Abstract: An electric power steering system is provided which is capable of providing a favorable steering feeling without using compensation logics such as of inertia compensation and friction compensation. The electric power steering system includes road-noise suppression control means (213) for controlling a steering assist motor (9) in a manner to damp torque transmission in a higher frequency region representing road noises than a frequency region representing road information. A friction value of a steering mechanism (A) is decreased enough to allow the intrinsic vibrations of the steering mechanism (A) to appear. Rotor inertia of the steering assist motor (9) is set to a value small enough to allow the frequencies of the intrinsic vibrations to be present in the frequency region where the torque transmission is damped by the road-noise suppression control means (213).

Abstract: An electric power steering apparatus (1, 64) comprises a housing (10) for supporting a steer shaft (9) for axial slide movement, a speed reduction mechanism (23), and a motion converting mechanism (24, 76). The housing (10) includes a plurality of split housings (36, 37; 36, 37A, 70) connected to each other. The speed reduction mechanism (23) includes an output gear (22) surrounding the steer shaft (9). The motion converting mechanism (24, 76) includes a rotary sleeve (28) surrounding the steer shaft (9) and rotatable integrally with the output gear (22) and converts the rotation of the rotary sleeve (28) into axial movement of the steer shaft (9). The rotary sleeve (28) is rotatably supported by first and second bearings (30, 31) disposed on opposite sides of the output gear (22). The split housings (36, 37; 36, 37A, 70) include main split housings (37, 37A) rotatably supporting an input gear (21) and supporting the first and second bearings (30, 31).

Abstract: A storage part stores an initial sum, which is obtained by summing a steering angle of a steering wheel and a rotational angle of an electric actuator before checking of unlocking of a transmission ratio variable mechanism by a computer part. The computer part determines that the storage part is abnormal when a sum, which is obtained by summing the steering angle of the steering wheel and the rotational angle of the electric actuator after the checking of the unlocking of the transmission ratio variable mechanism by the computer part, differs from the initial sum, which is retrieved from the storage part.

Abstract: In a motor-driven power steering apparatus which converts a rotation of an electric motor into a linear stroke of a rack shaft by a power transmission mechanism, and steers a wheel coupled to the rack shaft, there is provided an automatic neutral restoring means for judging a vehicle stop and a manual steering rest, and rotating the electric motor as to restore a detected steering angle of a steering angle sensor to a neutral position so as to execute an automatic steering, when the steering angle is out of the neutral position.

Abstract: A vehicle steering apparatus includes a steering member; a steering shaft connected to the steering member; a torque sensor for detecting a steering torque inputted into the steering member; and an electric motor for generating power that is transmitted to the steering shaft based on the steering torque detected by the torque sensor. The electric motor includes an annular rotor and an annular stator. The annular rotor includes an annular rotor core which coaxially surrounds the steering shaft and is rotatable together with a part of the steering shaft. An annular accommodation space is formed between an outer circumference of the steering shaft and an inner circumference of the annular rotor core, and at least a part of the torque sensor is disposed within the annular accommodation space.

Abstract: Provided are an electric power steering device which is capable of determining a failure without using a motor current, and an electric power steering device which removes any motor current detecting unit for detecting the motor current such as a shunt resistor, and suppresses the heat generation and the power loss in the device, thereby making it possible to realize the downsized device, a reduction in the costs, and the higher efficiency. An electric power steering device according to the present invention includes: a motor coupled with a steering system; a drive control unit for controlling a drive of the motor; a motor impression voltage detecting unit for detecting an applied voltage of the motor; and an abnormality determining unit for determining abnormality based on a comparison result of the detected motor impression voltage and an output voltage of the drive control unit.

Abstract: In a power steering device employing a hydraulic power cylinder, a motor-driven pump, and a driving power source for the motor, a power steering control system is configured to electrically connected to at least the motor and the power source for controlling a driving state of the motor and a power source voltage of the power source. The power steering control system includes a motor control circuit that generates a motor driving signal, whose command signal value is determined based on a steering assist force applied through the power cylinder to steered road wheels, a booster circuit that boosts the power source voltage, a motor angular acceleration detection circuit that detects or estimates a motor angular acceleration, and a booster-circuit control circuit that controls, responsively to the motor angular acceleration, switching between operating and non-operating states of the booster circuit.

Abstract: Disclosed is an electric power steering apparatus including a steering shaft connected to a steering wheel of an automobile; a reduction shaft adapted to engage with the steering shaft and rotate; a direction sensor having a transmitter and a receiver; a rotation member formed on an end of the reduction shaft and positioned between the transmitter and the receiver; a motor for supplying steering power; a motor position sensor positioned on the motor to sense a rotational angle of a motor shaft; and an electronic control unit adapted to receive electric signals from the direction sensor and the motor position sensor, respectively, and calculate a steering angle. The electric power steering apparatus is equipped with a steering angle sensor adapted to sense an absolute steering angle using a direction sensor for sensing the rotational direction of a steering shaft and a motor position sensor for sensing the rotational position of a motor shaft. This reduces the manufacturing cost of the steering apparatus.

Abstract: The pressure detection device includes a buffer member deformable by a pressure change, including one or more magnets, and a sensor assembly including one or more magnetic sensors to detect a variation of a magnetic field accompanied by deformation of the buffer member.

Abstract: A booster includes a booster circuit and a microcomputer. The booster circuit outputs an output voltage. The output voltage is obtained by boosting a power supply voltage. The microcomputer controls the output voltage through a feedback control based on the deviation of the output voltage from a target voltage. The microcomputer determines whether the booster is in an initial state based on a start signal or a restart signal. When determining that the booster is in the initial state, the microcomputer corrects the target voltage such that the target voltage gradually increases from the power supply voltage as time elapses until a predetermined period elapses from the start of the initial state.

Abstract: In a vehicle steering control device, a steering torque estimation unit estimates steering torque of a steering wheel based on driving current of an electric actuator; a torque sensor detects the steering torque of the steering wheel; an electric power assist unit is controlled based on the steering torque detected by the torque sensor; and a comparison unit compares the torque detected by the torque sensor with the steering torque estimated by the steering torque estimation unit. The electric power assist unit is controlled based on the estimated steering torque in place of being controlled based on the torque detected by the torque sensor when the torque sensor is judged to be abnormal, based on a comparison.

Abstract: A vehicle steering control system is provided which can appropriately control a steering angle and provide sufficient braking force even when the brake pedal is fully pressed down during cornering thereby causing wheels to lock. When it is determined that the ABS is active during cornering while braking and the vehicle is not traveling in the intended cornering direction, a steering control section computes a front wheel steering angle correction amount for correcting the front wheel steering angle, and added in the intended cornering direction so as to set front wheels in a vehicle traveling direction.

Abstract: An electric power steering control system for a vehicle that has a steering device coupled by a steering assembly to at least one tire steered by the steering device. The control system controls a current in a motor for generating torque applied to the steering assembly. The control system comprises a feed-forward component that generates a torque target signal representative of the torque applied by the motor to the steering assembly. The torque target signal is proportional to a multiplication of a steering torque from the steering device. There is also a sensor component that senses the motor current and provides a motor current signal. A motor control component receives the torque target signal and the sensed motor signal. The motor current signal is driven towards a value wherein the torque target signal is equal to a multiplication factor of the motor current signal.

Abstract: In an electric power steering device, if the temperature of a specific site that increases due to the driving of a steering assist motor exceeds a threshold, the motor current is controlled to be equal to or below a current restriction value. The temperature Toff of the specific site detected when an engine is stopped, and the current restriction value Ioff provided when the engine is stopped are stored into a storage. A temperature difference Ta between the temperature detected when a starter switch is turned on and the temperature Toff is computed. If the temperature of the specific site when the starter switch is turned on is above the threshold, the current restriction value is set to be equal to or above the current restriction value Ioff stored in the storage, according to the temperature difference Ta, over a time following the turning-on of the starter switch.

Abstract: A power assist steering system for a vehicle, especially for a truck or commercial vehicle, is disclosed that includes a mechanical engine-driven power steering pump that pumps hydraulic fluid to a power steering unit, and an electrical pump adapted to pump hydraulic fluid so as to optimize a power steering flow to the power steering unit and to minimize internal pump flow.

Abstract: A materials handling vehicle is provided comprising: a frame comprising an operator's compartment; wheels supported on the frame, at least one of the wheels being a steerable wheel; a steer-by-wire system and control apparatus. The steer-by-wire system is associated with the steerable wheel to effect angular movement of the steerable wheel about a first axis.

Abstract: A materials handling vehicle is provided comprising: a frame comprising an operator's compartment; wheels supported on the frame, at least one of the wheels being a steerable wheel; a steer-by-wire system associated with the steerable wheel to effect angular movement of the steerable wheel about a first axis; and a control apparatus. The steer-by-wire system comprises a control handle capable of being moved by an operator to generate a steer control signal, a selection switch capable of generating one of a first select signal and a second select signal, and a steer motor coupled to the steerable wheel to effect angular movement of the steerable wheel about the first axis. The control apparatus may be coupled to the control handle to receive the steer control signal, coupled to the selection switch to receive the one select signal, and coupled to the steer motor to generate a first drive signal to the steer motor to effect angular movement of the steerable wheel about the first axis.

Abstract: A steering system includes a steering unit which can be configured to convert an operation input to an input shaft into an arbitrary amount of rotation or an arbitrary turning force and output the arbitrary amount of rotation or the arbitrary turning force from an output shaft. A steering handlebar can be configured to be coupled to the input shaft. A support bracket can be configured to be coupled to the output shaft and to support a front wheel of the vehicle. A housing can be configured to accommodate the steering unit. The steering unit can be configured to be mounted to a front end portion of a vehicle body frame of the vehicle integrally therewith by the housing.

Abstract: A materials handling vehicle is provided comprising a frame comprising an operator's compartment, wheels supported on the frame, at least one of the wheels being a steerable wheel, and a steer-by-wire system associated with the steerable wheel to effect angular movement of the steerable wheel. The vehicle further comprises a control apparatus.

Abstract: A rollover avoidance system for changing the damping characteristics of suspension dampers at each wheel of a vehicle so as to mitigate the potential for vehicle rollover. The system includes a plurality of vehicle parameter sensors for measuring vehicle parameters and providing vehicle parameter signals. The system also includes a controller for generating a damper suspension command signal for each damper using the vehicle parameter signals. The controller considers a roll control factor representing a rollover condition of the vehicle and a yaw stability control factor representing a yaw condition of the vehicle to set the damping of the dampers to mitigate the potential for vehicle rollover.

Abstract: Provided is an electric power steering control apparatus, including: a motor for generating an assist torque for supplementing a steering torque; a steering torque detector for detecting the steering torque; a vehicle speed detector for detecting a speed of the vehicle; an addition command torque receiving portion for receiving an addition command torque; a steering assist torque calculating portion for calculating a steering assist torque for supplementing the steering torque; a target assist torque calculating portion for adding the steering assist torque and the addition command torque together to calculate a target assist torque; and a motor driving portion for driving the motor based on the target assist torque, in which the steering assist torque calculating portion calculates an added value of the steering torque and the addition command torque, and multiplies the added value by a gain corresponding to the vehicular speed to calculate the steering assist torque.

Abstract: A steering angle sensor comprises a main rotor which can be rotated in a rotationally synchronous manner and which can be coupled to a steering column or to a steering wheel. The main rotor can be rotated about the rotational axis of the steering column. The steering angle sensor also comprises at least one additional rotor which can be driven by the main rotor, a first scanning unit which is used to scan the position of the rotational angle of the main rotor, and a second scanning unit which is used to scan the rotational angle of the additional rotor. The additional rotor can be rotated about the rotational axis of the steering column and can drive the additional rotor of at least one transmission element driven by the main rotor. A method for determining the absolute steering angle of a steering wheel is also disclosed.

Abstract: A method for generating a return torque signal in an electric servo steering system of a vehicle, including the steps of: determining a current steering wheel position; determining a current vehicle speed; generating a return torque signal as a function of the steering wheel position and the vehicle speed; determining a current speed of steering wheel rotation; determining a scaling factor dependent on the speed of steering wheel rotation; and multiplying the return torque signal by the scaling factor in order to obtain a modified return torque signal. Also, a servo steering system which is designed to carry out such a method.

Abstract: When the driver makes a counter-steer operation to steer back the steering wheel during the execution of an automatic oversteer suppress control by the turn behavior control device, the counter-steer of automatically decreasing the steering angle of the steered wheels and the counter-steering by the driver overlap to cause an excessive counter-steering. In order to avoid such a problem, when the driver makes a counter-steering operation while the turn behavior control device is executing the automatic decrease of the steering angle, the amount of automatic decrease of the steering angle is reduced according to the counter-steering operation by the driver.

Abstract: The rotational angle correction controller includes a second correction amount-computing part that computes a second correction amount ?2 for correcting the rotational angle ? such that the phase is shifted in the steering operation direction, and the rotational angle correction controller performs the rotational angle correction by adding the computed second correction amount ?2 to the rotational angle ?. Further, the rotational angle correction controller includes a stuck steering wheel determining part that detects the significant reduction in the follow-up performance of the motor with respect to the steering operation that occurs due to the existence of the deceleration section caused by execution of the above-described electric current restriction, that is, the occurrence of the stuck steering wheel. When the occurrence of the stuck steering wheel is detected, the second correction amount-computing part changes the second correction amount ?2 to a value (?2?) larger than the normal value.

Abstract: The invention relates to a steering system (10) for a motor vehicle.

Abstract: The present invention provides a controller of an electric power steering device which does not apply an uncomfortable feeling to a operation of steering wheel while securing a fault determination confirming period enough long to prevent an erroneous detection of a torque sensor fault, and can secure a safety operation of steering wheel, even in the case that an output value of a torque sensor detecting a steering torque of a steering wheel becomes abnormal.

Abstract: A steering system for a vehicle is disclosed. The steering system includes variable gear ratio steering apparatus, a first ECU for controlling the apparatus, an electric power steering apparatus, a second ECU for controlling the apparatus, The steering system further includes a steering wheel angle sensor and a steering wheel angle ECU, which are integrated. The steering wheel angle sensor detects a steering wheel angle of a steering wheel. The ECU calculates an estimation value of the steering wheel angle of the steering wheel and compare between the estimation value and the detected value of the steering wheel angle. Thereby, the ECU performs a process of determining detection accuracy of the steering wheel angle sensor.

Abstract: A steering apparatus for a vehicle, includes: an operation unit; an input operation magnitude measuring unit; a turning actuator turning steerable wheels; a reaction force actuator; a turning actuator control unit; a reaction force actuator control unit; a planetary gear unit disposed between the operation unit and the turning actuator; a locking element fixing and releasing a component of the planetary gear unit; a locking element operation unit; a locking state detection unit; and a control unit executing at least one of the control operations for increasing magnitude of a control parameter for the turning actuator and for increasing magnitude of a control parameter for the reaction force actuator if it is determined by the locking state detection unit that the locking element is placed in a locked state even though the locking element operation unit is operated so as to place the locking element in the locked state from an unlocked state.

Abstract: The method consists in: determining in which actually sector the booster motor is located, a sector of the booster motor being defied by two successive poles; determining a relative angle position of the steering wheel in relation to the booster motor; identifying a sector, known as neutral, in which the booster motor is located when the rotation speeds of the rear wheels, i.e. right and left of the vehicle, are equal; determining an angle offset of the steering wheel corresponding to a neutral angle position of the steering wheel; determining an absolute angle position of the steering wheel which is equal to the difference between the relative angle position of the steering wheel and the offset angle thereof.

Abstract: A steering system for a motor vehicle, including a steering gear and at least one tie rod, is characterized in that an actuator is provided, which can move an end section of the tie rod transversely to the direction in which the end section can be adjusted by the steering gear. A method of controlling a vehicle, in which steerable wheels of a vehicle are acted upon, is characterized in that a correction steering angle is superimposed on a steering angle of the steerable wheels which is given by a steering gear, which correction steering angle is brought about by an actuator which acts on one of the steerable wheels.

Abstract: An electric power steering system includes a steering wheel, an electric assist motor operatively coupled to the steering wheel, and an electronic controller operatively coupled to the motor for receiving a first signal representative of torque applied to the steering wheel, and a second signal representative of angular velocity of the motor. The electronic controller produces an active damping motor command signal according to a function of the first and second signals. The active damping motor command signal is scaled by a first factor if the first and second signals are both positive, or if the first and second signals are both negative, to provide a scaled motor command signal. The active damping motor command signal is scaled by a second factor if the first signal is positive and the second signal is negative, or if the first signal is negative and the second signal is positive, to provide the scaled motor command signal. The scaled motor command signal is applied to the motor.

Abstract: A vehicle steering apparatus that can prevent a large returning torque from acting when a steering wheel is turned. Through processing of an assist control program, rotational torque (assist torque) of an electric motor is calculated by adding returning torque g*Trto to turning torque Tc (in actuality, subtracting the returning torque g*Trto from the turning torque Tc). The electric motor is driven and controlled in accordance with the calculated assist torque. When the steering torque is large, the calculated returning torque gain g decreases, and therefore, the returning torque g*Trto decreases or becomes zero. With this control, the greater the force (torque) required to operate the steering wheel, the smaller the influence of the returning torque, and steering feel at the time of turning the steering wheel is improved.

Abstract: A method of steering a vehicle with a superimposed steering system, wherein a steering angle input by the driver and an additional angle (additional steering angle) is determined and wherein the additional steering angle can override the input steering angle according to further quantities, in particular diving-dynamics quantities, by means of an electric motor, is characterized in that the method includes a steering angle control with a subordinated current or torque control of the electric motor.

Abstract: A vehicle steering apparatus is comprised of an assist motor, a steering torque sensor, a steering angle sensor, and a controller. The controller has a torque producing section for estimating a virtual steering model input torque from a torque sensor detection value and a steering angle detection value, a virtual steering model of representing a desired steering characteristic which receives the virtual steering model input torque and outputs a target steering angle of a steering column shaft, and a steering angle servo for controlling an output of the assist motor so that the steering angle detection angle follows the target steering angle.

Abstract: A steering assist system for a motorcycle includes an actuator configured to provide a steering torque to steering of a motorcycle. A target-torque calculation unit is configured to obtain a target-torque for the steering, on a basis of a state of the motorcycle. A torque detecting unit is configured to detect a steering torque. A torque control unit is configured to drive an actuator on a basis of a deviation between the target torque obtained from the target-torque calculation unit and the steering torque obtained from the torque detecting unit.

Abstract: An electric power steering apparatus is provided for suppressing the effect on the steering wheel of external interference inputted from the tie rod. The apparatus includes first and second output units for outputting first and second control amounts in accordance with the outputted torque signal, except in a dead zone thereof, respectively. The apparatus also includes gain data output units for, when the torque signal, a steering angular velocity, and a vehicle speed are within predetermined ranges, outputting gain data respectively. Steering operation is assisted by an electric motor driven on the basis of the first and second control amounts and the gain data, which afford a control signal to the motor.

Abstract: A steering control system includes a steering wheel and a steering shaft with upper and lower shaft portions. Steering shaft torque of the lower shaft portion corresponds to torque transmitted to the upper shaft portion, and steering shaft torque steers vehicle wheels. A steering torque detector is included for detecting steering torque. An assist force generating device generates assist forces according to a control signal to thereby generate torque in the lower shaft portion. A controller is included for outputting the control signal based upon the steering torque. A vehicle speed detector detects speed of the vehicle, and an environment information detector detects environment information. A basic assist amount is set according to the vehicle speed and the steering torque, and a torque correction amount is determined based upon the environment information. Additionally, the assist force is determined based upon the basic assist amount and the torque correction amount.

Abstract: A plurality of magnetic pole bodies, provided on a stator of a steering motor, are divided into two electrically independent groups. Each group includes i) six magnetic pole bodies that are arranged in succession and ii) a corresponding number of magnetic pole bodies arranged opposing those six magnetic pole bodies. The two groups vibrate only slightly when operating normally. However, if one of the groups fails, vibration of the stator from elastic deformation in an undulating manner in the circumferential direction will increase, thereby alerting the driver of an abnormality in the steering motor. This increases the likelihood of measures being taken promptly to fix the abnormality in the steering motor, thus improving fail-safe performance.

Abstract: There is provided a power steering apparatus comprising a torque sensor detecting a steering torque capable of discriminating a normal input and an inverse input without a torsion bar. An intermediate gear engaging with rack teeth provided in an outer surface of a rack shaft and a pinion provided in a lower portion of a pinion shaft is interposed between both the rack tooth and the pinion. A force applied to the pinion shaft is detected by a first force sensor, a force applied to a support shaft of the intermediate gear is detected by a second force sensor, and a torque detection value capable of discriminating the normal input and inverse input is calculated by a torque calculating unit to which outputs of both the sensors are given.

Abstract: An electric power steering system includes an assisting electric motor for assisting steering force according to a vehicle speed and a steering torque, a power supply source and an electric power steering controlling portion for supplying power to the assisting electric motor from the power supply source for controlling the assisting electric motor. The electric power steering controlling portion completely stops the controlling of the assisting electric motor being controlled and stops operating when the power supply source is in a first abnormal state and temporarily stops the controlling of the assisting electric motor being controlled until the power supply source returns to a normal state from a second abnormal state when the power supply source is in the second abnormal state.

Abstract: When an electrification failure occurs in any of the phase of a motor, a control device of an electric power steering device executes current control for generating, in each of two electrification phases other than a phase with the electrification failure, a phase current that changes in the form of a secant curve or a cosecant curve based on an asymptotic line, which is a predetermined rotational angle corresponding to the phase with the electrification failure, to thereby continuously output a motor control signal. The control device of the electric power steering device executes current restriction for restricting the phase current within a predetermined range. The control device of the electric power steering device further executes control for accelerating rotation of the motor during two phase drive, in order to prevent the occurrence of a stuck steering wheel during low-speed steering, which is caused as a result of the execution of the current restriction.

Abstract: A steering system includes a steering wheel, a steering angle sensor detecting a steering angle, a steering motor steering road-wheels, a reaction motor imparting a reaction force to the steering wheel, an ECU driving the steering motor with respect to a detected steering angle and a temperature detecting unit detecting temperatures of the steering motor, the reaction motor or a constituent member involved in the temperatures of the motors. When the temperature detected is larger than a predetermined value, the ECU performs such that a ratio of the rotating angle to the steering angle is made smaller than one that is to result when the temperature is equal to or smaller than the predetermined value, or a reaction force that is to be imparted to the steering wheel is made larger.

Abstract: An electric power steering device which has, on the outer surface of its gear box, the circuit modules of a control device such as a power module, a frame module, and a control module, and which is easily mountable on a vehicle and less affected by heating. The upper half of the gear box (11) is formed in a rectangular parallelepiped box (11b) in which a reduction gear mechanism is assembled. The first flat face (11b1) of the gear box (11) on the outside of the axis of the center shaft of an electric motor (12) as viewed from a worm gear meshing point is formed as a mounting face for the power module (PM), and the second flat face (11b2) of the gear box crossing the first flat face is formed as a mounting face for circuit parts forming the frame module (FM) and the control module (CM).

Abstract: A electric power steering apparatus having a steering torque detecting unit for detecting a steering torque transmitted to the steering system; an electric motor for generating a steering assist force to give to the steering system; a motor control unit for controlling the electric motor based on at least the steering torque. The apparatus comprises a motor stop condition detecting unit for detecting a condition to stop the electric motor while the electric motor is under control by the motor control unit; and an electromagnetic brake control unit over the electric motor in order to suppress a kick-back based on at least either one of a steering condition of the steering system and a running condition of the vehicle when a detection result by the motor stop condition detecting unit shows that a condition occurs to stop the electric motor.

Abstract: An operation torque estimating portion estimates an operation torque Th of a driver based on an input angle ?h and an input torque T output from a torque sensor. A non-holding state detecting portion determines whether the driver is holding a steering wheel by comparing an absolute value of the operation torque Th and a predetermined value ?1. An equilibrium detecting portion determines whether an equilibrium point is reached by comparing the absolute value of the input torque T with a predetermined value ?2. When it is determined that the driver is not holding the steering wheel and the equilibrium point is reached, a switching portion switches to such a position that causes a target steering adjusting portion to multiply a target output angle ? pm by a predetermined gain G according to the input torque T so that the target steering angle is made smaller.

Abstract: A steering system with reduced coupling between a position overlay unit and a torque overlay unit may include a remote valve assembly for controlling a hydraulic assist force or an electric motor for providing torque overlay and electric assist to a rack of a rack and pinion steering system. In one embodiment, the position overlay unit may provide the assist force and the torque overlay unit may provide a motor command signal to the motor of a differential positioned on a steering shaft. In another embodiment, the position overlay unit may provide the motor command signal and the torque overlay unit may provide the assist force. In either embodiment, the position overlay unit may include variable ratio gain that uses a position signal to output a variable ratio command.

Abstract: An electric power steering system which includes a torque detector for detecting a steering torque applied to a steering member and a steering assist brushless DC motor, whereby a plurality of phase currents are caused to flow to the brushless DC motor based on the steering torque detected by the torque detector so as to give steering assistance. A current detector for detecting each of the plurality of phase currents, an adder for adding up respective values of the currents detected by the current detectors and a determination device for determining whether or not a result of an addition by the adder falls outside a predetermined range are provided, whereby it is designed to determined as abnormal when the determination device determines that the result of the addition falls outside the predetermined range.

Abstract: A steering system for a vehicle, includes a control operated by a driver of the vehicle; a measuring device for measuring a quantity of operation of the control by the driver; a steering section including a steering actuator for steering wheels which are mechanically independent of the control; a section for setting a target steering angle in accordance with the quantity of operation measured by the measuring device; a reaction actuator for applying a steering reactive force to the control; a section for setting a virtual steering angle based on a virtual model which represents predetermined dynamic characteristics of the steering section; and a reaction control section for setting a target reactive force in accordance with a difference between the target steering angle and the virtual steering angle, and controlling the reaction actuator based on the target reactive force.

Abstract: Disclosed is an electric power steering system including a housing; a steering shaft positioned in the housing; a worm wheel mounted on the steering shaft; a worm shaft; a worm gear formed on the worm shaft so as to mesh with the worm wheel; a motor for driving the worm shaft; a first worm shaft bearing positioned on an end of the worm shaft; and an elastic member for applying a load to the first worm shaft bearing in a diametric direction, the elastic member being formed by double-folding a leaf spring in an approximately U-shaped configuration, both ends of the elastic member being supported by the housing, a central portion of the elastic member abutting an outer peripheral surface of the first worm shaft bearing.