For twenty years a robot mower meant a boundary wire pegged around every bed, tree and path, and a spring spent finding the break that stopped the machine leaving its dock. Wire-free navigation has become the default selling point of new models, and the installation genuinely is shorter. What changed is which part of the garden decides whether the machine works.
The three navigation systems on sale
- Boundary wire: a buried or pegged perimeter loop the mower senses. Unaffected by tree cover or weather, but physically laid once and repaired by hand.
- RTK satellite: a fixed reference antenna corrects the mower's satellite position to centimetre accuracy. No wire, but the antenna and the mower both need sky visibility.
- Camera vision: on-board cameras read grass edges and obstacles. No wire and no antenna, but performance depends on light, contrast and how clearly the lawn edge is defined.
The practical consequence is that garden shape now selects the technology. An open suburban lawn suits RTK. A garden under mature trees, or one broken up by a house wall on two sides, will lose the satellite correction exactly where the machine is hardest to retrieve — and a wired install remains the reliable answer there.
Check the slope figure, not the area figure
Area claims assume flat ground and a full duty cycle. Manufacturers publish a separate maximum slope, usually as a percentage gradient, and that number is the one that decides whether a mower can work the awkward corner of a garden at all.
Safety rules have not changed
Blade shut-off on lift and tilt is standard across the category, and product-safety regulators treat robot mowers as powered garden machinery rather than appliances. Obstacle avoidance on camera models reduces, but does not remove, the risk to small animals and to anything left on the lawn. Manufacturers and safety bodies consistently advise scheduling runs in daylight and keeping the lawn clear during a cut.
What it costs to keep one running
Blades are the routine consumable and are cheap; the battery is not. Before buying, look up the published price of a replacement battery pack and whether the manufacturer sells one at all — on an eight-to-ten-year machine that single figure decides whether year five is a repair or a replacement.
Wire-free is an installation feature. Whether the mower finishes the lawn is still decided by slope, tree cover and what the manufacturer will sell you in year five.
