Abstract: A steering apparatus for a steerable vehicle includes a steering unit, an operating unit, a backup unit, and a control unit. The backup unit selectively connects/disconnects the steering unit and the operating unit. The control unit is operable in two control modes including an SBW mode and a PS mode. In the SBW mode, the control unit separates the steering unit from the operating unit; controls a steer angle of the vehicle in accordance with a manual steering effort; and switches the control mode from the SBW mode to the PS mode when an SBW-to-PS mode switch condition is satisfied, the SBW-to-PS mode switch condition including a condition that the steer angle is larger than or equal to a first threshold angle. In the PS mode, the control unit connects the steering unit and the operating unit; controls an assist steering effort to boost the manual steering effort.

Abstract: A vehicle steering apparatus includes a steering input section having at least a steering wheel to which steering input is applied, and a steering output section having at least a steering rack shaft and operatively associated with left and right steered wheels for steering the steered wheels by steering-rack-shaft movement produced by a steering force determined based on the steering input and transmitted directly or indirectly to the steering rack shaft. The steering rack shaft is split into left and right movable rack shaft portions. Also provided is a steer angle converter enabling a differential rack stroke between left and right rack strokes of the left and right movable rack shaft portions. The steer angle converter is constructed by at least one of a variable-pitch dual rack arrangement and a dual taper-pulley arrangement of a cable back-up mechanism.

Abstract: A fail-safe steering system for a vehicle, which prevents movable elements of a backup mechanism from being dragged by motions of an associated one of a steering input section and a steering output section under normal operating conditions of the system, is provided. The fail-safe steering system includes two selectively engageable clutch mechanisms operatively connectable between the steering input section and the backup mechanism and between the backup mechanism and the steering output section. The fail-safe steering system also includes a mechanism for keeping the backup mechanism in the neutral condition during backup mechanism being mechanically separated under normal operating conditions of the system.

Abstract: A vehicle steering system is provided with a primary steering system, a backup steering system and a control system that switches from the primary steering system to the backup steering system when a defect is determined in the primary steering system such as a defeat in a steering reaction force actuator. The vehicle steering system has a pair of clutches that mechanically disconnect the steering wheel from the steerable vehicle wheels in normal situations, and connect them when the steering reaction force actuator is determined to be defective. The control system has a steering malfunction detection section that detects a malfunction in the steering reaction force actuator, and a steering control limiting section that limits the control commands to the steering gear unit actuator from when the steering reaction force actuator is determined to be malfunctioning to when both the clutches are connected.

Abstract: In a multiplex power steering device for a wheeled vehicle, there is provided a control unit which includes a feedback computing part. The feedback computing part comprises an operating force estimating section that, by analyzing an output from a controlled system of actuators of a steering mechanism, estimates an output of the actuators, a disturbance estimating section that, by comparing a control signal actually fed to the actuators and the estimated output of the actuators, estimates a disturbance applied to the controlled system from the exterior, and a disturbance compensating section that adjusts the control signal in a manner to remove the estimated disturbance therefrom. The control unit calculates the control signal on the assumption that the actuators constitute a single actuator.

Abstract: A steering apparatus for a steerable vehicle includes a steering unit, an operating unit, a backup unit, and a control unit. The backup unit selectively connects/disconnects the steering unit and the operating unit. The control unit is operable in two control modes including an SBW mode and a PS mode. In the SBW mode, the control unit separates the steering unit from the operating unit; controls a steer angle of the vehicle in accordance with a manual steering effort; and switches the control mode from the SBW mode to the PS mode when an SBW-to-PS mode switch condition is satisfied, the SBW-to-PS mode switch condition including a condition that the steer angle is larger than or equal to a first threshold angle. In the PS mode, the control unit connects the steering unit and the operating unit; controls an assist steering effort to boost the manual steering effort.

Abstract: In steering apparatus and method for an automotive vehicle, a turning section that turns steered road wheels is provided, a clutch is installed in a predetermined position in a midway through a steering system from an operation input section to the steered road wheels to link between the operation input section and the steered road wheels, a steering angle of the operation portion is detected, a turning angle is detected, an elastically deformable member is interposed between the operation portion and the turning portion to transmit a steering torque inputted from the operation input section to the steered road wheels when the clutch causes the operation input portion and the steered road wheels to be connected; and an angular deviation between the steering angle detection value and the turning angle detection value developed due to a deformation of the member is calculated.

Abstract: A vehicle steering apparatus includes a steering input section having at least a steering wheel to which steering input is applied, and a steering output section having at least a steering rack shaft and operatively associated with left and right steered wheels for steering the steered wheels by steering-rack-shaft movement produced by a steering force determined based on the steering input and transmitted directly or indirectly to the steering rack shaft. The steering rack shaft is split into left and right movable rack shaft portions. Also provided is a steer angle converter enabling a differential rack stroke between left and right rack strokes of the left and right movable rack shaft portions. The steer angle converter is constructed by at least one of a variable-pitch dual rack arrangement and a dual taper-pulley arrangement of a cable back-up mechanism.

Abstract: A vehicle steering system is provided with a primary steering system, a backup steering system and a control system that switches from the primary steering system to the backup steering system when a defect is determined in the primary steering system such as a defeat in a steering reaction force actuator. The vehicle steering system has a pair of clutches that mechanically disconnect the steering wheel from the steerable vehicle wheels in normal situations, and connect them when the steering reaction force actuator is determined to be defective. The control system has a steering malfunction detection section that detects a malfunction in the steering reaction force actuator, and a steering control limiting section that limits the control commands to the steering gear unit actuator from when the steering reaction force actuator is determined to be malfunctioning to when both the clutches are connected.

Abstract: A fail-safe steering system for a vehicle, which prevents movable elements of a backup mechanism from being dragged by motions of an associated one of a steering input section and a steering output section under normal operating conditions of the system, is provided. The fail-safe steering system includes two selectively engageable clutch mechanisms operatively connectable between the steering input section and the backup mechanism and between the backup mechanism and the steering output section. The fail-safe steering system also includes a mechanism for keeping the backup mechanism in the neutral condition during backup mechanism being mechanically separated under normal operating conditions of the system.

Abstract: In steering apparatus and method for an automotive vehicle, a turning section that turns steered road wheels is provided, a clutch is installed in a predetermined position in a midway through a steering system from an operation input section to the steered road wheels to link between the operation input section and the steered road wheels, a steering angle of the operation portion is detected, a turning angle is detected, an elastically deformable member is interposed between the operation portion and the turning portion to transmit a steering torque inputted from the operation input section to the steered road wheels when the clutch causes the operation input portion and the steered road wheels to be connected; and an angular deviation between the steering angle detection value and the turning angle detection value developed due to a deformation of the member is calculated.

Abstract: In a multiplex power steering device for a wheeled vehicle, there is provided a control unit which includes a feedback computing part. The feedback computing part comprises an operating force estimating section that, by analyzing an output from a controlled system of actuators of a steering mechanism, estimates an output of the actuators, a disturbance estimating section that, by comparing a control signal actually fed to the actuators and the estimated output of the actuators, estimates a disturbance applied to the controlled system from the exterior, and a disturbance compensating section that adjusts the control signal in a manner to remove the estimated disturbance therefrom. The control unit calculates the control signal on the assumption that the actuators constitute a single actuator.