When the robot was moving my lawn, most of the time it was moving over the middle of the lawn, cutting the same patch over and over. I had some trees in a corner, and a swing in the other, and the robot newer quite got down behind them. So I made a simple hack. I created 2 loops of the guide wire instead of one.the first loop, goes around the garden, and left around the trees. The other loop, goes the other way around, and right around the trees. Controlling it, is two correspondence switches normally used for outdoor lighting. This forces the robot to spend time, on the difficult parts, instead of just happily moving the same patch over and over. An upgrade, could be to use relays instead, and then use a microcontroller to decide the pattern. Using a sensor to see, if the robot had been in the charger, and if so, switch to the other loop.