Steering system and method for train of wheeled vehicles

A method of steering a train of at least three vehicles connected together, said method comprising:

• providing a train of at least three vehicles comprising first and second end vehicles and at least one intermediate vehicle, each vehicle having at least one pair of propelling devices mounted thereon and supporting the vehicle, each propelling device including a steerable wheel pivotable about a substantially vertical axis in order to steer the vehicle, the propelling devices of each pair being mounted on opposite sides of the respective vehicle, each vehicle further including power steering mechanism for pivoting the wheels of the or each pair about their respective vertical axes and a controller for operating said power steering means in order to steer said train, adjacent vehicles of the train being pivotally connected to each other for pivotal movement about a substantially vertical vehicle pivot axis;
• causing said train to move over ground in a desired direction towards one of said end vehicles;
• steering a leading pair of the wheels on said one end vehicle to a desired steering angle;
• sensing said desired steering angle on a continual or frequent periodic basis and providing first signals indicative thereof to said controller;
• storing a series of said desired steering angles as the train is moved over the ground;
• sensing on a continual or frequent periodic basis the current steering angle for each pair of wheels trailing said leading pair of wheels relative to the direction of travel of said train;
• providing an indication of the distance traveled by said train from a selected location to said controller;
• providing controller readable indications of intercar angles between pairs of adjacent vehicles to said controller, each intercar angle being defined by central longitudinal axes of a respective pair of the vehicles and said vehicle pivot axis for the respective pair, and
• calculating steering angle corrections for trailing pairs of said wheels by means of said controller as the train is moving, said steering angle corrections being a function of the following:
• (i) the distance traveled by said train of vehicles;
• (ii) the stored desired steering angles of the leading pair of wheels, the controller selecting a stored steering angle for each trailing pair that represents the desired steering angle when said leading pair of wheels was at about the same location where the respective trailing pair is currently located;
• (iii) the current intercar angle associated with the respective trailing pair, this associated intercar angle having its defining vertical axis located between the respective trailing pair;
• and
• (iv) the current steering angle of each pair of wheels trailing said leading pair of wheels.

A steering system for at least three vehicles connected together to form a train, adjacent vehicles in said train being pivotally connected to each other for pivotable movement about a substantially vertical axis, each vehicle having a pair of steerable wheels mounted thereon and supporting the vehicle, the pairs of steerable wheels including a selected leading pair mounted on one of said vehicles located at one end of the train, said leading pair having its steering angle determined by an operator controlling a steering device for said leading pair during use of the steering system, each vehicle having an actuator mechanism for steering its respective pair of wheels which are mounted on opposite sides of the vehicle, the system comprising:

• an electrical controller system for automatically steering all of the pairs of wheels trailing behind said leading pair, said controller system including a memory unit for storing sensed data and an electrical indicator for providing a signal indicating the current distance traveled by the train from a predetermined location;
• vehicle angle sensors for measuring selected intercar angles between adjacent vehicles, generating first electrical signals indicative thereof, and transmitting such first electrical signals to said controller system, the intercar angle being an angle defined by central longitudinal axes of a respective pair of adjacent vehicles and said substantially vertical axis about which one of the respective pair can pivot relative to the other vehicle of the pair;
• a first wheel angle sensor for providing an electrical signal indicative of the current steering angle of said selected leading pair of wheels to said controller system, said memory unit being adapted to store a series of sensed steering angles for the selected leading pair, each of the stored steering angles corresponding to the steering angle of the leading pair at a series of locations along a path of travel of said train;
• additional wheel angle sensors for sensing actual steering angles of the said pairs of wheels trailing behind such leading pair and for providing electrical signals indicative thereof to said controller system;
• said controller system during use of said steering system adjusting the actual steering angle for each trailing pair of wheels to a desired steering angle, the controller system calculating an adjustment amount for each trailing pair on the basis of the following parameters:
• (i) the current distance traveled by said train;
• (ii) a respective one of the stored series of sensed steering angles, said controller choosing said respective one of the steering angles representing the steering angle of the leading pair of wheels when said leading pair was at approximately the current location of the respective trailing pair;
• and
• (iii) the current intercar angle associated with the respective trailing pair, this associated intercar angle having its defining vertical axis close to the respective trailing pair.