| 摘要 |
A pathway-based method, apparatus and system for tracking, sensing and communicating with an object, such as a carriage or vehicle moving on a pathway. The system includes a transmitter winding along the pathway that is energized by a transmitter and one or more sensing windings in which a signal is induced. The vehicle contains a transducer that creates a position-indicating coupling of the transmitted signal into the sensing windings. The transducer may be a passive ferromagnetic or conductive body that locally alters coupling between the windings, or a tuned coil carried on the vehicle that couples energy received from the transmitter into a sensing winding. Absolute position may be established at regular intervals using a discrete position sensor, such as a Hall Effect magnetic field sensor, and, the signal derived from the sensing windings can be monitored, by counting cycles or determining phase, to determine a precise vehicle position. With one sensing winding it is possible to determine distance to about 1/8 of a wavelength and by using two or more phased sensing windings a wayside controller determines the position within a wavelength to a smaller fraction of a wavelength. The position sensing can be accomplished without any source of power on the vehicle, and may extract power from the transducer or position sensing system to drive an electronic communication unit on the vehicle. Modulation of the position sense signal can be used to provide two-way communication between the vehicle and the wayside controller. A typical application is to transmit a vehicle identification number to a controller, or for the controller to activate a mechanism on the vehicle. |
