| Resumo: |
Two off-the-shelf John Deere utility mowers were modified for X-by-wire control for the purposes of constructing autonomous vehicles usable in sports-turf mowing applications. The purpose of these mules was to enable the gathering of requirements and customer feedback on such a system. The environment selected initially was that of a baseball stadium. These areas can be characterized as flat, highly controlled and well-groomed, for which precise mowing patterns are necessities. Typically the operators of these mowers are highly skilled; an autonomous system has the benefits of saving time and labor, permitting the efficient usage of less-skilled employees, and allowing skilled personnel to focus on more complex tasks (such as infield mowing and warning track grooming). For this application, there are stringent requirements on navigation, path planning and path tracking, while the safeguarding requirements are challenging, but more relaxed than, say, the requirements for golf courses. The calculation of precise position and orientation in this environment requires sensor fusion and is complicated by the fact that frequently the operating area is surrounded by very high walls, limiting sky visibility and preventing the usage of GPScentric navigation systems. Furthermore, it was desirable to mature the design far enough so that it could be operated regularly by non-technical operators. These results were achieved by developing an accurate local positioning system, making the hardware and software subsystems robust against unexpected failures and constructing a very simple graphical user interface. This paper will review other relevant existing systems, describe the hardware and software systems utilized, and conclude with descriptions on the performance, customer learning, and description of properties of autonomous systems that enable their integration into a worksite.
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