A system and a method of controlling a motor-driven power steering are disclosed. A basic steering torque assist compensation is made according to a LOAM compensation logic under a steering condition such as steering of a steering wheel and holding of the steering wheel after steering, and an additional steering torque compensation is made to reduce the basic steering torque assist compensation amount when returning the steering wheel to the center or releasing the steering wheel in a restoring direction, thereby reducing steering effort felt by a driver when returning the steering wheel to the center or releasing the steering wheel in the restoring direction, and thus maintaining proper steering effort when a torque sensor of a high-performance vehicle fails.

A steer-by-wire steering apparatus is for turning steerable wheels of a vehicle. The steering apparatus includes a steering wheel rotatable about a steering axis by a vehicle operator to effect turning of the steerable vehicle wheels. A first sensor is for determining a steering torque applied to the steering wheel by the vehicle operator. A power steering system is configured to turn the steerable vehicle wheels in accordance with the determined steering torque. The power steering system has a second sensor for sensing a position of a portion of the power steering system. A motor is operably connected to the steering wheel and controllable to apply a force to the steering wheel. The motor is controlled in accordance with the sensed position.

Methods, apparatus, systems and articles of manufacture are disclosed. An example vehicle disclosed herein includes a steering assist system, a steering wheel, and a steering controller to detect a request to move the steering wheel of the vehicle to a first rotational position, the steering wheel having a second rotational position, actuate, via the steering assist system, the steering wheel towards the first rotational position, determine, based on a relationship between a first parameter and a second parameter, a third rotational position, the third rotational position having an angular offset from the first rotational position, the first parameter corresponding to a position of the steering system, the second parameter corresponding to a load on the steering system, and in response to reaching the third rotational position, disengage the steering assist system, the disengagement causing the steering wheel to rotate to the first rotational position.

[Problem] An object of the present invention is to provide an electric power steering apparatus that constitutes a control system based on a physical model, constitutes a model following control that an output (a distance to a rack end) of a controlled object follows-up to a reference model, suppresses the occurrences of a noisy sound and a shock force at an end hitting without giving any uncomfortable steering feeling to a driver, and is capable of smoothly steering.

[Means for solving the problem] In the electric power steering apparatus that calculates a first current command value based on at least a steering torque and performs an assist-control of a steering system by driving a motor based on the first current command value, the apparatus comprises a configuration of a model following control comprising a feed-back control section including a viscoelastic model as a reference model within a predetermined angle at front of a rack end, wherein the configuration of the model following control comprises a feed-back control section, and the model following control has a noise-reducing function to reduce a noise so as to suppress a rack end hitting.

[Problem]

An object of the present invention is to provide an electric power steering apparatus for calculating a front-wheel estimated steering angle based on right and left front wheel speeds, calculating a rear-wheel estimated steering angle based on right and left rear wheel speeds, calculating a 4-wheel estimated steering angle by using the front-wheel estimated steering angle and the rear-wheel estimated steering angle, and correcting a probability of the 4-wheel estimated steering angle or correcting an output of a control with the 4-wheel estimated steering angle by using the front-wheel estimated steering angle, the rear-wheel estimated steering angle and 4 wheel speeds, thereby preventing an irregular output.

[Means for Solving]

The present invention is an electric power steering apparatus which has a steering torque sensor to detect a steering torque, a current command value calculating section to calculate a current command value based on the steering torque, a motor to apply an assist torque, and a motor driving control section to drive and control the motor, comprises: a control function with an input steering angle; and a steering angle estimating/calculating section to calculate a front-wheel estimated steering angle and a rear-wheel estimated steering angle based on a 4 wheel speeds and calculate a 4-wheel estimated steering angle, wherein the 4-wheel estimated steering angle is used for a steering angle control.

The present application discloses a control apparatus for electric power steering, including: a gain determination portion configured to determine a first assist gain in correspondence to a steering torque acting on a steering shaft when a driver rotates a steering wheel; and a gain adjuster which adjusts the first assist gain in response to a change in a rotation direction of the steering wheel to generate a second assist gain. The gain adjuster generates the second assist gain so as to reduce a difference between a first torque, which is required of the driver rotating the steering wheel to a predetermined rotation position, and a second torque, which is required of the driver holding the steering wheel at the rotation position.

The present application discloses a control apparatus for electric power steering, including: a gain determination potion configured to determine a first assist gain in correspondence to a steering torque acting on a steering shaft when a driver rotates a steering wheel; and a gain adjuster which adjusts the first assist gain in response to a change in a rotation direction of the steering wheel to generate a second assist gain. The gain adjuster generates the second assist gain so as to adjust a difference between a first torque, which is required of the driver rotating the steering wheel to a predetermined rotation position, and a second torque, which is required of the driver holding the steering wheel at the rotation position.

A method for determining a neutral position of a MDPS (Motor Driven Power Steering) system may include: determining, by a controller, whether a vehicle is driving; determining, by the controller, whether a steering torque is smaller than a preset break point on a boost curve, when the vehicle is driving; and determining, by the controller, that the vehicle is in a neutral state, when the steering torque is smaller than the preset break point on the boost curve.

The vehicle control system is applied as a system of a vehicle mounted with an EPS device having an electric motor driven to control the steering angle. The vehicle control system includes a controller configured to perform steering control for controlling an energization of the electric motor to control the steering angle of the wheels. When the wheels are held after being steered by a specific steering in the steering control, the controller performs a steering return process in which the wheels are turned back and held in a direction opposite to a steering direction of the specific steering. And during a stationary steering-holding in which the steering angle is held and the vehicle is stopped, the controller performs an energization suppression process for reducing energization to the electric motor to be smaller than the energization before the stationary steering-holding.

Restriction values (upper limit and lower limit) for an assist control amount are set individually for each of state amounts including steering torque τ used to compute the assist control amount. A value obtained by summing such restriction values is set as a final restriction value for the assist control amount. Even though the assist control amount with an abnormal value is computed, the assist control amount is restricted to an appropriate value by the final restriction value. In addition, a transition is made from a primary assist control amount which is restricted to a secondary assist control amount computed separately from the primary assist control amount at the timing when a certain time elapses since the assist control amount is restricted. As the steering torque τ is increased, the speed of transition from the primary assist control amount to the secondary assist control amount is increased.