Design and Control of a Highly Articulated Agricultural Robot

Abstract

Agricultural robots operate in environments with myriad challenges, such as nonflat terrain, nontraversable regions, strict tolerances on deviation from intended trajectories, and long travel distances. Many robots operate in agriculture today, but a large number of them are bespoke and intended for a single application. Repurposing an agricultural robot intended for one application for another typically takes significant effort, even in the case of simple changes such as performing the same task for a different crop.

This thesis presents the design of a robotic platform which is highly maneuverable and easily configurable to accommodate a wide variety of tasks with minimal reconfiguration effort. It is four-wheel steered and four-wheel driven, allowing a number of different operational modes which enable it to follow complex trajectories with tighter turns than many other agricultural robots.

These operational modes are described and evaluated, and different controllers are benchmarked on the robot over various trajectory profiles typical in agricultural settings. A pure pursuit controller is presented as a baseline geometric control algorithm, then a model predictive controller is implemented and tested on the robot. Finally, a mode-switching controller is proposed which reasons about the different operational modes available to the robot and intelligently switches between them to follow more complicated trajectories.