# US 9,434,406 B2 · Method for controlling end of travel for electric power-assisted steering > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,434,406 B2 - Document ID: US9434406B2 - Status: Granted - Kind: B2 - Application number: 14/385,386 - Filed: 2013-03-12 - Published: 2015-02-12 - Granted: 2016-09-06 - Earliest claimed: 2012-03-15 - Assignees: Jtekt Europe - Applicants: Jtekt Europe - Inventors: Alain Guilemond; Romain Moretti - Web page: https://patentgrep.com/patent/US9434406B2 ## CPC - B62D 5/0463: {calculating assisting torque from the motor based on driver input} - B62D 3/12: of rack-and-pinion type - B62D 5/0469: {End-of-stroke control} - B62D 5/0472: {for damping vibrations} - 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 method for controlling a steering system having an electric assistance motor in view of reducing shocks against end-of-travel stop, the method including getting a distance information of the rack with respect to the end of travel stop, getting an actual rotation speed information of the steering wheel, identifying a maximum allowed acceleration for the steering wheel, the maximum allowed acceleration being such that, in view of the distance information and the actual rotation speed information, the rotation speed of the steering wheel can decrease pursuant to a target deceleration value of a target deceleration profile so as to be lower than a required maximal speed when arriving at the end-of-travel stop, determining a maximum power assistance torque from the maximum allowed acceleration for controlling the power assistance torque applied to the assistance motor so as to target the deceleration value or profile of the rotation of the steering wheel. ## Claims ### Claim 1 A method for controlling end of travel, for a steering rack of a motor vehicle with electric power assistance, a method in which the maximum intensity of the electric current flowing through the electric power assistance motor is controlled to adapt a power assistance torque, at the approach of the end of travel positions of the rack, so as to reduce the shocks and noise when the steering system reaches a steering end-of-travel stop, said method comprising a specific function including: getting a distance information of the rack with respect to the end of travel stop, getting an actual rotation speed information of the steering wheel, identifying a maximum allowed acceleration for the rotation of the steering wheel, said maximum allowed acceleration being such that, in view of the distance information of the rack and the actual rotation speed information of the steering wheel, the rotation speed of the steering wheel will be lower than a required maximal speed when arriving at the end-of-travel stop, in respecting a target deceleration value or a target deceleration profile, determining a maximum power assistance torque from the maximum allowed acceleration; and controlling the power assistance torque so as to target the deceleration value or profile of the rotation of the steering wheel. ### Claim 2 (depends on 1) The method for controlling end of travel according to claim 1, comprising a main loop for controlling the power assistance torque, said main loop comprising providing a power assistance torque target according to assistance laws, while the specific function is implemented by a second loop and wherein said specific function is activated on a first condition that the absolute distance of the rack with respect to the end-of-travel stop is lower than a threshold value when approaching an end of travel position, and provided that the actual acceleration of the rotation of the steering wheel is higher than a threshold value, and further wherein said specific function, when activated, short-circuits the main loop so as to provide a new power assistance torque target to the assistance motor. ### Claim 3 (depends on 2) The method for controlling end of travel according to claim 2, wherein said specific function comprises measuring the actual power assistance torque, in particular at the time of the entry into operation of this function, so that said specific function achieves computing the maximum power assistance torque independently from the main loop. ### Claim 4 (depends on 2) The method for controlling end of travel according to claim 2, wherein said specific function is activated on a second condition that the vehicle speed is lower than a threshold value. ### Claim 5 (depends on 1) The method for controlling end of travel according to claim 1, further comprising a preliminary step of determining the positions of the two mechanic end of travel stops of the rack, by calculating the absolute distance with respect to the stop to which the rack is the closest, based on a position information provided by an encoder associated with the electric power assistance motor, or by an angular position sensor of the steering wheel or of the steering column. ### Claim 6 (depends on 1) The method of claim 1 comprising: getting an actual rotation acceleration of the steering wheel, comparing the actual rotation acceleration of the steering wheel with the maximum allowed acceleration, so as to obtain a deviation, converting the deviation into a decrease target of the power assistance torque, and determining a maximum power assistance torque by subtracting the decrease target of the power assistance torque from an actual power assistance torque. ### Claim 7 (depends on 1) The method of claim 1 wherein getting an actual rotation acceleration of the steering wheel comprises calculating said actual rotation acceleration from the actual rotation speed information. ### Claim 8 (depends on 2) The method of claim 2 wherein short-circuiting the main loop is achieved in saturating the power assistance torque target outputted by the main loop with the maximum power assistance torque computed by the second loop.