Citation

Spangler RA, Snell FM. Highw. Res. Board bull. 1962; 338: 20-27.

Copyright

(Copyright © 1962, National Research Council (U.S.A.), Highway Research Board)

DOI

unavailable

PMID

unavailable

Abstract

A new vehicle guidance and speed control system, using only passive roadbed equipment, is presented. The operation of the system is based on the detection of position and speed information by means of radio-frequency magnetic fields induced in roadbed loops by a vehicle-borne generator. By suitable coupling of the guidance detector to the vehicle steering mechanism, the guidance system is made null-seeking, thus eliminating any dependence on the absolute magnitude of the signal seen by the detector. The operation of the speed control system depends on a pulse frequency derived from the spacing of the roadbed loops. The system is shown to possess a number of advantages, including (1) passive, durable, and inexpensive road equipment, (2) individual vehicular-borne active equipment, presenting no standing wave problem and involving low power levels, (3) detection equipment entirely phase dependent, rather than amplitude dependent, (4) inherent damping of lateral acceleration, (5) speed control easily subject to external moderation, and (6) the system lending itself to adequate safety features and to adaptions and additions necessary for future extended control functions, including completely programmed travel.