{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,27]],"date-time":"2026-01-27T23:11:51Z","timestamp":1769555511182,"version":"3.49.0"},"reference-count":33,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2011,2,28]],"date-time":"2011-02-28T00:00:00Z","timestamp":1298851200000},"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>Electronic canopy characterization is an important issue in tree crop management. Ultrasonic and optical sensors are the most used for this purpose. The objective of this work was to assess the performance of an ultrasonic sensor under laboratory and field conditions in order to provide reliable estimations of distance measurements to apple tree canopies. To this purpose, a methodology has been designed to analyze sensor performance in relation to foliage ranging and to interferences with adjacent sensors when working simultaneously. Results show that the average error in distance measurement using the ultrasonic sensor in laboratory conditions is \u00b10.53 cm. However, the increase of variability in field conditions reduces the accuracy of this kind of sensors when estimating distances to canopies. The average error in such situations is \u00b15.11 cm. When analyzing interferences of adjacent sensors 30 cm apart, the average error is \u00b117.46 cm. When sensors are separated 60 cm, the average error is \u00b19.29 cm. The ultrasonic sensor tested has been proven to be suitable to estimate distances to the canopy in field conditions when sensors are 60 cm apart or more and could, therefore, be used in a system to estimate structural canopy parameters in precision horticulture.<\/jats:p>","DOI":"10.3390\/s110302459","type":"journal-article","created":{"date-parts":[[2011,3,1]],"date-time":"2011-03-01T15:44:36Z","timestamp":1298994276000},"page":"2459-2477","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":67,"title":["Performance of an Ultrasonic Ranging Sensor in Apple Tree Canopies"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9775-5471","authenticated-orcid":false,"given":"Alexandre","family":"Escol\u00e0","sequence":"first","affiliation":[{"name":"Department of Agro-Forestry Engineering, University of Lleida, Av. Rovira Roure, 191. 25198 Lleida, Catalonia, Spain"}]},{"given":"Santiago","family":"Planas","sequence":"additional","affiliation":[{"name":"Department of Agro-Forestry Engineering, University of Lleida, Av. Rovira Roure, 191. 25198 Lleida, Catalonia, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6746-2830","authenticated-orcid":false,"given":"Joan Ramon","family":"Rosell","sequence":"additional","affiliation":[{"name":"Department of Agro-Forestry Engineering, University of Lleida, Av. Rovira Roure, 191. 25198 Lleida, Catalonia, Spain"}]},{"given":"Jes\u00fas","family":"Pomar","sequence":"additional","affiliation":[{"name":"Department of Agro-Forestry Engineering, University of Lleida, Av. Rovira Roure, 191. 25198 Lleida, Catalonia, Spain"}]},{"given":"Ferran","family":"Camp","sequence":"additional","affiliation":[{"name":"Department of Agriculture, Livestock, Fisheries, Food and Environment, Center of Agricultural Mechanization, Generalitat de Catalunya, Av. Rovira Roure, 191. 25198 Lleida, Catalonia, Spain"}]},{"given":"Francesc","family":"Solanelles","sequence":"additional","affiliation":[{"name":"Department of Agriculture, Livestock, Fisheries, Food and Environment, Center of Agricultural Mechanization, Generalitat de Catalunya, Av. Rovira Roure, 191. 25198 Lleida, Catalonia, Spain"}]},{"given":"Felip","family":"Gracia","sequence":"additional","affiliation":[{"name":"Department of Agriculture, Livestock, Fisheries, Food and Environment, Center of Agricultural Mechanization, Generalitat de Catalunya, Av. Rovira Roure, 191. 25198 Lleida, Catalonia, Spain"}]},{"given":"Jordi","family":"Llorens","sequence":"additional","affiliation":[{"name":"Department of Agro-Food and Biotechnology Engineering, Polithecnical University of Catalonia, Av. Canal ol\u00edmpic, 15. 08860 Castelldefels, Catalonia, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3929-5649","authenticated-orcid":false,"given":"Emilio","family":"Gil","sequence":"additional","affiliation":[{"name":"Department of Agro-Food and Biotechnology Engineering, Polithecnical University of Catalonia, Av. Canal ol\u00edmpic, 15. 08860 Castelldefels, Catalonia, Spain"}]}],"member":"1968","published-online":{"date-parts":[[2011,2,28]]},"reference":[{"key":"ref_1","first-page":"64","article-title":"Gallons per acre of sprayed area an alternative standard term for the spraying of plantation crops","volume":"16","author":"Morgan","year":"1964","journal-title":"World Crop"},{"key":"ref_2","first-page":"19","article-title":"Base gallonage per acre","volume":"60","author":"Byers","year":"1971","journal-title":"Virginia Fruit"},{"key":"ref_3","first-page":"85","article-title":"Electronic measurement of tree row volume","volume":"1","author":"McConnell","year":"1983","journal-title":"Agr. Electron"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"264","DOI":"10.13031\/2013.30698","article-title":"Electronic measurement of tree canopy volume","volume":"31","author":"Giles","year":"1988","journal-title":"Trans. ASABE"},{"key":"ref_5","unstructured":"Roper, BE (1988). Grove Sprayer, U.S. Patent 4,768,713,."},{"key":"ref_6","unstructured":"Giles, DK, Delwiche, MJ, and Dodd, RB (1989). Method and Apparatus for Target Plant Foliage Sensing and Mapping and Related Materials Application Control, U.S. Patent 4,823,268,."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1636","DOI":"10.13031\/2013.30614","article-title":"Control of orchard spraying based on electronic sensing of target characteristics","volume":"30","author":"Giles","year":"1987","journal-title":"Trans ASABE"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"271","DOI":"10.1016\/S0021-8634(89)80024-1","article-title":"Sprayer control by sensing orchard crop characteristics: Orchard architecture and spray liquid savings","volume":"43","author":"Giles","year":"1989","journal-title":"J. Agr. Eng. Res"},{"key":"ref_9","unstructured":"Stafford, JV (, January September). An automatic spray control for airblast sprayers: First results. Preciscion Agriculture \u201997, Warwick, UK."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"545","DOI":"10.1016\/j.cropro.2007.08.012","article-title":"Targeted spray technology to reduce pesticide in runoff from dormant orchards","volume":"27","author":"Brown","year":"2008","journal-title":"Crop Prot"},{"key":"ref_11","first-page":"379","article-title":"Design and testing of an automatic machine for spraying at a constant distance from the tree canopy","volume":"77","year":"2000","journal-title":"J. Agr. Eng. Res"},{"key":"ref_12","first-page":"35","article-title":"Pesticide loss reduction by automatic adaptation of spraying on globular trees","volume":"78","year":"2001","journal-title":"J. Agr. Eng. Res"},{"key":"ref_13","unstructured":"Escol\u00e0, A, Solanelles, F, Planas, S, and Rosell, JR (, January July). Electronic control system for proportional spray application to the canopy volume in tree crops. Budapest, Hungary."},{"key":"ref_14","first-page":"139","article-title":"Spray application efficiency of an electronic control system for propotyional application to the canopy volume","volume":"66","author":"Solanelles","year":"2002","journal-title":"AAB J"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"473","DOI":"10.1016\/j.biosystemseng.2006.08.004","article-title":"An electronic control system for pesticide application proportional to the canopy width of tree crops","volume":"95","author":"Solanelles","year":"2006","journal-title":"Biosyst. Eng"},{"key":"ref_16","unstructured":"Stafford, JV (, January June). Variable dose rate sprayer prototype for tree crops based on sensor measured canopy characteristics. Precision Agriculture \u201907, Skiathos, Gr\u00e8cia."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1287","DOI":"10.1016\/j.cropro.2006.11.003","article-title":"Variable rate application of plant protection products in vineyard using ultrasonic sensors","volume":"26","author":"Gil","year":"2007","journal-title":"Crop Prot"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"239","DOI":"10.1016\/j.cropro.2009.12.022","article-title":"Variable rate dosing in precision viticulture: Use of electronic devices to improve application efficiency","volume":"29","author":"Llorens","year":"2010","journal-title":"Crop Prot"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"367","DOI":"10.13031\/2013.8587","article-title":"Investigation of laser and ultrasonic ranging sensors for measurements of citrus canopy volume","volume":"18","author":"Tumbo","year":"2002","journal-title":"Appl. Eng. Agric"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"173","DOI":"10.13031\/2013.15887","article-title":"Effects of foliage density and ground speed on ultrasonic measurement of citrus tree volume","volume":"20","author":"Zaman","year":"2004","journal-title":"Appl. Eng. Agric"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1016\/j.compag.2004.10.002","article-title":"Software development for real-time ultrasonic mapping of tree canopy size","volume":"47","author":"Schumann","year":"2005","journal-title":"Comput. Electron. Agric"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"467","DOI":"10.1007\/s11119-005-4243-x","article-title":"Performance of an ultrasonic tree volume measurement system in commercial citrus groves","volume":"6","author":"Zaman","year":"2005","journal-title":"Precis. Agric"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"331","DOI":"10.13031\/2013.18448","article-title":"Variable rate nitrogen application in florida citrus based on ultrasonically-sensed tree size","volume":"21","author":"Zaman","year":"2005","journal-title":"Appl. Eng. Agric"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"19","DOI":"10.13031\/2013.20183","article-title":"Variable rate granular fertilization of citrus groves: Spreader performance with single-tree prescription zones","volume":"22","author":"Schumann","year":"2006","journal-title":"Appl. Eng. Agric"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"39","DOI":"10.13031\/2013.20186","article-title":"Estimation of citrus fruit yield using ultrasonically-sensed tree size","volume":"22","author":"Zaman","year":"2006","journal-title":"Appl. Eng. Agric"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1505","DOI":"10.1016\/j.agrformet.2009.04.008","article-title":"Obtaining the three-dimensional structure of tree orchards from remote 2D terrestrial LIDAR scanning","volume":"149","author":"Rosell","year":"2009","journal-title":"Agric. Forest Meteorol"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"128","DOI":"10.1016\/j.biosystemseng.2008.10.009","article-title":"A tractor-mounted scanning LIDAR for the non-destructive measurement of vegetative volume and surface area of tree-row plantations: A comparison with conventional destructive measurements","volume":"102","author":"Rosell","year":"2009","journal-title":"Biosyst. Eng"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"van Henten, EJ, Goense, D, and Lokhorst, C (2009). Precision Agriculture \u201909, Wageningen Academic Publishers.","DOI":"10.3920\/978-90-8686-664-9"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1420","DOI":"10.1016\/j.agrformet.2010.07.005","article-title":"Sensitivity of tree volume measurement to trajectory errors from a terrestrial LIDAR scanner","volume":"150","author":"Sanz","year":"2010","journal-title":"Agric. Forest Meteorol"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1007\/s11119-005-6789-z","article-title":"Nutrient management zones for citrus based on variation in soil properties and tree performance","volume":"7","author":"Zaman","year":"2006","journal-title":"Precis. Agric"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Mann, KK, Schumann, AW, and Obreza, TA (2010). Delineating productivity zones in a citrus grove using citrus production, tree growth and temporally stable soil data. Precis Agric.","DOI":"10.1007\/s11119-010-9189-y"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"449","DOI":"10.13031\/2013.23479","article-title":"Quantifying sources of error in ultrasonic measurements of citrus orchards","volume":"23","author":"Zaman","year":"2007","journal-title":"Appl. Eng. Agric"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"213","DOI":"10.1016\/j.compag.2010.11.007","article-title":"Evaluation of ultrasonic sensor for variable-rate spray applications","volume":"75","author":"Jeon","year":"2011","journal-title":"Comput. Electron. 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