# US 11,305,813 B2 · Emergency steering apparatus and method of motor driven power steering system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,305,813 B2 - Document ID: US11305813B2 - Status: Granted - Kind: B2 - Application number: 16/448,406 - Filed: 2019-06-21 - Published: 2019-12-26 - Granted: 2022-04-19 - Earliest claimed: 2018-06-22 - Assignees: Hyundai Mobis Co., Ltd. - Applicants: Hyundai Mobis Co., Ltd. - Inventors: Tae Hong Kim - Web page: https://patentgrep.com/patent/US11305813B2 ## CPC - B62D 6/00: Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits (means for initiating a change in direction B62D1/00; steering valves B62D5/06; combined with means for inclining the vehicle body or wheels on bends B62D9/00) - 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 5/049: {detecting sensor failures} - 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 An emergency steering apparatus of an MDPS (Motor Driven Power Steering) system may include: a steering angle sensor configured to sense a steering angle of a steering wheel; a vehicle speed sensor configured to sense a vehicle speed; an assist rack force detector configured to detect an assist rack force of the MDPS system using the steering angle sensed by the steering angle sensor and the vehicle speed sensed by the vehicle speed sensor; and a command current detector configured to detect a command current of a motor using the assist rack force detected by the assist rack force detector ## Claims ### Claim 1 An emergency steering apparatus of an MDPS (Motor Driven Power Steering) system, comprising: a steering angle sensor configured to sense a steering angle of a steering wheel; a vehicle speed sensor configured to sense a vehicle speed; an assist rack force detector configured to detect an assist rack force of the MDPS system using the steering angle sensed by the steering angle sensor and the vehicle speed sensed by the vehicle speed sensor, the assist rack force detector comprising an assist rack force calculator configured to calculate an assist rack force based on a total rack force and a driver max steering force by subtracting the driver max steering force from the total rack force, wherein the total rack force is calculated based on a self-aligning torque, wherein the driver max steering force is calculated by the assist rack force calculator using pinion efficiency, driver maximum torque, and pinion gear ratio; and a command current detector configured to detect a command current of a motor using the assist rack force detected by the assist rack force detector. ### Claim 2 (depends on 1) The emergency steering apparatus of claim 1, wherein the assist rack force detector further comprises: a total rack force calculator configured to calculate a total rack force required for a driver to operate a steering wheel, using the steering angle sensed by the steering angle sensor and the vehicle speed sensed by the vehicle speed sensor. ### Claim 3 (depends on 2) The emergency steering apparatus of claim 2, wherein the total rack force calculator calculates a side slip angle and yaw rate of the vehicle, using the steering angle sensed by the steering angle sensor and the vehicle speed sensed by the vehicle speed sensor, calculates the self-aligning torque based on a detected side slip angle and yaw rate of the vehicle, and then calculates the total rack force based on the calculated self-aligning torque. ### Claim 4 (depends on 3) The emergency steering apparatus of claim 3, further comprising a command current corrector configured to correct a command current according to the yaw rate calculated by the total rack force calculator. ### Claim 5 (depends on 4) The emergency steering apparatus of claim 4, wherein the command current corrector compares the yaw rate calculated by the total rack force calculator to the yaw rate sensed by the yaw rate sensor, and adjusts a magnitude of the command current according to the comparison. ### Claim 6 (depends on 5) The emergency steering apparatus of claim 5, wherein the command current corrector compares patterns or magnitudes of the yaw rate calculated by the total rack force calculator and the yaw rate sensed by the yaw rate sensor, and determines a behavior of the vehicle as any one of normal turn, over-steer and under-steer, according to a similarity therebetween. ### Claim 7 (depends on 6) The emergency steering apparatus of claim 6, wherein the command current corrector determines that the behavior of the vehicle is over-steer, when the yaw rate sensed by the yaw rate sensor is larger than the yaw rate calculated by the total rack force calculator, and determines that the behavior of the vehicle is under-steer, when the yaw rate sensed by the yaw rate sensor is smaller than the yaw rate calculated by the total rack force calculator. ### Claim 8 (depends on 5) The emergency steering apparatus of claim 5, wherein the command current corrector adjusts the magnitude of the command current by applying a difference between the yaw rate calculated by the total rack force calculator and the yaw rate sensed by the yaw rate sensor to a preset tuning map. ### Claim 9 (depends on 2) The emergency steering apparatus of claim 2, wherein the assist rack force calculator calculates the ratio of the assist rack force with respect to the total rack force calculated by the total rack force calculator, in order to calculate the assist rack force. ### Claim 10 (depends on 9) The emergency steering apparatus of claim 9, wherein the assist rack force calculator calculates the assist rack force by multiplying the ratio of the assist rack force by the total rack force calculated by the total rack force calculator. ### Claim 11 (depends on 1) The emergency steering apparatus of claim 1, further comprising a command current corrector configured to previously store a gain adjustment table based on the vehicle speed sensed by the vehicle speed sensor, and correct the command current detected by the command current detector by applying a gain of the gain adjustment table according to the vehicle speed sensed by the vehicle speed sensor. ### Claim 12 An emergency steering method of an MDPS system, comprising: calculating, by an assist rack force detector, a total rack force required for a driver to operate a steering wheel, using a steering angle and vehicle speed which are sensed by a steering angle sensor and a vehicle speed sensor, respectively, and calculating an assist rack force based on the calculated total rack force and a driver max steering force by subtracting the driver max steering force from the total rack force, wherein the total rack force is calculated based on a self-aligning torque, wherein the driver max steering force is calculated by an assist rack force calculator using pinion efficiency, driver maximum torque, and pinion gear ratio; and detecting, by a command current detector, a command current of a motor using the assist rack force detected by the assist rack force detector. ### Claim 13 (depends on 12) The emergency steering method of claim 12, wherein in the calculating of the total rack force, a total rack force calculator calculates a side slip angle and yaw rate of the vehicle, using the steering angle sensed by the steering angle sensor and the vehicle speed sensed by the vehicle speed sensor, calculates the self-aligning torque based on a detected side slip angle and yaw rate of the vehicle, and then calculates the total rack force based on the calculated self-aligning torque. ### Claim 14 (depends on 12) The emergency steering method of claim 12, further comprising correcting, by a command current corrector, a command current according to a yaw rate calculated by the total rack force calculator. ### Claim 15 (depends on 14) The emergency steering method of claim 14, wherein in the correcting of the command current, the command current corrector compares the yaw rate calculated by the total rack force calculator and the yaw rate sensed by a yaw rate sensor, and adjusts a magnitude of the command current according to the comparison. ### Claim 16 (depends on 15) The emergency steering method of claim 15, wherein in the correcting of the command current, the command current corrector compares patterns or magnitudes of the yaw rate calculated by the total rack force calculator to the yaw rate sensed by the yaw rate sensor, and determines a behavior of the vehicle as any one of normal turn, over-steer and under-steer, according to a similarity therebetween. ### Claim 17 (depends on 16) The emergency steering method of claim 16, wherein in the correcting of the command current, the command current corrector determines that the behavior of the vehicle is over-steer, when the yaw rate sensed by the yaw rate sensor is larger than the yaw rate calculated by the total rack force calculator, and determines that the behavior of the vehicle is under-steer when the yaw rate sensed by the yaw rate sensor is smaller than the yaw rate calculated by the total rack force calculator. ### Claim 18 (depends on 15) The emergency steering method of claim 15, wherein in the correcting of the command current, the command current corrector adjusts the magnitude of the command current by applying a difference between the yaw rate calculated by the total rack force calculator and the yaw rate sensed by the yaw rate sensor to a preset tuning map. ### Claim 19 (depends on 12) The emergency steering method of claim 12, wherein in the calculating of the assist rack force, the assist rack force calculator calculates the ratio of the assist rack force with respect to the total rack force calculated by the total rack force calculator, in order to calculate the assist rack force. ### Claim 20 (depends on 19) The emergency steering method of claim 19, wherein in the calculating of the assist rack force, the assist rack force calculator calculates the assist rack force by multiplying the ratio of the assist rack force by the total rack force calculated by the total rack force calculator.