New Tech Tuesdays: Autonomous Robotic Lawnmowers: The Future of Lawn Care

by Rudy Ramos, Mouser Electronics


New Tech Tuesdays

Join Rudy Ramos for a weekly look at all things interesting, new, and noteworthy for design engineers.

What could be better than sipping a cold beverage under the shade on a hot summer day, admiring your freshly cut lawn? How about sipping a cold beverage while watching an autonomous lawnmower cutting your lawn? Husqvarna, a Swedish company founded in 1689 and synonymous with chainsaws, has introduced a series of robotic lawnmowers—Automower— equipped with Husqvarna EPOS (Exact Positioning Operating System) navigation and built-in ultrasonic sensors that promise to keep your lawn in perfect shape, allowing you spend your weekend time the way you want. An Automower Connect app connects the robotic lawnmower to your smartphone for easy, smart-home integration, allowing the robotic lawnmower to perform the hard work quietly and autonomously.

The Automower employs a fusion of intelligent technology, but GPS navigation and ultrasonic proximity sensors are the two key technologies that give the Automower its autonomy. The combination of these two technologies enables the Automower to map out the service area and learn. It’s up to the onboard microcontroller unit (MCU) to handle the rest of the lawnmower’s operation, including power management, mechanical drive, communications, and navigation.

Collision Avoidance: A Bat-Inspired Technology

Ultrasonic sensors work by emitting chirps (sound >20kHZ – hence “ultra”), like bats, and measuring the time difference between the transmission of the chirp and the echo return received. The time difference calculation is then converted into distance by the onboard controller. Ultrasonic sensors generally work as a pair: a transmit and a receive sensor. Ultrasonic sensors are typically placed very near each other to help mitigate errors due to acoustic beam angle alignment and scattering of the sound as it hits solid objects in its path. These sensors can also be integrated into one transceiver sensor to further minimize error and reduce their footprint. In the case of Husqvarna’s Automower, ultrasonic sensors are used for object detection and collision avoidance in the cutting path of the mower. The mower will slow down when objects like outdoor furniture, ornaments, pots, and pets are detected. Automower changes course and continues mowing the lawn if an object is detected.

From Satellite to Robot

Autonomous robots that rely on one of the Global Navigation Satellite Systems (GNSS) for their navigation incorporate a receiving device to determine their location (latitude, longitude, altitude, and time) with extreme precision. In the case of GPS, a network of 24 satellites orbits the Earth at an altitude of about 20,000km (13,000 miles). Like stars in a constellation, these satellites are constantly broadcasting their position to Earth. GPS receivers on Earth—like those found in autonomous robots, vehicles, and cell phones—can lock onto more than one of these satellites at a time. Using the satellite’s broadcasting information, they can extrapolate their terrestrial position with accuracy down to meters or even within a few centimeters depending on the atmospheric conditions, signal blockage, satellite’s geometry, and the receiver’s quality.

As part of this week’s New Tech Tuesday, we examine two products that contribute to applications driving the advancement of autonomous robots.

These CUI Devices CUSA series ultrasonic sensors are available as either receivers, transmitters, or transceivers. They feature beam angles from a narrow 7 degrees to wide 120 degrees, various frequency ranges from 23kHz to 400kHz, and an operating temperature range of -40°C to 85°C, depending on the sensor. These ultrasonic sensors are in high demand not only for their affordability and capabilities but also for their straightforward design flexibility and ease of integration into autonomous designs, whether robots, drones, or vehicles.

U-blox’s SAM-M10Q omnidirectional patch antenna module delivers a balance between performance and size. U-blox’s M10 precision GNSS platform provides exceptional sensitivity and acquisition time for all L1 GNSS signals. The SAM-M10Q supports simultaneous reception of four GNSS systems (GPS, GLONASS, Galileo, and BeiDou). As a result of the high number of visible satellites, the receiver can select the best signals to maximize position availability even under challenging conditions such as deep urban canyons. Also featured on the SAM-M10Q is U-blox’s Super-S (Super-Signal) technology for improved RF sensitivity in non-line-of-sight situations. With its extremely low power consumption of 37mW in continuous tracking mode with four concurrent GNSS, this module allows for excellent power autonomy without compromising GNSS performance.

Tuesday’s Takeaway

The Automower is just one of many autonomous consumer-grade robots quickly integrating into the smart home ecosystem. These robots are loaded with advanced intelligent technologies and are designed to give homeowners back their time, enhance convenience and security, and potentially provide a more level playing field for those with physical limitations. By using advanced navigation systems that incorporate GPS and ultrasonic sensors, these robots are transforming how we approach household chores and are fast becoming essential components of the modern home.