This paper presents the development, testing and validation of SWEEPER, a robot for harvesting sweet pepper fruit in greenhouses. The robotic system includes a six degrees of freedom industrial arm ...equipped with a specially designed end effector, RGB‐D camera, high‐end computer with graphics processing unit, programmable logic controllers, other electronic equipment, and a small container to store harvested fruit. All is mounted on a cart that autonomously drives on pipe rails and concrete floor in the end‐user environment. The overall operation of the harvesting robot is described along with details of the algorithms for fruit detection and localization, grasp pose estimation, and motion control. The main contributions of this paper are the integrated system design and its validation and extensive field testing in a commercial greenhouse for different varieties and growing conditions. A total of 262 fruits were involved in a 4‐week long testing period. The average cycle time to harvest a fruit was 24 s. Logistics took approximately 50% of this time (7.8 s for discharge of fruit and 4.7 s for platform movements). Laboratory experiments have proven that the cycle time can be reduced to 15 s by running the robot manipulator at a higher speed. The harvest success rates were 61% for the best fit crop conditions and 18% in current crop conditions. This reveals the importance of finding the best fit crop conditions and crop varieties for successful robotic harvesting. The SWEEPER robot is the first sweet pepper harvesting robot to demonstrate this kind of performance in a commercial greenhouse.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Crop irrigation uses more than 70% of the world's water, and thus, improving irrigation efficiency is decisive to sustain the food demand from a fast-growing world population. This objective may be ...accomplished by cultivating more water-efficient crop species and/or through the application of efficient irrigation systems, which includes the implementation of a suitable method for precise scheduling. At the farm level, irrigation is generally scheduled based on the grower's experience or on the determination of soil water balance (weather-based method). An alternative approach entails the measurement of soil water status. Expensive and sophisticated root zone sensors (RZS), such as neutron probes, are available for the use of soil and plant scientists, while cheap and practical devices are needed for irrigation management in commercial crops. The paper illustrates the main features of RZS' (for both soil moisture and salinity) marketed for the irrigation industry and discusses how such sensors may be integrated in a wireless network for computer-controlled irrigation and used for innovative irrigation strategies, such as deficit or dual-water irrigation. The paper also consider the main results of recent or current research works conducted by the authors in Tuscany (Italy) on the irrigation management of container-grown ornamental plants, which is an important agricultural sector in Italy.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The world population is continuously increasing. Smart farming is required to keep up with this development by producing more food in a sustainable way. In many new sensor solution developments, the ...results of the sensor itself is at the target, but the whole solution fails to meet the requirements of the agriculture sensing use cases: the developments suffer from singular approaches with a constricted view solely on the sensor, which might be exchangeable. In this article, we present a holistic approach that can help to overcome these challenges. This approach considers the whole use case, from sense, compute, and connect to power. The approach is discussed with the example of the PLANtAR project, where we develop a soil nitrate sensor and a new leaf wetness and microclimate sensor for application in a greenhouse. The resulting sensor is integrated into a sensor node and compared to a state-of-the-art system. The work shows what is needed to assess the best tradeoffs for agriculture use cases based on a horticulture application.
Container hardy ornamental nursery stocks are generally grown with considerable applications of water and agrochemicals, resulting in an important pollution. These crops are often over-irrigated ...because of inaccurate scheduling, which is generally based on growers’ experience. The design of an efficient irrigation management system is therefore crucial to improve profitability and sustainability of production. Reclaimed municipal or industrial wastewater is a source of irrigation water alternative to fresh water; generally, reclaimed wastewater has a high salt content and its use can induce salinity stress in sensitive crops, such as many ornamental species.
In this work, a prototype of fertigation controller was designed for the management of container hardy ornamental nursery stocks irrigated with different water sources, including saline water. The prototype could schedule irrigation, alternatively, as a time clock system, or using a soil moisture dielectric sensor, or by a crop evapotranspiration (ET) model. In addition, the prototype could monitor the salinity in the root zone using either a dielectric sensor capable of measuring both substrate moisture and bulk electrical conductivity (EC), or a probe measuring the EC of the water draining from the containers. Excessive salinization of the containers irrigated with saline water was automatically prevented by the adoption of a series of measures: irrigation with fresh water or a mixture of fresh water and saline water; increase of irrigation dose; reduction of fertilizer concentration in the nutrient solution delivered to the crop. The system was tested in a series of experiments conducted in Pistoia (Italy) between 2008 and 2010 with two ornamental species: Photinia × fraseri Dress and Prunus laurocerasus L. When irrigation with fresh water was scheduled with the dielectric sensor or the ET model, seasonal water use and the loss of both N and P were reduced by 17% to 84% compared with the timer-controlled irrigation. The control of saline water irrigation using either the dielectric sensor or the EC probe mitigated the salinity-induced growth inhibition in both species; however, it did not prevent the occurrence of leaf damages (leaf scorch) on Prunus plants, which were unmarketable at the end of growing season. In contrast, in the more salt-tolerant Photinia plants, the use of the prototype resulted in a fresh water saving of 51% to 73% and all plants were classified in the top market quality category.
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•A controller was designed to irrigate container crops with fresh or saline water.•Substrate salinization was prevented using different sensors and control strategies.•The prototype reduced fresh water use by 17%–84% compared to standard system.•The prototype also decreased the loss of nitrogen and phosphorus by 53%–84%.
The objective of this study was to design and test a prototype fertigation controller for the management of container ornamental nursery stocks irrigated with different water sources, including saline water or reclaimed municipal/industrial wastewater. The prototype could schedule irrigation in various ways, i.e. as a time clock, or by means of a soil moisture dielectric sensor, or using a crop evapotranspiration (ET) model. The prototype also monitored the salinity in the root zone using a dielectric sensor that measured both substrate moisture and electrical conductivity (EC), or a probe measuring the EC of the water draining out of the containers. Excessive substrate salinization of the containers irrigated with saline water (containing 10 mM of sodium chloride) was prevented by the automated adoption of a series of measures: irrigation with fresh water or a mixture of fresh water and saline water; progressive increase of irrigation dose for each event, and progressive reduction of fertilizer concentration in the nutrient solution delivered to the crop. The system was tested in three experiments conducted in Pistoia (Italy) between 2008 and 2010 with two ornamental species: Photinia × fraseri Dress (a salt-medium tolerant species) and Prunus laurocerasus L. (a salt-sensitive species). When irrigation with fresh water was controlled with a dielectric sensor or an ET model, total irrigation water use and the loss of both N and P were reduced by 17% to 84% compared with the time-controlled irrigation. The sensor-based control of saline water irrigation reduced the salinity effects on dry matter accumulation in both species; however, it did not prevent the occurrence of leaf damages (leaf scorch) on Prunus plants, which were unmarketable by the end of growing season. On the contrary, no leaf damages were visible on Photinia plants irrigated with saline and/or fresh water, such that all were classified in the top quality market category. The controller developed in this work could be used in commercial nurseries to improve profitability and sustainability of container hardy ornamental nursery stock production.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The world population is continuously increasing. Smart farming is required to keep up with this development by producing more food in a sustainable way. In many new sensor solution developments, the ...results of the sensor itself is at the target, but the whole solution fails to meet the requirements of the agriculture sensing use cases: the developments suffer from singular approaches with a constricted view solely on the sensor, which might be exchangeable. In this article, we present a holistic approach that can help to overcome these challenges. This approach considers the whole use case, from sense, compute, and connect to power. The approach is discussed with the example of the PLANtAR project, where we develop a soil nitrate sensor and a new leaf wetness and microclimate sensor for application in a greenhouse. The resulting sensor is integrated into a sensor node and compared to a state-of-the-art system. The work shows what is needed to assess the best tradeoffs for agriculture use cases based on a horticulture application.
In Europe, one of the major production centres for hardy ornamental nursery stocks is located around the town of Pistoia in Tuscany, Italy. The map refers to 2004, when nearly 1500 nurseries were in ...operation on about 4600ha. Since then, nursery industry has expanded steadily with an increasing application of container cultivation, which currently covers around 1000ha. Annual water consumption of the whole nursery industry is estimated to be around 12millionm3, which approximates the urban water consumption of Pistoia. Due to over-irrigation, huge quantities of water are being used in nurseries, in particular for container crops that consume 75–80% of the total water demand of HONS industry. Inaccurate scheduling is the main cause of excessive irrigation. Growers generally estimate crop water needs based on personal experience and use simple timers for automated irrigation. The asterisk on the map indicates the Experimental Station for Nursery Crops (Ce.Spe.Vi.), where the irrigation study was conducted. Compared with traditional timer, substrate water status and evapotranspiration irrigation scheduling reduced considerably both water use (−21% to −40%) and nutrient emission (−39% to −74%) in heterogeneous container nursery crops, with no significant effects on plant growth and quality.
•Different irrigation treatments were compared in heterogeneous nursery crops.•Irrigation was controlled using timer, soil moisture probe or crop model.•Water use and nutrient emission were reduced using plant-driven control methods.•Irrigation scheduling did not affect plant growth and quality.
A study was conducted to determine the effects of implementing different irrigation scheduling methods on heterogeneous container hardy ornamental nursery stocks. Four ornamental shrub species were grown in the same irrigation sector during the summer of four consecutive years (2007–2010): Forsythia×intermedia, Photinia×fraseri, Prunus laurocerasus L. and Viburnum tinus L. Automated drip irrigation based on either substrate water status (SW) or calculated crop evapotranspiration (ET; MODEL) was compared with “typical” timer-controlled irrigation (TIMER). In TIMER treatment, containers were irrigated based on grower management. In SW treatment, irrigation was controlled either by a water-filled tensiometer (2007) or by a dielectric soil moisture sensor (2008–2010) placed in one pot with a Prunus plant, the species with intermediate water need as found in preliminary work. In MODEL treatment, irrigation was controlled on the basis of the species with the greatest ET. Crop ET was calculated multiplying reference ET (ET0) by a species-specific crop coefficient (KC), which in turn was estimated from plant height. In all treatments, pre-irrigation substrate water deficit was lower than the plant available water in the container. Compared with TIMER treatment, SW and MODEL irrigation scheduling reduced considerably both water use (−21% to −40%) and nutrient emission (−39% to −74%) with no significant effect on plant growth and quality. Water saving resulted from a reduction of irrigation frequency and leaching fraction (water leached/water applied). Wireless sensor network technology and near/remote monitoring techniques can facilitate the application of plant-driven irrigation scheduling in commercial nurseries, where generally hundreds of plant taxa are cultivated in many independent irrigation sectors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Soil sensor activated irrigation scheduling is used in agriculture to optimally dose water and improve water use efficiency. Soil moisture sensors give point-related information and due to ...heterogeneities in soil hydraulic properties, use of a limited number of sensors may lead to errors in the average soil moisture content obtained for a field. As prices for individual IoT-based soil moisture sensors are still high, there is a need for low-cost soil moisture sensors. The AquaTag prototype is a passive, impedance-based sensor tag and a hand-held readout device for measuring soil water content. It operates contactless using a near-field, narrow-band RF-technology at 27 MHz. The tag has a lower accuracy than regular FD or TDR sensors, but it has the potential to be produced at very low-cost. Growers with small-scale, low-tech soil-grown crop production systems could use it to save water at acceptable cost. The aim of this work was to evaluate performance of prototypes, especially for the effects of production variability, reader-sensor positioning, temperature and soil type calibration. Sensor repeatability was ±0.62% and the overall accuracy tested with well-saturated glass beads was ±10.4%, taking effects of functional calibration, reader positioning and temperature into account. Production variability was improved by functional testing, selection and optimizing the reader signal analysis. Measurements for dry and wet sandy soils are possible at sensor-reader distances up to 10 cm. The reader angular position influences readings only marginally, if measurements are taken with care. Soil temperature affects sensor readings considerably, but the effect of the tag temperature is only marginally. A single calibration curve for two loamy-clay sandy soils was obtained. The AquaTag seems suitable to determine soil moisture content, but in order to reach an accuracy of below ±10%, sensors must be tuned individually, for temperature a compensation is required and in-situ calibration for well-saturated soils is advised. Sensors with a longer shaft are required to use the tag for measurements at common crop rooting depths.
A new passive sensor for remote measurement of water content in sandy soil was designed, using a surface acoustic wave (SAW) reflective delay line. Information from this sensor can be obtained by an ...interrogation device via a radio link operating in the European 434-MHz industrial-scientific-medical band. The SAW device, manufactured on the YZ cut of LiNbO/sub 3/, is mounted and sealed in a standard dual inline 16 package and contains four electroacoustic transducers. One transducer is connected to an external antenna to pick up an RF request signal from the interrogation device and to send back an RF response. The second transducer operates as a reflector. The bus bars of this transducer are connected with two measuring rods through an electrical transmission line. These rods can be inserted into sandy soil. The final two transducers operate as reflectors and are included for reference purposes. The transmission line and the two rods spanning the sand-water mixture have a characteristic impedance Z/sub load/, which loads the second transducer. Changes in the soil water content are observed as a change of the total permittivity due to the high permittivity of free water, which, in turn, affects Z/sub load/, as well. The amplitude and phase of the acoustic reflection at the second transducer changes due to a variation of the terminating Z/sub load/. This then results in a difference in attenuation and phase of the corresponding peak in the time domain. Thus, the RF response of the sensor carries information about the water content between the rods, which, therefore, can be detected by and evaluated in the interrogation unit.
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