A vehicle tracking system includes a wheel assembly containing sensor circuitry capable of sensing one or more 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 wheel assembly may also include a brake mechanism. The wheel assemblies may be mounted on shopping carts and used to collect and monitor shopping cart status and location data via a wireless network. In one embodiment, the wheel assembly communicates via a wired or wireless connection with a handlebar mounted display unit of the cart.

RFID devices are provided for improving the performance of electronic surveillance article systems. The RFID devices may be modified in any of a number of ways to decrease their peak sensitivity and increase their bandwidth, thereby stabilizing their read range. The performance of an RFID device will depend on the nature of the article to which it is associated, such that the nature of the article to which the RFID device is to be associated may be factored into the design of the RFID device to equalize the performance at an operating frequency of RFID devices associated with different articles. By reducing the peak sensitivity and increasing the bandwidth of RFID devices in an electronic article surveillance system, the size of a transition zone between two read zones of the system may be reduced.

A navigation system uses a dead reckoning method to estimate an object's present position relative to one or more prior positions. In some embodiments, the dead reckoning method determines a change in position from the object's heading and speed during an elapsed time interval. In embodiments suitable for use with wheeled objects, the dead reckoning method determines the change in position by measuring the heading and the amount of wheel rotation. Some or all of the components of the navigation system may be disposed within a wheel, such as a wheel of a shopping cart.

A vehicle tracking system includes a wheel assembly containing sensor circuitry capable of sensing various types of conditions, such as specific electromagnetic and/or magnetic signals indicative of particular wheel locations. The sensor circuitry is coupled to an RF transceiver, which may but need not be included within the wheel. The wheel may also include a brake mechanism. In one embodiment, the wheels are placed on shopping carts and are used to collect and monitor shopping cart status and location data via a wireless network. In some embodiments, the wheel assemblies detect that they have entered into particular zones by measuring received signal strengths of received command transmissions, and by comparing these measurements to thresholds that are used to define zone boundaries.

A system is disclosed for tracking and controlling shopping carts and other types of human propelled vehicles. The system includes a wheel assembly that attaches to a cart. The wheel assembly includes a brake unit for inhibiting cart motion, and includes wireless communication circuitry. The wheel assembly is capable of activating the brake unit in response to one or more conditions, such as the receipt of an RF signal or command. In some embodiments, the system also includes a display unit that displays information to a user of the cart, including information regarding the cart's proximity to a lock zone in which the brake unit will become activated.

A vehicle tracking system includes a wheel containing sensor circuitry 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, which may but need not be included within the wheel. The wheel may also include a brake mechanism. In one embodiment, the wheels are placed on shopping carts 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.

Various systems for detecting unauthorized exit events are disclosed. The systems can support a variety of different methods for assessing whether a customer is exiting the store without paying. The particular method or methods used may vary widely based on the types and the locations of the system components included in a given installation. For example, the system may be configured to detect that a cart has passed or is passing through a checkout lane.

A navigation system uses a dead reckoning method to estimate an object's present position relative to one or more prior positions. In some embodiments, the dead reckoning method determines a change in position from the object's heading and speed during an elapsed time interval. In embodiments suitable for use with wheeled objects, the dead reckoning method determines the change in position by measuring the heading and the amount of wheel rotation. Some or all of the components of the navigation system may be disposed within a wheel, such as a wheel of a shopping cart.

An EAS system employs multiple antennas which are in separate electrical circuits and do not overlap to avoid magnetic coupling. Each antenna is paired with each other antenna. The controls for the system employ multi-function amplifier filters (MAF) to perform a difference operation on the signals in each pair. The results are converted from analog to digital and directed to a digital signal processor (DSP). The DSP adjusts digital potentiometers to minimize the differences at the MAFs. The controls then operate at least one antenna to pulse generate an interrogation field. The controls monitor the antenna signals for additional signal at the MAFs. The DSP performs pattern recognition on additional signals at the MAFs to distinguish types of EAS tags.

A power generation system for wheeled objects comprises a generator mechanically coupled to one or more of the object's wheels to convert wheel rotational energy into electrical energy. The power generation system may comprise an electrical storage device configured to store the electrical power produced by the generator. Power from the generator and/or the electrical storage device can be used to provide power to other electrical systems in or on the object. In certain embodiments, the electrical storage device comprises a bank of high-capacity capacitors connected in series. Some embodiments use a control circuit, for example, to regulate the charging and discharging of the capacitor bank and to provide suitable voltages for other systems. The power generation system may be disposed within an object's wheel, such as a wheel of a shopping cart.