How does a Robot Lawnmower Work?

Years of development has gone into making robot lawn mowers work around the clock to deliver a well kept lawn despite bad weather, complex shapes, steep slopes, narrow passages and other obstacles.

The quick answer:

A Robot Lawnmower works inside an area defined by a boundary wire. Cutting little and often, it moves in a irregular pattern to prevent tracks forming. Returns to its charging station by itself to charge and then restarts. The size and complexity of the lawn will dictate how long the Robot Lawnmower should operate each day.

Now that is essentially what happens but their is a lot that goes into achieving this.  So to give you the best answer we will look at the Market Leader which is the Husqvarna Automower.

So in no particular order lets look at some of the features which allow a Automatic Robot Lawnmower to work!

Automatic charging

The charging station transmits a signal to the wire that guides the mower where to cut and also guides it back to the charging station.

When its time to recharge, the mower finds the charging station by one of free methods.

  • Picking up a signal from the charging station antenna.
  • Following a guide wire back to the charging station.
  • Following the boundary until within reach of the charging station signal.

Guide Wires

Guide Wires are extra wires that are laid from the charging station towards a remote part of the lawn or through a narrow passage and then connected to the boundary wire.

The benefit is a much shorter search time when the mower is returning to charge.

Boundary Wire

The boundary wires are pegged to the lawn or buried just below the surface. The Mower stays inside the boundary wire while operating.


The boundary wire can be used to demarcate areas inside the working area by creating islands around obstacles such as flowerbeds, bushes and fountains. The wire is laid up to and around the area to be demarcated and then return it back along the same route. when the boundary wires to and from the island are laid close together, the robotic lawnmower can drive over the wire. Its hard to picture all of this so take a look at the picture below.

Random Movement Pattern

Given the correct amount of time on the lawn the mower will cover all parts even if the lawn is complex, contains trees, flowerbeds, passages etc. It also allows the grass to get cut from different directions which creates a smooth carpet-lie surface.

Husqvarna Automowers can pass through passages as narrow as 60cm when following a guide wire.

Automatic passage handling enables the mower to vary the distance from the guide wire each times its follows to minimize tracks forming.

Collision and lift sensors

Collision and lift sensors increases safety.  when the mower runs in to an object it will reverse, turn and choose another direction. If it is lifted the blade and mower stop immediately.

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