Every robot mower needs to know where the lawn stops. The older way is a wire you bury or peg around the edge. The newer way is a boundary drawn on a map, which the mower follows using satellite positioning, cameras, LiDAR or a mix. Both work. They suit different yards.
Boundary wire
The wire carries a weak signal from the base station. The mower turns back when it detects it. You lay it around the lawn edge and around anything inside the lawn the mower should avoid.
- Good for: yards with heavy tree cover or tall buildings close by, where satellite signals are poor. It doesn’t need the sky, the internet or good light.
- The catch: installing it takes an afternoon or more, and changing the garden later means moving the wire. A wire cut by a spade or an aerator stops the mower until it’s repaired.
Wire-free: RTK satellite positioning
RTK corrects satellite positioning to around centimeter accuracy. You set the boundary by driving the mower around the edge with your phone or by drawing it in the app. Corrections come from an antenna you install in the yard or over the cellular network, depending on the model.
- Good for: open lawns, several separate areas, and gardens that change. Moving a bed means editing a map.
- The catch: it needs a clear view of the sky. Thick tree canopy, a tall house wall or a narrow side yard can weaken the signal. Network RTK needs cellular coverage at the lawn.
Wire-free: cameras and LiDAR
Vision models recognize grass and obstacles with cameras. LiDAR models measure distances with a laser sensor and build a map. Several current mowers combine one of these with RTK so each covers the other’s weak spots.
- Good for: yards under trees where RTK struggles, and lawns where seeing obstacles matters.
- The catch: cameras depend on light, so check what the maker says about night mowing. Greenworks, for example, notes that low light can reduce obstacle avoidance on the C40.
A quick way to decide
- Mostly open sky over the lawn and a garden you like to change: wire-free RTK, or RTK with vision.
- Lots of tall trees: look at LiDAR or vision models, or a boundary wire.
- No reliable internet or cell signal outside: boundary wire avoids depending on either for navigation.
The model table lists how each current model navigates, according to its maker.