SAS_EN - A Swarm of Agents for a Sustainable Environment Ruvindee Rupasinghe, Sanjaya Ratnayake, Anuruddha Ranatunga, Amila Sajayahan, Asoka S. Karunananda Faculty of nformation technology, University of MoratuwaAbstract: sustainability. It is evident that environmental Environment consists of heterogeneous entities sustainability cannot be ensured as individual entities, yetwhich are working collaboratively to keep the environment needs corporation from heterogeneous entities/agentssustainable. The general concept of “environmental which have diverse interests, and physically distributed insustainability” refers to the necessary balance betweenhuman wants and needs and the capacity of the natural much lactation and also operate under different conditions.systems of the earth. Thus to keep the balance of environment For instance, collaboration among entities that emitsthe communication among photosynthesis, co2 emission, carbon dioxide, executes photosynthesis and releasesenvironmental conditions, nutrient conditions and nutrient oxygen must be communicating each other for ensuringdeficiencies of the plant are important. Nevertheless it has sustainability in the environment. Obviously, if the entitybecome a major issue in maintaining those conditions within responsible for emission of Co2 can be communicated witha controlled environment. the entity for photosynthesis and increases the rate of Therefore the communication among resource photosynthesis, level of Co2 can be reduced. In order toentities that are involved in a certain task of the environment increase the rate of photosynthesis, the plant as an entityand reaching consensus for protecting and ensuring thesustainability of a given environment is highly important. requires a higher level of nutrients . As such theThus project implements SAS_EN, which collaboratively photosynthesis entity cannot increase it processing withoutworks for a sustainable environment in a Hydroponics the consent from the plant. Therefore, we identifyGreenhouse environment. environmental sustainability as a distributed problem The system has been implemented using agent involving many entities/agents. In this sense, any humantechnology. There are distinct agents dedicated for each tasks activity such as cultivation, industries, urbanization andof the environmental sustainability and they collaboratively even housing in the environment must be concerned withwork together to achieve a common goal. Hydroponics, which at least three aspects. Those are space/location utilization,grows in a controlled environment, has been used for testingand evaluating the solution. The test results have shown its environmental resource as the input to the activity and thepotential of using SAS_EN for solving the distributed emission of waste products to the environment.problems of the environment. Thus the project identifies the environmental sustainability as a collaboration of many entities in the I. INTRODUCTION environment and identifies an agent based solution is the Natural environment has been the infrastructure most appropriate way to maintain the balance of thefor all activities of living beings in the world. As such all environment . It consists of four agents namely plantliving beings occupy and consume environmental agent, ventilation agent, humidity agent and nutrient agent.resources while releasing the waste products to the same Hydroponics environment have been used as the testenvironment . Undoubtedly, environment is the most environment for implementing the solution. The externalprecise resource to be effetely utilized and managed. environmental factors and concentration of water medium Nevertheless when compare with other living is controlled and monitored in order to achieve thebeings, humans release harmful waste products to the maximum yield from the plantation.environment as a part of their consumption of Rest of the paper is organized as follows. Theenvironmental resources . In one sense, environment section two depicts the existing approaches of balancingspace has been utilized by the man kind by destroying the the environmental sustainability while section three depictsnatural balance created by the existence of other living the adopted approach of using a multi agent system for thebeings. On the other hand, humans consume limited environmental sustainability. The section four describesenvironment resources without allowing regeneration of the design and the section five is about the implementationsuch resources through natural cyclic process [11, 14, 6]. approach. The section six is about user scenarios and theFor instance, level of carbon dioxide due to industries can features of the system. The paper finally deals with thebe reduced and pump oxygen in to the environment evaluation and further works.through process of photosynthesis in plants . However, despite the ever increasing II. EXSISTING APPROACHEStechnological advancements in the modern world, the use Currently there are several existing approaches forof the modern technology for ensuring a sustainable controlling and monitoring the environment. Some of theseenvironment is very limited. Therefore, SAS_EN intends existing approaches include grow rooms; grow boxes andto provide a technological solution for environment automation of individual components. Further
environmental management systems and environmental source products which attempt to automate a hydroponicsinformation systems also have been implemented. environment. Hmeter project is one such approach . A. Environmental information systems When consider all these approaches, common thing is that The high availability and variety of large each of them tries to bring some kind of automation in toenvironmental data sets have open new opportunities for the environment. However, all of them follow a reactivedata mining and useful cross-referencing of disparate paradigm, where the system waits till the environmentenvironmental data sets. Taking the advantage of these change for making any action. Anyway, if the automationopportunities, environmental information systems will system could act pro-actively, it will be a much efficientneed to operate effectively in a distributed, open system compared to their reactive counterparts. Especially,environment. The paper describes the New Zealand since the environmental changes are unpredictable andDistributed Information System (NZDIS) software happens so dynamically, whatever the system whicharchitecture for environmental information systems. It controls the environment should be intelligent and flexibleoptimizes extensibility, openness, and flexible query enough to adopt the system accordingly in quick time.processing, by using collaborating software agents that However, existing reactive paradigm is not good enoughcommunicate by means of a standard declarative agent for this purpose.communication language. The metadata of environmental III. SAS_ENdata sources are stored as part of agent ontologies, which In addressing the distributed problem of environmentalrepresent information models of the domain of the data sustainability, we propose to use the Modern Agentrepository. The agents and ontological framework are Technology. The intelligent agents represent one of thedesigned as much as possible to take advantage of standard promising technologies for building complex softwareobject-oriented technology, such as CORBA, UML, and systems . Multi-agent systems (MASs) are systemsOQL, in order to enhance the openness and accessibility of composed by at least two autonomous agents that are ablethe system . to interact with one another. The agents may have a global goal to solve, or B. Grow rooms they may have their own goals to pursue . The agent-A grows room, is a room of any size where plants are based approach could be applied with success in thegrown under controlled conditions (Source: Wikipedia). In environmental management . As such we intend togrow rooms, artificial light is used mostly. Here, these develop a several autonomous Agents that are responsibleartificial light sources could come from three main types. for different aspects of a given environment therebyThose are, the high intensity discharge lamps, compact forming a Multi Agent System for ensuring environmentfluorescent lamps and traditional fluorescent lamps. Since sustainability. Since a controlled environment wasthese artificial lighting sources could generate a lots of necessary for implementing the solution hydroponics, theheat, there should be a proper ventilation system installed technology of growing plants on a nutrient solution thatfor the grow room. Otherwise there is a possibility of supply all nutrient elements needed for optimum plantoverheating the room and the over consuming of theessential resources like Oxygen and Carbon Dioxide. C. Grow boxesGrow boxes are a smaller version of grow room which ismostly used for domestic plantations. Here, a grow box is aself contained environment for growing any kind of a plantthat could be grown hydroponically. Since this is a totallyenclosed environment fans have to be used for intake andexhausting air from the system. Apart from that there willbe odor controlling systems and air conditioning systemsfor the better management of the plant environment. Growboxes are highly useful when you are not having patch ofland for growing plant or living in an urban Flats. D. Automation componentsThere are a number of automation products available in themarket for automating various aspects of a hydroponicsenvironment. These products include nutrient dosingequipments, remote automation systems, wireless camerasdesigned for hydroponics environments, automated watersensors and pumps etc. Also there are few other open Fig 1: Top level architecture of SAS_EN
growth, in a greenhouse environment was used [4, 3]. The SAS_EN mainly uses four sensors to collect waternutrient solution of the plantation is the basis for all level, Fertilizer level, EC and PH value. Each sensorhydroponics systems. This contains all the mineral control takes the input signals and then sends to the ebox.elements needed for the growth of the plant. After getting the sensor data, Logical unit is responsible to control MCU and electric valve system which controls the IV. DESIGN above mentioned levels. All the control units are The system consists of four agents namely Plant implemented within the hydroponics box (Figure 2). Theagent, humidity agent, ventilation agent and nutrient agent. implementation details of the SAS_EN control units areEvery agent communicates with other agents to keep the described below.green house environment balanced. When the temperaturegoes up, the humidity agent notifies it to the ventilation Water level controlling Unitagent and then the ventilation agent reduces the ventilationso that the humidity can goes up. Mean time the humidity The water level sensor and the water pump control areagent can increase the humidity by increasing the kept inside the Hydroponics box and it measures the waterevaporation in the environment. Thus through the level of the hydroponic solution. The water pump controlcommunication between all the agents the environmental unit consists of electric valves which are controlled by theconditions are kept balanced. ebox. When the water level changes it directly sends the The figure 1 depicts the top level architecture of control signals to the logical unit and the logical unitthe system with the micro controller units (MCU), sensors, processes the water level with the given log file data andagents and the ebox. The Agents are developed with a little using MCU unit and automatically controls the water levelknowledge base and ability communicate with appropriate by adding water to the Hydroponics box. Every time theAgents and also able to send signals coming from Ebox to system is responsible to keep water level in requiredcontrol devices such as ventilation fans and lights. The maximum level. After reaching to the maximum waterfeatures and the responsibilities of the agents and otherconnected devices are as follows. The plant agent is responsible for identifying theabnormalities in the plant and the nutrient deficiencies.The color changes happen in the leaves and theabnormalities of the nuts and the disorders in harvest canbe identified by the plant agent. Thus with theidentification of the deficiencies the plant agent cancommunicate with nutrient agent and other relevantentities to solve the issues in the plant. The Nutrient agent is responsible for controllingthe nutrient conditions of the plant. Thus it is able tocontrol the EC (Electric Conductivity), PH and nutrientconcentrations of the hydroponics solution. It controls theconcentration of the solution by adding water and Albertsolution. The ventilation of the atmosphere is also animportant factor for a successful growth of a plant.Therefore the ventilation agent controls the ventilationstates in the greenhouse. Thus it controls the air flow Fig 2: the architecture of hydroponics boxwithin the green house environment. it controls theventilation conditions of the plantation using the level the water level sensor sends control signals to ebox.ventilation fan. Then it closes the electric water pumping valve. The Humidity agent controls the humidity andtemperature states of the greenhouse. The humidity agent Air pumping Unitand the ventilation agent maintain a direct communication Air pumping which is controlled by the ebox is anotherbetween themselves in order to balance the atmosphere of special feature of SAS_EN. Normally it is pumping the airthe green house. When the humidity increases in the green periodically. The time is controlled by the ebox accordinghouse environment, the ventilation agent gets activated and to the conditions of the plant and the water medium. Inincreases the air flow of the greenhouse. Thus the addition to that the air pumping unit supports to mix theventilation and humidity agent work conversely to balance fertilizer around the hydroponics box. Whenever thethe environmental conditions of the greenhouse. fertilizer is added to the water medium the air pumping unit automatically starts and mix up the hydroponics V. IMPLEMENTATION
culture. The suitable time to add fertilizers and to start thepumping is decided by the Plant Agent. A. Features of SAS_EN The agents inherit the common features of software agents.EC and PH level controlling Unit: They have specific behaviors to handle various atmospheric conditions. Among others, following are the The Albert solution is used as the main fertilizer for major features of SAS_EN.the hydroponic solution. Thus the EC and PH levels System has autonomous monitoring and controlchange according to the fertilizer level. In this case we because agents operate with little or no intervention fromshould get those three inputs together to control each other. users, and apply control strategies accordingly. ForThe current condition of the hydroponic medium is sent to instance, if the greenhouse is used in tropical environment,the Nutrient agent and it processes each value together. natural ventilation will be heavily used, without operatingTherefore the concentration of the solution is controlled by exhaust fans.monitoring the time of water valve open. The Nutrient Agents are necessarily able to communicate to shareagent periodically checks the EC and PH level and if there knowledge and cooperate in solving problems. Foris a change compared to the ontology then the fertilizer instance, on the request of Humidity Agent, the Ventilationvalves open for relevant time period. The concentration of Agent may want to operate fast, but Nutrient Agent’sthe water medium is checked periodically to check the concern about water level must be negotiated first. It isimbalances of the solution. Further the pH levels in the able to reach consents to increase utility. For example,solution are controlled by adding suitable amount of Plant Agent wants to increase the duration ofdiluted acids. Thus the nutrient agent directly photosynthesis to get a target high yield, and may requestcommunicates with the MCU then MCU controls the Light Sensor Agent to release light for a longer period .valves. Collaboration among Agents is a means of reducing workload of a single Agent. For instance,Data analyze of Logical Unit: Humidity Agent can assist to reduce work load of Logical Unit gets inputs from the sensor unit and Ventilation Agent, if the intensity of light is reduced in theprocess those using data stored in ontology. Then Logical green house.unit gives control signals to MCU to control each levels of Agents can work on the basis of previousthe Hydroponics box. The agents periodically experiences stored in the database, without solving similarcommunicate with each other to analyze the conditions of problems from the scratch. Agents can also adapt tothe green house environment. situations, which are not experienced before. Parameters required to grow different plants at different environmental Further the reporting module of SAS_EN provides a conditions can be learned by the Agents.daily report indicating the daily conditions of the It should be noted that the SAS_EN comprisesplantations and how SAS_EN has reacted to them. And Agent that are responsible for monitor and controlalso through the SAS_EN log it can derive to certain environmental parameters such as Temperature, Humidity,conclusions and provide custom reports. Ebox works as the Ventilation, Water, Nutrients, etc. The Agents developedcentral processor and the communication medium between for this purpose can be used for modeling a sustainableeach Agent in the greenhouse and the PDA and takes up environment under given condition.the task of information analysis, controlling and decisionmaking. VII. TESTING AND EVALUATION Light Sensor Agent controls the light intensity of thegreenhouse. Micro control unit (MCU) works as the The system was tested in a hydroponics plantation. TheBluetooth controller and sensor data collator and receiver. plants were grown in the water which was controlled by the SAS_EN hydroponics box. The box was able to keep VI. USER SCENARIOS AND THE FEATURES OF the required conditions of the solution continuously. We SAS_EN tested the system for a week and after a week’s period the plantation was healthy and looked good. The main users of SAS_EN are farmers and thegardeners. The farmers can get the real time control TABLE 1: WAY SAS_EN REACT TO VARIOUS CONDITIONSenvironment details through the web application provided. Scenario Result CommentsFurther if required, farmer can give instructions to change Reduce the water Increase the water level solved Goodthe conditions and also pre program certain conditions. levelThey are given the capability of viewing the data receivedfrom each agent, current conditions of the Hydroponics Deactivated Light Communicated fine OK sensorgreenhouse environment and giving orders to the system. Further the Researchers are given the capability of Raining Heavily OK OKviewing the statistical records on the Hydroponicsgreenhouse environment through the internet. Reduction of pH It was increased Ok level
Test Environment Survey results The test environment was a hydroponics plantation in Also a survey was conducted to analyze the effectiveness a home garden. The plants were grown in the water which of the system. Ultimate objective of the project is to was controlled by our hydroponics box. In order to ensure generate a maximum yield using minimum resources. In that the system is working properly, both component order to test the system we used a same farm with two testing and system testing was undertaken. nurseries where one is managed with embedded system and other one is managed manually. We obtained In the first scenario we reduce the water level and following performance analysis from the farmers (Table switch on the system. System identified that and pore the 2).Also table 3 depicts the live deployment results. Even water up to the required level. Similar tests were conducted though, above mention functions has taken nearly 10 min to ensure component testing. So we reduce the light, for 20 m2 plantation there is no liner relationship between change EC / PH, change nutrient level. The results time and area. The radiant reduces when area increases. obtained during each scenario are depicted in table 1. VI. CONCLUSION The system was specially designed as an embedded system It is evident that use of the technology for because in some plantations user frequent visits are rare. In environmental sustainability must have a mechanism for order to simulate those situations the system was sensing the environmental parameters and response continuously run for a week. Mean while when the accordingly. Therefore the system needed an autonomous conditions were changed the Application reacted to those monitoring and control environment. Thus software agents were able to provide this capability for SAS_EN to behaveTABLE 2: THE RESULTS OBTAINED FROM FIVE FARMERS in different environmental conditions.Performance Managed by the Managed manually SAS_EN can be implemented as an embeddedevaluation embedded solution application and it has already shown its potential to solvecriteria distributed problems. The SAS_EN can be customized toYield Yield was high. Also Yield is average. There any application involving environmental parameters cost there were only few were many perishable effectively. In future, we expect to enhance the system by perishable items. (1.5% foods. (2.5% yield was yield was perishable ) perishable ) enabling a more cooperative living among several environments. This would allow different plantations toLabour hours 2 labour hours per day 16 labour hours per day communicate with each other in case of adverse environmental scenarios. For example, when one particularMoney Initial cost, electricity Labour cost, Rework cost system has been caught up in decease, it can communicate cost this situation to other environments enabling them to takeReliability Reliable Reliable necessary precautions pro-actively.Response Very High Average ACKNOWLEDGEMENTtimeUsability Very High Average All the faculty members and our colleagues deserve to be appreciated for contributing to the success of situations fine. this project in various ways. Also the authors of the references we have used throughout this project are highly Also SAS_EN was tested for special scenarios such as appreciated. multiple conditions going adverse. For example when water level goes down and the day light fade SAS_EN could tolerate such situations as well. REFERENCES  A. Najam, D.Runnels, M. Halle Environment and globalization, five TABLE 3: THE DEPLOYEMENT RESULTS OF SAS_EN propositions, International Institute for sustainable development, Ministry of Foreign affairs of Denmark, 2007 Function Performance Evaluation  B. Malheiro and E. Oliveira, “Environmental Decision Support: a Multi-Agent Approach”, Proceedings of Autonomous Agents 97,Adjust EC and PH Levels 10 min for 20 m2 plantation ACM Press, 1997, pp. 540-541.  C.W., Marr, Hydroponic Systems, Greenhouse Vegetable ProductionAdjust Light 3 min for 3 bulbs  D. Mohsen, easy gardening with hydroponics for teachers, gardnersAdjust Water Level 6 min for 20 m2 plantation and home hobbyist  D.T, Bourgues, S., Wit, R., D., Auby, I., Effects on plantAdjust Ventilation 15 min for 20 m2 plantation photosynthesis, carbon sources and ammonium availability on nitrogen fixation rates in the rhizosphere of Zostera nolti, welsh,Adjust Albert Solution 10 min for 20 m2 plantation , G. Bünemann , mineral nutrition and fruit quality of temperature zone fruit trees, Symposium on Mineral Nutrition and Fruit Quality of Temperate Zone Fruit Trees, 1980  G. Weiss, Multiagent Systems: A Modern Introduction to Distributed Artificial Intelligence, Cambridge, MIT Press, MA, 1999.  http://hmeter.sf.net
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