Vehicle guidance and control systems and methods for controllably guiding a vehicle along a predetermined pathway

A method of controlling a vehicle comprising the steps of:

• (a) providing a varying current in each of two spaced apart conductors disposed along an approximate path of travel desired for the vehicle, the current in the two spaced apart conductors alternating between a first state wherein the current in the first of the two spaced apart conductors is controlled to approximately represent one half cycle of a current sine wave as the current in a second of the two spaced apart conductors is kept substantially constant, and a second state wherein the current in the second of the two spaced apart conductors is controlled to approximately represent the other half cycle of the same current sine waves as the current in the first of the two spaced apart conductors is kept substantially constant;
• (b) varying the period of the current sine wave responsive to a separately controlled steering signal;
• (c) sensing by at least one sensing coil on the vehicle to be controlled, a varying magnetic field caused by the varying current in each of the two spaced apart conductors;
• (d) steering the vehicle responsive to an amplitude of the varying magnetic field caused by the varying current in one of the two spaced apart conductors relative to a n amplitude of the varying magnetic field caused by the varying current in the other of the two spaced apart conductors and the varying period of the current sine wave as sensed by the at least one sensing coil;
• whereby the path of travel of the vehicle relative to the two spaced apart conductors may be controlled by the separately controlled steering signal.