# US 2008/0185212 A1 · Vehicle steering system, vehicle including the same and method for turning wheel of vehicle > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0185212 A1 - Document ID: US20080185212A1 - Status: Published application - Kind: A1 - Application number: 11/939,442 - Filed: 2007-11-13 - Published: 2008-08-07 - Earliest claimed: 2007-02-06 - Assignees: Honda Motor Co., Ltd. - Inventors: Yoshimitsu Akuta; Takuya Yamaguchi - Web page: https://patentgrep.com/patent/US20080185212A1 ## CPC - B62D 6/002: {computing target steering angles for front or rear wheels (B62D7/159 takes precedence)} - 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 vehicle steering system includes a steering wheel, a steering angle detector that detects a steering angle of the steering wheel, a steering angular speed calculator that calculates a steering angular speed of the steering wheel, a vehicle speed detector that detects a vehicle speed, a target rudder angle finding device, a modifying device, and an actuator. The target rudder angle finding device finds a target rudder angle based on the steering angle, the steering angular speed and the vehicle speed. The target rudder angle is a sum of a proportional term proportional to the steering angle and a differential term proportional to the steering angular speed. The modifying device modifies the differential term when the steering angular speed is negative to reduce a value of the differential term from that when positive. The actuator turns at least one wheel of the vehicle in accordance with the target rudder angle. ## Claims ### Claim 1 A vehicle steering system comprising: a steering wheel; a steering angle detector for detecting a steering angle of the steering; a steering angular speed calculator for calculating a steering angular speed of the steering; a vehicle speed detector for detecting a vehicle speed; a target rudder angle finding device for finding a target rudder angle which is based on the steering angle, the steering angular speed, and the vehicle speed; and an actuator for turning at least one wheel of the vehicle in accordance with the target rudder angle, wherein the target rudder angle is a sum of a proportional term in proportion to the steering angle and a differential term in proportion to the steering angular speed, and wherein a modifying device modifies a value of the differential term smaller when the steering angular speed is negative comparing to a value of the differential term with a positive angular speed. ### Claim 2 (depends on 1) The vehicle steering system according to claim 1, wherein the target rudder angle finding device calculates the proportional term with multiplying the steering angle and a proportional control gain which changes according to a change in the vehicle speed. ### Claim 3 (depends on 2) The vehicle steering system according to claim 2, wherein a value of the proportional control gain is reduced in accordance with the vehicle speed increases. ### Claim 4 (depends on 1) The vehicle steering system according to claim 1, wherein the target rudder angle finding device calculates the differential term with multiplying the steering angular speed and at least a differential control gain which changes according to a change in the vehicle speed. ### Claim 5 (depends on 4) The vehicle steering system according to claim 4, wherein a value of the differential control gain is reduced in accordance with the vehicle speed increases. ### Claim 6 (depends on 1) The vehicle steering system according to claim 1, wherein the target rudder angle finding device calculates the differential term with multiplying the steering angular speed and a modified differential control gain, wherein the modifying device calculates the modified differential control gain with multiplying the differential control gain and a correction coefficient, and wherein a value of the correction coefficient is smaller when the steering angular speed is negative comparing to a value of the correction coefficient with a positive steering angular speed. ### Claim 7 (depends on 6) The vehicle steering system according to claim 6, wherein the correction coefficient includes a first correction coefficient and a second correction coefficient, the first correction coefficient being used as the correction coefficient when the steering angular speed is positive or zero, the second correction coefficient being used as the correction coefficient when the steering angular speed is negative, the second correction coefficient being smaller than the first correction coefficient. ### Claim 8 A vehicle steering system comprising: a steering wheel; steering angle detection means for detecting a steering angle of the steering wheel; steering angular speed calculation means for calculating a steering angular speed of the steering wheel; vehicle speed detection means for detecting a vehicle speed; target rudder angle finding means for finding a target rudder angle which is based on the steering angle, the steering angular speed and the vehicle speed; and actuator means for turning at least one wheel of the vehicle in accordance with the target rudder angle, wherein the target rudder angle is a sum of a proportional term in proportion to the steering angle and a differential term in proportion to the steering angular speed, and wherein modifying means modifies a value of the differential term smaller when the steering angular speed is negative comparing to a value of the differential term with a positive angular speed. ### Claim 9 A vehicle comprising: a wheel; a steering wheel; a steering angle detector for detecting a steering angle of the steering wheel; a steering angular speed calculator for calculating a steering angular speed of the steering wheel; a vehicle speed detector for detecting a vehicle speed; a target rudder angle finding device for finding a target rudder angle which is based on the steering angle, the steering angular speed, and the vehicle speed; and an actuator for turning at least one wheel of the vehicle in accordance with the target rudder angle; wherein the target rudder angle is a sum of a proportional term in proportion to the steering angle and a differential term in proportion to the steering angular speed, and wherein a modifying device modifies the differential term smaller when the steering angular speed is negative comparing to a value of the differential term with a positive angular speed. ### Claim 10 A method for turning at least one wheel of a vehicle comprising: detecting a steering angle of a steering wheel of the vehicle; calculating a steering angular speed of the steering wheel; detecting a vehicle speed; finding a target rudder angle which is based on the steering angle, the steering angular speed, and the vehicle speed; modifying a value of the differential term smaller when the steering angular speed is negative comparing to a value of the differential term with positive angular speed; and turning at least one wheel of the vehicle in accordance with the target rudder angle, wherein the target rudder angle is a sum of a proportional term in proportion to the steering angle and a differential term in proportion to the steering angular speed.