Abstract: Steering torque sensor detects steering torque manually applied to the vehicle's steering system. Control unit sets a target motor current corresponding at least to the steering torque detected by the steering torque sensor and has a plurality of steering assist modes to which are allocated different characteristics of a target motor current for an assisting motor. The control unit include a mode switching unit that, in response to a mode setting instruction from a vehicle operator, effects a change between the steering assist modes when the steering torque sensor is in its dead zone and no target motor current signal is being generated. Thus, the driver is allowed to continue driving with a steering characteristic fitting his or her preference, and hence good steering feel and vehicle behavior, even when a steering characteristic change takes place during travel of the vehicle.

Abstract: An electric power steering apparatus includes a proportional plus integral control section incorporated in a control unit for achieving proportional plus integral control action of an offset between a target motor current to be supplied to an electric motor and a motor current actually flowing in the electric motor, and an overshoot diminishing section for controlling at least one of proportional sensitivity and integral gain of the proportional plus integral control section so as to diminish overshoot of the motor current occurring when the steering wheel is quickly turned until it reaches a steering lock position. With this arrangement, semiconductor devices used in the control unit for driving the electric motor are protected against damage caused when subjected to an overload resulting from the overshoot of the motor current.

Abstract: In a motor drive apparatus, a motor drive circuit includes an H bridge circuit composed of four field effect transistors or FETs, and resistors each having electrical resistance sufficiently higher than that of each of the FETs which would be presented when the FET has an ON-state trouble. These resistors are connected in parallel to the respective FETs. To perform a ON-state trouble detecting test on the individual FETs, an OFF signal is fed to all the FETs. If all the EFTS are free of the ON-state trouble, electric potential, representing a result of higher potential of a battery being divided by the resistors, appears at two input terminals of an electric motor connected to the motor drive circuit. If two of the FETs, having their drains connected to a higher-potential electrode of the battery, have the ON-state trouble, the higher potential of the battery appears at the two terminals of the electric motor.

Abstract: An electric power steering apparatus comprises a motor for applying an auxiliary torque to a steering system, a steering torque sensor for detecting a steering torque in the steering system and a control unit for drive-controlling the motor based on at least a steering torque signal from the steering torque sensor. The control unit includes a motor control unit and a failure detecting unit for detecting a failure of the control unit. Based on a failure detection signal from the failure detecting unit, the motor drive control unit switches over from a normal mode in which no failure exists in the apparatus to a first failure mode in which a certain failure exists in the apparatus and an assist ratio is changed to about half of that of the normal mode.

Abstract: An electric power steering apparatus having a control unit for controlling a motor for applying an assist torque to a steering system on the basis of a steering torque of the steering system. The control unit has a drive signal fading part for generating a drive current signal on the basis of a deviation signal expressing the deviation between a target current set in correspondence with a steering torque and a detected motor current detected by a motor current detector and gradually decreasing a drive current value with time to zero when a fadeout request signal is supplied to it. Thus in an electric power steering apparatus constructed to gradually decrease a steering assist force being supplied from a motor when an ignition switch is turned off, even if an error arises in a detected motor current value as a result of a fall in the voltage of a battery power supply, the steering assist force can be decreased correctly.

Abstract: A control unit of an electric power steering apparatus has an overload preventing part having the function of decreasing the current supplied to a motor of the electric power steering apparatus when a state such that a steering torque acting on the steering system is above a predetermined value and the steering speed of the steering system is below a predetermined value has continued for a predetermined time or having the function of immediately decreasing the current supplied to the motor when the steering speed of the steering system is below a predetermined value and the steering torque acting on the steering system is above a first predetermined value and decreasing the current supplied to the motor when a state such that the steering speed is below a predetermined value and the steering torque is above a second predetermined value smaller than the first predetermined value has continued for a predetermined time.

Abstract: An electric power steering apparatus includes a control unit for controlling a steering assist from an electric motor in accordance with steering torque detected by a torque detector. The control unit includes a plurality of assist mode generators to which are allocated different characteristics of target current to provide different steering characteristics, and any one of the assist mode generators can be switchably selected depending on a predetermined condition. All of the assist mode generators are set in such a manner that the respective allocated characteristics of target current become substantially uniform in a high-velocity driving condition.

Abstract: Control unit has a plurality of steering assist modes to which are allocated different characteristics of a target motor current for an assisting motor. Engine rotation sensor detects a current number of rotations of a vehicle engine. Mode switching unit effects a change between the steering assist modes only when the detected vehicle velocity is below a predetermined reference velocity representative of a substantially stationary condition of the vehicle and simultaneously the detected number of rotations of the engine is below a predetermined value. Thus, a change in steering characteristic is permitted only when the engine rotation sensor indicates that the vehicle is in the substantially stationary condition. This way, even with a malfunctioning velocity sensor, it is always possible to avoid an unwanted deterioration in driver's steering feel that would be caused by the steering characteristic change.

Abstract: A vehicular motor driving apparatus includes a control unit 15 for drive-controlling a motor by PWM-drive-controlling a motor driving circuit based on a motor starting signal. The control unit has a drive controller for setting a drive frequency of a PWM-drive control signal to be an integral multiple of or (integer+0.5) times a channel frequency interval of channel frequencies allotted for AM radio broadcasts. As a result, radiation noise associated with harmonics of the PWM-drive control signal, when coincided with the channel frequencies used by AM radio broadcast stations, is removed along with the channel frequencies through radio receiver detection. When the radiation noise does not coincide with the in-use channel frequencies, it is offset by the channel frequency interval therefrom, thereby preventing its reception.

Abstract: An electric power steering apparatus includes a control unit having a sensor fault detecting section, a first drive control signal generating section, a second drive control signal generating section, and a motor drive control mode switching section. When the sensor fault detecting section does not detect any faulty sensor, operation of an electric motor is feedback-controlled in such a manner that an offset between a target current set in accordance with a steering torque and a motor current becomes zero, and the motor applies a steering assist torque to the steering system on the basis of a first drive control signal supplied from the first drive control signal generating section.

Abstract: An electric power steering apparatus includes a control unit for controlling a motor drive circuit which drives an electric motor on the basis of a steering torque signal supplied from a steering torque sensor. The control unit includes a center value compensating circuit for compensating for the offset of a center value of the steering torque sensor, and a direction inhibiting circuit for inhibiting supply of a motor control signal to the motor drive circuit on the basis of the steering torque signal. The direction inhibiting circuit has a reference value changing section for changing operation reference values in left and right directions of the steering torque in response to the offset of the center value. The reference value changing section generates left and right operation reference values corresponding to a center value signal supplied from the center value compensating circuit.

Abstract: An electric power steering device for directly applying the power of an electric motor as an auxiliary steering power to a steering system to lower a steering force required of the driver, wherein a current detecting element in a motor current detecting unit is connected in series with the motor, and a drive control unit is operable to always drive, by a PWM signal, that side of switching elements of a bridge circuit to which the motor is connected. With this construction, a high-frequency pulse noise generated upon the PWM driving of the the switching element is absorbed by an inductance in the motor and hence a high-frequency pulse noise detected by the current detecting element can be controlled at an extremely small level. Thus, the electric power steering device can prevent generation of abnormal noises from the motor and oscillation or hunting of the steering system and provide stable steering characteristics.

Abstract: In a controller of an electric power steering apparatus for use with an automotive vehicle, a regenerating condition determining section determines whether or not a motor of the vehicle is in a regenerating condition, and a regeneration control signal generating section generates a regeneration control signal to control the regenerating condition of the motor. A switching section selects between the motor control signal and the regeneration control signal in accordance with a result of determination by the regenerating condition determining section. With this arrangement, a motor current including a regenerative current that is caused to flow in the motor in response to a vehicle driver effecting during-stoppage steering maneuvering and then releasing a steering wheel can be controlled independently of a feedback loop of the controller.

Abstract: An electric power steering apparatus, which provides a steering assist of an electric motor directly to a vehicle steering system to reduce necessary steering power to be applied by a vehicle driver, is provided with a control unit which includes a proportion-coefficient and integration-coefficient setting section for, on the basis of a velocity of the vehicle detected by a velocity sensor, setting sensitivity of a proportioning element and integration gain of an integrating element in such a manner that they take greater values during high-velocity running of the vehicle than during low-velocity running of vehicle. This prevents occurrence of unwanted noises and vibrations during low-velocity running of the vehicle and also enhances steering response during high-velocity running of the vehicle, thus always providing an optimum steering feeling in changing running conditions of the vehicle.

Abstract: An electric power steering apparatus provides a steering assist of an electric motor directly to a vehicle steering system so as to reduce necessary steering power to be applied by a driver, and it is provided with a control unit including a phase compensation section implemented by software. The gain and phase of a steering torque signal from a steering torque sensor can be accurately set which correspond to the running and steering states of the vehicle, on the basis of a vehicle velocity signal from a vehicle velocity sensor. Thus, the gain in a high vehicle velocity condition and in such a frequency range outside the steering region can be controlled to substantially decrease so as to avoid parasitic oscillation and hence prevent the occurrence of magnetostrictive sound and hunting due to the parasitic oscillation. Accordingly, optimum steering feel can be achieved which corresponds to the states of the vehicle.

Abstract: An electric power steering system is disclosed which includes an electric motor adapted to supply steering assist directly to the steering system to thereby reduce the steering torque to be exerted to the system by a driver. The steering system includes a phase compensative device which is formed of a phase delay circuit, or the phase delay circuit and a low-pass filter connected in series thereto, and is positioned in a loop connecting a motor current detector in the steering system and a drive controller in a control block, so that high-frequency components may be removed from motor current signals in the feedback loop. As a result, it is possible to suppress lag of the phases of the signals and hence to prevent parasitic oscillations, leading to the steering system being capable of providing steering assist most suited to particular steering operations and comfortable steering feel to a driver.

Abstract: This invention is an electric power steering apparatus for applying the power of an electric motor to a steering system to reduce the steering torque, comprising a steering torque detection means, steering rotating speed detection means, a differential operation means, an electric motor control signal determination means, and an electric motor drive means.

Abstract: An electrically operated power steering apparatus basically has a steering torque sensor, a steering rotational speed sensor, and preferably a vehicle sensor. A controller outputs a motor control signal based on a steering torque, a steering rotational speed, and a vehicle speed which are detected by the steering torque sensor, the steering rotational speed sensor, and the vehicle sensor, respectively. The motor control signal is applied to control a motor driver to output a motor drive signal which energizes an electric motor to produce an assistive steering force or a braking force. The electrically operated power steering apparatus is effective to improve steering and returning characteristics of a steering system, and give the steering system a stable steering capability.

Abstract: An electrically operated power steering apparatus in a motor vehicle has a steering system for steering the motor vehicle, a steering torque detector for detecting a manual steering torque applied to the steering system, and an electric motor for generating an assistive torque to be transmitted as a steering assistive force to the steering system. An actual assistive torque detector detects an actual assistive steering torque which is actually transmitted from the electric motor to the steering system. A controller has at least a target assistive torque generator for generating a target value for an assistive torque to be generated by the electric motor depending on the manual steering torque detected by the steering torque detector, and generates a control signal based on the difference between the actual assistive steering torque detected by the actual assistive torque detector and the target value generated by the target assistive torque generator.