US 4,307,329 A · Wire guidance method and apparatus

Abstract

A ground vehicle guidance system for following a current-carrying guidewire provides improved steering stability over a wide range of speeds and improved immunity to inductive field anomalies by computing vehicle heading and lateral displacement using sensor signals themselves substantially insensitive to heading variations, with the sensor signals being processed to provide steering command signals having specified relationships to vehicle steering geometry, so that desired damping factors can be obtained for both forward and reverse travel. Improved vehicle speed-limiting and stopping circuits control truck operation in accordance with computed heading and lateral displacement deviations independently from each other. Steering systems are illustrated both for vehicles using steerable wheels and vehicles steered by differential drive wheel speed control.

Claims24

Dependent claims

Automatic guidance apparatus for a ground vehicle operable in forward and reverse directions along a reference path defined by a current-carrying guidewire, comprising, in combination:

a sensor assembly operative during both forward and reverse directions of travel to provide a first signal which varies in proportion to the lateral displacement of a first point on said vehicle from said reference path and to provide a second signal which varies in proportion to the heading deviation of a first axis of said vehicle from said reference path;
means for combining said first and second signals using predetermined scale factors to provide a command signal during both forward and reverse directions of travel including means for reversing the sense of said second signal between forward and reverse directions of travel, said vehicle including steering means responsive to said command signal for steering said vehicle.

A guided ground vehicle, comprising, in combination:

sensor means operative to provide a first signal commensurate with lateral displacement of a point on said sensor means from a reference path defined by a current-carrying guidewire and a second signal commensurate with heading deviation of said sensor means from said reference path;
means for combining said first and second signals to provide a steering command signal;
a steerable wheel for steering said vehicle;
a closed-loop position servomechanism connected to receive said steering command signal and to position said steerable wheel;
switching means for varying between first and second values the amount which said servomechanism turns said steerable wheel per unit magnitude of said command signal;
and comparator means responsive to said first and second signals and operative when both said first and second signals decrease below respective predetermined values for operating said switching means to decrease said amount to said second value.

3 more elements

A sensor assembly for use on a guided ground vehicle having traction motor means for driving said vehicle, a steerable wheel for steering said vehicle, and a servomechanism connected to position said steerable wheel, comprising, in combination:

a sensor having a plurality of coils affixed to said vehicle and operable to provide first and second voltages commensurate with displacements of said coils from a reference path defined by a current-carrying guidewire, means for combining said first and second voltages to provide a first signal commensurate with lateral displacement of said sensor from said reference path and to provide a second signal commensurate with heading deviation of said sensor from said reference path, means for combining said first and second signals to provide a steering command signal, said servomechanism being responsive to said steering command signal;
and comparator means responsive to said first and second signals for controlling said traction motor means, said comparator means being operable to limit speed of said vehicle without stopping said vehicle while either said first signal or said second signal exceeds a respective first predetermined value.

Dependencies are inferred from the claim text.

Wire guidance method and apparatus

Life of this patent

Wire guidance method and apparatus

Life of this patent

Abstract

Claims24