College of Engineering, University of Georgia, Athens, GA 30602, USA.
Department of Entomology, University of Georgia, Tifton, GA 31793, USA.
Sensors (Basel). 2020 Aug 7;20(16):4412. doi: 10.3390/s20164412.
This study proposes an algorithm that controls an autonomous, multi-purpose, center-articulated hydrostatic transmission rover to navigate along crop rows. This multi-purpose rover (MPR) is being developed to harvest undefoliated cotton to expand the harvest window to up to 50 days. The rover would harvest cotton in teams by performing several passes as the bolls become ready to harvest. We propose that a small robot could make cotton production more profitable for farmers and more accessible to owners of smaller plots of land who cannot afford large tractors and harvesting equipment. The rover was localized with a low-cost Real-Time Kinematic Global Navigation Satellite System (RTK-GNSS), encoders, and Inertial Measurement Unit (IMU)s for heading. Robot Operating System (ROS)-based software was developed to harness the sensor information, localize the rover, and execute path following controls. To test the localization and modified pure-pursuit path-following controls, first, GNSS waypoints were obtained by manually steering the rover over the rows followed by the rover autonomously driving over the rows. The results showed that the robot achieved a mean absolute error (MAE) of 0.04 m, 0.06 m, and 0.09 m for the first, second and third passes of the experiment, respectively. The robot achieved an MAE of 0.06 m. When turning at the end of the row, the MAE from the RTK-GNSS-generated path was 0.24 m. The turning errors were acceptable for the open field at the end of the row. Errors while driving down the row did damage the plants by moving close to the plants' stems, and these errors likely would not impede operations designed for the MPR. Therefore, the designed rover and control algorithms are good and can be used for cotton harvesting operations.
本研究提出了一种算法，用于控制自主式、多用途、中心铰接式静液压传动漫游车沿作物行导航。这款多用途漫游车（MPR）旨在收获未落叶的棉花，将收获窗口扩大至 50 天。漫游车将通过多次行驶来收获棉花，当棉铃准备好收获时，就可以进行多次收获。我们提出，一个小型机器人可以使农民种植棉花更有利可图，也可以使拥有小块土地的所有者更容易种植棉花，因为他们买不起大型拖拉机和收获设备。漫游车使用低成本实时动态全球导航卫星系统（RTK-GNSS）、编码器和惯性测量单元（IMU）进行航向定位。基于机器人操作系统（ROS）的软件被开发出来，以利用传感器信息、定位漫游车并执行路径跟随控制。为了测试定位和改进的纯追踪路径跟随控制，首先，通过手动引导漫游车沿着行行驶，获得全球导航卫星系统（GNSS）航点，然后让漫游车自主地沿着行行驶。结果表明，机器人在实验的第一、第二和第三次行驶中分别实现了 0.04 米、0.06 米和 0.09 米的平均绝对误差（MAE）。机器人的 MAE 达到了 0.06 米。在转弯时，RTK-GNSS 生成的路径的 MAE 为 0.24 米。在田地尽头转弯时的误差是可以接受的。在沿着行行驶时，由于靠近植物的茎，误差会损坏植物，但这些误差可能不会阻碍为 MPR 设计的操作。因此，设计的漫游车和控制算法是可行的，可以用于棉花收获作业。
