Abstract: A multiple-axle steering system for an agricultural machine with at least one primary-controlled axle and at least one secondary axle, where the latter's steering deflection angle varies along a progressive characteristic curve as a function of the primary-controlled axle's steering deflection angle. The variation in steering deflection angle along the progressive characteristic curve means that the steering deflection angle of the primary-controlled axle in a range around the zero or neutral position initially results in only a slight steering deflection of the secondary axle. As the steering deflection of the primary-controlled axle increases, the steering deflection angle of the secondary axle progressively approaches the steering deflection angle of the primary-controlled axle. When using all-wheel steering, the use of the progressive characteristic curve facilitates smooth steering when driving on the road, where usually minimal steering deflection is performed by the machine operator.

Abstract: A system for controlling steering of a vehicle, including a steering unit having an electric motor which steers driven wheels of the vehicle, a first steering control unit (EPS ECU 76) for controlling the actuator, a CCD camera for detecting a condition of a lane on a road on which the vehicle travels, a steering assist torque determining unit for determining a steering assist torque necessary for holding a positional relationship between the vehicle and the lane condition, a torque sensor for detecting a steering torque manually applied to the steering unit by the driver, second steering control unit for calculating a torque command to be output to the first steering control unit based on the steering assist torque calculated by the steering assist torque calculating unit and the detected steering torque to control the motor such that the torque command decreases.

Abstract: In a method for controlling a rear wheel steering device of a front and rear wheel steering vehicle, the target computed rear wheel steering angle is defined as a value smaller than the normal computed target rear wheel steering angle when the load of the steering actuator is greater than a prescribed threshold value, and which is otherwise equal to the normal computed target rear wheel steering angle, and the steering actuator is actuated according to a deviation of the actual rear wheel steering angle from the modified computed target rear wheel steering angle, typically with a duty ratio control. Thus, the rear wheel steering device can be operated in a satisfactory manner even when the output capacity of the actuator for the rear wheel steering device is limited, and the steering load is high. A high load condition typically occurs when the vehicle is stationary and when the steering wheel is turned sharply while the vehicle is traveling over a road surface having a high frictional coefficient.

Abstract: A steering system for a multiple-axle vehicle includes a front axle steering arrangement steering at least one pair of front wheels connected to at least one front axle, a middle axle steering arrangement steering at least one pair of middle wheels connected to at least one middle axle, and a first connector operationally connecting the middle axle steering arrangement to the front axle steering arrangement. A rear axle steering arrangement steers at least one pair of rear wheels connected to at least one rear axle, and an adjustable connector adjustably connects the middle axle steering arrangement to the rear axle steering arrangement. A controller controls the middle axle steering arrangement based on sensor output indicative of a ratio of a steering deflection angle of the front wheels to a steering deflection angle of the rear wheels.

Abstract: A drive system for utility vehicles, in particular for agricultural or industrial tractors, includes a generator driven by an internal combustion engine, a drive axle with wheels driven by associated electric motors which are powered by the generator, a steerable axle with wheels which are steerable together or individually by steering actuators, and manual operating control devices for vehicle operating functions such as steering and vehicle. The drive system includes a process computer which includes parallel and independently operating function modules for controlling high priority vehicle functions, such as steering, as well as function modules for low priority vehicle functions, such as speed input. The process computer transmits target value signals for actuator, such as electric wheel drive motors and steering actuators, in the form of a combined message communicated over a system bus. Information is exchanged between the function modules internally within the processor.

Abstract: A tractor (1) has front wheels (2), rear wheels (3) and carries an implement (7, 10) by a linkage (8) or tows a trailer (11). The front wheels (2) are steered normally by a steering wheel (6). The rear wheels (3) can be held in fixed alignment or they can be steered in various selectable modes, being slaved to the front wheels. In one mode, they are turned in the opposite direction to the front wheels, to give a very tight turning circle. In another mode, they turn with the front wheels but to a lesser degree, governed by the tractor wheel base (A) and the distance (B) of this implement behind the tractor, to keep lateral forces on the implement to a minimum. There can be automatic changeover between modes of steering.

Abstract: Disclosed is an automatic traveling control system for a vehicle which can provide satisfactory steering control during automatic traveling regardless of vehicle speeds. Wheel speeds of rear left and right wheels detected by first and second wheel speed sensors, and image data detected by a camera and including a guide way are input to a controller. The controller controls an amount of steering of a steering system by a drive motor to perform steering control through one of first and second control means which are switched over depending on a vehicle speed, thereby realizing autonomous traveling in which a predetermined positional relationship is held between the guide way and the vehicle.

Abstract: Disclosed is a rear wheel neutralizing system for a four-wheel steering vehicle, including an actuator for returning rear wheels to their neutral positions; a potentiometer for detecting a returning displacement to the neutral position of the wheel; a motor for operating the actuator; a vehicle speed sensor for detecting vehicle speeds; and an electronic control unit for determining whether the four-wheel steering system is malfunctioning and for operating the motor while receiving a signal from the vehicle speed sensor. The rear wheel neutralizing system further comprises an encoder for detecting the angular velocity of the motor and transmitting a signal on the angular velocity to the electronic control unit.

Abstract: A vehicle attitude control device including a yaw moment control mechanism for giving a yaw moment to the vehicle and controlling the yaw moment, and a controller for controlling the yaw moment control mechanism in a normal target follow-up control mode so that the actual yaw rate detected by a yaw rate sensor coincides with a target value determined on the basis of an angle of rotation of a steering wheel detected by a steering wheel angle sensor, and wherein a yaw moment reducing device is provided for reducing the yaw moment to be given to the vehicle by the yaw moment control mechanism, to a reduced value smaller than a normal value to which the yaw moment is controlled in the normal target follow-up control mode.

Abstract: A rear wheel steer control method and apparatus for a four wheel steer vehicle executes an opposite phase steer control on the basis of detected values of a front wheel steer angle sensor and a vehicle speed sensor during a low vehicle speed. The opposite phase steering is stopped for a predetermined distance from a start of straight running, then the rear wheel steer angle is controlled by a primary delay control. When the front wheel steer angle is decreased, the primary delay control is stopped in a predetermined condition. Therefore, the four wheel steer vehicle gives a smooth steer feeling to a driver in every driven condition.

Abstract: A movement state control apparatus for a wheeled vehicle capable of constantly maintaining the movement state of the vehicle in an optimal condition even if various kinds of parameters of the vehicle are changed. The control apparatus includes a yaw rate sensor for detecting a yaw rate as one of movement state variables of the vehicle, a microcomputer programmed to detect a lateral slip angle as one of the other movement state variables for determining a target yaw rate and a target lateral slip angle as a target movement state variable and to calculate a feedback rear wheel steering angle by multiplying a difference between the detected movement state variable and the target movement state variable with a feedback gain of a predetermined frequency characteristic for ensuring robust stability of the vehicle and robust control performance without any influences caused by a zero-point drift and high frequency noises of the yaw sensor.

Abstract: A movement state estimation method wherein a state equation of an observer is converted into a discrete equation by bilinear transformation and successively calculated to estimate unobserved movement state variables on a basis of observable movement state variables applied as a reference input.

Abstract: A method and apparatus are provided for improving vehicle steering in unfamiliar safety critical situations by controlling power steering assist in response to the slip angle of the vehicle and the steering rate of the vehicle. When a vehicle is in a slide or a slide is imminent, the steering wheel should be turned in the direction of the slide to stabilize the vehicle and take the vehicle out of the slide or possibility of a slide. Accordingly, a positive supplemental steering assist is provided for the steering system if the driver is turning the steering wheel in the direction to correct the slide. If, on the other hand, the driver is turning the steering wheel in the direction which will increase the slide, a negative supplemental assist is provided for the steering system.

Abstract: A four wheel steering strategy determines when the rear tire longitudinal slip becomes greater than the front tire longitudinal slip, either due to braking or acceleration, such that the rear tire slip angles must be increased to maintain vehicle balance with respect to the level of understeer/oversteer. The out-of-phase rear steering angle is reduced or the in-phase rear steering angle is increased to increase the rear tire slip angles and thereby correct vehicle balance. Three embodiments are disclosed which use estimated tire longitudinal slips, wheel speeds, and engine throttle information, respectively. The required inputs for the various embodiments can be obtained from independent sensors or preferably are available from other vehicle systems such as an anti-lock braking system, a traction control system or an engine management system. Advantageously, the present invention operates without requiring expensive sensors such as yaw sensors which are currently not feasible for mass market use.

Abstract: A steering angle control apparatus for controlling steering angles of front wheels and rear wheels of a vehicle includes a yaw rate detector for detecting an actual yaw rate of the vehicle. A desired yaw rate calculator estimates a desired yaw rate for causing the vehicle to drive stably. A yaw rate disturbance calculator calculates a yaw rate disturbance which causes the detected yaw rate to deviate from an ideal yaw rate of the vehicle assuming driving in ideal driving conditions. A desired yaw rate compensator compensates the desired yaw rate based on the calculated yaw rate disturbance and produces a compensated yaw rate so that the desired yaw rate tracks the compensated yaw rate.

Abstract: In a method for controlling a front and rear wheel steering system in which front wheels of a vehicle are steered according to a combination of a steering wheel input and an output from a compensatory front wheel steering actuator, and rear wheels of the vehicle are steered by a rear wheel steering actuator. The front wheel steering angle is augmented according to the deviation of the actual yaw rate from a target yaw rate computed from the travelling speed of the vehicle and the steering input from the steering wheel to compensate for the delay in the yaw rate response so that the rear end of the vehicle would not be swung sideways during a turning maneuver, and the vehicle operator would not be subjected to any unfamiliar feeling.

Abstract: In a steering angle control system including a feed-forward control for producing a desired vehicle motion variable and a feedback control for suppressing disturbances, a controller calculates a corrected steering angle from a detected steering angle and a premeasured characteristic of a steering system. The desired vehicle motion variable is calculated from a vehicle speed and the corrected steering angle. The feedback control is executed according to the difference between the desired and detected vehicle motion variables. Therefore, a driver can control a vehicle with a smooth control response in spite of a non-linear characteristic of the steering system.

Abstract: An auxiliary steering angle control system for a vehicle comprises a vehicle condition detecting section for detecting a vehicle condition, a desired motion variable calculating section for calculating a desired value of the motion variable actually generated to the vehicle from the detected vehicle condition, an actual motion variable detecting section for detecting an actual motion variable actually generated in the vehicle, an auxiliary steering angle feedback control-input determining section for determining an auxiliary steering feedback control-input according to the difference between the desired motion variable and the detected actual-vehicle motion variable, a road condition detecting section for detecting a road variable indicative of a condition of a road on which the vehicle is traveling, and an auxiliary steering feedback control-input correcting section for reducing the auxiliary steering angle feedback control-input when the road condition detecting section outputs a signal indicative that the

Abstract: A vehicular brake booster using fluid pressurized by a hydraulic power steering system hydraulic pump. Fluid pressure is controlled by using a pressure regulator in the pump output and by electronically switching fixed orifices in a boost developing valve controlling fluid flow within the power steering system. Additional control is effected by electronically opening and closing apply and relief valves controlling fluid flow respectively to and from a brake power booster for differing periods.

Abstract: A vehicle has a steering control system including a first mode in which the front and rear steering mechanisms operate and a second mode in which only the front steering mechanism operates. When the control system is switched from the first mode to the second mode by a master switch, the change to the second mode is prevented unless and until the rear steering mechanism is in a straight-ahead condition. This condition is sensed by an alignment sensor which is activated by the switching of the master switch to the state corresponding to the second mode.

Abstract: The present invention relates a rear wheel self-steering system for a vehicle which can minimize a turning radius of a vehicle and a tire wear by independently steering the rear wheel during cornering. The system includes a side frame, a first spring mounted on a first rear wheel axle below the side frame and having a front end fixed to the side frame, a second spring mounted on a second rear wheel axle below the side frame and having a rear end fixed to the side frame, and a steering control part for controlling a distance between the first and second rear wheel axles in accordance with a vehicle's running state such that when the vehicle is in cornering the first rear wheel axle becomes far away from the second rear wheel axle, the steering system connecting the first and second spring members to each other.