A mobile robot based watering system for smart lawn maintenance

Lawn maintenance is a tedious task that requires watering, mowing and fertilizing to be carried out at regular intervals to maintain a healthy lawn. Significant wastage and pollution occurs due to improper lawn maintenance practices. With many repetitive and routine tasks being replaced by robotic systems, lawn maintenance could also be achieved using a robotic system that would limit wastage and pollution, ensure a healthy lawn and reduce the work content of the lawn owner. This research presents a prototype robotic system developed to water a lawn efficiently by measuring soil moisture levels. The system comprises a tethered mobile platform and a watering system. The mobile platform is capable of measuring the soil moisture levels at a required depth and controls the water delivery based on pre-set moisture requirements. A novel Coverage path planning (CPP) algorithm was developed to account for the constraints posed by the tether and navigate to all accessible areas within a given lawn layout. The CPP algorithm uses a priori map consisting of environment data and prevalent static obstacles. This paper presents a fully autonomous system, which is able to water the lawn, traversing the path generated by CPP algorithm. The control system of the robot was developed using the Robot Operating System (ROS). The control system is designed in three layers. The higher level provides path planning and decision making, the mid-level provides communication with the hardware and carries out mandatory calculations and the lower level performs reading of sensor inputs and controlling of actuators. The control system was designed in a manner such that it can be remotely monitored and controlled. The developed platform was tested carrying out area coverage while watering a test area.