The movable bench cultivation system is a method of increasing area productivity and minimizing the energy needed in a greenhouse. In the system, all plants pass through the same watering point every day. This point should thus be the ideal place to measure precise plant growth information. In this study, we construct an experimental system for a 3D measurement of a community of strawberries cultivated on a 1-meter-long bench. The measurement was made every two to seven days from October 23, 2013 to January 13, 2014. As a result, we obtained 31 images of 10 plant beds. The estimation error of maximum plant height ranged from −30 mm to 32 mm, and that of width ranged from −42 mm to 40 mm. To visualize the growth information effectively, a 2D histogram of the distribution of the 3D points of the plant community was also calculated.
This paper describes the principles of automating the Maitake (Grifola frondosa Dicks. Fr.S. F. Gray) mushroom's cultivation process using the developed speaking mushroom approach (SMA) system. The system measures the bioelectric potential signal from the mushrooms and uses it as a control parameter for the lighting conditions. The purpose of the SMA system is to allow optimal control over the cultivation environment in order to improve the running cost and production yields within mushroom factories. It uses sensors and actuators to maintain the optimal temperature and humidity, and uses the known inherent mushroom bioelectric potential to control the lights. The results from the SMA system in this experiment showed a clear bioelectric potential present in the Maitake fruit body. These bioelectric potential signals reflect the internal rhythm of the mushroom as well as external stimulations. Analysing the measured signals the SMA system demonstrated that it will be possible to save energy and time during mushroom cultivation.
To quickly enhance the productivity of intelligent greenhouses, quality control is needed at agricultural production sites, along with a speaking plant approach to monitor the growth conditions of plants and avoid diseased and underdeveloped plants. We are developing a multi-operation robot equipped with units that contain functions to solve the problem of the instability of environmental factors and subsequent crop yield. Growth-information, pest-detection, and pest-control units were developed for the multi-operation robot and effectively linked to report their actions in order to construct a suitable integrated pest management technology for intelligent greenhouses. The information gathering and various operations were automated by designing each unit to operate autonomously. The system was designed to detect abnormalities by mapping the information provided by the growth-information and pest-detection units. It can then determine the invasion diffusion course of the pest, which makes it easy to take appropriate prophylaxes. Furthermore, the system makes safer working conditions possible because it enables the natural dispersal of ozonated water as a preventive measure. We can expect a further reduction in pesticide consumption by adding a function to disperse a pesticide locally when pests are detected.
The energy costs for artificial lighting in plant factories are very high, but may be decreased by introducing more efficient light sources. Light absorption in plants takes place in the order of a femtosecond, while the chemical reactions for carbon fixation of 5 milliseconds are limiting the processing of photons by the photosystems. In this article, the ShowwxTM scanning laser projector (0.1 W) was tested as an energy-efficient lighting source for cultivating lettuce (Lactuca sativa L. cv. Frillice). This projector uses a mirror where three laser beams are combined and scanned in diverging bi-directional pattern. The average pixel scan time is 20 nanoseconds, while the scanning of the complete projection takes 17 milliseconds. The laser projector was used for artificial lighting of lettuce seedlings (1 week after sowing) and bigger crops (4 weeks after sowing). The light levels were very low (10–20 μmol m−2 s−1) in order to adapt the illumination area of the laser projector to the plant area. A fluorescent lamp (8 W) was used as a reference light source and was mounted on a height, where an equal PPFD was measured at plant height. No differences in relative growth rate were observed in both experiments between the two light sources. A higher final fresh weight was observed for the seedlings illuminated using the scanning laser projector. This particular projector was considered to be not suitable as an artificial light source, but an improved scanning laser projector (with higher laser powers) provides opportunities to improve light efficiency and decrease production costs greatly.
A multi-functioned small scale plant production system was constructed using the speaking plant approach (SPA) as a basis. The optimal plant cultivation environmental conditions have been studied by many researchers, however this report details the experiment and results taken from an automated self-optimizing control system. Unlike the systems used in standard high yield plant factories, this system was designed to determine optimal environmental parameters. Criteria such as air composition, nutrient solution concentration, and lighting conditions were measured and optimized for numerous plant breeds. Through the use of color webcams and sensor data, statistics for many plants were obtained. The measured data was then turned into a profile intended to be used for controlling future growth. Profiling gave the system the unique ability to predetermine the most suitable environmental conditions for each plant. Large scale plant factory running costs are expected to reduce with the use of this profile, scheduling, real time environmental data, and plant growth images. This system also supplied and stored the obtained environmental parameters to a database on a CLOUD server. From the CLOUD server, that information could be offered, in real time, to business associates and other end users.
An ultrasonic pollination device was developed to achieve effective artificial pollination of strawberries in artificial light type plant factories. A phase array of hundreds of ultrasonic transducers was appropriately controlled and focused on one point in space, and it is possible to generate a force at any position in space. The force was modulated at 30 Hz which is the characteristic frequency of strawberry flower. The pollination experiment was conducted using the strawberry variety F1 Elan (Fragaria×ananassa). The total weight of the strawberries harvested over 22 days was 1.22 kg, and the average weights of individual strawberry fruits were 9.1 g.
Recently, plant factory related businesses are increasing because of abnormal climate and natural disasters. Various industries have entered the plant factory business with new cultivating techniques. Various attempts are being made to produce high value crops with research and development of various cultivating techniques. Additionally in the plant factory business, large-scale production, automation and labor-saving are also important for establishing a sustainable industry. Therefore, several techniques have been utilized to improve the use of space, application of automation, and productivity in the plant factory.
This paper describes a newly developed automated plant cultivation system consisting of a simple conveyor robot servicing a multi-shelf rack containing cultivation trays. The robot is situated between two multi-shelf racks, enabling easy access to any tray in any rack. Each multi-shelf rack is divided into sections and each section has artificial lighting at the top and nutrient solution circulated through its cultivation tray. This is a flexible system that has the ability to move plants between any sections in the rack by means of program commands that have been developed specifically for cultivation processes. The cultivation system described here has been operating in the Plant Factory Research Center of Osaka Prefecture University as a novel automated system of lettuce cultivation which requires no manual intervention during its 15-day cultivation process, from seedling planting until harvesting.
Within current plant factories, it is inevitable for people to enter the cultivation rooms. Along with hygiene issues such as prevention from bacteria and contamination, safety consideration for working on the upper level of the shelves are required. Also the labor cost management directly connected with running costs is also an important yet difficult problem to solve. As one way to solve these problem areas such as, hygiene, employee safety, labor cost management, the automatic culture bed transportation system was evaluated. The automated transportation system designed for the contact with the cultivation environment integrates monitoring management with warehouse control system, remote system control, energy saving and cost reduction techniques with shuttle transportation robots driven by brushless motors (24 V). This fabricated system with respect to hygiene, employee safety, and labor cost management was found advantageous compared to conventional plant factories. If employees without automatic machines harvest 5000 plants per day, labor running costs will require 25 to 33 employees working one eight hour day, with a total working time of 200 to 264 h. Furthermore, 63–83 hours out of the total (200–264 hours) is transportation work (31%). The transportation work of 7.8 to 10.4 people out of the 25–33 working one eight h day on 5000 plants per day was witnessed to be automated.