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.

A system for monitoring and controlling shopping cart usage comprises a wheel assembly that attaches to a shopping cart. In some embodiments the wheel assembly includes a wheel, a brake that can be activated to inhibit rotation of the wheel, a controller that controls the brake, a VLF receiver, and an RF transceiver. The RF transceiver may, for example, operate in a 2.4 GHz frequency band. In some implementations, the RF transceiver may be used to detect entry of the shopping cart into a checkout area of the store, and the VLF receiver may be used to detect that the shopping cart is exiting the store. The controller may activate the brake if the shopping cart attempts to exit the store without first passing through a checkout area.

In an embodiment, a method of managing an output power delivered by an antenna of a NFC apparatus includes: providing a matching circuit with a first tuning capacitive network coupled in series between a NFC controller and the antenna and with a second tuning capacitive network coupled to the NFC controller and the antenna and to a reference terminal, wherein the first or second tuning capacitive network has a variable capacitive value; determining tuning capacitive values of the first tuning capacitive networks to adjust a delivered output power at a desired level; and setting the tuning capacitive values of the first tuning capacitive network to the tuning capacitive values.

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 damping control system disposed at a location of an antenna resonant circuit detects an exciter signal produced by a remotely located EAS transmitter. The damping control system generates a switch control signal in response to the detection of an EAS exciter signal burst. The switch control signal is used to reduce a Q factor of the antenna resonant circuit by selectively controlling at least one switching element connected to the antenna resonant circuit. The damping control system controls a timing of the switch control signal so as to reduce the Q factor at a predetermined time selected to reduce ringing at a trailing edge of each periodic burst.

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 system for monitoring and controlling shopping cart usage comprises a wheel assembly that attaches to a shopping cart. The wheel assembly includes a wheel, a brake that can be activated to inhibit rotation of the wheel, a controller that controls the brake, a VLF receiver, and an RF transceiver. The RF transceiver may, for example, operate in a 2.4 GHz frequency band. In some implementations, the RF transceiver may be used to detect entry of the shopping cart into a checkout area of the store, and the VLF receiver may be used to detect that the shopping cart is exiting the store. The controller may activate the brake if the shopping cart attempts to exit the store without first passing through a checkout area.

A system for monitoring and controlling shopping cart usage comprises a wheel assembly that attaches to a shopping cart. In some embodiments the wheel assembly includes a wheel, a brake that can be activated to inhibit rotation of the wheel, a controller that controls the brake, a VLF receiver, and an RF transceiver. The RF transceiver may, for example, operate in a 2.4 GHz frequency band. In some implementations, the RF transceiver may be used to detect entry of the shopping cart into a checkout area of the store, and the VLF receiver may be used to detect that the shopping cart is exiting the store. The controller may activate the brake if the shopping cart attempts to exit the store without first passing through a checkout area.

A system for monitoring and controlling shopping cart usage comprises a wheel assembly that attaches to a shopping cart. In some embodiments the wheel assembly includes a wheel, a brake that can be activated to inhibit rotation of the wheel, a controller that controls the brake, a VLF receiver, and an RF transceiver. The RF transceiver may, for example, operate in a 2.4 GHz frequency band. In some implementations, the RF transceiver may be used to detect entry of the shopping cart into a checkout area of the store, and the VLF receiver may be used to detect that the shopping cart is exiting the store. The controller may activate the brake if the shopping cart attempts to exit the store without first passing through a checkout area.

A motorized cart retriever, which may be a cart pusher or a cart puller, can apply a force to a nest of human-propelled, wheeled carts to facilitate retrieval of the carts. The cart retriever can include a transceiver configured to wirelessly receive cart status information from cart transmitters of the wheeled carts and wirelessly report event data to a control unit. The cart status information may include an identification of the cart transmitter, a location of the cart, a lock or unlock status of a cart wheel, a misuse condition, etc. The event data can include the cart status information, a number of wheeled carts being retrieved, etc. The cart wheel may include a brake. The transceiver may communicate a message to the cart wheel to keep the brake unactuated during retrieval. The control unit may analyze the event data to detect traffic patterns of the carts.