Adaptive variable effort power steering system
First Claim
1. An adaptive variable power steering system for a motor vehicle having steerable wheels for operating on roads having variable road surface friction, the vehicle having a low friction road surface vehicle handling control responsive to reduction in friction between the steerable wheels and the road surface, with means for generating a handling limit signal, the power steering system comprising, in combination:
- means for generating an assist torque in response to sensed handwheel input torque; and
means responsive to the low friction road surface vehicle handling control to reduce the assist torque during the generation of the handling limit signal.
10 Assignments
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Accused Products
Abstract
An adaptive, variable effort power steering system is responsive signals from one or more low friction road surface vehicle handling controls which indicate when the system has become active in modifying handling, and thus indicates the existence of a near limit or at limit vehicle handling situation. Such controls include anti-lock braking systems (ABS), traction control systems (TCS) and integrated chassis control systems (ICCS). When such a handling limit signal is received, the power steering system responds by decreasing steering assist to provide a more "manual" steering feel as long as the handling limit situation is indicated. The handling limit signal may be a binary signal, indicating activity or no activity of an anti-lock brake system, traction control system or a chassis control system such a yaw rate control. Alternatively, or in addition, the handling limit signal may be a magnitude signal indicating the degree or amount of yaw rate error, lateral acceleration error, wheel slip or vehicle side-slip and thus potentially anticipating the vehicle handling limit as indicated by a binary signal. If binary and magnitude signals are used together, the magnitude signal is preferably used as an anticipatory signal with a partial and growing correction to smooth the application of the full correction signaled by the binary signal.
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Citations
11 Claims
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1. An adaptive variable power steering system for a motor vehicle having steerable wheels for operating on roads having variable road surface friction, the vehicle having a low friction road surface vehicle handling control responsive to reduction in friction between the steerable wheels and the road surface, with means for generating a handling limit signal, the power steering system comprising, in combination:
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means for generating an assist torque in response to sensed handwheel input torque; and means responsive to the low friction road surface vehicle handling control to reduce the assist torque during the generation of the handling limit signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification