# US 9,434,388 B2 · Surface estimation for vehicles > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,434,388 B2 - Document ID: US9434388B2 - Status: Granted - Kind: B2 - Application number: 14/530,255 - Filed: 2014-10-31 - Published: 2016-05-05 - Granted: 2016-09-06 - Earliest claimed: 2014-10-31 - Assignees: GM Global Technology Operations LLC - Applicants: GM Global Technology Operations LLC - Inventors: Fred W. Huntzicker; Paul R. Williams; Daniel R. Gee - Web page: https://patentgrep.com/patent/US9434388B2 ## CPC - B60W 40/068: Road friction coefficient - B60W 40/06: Road conditions - 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) - B60W 2520/26: Wheel slip - B60W 2556/45: External transmission of data to or from the vehicle - B60W 2720/30: Wheel torque - B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT - 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 Methods and systems are provided for estimating a characteristic of a surface of a road on which a vehicle is travelling is provided. The system comprises a sensor and a processor. The sensor is configured to measure information pertaining to a wheel slip for one or more wheels of the vehicle after a torque is applied. The processor is coupled to the sensor, and is configured to at least facilitate applying the torque for the one or more wheels of the vehicle, and estimating the characteristic of the surface of the road based at least in part on the wheel slip after the torque is applied and the torque. ## Claims ### Claim 1 A method for estimating a characteristic of a surface of a road on which a vehicle is travelling, the method comprising; applying a torque of a particular magnitude for one or more wheels of the vehicle; determining a first wheel slip for the one or more wheels prior to applying the torque; determining a second wheel slip for the one or more wheels subsequent to applying the torque; determining a wheel slip difference between the second wheel slip and the first wheel slip; and estimating the characteristic of the surface of the road based at least in part on the wheel slip difference and the magnitude of the applied torque. ### Claim 2 (depends on 1) The method of claim 1, wherein the step of applying the torque comprises applying different amounts of torque to different respective wheels of the vehicle so that a total net torque about a center of the vehicle from the applied torque is equal to zero. ### Claim 3 (depends on 1) The method of claim 1, wherein the step of applying the torque comprises applying different amounts of torque to different respective wheels of the vehicle in a matter that is balanced diagonally across the vehicle. ### Claim 4 (depends on 1) The method of claim 1, wherein the step of applying the torque comprises applying different amounts of torque to different respective wheels of the vehicle via torque vectoring. ### Claim 5 (depends on 1) The method of claim 1, wherein the step of applying the torque comprises applying a brake drag on a first of the wheels of the vehicle and applying a compensating positive torque on a second of the wheels of the vehicle. ### Claim 6 (depends on 1) The method of claim 1, further comprising: modifying the applied torque in a sinusoidal manner with a modified magnitude; determining an updated wheel slip difference based on the modification of the applied torque in the sinusoidal manner; and estimating an updated characteristic of the surface of the road based at least in part on the updated wheel slip difference and the modified magnitude of the torque applied in the sinusoidal manner. ### Claim 7 (depends on 1) The method of claim 1, further comprising: providing a steering angle adjustment that compensates for the applied torque. ### Claim 8 (depends on 1) The method of claim 1, further comprising: receiving information from one or more remote sources as to the characteristic of the surface; and updating the estimated characteristic of the surface using the received information. ### Claim 9 (depends on 1) The method of claim 1, further comprising: transmitting, via a transmitter, the estimated characteristic of the surface for use on one or more other vehicles. ### Claim 10 (depends on 9) The method of claim 9, further comprising: receiving, via a receiver, a different value of the characteristic of the surface from one or more other vehicles; and updating, via the processor, the estimated characteristic of the surface using the different value that was received from the one or more other vehicles. ### Claim 11 (depends on 10) The method of claim 10, wherein the step of updating the estimated characteristic comprises: averaging the estimated characteristic of the surface as generated by the processor with the different value of the characteristic as received via the receiver, to thereby generate the updated estimate of the characteristic of the surface. ### Claim 12 A system for estimating a characteristic of a surface of a road on which a vehicle is travelling, the system comprising: a sensor configured to measure information pertaining to a first wheel slip for one or more wheels of the vehicle before a torque of a particular magnitude is applied and a second wheel slip for the one or more wheels after the torque is applied; and a processor coupled to the sensor and configured to at least facilitate: applying the torque for the one or more wheels of the vehicle; determining a wheel slip difference between the second wheel slip and the first wheel slip; and estimating the characteristic of the surface of the road based at least in part on the wheel slip difference and the magnitude of the applied torque. ### Claim 13 (depends on 12) The system of claim 12, wherein the processor is configured to at least facilitate: applying different amounts of torque to different respective wheels of the vehicle so that a total net torque about a center of the vehicle from the applied torque is equal to zero; determining the wheel slip difference based on respective wheel slips before and after the application of different amounts of torque are applied in the manner so that the total net torque about the center of the vehicle from the applied torque is equal to zero; and estimating the characteristic of the surface based at least in part on the wheel slip difference from the application of different amounts of torque are applied in the manner so that the total net torque about the center of the vehicle from the applied torque is equal to zero. ### Claim 14 (depends on 12) The system of claim 12, wherein the processor is configured to at least facilitate: applying different amounts of torque to different respective wheels of the vehicle in a matter that is balanced diagonally across the vehicle; determining the wheel slip difference based on respective wheel slips before and after the different amounts of torque are applied in the manner that is balanced diagonally across the vehicle; and estimating the characteristic of the surface based at least in part on the wheel slip difference from the application of the different amounts of torque applied in the manner that is diagonally balanced across the vehicle. ### Claim 15 (depends on 12) The system of claim 12, wherein the processor is configured to at least facilitate: applying different amounts of torque to different respective wheels of the vehicle via torque vectoring; determining the wheel slip difference based on respective wheel slips before and after the different amounts of torque are applied via the torque vectoring; and estimating the characteristic of the surface based at least in part on the wheel slip difference from the application of the different amounts of torque applied via the torque vectoring. ### Claim 16 (depends on 12) The system of claim 12, wherein the processor is configured to at least facilitate: applying a brake drag on a first of the wheels of the vehicle and applying a compensating positive torque on a second of the wheels of the vehicle; determining the wheel slip difference based on respective wheel slips before and after the applying of the brake drag; and estimating the characteristic of the surface based at least in part on the applying of the brake drag. ### Claim 17 (depends on 12) The system of claim 12, wherein the processor is configured to at least facilitate: modifying the applied torque in a sinusoidal manner; determining an updated wheel slip difference based on the modification of the applied torque in the sinusoidal manner; and estimating an updated characteristic of the surface of the road based at least in part on the updated wheel slip difference and the modified magnitude of the torque applied in the sinusoidal manner. ### Claim 18 (depends on 12) The system of claim 12, wherein the processor is configured to at least facilitate providing a steering angle adjustment that compensates for the applied torque. ### Claim 19 (depends on 12) The system of claim 12, further comprising: a receiver configured to at least facilitate receiving information from one or more remote sources as to the characteristic of the surface; wherein the processor is further configured to at least facilitate updating the estimated characteristic of the surface using the received information. ### Claim 20 A vehicle comprising: a plurality of wheels; a sensor configured to measure information pertaining to a first wheel slip for one or more of the plurality of wheels before a torque of a particular magnitude is applied and a second wheel slip for the one or more wheels after a torque is applied; and a processor coupled to the sensor and configured to at least facilitate: applying the torque for the one or more wheels; determining a wheel slip difference between the second wheel slip and the first wheel slip; and estimating a characteristic of a surface of a road in which the vehicle is travelling based at least in part on the wheel slip difference and the magnitude of the applied torque.