Abstract: A steering angle sensor 17 is provided which can minimize a detection error even when a steering shaft 6 is inclined. In an annular clearance t1 defined between the steering shaft 6 and an inner cylindrical wall of a first gear 24, there is compressed an elastic O-ring 23. Due to provision of the elastic O-ring 23, inclination of the steering shaft 6, which tends to occur during handling of a steering wheel 1, is suitably absorbed by the elastic O-ring 23, and thus, generation of detection error caused by inclination of the first gear 24, which would follow the inclination of the steering shaft 6, is suppressed or at least minimized.

Abstract: An electric power steering apparatus that is capable of obtaining a more safe and comfortable handling performance by signal processing of road information and disturbances is performed to realize easy tuning, and vibration absorption level for brake is improved by a filter and a gain unit considering a frequency characteristic and a decelerating acceleration.

Abstract: An acceleration sensor is attached to a rack housing. A FFT processing unit converts a signal output from the acceleration sensor, which is a time-domain signal, into a frequency-domain signal. An inverse input vibration component extraction unit extracts a signal, of which the frequency (f) falls within a predetermined range (fL?f?fH (fH>fL)) and of which the power density (?) falls within a predetermined range (?L????H (?H>?L)), from the frequency-domain signal obtained by the FFT processing unit. An IFFT processing unit converts the frequency-domain signal extracted by the inverse input vibration component extraction unit into a time-domain signal (estimated inverse input vibration).

Abstract: A zero point change model executes banked road correspondence control when a vehicle travels on a banked road. By this control, a target turning angle when the total torque is zero can be changed from a neutral turning angle to a lower side of an inclined road surface. Thus, a steering angle of a steering wheel according to a banked road can be realized even if the driver does not apply steering torque during traveling on a banked road. Accordingly, the driver can obtain a suitable steering feeling when traveling on a banked road while achieving the target turning angle according to the total torque.

Abstract: An end determination unit determines that a steering apparatus is in an end touching state when an angle deviation, which is a difference between an actual turning angle and a target turning angle, exceeds a threshold. This angle deviation exceeds the threshold before a large axial force is generated in a steering shaft. Accordingly, is it possible to determine that the steering apparatus is in the end touching state more quickly.

Abstract: An electric power steering apparatus includes a controller that controls, based on an assist command value, driving of a motor used to apply assist torque to a steering mechanism. The controller calculates a first assist component based on a steering torque transmitted to the steering mechanism and calculates a steered angle command value based on the steering torque. The controller executes feedback control to cause a steered angle of steerable wheels to agree with the steered angle command value, thereby calculating a second assist component. The controller calculates the assist command value based on a value obtained by adding the assist components. The controller estimates a grip factor of the wheels on a road surface on which the wheels are traveling based on the steering torque, a first assist torque determined based on the first assist component, and a second assist torque determined based on the second assist component.

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: The electric power steering apparatus is provided with: a steering torque detector that detects steering torque of a steering wheel; an electric motor that applies steering assist force to the steering wheel; a current detector that detects an actual current actually supplied to the electric motor; a target current setting unit that sets a target current to be supplied to the electric motor, on the basis of the steering torque detected by the steering torque detector; a feedback controller that performs feedback control so that the target current and the actual current coincide with each other; and a feedforward controller that performs feedforward control for increasing the actual current detected by the current detector if the target current increases, the feedforward controller including a frequency compensator that provides a smaller amount of increase in the actual current as a frequency of a variation in the target current is lower.

Abstract: A regenerative braking method for a motor vehicle, in which the regenerative braking action is applied progressively, a rate of application of the braking action being dependent on a speed of the motor vehicle.

Abstract: An electrical power-steering system for motor-vehicles includes a first pinion and a second pinion meshing with two portions of a rack member which controls the steering angle of the wheels. The two pinions are driven by respective electric motors which are in turn controlled by an electronic control unit. The two portions of the rack member are constituted by two separate elements connected to each other by a connection member interposed therebetween, such that the first and second portions of the rack member behave like a single rigid element when they are driven with identical displacements in a steering maneuver, whereas the connection member allows for a relative movement in the longitudinal direction of the first and second portions of the rack member, with a resulting lengthening or shortening of the rack member, when the first and second portions of the rack member are driven with differentiated displacements in an operative mode for adjustment of the convergence angle of the wheels.

Abstract: An electric power steering device includes: a fail-safe power relay (9a) and a motor relay (10a) for interrupting power supply to an electric-motor driving unit for driving an electric motor for applying an assist torque for steering performed by a driver; and a relay driving circuit (8a) including a switch (13a) connected in parallel to drive coils of the relays (9a and 10a) and a diode (16a). A target value of a relay-contact energizing current is lowered and the relays (9a and 10a) are gradually interrupted while an amount of current corresponding to a back surge generated when the relays are turned OFF is caused to flow back to the diode (16a) of the relay driving circuit (8a) in a normal relay-OFF operation, whereas the relays (9a and 10a) are quickly interrupted without operating the relay driving circuit (8a) in case of detection of an abnormality.

Abstract: A CPU changes a turning angle corresponding to a steering angle required for a steering device to steer a host vehicle, depending on the amount of operation for moving a steering wheel at a reference position in a tilt direction and a push-pull direction. A tilt reaction force device and a push-pull reaction force device generate a reaction force against a second operation amount for moving the steering wheel from the reference position according to the reference position of the steering wheel relative to the driver which is adjusted by a tilt/expansion mechanism. In this way, even when the reference position of the steering wheel is changed, it is possible to give an appropriate reaction force to the driver since a reaction force against, for example, an operation of pushing or pulling the steering wheel is generated according to the reference position of the steering wheel relative to the driver.

Abstract: Disclosed is a rack driven electric power steering apparatus in which balls can be introduced in a state where end caps are assembled within a ball nut, impact noise and friction noise can be reduced when the balls circulate, and a separate assembling device for injection of the balls is not required, making it possible to shorten a manufacturing and assembling process.

Abstract: Disclosed is a method for determining a toothed rack force on a steering device in a vehicle, wherein the toothed rack force (forZS) is determined as a function of a plurality of models, and wherein a component (forESM) of the toothed rack force (forZS) which relates to a driving process is generated by means of a first model, and a component of the toothed rack force (forZS) which relates to a parking process is generated by means of a second model.

Abstract: An apparatus for use in turning steerable vehicle wheels includes a power steering motor assembly connected with the steerable vehicle wheels. An engine driven pump connected with the power steering motor assembly is driven by an engine of the vehicle to supply fluid under pressure to the power steering motor assembly. A controller increases engine speed when the vehicle is motionless and a steering wheel is rotated. A method for controlling the speed of an engine to provide a predetermined steering assist to a steering apparatus includes determining if the vehicle is motionless and determining if the steering wheel is being rotated. The speed of the engine is increased if the vehicle is motionless and the steering wheel is being rotated to provide the predetermined steering assist to the steering apparatus.

Abstract: An electric power steering device includes a rack bar; a pinion shaft meshing with the rack bar; a worm wheel provided on the pinion shaft; a worm shaft meshing with the worm wheel; an electric motor provided on the worm shaft; a first housing accommodating at least a part of the rack bar and the pinion shaft and includes a first bolt boss formed with a through-hole; a second housing; and a bolt. The second housing includes a worm-wheel accommodating portion accommodating the worm wheel, and a second bolt boss provided to have a shorter distance to the first housing than that of the worm-wheel accommodating portion, and formed with a female-threaded portion. The second bolt boss is opposed to the first bolt boss to cause the female-threaded portion to be continuous with the through-hole of the first bolt boss. The bolt fastens the first housing to the second housing.

Abstract: An object of the present invention is to provide a steering system which does not cause the driver to feel the steering reactive force shock when the operation of the steering wheel is stopped, and which enables the driver to operate the steering wheel comfortably. In order to achieve the above object, there is provided a steering system in which a transfer ratio of a steering angle of a steering wheel to a turning angle of a turning wheel is changed by a variable transfer ratio mechanism, and an auxiliary power is generated during steering by an electric power steering, including: a transfer ratio variable motor for changing the transfer ratio, in which a steering angular velocity of the steering wheel is calculated, and when an absolute value of the steering angular velocity becomes equal to or less than a predetermined value, a current value flowing through the transfer ratio variable motor is set to zero.

Abstract: A vehicle steering device has an electric power abnormality detection portion that detects abnormality of the source power supply capability of an electric power source device, a vehicle speed detection portion that detects the vehicle speed, and a motor control portion that controls the driving of the electric motor on the basis of the steering torque detected by the steering torque detection portion. The motor control portion enhances the output restriction of the electric motor if the vehicle speed detected by the vehicle speed detection portion declines while the abnormality of the source power supply capability of the electric power source device is detected by the electric power abnormality detection portion.

Abstract: A motor control circuit includes a power relay, a converter division, a smoothing condenser, a control circuit and a motor drive circuit, and is connected to a battery as high voltage power and to an electrical motor. The battery is connected with a driving battery having the high voltage such as 288V etc. A step down circuit reduces the high voltage to a low voltage such as 36V etc., charges a low voltage charge device and supplies drive power to the motor drive circuit. When the vehicle collision is occurred, the control circuit detects the collision by a value of detected acceleration, a power change relay is turned on to change to the power source from the low voltage charge device after voltage of the smoothing condenser is reduced, thereby connecting the low voltage to the motor drive circuit.

Abstract: A pulse active steering control system and method for use in a motor vehicle for improving vehicle stability by reducing a likelihood for rollover and/or skidding sends pulses to the steerable wheels whenever a rollover coefficient and/or the difference between the estimated and actual yaw rate is outside a predetermined range. The pulses are asymmetrical in the form of a smooth curve with a gradually increasing rapid rising edge and a slower falling edge and provide steering input that, along with the driver steering input, returns the rollover coefficient and/or yaw rate to the predetermined range to reduce the likelihood of rollover and/or skidding.

Abstract: Sinusoidal signals (S1, S2) having a phase difference of 120° are output from two magnetic sensors in accordance with rotation of an input shaft. A first rotation angle computation unit computes a rotation angle ?(n) on the basis of output signals S1(n), S1(n?1), S2(n), S2(n?1) from the magnetic sensors, which are sampled at two sampling timings. At this time, the first rotation angle computation unit computes the rotation angle ?(n) on the assumption that there are no variations of amplitudes of the output signals (S1, S2) from each one of the two sensors due to temperature changes between the two sampling timings.

Abstract: Rotation angle computation modes include a normal mode and a simple mode. In normal mode, a rotation angle of an input shaft is computed based on output signals from first and second magnetic sensors, which are sampled at two sampling timings. In simple mode, the rotation angle of the input shaft is computed based on the output signals from the first and second magnetic sensors, which are sampled at one sampling timing, and an amplitude ratio between the output signals from the magnetic sensors set in advance. After a power supply is turned on, the rotation angle is computed in the simple mode until a condition that the rotation angle of the input shaft can be computed in the normal mode even if the immediately preceding value of the rotation angle of the input shaft is not present is satisfied. Then, the rotation angle is computed in the normal mode.

Abstract: If the main electric power source has failed, an assist control portion shifts the characteristic of an assist map in which the steering torque and the target current are connected in a relation by one step of shift in a direction of increase of the steering torque each time a steering operation that satisfies a steering operation criterion condition is performed. This allows a driver to feel a decline in the steering assist force each time of performing steering operation and therefore become aware of the abnormality. Besides, an upper-limit current of the assist map may be reduced each time the steering operation that satisfies the steering operation criterion condition is performed. Besides, an upper-limit electric power of an electric motor may be reduced each time the steering operation that satisfies the steering operation criterion condition is performed.

Abstract: A vehicle steering apparatus in which a mechanical coupling between a steering member and steered wheels is uncoupled, includes a steering actuator for driving a steered mechanism and a control unit for drive-controlling the steering actuator. The control unit reduces steering-stiffness using a PID control portion for drive-controlling the steering actuator according to a deviation between a target steered angle and a steered-angle detected by the steered angle sensor. A gain setting portion sets gains of the PID control portion to be relatively low when a predetermined condition is satisfied.

Abstract: A control system for controlling a steering system is provided. The control system includes a first module that determines a position control value based on a handwheel position. A second module generates a torque command based on the position control value to simulate an end of travel stop in the steering system.

Abstract: A method for supplying power to an electrically assisted steering system is described. In one example, the method adjusts alternator field current to increase energy supplied to the electrically assisted steering system in response to an automatic engine stop request. The method may improve operation of the electrically assisted steering system.

Abstract: The processing means, which control the power assisted steering motor (8), determine and give consideration to a first steering angle signal (A) determined as a function of the calculation or measurement of the force or torque delivered by the power assisted steering motor (8) and possibly of the steering torque or force applied by the driver to the steering wheel (2), a second steering angle signal (B) determined as a function of the calculation of the measurement of the angular position of the power assisted steering motor (8), a third signal (C) of the “index” type, that is to say of the type emitted for certain angular positions of the steering system (21), a convergence signal (D) indicative of the convergence of the steering angle calculations, and a confirmation signal (E) confirming the calculation of the steering angle, the convergence signal (D) being produced thanks to the signal (C) of “index” type to indicate a confidence level on the estimated steering angle value.

Abstract: [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.

Abstract: An electronic control unit determines the steering direction of rear wheels on the basis of the turning operation direction of a steering wheel when a detected vehicle speed is “0”, i.e. when the vehicle is stopped. If the steering direction of the rear wheels is a return-side steering direction to obtain a neutral steering position, the unit operates a rear wheel-side steering mechanism by driving and controlling an electric motor, whereby allowing return-side stationary steering for the rear wheels.

Abstract: An electric power steering system for a vehicle includes a steering mechanism coupling a steering wheel to a steerable element. A first actuator is in communication with a controller and operatively connected to the steering mechanism for assisting movement of the steerable element in response to a first signal from the controller. The system also includes a second actuator in communication with the controller, separate from the first actuator, and operatively connected to the steering mechanism between the first actuator and the steering wheel for superimposing torque in response to a second signal from the controller.

Abstract: The absolute value of a steering torque detected by a steering torque sensor is compared with a predetermined threshold. When the absolute value of the detected steering torque is smaller than the threshold, a steering reaction force is controlled on the basis of the steering torque; whereas, when the absolute value of the detected steering torque is larger than or equal to the threshold, the steering reaction force is controlled using a detected reaction motor current value as a reference value.

Abstract: The invention relates to a power assisted steering system (21) that includes an electric assist motor (22) arranged to assist the manual force exerted by a driver on the steering wheel of the automobile, a processing means (23) arranged to control the electric assist motor (22), the processing means (23) including a means (28) for predetermining a signal (S3) for controlling the electric assist motor on the basis of a first operation signal (S1) determined on the basis of the angular position of the electric assist motor, and a second operation signal (S2) determined on the basis of the measurement or calculation of the angular acceleration of the electric assist motor and the measurement or calculation of the assistance torque output by the electric assist motor.

Abstract: An electromechanical steering system for attachment to a manually operated wheelchair, the electromechanical steering system including: an input device arranged to develop an input signal, a motor and a wheel steering system driven by the motor and arranged to communicate with a wheel of the manually operated wheelchair to adjust a steering direction of the wheel based on the input signal.

Abstract: The present invention relates to a power steering system for a vehicle provided with means for actuating the stop & start function in a moving vehicle, especially an industrial or commercial or special vehicle, said vehicle being equipped with hybrid drive of the parallel type, comprising a thermal engine (1), an electric motor-generator (2), a single clutch unit (3) placed between the two engines, a transmission system (6) comprising an automated manual transmission, the method comprising the steps of enabling of the stop phase, activation of the stop phase, maintaining of the stop phase, activation of the start phase, the system comprising a hybrid power steering with coupling of a hydraulic power steering controlled by the thermal engine, and an electric power steering controlled by a control system (EPS) of the electric power steering.

Abstract: In a vehicle driving assistance apparatus having an electric motor to impart steering torque to the driver and a driving control unit that conducts collision avoidance assistance control and other steering control including lane departure prevention control, power steering control and parking assistance control for providing assistance during parking of the vehicle, when a warning for alerting the driver is made by imparting torque to the steering wheel via the motor, the control input of the other steering control is suppressed, i.e. is reduced during either the first predetermined time before warning or the second predetermined time after warning. Owing to this configuration, the driver can be enabled to perceive the warning without fail even when another steering control is performed in parallel.

Abstract: In a vehicle control apparatus employing a first speed self-adjustment control system configured to control a speed of a host vehicle based on a first command value, in a manner so as to maintain a distance of the host vehicle from a preceding vehicle or to maintain a set speed, a second speed self-adjustment control system is provided for controlling the host vehicle's speed based on a second command value determined based on information about a lateral acceleration acting on the host vehicle. Also provided is a deceleration selector configured to select either one of the first and second command values, which selected command value produces a greater deceleration exerted on the host vehicle. A control unit is configured to control the host vehicle's speed by driving an actuator based on the selected command value.

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 is selected, 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: An electric power steering apparatus (1) comprises a control device (12), which controls driving of an electric motor (18) based on the detection signals from a rotational position-detecting sensor (72; 72A), which detects the rotational position of the rotor (64) of the electric motor (18), and a steering status detecting sensor (11; 11A). The control device (12) is housed in a housing (100) that is partitioned by a first housing (23), which is at least a portion of the motor housing (25) for the electric motor (18), and a second housing (24; 24A; 24B) that touches the first housing (23). At least one of the rotational position-detecting sensor (72; 72A) and steering state detecting sensor (11; 11A) is connected to the control device (12) by means of only a signal wire (81; 134) inside the first housing (23) or the second housing (24; 24A; 24B).

Abstract: A controller applies slight rotational torque to a drive gear of a reduction mechanism also in a predetermined range in which a motor does not produce any steering operation assist force. That is, the motor is caused to produce slight rotational torque not enough to drive a driven gear, and the rotational torque direction is reversed under a given condition. Accordingly, a backlash between the drive gear and the driven gear is eliminated.

Abstract: A method for controlling a vehicle comprises operating at least one friction control device in a first friction mode, said at least one friction control device comprising one of a suspension damper, a lower control arm ball joint, a strut bearing, a steering rack guide, and an outer tie rod ball joint. The method further comprises changing operation of said at least one friction control device from the first friction mode to a second friction mode.

Abstract: Torque sensor has: magnetic member; first yoke member having (a) first nail portions arranged concentrically to face the magnetic member in radial direction and (b) first ring portion; second yoke member having (c) second nail portions arranged concentrically so that the first and second nail portions are circumferentially alternately arranged and the second nail portions face the magnetic member in radial direction and (d) second ring portion; first magnetic flux concentration ring provided between the first and second ring portions; second magnetic flux concentration ring provided between the second ring portion and the first magnetic flux concentration ring; and magnetic sensor. The first and second magnetic flux concentration rings and the first and second ring portions are arranged in layers in radial direction. A part or all of axial direction area of the first and second magnetic flux concentration rings is surrounded and shielded by the second ring portion.

Abstract: Torque sensor detects torque of steering shaft formed by first and second shafts which are connected through torsion bar. Torque sensor has: a magnetic member provided at the first shaft and having magnetic poles alternately arranged in circumferential direction concentrically with rotation axis; a first yoke member provided at the second shaft and having (a) first nail portions arranged concentrically with the rotation axis and facing the magnetic member in radial direction and (b) a first ring portion; a second yoke member provided at the second shaft and having (c) second nail portions arranged concentrically with the rotation axis so that the first and second nail portions are alternately arranged in the circumferential direction and the second nail portions face the magnetic member in the radial direction and (d) a second ring portion arranged to be separated from and face the first ring portion; and a magnetic sensor.

Abstract: A permanent magnet includes magnetic poles that are arranged so as to alternate in polarity in the circumferential direction of the axis of rotation. The magnet is attached to one of a pair of rotatable members. The rotatable members are relatively rotatable about an axis of rotation. A magnetic flux inducing ring, including an annular ring body and a plurality of protrusions protruding from the ring body, is attached to the other rotatable member. A plurality of magnetic sensors is arranged adjacent to the ring body. A first facing portion and a second facing portion, each for inducing a part of a magnetic flux of the ring body, are provided and do not rotate with the permanent magnet and the magnetic flux inducing ring.

Abstract: A steering apparatus includes a rotatable steering shaft having an exterior, an input end for connecting a steering member and an output end for connecting to at least one steerable wheel of a vehicle. An electric motor is operatively connected to the steering shaft for rotating the steering shaft. The shaft is magnetized and serves as a torque sensor transducer. At least one magnetic field sensor is adjacent to the exterior of the steering shaft. The steering shaft and the at least one magnetic field sensor form a torque sensor for sensing torque applied to the steering shaft by the manually operable steering member and provide a signal to operate the electric motor to assist steering of the steering shaft by the manually operable steering member.

Abstract: Method, system and non-transitory computer-readable medium for fail-safe performance of a lane centering system. An electrical power steering (EPS) system of a vehicle is monitored for a failure and operation of the lane centering system is switched to a differential braking controller to output differential braking commands to a differential breaking system upon determining that a failure of the EPS system has occurred, where the output braking commands direct the differential braking system to apply force a brake for a wheel of vehicle, such by the applied braking force the vehicle follows a desired path determined for a lane centering operation.

Abstract: A method for securing the assistance torque (15) supplied by an electric assistance motor (8) in a motor vehicle power steering system includes the steps of: estimating the force on the steering system rack from the torque exerted by the driver on the steering wheel (2), from the assistance torque (15), and optionally from other parameters such as the speed of the electric assistance motor; comparing a target assistance torque with an authorized assistance range, defined with respect to the estimated rack force (17) at any moment, and in the event the target assistance torque is maintained above predefined limits for a predefined duration, correcting and optionally interrupting the power steering.

Abstract: According a method of protecting a motor-driven power steering system from overheat, it is possible to prevent a steering motor and an ECU from being broken by overheat by controlling electric current supplied to the steering motor, by calculating an engine stop time from radiation temperature maps stored in a memory and changes in temperature of a temperature sensor when the engine having been stopped restarts without operating a specific protection logic when the engine stops, and calculating temperature of the steering motor and the ECU from the radiation temperature maps and the engine stop time.

Abstract: An electric power assisted steering system for a vehicle, comprising: a steering mechanism which operatively connects a steering wheel to road wheels of the vehicle, a torque sensor arranged to, in use, produce a torque signal indicative of the torque carried by a portion of the steering mechanism, an electric motor operatively connected to the steering mechanism, a signal processing unit arranged to, in use, produce from the torque signal a torque demand signal representative of a torque to be applied to the steering mechanism by the motor, the signal processing unit comprising a first calculating unit arranged to calculate an initial torque demand signal dependent on the torque signal, and a second calculating unit arranged to, in use, calculate a torque damping signal indicative of an amount the initial torque signal is to be damped in order to generate the torque demand signal, and a motor drive stage arranged to provide, in use, a drive current to the motor responsive to the torque demand signal, in whic

Abstract: Provided are a device and method of stopping an induction motor. The includes: a frequency commanding unit for generating an operating frequency corresponding to a rotational speed command of the induction motor; a q-axis and d-axis V/F converter for outputting a first q-axis voltage (Vq1) proportional to the generated operating frequency and a first d-axis voltage (Vd1) proportional to a 0 frequency; a q-axis PI current controller for outputting a second q-axis voltage (Vq2) for stopping the induction motor when the operating frequency reaches a stopping frequency; a d-axis PI current controller for outputting a second d-axis voltage (Vd2) for stopping the induction motor when the operating frequency reaches the stopping frequency; and a selection unit for selecting and outputting the first q-axis and d-axis voltages (Vq1 and Vd1) or the second q-axis and d-axis voltages (Vq2 and Vd2) according to the operating frequency generated by the frequency commanding unit.

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.