For the best part of two decades, buying a robot mower meant spending a day on your knees with a spool of wire, a plastic peg and a mallet. The wire was not a detail of the installation. It was the installation.
That is no longer true, and it is worth understanding why — because the technology that replaced the wire also changed what a robot mower can do once it is running.
What the wire was actually for
A first-generation robot mower had no idea where it was. It drove more or less at random, and when it crossed the buried loop it sensed the signal and turned around. The wire was not a map; it was a fence. Everything the mower knew about your garden was "I have just hit the edge".
That has three consequences you may recognise if you have owned one. It cannot plan a route, so it covers the same patch four times and misses another entirely. It cannot be told to mow only the front lawn today. And moving a flower bed means digging the wire up again.
RTK: centimetre-level position from satellites
RTK stands for Real-Time Kinematic positioning. A plain GNSS receiver — the kind in your phone — is accurate to a few metres, which is useless for a machine that has to stay off the flower beds. RTK fixes that by adding a second, stationary receiver: the base station you mount on a wall or a stake in your garden.
The base station knows it is not moving. Any drift it measures must be error introduced by the atmosphere, and it broadcasts that correction to the mower several times a second. Applied to the mower's own reading, it brings position down from metres to a couple of centimetres.
Once a mower knows where it is that precisely, the boundary stops being a physical object and becomes a line on a map. You walk the perimeter once from your phone, and the shape is saved. Want to exclude the trampoline? Draw around it. Moved the trampoline? Draw again.
Where satellites struggle, and vision takes over
RTK needs sky. Under a mature tree, along a tall hedge, down the side of a house or against a fence line, the number of visible satellites drops and the fix degrades. Every wire-free mower on the market meets this problem; the difference is what it does next.
The LYMOW One Plus runs a second navigation engine alongside RTK: VSLAM, or Visual Simultaneous Localisation and Mapping. Binocular cameras track fixed features around the mower — the corner of a shed, a fence post, the edge of a path — and work out how far it has moved relative to them. No satellites required.
The two systems are complementary rather than redundant. RTK is absolute and never drifts, but needs an open sky. Vision works anywhere there is something to look at, but accumulates small errors over distance. Running both, the mower leans on whichever is currently trustworthy and keeps a continuous position through the dead spots.
Mapping is not the same as seeing
It is worth separating two things that get sold as one. Mapping tells the mower where the lawn is. It says nothing about what has turned up on the lawn since the map was drawn.
That is a separate job, handled by the same binocular cameras working as an obstacle-avoidance system: a coiled hose, garden furniture that was not there last week, a football, a hedgehog out at dusk. The mower classifies the object, steers around it and carries on rather than nudging it or stopping dead and waiting for you.
What setup looks like now
- Mount the RTK base station somewhere with a clear view of the sky and mains power.
- Drive the perimeter once from the app, the way you would steer a remote-control car.
- Split the map into zones — the One Plus supports up to 80 — and mark no-go areas.
- Set a schedule per zone, and let auto-recharge and resume handle the rest.
An afternoon of trenching has become well under an hour of walking around with a phone. More importantly, the mower now knows your garden well enough to mow it in planned, even lines instead of bouncing around inside a fence.
