A method for estimating a friction between a road surface and a tire of a steered wheel of a vehicle. The steered wheel being fit with dynamic steering. The vehicle includes a steering wheel and a set of sensors comprising wheel end sensors and steering wheel sensors configured to measure signals corresponding to a set of parameters., The steering wheel parameters comprising at least a steering wheel torque and a steering wheel angle. The method comprising the following steps implemented by the electronic control unit collect the signals, corresponding to the set of parameters, measured by the sensors during a period of time; process, by the signal processing module, the signals collected to provide processed signal data provide the processed signal data as input to the wheel end friction estimation model, the wheel end friction estimation model being configured to output a friction estimation of the friction between the road surface and the tire of the wheel.

A control device for a steer-by-wire type vehicle calculates a target turn angle being represented as a function of a steering angle of a steering wheel, and controls a turning device such that a turn angle of a wheel becomes the target turn angle. A variation range of the steering angle includes: an effective steering range in which the steering angle is an effective maximum steering angle or smaller; and an adjustment steering range in which the steering angle is between the effective maximum steering angle and a predetermined maximum steering angle. The target turn angle calculated according to the effective maximum steering angle is an effective maximum turn angle. The control device variably sets the function according to a road surface condition such that the effective maximum turn angle in a case of a low-μ condition is smaller than that in a case of a high-μ condition.

A method for estimating a longitudinal force difference ΔFx acting on steered axle wheels of a vehicle, the method comprising obtaining data from the vehicle related to an applied steering torque M.sub.steer associated with the steered axle wheels, obtaining a scrub radius value r.sub.s associated with the steered axle wheels, and estimating the longitudinal force difference ΔFx, based on the obtained data and on the scrub radius r.sub.s, as proportional to the applied steering torque M.sub.steer and as inversely proportional to the scrub radius r.sub.s.

A system and a method of controlling a power steering system of a vehicle are provided. A control system includes a control module operable to determine a rack force of the vehicle based on at least one of a motor velocity, a driver torque and a motor torque, determine a plurality of modeled rack forces based on a roadwheel angle and a vehicle speed, compare the rack force to the plurality of modeled rack forces to generate a friction level included in a control signal, and send the control signal to the power steering system.

A system for determining driver torque includes a rack torque estimator module that determines an estimated rack torque value based on a motor angle, and a motor velocity. The system further includes a driver intent detection module that computes a disturbance torque scaling factor based on the estimated rack torque value. The system further includes a blend module that generates a motor torque assist command based on a scaled value of the estimated rack torque value using the disturbance torque scaling factor.

A method and system for estimating surface roughness of a ground for an off-road vehicle to control steering of a vehicle, an implement, or both, comprises detecting motion data of an off-road vehicle traversing a field or work site during a sampling interval. A first sensor is adapted to detect pitch data of the off-road vehicle for the sampling interval to obtain a pitch acceleration. A second sensor is adapted to detect roll data of the off-road vehicle for the sampling interval to obtain a roll acceleration. An electronic data processor or surface roughness index module determines or estimates a surface roughness index based on the detected motion data, pitch data and roll data for the sampling interval. The surface roughness index can be displayed on the graphical display to a user or operator of the vehicle.

In one embodiment, a method for steering system integrity testing includes positioning the vehicle with the second traction wheel within a first constraint; applying mechanical load to the first traction wheel; receiving data corresponding to a steering system operating condition; positioning the vehicle with the first traction wheel within a second constraint; applying mechanical load to the second traction wheel; receiving data corresponding to a steering system operating condition; positioning the vehicle with the first and second traction wheels on respective first and second friction surfaces; applying mechanical load to the first and second traction wheels; receiving data corresponding to a steering system operating condition; transmitting the data to a processor; and determining, via the processor, a health status of the steering system based on the data.

A steering control device capable of transmitting road surface state to a driver is provided. An ideal vehicle model computes first spring reaction force torque based on a target pinion angle and second spring reaction force torque based on at least lateral acceleration as components of a spring component of a steering assist force. The ideal vehicle model combines the first and second spring reaction force torques with specified proportions of use to compute the spring component. The ideal vehicle model decides the proportions of use of the first and second spring reaction force torques on the basis of a distribution gain set in accordance with the difference value between the first and second spring reaction force torques. The ideal vehicle model increases the proportion of use of the second spring reaction force torque as the difference value between the first and second spring reaction force torques is increased.

A method determines a roadway condition using steering actuators, wherein at least two steering actuators are arranged on each vehicle wheel. Measurement variables of the first and second steering actuators are sensed. The sensed measurement variables of the two steering actuators are compared with one another and, an inhomogeneity signal is determined from the deviation between the sensed measurement variables of the two steering actuators. If the inhomogeneity signal lies within a tolerance range, a homogeneous roadway condition exists. If the inhomogeneity signal lies outside the tolerance range, an inhomogeneous roadway condition exists.

A method for controlling an electric power steering apparatus, the electric power steering apparatus and a vehicle equipped with the same. The method includes detecting an upper-side angle of a torsion bar; detecting a lower-side angle; setting an angle target value of an opposite side by using one of the upper-side angle or the lower-side angle; detecting an actual angle of the opposite side; and performing an angle follow-up feedback control based on a deviation between the angle target value and the actual angle.