# US 11,110,956 B2 · Quadrant based friction compensation for tire load estimation in steering systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,110,956 B2 - Document ID: US11110956B2 - Status: Granted - Kind: B2 - Application number: 16/276,359 - Filed: 2019-02-14 - Published: 2019-08-22 - Granted: 2021-09-07 - Earliest claimed: 2018-02-22 - Assignees: Steering Solutions IP Holding Corporation - Applicants: Steering Solutions IP Holding Corporation - Inventors: Mariam Swetha George; Tejas M. Varunjikar - Web page: https://patentgrep.com/patent/US11110956B2 ## CPC - B62D 5/0463: {calculating assisting torque from the motor based on driver input} - B62D 5/006: {power actuated} - B62D 5/0481: {monitoring the steering system, e.g. failures} - B62D 6/007: {adjustable by the driver, e.g. sport mode} - B62D 6/008: {Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications} - G01M 17/02: Tyres - B62D 5/0409: {Electric motor acting on the steering column} - 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) - G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR ## Abstract According to one or more embodiments a control system for a steering system, includes a control module that estimates a tire load by performing a method that includes receiving, as an input torque, motor-torque that is generated by a motor of the steering system. The method further includes computing an efficiency factor for a gear of the steering system based on the input torque and a motor velocity. The method further includes adjusting the input torque by scaling the input torque with the efficiency factor. The method further includes estimating the tire load using the adjusted input torque as an input to a state observer for the steering system. ## Claims ### Claim 1 A control system for a steering system, comprising: a control module operable to estimate a tire load by performing a method comprising: receiving, as an input torque, motor-torque that is generated by a motor of the steering system; computing an efficiency factor for a gear of the steering system based on the input torque and an angular motor velocity; adjusting the input torque by scaling the input torque with the efficiency factor; and estimating the tire load based on the adjusted input torque. ### Claim 2 (depends on 1) The control system of claim 1, wherein the input torque further comprises a handwheel torque that is added into the motor-torque. ### Claim 3 (depends on 1) The control system of claim 1, further comprising: estimating a static friction in the steering system based on the angular motor velocity and the adjusted input torque; computing a second adjusted torque by subtracting the static friction from the adjusted torque; and using the second adjusted torque as the input to a plant model. ### Claim 4 (depends on 1) The control system of claim 1, wherein computing the efficiency factor for the gear is based on detecting an operational quadrant of the gear with respect to the input torque and the angular motor velocity. ### Claim 5 (depends on 1) The control system of claim 1, wherein computing the efficiency factor comprises: determining a first value by multiplying the input torque and the angular motor velocity; and selecting the efficiency factor from among a forward efficiency factor and a backward efficiency factor based on a comparison of the first value with a predetermined threshold. ### Claim 6 (depends on 5) The control system of claim 5, wherein computing the efficiency factor further comprises: computing uv, where u is the efficiency factor and v is the first value. ### Claim 7 (depends on 5) The control system of claim 5, wherein the backward efficiency factor is determined based on the angular motor velocity. ### Claim 8 (depends on 1) The control system of claim 1, wherein the steering system is a steer by wire system, and the control module is further operable to compute a handwheel torque for providing driver feedback based on the estimated tire load. ### Claim 9 (depends on 1) The control system of claim 1, wherein the control module is further operable to compute a disturbance adjustment torque command to generate a corresponding amount of torque using the motor of the steering system, the disturbance adjustment torque command computed based on the estimated tire load. ### Claim 10 A method to estimate a tire load in a steering system, the method comprising: receiving, as an input torque, motor-torque that is generated by a motor of the steering system; computing an efficiency factor for a gear of the steering system based on the input torque and an angular motor velocity; adjusting the input torque by scaling the input torque with the efficiency factor; and estimating the tire load based on the adjusted input torque. ### Claim 11 (depends on 10) The method of claim 10, wherein the input torque further comprises a handwheel torque that is added into the motor-torque. ### Claim 12 (depends on 10) The method of claim 10, further comprising: estimating a static friction in the steering system based on the angular motor velocity and the adjusted input torque; computing a second adjusted torque by subtracting the static friction from the adjusted torque; and using the second adjusted torque as the input to a plant model. ### Claim 13 (depends on 10) The method of claim 10, wherein computing the efficiency factor for the gear is based on detecting an operational quadrant of the gear with respect to the input torque and the angular motor velocity. ### Claim 14 (depends on 10) The method of claim 10, wherein computing the efficiency factor comprises: determining a first value by multiplying the input torque and the angular motor velocity; selecting the efficiency factor from among a forward efficiency factor and a backward efficiency factor based on a comparison of the first value with a predetermined threshold; and computing uv, where u is the efficiency factor and v is the first value. ### Claim 15 (depends on 14) The method of claim 14, wherein the backward efficiency factor is determined based on the angular motor velocity. ### Claim 16 A steering system comprising: a steering gear; a processor configured to compute a tire load estimate by performing a method comprising: receiving, as an input torque, motor-torque that is generated by a motor of the steering system; computing an efficiency factor for a gear of the steering system based on the input torque and an angular motor velocity; adjusting the input torque by scaling the input torque with the efficiency factor; and estimating the tire load based on the adjusted input torque. ### Claim 17 (depends on 16) The steering system of claim 16, wherein the input torque further comprises a handwheel torque that is added into the motor-torque. ### Claim 18 (depends on 16) The steering system of claim 16, the method further comprising: estimating a static friction in the steering system based on the angular motor velocity and the adjusted input torque; computing a second adjusted torque by subtracting the static friction from the adjusted torque; and using the second adjusted torque as the input to a plant model. ### Claim 19 (depends on 16) The steering system of claim 16, wherein computing the efficiency factor comprises: determining a first value by multiplying the input torque and the angular motor velocity; and selecting the efficiency factor from among a forward efficiency factor and a backward efficiency factor based on a comparison of the first value with a predetermined threshold; and computing uv, where u is the efficiency factor and v is the first value. ### Claim 20 (depends on 19) The steering system of claim 19, wherein the backward efficiency factor is determined based on the angular motor velocity.