[WJW]

The problem with this type of robot is that it doesn't scale that well price-wise compared to a mobile type. You'll need longer rails on the sides and the gantry will start sagging after a certain length. Meanwhile something on wheels or tracks has a slightly higher initial investment but has almost zero extra cost for driving a little bit further.

[bobiny]

I see, thank you for explaining. Wheeled robot would take more space between plants and how would it carry a water hose without damaging plants?