A system is disclosed for tracking and controlling shopping carts or other types of human-propelled vehicles. In one embodiment, the system includes a wheel or wheel assembly with a braking mechanism that is activated in response to signals received by multiple receivers. The receivers may, for example, include a VLF (Very Low Frequency) receiver for detecting a VLF signal transmitted by a buried cable, and an RF transceiver for communicating over a wireless network. The receivers may, but need not, be included in the wheel. The multiple receivers may be used in combination to control a shopping cart; for example, a command received by a shopping cart's RF transceiver may cause the cart to ignore (not activate the brake in response to) a detected VLF signal.