I have been using the Navimow for a few months now, and my impressions are positive but mixed. Let’s start with the positives.

When the Navimow works correctly, it is amazing. You can schedule your lawn to be mowed every day, in the middle of the night if you want, so that it looks freshly cut all the time. The Navimow usually leaves beautiful, parallel cut lines that instantly improve the appearance of your lawn.

Beautiful stripes from the Navimow.

The problem is, put as simply as possible, I don’t trust my Navimow to operate autonomously. I’ll go into more detail below, but I’ll mention the two largest problems:

1. The Navimow frequently gets stuck. The included wheels are simply terrible. At least on my lawn, the device often gets itself stuck in the lawn or garden bed, and ends up digging a rut trying to get itself out. Segway’s Navimow Off-Road tires — which Segway’s support provided to me for free (normally ~$100) — do indeed help. And I found that third-party Spikes help even more. More on this below under Traction.
2. The mower is unpredictable. I don’t think there is a single root cause of this; I think it is caused by GPS imprecision, traction control, and “Vision Fence” (the vision AI) failures. Whatever the cause, the Navimow cannot be trusted around “dangerous” boundaries. This includes cliffs, like a curb. But it also includes V-shaped gulleys that separate the lawn from a raised mulch bed. If you let the Navimow near these dangerous areas, it will inevitably fall or get stuck. I have given up trying to get my Navimow to mow the strip of grass adjacent to the curb.

Setup

If you watch video reviews, people will remark that setup is very quick and easy. While it’s surely easier than having to run a boundary wire, finding a location for the base station and antenna was non-trivial for me. One thing that was unclear to me when purchasing was that the antenna and base station need to have a good view of the southern sky, which greatly limited where I can put them. I also didn’t want to put the base station on the grass, since that would kill it. I ended up putting the base station on a raised mulch bed, and running the power cord through a window. It’s not ideal, but it works. Now, normally the Navimow cannot climb onto mulch because of its terrible wheels. So I put down a welcome mat to help the Navimow “climb” the mulch. It took me a while, but I eventually figured out that Vision Fence would cause the Navimow to ignore the mat sometimes and try to climb the mulch a few feet away, at which point it would often get stuck. But fortunately, after disabling Vision Fence near the mat, the robot was able to consistently reach the base station.

My “welcome mat” solution to allow the Navimow to reach its base station on the mulch.

The other aspect of Setup is mapping.

Mapping

The first few times you make a map on the Navimow, it’s pretty fun. You literally use the robot like a remote control car and draw an outline of the area. This does work pretty well, but it quickly becomes burdensome. Making adjustments to the map also requires driving the robot around. If you want to mark an area as off limits, you need to drive the robot around. For small adjustments, it is both clunky and inconvenient. If the robot is not in the area, I don’t want to drive it over just to make a small adjustment. It would be better to overlay a satellite image and allow adjustments to be made directly from the app.

It’s also imprecise to use the large robot to mark off small areas to avoid, such as a sprinkler. It’s unclear what the off-limits areas mean. If the Navimow is in a position marking an off-limits area, does that mean the center of the Navimow is off-limits, or any portion of where the robot covers is off-limits? Similarly, when operating, are all portions of the Navimow prohibited from entering off-limits areas, or just the center?

A similar problem occurs when trying to use the robot to mark steep and difficult terrain areas. To mark these as off limits, you need to drive the robot around them. But because they are difficult areas to traverse, obviously driving the robot there can be difficult!

Obstacle Avoidance

Obstacle avoidance uses the Navimow “Vision Fence” feature. I have found that it works very well for avoiding dog toys and large sticks in the backyard. Unfortunately, it fails to detect many other obstacles. I’ve seen it run into my mailbox, a gate, and run over sprinklers and flags. When it runs into sturdy objects like a mailbox or gate, it then spins its wheels and digs a rut before realizing it hit something.

Vision Fence also seems to detect phantom objects. I have encountered this often in channels, which are paths connecting one mowing area to another. When Vision Fence is enabled, it will inexplicably decide to move a few feet away from the designated channel. Since I have a mat at the location of the channel to help the Navimow get on the mulch, this few feet avoidance results in the robot getting stuck. It would be nice to have an indication in the app of when an obstacle is detected by Vision Fence. But at the moment, there is no way to know why the robot decided to veer off its course.

A channel in which Vision Fence frequently caused the Navimow to get stuck.

Here is a video of the Navimow absolutely failing to detect an obstacle. Inexplicably, instead of backing up, it doubles down and tries to motor through the gate, making fresh ruts in the grass it just mowed.

Navimow attempting to run through a fence gate and creating ruts in the process.

Navimow attempting to run through a fence gate and creating ruts in the process.