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An apparatus for use in turning steerable vehicle wheels upon manual rotation of a hand wheel includes a torque sensor connected with a torque sensor and a rear steering gear. The controller selectively controls the rear steering gear in response to an output from the torque sensor upon manual appli

An apparatus for use in turning steerable vehicle wheels upon manual rotation of a hand wheel includes a torque sensor connected with a torque sensor and a rear steering gear. The controller selectively controls the rear steering gear in response to an output from the torque sensor upon manual application of at least a predetermined torque to the hand wheel. The controller selectively controls the rear steering gear in response to the output from the torque sensor through a first range of turning movement of the front wheels so that the steering angle of the rear wheels has a first relationship to the steering angle of the front wheels and through a second range of turning movement of the front wheels so that the steering angle of the rear wheels has a second relationship different from the first relationship.

대표청구항 ▼

1. An apparatus for use in turning steerable wheels of a vehicle upon manual rotation of a hand wheel, said apparatus comprising: a front steering gear connected with front steerable wheels of the vehicle, said front steering gear being operable to turn the front steerable wheels of the vehicle upon

1. An apparatus for use in turning steerable wheels of a vehicle upon manual rotation of a hand wheel, said apparatus comprising: a front steering gear connected with front steerable wheels of the vehicle, said front steering gear being operable to turn the front steerable wheels of the vehicle upon manual rotation of the hand wheel;a rear steering gear connected with rear steerable wheels of the vehicle, said rear steering gear being operable to turn the rear steerable wheels upon manual rotation of the hand wheel;a sensor for sensing a parameter related to the steering of said front steerable wheels; anda controller which is operatively connected with said sensor and said rear steering gear, said controller being operable in response to the sensed parameter to effect operation of said rear steering gear to maintain a predetermined kinematic relationship between the front steerable wheels and the rear steerable wheels throughout a first range of turning movement of the front steerable wheels. the kinematic relationship being such that the front steerable wheels have a first angular relationship with the rear steerable wheels that remains the same throughout the first range of turning movement of the front steerable wheels,said controller being operable to effect of operation of said rear steering gear to oversteer the rear steerable wheels in response to an output from said sensor corresponding to at least a predetermined torque applied to the hand wheel which occurs when turning of the front steerable wheels during a second range of movement near a mechanical end of their range of turning movement. 2. The apparatus as set forth in claim 1, wherein said sensor senses at least one of a maignitude, rate, and acceleration of rotation of said hand wheel to determine the torque applied to said hand wheel. 3. The apparatus as set forth in claim 2, wherein said controller is operable to effect operation of said rear steering gear to oversteer the rear steerable wheels in response to an output from said sensor corresponding to at least a predetermined torque applied to the hand wheel which occurs when turning of the front steerable wheels during a second range of movement near a mechanical end of their range of turning movement. 4. The apparatus as set forth in claim 2, wherein said controller includes a lookup table that includes values of the torque applied to the hand wheel based on the hand wheel angle, said controller being operable to effect operation of said rear steering gear to oversteer the rear steerable wheels when the position of the hand wheel and the torque applied to the hand wheel correspond to a hand wheel position and operator torque stored in the look up table indicative of when turning of the front steerable wheels during a second range of movement approaching a mechanical end of their range of turning movement. 5. The apparatus as set forth in claim 2 including a motor operatively connected to said hand wheel and said controller, said controller being operable to effect operation of said motor to control the operator torque applied to the hand wheel, the operator torque being determined by said controller. 6. The apparatus as set forth in claim 5, wherein the operator torque is based on at least one signal indicative of a condition of the vehicle during a steering maneuver, said at least one signal being provided to said controller. 7. The apparatus as set forth in claim 5, wherein said controller is operable to effect operation of said rear steering gear to oversteer the rear steerable wheels in response to the output from said torque sensor corresponding to at least the torque which occurs when turning of the front steerable wheels during a second range of turning movement approaching a mechanical end of their range of turning movement. 8. The apparatus as set forth in claim 1, wherein the vehicle includes middle wheels located between said front and rear steerable wheels, each of said front, rear and middle wheels having a rolling axis, the predetermined kinematic relationship between said front and rear steerable wheels is such that all of the rolling axes for the wheels intersect each other at a common point throughout the first range of turning movement of the front steerable wheels. 9. The apparatus as set forth in claim 8, wherein said controller is operable to effect operation of said rear steering gear to oversteer the rear steerable wheels so that the angle between the rolling axis of one of the front steerable wheels and the rolling axis of one of the rear steerable wheels exceeds the predetermined angle in response to the output from said sensor corresponding to at least the torque which occurs when turning of the front steerable wheels during a second range of turning movement approaching a mechanical end of their range of turning movement. 10. The apparatus as set forth in claim 1, wherein the kinematic relationship is such that the turning angle of the rear steerable wheels is determined by a rotational magnitude of the hand wheel and an operator torque applied to the hand wheel. 11. An apparatus for use in turning steerable wheels of a vehicle upon manual rotation of a hand wheel, said apparatus Comprising: a front steering gear connected with front steerable wheels of the vehicle, said front steering gear being operable to turn the front steerable wheels of the vehicle upon manual rotation of the hand wheel;a rear steering gear connected with rear steerable wheels of the vehicle, said rear steering gear being operable to turn the rear steerable wheels upon manual rotation of the hand wheel;a sensor for sensing a parameter related to the steering of said front steerable wheels; anda controller which is operatively connected with said sensor and said rear steering gear, said controller being operable in response to the sensed parameter to effect operation of said rear steering gear to maintain a predetermined kinematic relationship between the front steerable wheels and the rear steerable wheels throughout a first range of turning movement of the front steerable wheels,wherein the kinematic relationship has the following equation: RA=K1HA+K2HT, where RA=turning angle of the rear steerable wheels, HA=rotational magnitude of the hand wheel, HT=operator torque applied to the hand wheel, and K1 and K2 are constant values. 12. An apparatus for use in turning steerable vehicle wheels upon manual rotation of a hand wheel, said apparatus comprising: a front steering gear connected with steerable front wheels of the vehicle, said front steering gear being operable to turn the steerable front wheels of the vehicle upon manual rotation of the hand wheel;a rear steering gear connected with steerable rear wheels of the vehicle;a torque sensor connected with the hand wheel; anda controller which is connected with said torque sensor and rear steering gear, said controller selectively controlling said rear steering gear in response to an output from said torque sensor upon manual application of at least a predetermined torque to the hand wheel, said torque sensor having an output which corresponds to a torque which is less than the predetermined torque throughout turning of the steerable front wheels through a first range of turning movement, said torque sensor having an output which corresponds to a torque which is at least as great as the predetermined torque which occurs when turning of the steerable front wheels during a second range of turning movement of the front steerable wheels, said controller selectively controlling said rear steering gear in response to the output from said torque sensor through the first range of turning movement of the said front steerable wheels so that that steering angle of the rear steerable wheels has a first relationship to the steering angle of the front steerable wheels, said controller selectively controlling said rear steering gear in response to the output from said torque sensor through the second range of turning movement of said front steerable wheels so that the steering angle of the rear steerable wheels has a second relationship to the steering angle of the front steerable wheels different from the first relationship. 13. An apparatus as set forth in claim 12 wherein said controller is operable to effect operation of said rear steering gear through the first range of turning movement of said front steerable wheels so that the first relationship of the steering angle of the rear steerable wheels is a kinematic relationship with the steering angle of the front steerable wheels. 14. An apparatus as set forth in claim 13 wherein said controller is operable to effect operation of said rear steering gear through the second range of turning movement of the said front steerable wheels so that the second relationship of the steering angle of the rear steerable wheels is an oversteering relationship with the steering angle of the front steerable wheels. 15. An apparatus as set forth in claim 12 wherein the torque sensor has an output which is less than the predetermined torque throughout turning of the steerable front wheels through the first range of turning movement during normal operation of the front steering gear, said torque sensor having an output which corresponds to a torque which is at least as great as the predetermined torque which occurs when turning of the steerable front wheels through the second range of motion in a direction that cannot be performed, the controller being operable to effect operation of the rear steering gear in response to the output from the torque sensor corresponding to at least the torque which occurs when turning of the steerable front wheels in the direction that cannot be performed. 16. An apparatus as set forth in claim 12, wherein the controller, in response to the output from the torque sensor, effects rotation of the hand wheel to adjust a steering feel of the hand wheel, the controller selectively controlling the rear steering gear in response to the adjusted steering feel of the hand wheel so that the rear steerable wheel have the first relationship to the steering angle of the front steerable wheels through the first range of turning movement of the front steerable wheels and so that the rear steerable wheels have the second relationship to the steering angle of the front steerable wheels through the second range of turning movement of the front steerable wheels.