Abstract: An occupant restraint device controller, including an electronic circuit substrate incorporating therein a control circuit that determines whether or not a vehicle has collided based on a detection output of a sensor detecting acceleration/deceleration of the vehicle and outputs a control signal for activating an occupant restraint tool. The electronic circuit substrate is accommodated inside a resin case provided with a structure for leading out a ground electrode from the inside to the outside of the resin case. The structure for leading out a ground electrode is configured such that a fixing leg, for fixing the electronic circuit substrate, is provided inside the case.

Abstract: When an inverter or a coil set of one system fails in a motor drive apparatus having two power supply systems, a power supply relay of a failing system is turned off. In this case, while a travel speed detection value is less than a predetermined threshold value, current supply to a motor by the other system operating normally is stopped to thereby stop driving of the motor and generate no steering assist torque. Thus, a driver will be caused to surely notice occurrence of failure.

Abstract: A vehicle steering control apparatus includes an actuator to vary a steering gear ratio of a vehicle wheel steer angle of a steerable wheel to a steering wheel angle. A controller controls the actuator to produce an actuator torque in a steering direction at a start of a driver's steering operation.

Abstract: Disclosed is a reducer of an electric power steering apparatus. The disclosed reducer includes: a worm shaft bearing coupled with an end of the worm shaft's motor shaft coupling portion in such a manner that a ball coupled between an inner wheel and an outer wheel supports rotation of the worm shaft; and a first damper and a second damper which are tightly fitted in one side and the other side of the worm shaft bearing, respectively, while being insertedly-coupled with the worm shaft, so as to support the worm shaft and absorb a rattle noise transferred via the worm shaft, wherein each of the first damper and the second damper is provided with supporting plates at both sides thereof, and between the supporting plates, a damper made of an elastic material is coupled and formed.

Abstract: A circuit board unit of an ECU has an upper surface on which semiconductor elements are installed, a lower surface that is on the opposite side of the circuit board unit from the upper surface, and a cutout portion that is formed below the upper surface. A power module includes a conductive protruding piece and an electrically insulating main portion that holds the protruding piece. The conductive protruding piece is inserted in the cutout portion to support the circuit board unit, and is electrically connected to the semiconductor elements.

Abstract: A variable transmission ratio mechanism is provided on an intermediate portion of a steering shaft, and is able to change a transmission ratio between a shaft on the steering wheel side and a shaft on the steered wheel side by transmitting the sum of rotation of the first shaft and rotation of a rotary shaft of a motor to the second shaft. The variable transmission ratio mechanism is provided with a lock mechanism that restricts the operation of the variable transmission ratio mechanism. When the fact that a rate of change in torque that acts on the steering shaft exceeds a predetermined rate is detected, a period of time until the torque that acts on the steering shaft reaches a torque determination value is estimated. On the condition that the estimated time is shorter than or equal to a predetermined period of time, the lock mechanism is activated.

Abstract: A method for operating an active steering system of a vehicle, in which a ratio between a wheel steer angle and a steering wheel angle specified by the driver can be modified by superimposition of a superimposition angle. The method comprises detecting an offset between a requested motor angle and an actual motor angle, and reducing the offset between the requested motor angle and the actual motor angle using a reduction rate that is selected as a function of at least one input variable specified by the driver.

Abstract: A vehicle steering control device includes an electric power steering unit, a steering ratio varying unit which drives an output member relative to an input member driven by steering operation of a driver to vary a steering ratio, and a control unit which controls the steering ratio varying unit. The control unit decreases in magnitude the relative drive velocity of the output member driven by the steering ratio varying unit relative to the input member when the magnitude of a difference between the maximum value of the steering drive velocity range of said steerable wheels which allows said power steering unit to generate a required steering assisting power and an actual steering drive velocity of said steerable wheels is small in contrast to the large difference.

Abstract: A steering drive for a motor vehicle comprising a steering wheel, a steering column, on which the steering wheel is disposed, a connecting rod, which interacts with the steering column to deflect the wheels of the motor vehicle, an electric motor, which is provided for boosting the steering thrust, as well as a belt drive, the electric motor interacting with the connecting rod via the belt drive. Said electric motor comprises a stator having twelve stator teeth as well as a rotor having ten rotor poles, the rotor poles being spaced apart from each other by an air gap and embodied as sinus poles.

Abstract: An assist control portion, upon detecting source power supply abnormality of a main electric power source, switches the characteristic of an assist map in which the steering torque and the target current are related to each other from an original assist characteristic to an abnormality-time assist characteristic. Therefore, the steering handle operation suddenly becomes heavy, thereby causing the driver to be aware of the abnormality. After that, the abnormality-time assist characteristic is altered so that the assist force relative to the steering torque further decline in accordance with declines in the actual amount of charge of the subsidiary electric power source declines. Therefore, the steering handle operation gradually becomes heavier, thereby causing the driver to anticipate that the abnormality is further progressing.

Abstract: A power transducer failure detection device detects a failure on a power transducer, making a power transducer control device stop driving the power transducer. A first switching control device turns off a first power supply relay of a power supply source switching device and turns on a second power supply relay of the power supply source switching device. While the power transducer stops driving, a motor may rotate due to an external force to generate a regenerative voltage. The regenerative voltage is then regenerated in a battery through a route from the power transducer via the second power supply relay being turned on and a parasitic diode of the first power supply relay. This can protect elements such as switching elements and a smoothing capacitor of the power transducer against a regenerative voltage and prevent the elements from being destroyed or reducing the useful life due to overvoltage.

Abstract: A system and method for controlling a vehicle steering system, comprising receiving at least one signal corresponding to one or more of a lateral acceleration, a longitudinal acceleration, a vertical acceleration, a suspension travel, and a vehicle speed, calculating or determining an optimum steering rack travel from the at least one signal, and limiting travel of a steering rack of the vehicle based on the optimum steering rack travel.

Abstract: A control method for an automotive vehicle steering system including an electric motor providing a steering force on a steering mechanism. The method comprises providing at least three steering system MAPs which control an electric current supplied to the electric motor. Wherein if a new MAP is selected when at least two prior selected MAPs are blending, the MAP comprising the greatest component of a blend at the time the new MAP is selected is decreased at a faster rate than the MAP comprising the lesser component.

Abstract: An angular velocity estimate (?e) used in motor control of an electric power steering is obtained as follows. In a first state period during which the motor substantially stops its rotation, a resistance calculation unit calculates a motor resistance value (Rc) on the basis of a detected value (Vm) of motor voltage and a detected value (Im) of motor current. An average calculation unit obtains an average value (Rav) of the calculated resistance values (Rc) in a retained period. A current-resistance characteristic that associates motor current with motor resistance is held in a characteristic holding unit, and a characteristic updating unit updates the current-resistance characteristic on the basis of the average value (Rav). An estimate calculation unit calculates the angular velocity estimate (?e) on the basis of the detected value (Vm) of motor voltage, the detected value (Im) of motor current and a motor resistance value (Rm) obtained from the current-resistance characteristic.

Abstract: A method for controlling the response of an electric steering system by implementing damping for over-speed conditions is disclosed. The method includes the step of determining the velocity of an electric motor within the electric steering system, and determining a voltage limit value, wherein the voltage limit value is calculated as a function of the velocity of the electric motor. The method further includes the step of associating the voltage limit value with a motor voltage command in order to produce a limited voltage command, and applying the limited voltage command to the motor in order to provide a braking torque to the motor.

Abstract: A system and a method for determining an absolute rotational position of the vehicle handwheel are provided. In one exemplary embodiment, a method includes monitoring an amount of torque applied to the vehicle handwheel. The method further includes monitoring a rotational speed of the vehicle handwheel. The method further includes setting an absolute position value indicating the absolute position of the vehicle handwheel equal to a predetermined steering travel limit of the vehicle handwheel when both the amount of torque applied to the vehicle handwheel is greater than or equal to a threshold torque level, and the rotational speed of the vehicle handwheel is less than or equal to a threshold rotational speed. The method further includes storing the absolute rotational position value in a memory device.

Abstract: An electric power steering apparatus including a motor includes: a steering torque sensor; a speed sensor; an auxiliary steering force setting unit configured to output a signal representing a linear change of a gradual increase or decrease; a map setter configured to receive a signal output from the auxiliary steering force setting unit and to set an auxiliary steering force map where a maximum steering torque, a maximum target motor current, or a ratio of a target motor current to a steering torque at a specific speed gradually increases or decreases; a current signal supply configured to output the steering torque signal and a target motor current signal corresponding to the speed signal according to the auxiliary steering force map; and a motor driving unit configured to supply a current corresponding to the target motor current signal to the motor.

Abstract: An electrical angle estimation section calculates an estimative electrical angle on the basis of an inductive voltage generated in a motor, and obtains an estimative electrical angle by correcting the estimative electrical angle by an electrical angle correction amount. On the basis of a detection value which represents the difference in electrical angle between the q-axis and the ?-axis calculated by an electrical-angle-error detection section, an electrical-angle-correction-amount computation section calculates an electrical angle correction amount such that the electrical angle of the ?-axis falls within a prescribed angular range, which lags behind the q-axis in terms of electrical angle. Thus, when sensorless control is performed, a phenomenon in which the motor loses synchronism can be restrained.

Abstract: An electric power steering apparatus is configured in such a way as to include a first filtering unit that applies filtering processing to the detected steering torque signal and outputs the processed torque signal; a control unit that generates and outputs a motor drive signal, based on a steering torque signal outputted from a first filtering unit; a second filtering unit that applies filtering processing to the detected steering torque signal and outputs the processed torque signal; and an interlock unit that generates and outputs a motor drive inhibition signal, based on the steering torque signal outputted from the second filtering unit. The second filtering unit performs filtering processing in such a way as to output a steering torque signal the same as or similar to the steering torque signal that is outputted from the first filtering unit at least when a vehicle is in a predetermined driving condition.

Abstract: A steering system includes: an operation mechanism that includes an operation member; and a steered mechanism that is not mechanically coupled to the operation mechanism and that steers a wheel on the basis of a steering operation of the operation member. The operation mechanism includes a steering angle sensor that detects a steering angle of the operation member and a steering direction detection unit that detects a steering direction of the operation member. The steering direction detection unit includes a threaded shaft that is rotatable in the steering direction of the operation member, a nut that is screwed to the threaded shaft, a nut guide that causes the nut to move in an axial direction of the threaded shaft in accordance with rotation of the threaded shaft, and a force detection sensor that detects a force that the nut guide receives from the nut.

Abstract: A steering system includes: an operation mechanism that includes an operation member used to perform a steering operation; and a steered mechanism that is not mechanically coupled to the operation mechanism, and that steers a wheel based on the steering operation of the operation member. The operation mechanism includes a steering angle sensor that detects a steering angle of the operation member, and steering direction detection unit that detects only a steering direction of the operation member.

Abstract: In a steering system, an operation mechanism that includes an operation member includes: a steering angle sensor that detects a steering angle of the operation member; and a steering direction detection unit that detects a steering direction of the operation member. The steering direction detection unit includes: a threaded shaft that is rotatable in the steering direction of the operation member; a nut that is screwed to the threaded shaft; a nut guide that causes the nut to move in accordance with rotation of the threaded shaft; a stopper that prevents movement of the nut beyond a predetermined position; a proximity detection sensor that detects a fact that the nut is in proximity to the stopper; and a variable axial length mechanism that reduces a clearance between the nut and the stopper in response to occurrence of a malfunction in the steering angle sensor.

Abstract: A driving dynamics control system for vehicles. The control system including at least one driving dynamics controller that is fed setpoint specifications and driving state variables as input data. The control system also includes a plurality of actuators that can be controlled and/or regulated to modify the dynamics of the vehicle, such as steering, adjustable independently of the driver, on a front and/or rear axle of the vehicle, a chassis adjustable independently of the driver, a brake adjustable independently of the driver, and a drive train adjustable independently of the driver. The driving dynamics controller determines a central control specification from the setpoint specifications and the driving state variables and sends it to a distribution algorithm that distributes the control specification into manipulated variables for driving the actuators.

Abstract: An electric power steering apparatus drives a motor to generate a steering assist force according to a steering torque and includes an output circuit for supplying the motor with electric power from at least one of a battery and an auxiliary power supply. The electric power steering apparatus has a control circuit which at or after detection of a breakdown of the battery, determines a length of time to the end of steering assist (decreasing time t1) based on the amount of energy stored in the auxiliary power supplies and which takes the determined length of time to perform output decreasing control to gradually decrease the upper limit of power supplied for the steering assist to practically zero according to a constant gradient. Thus is provided an electric power steering apparatus which is adapted to prevent a sudden fall of the steering assist force in the event of a battery breakdown while effectively utilizing the available stored energy.

Abstract: In an electric power steering apparatus of the invention, a control circuit determines a command value of drive voltage supplied to a motor drive circuit based on an actual current through a motor and a target current. When the command value exceeds the previous value having a lower limit equivalent to a limit value representing the limit of the power supply from a battery, the control circuit controls the amount of discharge from the auxiliary power supply according to a difference between the command value and the previous value by increasing or decreasing a duty of switching devices. Thus, the power steering apparatus can save the energy of the auxiliary power supply for efficiently using the auxiliary power supply.

Abstract: Disclosed are a pinion sensor assembly and an electric power steering apparatus having the same. According to the present invention, it is possible to substantially reduce the number of constitutional elements to be assembled when assembling a torque sensor and neighboring elements, to reduce an error in change of torque caused by accumulation of assembling errors of the constitutional elements, thereby preventing a malfunction, and to enhance assemblability.

Abstract: A magnetostrictive torque sensor includes a magnetostrictive portion formed on a rotational shaft, a bobbin surrounding an outer circumference of the magnetostrictive portion, and a coil wound on the bobbin for detecting a change in magnetic property of the magnetostrictive portion. The bobbin fits over the magnetostrictive portion in contact with the magnetostrictive portion in such a manner as to allow rotation of the magnetostrictive portion relative to the bobbin. The magnetostrictive torque sensor is carried on an electrically assisted bicycle or an electric power steering apparatus of a vehicle.

Abstract: A control method for an electric power steering system is provided. The control method includes evaluating wheel disturbance based on a wheel velocity. A wheel disturbance cancel amount is determined based on the wheel velocity. An assist command is generated to the power steering system based on the wheel disturbance cancel amount.

Abstract: An electric power steering system of a vehicle includes a controller for controlling an electric motor connected to a steering column or other steering mechanism. The velocity of the motor must be determined to maintain the proper current to the motor. A method of estimating the velocity includes obtaining a first and second velocity signals from one or more sensors monitoring the motor. The first and second signals have different characteristics, e.g., the first signal may have a higher resolution than the second signal. An acceleration (or deceleration) of the velocity of the electric motor is computed based on the different representations of the velocity supplied by the different signals. An estimate of the velocity of the motor is then determined based on the acceleration/deceleration and the different representations of the velocity. The electric current provided to the electric motor is then adjusted based on the estimated velocity to meet the desired motor output (i.e., motor torque and velocity).

Abstract: The invention concerns a method which includes: filtering the torque signal using a low-pass filter of the first order at a variable cut-off frequency which takes on, respectively, a minimum value or a maximum value depending on whether the amplitude of the torque signal is, respectively, lower or higher than a predetermined threshold; then in producing a signal indicating, respectively, a steering wheel release or a steering wheel grip depending on whether the amplitude of the filtered torque signal is, respectively, lower or higher than a predetermined threshold.

Abstract: A torque detection device includes: a torsion bar that couples a first shaft to a second shaft such that the first shaft and the second shaft are rotatable relative to each other; an annular magnet that is fixed to the first shaft; a pair of magnetic yokes that are fixed to the second shaft and that are arranged to face the magnet; and Hall ICs. Each of the magnetic yokes has a plurality of lugs arranged at equal intervals in a circumferential direction, and each lug becomes narrower toward its distal end, and has a curved profile with rounded corners when viewed from a radial direction of the corresponding magnetic yoke.

Abstract: An electric power assisted steering system comprises a torque sensor, a motor connected to a part of the steering system to provide motor torque to the steering system and a motor controller which is adapted to receive an output signal from the torque sensor and to generate a motor torque demand signal indicative of the torque to be applied by the motor to the steering system. The motor torque demand signal comprises a driver demand component dependent upon the torque applied by the driver; and a diagnostic component independent of the torque applied by the driver and which varies in value over time in a predetermined manner. The system further comprises a monitor that correlates the diagnostic component with the output signal and generates a signal indicating that the output signal is faulty if the correlation falls outside of a predefined range.

Abstract: A motor drive apparatus includes a control circuit, which determines that a wire connecting a battery to a first power supply relay and a second power supply relay is broken, and not failure of the power supply relays, if power is not supplied to a motor from the power supply relays when the power supply relays are controlled to turn on. The location of failure can thus be specified accurately. It is only necessary in this case to replace the wire. The motor drive apparatus need not be disassembled or investigated in detail. Man-power for specifying the failure location can be reduced.

Abstract: An inverter energy consumption calculating portion estimates the actual power consumption of a steering operation assist motor after an engine is placed in an idle-stop state, and a command value of current to be supplied to the steering operation assist motor is limited such that the command value is smaller as the energy consumption is larger. The inverter energy consumption calculating portion calculates the energy consumption of an inverter drive circuit by integrating an amount of electric power consumed by the drive circuit.

Abstract: An adjusting apparatus for an electric power steering device includes a steering mechanism converting an input torque into a steering force and transmitting the steering force to wheels, a torque sensor outputting a torque detection signal according to an input torque, an electric motor applying a steering assist torque according to a torque detection signal output from the sensor, a sensor circuit changing output characteristics of the sensor, an actuator applying an input torque to the steering mechanism, a steering force meter actuating the motor via the sensor according to an input torque and measuring a steering force output by the steering mechanism, and a sensor output adjuster adjusting the output characteristic of the sensor circuit to approximate a steering force measured by the meter to an ideal value set in advance according to a deviation amount calculated based on a difference between the steering force and the ideal value.

Abstract: A torque ripple suppression control device for a permanent magnet motor includes a current command conversion unit that outputs a current command value, a position detector that detects a rotational position of the permanent magnet motor, a current detection unit that detects a current at the permanent magnet motor, an induced voltage coefficient setting unit that outputs an information signal related to an induced voltage coefficient for an induced voltage at the permanent magnet motor, a torque ripple suppression operation unit that outputs a current correction command value for the permanent magnet motor, a current control operation unit that outputs a voltage command value based upon addition results obtained by adding together the current command value and the current correction command value and the current detection value, and a power converter that outputs a voltage with which the permanent magnet motor is to be driven.

Abstract: An electric power steering apparatus includes: a detector that detects a value corresponding to a steering torque of a steering wheel; a correcting unit that corrects a detection value detected by the detector by taking into account a hysteresis between an actual steering torque and the detection value detected by the detector; and a target current calculating unit that calculates a target current which is supplied to an electric motor on the basis of a corrected detection value corrected by the correcting unit. The correcting unit makes a correction by using a correction value corresponding to the detection value detected by the detector so as to make the hysteresis small in a case where the steering torque is small and large in a case where the steering torque is large.

Abstract: A recreational utility vehicle has a frame, four wheels, a pair of seats mounted laterally beside each other, a cage, a steering assembly, an engine, a front differential, a rear differential, an actuator selectively operatively connecting the engine to the front differential, and a vehicle drive mode switch for selecting between a first and second drive mode. When the first drive mode is selected, the actuator operatively connects the engine to the front differential, and when the second drive mode, the actuator operatively disconnects the engine from the front differential. An electric motor is operatively connected to the steering assembly. A steering control unit is electrically connected to the electric motor, determines an output torque to be applied by the electric motor based at least in part on a speed of the vehicle, and controls the electric motor to apply the output torque to the steering assembly.

Abstract: A vehicle control device calculates an operation amount and a motion state amount for varying an operation amount necessary for a real vehicle's operation based on a dynamic vehicle model modeling the motion state of a vehicle running in accordance with running targets such as a target path and a speed pattern and determines whether the calculated operation amount and the motion state amount satisfy prescribed running requirements. The operation amount and the motion state amount determined to satisfy the running requirements are a feed-forward (FF) operation amount and a target state amount in a state feedback (FB) control, respectively.

Abstract: A rotating electrical machine control device includes a target current value calculation section, a PWM signal generation section, a voltage application section, and a control section. The target current value calculation section calculates target current values of electric currents supplied to windings of a rotating electrical machine. The PWM signal generation section generates PWM signals for the respective windings based on the target current values. The voltage application section applies voltages to the respective windings based on the PWM signals. When the control section stops driving of the rotating electrical machine, the PWM signal generation section generates the PWM signals in which a timing of a pulse change in the PWM signal of at least one phase is different from timings of pulse changes in the PWM signals of the other phases.

Abstract: A control for a steering support system for a two-wheeled vehicle is provided. The steering support system has an actuator with the aid of which a steering torque is applied to the two-wheeled vehicle. The actuator is, for example, an electric motor which cooperates with a steering tube. The control triggers the actuator in a targeted manner to effect a desired steering torque. Furthermore, various sensors are provided for detecting vehicle dynamics parameters, such as a steering angle, a steering torque, accelerations acting on the two-wheeled vehicle, or speeds of wheels of the two-wheeled vehicle. Based on the parameters detected by the sensors, the actuator may be triggered to effect a steering torque.

Abstract: An electric power steering system has an electric motor that is housed in a motor housing having a cylindrical portion and provides a steering assist force to a steering shaft; a control unit that controls the electric motor and has an ECU housing located on an opposite side to an output shaft of the electric motor in an axial direction of the motor housing; a power conversion circuit housed in the ECU housing and having a semiconductor switch for controlling the electric motor; and a control circuit housed in the ECU housing and controlling the semiconductor switch. The electric power steering system also has a conductive member that electrically connects an output terminal of the semiconductor switch and an input terminal of the electric motor. Part of a metal board of the conductive member is contiguous to an inner surface of the motor housing or of the ECU housing.

Abstract: A power on-demand steering angle sensor coupled to a steering wheel and a controller comprising a switch, coupled to the sensor and the controller. The switch is activated upon motion of the steering wheel or steering shaft. The switch, when closed, connects a power supply, such as a vehicle battery, to the sensor and the controller so that a new steering angle may be sensed and stored. After a predetermined period of time, the controller sends a signal to open the switch and disconnect the power supply.

Abstract: The present invention relates to a method for controlling driving stability of a vehicle wherein a number of input variables are used to control the driving speed of the vehicle to a limit speed. In order to prevent unstable driving conditions in a pre-controlled manner, a model-based stable limit speed of the vehicle is determined on the basis of measured variables that are detected by means of detection devices and represent the current steering angle and the current lateral acceleration, by including other quantities of the vehicle and/or the driving situation, and the driving speed is compared to the model-based stable limit speed of the vehicle, and based on the comparison result, the driving speed is adapted to the limit speed when the driving speed exceeds the limit speed.

Abstract: The invention relates to a steering device for a vehicle, comprising a steering drive (1) having an output shaft (2) for assisting a steering process, and a blocking device (3) for blocking the steering drive (1). Said blocking device (3) is directly arranged on the steering drive (1) and blocks the steering drive directly on the output shaft (2). The invention also relates to a method for blocking a steering device.

Abstract: Systems and methods for determining an absolute rotational position of the vehicle handwheel are provided. In one exemplary embodiment, a method includes determining a slope value based on the delta torque value associated with the vehicle steering system and the delta rotational position value associated with a vehicle handwheel. The method further includes setting an absolute position value indicating the absolute position of the vehicle handwheel equal to a predetermined steering travel limit of the vehicle handwheel when the slope value is within a predetermined slope range.

Abstract: A system and method for managing faults occurring in a power steering system in a vehicle is disclosed that has particular application for an MRHPS system to provide reliable functioning of the power steering system. The method includes detecting a fault condition in the MRHPS system and selecting a safe mode from a plurality of predetermined safe modes based on the fault condition. The plurality of predetermined safe modes include a normal operation mode, an engine speed follow mode, a manual mode, a fixed duty cycle mode and a voltage control mode. If a fault condition is detected, the method applies the safe mode to manage the fault condition.

Abstract: A torque sensor and an electric motor are supported by a steering column by which a steering shaft is rotatably supported. On a control board on which a control circuit that controls driving of an electric motor is mounted, a first terminal group and a second terminal group that are selectively connected to the torque sensor are respectively provided at a first end portion and a second end portion in a first direction parallel to a central axis of the steering shaft. A third terminal group that is connectable to the electric motor is provided at one end portion (third end portion) in a second direction perpendicular to the first direction.

Abstract: An electric power steering device for a vehicle includes an estimation mechanism estimating if there is a possibility that a backward electric current flows in a booster circuit toward a vehicle battery device, and a boosting controller stopping the boosting operation of the booster circuit to prevent a backward electric current from flowing in the booster circuit when it is estimated that there is a possibility that a backward electric current flows by the estimation mechanism. The estimation mechanism estimates that there is a possibility that a backward electric current flows in the booster circuit when the steering condition of a steering wheel is a returning condition or a steering-held condition. Otherwise, the estimation mechanism estimates if a backward electric current flows on the basis of input and output voltages of the booster circuit and information on the switching of a first boosting switching element. Thereby, overheat of the booster circuit can be prevented.

Abstract: A steering control apparatus acquires vibration torque, which is generated by vibration of a gear mechanism when a steering wheel is operated at a steering angle. By setting the acquired vibration torque as a torque difference, an EPS motor current command value is corrected based on the torque difference thereby to calculate a corrected EPS motor current command value. Rattling and vibration caused in the gear mechanism are suppressed from being transferred to the steering wheel through an input shaft so that a driver is released from uncomfortable feeling.