TWO-WAY COMMUNICATION SYSTEM FOR TRACKING LOCATIONS AND STATUSES OF WHEELED VEHICLES

A vehicle tracking system includes a wheel (32) containing sensor circuitry (88, 90, 92, 94, 96) capable of sensing various types of conditions, such as wheel rotation, wheel vibration caused by skidding, and specific electromagnetic and/or magnetic signals indicative of particular wheel locations. The sensor circuitry is coupled to an RF transceiver (82), which may but need not be included within the wheel. The wheel (32) may also include a brake mechanism (100). In one embodiment, the wheels (32) are placed on shopping carts (30) and are used to collect and monitor shopping cart status and location data via a wireless network. The collected data may be used for various purposes, such as locking the wheel of an exiting cart if the customer has not paid, estimating numbers of queued carts, stopping wheel skid events that occur during mechanized cart retrieval, store planning, and providing location-based messaging to customers.