Electric power steering system
First Claim
1. An electric power steering system comprising:
- a motor that is a source of generating steering assist force that is applied to a steering mechanism of a vehicle; and
a controller that controls the motor in response to a vehicle steering operation, the controller includinga first computing unit that computes a basic control component of the steering assist force to be applied to the steering mechanism based on at least a steering torque, anda second computing unit that computes a correction control component for the basic control component through feedback control for causing an actual rotation angle of a rotary shaft that rotates based on a steered angle of steered wheels to coincide with a target rotation angle computed based on at least the steering torque, whereinthe second computing unit decreases at least a magnitude of the steering torque used to compute the target rotation angle and then computes the correction control component, to increase a steering reactive force with an increase in a lateral acceleration applied to the vehicle.
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Accused Products
Abstract
In an electric power steering system, a vehicle reactive force model computes a correction spring reactive torque in such a manner that an elasticity component included in a steering reactive force is increased with an increase in a lateral acceleration. As the lateral acceleration increases, an increase in a basic drive torque is suppressed by a larger amount. By an amount by which the magnitude of the basic drive torque is suppressed, a target pinion angle computed by a target pinion angle computing unit decreases and a correction component for a basic assist component is decreased. A steering assist force is decreased, and a steering reactive force is increased with a decrease in the steering assist force. Thus, it is possible to obtain an appropriate steering reactive force based on the magnitude of the lateral acceleration.
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Citations
4 Claims
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1. An electric power steering system comprising:
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a motor that is a source of generating steering assist force that is applied to a steering mechanism of a vehicle; and a controller that controls the motor in response to a vehicle steering operation, the controller including a first computing unit that computes a basic control component of the steering assist force to be applied to the steering mechanism based on at least a steering torque, and a second computing unit that computes a correction control component for the basic control component through feedback control for causing an actual rotation angle of a rotary shaft that rotates based on a steered angle of steered wheels to coincide with a target rotation angle computed based on at least the steering torque, wherein the second computing unit decreases at least a magnitude of the steering torque used to compute the target rotation angle and then computes the correction control component, to increase a steering reactive force with an increase in a lateral acceleration applied to the vehicle. - View Dependent Claims (2, 3, 4)
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Specification