The other week I bought wheelie bars for Robbie, my Lawnbott 3250. These are two rollers that mount to the undercarriage of the bott. There were no directions, but after turning him on his back it was pretty obvious where the rollers went. Once installed and upright, the addition is practically invisible.
I have a pretty steep hill in my back yard. Without the new parts, Robbie spent a lot of time going up the hill, stopping, restarting, and turning circles. If I walked along beside him and held his nose to the ground, he worked fine - but that kind of defeats the purpose of a robot.
With the wheelie bars installed he goes right up the hill in all but the steepest places. He starts to rear back, hits the rollers, and just motors right along.
The only issue I'm seeing is that if there's a steep drop to the side (say, one wheel goes into a dip) the bott can bottom out. The caster hits the ground, and can act as a pivot point, causing him to rotate in place. On a hill, he ends up sliding past the wire. In some places, when following the wire he gets stuck and digs a trench. That can all be fixed by smoothing the yard out some more.
On the whole, I think it's an improvement.
BtW - the page to order the wheelie bars no longer seems reachable from the Paradise Robotics Lawnbott Accessories page, but can be found with a quick Google search.
