steering assembly 100 and the vehicle experience lateral drift due to a flat tire.

[0107] In the case where the first wheel 504 has an under-inflated tire, the effective horizontal vector of the length of the first tie rod 104 is reduced. The positions of the first wheel 504 and the second wheel 506 are fixed with respect to the kingpin axis, and there is a shorter effective total steering length between the first wheel 504 and the second wheel 506. This causes the steering assembly 100 to generate a steering angle on the first wheel 504 and the second wheel 506. If the vehicle includes a Castor or Ackerman steering geometry, then this would mean that the imbalance acts equally between the first wheel 504 and the second wheel 506 and generates a steering effect, such as the steering assembly 100 experiencing steering drift. This means that steering correction is required in the steering assembly 100 to correct this steering effect to maintain the vehicle in a straight-ahead position. In other words, when in the straight-ahead position, this can create an offset between the geometric center C of the steering assembly 100 and the midpoint 260 of the steering shaft 200.

[0108] Now, a method for the steering assembly 100 to detect a fault condition will be discussed with reference to Figure 8 which shows a flowchart.

[0109] During normal operation, the first ECU 202 and / or the second ECU 204 are configured to receive a shaft center signal from the steering shaft displacement sensor 306, as shown in step 800. Then, in step 802, the first ECU 202 and / or the second ECU 204 determine that the steering shaft 200 is centered. The first ECU 202 and / or the second ECU 204 do know that the midpoint 260 of the steering shaft 200 is aligned with the geometric center C of the steering assembly 100. This process repeats, and as the vehicle moves and steers, the first ECU 202 and / or the second ECU 204 will periodically determine that the steering shaft 200 is centered. Between subsequently received shaft center signals, the first ECU 202 and / or the second ECU 204 may optionally determine the magnitude of the displacement based on the rotational information of the lead screw actuator 228 as mentioned above, as shown in step 804.

[0110] Although the previous examples disclose that the first ECU 202 and / or the second ECU 204 receive signals indicating the yaw angular velocity of the vehicle, in some other examples, the first ECU 202 and / or the second ECU 204 do not receive an indication of the yaw angular velocity. Instead, the first ECU 202 and / or the second ECU 204 determine whether the vehicle is in a steady-state condition based on other information, such as whether it is in a straight-ahead position. In some examples, when the command from the VCU 700 remains unchanged for a predetermined period of time, the first ECU 202 and / or the second ECU 204 determine that the vehicle is moving in a straight-ahead direction. In some examples, the predetermined period of time is 1 s, 2 s, 3 s, 4 s, 5 s, or any other suitable period of time. Since the vehicle will not travel with a constant steering angle for more than a few seconds, if no request for the steering angle is received after the predetermined period of time, the first ECU 202 and / or the second ECU 204 determine the straight-ahead position. Accordingly, the first ECU 202 and / or the second ECU 204 can determine when the vehicle is in a steady-state condition (e.g., straight-ahead position) and determine the offset between the geometric center and the actual steering shaft position without the yaw angular velocity data of the vehicle.

[0111] In step 806, the first ECU 202 and / or the second ECU 204 receive a steering position request. The steering position request is received from the VCU 700 or the VMC. The steering position request is an instruction for the steering angle required by the first ECU 202 or the second ECU 204 for the steering assembly 100. When the first ECU 202 or the second ECU 204 receives a steering position request in step 806, the first ECU 202 or the second ECU 204 also optionally performs a condition check of the steering assembly 100 to detect whether a fault condition of the steering assembly 100 or the first wheel 504 and the second wheel 506 has occurred.

[0112] When receiving a steering position request from, for example, the VCU 700, the first ECU 202 and the second ECU 204 may automatically perform steps to check for a fault condition. This means that the first ECU 202 and the second ECU 204 continuously check for a fault condition. Alternatively or additionally, the first ECU 202 and the second ECU 204 may receive a control instruction (e.g., from the VCU 700) from the CAN bus 702 that the first ECU 202 and the second ECU 204 must perform a check for a fault condition. In this case, the VCU 700 may request that the first ECU 202 or the second ECU 204 check for a fault condition. This may be because the VCU 700 wants to confirm whether there is a fault condition.

[0113] When the first ECU 202 or the second ECU 204 receives a steering position request, the first ECU 202 or the second ECU 204 performs the steering position request by actuating the first motor 208 or the second motor 210, as shown in step 808. The first ECU 202 or the second ECU 204 controls the first motor 208 and the second motor 210 to move the steering shaft 200, as discussed above. This causes the first wheel 504 and the second wheel 506 to steer to the desired steering angle. Step 808 may optionally be performed after or before steps 810, 812.

[0114] In step 810, the first ECU 202 or the second ECU 204 receives an indication of the yaw rate of the vehicle. The yaw rate is the speed at which the vehicle rotates about the vertical axis of the vehicle. The yaw rate is received by the first ECU 202 or the second ECU 204 from the CAN bus 702. The yaw rate may be broadcast on the CAN bus 702 with a timestamp, and the first ECU 202 or the second ECU 204 may read the data. In some examples, the yaw rate is broadcast on the CAN bus 702 in degrees per second or radians per second.

[0115] Optionally, in step 810, the first ECU 202 or the second ECU 204 may also receive additional information related to the operation of the vehicle. For example, the first ECU 202 or the second ECU 204 optionally receives the wheel rotation speed via the CAN bus 702. Optionally, the first ECU 202 or the second ECU 204 may also receive a pressure signal from the tire pressure sensor 706, for example, via the CAN bus 702.

[0116] In step 812, the first ECU 202 or the second ECU 204 determines that the vehicle is in a vehicle steady state condition based on the yaw rate. In most examples, when the yaw rate is 0 degrees per second, the first ECU 202 or the second ECU 204 determines that the vehicle is in a vehicle steady state condition. In this case, the first ECU 202 or the second ECU 204 determines that the vehicle steady state condition is the "going straight forward" position.

[0117] As mentioned above, alternatively, in step 812, the first ECU 202 or the second ECU 204 does not use the yaw rate of the vehicle to determine the vehicle steady state condition. Instead, the first ECU 202 or the second ECU 204 detects that no steering position request is received from the VCU 700 within a predetermined time period. Accordingly, the first ECU 202 or the second ECU 204 infers from the non-existence of the received steering position request that the vehicle is in the going straight forward position. This means that step 810 is optional rather than essential.

[0118] In step 814, when the first ECU 202 or the second ECU 204 determines that the vehicle is in a vehicle steady state condition (e.g., in the going straight forward position), the first ECU 202 or the second ECU 204 is configured to determine whether the steering axis 200 is offset from the geometric center C.

[0119] If the first ECU 202 or the second ECU 204 determines that there is no offset of the steering axis 200 during the vehicle steady state condition, the first ECU 202 or the second ECU 204 returns to step 806, e.g., waiting for the next steering position request from the VCU 700.

[0120] If the first ECU 202 or the second ECU 204 determines that there is an offset of the steering axis 200, the first ECU 202 or the second ECU 204 generates a fault condition alert, as shown in step 816. The fault condition alert is sent to the VCU 700 via the CAN bus 702. Then, depending on the state of the vehicle, the first ECU 202 or the second ECU 204 returns to step 806, e.g., waiting for the next steering position request from the VCU 700. In some examples, the alert may indicate that inspection, repair, or maintenance is required. In some examples, optionally, the alert generated in step 816 is displayed to the user in the vehicle.

[0121] In step 814, the first ECU 202 or the second ECU 204 can determine that the steering axis 200 is offset in various different ways during the going straight forward position.

[0122] In some examples, after the first ECU 202 or the second ECU 204 has determined the vehicle steady state condition, the first ECU 202 or the second ECU 204 determines whether an axle center signal is received within a predetermined time period. The predetermined time period can be, for example, 0.1 s, 1 s, 5 s, 10 s, etc. If the first ECU 202 or the second ECU 204 does not receive the axle center signal within the predetermined time period, the first ECU 202 or the second ECU 204 determines that the midpoint 260 of the steering axle 200 is offset from the geometric center C of the steering assembly 100. Therefore, the first ECU 202 or the second ECU 204 is configured to generate an alarm in step 816 when the time of the offset of the steering axle 200 exceeds the predetermined time period.

[0123] In addition, in some other examples, the first ECU 202 or the second ECU 204 determines to receive the axle center signal at a determined frequency. In this case, the first ECU 202 or the second ECU 204 uses the information related to the wheel rotation and determines that the offset of the steering axle 200 depends on the wheel rotation. Therefore, the first ECU 202 or the second ECU 204 is configured to generate an alarm in step 816 when the steering axle 200 is offset and the offset changes as a function of the wheel rotation.

[0124] When the vehicle is in the straight-ahead position, a fault condition including wheel imbalance will cause a slight change in the height between the first tie rod 104 or the second tie rod 108 between the steering assembly 100 and the steering knuckle. These changes can be detected based on the small oscillation of the position of the steering axle 200, and the small oscillation of the position of the steering axle 200 will be proportional to the unbalanced rotation of the wheel. By synchronizing the oscillation of the steering axle 200 with the wheel rotation speed, the first ECU 202 or the second ECU 204 can determine that the oscillation that appears once rotated has a first-order property and is related to the unbalanced wheel or bearing. In addition, when the vehicle speed (or wheel speed) increases, the amplitude of the oscillation and the unbalanced force in the steering axle 200 will also increase. Therefore, the first ECU 202 or the second ECU 204 is capable of detecting the first-order oscillation. If the oscillation increases and decreases with the speed, the first ECU 202 or the second ECU 204 can determine that the cause is an unbalanced wheel, bearing, or worn bearing.

[0125] In some other examples, after the first ECU 202 or the second ECU 204 has determined the vehicle steady-state condition, the first ECU 202 or the second ECU 204 determines the magnitude of the displacement of the midpoint 260 of the steering shaft 200 from the geometric center C of the steering assembly 100. In some examples, the first ECU 202 or the second ECU 204 determines the displacement of the steering shaft 200 based on other sensor information. For example, the first ECU 202 or the second ECU 204 determines the displacement of the steering shaft 200 based on the rotation information of the first motor 208 or the second motor 210 as mentioned above. Alternatively, other sensor signals can be used to determine the displacement of the steering shaft 200. Then, the first ECU 202 or the second ECU 204 determines whether the displacement of the steering shaft 200 from the geometric center C exceeds a predetermined deviation. For example, in some examples, the screw actuator 228 is configured to adjust the steering shaft 200 within a tolerance of 0.05 mm. Therefore, the first ECU 202 or the second ECU 204 is configured to generate an alert in step 816 when the determined displacement of the steering shaft 200 exceeds 0.05 mm. For example, when the first tire experiences a sidewall reduction of approximately 70 mm, the displacement of the steering shaft 200 is 5 mm. Since 5 mm exceeds the predetermined threshold of 0.05 mm, the first ECU 202 or the second ECU 204 is configured to generate an alert in step 816.

[0126] In some other examples, the first ECU 202 or the second ECU 204 determines whether the yaw rate as a function of the displacement of the steering shaft 200 is within a predetermined range. Figure 9 A graph showing an example of the yaw rate versus the steering shaft displacement is shown. In normal operation, it is expected that the yaw rate-displacement relationship follows a predetermined linear relationship 900. In other examples, the first ECU 202 or the second ECU 204 determines that the yaw rate-displacement relationship follows a non-linear relationship. For example, the first ECU 202 or the second ECU 204 determines that the relationship between the yaw rate and the displacement is a sine function caused by the geometry of the steering assembly 100. For example, when the yaw rate of the vehicle is 0 radians per second (rad s -1 ) or within a predetermined yaw rate tolerance, the expected displacement of the steering shaft from the geometric center C at the first intersection 902 is 0 mm. In some examples, the predetermined yaw rate tolerance is ±0.01 rad s -1 , ±0.05 rad s -1 , ±0.1 rad s -1 , ±0.15 rad s -1 , ±0.2 rad s -1 , ±0.25 rad s -1 etc., or any other suitable predetermined yaw rate tolerance.

[0127] The first ECU 202 or the second ECU 204 is configured to determine whether the linear relationship between the yaw rate and the displacement is outside a predetermined linear relationship 900. For example, the allowable variation 906 outside the linear relationship may be ±0.05 mm. In Figure 9 it, the allowable variation 906 is represented as a dashed line region 906 around the predetermined linear relationship 900. At the second intersection 904, when the yaw rate is 0 rad s -1 the displacement of the steering axis 200 is determined to be 0.05 mm. Accordingly, the first ECU 202 or the second ECU 204 determines that this displacement of the steering axis 200 is acceptable because it is within the allowable variation 906. However, if the current displacement of the steering axis 200 exceeds the allowable variation 906, the first ECU 202 or the second ECU 204 will generate an alarm. In some examples, depending on its components and tolerances, the allowable variation 906 in the displacement can be any suitable displacement.

[0128] In some examples, the first ECU 202 or the second ECU 204 may determine that the linear relationship between the yaw rate and the displacement exhibits a different linear relationship 910 from the predetermined linear relationship 900. In this case, the first ECU 202 or the second ECU 204 may generate an alarm even if the determined displacement is within the allowable variation 906 of the predetermined linear relationship 900 (as shown by the overlapping region 908). This is because the change in the relationship between the yaw rate and the displacement indicates a fault condition.

[0129] Optionally, before the first ECU 202 or the second ECU 204 generates an alarm in step 816, the first ECU 202 or the second ECU 204 determines the type of fault in step 818.

[0130] As previously mentioned, when the first ECU 202 or the second ECU 204 determines that an offset occurs during the straight-ahead position, the offset may be due to, for example, a flat tire of the first wheel 504. However, the offset during the straight-ahead position may also be due to a non-standardized geometry of the chassis. To distinguish between a flat tire fault and a non-standardized geometry fault, the first ECU 202 or the second ECU 204 is configured to receive a tire pressure signal from the tire pressure sensor 706 from the CAN bus 702. If the first ECU 202 or the second ECU 204 determines, based on the tire pressure signal, that there is a low pressure in the first wheel 504, then in step 818, the first ECU 202 or the second ECU 204 confirms the existence of a flat tire fault. The alarm generated in step 816 may include information related to the type of fault condition of the vehicle.

[0131] In some examples, the tire pressure sensor 706 is a tire pressure monitoring system sensor (TPMS). This means that the tire pressure sensor 706 is installed in the valve of the tire and directly detects the pressure of the wheel. In some other examples, the tire pressure sensor 706 is an indirect tire pressure monitoring system (iTPMS) sensor. In this example, the tire pressure sensor 706 indirectly detects the tire pressure of the wheel based on the differential wheel speed rotation. The first ECU 202 or the second ECU 204 is configured to receive the tire pressure signal from the tire pressure sensor 706 via the CAN bus 702 or via another data connection, regardless of whether the tire pressure sensor 706 is a TPMS or an iTPMS.

[0132] Alternatively, if the first ECU 202 or the second ECU 204 determines that there is a normal pressure in the first wheel 504 based on the tire pressure signal, then in step 818, the first ECU 202 or the second ECU 204 confirms the existence of a non-standard geometry or a fault in the tire pressure sensor 706. The alarm generated in step 816 may include information related to the type of the fault condition of the vehicle.

[0133] When the first ECU 202 or the second ECU 204 determines that an offset occurs during the straight-ahead position, the offset may vary as a function of the wheel rotation. The first ECU 202 or the second ECU 204 receives the wheel rotation speed from the CAN bus 702. In this case, the first ECU 202 or the second ECU 204 determines that the change in the offset is a first-order response to the rotation of the first wheel 504. Then, in step 818, the first ECU 202 or the second ECU 204 determines that the first wheel 504 is unbalanced. The alarm generated in step 816 may include information related to the type of the fault condition of the vehicle.

[0134] In some other examples, the first ECU 202 or the second ECU 204 may receive information from a body or corner height sensor (not shown). The body height sensor is typically mounted to the vehicle suspension and detects the height of a specific point of the vehicle above the road. In step 818, the first ECU 202 or the second ECU 204 is configured to receive a signal from the body height sensor, as Figure 8 shown. Here, the first ECU 202 or the second ECU 204 can better determine the fault and the type of the fault, and increase the confidence of this determination when additionally using the signal received from the body height sensor.

[0135] In another example, two or more examples are combined. The features of one example can be combined with the features of other examples.

[0136] Examples of the present disclosure have been discussed with specific reference to the examples shown. However, it should be appreciated that variations and modifications can be made to the described examples within the scope of the present disclosure.

Claims

1. A steer-by-wire steering assembly (100) for a vehicle, comprising: Housing (102); At least one electronic control unit (202, 204); A motor assembly (250) having at least one rotor (214, 220) and at least one stator (212, 218), the at least one electronic control unit (202, 204) being configured to control the motor assembly (250); An actuator (228) operatively coupled to the at least one rotor (214, 220); A steering shaft (200) that can be connected to a first tie rod (104) and a second tie rod (108), the steering shaft (200) being configured to engage with the actuator (228) and, when the motor assembly (250) is actuated, the steering shaft moves longitudinally relative to the housing (102); A steering shaft displacement sensor (306) configured to send a signal to the at least one electronic control unit (202, 204) based on detecting a center reference target (400) of the steering shaft (200); Wherein the electronic control unit (202, 204) is configured to determine a vehicle steady state condition and, when the vehicle is in the vehicle steady state condition, determine a steering shaft offset based on the signal received from the steering shaft displacement sensor (306).

2. The steer-by-wire steering assembly (100) according to claim 1, wherein, The center reference target (400) indicates the midpoint of the steering shaft (200), and when the steering shaft displacement sensor (306) detects the center reference target (400), the midpoint of the steering shaft (200) is aligned with the geometric center of the steering assembly (100).

3. The steer-by-wire steering assembly (100) according to claim 1 or 2, wherein, The at least one electronic control unit (202, 204) is configured to determine the displacement of the steering shaft (200) based on the signal received from the steering shaft displacement sensor (306) and the rotation information of the at least one rotor (214, 220).

4. The steer-by-wire steering assembly (100) according to claim 1, wherein, The at least one electronic control unit (202, 204) is configured to receive an indication of the vehicle's stable state or information for determining the vehicle steady state condition.

5. The steer-by-wire steering assembly (100) according to claim 4, wherein, The at least one electronic control unit (202, 204) is configured to receive the indication of the vehicle's stable state or information for determining the vehicle steady state condition from a vehicle control unit (700), a vehicle motion controller, the vehicle's controller area network (702), a yaw rate sensor, at least one wheel speed sensor, or at least one body height sensor.

6. The steer-by-wire steering assembly (100) according to claim 4 or 5, wherein, The indication of the vehicle's stable state includes the yaw rate and / or wheel speed of the vehicle.

7. The steer-by-wire steering assembly (100) according to claim 6, wherein, When the yaw rate is 0 radians per second or approximately 0 radians per second, the at least one electronic control unit (202, 204) determines that the vehicle has a vehicle steady state condition.

8. The steer-by-wire steering assembly (100) according to any one of the preceding claims, wherein, The at least one electronic control unit (202, 204) is configured to determine a steering fault condition based on determining that the steering shaft has an offset when the vehicle is in a vehicle stable state.

9. The steer-by-wire steering assembly (100) according to claim 8, wherein, The at least one electronic control unit (202, 204) is configured to determine the steering fault condition when the steering shaft offset of the steering shaft exceeds a predetermined displacement.

10. The steer-by-wire steering assembly (100) according to claim 8, wherein, The at least one electronic control unit (202, 204) is configured to determine the steering fault condition when a period during which the steering shaft (200) is deflected exceeds a predetermined period.

11. The steer-by-wire steering assembly (100) according to any one of claims 8 to 10, wherein, The at least one electronic control unit (202, 204) is configured to determine the steering fault condition when a relationship between the steering shaft deflection and the yaw angular velocity of the vehicle exceeds a predetermined allowable variation.

12. The steer-by-wire steering assembly (100) according to any one of the preceding claims, wherein, The at least one electronic control unit (202, 204) is configured to determine that the steering shaft deflection varies according to wheel rotation and / or with wheel speed.

13. The steer-by-wire steering assembly (100) according to any one of claims 8 to 12, wherein, The at least one electronic control unit (202, 204) is configured to determine whether the steering fault condition is one or more of a tire pressure fault, a chassis geometry fault, a wheel imbalance, or a wheel bearing fault.

14. The steer-by-wire steering assembly (100) according to any one of the preceding claims, wherein, The at least one electronic control unit (202, 204) is configured to receive a signal from a tire pressure sensor (706) or a tire pressure loss sensor.

15. The steer-by-wire steering assembly (100) according to claim 14, wherein, The at least one electronic control unit (202, 204) is configured to determine a tire leak condition based on the signal received from the tire pressure sensor (706) and the steering fault condition.

16. The steer-by-wire steering assembly (100) according to any one of the preceding claims, wherein, The actuator (228) is a screw actuator configured to engage a threaded portion (1000) on the steering shaft (200).

17. The steer-by-wire steering assembly (100) according to any one of the preceding claims, wherein, The motor assembly (250) includes a first motor (208) and a second motor (210), the first motor having a first stator (212) including a first motor winding, the second motor having a second stator (218) including a second motor winding, wherein the at least one rotor (214, 220) is shared by the first motor (208) and the second motor (210).

18. The steer-by-wire steering assembly (100) according to any one of the preceding claims, wherein, The at least one electronic control unit (202, 204) is a first electronic control unit (202) and a second electronic control unit (204), the first electronic control unit being configured to control the first motor winding and the second electronic control unit being configured to control the second motor winding.

19. The steer-by-wire steering assembly (100) according to claim 14, wherein, The at least one electronic control unit (202, 204) is configured to determine a fault condition of the tire pressure sensor (706) based on the determined vehicle steady state condition and the signal received from the steering shaft displacement sensor (306).

20. A method of controlling a steer-by-wire steering assembly (100) for a vehicle, the steer-by-wire steering assembly having: a housing (102); at least one electronic control unit (202, 204); a motor assembly (250) having at least one rotor (214, 220) and at least one stator (212, 218), the at least one electronic control unit (202, 204) being configured to control the motor assembly (250); an actuator (228) operatively coupled to the at least one rotor (212, 218); and a steering shaft (200) that can be connected to a first tie rod (104) and a second tie rod (108), the steering shaft (200) being configured to engage with the actuator (228) and, when the motor assembly (250) is actuated, the steering shaft moves longitudinally relative to the housing (102), the method comprising: Detecting a central reference target (400) of the steering shaft (200) using a steering shaft displacement sensor (306); Sending a signal from the steering shaft displacement sensor (306) to the at least one electronic control unit (202, 204); Determining a vehicle steady state condition; When the vehicle is in a vehicle stable state, determining that a displacement of the steering shaft is deflected according to the signal received from the steering shaft displacement sensor (306).

21. A steer-by-wire steering assembly (100) for a vehicle, comprising: Housing (102); At least one electronic control unit (202, 204); A motor assembly (250), the motor assembly having at least one rotor (214, 220) and at least one stator (212, 218), the at least one electronic control unit (202, 204) being configured to control the motor assembly (250); An actuator (228), the actuator being operatively coupled to the at least one rotor (214, 220); A steering shaft (200), the steering shaft being connectable to a first tie rod (104) and a second tie rod (108), the steering shaft (200) being configured to engage with the actuator (228), and when the motor assembly (250) is actuated, the steering shaft moves longitudinally relative to the housing (102); A steering shaft displacement sensor (306), the steering shaft displacement sensor being configured to send a signal to the at least one electronic control unit (202, 204) based on detecting a center reference target (400) of the steering shaft (200), wherein the electronic control unit (202, 204) is configured to determine the rotation of the wheels (504, 506), and based on the signal received from the steering shaft displacement sensor (306), determine that the displacement of the steering shaft (200) is offset according to the rotation of the wheels (504, 506).

22. The steer-by-wire steering assembly (100) according to claim 21, wherein, The at least one electronic control unit (202, 204) is configured to determine the rotation of the wheels (504, 506) based on one or more of a wheel rotation sensor and an indication of wheel rotation.

23. The steer-by-wire steering assembly (100) according to claim 21 or 22, wherein, The at least one electronic control unit (202, 204) is configured to determine that the change in steering shaft offset is a first-order response to the rotation of the wheels (504, 506).

24. The steer-by-wire steering assembly (100) according to any one of claims 21 to 23, wherein, The at least one electronic control unit (202, 204) is configured to determine whether the wheels (504, 506) are unbalanced.

25. A steer-by-wire steering assembly (100) for a vehicle, comprising: A housing (102); At least one electronic control unit (202, 204); A motor assembly (250), the motor assembly having at least one rotor (214, 220) and at least one stator (212, 218), the at least one electronic control unit (202, 204) being configured to control the motor assembly (250); An actuator (228), the actuator being operatively coupled to the at least one rotor (214, 220); A steering shaft (200), the steering shaft being connectable to a first tie rod (104) and a second tie rod (108), the steering shaft (200) being configured to engage with the actuator (228), and when the first motor winding and / or the second motor winding is actuated, the steering shaft moves longitudinally relative to the housing (102); A steering shaft displacement sensor (206), the steering shaft displacement sensor being configured to send a signal to the at least one electronic control unit (202, 204) based on detecting a center reference target (400) of the steering shaft (200); At least one tire pressure sensor (706) or tire pressure loss sensor, the at least one tire pressure sensor or tire pressure loss sensor being configured to generate a pressure signal of a wheel mounted to the first tie rod (104) or the second tie rod (108). Wherein, the electronic control units (202, 204) are configured to determine a vehicle steady state condition, determine a steering axis offset based on a signal received from the steering axis displacement sensor (306), and determine a fault condition of the at least one tire pressure sensor (706) based on the determined vehicle steady state condition and the determined steering axis offset.

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