Authors: Farkas, I.

Abstract: Monitoring of greenhouse plants gives a straight diagnosis on their health and wellness. A computer vision method was investigated for detection and localization of leaves' wilting as a sign of visual appearance. Tomato, cucumber and paprika were tested using side projected canopy images. The camera was focused on the plant canopy from horizontal direction in order to obtain images covering the leaves. At defined time scales images were taken to analyze leaf and stem movements as the visual signs of plant state. The machine based control can be applied successfully in crop irrigation. The parameters of the control unit were identified and adjusted in each case of the plant, as well.

Keywords: plant wellness,leaf inclination,image analysis,water stress,wilting,automation,monitoring

Digital Object Identifier (DOI): 10.3182/20101206-3-JP-3009.00051

Conference: Third IFAC International Conference Agricontrol (2010)

Location: , Japan

Start Date: Mon Dec 06 2010 - End Date: Wed Dec 08 2010

Page Numbers: 289-293

Authors: Saito, Yuta; Shimizu, Hiroshi; Nakashima, Hiroshi; Miyasaka, Juro; Ohdoi, Katsuaki

Abstract: Plant factory is a plant production system with controlled temperature, carbon dioxide concentration and light environment to enhance plant growth efficiently. Fluorescent lamp is popularly used in a plant factory, however, the spectrum of fluorescent light is broad and some portion of them is not necessary for photosynthesis. On the other hand, LED (light emitting diode) has narrow band width and is getting easy to use these days. The final goal of this project is to develop a new light apparatus with LEDs for plant factory. The specific objective is to investigate the effective light quality for growing plant more rapidly. The effect of light generated by monochromic and mixed radiation from LEDs (blue, green, red) on the response of lettuce (Lactuca sativa L.) were evaluated and compared with the effect of lettuce irradiated by fluorescent lamps. Photosynthesis rate of lettuce increased in monochromic red light and the light mixed with red and blue light. Number of leaves decreased in monochromic blue light. Fresh weight of lettuce was increased in monochromic red and fluorescent light, but monochromic red light significantly decreased dry weight rate. In the view of energy saving, LED is much better than fluorescent lamp. Especially, red LED is good.

Keywords: plant factory,light quality,carbon dioxide concentration,light intensity,morphogenesis,fresh weight,LED

Digital Object Identifier (DOI): 10.3182/20101206-3-JP-3009.00052

Conference: Third IFAC International Conference Agricontrol (2010)

Location: , Japan

Start Date: Mon Dec 06 2010 - End Date: Wed Dec 08 2010

Page Numbers: 294-298

Authors: Van Straten, G.; Slegers, P. M.; Van Willigenburg, L. G.; Bosma, R.; Van Boxtel, A. J. B.; Wijffels, R. H.

Abstract: The cultivation of algae in photo-bioreactors shows similarities to crop cultivation in greenhouses, especially when the reactors are driven by sun light. Advanced methodologies for dynamic optimization and optimal control for greenhouses are known from earlier research. The aim here is to extend these methodologies to microalgae cultivated in a flat plate photo-bioreactor. A one-state space model for the algal biomass in the reactor is presented. The growth rate vs. light curve is parameterized on the basis of experimental evidence. Spatial distribution of light and growth rate between the plates is also considered. The control variable is the dilution rate. Dynamic optimal control trajectories are presented for various choices of goal function and external solar irradiation trajectories over a horizon of 3 days. It was found that the algae present in the reactor at final time represent a value for the future. Numerical and theoretical results suggest that the control is bang-(singular-)bang, with a strong dependence on the weather. The optimal biomass also depends on the available light, and achieving it to reach a new optimal steady cycle after a prolonged change in weather may take several days. A preliminary theoretical analysis suggests a control law that maximizes the effective growth rate. The analysis shows that like in the greenhouse case, the co-state of the algal biomass plays a pivot role in developing on-line controllers.

Keywords: optimal control,photo-bioreactor,microalgae,dynamic optimization,state-space model,bang-bang control

Digital Object Identifier (DOI): 10.3182/20101206-3-JP-3009.00053

Conference: Third IFAC International Conference Agricontrol (2010)

Location: , Japan

Start Date: Mon Dec 06 2010 - End Date: Wed Dec 08 2010

Page Numbers: 299-303

Authors: Van Ooteghem, Rachel J. C.

Abstract: An optimal climate control has been designed for a solar greenhouse to achieve optimal crop production with sustainable instead of fossil energy. The solar greenhouse extends a conventional greenhouse with an improved roof cover, ventilation with heat recovery, a heat pump, a heat exchanger and an aquifer. It was found that in the optimal controlled solar greenhouse, gas use can be seriously reduced (by 52%), while the crop production is significantly increased (by 39%), as compared to an optimal controlled conventional greenhouse without the solar greenhouse elements.

Keywords: horticulture,greenhouse,solar greenhouse,optimal control

Digital Object Identifier (DOI): 10.3182/20101206-3-JP-3009.00054

Conference: Third IFAC International Conference Agricontrol (2010)

Location: , Japan

Start Date: Mon Dec 06 2010 - End Date: Wed Dec 08 2010

Page Numbers: 304-309

Authors: Yin, Xiang; Lu, Boyon

Abstract: A new method is proposed and discussed in this paper, based on Virtual Prototyping Technology. The aim is to test the wheel-type tractor slippage which is an important index to indicate whether the engine power is fully converted by the wheels into the traction applied to the implements. A 3D model of an existing two-wheel drive tractor (SH500) is constructed in the 3D design software Pro/Engineer and exported out into the virtual prototyping software ADAMS in which the slippage virtual test system is established and the slippage virtual test is carried out. For a general purpose, the virtual system is parameterized so that the parameters as system inputs to define work conditions could be modified by users in terms of specific environment. To verify its feasibility and validation, the virtual test system is set up to work under two given conditions. Results show that the slippage remains almost the same at constant traction, whose averages are 10.36% and 16.69% at 5.4kN and 9.8kN, respectively. So, this means that it is possible to construct a virtual system to acquire the slippage without the necessity of a physical test system and field experiment which are both costly and time-consuming.

Keywords: tractor,slippage,virtual system,virtual test

Digital Object Identifier (DOI): 10.3182/20101206-3-JP-3009.00055

Conference: Third IFAC International Conference Agricontrol (2010)

Location: , Japan

Start Date: Mon Dec 06 2010 - End Date: Wed Dec 08 2010

Page Numbers: 310-315

Authors: Mori, Ryoichi; Ohdoi, Katsuaki; Shimizu, Hiroshi; Nakashima, Hiroshi; Miyasaka, Juro

Abstract: Biogas from methane fermentation is anticipated for use as an alternative energy resource to fossil fuel. However, a problem persists related to treatment of wastewater generated in methane fermenters. Consequently, the wastewater must be processed additionally to reduce environmental load when released. The most important problem is the treatment raises the total running cost of fermenters. To lower this cost, application of the wastewater as liquid fertilizer in paddy fields without the treatment has been studied. However, in rice cropping, the suitable periods for application are limited. This study is intended to produce models for estimating working hours in each paddy field to construct an effective operation plan of a slurry injector for liquid fertilizer. Working times in the paddy fields were investigated for two cases of liquid fertilizer application: Nantan and Yamaga. Two simple models can be constructed; which model should be used can be determined according to the paddy field shape.

Keywords: methane fermentation,liquid fertilizer,working hours,modeling,statistics

Digital Object Identifier (DOI): 10.3182/20101206-3-JP-3009.00056

Conference: Third IFAC International Conference Agricontrol (2010)

Location: , Japan

Start Date: Mon Dec 06 2010 - End Date: Wed Dec 08 2010

Page Numbers: 316-321