64 results about "Self aligning torque" patented technology

An electric power steering apparatus has a steering mechanism SM having universal joints 4, 6 in a torque transmitting system, a steering toque detecting unit 14, a steering angle detecting unit 18, a torque fluctuation detecting unit 43 for detecting a torque fluctuation due to the crossing angle α in the universal joints 4, 6 on the basis of the steering angle θ detected by the steering angle detecting unit 18 and any one of the steering torque T detected by the steering torque detecting unit, a current command value It and self-aligning torque SAT; and a current command value correcting unit 44 for correcting the current command value on the basis of the torque fluctuation detected by the torque fluctuation detecting unit 43 and the steering angle θ detected by the steering angle detecting unit 18.

A first ECU 30 detects a steering torque applied to a steering system, estimates a self-aligning torque generated in a front wheel on the basis of the steering torque, and estimates a side force for the front wheel on the basis of lateral acceleration and a yaw rate. The first ECU 30 estimates a grip factor ε for the front wheel on the basis of a change of the self-aligning torque to the side force. The first ECU 30 judges whether the grip factor is below a second OS (oversteer) start threshold value. A second ECU 40 controls the transfer ratio according to the vehicle state when the grip factor is less than the second OS start threshold value.

An electric power steering apparatus includes a first torque command value calculating means that calculates a first torque command value on the basis of steering torque detected by a steering torque detecting means, a malfunction torque detecting means that detects malfunction of the steering torque detecting means, and a self aligning torque estimating means that estimates self aligning torque transmitted from a road surface to a steering mechanism, and the apparatus further includes a second torque command value calculating means that calculates a torque command value on the basis of the self aligning torque estimated by the self aligning torque estimating means, and an switching means that selects the second torque command value calculating means.

A system and method for converting a vehicle steering angle command to a vehicle steering torque command for a vehicle steering system in a vehicle. The method estimates a self-aligning torque that defines the torque that maintains a vehicle steering wheel at a neutral steering position or to a position that makes no slip angle at the road wheel, applies known total steering torque commands to the steering system at a plurality of sample time steps where the known steering torque commands include the self-aligning torque, and measures a vehicle steering angle at each time step. The method then models the steering system of the vehicle using the torque commands, the measured steering angles, a system delay and a plurality of unknown parameters.

A first ECU 30 detects a steering torque applied to a steering system, estimates a self-aligning torque generated in a front wheel on the basis of the steering torque, and estimates a side force for the front wheel on the basis of lateral acceleration and a yaw rate. The first ECU 30 estimates a grip factor ε for the front wheel on the basis of a change of the self-aligning torque to the side force. The first ECU 30 judges whether the grip factor is below a second OS (oversteer) start threshold value. A second ECU 40 controls the transfer ratio according to the vehicle state when the grip factor is less than the second OS start threshold value.

A grip factor estimating apparatus includes a steering torque detecting unit M1, and an assist torque detecting unit M2. When a self-aligning torque estimating unit M6 estimates self-aligning torque generated in front wheels on the basis of detection result of the detecting unit, the quantity of influence of longitudinal force on self-aligning torque is removed on the basis of longitudinal force acting on the front wheels and estimated by a longitudinal force estimating unit M15 and a front wheel slip angle estimated by a front wheel slip angle estimating unit M9y. A grip factor estimating unit M12 estimates the grip factor of the front wheels on the basis of change in self-aligning torque in accordance with the side force.

In the electric power steering apparatus which controls a motor that gives a steering assisting force to a steering mechanism based on an electric current controlling value which is computed from a steering assisting command value which has been computed by a computing device based on a steering torque generated in a steering shaft and an electric current value of the motor, provided are a self-aligning torque estimating section which estimates a self-aligning torque by a disturbance observer constitution and a steering torque feedback section which performs definition of a steering reaction force based on a self-aligning torque estimated value which has been estimated by the self-aligning torque estimating section and feeds the steering reaction force back to the steering torque.

A motor-driven power steering apparatus is provided with a self-aligning torque computing means for computing a self-aligning torque based on of a steering angle and a vehicle speed, a friction torque computing means for computing a friction torque in accordance with a steering angle change from a steering angular velocity, an apparent steering torque computing means for computing an apparent steering torque from the friction torque and a steering torque, and a steering torque feedback control means for driving and controlling an assist motor in such a manner that a difference between the self-aligning torque and the apparent steering torque becomes 0.

In a steering control device, a road surface reaction force torque calculation module (52) uses a vehicle speed, steering angle, and vehicle model to calculate a caster-trail-caused torque, a self-aligning torque, and a road surface reaction force torque. A reaction force command current calculation module (53) uses the road surface reaction force torque and the vehicle speed to calculate a reaction force command current.

A tire state estimator includes a lateral force upper limit estimating section, a lateral force estimating section, and a tire slip angle estimating section. The lateral force upper limit estimating section calculates an estimated tire lateral force upper limit, on a basis of an estimated tire slip angle and a measured tire self aligning torque. The lateral force estimating section calculates an estimated tire lateral force, on a basis of the estimated tire lateral force upper limit calculated by the lateral force upper limit estimating section and the estimated tire slip angle. The tire slip angle estimating section calculates the estimated tire slip angle, on a basis of the estimated tire lateral force calculated by the lateral force estimating section and a measured vehicle state.

An in-lane drive assist device controls a turning amount of a turning unit that is mechanically detached from a steering unit-based on a steering amount of a steering unit when a lane deviation is determined to be absent. The in-lane drive assist device controls the turning amount based on a drive assist turning amount for generating a yaw moment to return a vehicle into a lane while the steering reaction force applied to the steering unit is controlled based on a target steering reaction force corresponding to a steering reaction force characteristic that is set so that a self-aligning torque increases as the steering reaction force increases when a lane deviation is determined to be present, and the steering reaction force characteristic is offset in a direction in which an absolute value of the steering reaction force increases as a lateral position of the vehicle approaches a white line.

A method for estimation of the maximum grip coefficient on the basis of knowledge of the forces and the self-alignment torque which are generated in the contact area of a tire, includes the steps of:selecting a plurality of fixed points in space, which lie at different azimuths along the circumference in at least one sidewall of the tire,carrying out a corresponding number of measurements of circumferential distance variation (extension or contraction) at these fixed points when the tire is rolling on the road,processing the measurement signals so as to extract the three components of a resultant of forces which are exerted by the road on the contact area of a tire and the self-alignment torque generated by the tire from them,processing the evaluation signals of the three components of a resultant of forces which are exerted by the road on the contact area of a tire and of the self-alignment torque generated by the tire so as to extract the said grip coefficient μ from them.

A method for estimation of the maximum grip coefficient on the basis of knowledge of the forces and the self-alignment torque which are generated in the contact area of a tire, includes the steps of: selecting a plurality of fixed points in space, which lie at different azimuths along the circumference in at least one sidewall of the tire, carrying out a corresponding number of measurements of circumferential distance variation (extension or contraction) at these fixed points when the tire is rolling on the road, processing the measurement signals so as to extract the three components of a resultant of forces which are exerted by the road on the contact area of a tire and the self-alignment torque generated by the tire from them, processing the evaluation signals of the three components of a resultant of forces which are exerted by the road on the contact area of a tire and of the self-alignment torque generated by the tire so as to extract the said grip coefficient μ from them.

A steering controller for an electric power steering device 110 includes a base signal computing part 51 for computing a base signal DT in accordance with at least the steering torque; a damper compensation signal computing part 52 for computing a damper compensation signal in accordance with an angular velocity of an electric motor 4 or a speed of steering wheel turn; and an inertia compensation signal computing part 53 for compensating inertia and viscosity in the steering unit. The electric motor is driven by a target signal IM1 obtained by compensating the base signal with a damper compensation signal and an inertia compensation signal, to provide a steering auxiliary force. The target signal of the auxiliary torque is compensated so that a difference between a reference self-aligning torque of front wheel in a front wheel steering vehicle and a self-aligning torque of front wheel in an all-wheel steering vehicle is provided to a driver as a responsive feeling from the steering torque.

There is provided a control system for an electronic power steering. The control system includes: a SAT estimating portion for estimating a self aligning torque (SAT) of a vehicle by inputting an angular velocity and an angular acceleration of a motor, a steering torque, and a current command value; and a motor current correction value calculating portion for deciding a running state of the vehicle based on a SAT estimation value estimated by the SAT estimating portion, a vehicle speed, and a steering angle, and correcting the current command value by calculating a motor current correction value based on the SAT estimation value in accordance with the running state. According to this configuration, an offset torque can be always corrected precisely irrespective of a road surface situation or a driving condition such as a straight line running, and thus a comfortable steering performance can be attained by lessening driver's fatigue.

Method of determining at least one of the characteristics selected from: the three components of a resultant of forces which are exerted by the road on the contact area of a tire and the self-alignment torque generated by the tire, in which the said characteristic is derived from at least one measurement of the shear stresses at two fixed points in space, which are each situated in one of the beads.

A computed SAT value SATa is computed, and an estimated SAT value SATb is estimated from lateral force. A grip loss level “g” is computed from difference between the computed self aligning torque value SATA and the estimated SAT value SATb. Torque correction value ΔT which becomes greater with an increase in grip loss level “g” and an increase in angular speed ω is set in accordance with the grip loss level “g” and the angular speed ω of an electric motor 12 serving as corresponding steering angular speed. The corresponding torque correction value ΔT is subtracted from the current command value Itv responsive to the steering torque T and the vehicle speed V, thereby correcting the current command value Itv. The thus-corrected current command value Itv is taken as a steering assist command value Im, and the electric motor 12 is driven based on the steering assist command value.

The present invention relates to a method and apparatus for controlling electric power steering. In particular, the present invention provides a power steering control method that includes: a breakdown detection step of detecting whether a torque sensor has broken down; an information reception step of receiving steering angle information and vehicle speed information in the case in which the torque sensor has broken down; a compensation target value calculation step of calculating a self-aligning torque, and a damping force, an inertial force, and a frictional force of an electric power steering apparatus by using one or more of the steering angle information and the vehicle speed information; and a current control step of calculating a steering assist force based on the compensation target value and controlling the supply of a motor control current that corresponds to the steering assist force, and an apparatus for the same.

The invention discloses a yawing motion control method of a four-wheel distribution type drive coach, and relates to the technical field of vehicle control. A layered control method is adopted, the upper layer is a motion tracking layer, steering response of a steady state of the vehicle is calculated by adopting a non-linear vehicle model and the reference understeer degree, meanwhile, a road attachment condition limiting value is adopted for constraint, and steady-state lateral force response and tire self-aligning torque response are calculated with a magic tire formula according to slip angle response at the steady state and vertical load change; needed additional yawing moment is calculated with a yawing motion balance equation; a lower layer is an actuator control layer, and generalized control force is reasonably distributed to four drive motors with an optimization algorithm through combination with the current driving condition; finally, offline distribution calculation results of different vehicle parameters needed on different upper layers are stored and looked up offline, four driving wheels are subjected to torque distribution according to road attachment conditions, yawing motion of the vehicle is controlled, and driving stability is guaranteed.

A method for determining a state of health (SOH) value for an electric power steering (EPS) system in a vehicle includes estimating a first Self-Aligning Torque (SAT) value using a tire dynamics model, which includes modeled dynamics in the linear region of a lateral force acting on the vehicle tires. The method also includes estimating a second SAT value using an extended state observer and nominal parameters for the EPS system, and calculating a variance between the first and second SAT values. The controller monitors a progression of the calculated variance over a calibrated interval using the controller to thereby determine the SOH value, and automatically executes a control action using the SOH value. An EPS system for a vehicle includes a steering wheel, torque and angle sensors, a rack and pinion assembly, a steering motor, and the controller. A vehicle is also disclosed having the same controller.

An SAT estimating section estimates self-aligning torque (SAT) on the basis of a steering torque, which is detected by a steering torque detecting section, and an assist torque, which is detected by an assist torque detecting section. An SAT model value computing section computes an SAT model value by using an integrated slip angle αI. An SAT ratio / drift amount computing section computes, by on-line identification, a ratio (SAT ratio) of the SAT to the SAT model value, and a drift amount of a lateral acceleration sensor.

A method for tire parameter derivation, tire cornering characteristic calculation and tire design is used with a tire dynamic model constituted by using a plurality of tire dynamic element parameters including stiffness and friction coefficient and parameter defining a distribution of contact pressure of the tire. The parameters and tire cornering characteristic are derived by using the combined sum of squared residuals being obtained by weighted addition of a first sum of squared residuals of lateral force and a second sum of squared residuals of self-aligning torque. The tire dynamic model is a model for calculating a lateral force and for calculating a self-aligning torque separately as a lateral force-based torque component generated by the lateral force applied on a contact patch of the tire and a longitudinal force-based torque component generated by a longitudinal force applied on the contact patch of the tire.

Values of multiple tire dynamic element parameters are set for a tire dynamic model constructed using the tire dynamic element parameters for calculating a tire axial force and a self-aligning torque under a given slip ratio. Next, the values of the tire axial force and the self-aligning torque are calculated using the tire dynamic model and output. The tire dynamic model allows a center position of a contact patch thereof against a road surface to move in accordance with a longitudinal force that occurs as the tire axial force when a slip ratio in a braking / driving direction is given so that a position of the contact patch moves in a longitudinal direction due to the longitudinal force. When designing a vehicle or when designing a tire, the tire dynamic model is used.

In an electric power steering system installed in a vehicle and designed to generate, by a motor, assist torque for assisting the driver's turning effort of the steering wheel, a self-aligning torque determiner determines a value of self aligning torque applied to the vehicle. A commanded-value generator determines a value of an assist ratio based on a predetermined relationship between a variable of the self aligning torque and a variable of the assist ratio. The assist ratio represents a ratio of share of torque by the motor for compensating the self aligning torque. The commanded-value generator generates, based on the self aligning torque and the value of the assist ratio, a commanded value for the assist torque. An assist torque determiner determines the assist torque based on the commanded value for the assist torque generated by the commanded-value generator.

A motor-driven power steering apparatus is provided with a self-aligning torque computing means for computing a self-aligning torque based on of a steering angle and a vehicle speed, a friction torque computing means for computing a friction torque in accordance with a steering angle change from a steering angular velocity, an apparent steering torque computing means for computing an apparent steering torque from the friction torque and a steering torque, and a steering torque feedback control means for driving and controlling an assist motor in such a manner that a difference between the self-aligning torque and the apparent steering torque becomes 0.

A grip factor estimating apparatus includes a steering torque detecting unit M1, and an assist torque detecting unit M2. When a self-aligning torque estimating unit M6 estimates self-aligning torque generated in front wheels on the basis of detection result of the detecting unit, the quantity of influence of longitudinal force on self-aligning torque is removed on the basis of longitudinal force acting on the front wheels and estimated by a longitudinal force estimating unit M15 and a front wheel slip angle estimated by a front wheel slip angle estimating unit M9y. A grip factor estimating unit M12 estimates the grip factor of the front wheels on the basis of change in self-aligning torque in accordance with the side force.

The invention provides an electric power steering apparatus which can well maintain the steering feel of a steering disc in turning and a steering effort assist controlling apparatus. An electric power steering apparatus (11) provides a steering assist force to the steering system of a vehicle by controlling driving of an assist motor in accordance with a steering force acting on the steering wheel. The electric power steering apparatus (11) includes a yaw rate sensor (55) that obtains a measured yaw rate of the vehicle, a vehicle speed sensor (53) that detects the speed of the vehicle, a steering angle sensor (13) that detects the steering angle of the steering wheel, and a torque estimating apparatus (77) that estimates a self-aligning torque on the basis of the vehicle speed and data having a smaller absolute value among the measured yaw rate and the steering-angle standard yaw rate and that corrects the steering assist force on the basis of the estimated self-aligning torque.

[Object]An electric power steering apparatus capable of returning the steering wheel to a steering wheel neutral position even in case of failure of a steering angle sensor.[Solution] In performing a control action whereby the steering wheel is returned to a neutral position according to the steering angle and yaw rate, the gain of the yaw rate sensor (13) is amplified if a failure in the steering angle sensor (12) is detected, and the damping gain of a damping compensation unit (23) is reduced if failure in at least one of the sensors is detected. Thereby, the steering wheel (1) can return to the neutral position by producing a stronger returning force based on an amplified detection value even if the real yaw rate is small, and the damping component acting on the returning force can be reduced so that the self-aligning torque is enabled to return the steering wheel to the neutral position.

A steering control device set a steering reaction force characteristic to coordinates so that the self-aligning torque increases as the steering reaction force increases. Upon applying a steering reaction force corresponding to the self-aligning torque to a steering unit based on the steering reaction force characteristic to offset the steering reaction force characteristic at coordinates more in a direction in which an absolute value of the steering reaction force increases as a lateral position of a host vehicle approaches to a white line, the offset of the steering reaction force characteristic is suppressed when a turn signal operation is started while suppression of the offset of the steering reaction force characteristic is released when the turn signal operation is ended so that an absolute value of an increase gradient when releasing suppression of the offset becomes smaller than an absolute value of a decrease gradient when suppressing the offset.