The parking-lot boundary is part of the cart
A cart-containment system turns the edge of a supermarket parking area into an invisible tripwire. A wire buried in the pavement carries an electrical signal, producing a magnetic field along the route where the store wants carts to stop. The wire can be laid around the lot’s perimeter or near entrances to nearby roads.
A signal sets off a brake in the wheel
A specially equipped cart wheel contains a sensor and a braking mechanism. As the wheel approaches the buried wire, the sensor detects its signal and activates the brake. Because the mechanism is built into the wheel, the cart can roll normally across the rest of the lot without a person steering it back.
The system depends on a deliberate pairing: the buried wire defines the boundary, while the cart’s fitted wheel responds to it. That makes the boundary adjustable when a store changes its parking layout, but it also means the brake is not a general-purpose feature that will stop every cart.
Containment without a fence
A physical barrier would block cars and pedestrians as well as carts. The wire instead creates a boundary that is largely invisible to people moving through the lot but meaningful to equipped carts. When a cart reaches it, the sudden stop makes crossing the line difficult—helping keep carts from rolling into traffic or straying far from the store.
