Greenhouse Based Orientation Measurement System using Spread Spectrum Sound

Traditional greenhouse robots are heavy and expensive, so a small size with low cost platform is needed. When operating small distributed robots in a greenhouse, a positioning and orientation system will be needed for the accurate control. While the traditional methods of determining orientation have limited application in greenhouses due to the errors associated with indoor GPS compasses or the sensitivity of magnetic direction sensors to magnetic materials in the greenhouse. In this research, we develop methods for determining orientation using a sound signal and two receivers. These methods were then experimentally evaluated in a greenhouse with and without manually removing distance reflection data. After deleting these signal reflection errors, the average accuracy of the two methods was determined to be 3.1° and 2.8°, respectively.