Design of the locomotion system for a new robot for precision agriculture in greenhouses

Precision Agriculture, developed in the United States in the late 1970s, is now widely used with the aim of improving the quality and sustainability of agricultural productions through the right treatment, in the right place, at the right time. However, in many countries such as Italy, it has found significant limitations, since the small size of farms and the high average age of farmers prevent its mass diffusion. In modern agriculture, relying on Precision Agriculture concepts, mobile robots have become a key ally, for both data collection and accurate plant maintenance operations. By automating different tasks, these intelligent machines maximize production, increase its quality, reduce cost and improve the precision of farming operations. In this context, among the Agritech projects, the idea of the Agricultural Mate Robot (AgriMaRo) was born to support farmers in a sustainable way, adhering to the strategy proposed by the United Nations in its development goals. The practical role of the AgriMaRo robot is to be a versatile (flexible and modular) solution for farming in fairly-structured environments, such as greenhouses. AgriMaRo will be an omnidirectional three-wheeled robot, capable of varying its track. In addition, it will be able to accommodate various types of tools to perform plant management tasks. This thesis work has as its main objective the design of the robot's locomotion system, namely all the organs or devices that contribute to its movement from one place to another. Given the objectives of the project and analysed the state of the art of mobile agricultural robots, the work was structured in two fundamental and distinct phases. As a first step, it was necessary to study the kinematics of AgriMaRo, in order to define a mathematical relationship between the velocity twist, and therefore the trajectory, of the robot and the required angles and velocities of the actuators. Having defined this, the focus shifted to dynamics. In this case, it was necessary to evaluate the torques and forces required to operate properly on unstructured soils, with specific compactness and density. This task was carried out by means of both calculation models and experimental tests and the results obtained, have been used to realise the executive project of the locomotion system and to choose the commercial components. The concept underlying all the design choices was omnidirectionality, which was intended to be achieved through the coordinated control of the three different steering wheels. Although it was not integrated into the final design, the possibility of integrating suspension was also analysed, considering the need to filter out imperfections in the terrain, in order to have more reliable results in data acquisition and to operate with greater precision. Briefly, in a world facing the problem of creating a sustainable future, the AgriMaRo robot represents a tangible technical solution to answer this challenge in the agricultural environment. In particular, its flexibility and modularity makes it the perfect ally for all the operations in greenhouses.