2009 First International Conference on Computational Intelligence, Communication Systems and Networks
Wireless System for Monitoring Environmental variables of Rain Shelter House (RSH) Saiful Farhan M. Samsuri, Robiah Ahmad, Mohamed Hussein, Abd. Rahman Abdul Rahim Faculty of Mechanical Engineering, Universiti Teknologi Malaysia
[email protected],
[email protected],
[email protected],
[email protected] aspects of agricultural enterprises [5]. Information collected from these sensor nodes is routed to a sink node via different types of wireless communication approaches [6]. Currently three main wireless standards are used namely: WiFi, Bluetooth and ZigBee. The benefits of using the wireless technologies in agriculture resulted in a large number of research projects in this application domain [7]-[8]. Chili, or its biological name capsicum annum, is commonly planted in Malaysia as well as other Asian countries. This tropical crop is planted at lower ground region. Mostly, planting all these vegetables are done by conventional method at open ground which could lead to suffer high risk problem such as insect and disease attack, high exposure of solar radiation, hot weather and heavy rain and wind that can damage the plant [9]. Changes in environmental parameters such as temperature, humidity, light, minerals and soil condition can have a profound effect on the productivity and quality on the growth of any plant. Therefore the plantation needs closed monitoring of the environment variables which can give favourable environment to prevent the growth of pests and undesirable organisms that can damage the plants [10]. The use of RSH could reduce these problems, however the environment effect is much depends on climate change. The diseases for chili plant are great concern to farmers among them are leaf mould, mildew, root disease, etc [11]. These diseases can be controlled through monitoring of the plant growth, using pesticides, and taking early detection of any problems to the plant. Therefore, for optimum growth of chili plant, the environmental monitoring system should be proposed. Beside RSH, irrigation system is another component for wireless monitoring system to be studied and developed in this project. Allen, 2000 [12], evaluated an irrigation management system that could provide continuous real-time or near real-time soil water content information to system operator.
Abstract Wireless system is one of the technologies currently applied in agriculture to improve quality, save labour costs, increase yields, and conserve water. A real-time wireless monitoring system for measuring climatic environment parameters of rain shelter house (RSH) for chili plantation was developed. The wireless monitoring system integrates the hardware and software components for the measurement of environment parameters that can affect the growth of chili, such as temperature, humidity, solar radiation and etc. The system described here offers real potential for monitoring spatially environment variables. This paper describes the component for the developed wireless monitoring system of chili (capsicum) plantation discusses the experimental results acquired and the relationships between those parameters. The experimental results showed our proposed system is very feasible for future applications towards precision agriculture and it has potential to offer great technologies in modernizing the agricultural sector.
1. Introduction A sensor network can be characterized as a number of communication-capable sensor units used in an application. Using wireless technology, these sensors are placed directly to the climatic environmental variables to be monitored [1]. In agriculture field, some factors such as dynamic and slow reaction of the environment changes, and large amount of environment related data to consider make it hard to monitor these variables by human [2]. Wireless network system can be deployed to solve the problems especially in difficult area to reach particularly in large plantation areas. The system can be applied to a wide range of agricultural concerns from daily herd management through horticulture to field crop production [3]-[4], well pre- and post-production 978-0-7695-3743-6/09 $25.00 © 2009 IEEE DOI 10.1109/CICSYN.2009.65
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(RH) [11]. In order to achieve this, the requirement for the developed wireless monitoring system should consist of sensors, nodes, data and information systems, and control system (Sensors and Actuators).
However, this system required the operator to visit the data loggers for data downloading and thus did not provide a wireless solution. Shock et al. 1999 [13] used a similar approach but transmitted data from the data loggers to a central data logging site via radio. This system connects sensors to be wired into a proprietary data logger/transmitting box. But, unless all the sensors were placed in close proximity to the data logger, this system still required extensive cabling. King et al. 2000 [14] proposed the architecture for a distributed sensor network which included controls for a variable rate irrigation system. Although this approach may accommodate a large number of sensors, at this point, it is still a theoretical system [15]. The knowledge in real time of this information allows greater reliability in environmental climatic forecasts, and the more frequent collection of the necessary climatic data helps refine research [16]. The objective of this research is to design, develop and analyze a wireless system for monitoring climatic environmental variables in RSH for chili plantation. The sensor network is used in this study to provide constant monitoring of field-environment factors where real time information from the fields will provide information to farmers. It is hoped that the developed wireless monitoring system will help farmers monitor their plant therefore could implement remote control strategy to the plantation. After introduction in section 1, this paper presents the wireless monitoring system requirements in Section 2, system architecture in Section 3, and system components in Section 4. Section 5 discusses some experiments results. Finally concluding remarks on the paper are summarized in Section 6.
3. Description of System Components Two main components in the chili plantation are the rain shelter house (RSH) and fertigation system. The next subsections describe briefly the developed components.
3.1. Rain Shelter House (RSH) The purpose for integrating the fertigation system and the Rain Shelter House (RSH) is to prevent the high risk of damage factor usually faces in conventional open field crop such as soil infertility, heavy rain, weedicides and crucial insects and diseases [17]. The developed experimental rain shelter house model was adapted from the greenhouse concept without climate control inputs (such heating, fog system and etc) involved. Typically, the RSH also called Naturally Ventilated Tropical Green House (NVTG) by the Malaysian Agricultural research and Development Institute, MARDI [18]. The RSH was constructed from galvanized steel tube structural frames with hemisphere transparent polyethylene roofing of 200 square feet area, and transparent polyethylene insect-screen side wall. The actual environmental parameters to be monitored and controlled for the rain shelter house are from local surrounding climate and meteorological condition. Initially, to understand the parameters involved in the system, a mathematical equations for the system are defined. Based on energy balance for temperature (Eq. 1) and water mass balance for the humidity (Eq. 2) [19], the equations can be defined by;
2. Requirement for wireless monitoring system based RSH
dTi (t ) = (c1 + c1Ov (t ))(Toe (t ) − Ti (t )) + c3Ch(t ) + c4 R(t ) (1) dt dH i (t ) = (d1 + d1Ov (t ))(H o (t ) − H i (t )) + (d3 + d 4 R(t ))ΔH i (t ) (2) dt
During the growth of chili plantation, the favourable ranges of values for temperature, humidity, solar radiation, wind speed and soil moisture are different. The monitoring system developed is hoped to help farmers monitor the entire growth process of the plantation. The environment parameters measured in this RSH are later be controlled by several subsystems such as irrigation system, ventilation and cooling system, and fogging system. These subsystems will be activated based on the measured values of those environmental variables from the developed monitoring system. The objective is to provide the crops with favourable climate for the growth of chili. The environmental climate condition required in general cultural practice are 120-280 W/m2 of light, 22-30oC of temperature, 55-95%r of Relative Humidity
where To, Ti, Hi, Hi are the external and internal temperatures and absolute humidity, R is solar radiation, Ov is roofing, and Ch is heating input. The coefficients ci and di are general parameters of the model. For modelling and simulation purpose, the equation used is based on the second order NARX model equations [20]-[21] where the control input Ov and Ch are ignored. The model equations given described the dynamics of the air temperature and relative humidity described by Equation below are used,
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ª Ti (t ) − To (t ) º « » R(t ) [b1b2b3b4 ] « » Tie (t ) = −1 −2 1 + a1q + a2 q « (Tpipe − Ti ) » « » ¬(Ti − To ) × uveat (t )¼
(3)
ª( H i − H o ) × uveat (t ) º « » Ti (t ) « » « H i (t ) − H o (t ) » « » ¬«(Tpipe − Ti ) × uheat (t )¼»
(4)
H ie (t ) =
[b1b2b3b4 ] 1 + a1q −1 + a2 q −2
MDFS was installed inside the RSH by using automatic irrigation controller, water pump, filter, valves, high density polyethylene (HDPE) tubes, and arrow dripper. In this project, the field is equipped with a fertigation system which irrigates fertilizer solution directly to the plant using 2 liter/hour arrow dripper. Initially, the digital timer was installed at the irrigation pivot point (pump) and was set 5 minutes every an hour for irrigation scheduling period starting at 9 am till 4 pm. Throughout the period of between planting until May 31, regular uniform irrigation applications were applied to ensure germination and a uniform stand. The smart sensor nodes were installed in mid February and began recording data in April at which time the predetermined irrigation scheduling protocols were initiated.
Where Tie is the estimate inside humidity, and Hie is the estimate outside humidity, ai is denotes denominator parameters of the transfer function, bi is the polynomials delay operators, To is outside temperature, Ti is inside temperature, R is the outside solar radiation, Tpipe is the temperature of heating pipes, uvent is the ventilation inputs (wind speed), Hi is the inside humidity, and Ho is the outside humidity. These equations described the physical features of RSH involved and also defined the environmental factors involved in the monitoring process of the plantation. In this research, chili (Capsicum Annum) seedlings were transplanted on January 2009, in a white poly bag filled with cocoa peat media. 30 poly bags were laid paired rows. The fertilizer, pesticide and weeding spraying application were conducted according to recommendations provided by Malaysian Agriculture Department. The developed RSH for wireless monitoring system of chilli plantation is located in Control and Automation laboratory, Universiti Teknologi Malaysia as shown in Figure 1.
4. Wireless monitoring requirements component
system
4.1. Sensors Several sensors namely humidity, temperature, etc, were installed and connected to an acquisition system. Watermark [22] soil moisture sensor was used to measure soil moisture. The measured moisture range is 0 ~ 200 cbars. The combined temperature and humidity sensor [23] was used in order to measure the temperature and moisture inside and outside of the RSH. The range of measured temperature is 0 ~ 60ºC ±1ºC while the range of detected moisture is 20 ~ 95 %RH ±5%RH. Illumination was also measured by using of the Light-to-voltage optical sensors that have High irradiance responsivity typically 137 mV/(μW/cm2) at Ȝp = 635 nm [24]. The wind speed sensor used here in range 0.5 ~ 2.0 m/s. The completed architecture the wireless monitoring system is shown as in Figure 2. Solar radiation
Figure 1. The developed RSH for chilli plantation. WiFi DAQ
3.2. Fertigation System
Temperature
PC/laptop (Integrated WiFi)
Fertigation (combination of ‘fertilizer’ and ‘irrigation’) is one of chemigation (Chemical & Irrigation) components and is the current method in application and distribution of fertilizer substance to the plant or crop root zone. [17]. This type of irrigation becomes more optimized because fertilizers are not washed away by surface runoffs. The system currently practices Micro-Drip Fertigation System (MDFS) especially in tropical and lowland area [18]. The
Wind speed
Humidity Rain shelter house
Fertigation System WiFi DAQ
Soil moisture
WiFi DAQ
Actuator System (to be developed)
pH sensor EC sensor
Figure 2. The developed architecture of wireless field signals monitoring system. 121
4.2. Data acquisition unit
5. Result and Analysis
WiFi DAQ (Data Acquisition) was used to provide a wireless interface between the circuit board and the receiving station which utilized IEEE 802.11b/g wireless communication. It uses direct sensor connectivity and the device can stream data on each channel at more than 50 kS/s with 24 bits of resolution. The WiFi DAQ used in the proposed system is a combination DAQ system and a module produced by National Instruments [25]. The module provides a universal input connection much like a standard serial cable that use for signal conditioning process. Connections are made dynamically and can be established between 9219 module and sensor module or between several sensor modules and a server module. A notebook computer, housed in an experimental room next to the plant, was used to run the developed software and to log and store the sensor signal data (node identifiers and the sensor values) in a delimited file. The data were transferred from the receiver to the laptop via a wireless Ethernet connection (WiFi).
This section describes the measurements of the climate environment captured during the early month of 2009 and relationships of those measured parameters. Data were captured in 24 hours for 30 second sampling rate with no raining occurred on that day. Data were captured and plotted as in Figure 4. Temperature in and Temperature out VS No. of
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Tin Tout
Temperature,
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Humidity in and humidity out VS No. of data
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Relative Humidity, (%)
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4.3. Software In order to incorporate the sensor and the wireless monitoring system, the system used Graphical User Interface (GUI) environment to create data acquisition, analysis, and display applications that use the programming structures and data types. It applies basic design templates and architectures for the system applications to make it more users friendly. Most of field monitoring system applications use mobile device and PC as main monitoring device in their system. The developed software is currently providing monitoring and control capabilities for the system as shown in Figure 3.
80
70
60 Hin Hout 50
500
0
No. of data
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(b)
Irradiance VS No. of data
2
Irradiance, (W/cm )
0.04
0.03
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0.0
0
50
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Windspeed VS No. of data 1.50
Windspeed,
1.48
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1.44
Figure 3. Sample data for wireless monitoring of
0
500
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(d)
environmental climates.
Figure 4. Experimental data from the developed wireless monitoring system (1-day measurement).
The data acquired are inside and outside temperatures, inside and outside humidity, wind speed and radiation.
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5.1. Measured RSH environmental parameters
To look relationship between all captured data, these data were superimposed using normalized data as shown in Figure 5 below.
For demonstration purposes, Figures 4(a) and 4(b) show the temperature and humidity data, while Figures 4(c) and 4(d) show the solar radiation and wind speed response in number of sample domain respectively for whole one day of 22th Mac 2009. The graphs illustrate that the wireless system and these sensors have successfully monitored the environmental climate effects. From Figures 4(a) and 4(b), we can conclude that there were relation between humidity and temperature where the value of temperature inversely proportional to the relative humidity value, as shown as in Figure 5. It also shows that the temperature and humidity distribution value track due to environmental climate change (cold in morning, hot in midday and return cold in evening). From Figures 4(c), it can be said the solar radiation value increases momentarily in the early morning and constantly at the higher level till the early night then decrease at that moment. But for wind speed data (Figures 4(d)), fluctuation of data is recorded between 1.45-1.5m/s due to unpredictable environment change. The data of the environmental climatic parameters for chilli plantation for 1-day and 3-day measurements have successfully be obtained. Future works will involve developing a robust environmental control system to provide a fully automated, close-loop control operation in moving towards precision agriculture. As an example, ventilation system will operates when the relative humidity measure more than 60% or the fogging or mist system will start when temperature measure are over limit (more than 32oC). These actions allow optimum climates for the growth of chili plantation.
Humidity in, Temperature in, Irradiance VS No. of data 1.0
0.8
0.6
Tin Hin Rad
0.4
0.2
0.0 0
1000
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1500
Figure 5. Superimposed data results for environmental climate.
The data for 3-day measurement was also acquired to get the general pattern of the environmental climates parameters for RSH and the parameters involved are wind speed, irradiance, inside and outside temperature and inside and outside humidity respectively as shown in Figure 6.
6. Summary The wireless monitoring system described here offers on-line monitoring of environmental parameters for chili plantation. The system was able to successfully monitor climate environment of RSH namely temperature, humidity, wind speed and illumination status during growing season of the plantation. Equipment modifications resulting from encountered problems can be done for a more robust system that can be installed at the beginning of the season and left alone until harvest. The wireless monitoring system reliably captured and transmitted the signals from of the sensors and allowed us to monitor and analyse the data successfully. The relatively low cost of the sensor nodes allows for installation of a dense population of sensors that can adequately represent the inherent soil variability
Figure 6. Experimental data from the developed wireless monitoring system (3-day measurement). 123
present in any field.
[12] R.G. Allen, 2000a. “Report on AM400 and HOBO loggers”, University of Idaho, Kimberly, Idaho, www.kimberly.uidaho.edu/water/swm/.
7. Acknowledgements
[13] C.C Shock, J.M. Barnum, M. Seddigh, “Callibration of Watermark soil moisture sensor for irrigation management”, In; Proceedings of the 1998 Irrigation Association Technical Conference, Fall Church, VA USA, 1998, pp. 123-129.
We are grateful to UTM and MOSTI for funding this project under research fund (Grant number: 06-0106-SF0395). We thank all our partners and contributors, and particularly the communities with which we are working.
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