Automotive control system providing anti-skid steering
First Claim
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1. A four wheel steering control system for an automotive vehicle which includes a primary steerable wheel turned by a manually operable vehicular steering mechanism, and a subsidiary steerable wheel, said control system comprising:
- a subsidiary wheel toe control mechanism operatingly connected to said subsidiary steerable wheel for controlling a toe angle according to a subsidiary wheel steering control signal, said subsidiary wheel toe control mechanism including a power assist cylinder for generating assistant force so as to turn said subsidiary wheel;
a steering wheel angle sensing means disposed adjacent to said manually operable steering mechanism for producing a steering wheel angle indicating signal representative of the magnitude of a manually entered steering demand for said primary steerable wheel;
a wheel speed monitoring means for monitoring the rotation speed of each of said primary and subsidiary steerable wheels for producing a wheel speed indicating signal;
means for deriving a calculated vehicle speed representing value on the basis of said wheel speed indicating signal from said wheel speed monitoring means, such that said calculated vehicle speed representing value is constantly held at a current value of said wheel speed indicating signal for a predetermined time interval when a speed difference between said wheel speed indicating signal and said calculated vehicle speed representing value is within a predetermined range, a velocity gradient for said calculated vehicle speed representing value is set to ta predetermined velocity gradient so as to decrease said speed difference with said predetermined velocity gradient when said speed difference exceeds said predetermined range at an expiration of said predetermined time interval or when said speed difference is less than said predetermined range at expiration of said predetermined time interval; and
a first control system for determining an optimal magnitude of said assistant force by said subsidiary wheel steering control signal derived on the basis of both said steering wheel angle indicating signal and said calculated vehicle speed representing value.
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Abstract
A control system for a four wheel steering system detects the occurrence of wheel slippage for sampling wheel speed data immediately before the occurrence of wheel slippage. The control system projects a vehicle speed on the basis of the sampled wheel speed data and a predetermined variation rate of the vehicle speed, and derives toe angle variation magnitude of a subsidiary steerable wheel on the basis of the projected vehicle speed and a steering angle of a primary steerable wheel.
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Citations
16 Claims
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1. A four wheel steering control system for an automotive vehicle which includes a primary steerable wheel turned by a manually operable vehicular steering mechanism, and a subsidiary steerable wheel, said control system comprising:
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a subsidiary wheel toe control mechanism operatingly connected to said subsidiary steerable wheel for controlling a toe angle according to a subsidiary wheel steering control signal, said subsidiary wheel toe control mechanism including a power assist cylinder for generating assistant force so as to turn said subsidiary wheel; a steering wheel angle sensing means disposed adjacent to said manually operable steering mechanism for producing a steering wheel angle indicating signal representative of the magnitude of a manually entered steering demand for said primary steerable wheel; a wheel speed monitoring means for monitoring the rotation speed of each of said primary and subsidiary steerable wheels for producing a wheel speed indicating signal; means for deriving a calculated vehicle speed representing value on the basis of said wheel speed indicating signal from said wheel speed monitoring means, such that said calculated vehicle speed representing value is constantly held at a current value of said wheel speed indicating signal for a predetermined time interval when a speed difference between said wheel speed indicating signal and said calculated vehicle speed representing value is within a predetermined range, a velocity gradient for said calculated vehicle speed representing value is set to ta predetermined velocity gradient so as to decrease said speed difference with said predetermined velocity gradient when said speed difference exceeds said predetermined range at an expiration of said predetermined time interval or when said speed difference is less than said predetermined range at expiration of said predetermined time interval; and a first control system for determining an optimal magnitude of said assistant force by said subsidiary wheel steering control signal derived on the basis of both said steering wheel angle indicating signal and said calculated vehicle speed representing value. - View Dependent Claims (2, 3)
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4. In a combination of a four wheel steering control system for an automotive vehicle which includes a primary steerable wheel turned by a manually operable vehicular steering mechanism, and a subsidiary steerable wheel, and an anti-skid brake control system which controls braking pressure applied for respective wheels on the basis of a wheel slippage derived on the basis of a wheel speed indicating signal value and a vehicle speed representing value, said four wheel steering control system comprises:
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a subsidiary wheel toe control mechanism operatingly connected to said subsidiary steerable wheel for controlling a toe angle according to a subsidiary wheel steering control signal, said subsidiary wheel toe control mechanism including a power assist cylinder for generating assistant force so as to turn said subsidiary wheel; a steering wheel angle sensing means disposed adjacent to said manually operable steering mechanism for producing a steering wheel angle indicating signal representative of the magnitude of a manually entered steering demand for said primary steerable wheel; a wheel speed monitoring means for monitoring the rotation speed of each of said primary and subsidiary steerable wheels for producing a wheel speed indicating signal; means for deriving a calculated vehicle speed representing value on the basis of said wheel speed indicating signal from said wheel speed monitoring means, such that said calculated vehicle speed representing value is constantly held at a current value of said wheel speed indicating signal for a predetermined time interval when a speed difference between said wheel speed indicating signal and said calculated vehicle speed representing value is within a predetermined range, a velocity gradient for said calculated vehicle speed representing value is set to a predetermined velocity gradient so as to decrease said speed difference with said predetermined velocity gradient when said speed difference exceeds said predetermined range at an expiration of said predetermined time interval or when said speed difference is less than said predetermined range at an expiration of said predetermined time interval; and a control unit for determining an optimal magnitude of said assistant force by said subsidiary wheel steering control signal derived on the basis of both of said steering wheel angle indicating signal and said calculated vehicle speed representing value.
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5. A steering control system for an automotive vehicle employing an assistant steering mechanism for applying assistant force to at least one of a steering mechanism turning front wheels and a steering mechanism turning rear wheels, on the basis of at least a steering wheel angle and a vehicle speed, comprising:
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a steering wheel angle sensor for monitoring said steering wheel angle, to generate a steering wheel angle indicating signal; means for monitoring each wheel speed of said wheels, to produce wheel speed indicating signals; means for deriving a calculated vehicle speed representing value on the basis of said wheel speed indicating signals from said wheel speed monitoring means, such that when a speed difference between a highest value of said wheel speed indicating signals and said calculated vehicle speed representing value is within a predetermined range, said calculated vehicle speed representing value is constantly held at a current highest value of said wheel speed indicating signals for a predetermined time interval and a velocity gradient for said calculated vehicle speed representing value is set to a predetermined velocity gradient so as to decrease said. speed difference with said predetermined velocity gradient when said speed difference exceeds said predetermined range at an expiration of said predetermined time interval or when said speed difference is less than said predetermined range at an expiration of said predetermined time interval; and a control unit for determining an optimal magnitude of said assistant force on the basis of both of said steering wheel angle indicating signal and said calculated vehicle speed representing value. - View Dependent Claims (6, 7, 8)
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9. A steering control system for an automotive vehicle employing an assistant steering mechanism for applying assistant force to at least one of a steering mechanism turning front wheels and a steering mechanism turning rear wheels, on the basis of at least a steering wheel angle and a vehicle speed, and an anti-skid brake control system for controlling behavior, comprising:
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a steering wheel angle sensor for monitoring said steering wheel angle, to generate a steering wheel angle indicating signal; means for monitoring each wheel speed of said wheels, to produce wheel speed indicating signals; means for deriving a calculated vehicle speed representing value on the basis of said wheel speed indicating signals from said wheel speed monitoring means, such that when a speed difference between a highest value of said wheel speed indicating signals and said calculated vehicle speed representing value is within a predetermined range, said calculated vehicle speed representing value is constantly held at a current highest value of said wheel speed indicating signals for a predetermined time interval and a velocity gradient for said calculated vehicle speed representing value is set to a predetermined velocity gradient so as to decrease said speed difference with said predetermined velocity gradient when said speed difference exceeds said predetermined range at an expiration of said predetermined time interval or when said speed difference is less than said predetermined range at an expiration of said predetermined time interval; a control unit for determining an optimal magnitude of said assistant force on the basis of both of said steering wheel angle indicating signal and said calculated vehicle speed representing value; and said means for deriving said calculated vehicle speed representing value, including means for setting said predetermined velocity gradient to a first positive velocity gradient when said speed difference exceeds said predetermined range at an expiration of said predetermined time interval and said anti-skid brake control system is deactive, to a second positive velocity gradient when said speed difference exceeds said predetermined range at an expiration of said predetermined time interval and said anti-skid brake control system is active, and to a negative velocity gradient when said speed difference is less than said predetermined range at an expiration of said predetermined time interval, so as to decrease said speed difference. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification