Laser Measurement Systems (LMS) are used in autonomous agricultural vehicles for guidance and obstacle detection purposes. In the particular case of agricultural vehicles, the efficiency of LMS measurements is affected by mechanical vibrations induced by the operation of these machines on uneven terrains. The objective of this study was to evaluate the effectiveness of a mounting system capable of reducing the transmission of mechanical vibrations to an LMS sensor installed on an agricultural tractor for the purpose of improving the detection accuracy of obstacles during field operation.
A stabilization system (SS) was designed for a SICK LMS 291-S14 scanner. The LMS sensor and the SS were installed on an agricultural tractor to scan four objects positioned at known locations in the field. An experimental analysis was carried out to evaluate the detection accuracy of the LMS sensor under different operating conditions: with and without SS; with and without support bars (S); and for different types of terrains (in terms of roughness) and field operating speed. The detection accuracy of the LMS sensor was assessed by determining the difference between the known location of the four objects and their corresponding estimated location from the LMS measurements.
The increase of tractor speed had a negative effect on the accuracy of the LMS sensor with an increase in the positioning error of up to 75%. However, it was not possible to establish a clear relationship between terrain roughness and the accuracy of the LMS sensor. The addition of the S systems positively affected the accuracy of the LMS sensor and resulted in a 41% decrease of the average positioning error from 0.340 to 0.201 m. Finally, the used of the SS mounting system decreased the average positioning error by 57% from 0.382 to 0.161 m. These experimental results confirmed the effectiveness of the joint use of the SS and S mounting systems in improving the accuracy of the LMS sensor mounted on an agricultural tractor through a reduction in transmitted vibrations.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OOU-OLD./22832 |
| Date | 03 May 2012 |
| Creators | Fresquet Periu, Carlos |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Thèse / Thesis |
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