Patent ID: 8571778

Claim:
A system for controlling usage of shopping carts, comprising: a shopping cart wheel assembly that attaches to a shopping cart, the shopping cart wheel assembly having a wheel, a braking unit that inhibits movement of the shopping cart when activated, and a control unit that controls the braking unit, the control unit comprising communication circuitry configured to detect transmissions of a boundary signal, wherein the control unit is configured to respond to the boundary signal by conditionally activating the braking unit; a first transmitter positioned at a fixed location associated with a boundary, the first transmitter configured to transmit the boundary signal; and a second transmitter associated with a mechanized cart retrieval unit, the second transmitter configured to transmit a brake deactivation signal during mechanized cart retrieval, said second transmitter configured to transmit the brake deactivation signal in response to initiation by a retrieval unit operator of a cart retrieval operation; wherein the control unit is responsive to receiving the brake deactivation signal by maintaining the brake unit deactivated regardless of whether the boundary signal is detected, such that the brake unit remains deactivated during mechanized cart retrieval regardless of whether the shopping cart crosses the boundary.