# US 2008/0189014 A1 · Vehicular steering apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0189014 A1 - Document ID: US20080189014A1 - Status: Published application - Kind: A1 - Application number: 11/591,608 - Filed: 2006-11-02 - Published: 2008-08-07 - Earliest claimed: 2005-11-02 - Assignees: Mitsubishi Electric Corporation - Inventors: Hideyuki Tanaka; Takanori Matsunaga; Masahiko Kurishige; Takayuki Kifuku - Web page: https://patentgrep.com/patent/US20080189014A1 ## CPC - B62D 5/0466: {for returning the steering wheel to neutral position} - 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 Provided is a vehicular steering apparatus capable of improving a steering feeling and achieving a reduction in cost. The vehicular steering apparatus according to the present invention is equipped with an assist motor for generating an assist torque, a state quantity detector for detecting a steering shaft reaction torque and a road surface reaction torque, and a control unit for calculating a target current value of the assist motor. The control unit includes a friction compensation portion and a return compensation portion, which calculate a friction compensation torque for compensating for the assist torque and a return compensation torque for compensating for the assist torque from the steering shaft reaction torque and the road surface reaction torque respectively. The control unit compensates for an overall friction torque in a steering mechanism and a gradient of the road surface reaction torque, using the friction compensation torque and the return compensation torque. ## Claims ### Claim 1 A vehicular steering apparatus, comprising: a motor for generating an assist torque for supplementing a steering torque exerted by a driver of a vehicle; steering shaft reaction torque detecting means for detecting a steering shaft reaction torque generated on a steering shaft of the vehicle and having hysteresis characteristics; road surface reaction torque detecting means for detecting a road surface reaction torque received by wheels of the vehicle from a road surface; and target current calculating means for calculating a target current value for driving the motor, wherein: the target current calculating means includes first compensation means for calculating a first compensation amount for compensating for the assist torque based on the steering shaft reaction torque, and second compensation means for calculating a second compensation amount for compensating for the assist torque based on the road surface reaction torque; and the target current calculating means calculates the target current so that compensation for an overall friction torque generated in an entire steering mechanism of the vehicle and a gradient of the road surface reaction torque is performed based on the first compensation amount and the second compensation amount. ### Claim 2 (depends on 1) A vehicular steering apparatus according to claim 1, wherein: the first compensation amount is a compensation amount for compensating for the assist torque in a steering direction of the driver; and the second compensation amount is a compensation amount for compensating for the assist torque in a direction opposite to the steering direction of the driver. ### Claim 3 (depends on 1) A vehicular steering apparatus according to claim 1, wherein the road surface reaction torque is obtained by subtracting the overall friction torque from the steering shaft reaction torque. ### Claim 4 (depends on 1) A vehicular steering apparatus according to claim 1, wherein: the steering shaft reaction torque detecting means comprises steering torque detecting means for detecting the steering torque, and motor current detecting means for detecting a motor current flowing through the motor; and the steering shaft reaction torque is calculated based on the steering torque and the motor current. ### Claim 5 (depends on 1) A vehicular steering apparatus according to claim 1, wherein: the steering shaft reaction torque detecting means comprises steering wheel angle detecting means for detecting a steering wheel angle of a steering wheel of the vehicle, vehicle speed detecting means for detecting a vehicle speed of the vehicle, and friction torque detecting means for detecting the overall friction torque generated in the entire steering mechanism of the vehicle; and the steering shaft reaction torque is calculated based on the steering wheel angle, the vehicle speed, and the overall friction torque. ### Claim 6 (depends on 1) A vehicular steering apparatus according to claim 1, wherein: the road surface reaction torque detecting means comprises steering wheel angle detecting means for detecting a steering wheel angle of a steering wheel of the vehicle and vehicle speed detecting means for detecting a vehicle speed of the vehicle; and the road surface reaction torque is calculated based on the steering wheel angle and the vehicle speed. ### Claim 7 (depends on 1) A vehicular steering apparatus according to claim 1, wherein the first compensation amount is smaller than the overall friction torque. ### Claim 8 (depends on 1) A vehicular steering apparatus according to claim 1, further comprising vehicle speed detecting means for detecting a vehicle speed of the vehicle, wherein the first compensation amount has an upper limit and a lower limit that are variably set based on the vehicle speed. ### Claim 9 (depends on 1) A vehicular steering apparatus according to claim 1, wherein the first compensation amount is variably set based on the road surface reaction torque. ### Claim 10 (depends on 1) A vehicular steering apparatus according to claim 1, wherein the first compensation amount and the second compensation amount are calculated using gains that are variably set according to a type of the vehicle. ### Claim 11 (depends on 1) A vehicular steering apparatus according to claim 1, wherein the first compensation amount and the second compensation amount are calculated using limiter values that are variably set according to a type of the vehicle.