Abstract
Traveling along straight lines and headland turning are two common motions during the automatic guidance of agricultural machines. However, most studies focus on accurately following parallel tracks in the field and seldom consider the maneuvers at the end of each row. Moreover, numerous studies have mainly focused on planning the global trajectories in the entire field to increase field efficiency, and very few works are related to maneuver generation and vehicle control in headlands. In this study, a feedforward-plus-proportional–integral–derivative controller for a differential drive robot in headland turning was developed. The feedforward-plus-proportional–integral–derivative controller consisted of a feedforward and a feedback loop. The feedforward loop was designed based on the heading errors of a lookahead point on the planning path. The feedback loop was designed based on radial errors to improve the tracking accuracy. Field comparison tests of feedforward, feedback, and feedforward-plus-proportional–integral–derivative controllers were conducted. Experimental results showed that the feedforward-plus-proportional–integral–derivative had better tracking results and took less turning time.
Highlights
Mobile robots play a significant role in many agricultural applications as they reduce human labor and enhance the operational safety
To test whether the proposed algorithm works practically on the differential drive robot platform and to compare the performance of the FPID, feedforward, and feedback controllers, several experiments are made for the robot platform
An FPID headland-turning controller for a differential drive robot was developed in this study
Summary
Mobile robots play a significant role in many agricultural applications as they reduce human labor and enhance the operational safety. The need for autonomous navigation systems of mobile robots has been recognized in different agricultural tasks such as planting, spraying, fertilizing, cultivating, harvesting, thinning, weeding, and inspection.[1,2] Traveling in straight lines and headland turning are two common motions during the automatic guidance of an agricultural machine. Autonomous guidance would require the robot’s capability to make turns in the headland and enter the operation row. Several factors such as space availability, vehicle limitations, obstructions, and time taken to turn have to be taken into account when controlling robot during headland turning. Most studies focus on accurately following parallel tracks in the field, and seldom consider
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