Vehicle guidance systems

Claim 1

A magnetic sensing head arrangement for indicating lateral deviation of the sensing head from desired paths in relation to a plurality of substantially parallel energized wires comprising first and second magnetic detectors horizontally spaced from one another in a lateral direction and disposed with their magnetic axes substantially vertical, a third magnetic detector disposed with its magnetic axis substantially vertical and located in the vicinity of the first and second detectors, the outputs from the first and second detectors being connected in phase-opposition when the direction of the axial component of the magnetic field is the same in both the first and second detectors to produce a resultant output dependent on the algebraic sum of the voltages induced in the first and second detectors, a phase sensitive detector to which the resultant output from the first and second detectors and the output of the third detector are connected via a switching device capable of feeding either the resultant output as a reference input to the phase sensitive detector and the output of the third detector as a signal input to the phase sensitive detector, or of feeding the resultant output as a signal input to the phase sensitive detector and the output of the third detector as a reference input to the phase sensitive detector, whereby the phase sensitiVe detector will give an output indicative of lateral deviations of the sensing head from a vertical plane containing the line of an energized wire or from a vertical plane midway between two energized wires respectively.

Claim 9

A method of guiding a vehicle under the control of a plurality of substantially parallel energized wires, wherein the vehicle may be guided to follow the path of a guide wire or to follow a path midway between adjacent guide wires by reversing connections to a signal input and a reference input of a phase sensitive detector so that, in the one case, the output of a single detector is applied as a signal input to the phase sensitive detector and a difference output between a separate pair of detector is applied as a reference input to the phase sensitive detector, and, in the other case, the difference signal from the pair of detectors is applied as a signal input to the phase sensitive detector and the output of a separate single detector is applied as a reference input to the phase sensitive detector being utilized to guide the vehicle in the desired path.

Claim 10

A method of guiding a vehicle under the control of a plurality of substantially parallel energized wires, wherein the vehicle may be guided to follow the path of a guide wire or to follow a path midway between adjacent guide wires by reversing connections to a signal input and a reference input of a phase sensitive detector so that, in the one case, the output of a single detector is applied as a signal input to the phase sensitive detector and a difference output between a separate pair of detector is applied as a reference input to the phase sensitive detector, and, in the other case, the difference signal from the pair of detectors is applied as a signal input to the phase sensitive detector and the output of a separate single detector is applied as a reference input to the phase sensitive detector being utilized to guide the vehicle in the desired path.