Welcome to Zupt Autonomous Products and Technology Introduction to Commercial Autonomous Mowing series. This article is the 4th in our series “An Introduction to Autonomous Mowing.” This week we continue forward from our post on the precise location and how Nomad maintains a constant knowledge of its location through GNSS and imagery to improve productivity. In the future, you can expect to see Stories from our Engineers and Stories from the Field as part of additional Blog series.
Mowing production is all about clean-cutting/mulching at speed with minimal overlap. Nomad optimizes efficiency by fully utilizing the deck width and not passing over areas that have already been cut. When mowing multiple smaller “residential” areas, the time It takes for Nomad to get off the trailer to start mowing and to get back onto the trailer must be considered. Still, it should not impact the overall productivity. Nomad is a 4-wheel drive, 4-wheel steering 60” (1.5m) wide deck as described in the introduction. Nomad also has a very unusual party trick. By automatically transforming its leg configuration, Nomad can move from what we call a “fat” cut (60”) down to a “skinny” width of 31”. This allows Nomad to transit through a 36” wide gate and then transform back to a 60” mower to maintain maximum productivity.
Image: Nomads 60" fat mowing width
The 4-wheel drive allows Nomad to be very safe and productive on slopes. There are no concerns about the skid steer issues of the front of the mower rolling down the hill. Nomad can also crab or cut moving in any direction due to the unique 4-wheel steering. Protecting the quality of the turf is at the top of our minds, and damage due to excessive torque in any wheel is protected against by the unique torque balancing enabled via the brain.
Image: Nomads 30" skinny mowing width
Path Planning
In the previous blog, we defined the area Nomad will mow within and how there are “no go” areas that Nomad must drive around. There will be many obstructions on any job site, including pipeline markers, road signs, flower beds, trees, utility boxes, storm drain covers, etc. We use a specific piece of software known as a “global path planner” that takes the area inside our outer bounding polygon, along with any inner obstruction polygons, and optimizes the primary path the mower will follow to cut the site as efficiently as possible. This software has a kinematic model (A kinematic model is a mathematical description of the robot: its functional dimensions and the degrees of freedom and movements it can make) of Nomad defined within it. Understanding how Nomad can turn and how flexible Nomad can be, allows this global planning software to automatically design the fastest route for mowing a specific shape. Multiple mow patterns (at least 4) are developed within this global planning capability to ensure that tire ruts do not start to mark the turf, and alternate mowing patterns are available for repetitive weekly mowing at the height of the cutting season.
Once Nomad is working on-site, another piece of software known as the “local path planner” is constantly optimizing the path to be mowed, considering the obstructions seen with the perception sensors and the optimal conditions seen that day.
Reporting Tools
In addition to the mechanical and technical production influences, we have an extremely robust reporting system. We will work with each client to create a report template that provides the operational data required. These are some samples of reporting available.
Acres per Hour
Motor Run/Down Time
Fluid Levels and Temps
Time per Site
Non-productive time
Engine Temps
Engaged Blade Time
The imagery of unknown, unknowns
Time remaining on Mow Site
Position of Mower 24/7
These reporting capabilities will allow you to evaluate efficiency, create improved schedules, and be proactive with regular maintenance. The key will always be to provide safe, highly productive mowing.
Thank you for continuing to read our Introduction to Autonomous Mowing. In our next session, we will dig into the sensors in our “instrument castle” on Nomad's top. The coupling of these sensors is at the heart of what makes Nomad unique in the industry.