Coverage Path Planning on Headlands for Autonomous Field Operations

By Rick Fennema

Abstract

Justification: In agriculture, labour shortage is becoming more and more of a problem. Furthermore, the increasing weight of the machinery is also increasing soil compaction, which can lead to lower yields. A possible solution to overcome these problems is to use light-weight robots.

Aims: These robots require Coverage Path Planning (CPP) for covering agricultural fields. Much research has already been done on CPP. However, a CPP on headlands is understudied. Therefore, this study aimed to find important design criteria for creating a headland CPP, concerning the width of the headland and required turning manoeuvres, which also deals with the dimensions of the robot-implement combination. Moreover, a headland CPP is proposed in this study.

Methods: The headland CPP in this study is based on a robot with a rear-mounted implement, where the field operation is a seeding or tillage-like operation. Furthermore, the basis of the headland CPP uses a fishtail pattern.

Results and Discussion: The headland CPP is focused on the field corners, which requires a Corner Planning Approach (CPA) for covering the corner area. In this study, two different CPAs are created, which are focused on either a higher coverage or a smaller travelled distance for the corner. For each field corner, the optimal CPA is selected based on the non-covered area and the travelled distance. However, under certain circumstances, the CPAs create infeasible turning manoeuvres.

Conclusions: The most important design criterium for creating a headland CPP is to avoid crossing the field border. Therefore, the physical dimensions of the robot-implement combination are required when designing a turning manoeuvre and determining the headland width. Furthermore, a two-dimensional working area is required to allow proper coverage of the headland by the implement. Moreover, the headland width should be determined using all robot-implement combinations needed for a growing season to ensure feasible turning manoeuvres for all robot-implement combinations.

Synthesis: When creating a (headland) CPP, it is important to take the dimensions of the robot-implement combination into account, because of the swinging behaviour of the implement. Furthermore, for the start and end locations of the paths of a field operation, it is important to take into consideration that the implement is normally not in the same position as the center of rotation, for which the path is defined. This is important to maximize the field coverage.