Steering characteristic control apparatus and method for a vehicle
First Claim
1. A steering characteristic control apparatus for a vehicle, comprising:
- a braking mechanism capable of braking left and right wheels of said vehicle separately from each other;
steering characteristic determination means for estimating a steering characteristic of said vehicle upon turning of said vehicle;
steering characteristic control means for starting, when it is determined by said steering characteristic determination means that the steering characteristic of said vehicle exhibits an excessive oversteer or understeer state exceeding a control start criterion, steering characteristic control of controlling said braking mechanism so as to apply braking force to one of said left and right wheels to adjust the steering characteristic to the neutral steering side and ending the steering characteristic control when it is determined by said steering characteristic determination means during the steering characteristic control that the steering characteristic of said vehicle is stabilized within a control end criterion on the neutral steering side with respect to the control start criterion;
road surface μ
determination means for determining a road surface μ
state of a road surface of the road on which said vehicle travels; and
turning determination means for determining whether turning of said vehicle is steady turning or non-steady turning represented by a lane change;
a low μ
road control end criterion for being used when it is determined by said turning determination means that the turning of said vehicle is the steady turning and said road surface μ
estimation means estimates that the road surface is a low μ
road, a high μ
road control end criterion for being used when it is determined by said turning determination means that the turning of said vehicle is the steady turning and said road surface μ
estimation means estimates that the road surface is a high μ
road and a non-steady turning control end criterion for being used when it is determined by said turning determination means that the turning of said vehicle is the non-steady turning being provided as the control end criterion;
the low μ
road control end criterion, high μ
road control end criterion and non-steady turning control end criterion having values relating to the vehicle behavior stability;
the low μ
road control end criterion being set to a value higher in the vehicle behavior stability than that of the high μ
road control end criterion;
the non-steady turning control end criterion being set to a value lower in the vehicle behavior stability than that of the low μ
road control end criterion but higher in the vehicle behavior stability than that of the high μ
road control end criterion.
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Accused Products
Abstract
A steering characteristic control apparatus and method for a vehicle is disclosed which can carry out behavior control of the vehicle regarding a steering characteristic and so forth appropriately in accordance with the type of turning and the road surface situation. To this end, if the steering characteristic of the vehicle is placed into an oversteer or understeer state exceeding a reference level, then the control end condition when the steering characteristic is controlled to the neutral steer side by control of a braking mechanism is set in accordance with an estimated road surface μ state and the type of turning (steady turning or non-steady turning) of the vehicle. Upon steady turning, during traveling on a low μ road, it is set as the control end condition that the stability of the vehicle behavior is restored sufficiently, but during traveling on a high μ road, it is set as the condition that the stability of the vehicle behavior is restored to some degree so that the control can be ended rapidly. Upon non-steady turning, the condition is set such that the stability of the vehicle behavior is higher than that upon steady turning during traveling on a high μ road but lower than that upon steady turning during traveling on a low μ road.
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Citations
12 Claims
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1. A steering characteristic control apparatus for a vehicle, comprising:
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a braking mechanism capable of braking left and right wheels of said vehicle separately from each other; steering characteristic determination means for estimating a steering characteristic of said vehicle upon turning of said vehicle; steering characteristic control means for starting, when it is determined by said steering characteristic determination means that the steering characteristic of said vehicle exhibits an excessive oversteer or understeer state exceeding a control start criterion, steering characteristic control of controlling said braking mechanism so as to apply braking force to one of said left and right wheels to adjust the steering characteristic to the neutral steering side and ending the steering characteristic control when it is determined by said steering characteristic determination means during the steering characteristic control that the steering characteristic of said vehicle is stabilized within a control end criterion on the neutral steering side with respect to the control start criterion; road surface μ
determination means for determining a road surface μ
state of a road surface of the road on which said vehicle travels; andturning determination means for determining whether turning of said vehicle is steady turning or non-steady turning represented by a lane change; a low μ
road control end criterion for being used when it is determined by said turning determination means that the turning of said vehicle is the steady turning and said road surface μ
estimation means estimates that the road surface is a low μ
road, a high μ
road control end criterion for being used when it is determined by said turning determination means that the turning of said vehicle is the steady turning and said road surface μ
estimation means estimates that the road surface is a high μ
road and a non-steady turning control end criterion for being used when it is determined by said turning determination means that the turning of said vehicle is the non-steady turning being provided as the control end criterion;the low μ
road control end criterion, high μ
road control end criterion and non-steady turning control end criterion having values relating to the vehicle behavior stability;the low μ
road control end criterion being set to a value higher in the vehicle behavior stability than that of the high μ
road control end criterion;the non-steady turning control end criterion being set to a value lower in the vehicle behavior stability than that of the low μ
road control end criterion but higher in the vehicle behavior stability than that of the high μ
road control end criterion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A steering characteristic control method for a vehicle which includes a braking mechanism capable of braking left and right wheels of said vehicle separately from each other, and steering characteristic determination means for estimating a steering characteristic of said vehicle upon turning of said vehicle, wherein steering characteristic control of controlling said braking mechanism so as to apply braking force to one of said left and right wheels to adjust the steering characteristic to the neutral steering side is started when it is determined by said steering characteristic determination means that the steering characteristic of said vehicle exhibits an excessive oversteer or understeer state exceeding a control start criterion and then the steering characteristic control is ended when it is determined by said steering characteristic determination means during the steering characteristic control that the steering characteristic of said vehicle is stabilized within a control end criterion on the neutral steering side with respect to the control start criterion, comprising:
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a road surface μ
determination step of determining a road surface μ
state of a road surface of the road on which said vehicle travels;a turning determination step of determining whether turning of said vehicle is steady turning or non-steady turning represented by a lane change; and an end determination step of determining, when it is determined at the turning determination step that the turning of said vehicle is the steady turning and it is estimated at the road surface μ
estimation step that the road surface is a low μ
road, an end of the steering characteristic control using a low μ
road control end criterion as the control end criterion, determining, when it is determined at the turning determination step that the turning of said vehicle is the steady turning and it is estimated at the road surface μ
estimation step that the road surface is a high μ
road, an end of the steering characteristic control using a high μ
road control end criterion as the control end criterion, and determining, when it is determined at the turning determination step that the turning of said vehicle is the non-steady turning, an end of the steering characteristic control using a non-steady turning control end criterion as the control end criterion;the low μ
road control end criterion, high μ
road control end criterion and non-steady turning control end criterion having values relating to the vehicle behavior stability;the low μ
road control end criterion being set to a value higher in the vehicle behavior stability than that of the high μ
road control end criterion;the non-steady turning control end criterion being set to a value lower in the vehicle behavior stability than that of the low μ
road control end criterion but higher in the vehicle behavior stability than that of the high μ
road control end criterion.
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Specification