APPARATUS AND METHOD FOR CONTROLLING ELECTRIC POWER STEERING SYSTEM
First Claim
1. A control apparatus provided to an electric power steering system comprising:
- an input shaft connected to a steering wheel of a vehicle and rotated together with the steering wheel, being urged by a steering wheel torque that is an input caused by manipulation of the steering wheel;
a torque detector detecting torque applied to a torsion bar on the basis of a torsion angle of the torsion bar, the torsion bar being provided to a part of a torque transmission path for transmitting rotation of the input shaft to the steering wheel of the vehicle; and
a motor generating an assist steering force for assisting the manipulation of the steering wheel when the steering wheel is steered by the manipulation of the steering wheel,the apparatus controlling the assist steering force by controlling rotation of the motor, wherein;
the apparatus comprises;
a basic assist amount calculation section calculating a basic assist amount for assisting the manipulation of the steering wheel on the basis of a torque detected by the torque detector;
an assist compensation amount calculation section calculating an assist compensation amount for correcting the basic assist amount calculated by the basic assist amount calculation section;
an assist compensation correction section calculating a corrected assist amount by correcting the basic assist amount calculated by the basic assist amount calculation section on the basis of the assist compensation amount calculated by the assist compensation amount calculation section; and
a motor drive section driving the motor on the basis of the corrected assist amount from the assist amount correction section, andthe assist compensation amount calculation section is configured to;
use at least two kinds of input signals that reflect operations of the electric power steering system to calculate the assist compensation amount so as to meet both of the following specifications (a) and (b) which are;
(a) a forward input specification corresponding to characteristics of transmitting the steering wheel torque to a road surface in the electric power steering system, the characteristics being equal to those of the case where the motor is driven with no correction of the basic assist amount by the assist compensation amount; and
(b) a reverse input specification corresponding to characteristics of transmitting road-surface input torque that is a force received by the steering wheel from a road surface on which the vehicle runs, in the electric power steering system, the characteristics exhibiting more transmission of the road-surface input torque to the steering wheel than in the case where the motor is driven with no correction of the basic assist amount by the assist compensation amount, andcalculate an assist compensation amount suitable for a vehicle-state value that influences the transmission characteristics of the road-surface input torque to thereby suppress frequency alteration at a resonance point in the transmission characteristics, the frequency alteration being attributed to variation of the vehicle-state value.
1 Assignment
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Accused Products
Abstract
An electric power steering system includes a basic assist amount calculation section calculating a basic assist amount for assisting the manipulation of a steering wheel, and an assist compensation amount calculation section calculating an assist compensation amount for correcting the basic assist amount. The system includes an assist amount correction section calculating a corrected assist amount by correcting the basic assist amount based on the assist compensation amount, and a motor drive section driving a motor using the corrected assist amount. The assist compensation amount calculation section uses a reverse input specification that more transmits the signal components of specific frequency in road-surface input torque, to a steering wheel than in the case of using only the basic assist amount, and calculates the assist compensation amount suitable for a vehicle-state value, such as a steering torque, to suppress variation in the transmission characteristics due to variation of the vehicle-state value.
39 Citations
20 Claims
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1. A control apparatus provided to an electric power steering system comprising:
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an input shaft connected to a steering wheel of a vehicle and rotated together with the steering wheel, being urged by a steering wheel torque that is an input caused by manipulation of the steering wheel; a torque detector detecting torque applied to a torsion bar on the basis of a torsion angle of the torsion bar, the torsion bar being provided to a part of a torque transmission path for transmitting rotation of the input shaft to the steering wheel of the vehicle; and a motor generating an assist steering force for assisting the manipulation of the steering wheel when the steering wheel is steered by the manipulation of the steering wheel, the apparatus controlling the assist steering force by controlling rotation of the motor, wherein; the apparatus comprises; a basic assist amount calculation section calculating a basic assist amount for assisting the manipulation of the steering wheel on the basis of a torque detected by the torque detector; an assist compensation amount calculation section calculating an assist compensation amount for correcting the basic assist amount calculated by the basic assist amount calculation section; an assist compensation correction section calculating a corrected assist amount by correcting the basic assist amount calculated by the basic assist amount calculation section on the basis of the assist compensation amount calculated by the assist compensation amount calculation section; and a motor drive section driving the motor on the basis of the corrected assist amount from the assist amount correction section, and the assist compensation amount calculation section is configured to; use at least two kinds of input signals that reflect operations of the electric power steering system to calculate the assist compensation amount so as to meet both of the following specifications (a) and (b) which are; (a) a forward input specification corresponding to characteristics of transmitting the steering wheel torque to a road surface in the electric power steering system, the characteristics being equal to those of the case where the motor is driven with no correction of the basic assist amount by the assist compensation amount; and (b) a reverse input specification corresponding to characteristics of transmitting road-surface input torque that is a force received by the steering wheel from a road surface on which the vehicle runs, in the electric power steering system, the characteristics exhibiting more transmission of the road-surface input torque to the steering wheel than in the case where the motor is driven with no correction of the basic assist amount by the assist compensation amount, and calculate an assist compensation amount suitable for a vehicle-state value that influences the transmission characteristics of the road-surface input torque to thereby suppress frequency alteration at a resonance point in the transmission characteristics, the frequency alteration being attributed to variation of the vehicle-state value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 14, 15, 16, 17, 18, 19, 20)
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11. A control method provided to an electric power steering system comprising:
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an input shaft connected to a steering wheel of a vehicle and rotated together with the steering wheel, being urged by a steering wheel torque that is an input caused by manipulation of the steering wheel; a torque detector detecting torque applied to a torsion bar on the basis of a torsion angle of the torsion bar, the torsion bar being provided to a part of a torque transmission path for transmitting rotation of the input shaft to the steering wheel of the vehicle; and a motor generating an assist steering force for assisting the manipulation of the steering wheel when the steering wheel is steered by the manipulation of the steering wheel, and the method controlling the assist steering force by controlling rotation of the motor, wherein; the method comprises; a basic assist amount calculation step of calculating a basic assist amount for assisting the manipulation of the steering wheel on the basis of a torque detected by the torque detector; a compensation amount calculation step of calculating an assist compensation amount for correcting the calculated basic assist amount; a correction step of calculating a corrected assist amount by correcting the calculated basic assist amount on the basis of the calculated assist compensation amount; and a motor drive step of driving the motor on the basis of the corrected assist amount, and the assist compensation amount calculation step; uses at least two kinds of input signals that reflect operations of the electric power steering system to calculate the assist compensation amount so as to meet the following specifications (a) and (b) which are; (a) a forward input specification corresponding to characteristics of transmitting the steering wheel torque to a road surface in the electric power steering system, the characteristics being equal to those of the case where the motor is driven with no correction of the basic assist amount by the assist compensation amount; and (b) a reverse input specification corresponding to characteristics of transmitting road-surface input torque that is a force received by the steering wheel from a road surface on which the vehicle runs, in the electric power steering system, the characteristics exhibiting more transmission of the road-surface input torque to the steering wheel than in the case where the motor is driven with no correction of the basic assist amount by the assist compensation amount, and calculates an assist compensation amount suitable for a vehicle-state value that influences the transmission characteristics of the road-surface input torque to thereby suppress frequency alteration at a resonance point in the transmission characteristics, the frequency alteration being caused by variation of the vehicle-state value.
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12. An electric power steering system comprising:
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an input shaft connected to a steering wheel of a vehicle and rotated together with the steering wheel, being urged by a steering wheel torque that is an input caused by manipulation of the steering wheel; a torque detector detecting torque applied to a torsion bar on the basis of a torsion angle of the torsion bar, the torsion bar being provided to a part of a torque transmission path for transmitting rotation of the input shaft to the steering wheel of the vehicle; a motor generating an assist steering force for assisting the manipulation of the steering wheel by rotation when the steering wheel is steered by the manipulation of the steering wheel, and controlling the assist steering force through control of the rotation; a basic assist amount calculation section calculating a basic assist amount for assisting the manipulation of the steering wheel on the basis of a torque detected by the torque detector; an assist compensation amount calculation section calculating an assist compensation amount for correcting the basic assist amount calculated by the basic assist amount calculation section; an assist amount correction section calculating a corrected assist amount by correcting the basic assist amount calculated by the basic assist amount calculation section on the basis of the assist compensation amount calculated by the assist compensation amount calculation section; a motor drive section driving the motor on the basis of the corrected assist amount from the assist amount correction section, wherein, the assist compensation amount calculation section is configured to; use at least two kinds of input signals that reflect operations of the electric power steering system to calculate the assist compensation amount so as to meet the following specifications (a) and (b) which are; (a) a forward input specification corresponding to characteristics of transmitting the steering wheel torque to a road surface in the electric power steering system, the characteristics being equal to those of the case where the motor is driven with no correction of the basic assist amount by the assist compensation amount; and (b) a reverse input specification corresponding to characteristics of transmitting road-surface input torque that is a force received by the steering wheel from a road surface on which the vehicle runs, in the electric power steering system, the characteristics exhibiting more transmission of the road-surface input torque to the steering wheel than in the case where the motor is driven with no correction of the basic assist amount by the assist compensation amount, and calculate an assist compensation amount suitable for a vehicle-state value that influences the transmission characteristics of the road-surface input torque to thereby suppress frequency alteration at a resonance point in the transmission characteristics, the frequency alteration being attributed to variation of the vehicle-state value.
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Specification