How Scythe Robotics achieves centimeter-level precision with Point One Navigation

At a glance: Scythe Robotics needed centimeter-level precision for their autonomous lawnmower, Scythe M.52. Traditional GPS wasn't accurate enough, and existing RTK solutions were too expensive and difficult to scale. Point One Navigation provided the answer with its global network of base stations and scalable RTK service. This partnership enabled Scythe to achieve precise path planning, consistent coverage, and truly autonomous operation, all critical to their delivery of precise turf management for commercial lawn care.

A vision for smarter, greener lawns

The quest for truly autonomous robots often hinges on one crucial factor: location. Knowing where you are with pinpoint accuracy is the bedrock of any sophisticated robotic system, especially when navigating the unpredictable outdoors. For Scythe Robotics, the creators of Scythe M.52, the world's first fully autonomous electric commercial lawn mower, this challenge was paramount. They needed a positioning solution that wasn't just good, it had to be centimeter-level precise.

The challenge: From 5 meters to 5 centimeters

Traditional GPS/GNSS, with its 5-meter accuracy, simply wouldn't cut it for a robot tasked with meticulously maintaining green spaces. Think about it: a lawn mower robot mowing grass can’t afford overlaps of several meters. And Scythe’s M.52 isn’t your average lawn mower. It’s an electric powerhouse designed to help landscaping teams work smarter, reducing noise, emissions, and labor while maintaining the pristine look of parks, campuses, and golf courses. 

But to mow with precision and reliability, day in and day out, M.52 needed more than sharp blades and a sleek design. It needed localization technology that could plot, save, and repeat exact paths while adapting to changing environments.

Scythe’s engineering team knew that using GNSS for absolute positioning was crucial to their approach, and early development of M.52 revealed key requirements for any potential network partner:

• Precision location: Traditional GNSS offers accuracy within 5 meters—not nearly enough to ensure safe, clean, and consistent mowing.
• A reliable network: Testing revealed several RTK solutions that were unreliable, especially in remote areas that lacked base station density.
• An external, comprehensive base station network: Installing individual base stations at customer locations was time consuming and didn’t allow for scalability.

For Scythe, these requirements were non-negotiable. They needed a solution that was cost-effective, scalable, and ready to work in the real world, not just in ideal conditions.

Enter Point One’s Polaris RTK (Real-Time Kinematic) corrections, a technology that leverages GNSS correction signals to amplify GPS precision by a factor of 100, shrinking the error from 5 meters to a mere 5 centimeters or less. This level of accuracy unlocks a world of possibilities for robotics, enabling precise path planning, consistent coverage, and ultimately, truly autonomous operation. Jack Morrison, CEO of Scythe, put it best: “Having absolute global positioning in seconds is a superpower”.

Making integration simple and scalable

Integrating Polaris RTK into M.52 was remarkably smooth. In fact, according to Morrison, the transition took just seven days: “We asked ourselves, ‘How quickly can we integrate a solution and get it on a robot?’ It took a week.”

Point One also provided Scythe with an easy-to-integrate hardware solution for corrections delivery. This interface between hardware and software serves as the mower’s primary location sensor, pairing seamlessly with Polaris RTK corrections, creating a robust localization system. This precision enables M.52 to tackle diverse environments, from wide-open fields to areas with limited satellite visibility, without missing a beat or blade of grass. And most importantly, the wide coverage of Point One’s Polaris RTK corrections network allows Scythe to deploy their mowers quickly and efficiently, without the need to install costly and time consuming local base stations. 

Localization, everywhere

Even with a reliable RTK corrections network, GNSS receivers work best in clear skies, and M.52 doesn’t always operate in open sky environments. In fact, GNSS signals from satellites struggle with overhead obstacles like buildings and trees, hindering signal reception. Furthermore, the availability of correction signals often require expensive subscription services, creating a barrier to entry for many innovators. And perhaps most critically, it's difficult to know when the system is providing accurate data. For example, a sensor confidently feeding incorrect information is a recipe for disaster when working with autonomous robots.

Scythe's solution: a symphony of sensors

Scythe tackled these challenges head-on. From day one, they knew centimeter-level accuracy was essential for their autonomous mower. They understood the inherent duality of mowing environments: wide-open fields, ideal for RTK corrected GNSS, versus crowded areas with limited sky view but rich visual information. Their solution? A sophisticated sensor fusion system. It consists of eight cameras to provide 360-degree vision, complemented by a high-quality antenna receiver, two IMUs (Inertial Measurement Unit), and 12 ultrasonic sensors. This sensor fusion stack coupled with Point One’s Polaris RTK overcomes the varied challenges of autonomous robotic lawn mowers outside. While Scythe developed their own impressive system, Point One also offers a fully integrated solution, via the use of its Atlas INS (Inertial Navigation System), that allows for dead reckoning. Crucially, Polaris RTK corrections integrates seamlessly with either Atlas or Scythe's in-house system.

Even with a comprehensive sensor stack the journey to precise positioning wasn't without its bumps. Scythe’s second-generation prototype faced a significant EMI (electromagnetic interference) issue. The onboard computer was disrupting the GPS signal. The solution? A high school intern armed with copper tape and a soldering iron constructed a Faraday cage, shielding the electronics and restoring signal integrity. This ingenuity combined with lessons learned about antenna placement, highlights the practical challenges of integrating complex systems. Innovation is an iterative process and autonomous robotics is still in its infancy, but companies like Scythe are paving (or mowing) the way.

Building the future of autonomy together

Scythe's partnership with Point One has been instrumental in the company’s growth. Over the years Scythe has deployed numerous base stations via Point One's network, expanding their operational footprint. This collaboration has allowed Scythe to focus on what they do best – building cutting-edge autonomous robots – while Point One provides the reliable, high-precision positioning foundation. The result? A future where robots and humans work together seamlessly, creating and maintaining the green spaces we all enjoy.