{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,20]],"date-time":"2026-01-20T00:41:38Z","timestamp":1768869698685,"version":"3.49.0"},"reference-count":29,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2011,5,26]],"date-time":"2011-05-26T00:00:00Z","timestamp":1306368000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Error is always present in the GPS guidance of a tractor along a desired trajectory. One way to reduce GPS guidance error is by improving the tractor positioning. The most commonly used ways to do this are either by employing more precise GPS receivers and differential corrections or by employing GPS together with some other local positioning systems such as electronic compasses or Inertial Navigation Systems (INS). However, both are complex and expensive solutions. In contrast, this article presents a simple and low cost method to improve tractor positioning when only a GPS receiver is used as the positioning sensor. The method is based on placing the GPS receiver ahead of the tractor, and on applying kinematic laws of tractor movement, or a geometric approximation, to obtain the midpoint position and orientation of the tractor rear axle more precisely. This precision improvement is produced by the fusion of the GPS data with tractor kinematic control laws. Our results reveal that the proposed method effectively reduces the guidance GPS error along a straight trajectory.<\/jats:p>","DOI":"10.3390\/s110605630","type":"journal-article","created":{"date-parts":[[2011,5,26]],"date-time":"2011-05-26T10:58:16Z","timestamp":1306407496000},"page":"5630-5644","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":38,"title":["A Simple Method to Improve Autonomous GPS Positioning for Tractors"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3333-0148","authenticated-orcid":false,"given":"Jaime","family":"Gomez-Gil","sequence":"first","affiliation":[{"name":"Department of Signal Theory, Communications and Telematics Engineering, University of Valladolid, 47011 Valladolid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sergio","family":"Alonso-Garcia","sequence":"additional","affiliation":[{"name":"Department of Signal Theory, Communications and Telematics Engineering, University of Valladolid, 47011 Valladolid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Francisco Javier","family":"G\u00f3mez-Gil","sequence":"additional","affiliation":[{"name":"Department of Electromechanical Engineering, University of Burgos, 09006 Burgos, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tim","family":"Stombaugh","sequence":"additional","affiliation":[{"name":"Biosystems and Agricultural Engineering Department, University of Kentucky, Lexington, KY 40546, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2011,5,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"169","DOI":"10.1016\/S0168-1699(99)00062-9","article-title":"Automatic guidance for agricultural vehicles in Europe","volume":"25","author":"Keicher","year":"2000","journal-title":"Comput. 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