# US 12,005,973 B2 · Steering system and method for operating a steering system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,005,973 B2 - Document ID: US12005973B2 - Status: Granted - Kind: B2 - Application number: 17/476,799 - Filed: 2021-09-16 - Published: 2022-03-17 - Granted: 2024-06-11 - Earliest claimed: 2020-09-17 - Assignees: Ford Global Technologies, LLC - Applicants: Ford Global Technologies, LLC - Inventors: Fabian Roeckner; Simon Nolden; Jens Dornhege - Web page: https://patentgrep.com/patent/US12005973B2 ## CPC - B62D 5/0463: {calculating assisting torque from the motor based on driver input} - B62D 5/0484: {for reaction to failures, e.g. limp home} - B62D 5/0403: {characterised by constructional features, e.g. common housing for motor and gear box} - B62D 5/0481: {monitoring the steering system, e.g. failures} - B62D 6/008: {Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications} - B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M) ## Abstract A steering system for a motor vehicle may include a steering wheel actuator mechanically connectable to a steering wheel of the motor vehicle, and a control unit operably coupled to the steering wheel actuator. The control unit may be configured to determine a target steering wheel torque via which the steering wheel actuator is activatable. The target steering wheel torque may be determined from a present state parameter of the motor vehicle using a steering wheel torque algorithm. The control unit may be configured to determine whether the target steering wheel torque is considered plausible or not plausible based on the present state parameter of the motor vehicle via a plausibility algorithm, determine a fallback steering wheel torque via an auxiliary algorithm, and use the fallback steering wheel torque instead of the target steering wheel torque as a target steering wheel torque request if the target steering wheel torque is not plausible. ## Claims ### Claim 1 A steering system for a motor vehicle, the steering system comprising: a steering wheel actuator mechanically connectable to a steering wheel of the motor vehicle; and a control unit operably coupled to the steering wheel actuator, the control unit being configured to determine a target steering wheel torque via which the steering wheel actuator is activatable, the target steering wheel torque being determined from a present state parameter of the motor vehicle using a steering wheel torque algorithm, wherein the control unit is configured to: determine whether the target steering wheel torque is considered plausible or not plausible based on the present state parameter of the motor vehicle via a plausibility algorithm, determine a fallback steering wheel torque via an auxiliary algorithm, and use the fallback steering wheel torque instead of the target steering wheel torque as a target steering wheel torque request if the target steering wheel torque is not plausible, wherein determining whether the target steering wheel torque is considered plausible or not plausible via the plausibility algorithm comprises: comparing a direction of the target steering wheel torque to a direction of a present steering wheel angular velocity, comparing the target steering wheel torque to a torque threshold value, and comparing the present steering wheel angular velocity to a velocity threshold value if the direction of the target steering wheel torque corresponds to the direction of the present steering wheel angular velocity. ### Claim 2 (depends on 1) The steering system of claim 1, wherein the control unit is configured to use the fallback steering wheel torque instead of the target steering wheel torque as the target steering wheel torque request if the target steering wheel torque is greater than the torque threshold value and the present steering wheel angular velocity is greater than the velocity threshold value. ### Claim 3 (depends on 2) The steering system of claim 2, wherein the control unit is configured to determine from sensor data whether a driver of the motor vehicle presently performs a steering process on the steering wheel, and to vary the torque threshold value as a function of at least one property of the steering process. ### Claim 4 (depends on 3) The steering system of claim 3, wherein the control unit is configured to determine from the sensor data a toothed rack force acting on at least one steerable running wheel of the motor vehicle, to compare a direction of the toothed rack force to a direction of the steering wheel angular velocity, and to increase the velocity threshold value as a function of a strength of the toothed rack force if the direction of the toothed rack force corresponds to the direction of the steering wheel angular velocity. ### Claim 5 (depends on 4) The steering system of claim 4, wherein the control unit is configured to increase the torque threshold value and/or the velocity threshold value if the travel velocity of the motor vehicle drops. ### Claim 6 (depends on 2) The steering system of claim 2, wherein the control unit is configured to evaluate a ratio of a steering torque presently applied by a driver to the steering wheel to the present steering wheel angular velocity. ### Claim 7 (depends on 1) The steering system of claim 1, wherein the control unit is configured to limit the target steering wheel torque to a settable maximum threshold value and to set the maximum threshold value as a function of the present state parameter of the motor vehicle. ### Claim 8 (depends on 1) The steering system of claim 1, wherein the control unit is configured to use the fallback steering wheel torque instead of the target steering wheel torque as the target steering wheel torque request only when the target steering wheel torque is not plausible over a time period of predetermined length. ### Claim 9 (depends on 1) The steering system of claim 1, wherein the steering system is a steer-by-wire steering system. ### Claim 10 A method for operating a steering system of a motor vehicle, the steering system comprising a steering wheel actuator mechanically connectable to a steering wheel of the motor vehicle, and a control unit operably coupled to the steering wheel actuator, the control unit being configured to determine a target steering wheel torque via which the steering wheel actuator is activatable, the target steering wheel torque being determined from a present state parameter of the motor vehicle using a steering wheel torque algorithm, the method comprising: determining whether the target steering wheel torque is considered plausible or not plausible based on the present state parameter of the motor vehicle via a plausibility algorithm, determining a fallback steering wheel torque via an auxiliary algorithm, and using the fallback steering wheel torque instead of the target steering wheel torque as a target steering wheel torque request if the target steering wheel torque is not plausible, wherein determining whether the target steering wheel torque is considered plausible or not plausible via the plausibility algorithm comprises: comparing a direction of the target steering wheel torque to a direction of a present steering wheel angular velocity, comparing the target steering wheel torque to a torque threshold value, and comparing the present steering wheel angular velocity to a velocity threshold value if the direction of the target steering wheel torque corresponds to the direction of the present steering wheel angular velocity. ### Claim 11 (depends on 10) The method of claim 10, wherein using the fallback steering wheel torque instead of the target steering wheel torque as the target steering wheel torque request is performed responsive to the target steering wheel torque being greater than the torque threshold value and the present steering wheel angular velocity being greater than the velocity threshold value. ### Claim 12 (depends on 11) The method of claim 11, further comprising determining from sensor data whether a driver of the motor vehicle presently performs a steering process on the steering wheel, and to vary the torque threshold value as a function of at least one property of the steering process. ### Claim 13 (depends on 12) The method of claim 12, further comprising determining from the sensor data a toothed rack force acting on at least one steerable running wheel of the motor vehicle, comparing a direction of the toothed rack force to a direction of the steering wheel angular velocity, and increasing the velocity threshold value as a function of a strength of the toothed rack force if the direction of the toothed rack force corresponds to the direction of the steering wheel angular velocity. ### Claim 14 (depends on 13) The method of claim 13, further comprising increasing the torque threshold value and/or the velocity threshold value if the travel velocity of the motor vehicle drops. ### Claim 15 (depends on 11) The method of claim 11, further comprising evaluating a ratio of a steering torque presently applied by a driver to the steering wheel to the present steering wheel angular velocity. ### Claim 16 (depends on 10) The method of claim 10, further comprising limiting the target steering wheel torque to a settable maximum threshold value and to set the maximum threshold value as a function of the present state parameter of the motor vehicle. ### Claim 17 (depends on 10) The method of claim 10, wherein using the fallback steering wheel torque instead of the target steering wheel torque as the target steering wheel torque request is only performed when the target steering wheel torque is not plausible over a time period of predetermined length. ### Claim 18 (depends on 1) The steering system of claim 1, wherein responsive to the direction of the target steering wheel torque being different from the direction of the present steering wheel angular velocity, the control unit determines that the target steering wheel torque is plausible. ### Claim 19 (depends on 1) The steering system of claim 1, wherein responsive to the target steering wheel torque being less than the torque threshold value, the control unit determines that the target steering wheel torque is plausible. ### Claim 20 (depends on 1) The steering system of claim 1, wherein responsive to the steering wheel angular velocity being less than the velocity threshold value, the control unit determines that the target steering wheel torque is plausible.