- Email: [email protected]
Application of Integrated Control Strategy and Bluetooth for Irrigating Romaine Lettuce in Greenhouse
5th IFAC Conference on Sensing, Control and Automation for 5th IFAC Conference on Sensing, Control and Automation for Agriculture 5th IFAC Conference on Sensing, Control and Automation for Available Agriculture August 14-17, 2016. Seattle, Washington, USA online at www.sciencedirect.com Agriculture August 14-17, 2016. Seattle, Washington, USA August 14-17, 2016. Seattle, Washington, USA
ScienceDirect
IFAC-PapersOnLine 49-16 (2016) 381–386
Application of Integrated Control Strategy and Bluetooth for Irrigating Romaine Application Strategy and Application of of Integrated Integrated Control Control Strategy and Bluetooth Bluetooth for for Irrigating Irrigating Romaine Romaine Lettuce in Greenhouse Lettuce in Greenhouse Lettuce in Greenhouse Gu-Zhah Hong*. Ching-Lu Hsieh** Gu-Zhah Ching-Lu Gu-Zhah Hong*. Hong*. Ching-Lu Hsieh** Hsieh** *Department of Biomechatronics Engineering, National Pingtung University of Science and Technology *Department Engineering, Pingtung of Pingtung, Taiwan, ROCNational (e-mail: rs930410@ gmail.com). *Department of of Biomechatronics Biomechatronics Engineering, National Pingtung University University of Science Science and and Technology Technology Pingtung, Taiwan, ROC (e-mail: rs930410@ gmail.com). ** Department of Biomechatronics Engineering, National Pingtung University of Science and Technology Pingtung, Taiwan, ROC (e-mail: rs930410@ gmail.com). ** of Engineering, National of and Pingtung, Taiwan, ROC (e-mail: [email protected]). Coorpesponding ** Department Department of Biomechatronics Biomechatronics Engineering, National Pingtung Pingtung University University of Science Scienceauthor} and Technology Technology Pingtung, Taiwan, ROC (e-mail: [email protected]). Coorpesponding author} Pingtung, Taiwan, ROC (e-mail: [email protected]). Coorpesponding author} Abstract: A greenhouse usually is a costly facility that can offer better environment for crops. Thus, to Abstract: A greenhouse greenhouse usually is aa costly costly facility facility that can can offer better environment for crops. crops. Thus, to to efficiently operate the facility in greenhouse is important for offer farmers. This study compared conventional Abstract: A usually is that better environment for Thus, efficiently operate the facility in greenhouse is important for farmers. This study compared conventional timer control and the soilfacility moisture control method with anfor integrated strategy (ICS)conventional in wireless efficiently operate in greenhouse is important farmers. control This study compared timer control and soil moisture moisture control method method with an an integrated integrated control weather strategysensor, (ICS) in in wireless irrigation that and consisted of microcontroller, programmable logic controller, soilwireless sensor timer control soil control with control strategy (ICS) irrigation that consisted of microcontroller, programmable logic controller, weather sensor, soil sensor and Bluetooth module. Two two-week field programmable experiments were grow Romaine and irrigation that consisted of microcontroller, logicconducted controller,to weather sensor, lettuce soil sensor and Bluetooth module. Two two-week field experiments were conducted to grow Romaine lettuce and Red Bluetooth lettuce in module. greenhouse. showed in test were groupconducted (with ICS) performance in and TwoResults two-week field plants experiments to had growhigher Romaine lettuce and Red lettuce in greenhouse. Results showed plants in test group (with ICS) had higher performance in plant height, leaf number, fresh weight and dry weight. A statistic ANOVA indicated significant different Red lettuce in greenhouse. Results showed plants in test group (with ICS) had higher performance in plant height, leaf number, fresh weight and dry weight. A statistic ANOVA indicated significant different in mean between the two groups (test group and check group). Result of evaluation for electricity and plant height, leaf number, fresh weight and dry weight. A statistic ANOVA indicated significant different in mean between the two two the groups (test group and check group). Result ofwater evaluation for electricity electricity and water usage also presents ICS (test couldgroup save and 90%check of thegroup). electricity andof usage when comparedand to in mean between the groups Result evaluation for water usage also presents the ICS could save 90% of the electricity and water usage when compared to the timer control method. water usage also presents the ICS could save 90% of the electricity and water usage when compared to the timer control method. the timerIFAC control method. Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved. © 2016, (International Keywords: Bluetooth, Integrated control. Irrigation, Romaine lettuce, Wireless control Keywords: Bluetooth, Integrated control. control. Irrigation, Irrigation, Romaine Romaine lettuce, lettuce, Wireless Wireless control control Keywords: Bluetooth, Integrated
1. INTRODUCTION 1. 1. INTRODUCTION INTRODUCTION Greenhouse offers a protection and a better environment for Greenhouse aa protection and aa better crops so as tooffers improve the quality yield environment of the crops. for It Greenhouse offers protection andand better environment for crops so as to improve the quality and yield the crops. has been applied in horticulture especially for crops so as to improve the quality and yield of ofoff theseason crops. It It has in horticulture for season production and for highespecially quality crops. has been been applied applied inculturing horticulture especially for off offGreenhouse season production culturing quality crops. Greenhouse usually is a and highfor cost facility.high Thus, how to use the facility production and for culturing high quality crops. Greenhouse usually is a high cost facility. Thus, how to use the more efficiently is important to the farmers. usually is a high cost facility. Thus, how to use the facility facility more more efficiently efficiently is is important important to to the the farmers. farmers. Meanwhile, to save wiring cost and hardness as well as to Meanwhile, save cost and well obtain more to efficient control, wireless sensingas Meanwhile, to save wiring wiring cost and hardness hardness asnetworks well as as to to obtain more efficient control, wireless sensing networks (WSN)more are applied recently open field and innetworks greenhouse obtain efficient control,inwireless sensing (WSN) applied in field in (Wang, are et al., 2006).recently The WSN technologies point(WSN) are applied recently in open open field and and includes in greenhouse greenhouse (Wang, et al., 2006). The WSN technologies includes to-point communications, point-to multi-point (Wang, et al., 2006). The WSN technologies includes pointpointto-point communications, point-to multi-point communications, in short range, such as Bluetooth and to-point communications, point-to multi-point communications, in range, such as and ZigBee; or multi-hop wireless local network (WLAN) in communications, in short short range, sucharea as Bluetooth Bluetooth and ZigBee; or multi-hop wireless local area network (WLAN) mid-range, and cellular phone systems, such as GSM/GPRS ZigBee; or multi-hop wireless local area network (WLAN) in in mid-range, and cellular systems, such GSM/GPRS for long-range. is a global wireless mid-range, and Bluetooth cellular phone phone systems, such as ascommunication GSM/GPRS for Bluetooth is wireless standard that connects devices together over acommunication certain for long-range. long-range. Bluetooth is aa global global wireless communication standard that connects devices together aa certain distance usually 10 m to 100 m.together Becauseover of its advantages of standard that connects devices over certain distance usually m 100 m. Because of its of low power, easy 10 to use it was into billions distance usually 10 m to toand 100low m. cost, Because of built its advantages advantages of low power, easy to use and low cost, it was built into billions of products on the market today and connected the Internet of low power, easy to use and low cost, it was built into billions of products on the market today and connected the Internet Things (Bluetooth, 2016). of products on the market today and connected the Internet of of Things Things (Bluetooth, (Bluetooth, 2016). 2016). A Bluetooth device uses radio waves to connect to a phone or A uses radio to to or computer. A device Bluetooth contains a tiny computer chip A Bluetooth Bluetooth device usesproduct radio waves waves to connect connect to aa phone phone or computer. A Bluetooth product contains a tiny computer chip with a Bluetooth radio and software that amakes it connect.chip computer. A Bluetooth product contains tiny computer with Bluetooth radio and it connect. Whenaa two Bluetooth want tothat talkmakes to each they with Bluetooth radiodevices and software software that makes it other, connect. When two Bluetooth devices want to talk to each other, need totwo pair. Communication between Bluetooth When Bluetooth devices want to talk to eachdevices other, they they need to between Bluetooth happens overCommunication short-range, ad hoc networks knowndevices as piconets. need to pair. pair. Communication between Bluetooth devices happens over short-range, ad networks known as The network from two to eight connected happens over ranges short-range, ad hoc hoc networks knowndevices. as piconets. piconets. The network ranges from two to eight connected devices. When a network is established, one device takes the role of The network ranges from two to eight connected devices. When aa network is one the role the master while all the other devices act astakes slaves. When network is established, established, one device device takes thePiconets role of of the master while all the other devices act as slaves. Piconets the master while all the other devices act as slaves. Piconets
are established dynamically and automatically as Bluetooth are dynamically automatically as devices enter and leave radioand proximity (Bluetooth, 2016). are established established dynamically and automatically as Bluetooth Bluetooth devices enter and leave radio proximity (Bluetooth, devices enter and leave radio proximity (Bluetooth, 2016). 2016). Among researchers of using Bluetooth in agriculture, Lee et Among researchers of using Bluetooth in agriculture, Lee al. (2002) used Bluetooth, DGPS, and load cells to transmit Among researchers of using Bluetooth in agriculture, Lee et et al. (2002) used Bluetooth, DGPS, and load cells to transmit moisture data to hostDGPS, computer and create al. (2002)sensor used Bluetooth, and load cells toa silage transmit moisture data to create corn yieldsensor map for a site-specific crop and management. Kim et moisture sensor data to host host computer computer and create aa silage silage corn yield map for a site-specific crop management. et al., (2006a) developed a WSN irrigation system that Kim collected corn yield map for a site-specific crop management. Kim et al., (2006a) developed a WSN irrigation system that collected soil and weather information then wirelessly transmitted to a al., (2006a) developed a WSN irrigation system that collected soil and weather information then wirelessly transmitted to base station by Bluetooth antenna. They also applied the soil and weather information then wirelessly transmitted to aa base by antenna. also the Bluetooth module along withThey a self-propelled base station stationradio by Bluetooth Bluetooth antenna. They also applied appliedlinear the Bluetooth radio module along with a self-propelled linear sprinkler system with a programmable logic controller (PLC) Bluetooth radio module along with a self-propelled linear sprinkler system with a programmable logic controller to maintain a variable rate water irrigation (Kim et al., 2006b). sprinkler system with a programmable logic controller (PLC) (PLC) to to maintain maintain aa variable variable rate rate water water irrigation irrigation (Kim (Kim et et al., al., 2006b). 2006b). Sun, soil, and water are important for crop growth. How to Sun, soil, water are crop growth. maintain proper water supply forfor crop is crucial cropto Sun, soil,aand and water are important important for crop growth.inHow How to maintain a proper water supply for crop is crucial in production, qualitywater maintenance, water conservation. maintain a proper supply forand crop is crucial in crop crop production, quality conservation. Among many kindsmaintenance, of irrigations,and dripwater irrigation has been production, quality maintenance, and water conservation. Among many kinds of irrigations, drip irrigation accepted because of its efficiency in water saving andbeen control Among many kinds of irrigations, drip irrigation has has been accepted because of its efficiency in water saving and precision. accepted because of its efficiency in water saving and control control precision. precision. Hsieh et al, (2010) used drip irrigation for cherry tomato in Hsieh drip tomato in greenhouse. Resultsused showed reductionfor ofcherry the fruit cracking Hsieh et et al, al, (2010) (2010) used drip airrigation irrigation for cherry tomato in greenhouse. Results showed a reduction of the fruit cracking ratio and an increase of total asoluble solids plants were greenhouse. Results showed reduction of when the fruit cracking ratio and an of plants were irrigated little amount water. solids Jou et when al.,(2015) applied ratio and with an increase increase of total totalofsoluble soluble solids when plants were irrigated with little amount of water. Jou et al.,(2015) applied PLC and with environmental sensors to control irrigation irrigated little amount of water. Jou etdrip al.,(2015) applied PLC sensors drip system pot plants in semi-closed type greenhouses. The PLC and andforenvironmental environmental sensors to to control control drip irrigation irrigation system for pot plants in semi-closed type greenhouses. environmental conditions include solar radiation, temperature system for pot plants in semi-closed type greenhouses. The The environmental conditions include radiation, temperature and relative humidity. Chen et al.,solar (2015) compared environmental conditions include solar radiation, temperature and relative humidity. Chen et (2015) compared fertigation irrigation with fertilizer) traditional and relative(drip humidity. Chen et al., al., (2015) and compared fertigation (drip irrigation with fertilizer) and furrow irrigation with fertilizer for Eustoma plant. Result fertigation (drip irrigation with fertilizer) and traditional traditional furrow irrigation for plant. Result shows couldfertilizer benefit both in cut flower furrowfertigation irrigation with with fertilizer for Eustoma Eustoma plant.quality Result and shows fertigation could benefit both in cut flower quality saving fertigation water and fertilizers. shows could benefit both in cut flower quality and and saving saving water water and and fertilizers. fertilizers.
2405-8963 © 2016, IFAC (International Federation of Automatic Control) Copyright 2016 IFAC 386Hosting by Elsevier Ltd. All rights reserved. Peer review©under of International Federation of Automatic Copyright 2016 responsibility IFAC 386Control. Copyright © 2016 IFAC 386 10.1016/j.ifacol.2016.10.070
IFAC AGRICONTROL 2016 382 Gu-Zhah Hong et al. / IFAC-PapersOnLine 49-16 (2016) 381–386 August 14-17, 2016. Seattle, Washington, USA
Water can be supplies based on time by using a timer. Conventionally famers water crops on morning or afternoon. Water also can be supplied by its CWSI (Crop water stress index) of the crop (Idso et al., 1981a). CWSI uses temperature differential of leaf and air vs. air vapour pressure deficit (VPD) to represent soil moisture conditions conductive to the maintenance of potential evaporation. Idso et al. (1981b) have suggested that such a relationship can be the operational criterion for irrigation and later it was tested in field by Geiser et al. (1982). In order to use CWSI, the water-stressed baseline and on-water-stress baseline need to be calibrated first. These calibration curves depend on crop variety and need follow several processes to avoid measurement error (Gardner et al., 1992). Because the key factors of CWSI are temperature and soil moisture, it would be simpler to measure air temperature and soil moisture for irrigation decision without using CWSI calibration curve.
To obtain the microclimate information, a temperature and relative humidity sensor (EE-10, Elektronik), a solar radiation sensor (JLP02-TR, TOHO), and a four in one module (JSMHP, JETEC) for soil moisture, soil salinity, soil temperature, and dielectric constant are used with a microcontroller (Mega, Arduino). Calibration equation was calculated from the sensor specification and applied in control strategy running in microcontroller and host station (a personal computer, Fig. 1) so as to transfer electrical signal (such as, voltage) to physical unit (for example, ℃). Environmental information includes air temperature (T) and relative humidity (RH), solar radiation (S) in greenhouse, and soil moisture (M). Environmental sensors
Environment control is a key issue to greenhouse which can offer better microclimate for crops. Basically temperature, humidity and radiation are three major factors controlled in greenhouse by fan, shading net and other facilities. These factors can be controlled by independently by using single senor and setting upper and lower threshold. But, generally, these factors are not independent, therefore a better control strategy should consider their interactions. Some researches named this integral control as intelligent control because the controller senses the multiple environment information and make multiple decisions with a combined algorithm. In control model, this is a multiple inputs and multiple outputs type. The control algorithm can be adaptive that sensing the needs of crops in real time and set the output to meet the requirement. Or, we can set the output with prior knowledge on input conditions so as to skip the physiological model that usually is a time-consuming task.
Irrigation pump
Microcontroller A With Bluetooth
P L C
Host Station with Bluetooth
Microcontroller B With Bluetooth
Fig. 1 Schematic of the wireless irrigation system (WIS) For irrigation unit, a drip irrigation system (Youcan-agritech, Taiwan) was used which consisted of water tank, pump, valve, nutrient tank, and ratio adjustor. The water was pumped to drip nozzle thru main pipe and micro pipe, and finally to the plants. The water amount can be adjusted by number of nozzle, lateral distance of nozzle, and working duration of pump (WDP). An experiment was conducted to record water amount and soil moisture change with WDP in 5, 10, and 15 minutes parameters. The results are shown in Figure 2 and have the regression between WDP and soil moisture change as follows:
Therefore, this study integrates environmental sensors, wireless devices, PLC, and drip irrigation system to consist of a wireless irrigation system (WIS) that can be used in greenhouse. To be specific, the objectives of this study are as follows:
Y=1.2717X
1. to initiate the wireless irrigation system (WIS) with a Bluetooth module;
(1)
X: working duration of pump, WDP (min) The equation is available only for the soil below saturation condition.
2. to develop an integrated control strategy (ICS)for drip irrigation by considering air temperature, relative humidity, solar radiation, and soil moisture; 3. to compare the proposed ICS to conventional irrigation approach (timer control or soil moisture control) for Romaine Lettuce (Lactuca Sativa) and Red Lettuce (Loollo Rosa) to explore the effects on their production; This study tested Bluetooth and PLC with ICS, timer control and soil moisture control approach for plant irrigation. It tries to find a better water and energy using method for further application in greenhouse or field.
Fig. 2 Working duration of pump versus soil moisture change
2. MATERIAL AND METHOD 2.2 Control strategy 2.1 Environment sensing unit and irrigation unit 387
IFAC AGRICONTROL 2016 August 14-17, 2016. Seattle, Washington, USA Gu-Zhah Hong et al. / IFAC-PapersOnLine 49-16 (2016) 381–386
Two similar tables can be obtained for soil moisture is medium level, and other three tables can be obtained for soil moisture is low. And for soil medium is in high level, there will be no irrigation. To transfer these control tables into control code in personal computer, a BCB (Borland C++ Builder 6.0) language was used. Once the condition is met, the signal will be sent to microcontroller thru Bluetooth. The microcontroller running output control program to control PLC relay, and finally controlled the WDP of drip irrigation unit.
The control model for this study is a multiple inputs and single output model (Fig. 3). Input factors include T, RH, S, and M while output is the water amount adjusted by WDP. Each input factor was set to three levels to represent various conditions of microclimate, while, four output levels were set to control the irrigation. These levels and parameters are listed in Table 1.
T
Control system
RH
383
2.3 Experimental design
Water
R
Romani lettuce was cultured at two benches in the greenhouse. Each bench has four trays of eight seedlings in each tray. Thus, totally 64 plants were grown in the experiment. Among them, 32 plants were irrigated by WIS and named test group; the other 32 plants (check group) were irrigated by a timer conducted by the PLC. In check group, timer was set to let pump on for 15 minutes started at 7 am. The experiment one was performed for two weeks from Feb. 24th to Mar. 8th, 2016 in the campus. The schematic allocation of experimental bench and WIS systems was shown in Fig. 2.
M
T: air temperature, RH: air relative humidity, R: solar radiation, M: soil moisture Fig. 3 Control block for this study
Table 1 Control factor and level for input and output Factor
Temperature (T, ℃)
Level
3 (TL, TM, TH)*
Parameter of Low, Medium, and High
Below 15 15~30 Above 30
Input Solar Relative humidity radiation (S, (RH, %) W/m2) 3 3 (RHL, (SL, SM, RHM, SH) RHH) Below Below 50 30 50~80 30~100 Above Above 80 100
Soil moisture (M, % wb) 3 (ML, MM, MH) Below 70 70~75 Above 75
Output WDP (min.)
4 (W1~W4)
W1: 0 min. W2: 3 min. W3: 6 min. W4: 9 min.
1: Irrigation pump, 2: growth bench of check group, 3: growth bench for test group, 4: host station, 5: sensing unit, 6: water tank.
*: subscript of L, M, and H means low, medium, and high level respectively.
Fig.2 Schematic diagram of experimental site An experiment two was conducted from May to June, 2016 to change strategy for check group that sensing moisture content of soil and the irrigation pump was on for 10 minutes when the soil moisture less than 70% and on for 5 min. when moisture content was 70 to 75%. During the experiment, height and number of leaves were recorded on weekly base, while the weight of each plant (dry weight and fresh weight) was measured after plants were harvested. Medium for the plants growth was a commercial product (7-03, Dayi Argitech Cooperation, Taiwan) both for test and check group. The water irrigated to plant was mixed with nutrient (No.2, iGarden, Taiwan). The nutrient was diluted with water by ratio of 1:5000. For the two-week period of test, no additional control was conducted to air environment.
Therefore, totally there are 81 combinations (34=81) for the input control. One of example is listed in Table 2 that suggests working duration of pump (WDP) is nine minutes (WDP=W3) when solar radiation is large than 100 W/m2, air temperature over 30 ℃, relative humidity less than 50%, and soil moisture is in between 70 to 85%. Table 2 One example of irrigation control table for soil moisture is medium (MM)
RHH RHM RHL
TL W1 W1 W1
SH* TM W1 W1 W2
TH W1 W2 W3
2.4 Bluetooth transmission in field
*: For each symbol meaning, please refer to Table 1.
388
IFAC AGRICONTROL 2016 384 Gu-Zhah Hong et al. / IFAC-PapersOnLine 49-16 (2016) 381–386 August 14-17, 2016. Seattle, Washington, USA
The applied module of Bluetooth (RN41) is Class 1 that has transmission distance of 100 m with 15dBm output transmitter at frequency 2402 ~ 2480MHz. The block condition of path affects the data transmission between sender (sensing unit) and receiver (the host station). Buildings, trees, and other facilities are common blocks in greenhouse application of Bluetooth. To what extent that transmission will be affected need in filed test. For this study, location 1 was chosen for the following experiment.
The Bluetooth module (RN41, RovingNetwork) with microcontroller in sensing unit was tested in field to evaluate their data transmission. The five test locations in field were shown in Fig. 3. Sensing unit located as position O and continuously sent out data with a baud rate of 115200 bps (bits per second). The PC was set at location 1 to 5, and recorded the received data every minute then saved into an ASCII file. Every location was tested two hours duration that one hour is in daytime and the other is in nigh time.
3.2 Microclimate of experimental period For the 14 days (336 hr) experimental period, the recorded air temperature had maximum and minimum temperature of 32.6 and 15.6 ℃. Most of the air temperatures were in between 30 to 15 ℃. Recorded air humidity with maximum and minimum value of 96.7% and 38.1% were observed, while solar radiation were between 0 ~400 W/m2. The soil moisture of the test period was shown in Fig. 4. In the plot, 97.3% was the highest value and 71.6% was the lowest during the test. Therefore, we can learn that, at most of test period, soil moisture was higher than 85% and lower than 100%. O: Sensing unit (signal emitted), 1~5: Host station locations (signal received) Fig. 3 Bluetooth module test in field for data transmission 3. RESULTS AND DISCUSSION 3.1 File transmission with Bluetooth in field Fig. 4 Soil moisture of test group during experiment period
Table 3 list results of data transmission of five tested locations in field. The location No.1 to No.4 received 100% files, but none was received in location 5. Fig. 3 (at previous section) shows location 1 that host station located in greenhouse which the shortest distance (about 6 meter away) to sensing unit and no obstacle in between eye of sight among these tested locations. Location 2 and 3 has one glass wall of greenhouse and one brick wall of building 1 block the signal transmission. Location 4 will has one more brick wall in eye of sight path or just one glass wall and one brick wall if signal goes the space between building 1 and 2 (the corridor area). The path to location 5 contains one more brisk wall and has distance about 26 m between host station and sensing unit.
3.3 Pump status for test group The working status of pump on test group was recorded and illustrated in Fig. 5 which indicated only seven periods were ON, and the else were OFF. The result also indicated only W2 (WDP=3 min.) was met according to the ICS control criteria.
Table 3 File transmitted in daytime/night-time with Bluetooth Location No
Fig. 5 The status of pump during experiment period
1
2
3
4
5
Send
60/60
60/60
60/60
60/60
0/0
Received
60/60
60/60
60/60
60/60
0/0
100/100
100/100
100/100
100/100
0/0
Transmission
For the experiment period, cloudy or rainy days happened many times, which caused the soil moisture was in high level condition (refer Fig.4). As a result, the pump was not set on during these conditions.
ratio %
3.4 Plants growth
389
IFAC AGRICONTROL 2016 August 14-17, 2016. Seattle, Washington, USA Gu-Zhah Hong et al. / IFAC-PapersOnLine 49-16 (2016) 381–386
the power consumption for irrigation pump. For test group of experiment one, total 21 minutes were operated for pump, and consumed 0.308 kW-hr and irrigated 630 c.c. While, the check group, the pump operated 3.5 hr for the two week experiment, and consumed 3.08 kW-hr and irrigated 6300 c.c. Therefore, ICS consumed about 10% in electricity and water consumption when compared to the timer methods. For the experiment two, test group operated 412 minutes and consumed 6.05 kW-hr for irrigating water of 12660 c.c.. The check group operated 710 minutes, consumed 10.41 kW-hr and irrigated 21900 c.c. water. Therefore, ICS only consumed about 60% electricity and water consumption when compared to soil moisture control strategy.
After 14 days, the physical properties of plant height, number of leaves, fresh weight and dry weight were measured and listed in Table 4. Each digit is the mean of 32 plants along with the standard deviation. For first week, only height and number of leave were measured because fresh weight and dry weight are destructive. Dry weight was obtained after the plants were dried in oven at 48 hr for 70 ℃. Result from the table shown the each value in test group was higher than that of check group. The result of ANOVA test of mean difference on two groups suggested they were significant difference on these four items.
Table 4 Comparison of physical properties for test group and check group of experiment one (Timer control, Romaine lettuce) First week Test group
Check
4. CONCLUSIONS
Second week Test group
Check group
In this study, we initiated a wireless irrigation system with an integrated control strategy (ICS) for plant in greenhouse with a Bluetooth module. Two two-week experiments were tested and result shown that the plants grown higher and heavier in test group when compared to timer strategy (experiment one) and has equivalent result when compared to soil moisture strategy (experiment two). The electricity and water consumption both were lower for the proposal method (ICS) for about one tenth or 60%. The irrigation strategy applied in here might not be an optimum one. Further study is suggested to explore improvement.
group Height (cm)
16.5±1.2*
15.9±0.7
23.5±1.1
22.4±1.2
Leave No.
6.8±0.6
6.5±0.5
7.2±0.5
6.9±0.4
Fresh weight
NA
NA
17.8±3.3
15.5±3.4
NA
NA
0.81±0.14
0.70±0.17
(g) Dry weight (g)
*: means±std. dev.
REFERENCES
Result of the second experiment was shown in Table 5 and the each value in test group was similar to that of check group. The result of ANOVA test of different mean on two groups suggested they were not significant difference on these four items based on second week’s data.
Table 5 Comparison of physical properties for test group and check group of experiment two (Soil moisture control, Red lettuce) First week Test group
Check
Second week Test group
Check group
group Height (cm)
11.8±0.5*
12.9±0.6
34.2±2.6
33.1±3.3
Leave No.
13.6±0.6
12.1±0.4
8.3±0.9
8.6±1.4
Fresh weight
NA
NA
24.7±8.9
27.6±9.2
NA
NA
1.3±0.8
1.3±0.7
(g) Dry weight
385
(g)
*: means±std. dev. 3.5 Economic evaluation To analyse the electricity used for test and check group, the accumulated working hours were used and calculated with 390
Bluetooth. 2016. Bluetooth technology basics. https://www.bluetooth.com/what-is-bluetoothtechnology/bluetooth-technology-basics. Access 2016/3/5. Chen, L., Y. Chen, Y. Kuo and W. Tsai. 2015. A comparison study on water-saving effects and cut flower quality of Eustoma cultivated in furrow and micro-irrigation conditions. Taichung District Agricultural Research and Extension Station. No.127:63-72. Gardner, B. R., D. C. Nielsen and C. C. Shock, 1992. Infrared Thermometry and the Crop Water Stress Index. I. History, Theory, and Baselines. Journal of Production Agriculture. 5(4):462-466. Gardner, B. R., D. C. Nielsen and C. C. Shock. 1992. Infrared Thermometry and the Crop Water Stress Index. II. Sampling Procedures and Interpretation. Journal of Production Agriculture. 5(4):466-475. Geiser, K. M., D. C. Slack, E. R. Allred, K. W. Stange. 1982. Irrigation Scheduling Using Crop Canopy-Air Temperature Difference. Transactions of the ASAE. 25 (3): 0689-0694. Hsieh, M. H., E. C. Liu, H. C. Hsu, W. J. Jiang and J. Y. Chung. 2010. Study on Drip Fertigation Used in Greenhouse Cherry Tomato Production. Research Reports of Tainan District Agricultural Research and Extension Station. No.59:45-53. Idso, S. B., R. J. Reginato, R. D. Jackson, P. J. PinterJr. 1981. Measuring yield-reducing plant water potential
IFAC AGRICONTROL 2016 386 Gu-Zhah Hong et al. / IFAC-PapersOnLine 49-16 (2016) 381–386 August 14-17, 2016. Seattle, Washington, USA
depressions in wheat by infrared thermometry. Irrigation Science. 2(4): 205-212 Idso, S. B., R. J. Reginato, D. C. Reicosky and J. L. Hatfield. 1981. Determining Soil-Induced Plant Water Potential Depressions in Alfalfa by Means of Infrared Thermometry. Agronomy Journal, 73(5):826-830. Jou, L., Y. Chiu, and L. Fan. 2015. Designing the Universal Type of Drip Irrigation Controller for Suitably Implemented on Irrigation Requirement and Management of Pot Plants in Greenhouses. Journal of Taiwan Agricultural Engineering. 61(2):28-46 Kim, Y., R. Evans. W. Iversen. and F. Pierce. 2006a. Instrumentation and control for wireless sensor network for automated irrigation. 2006 ASABE Annual International Meeting. Paper number: 061105 Kim, Y., R. Evans. W. Iversen. and F. Pierce. 2006b. Evaluation of Wireless Control for Variable Rate Irrigation. 2006 ASABE Annual International Meeting. Paper number: 062164 Lee, W., T. Burks, and J. Schueller. 2002. Silage yield monitoring system. ASAE Annual Meeting, paper No. 021165 Wang N., N. Zhang, and M. Wang. 2006. Review: Wireless sensors in agriculture and food industry—Recent development and future perspective. Computers and Electronics in Agriculture 50 (2006) 1–14.
391
ScienceDirect
IFAC-PapersOnLine 49-16 (2016) 381–386
Application of Integrated Control Strategy and Bluetooth for Irrigating Romaine Application Strategy and Application of of Integrated Integrated Control Control Strategy and Bluetooth Bluetooth for for Irrigating Irrigating Romaine Romaine Lettuce in Greenhouse Lettuce in Greenhouse Lettuce in Greenhouse Gu-Zhah Hong*. Ching-Lu Hsieh** Gu-Zhah Ching-Lu Gu-Zhah Hong*. Hong*. Ching-Lu Hsieh** Hsieh** *Department of Biomechatronics Engineering, National Pingtung University of Science and Technology *Department Engineering, Pingtung of Pingtung, Taiwan, ROCNational (e-mail: rs930410@ gmail.com). *Department of of Biomechatronics Biomechatronics Engineering, National Pingtung University University of Science Science and and Technology Technology Pingtung, Taiwan, ROC (e-mail: rs930410@ gmail.com). ** Department of Biomechatronics Engineering, National Pingtung University of Science and Technology Pingtung, Taiwan, ROC (e-mail: rs930410@ gmail.com). ** of Engineering, National of and Pingtung, Taiwan, ROC (e-mail: [email protected]). Coorpesponding ** Department Department of Biomechatronics Biomechatronics Engineering, National Pingtung Pingtung University University of Science Scienceauthor} and Technology Technology Pingtung, Taiwan, ROC (e-mail: [email protected]). Coorpesponding author} Pingtung, Taiwan, ROC (e-mail: [email protected]). Coorpesponding author} Abstract: A greenhouse usually is a costly facility that can offer better environment for crops. Thus, to Abstract: A greenhouse greenhouse usually is aa costly costly facility facility that can can offer better environment for crops. crops. Thus, to to efficiently operate the facility in greenhouse is important for offer farmers. This study compared conventional Abstract: A usually is that better environment for Thus, efficiently operate the facility in greenhouse is important for farmers. This study compared conventional timer control and the soilfacility moisture control method with anfor integrated strategy (ICS)conventional in wireless efficiently operate in greenhouse is important farmers. control This study compared timer control and soil moisture moisture control method method with an an integrated integrated control weather strategysensor, (ICS) in in wireless irrigation that and consisted of microcontroller, programmable logic controller, soilwireless sensor timer control soil control with control strategy (ICS) irrigation that consisted of microcontroller, programmable logic controller, weather sensor, soil sensor and Bluetooth module. Two two-week field programmable experiments were grow Romaine and irrigation that consisted of microcontroller, logicconducted controller,to weather sensor, lettuce soil sensor and Bluetooth module. Two two-week field experiments were conducted to grow Romaine lettuce and Red Bluetooth lettuce in module. greenhouse. showed in test were groupconducted (with ICS) performance in and TwoResults two-week field plants experiments to had growhigher Romaine lettuce and Red lettuce in greenhouse. Results showed plants in test group (with ICS) had higher performance in plant height, leaf number, fresh weight and dry weight. A statistic ANOVA indicated significant different Red lettuce in greenhouse. Results showed plants in test group (with ICS) had higher performance in plant height, leaf number, fresh weight and dry weight. A statistic ANOVA indicated significant different in mean between the two groups (test group and check group). Result of evaluation for electricity and plant height, leaf number, fresh weight and dry weight. A statistic ANOVA indicated significant different in mean between the two two the groups (test group and check group). Result ofwater evaluation for electricity electricity and water usage also presents ICS (test couldgroup save and 90%check of thegroup). electricity andof usage when comparedand to in mean between the groups Result evaluation for water usage also presents the ICS could save 90% of the electricity and water usage when compared to the timer control method. water usage also presents the ICS could save 90% of the electricity and water usage when compared to the timer control method. the timerIFAC control method. Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved. © 2016, (International Keywords: Bluetooth, Integrated control. Irrigation, Romaine lettuce, Wireless control Keywords: Bluetooth, Integrated control. control. Irrigation, Irrigation, Romaine Romaine lettuce, lettuce, Wireless Wireless control control Keywords: Bluetooth, Integrated
1. INTRODUCTION 1. 1. INTRODUCTION INTRODUCTION Greenhouse offers a protection and a better environment for Greenhouse aa protection and aa better crops so as tooffers improve the quality yield environment of the crops. for It Greenhouse offers protection andand better environment for crops so as to improve the quality and yield the crops. has been applied in horticulture especially for crops so as to improve the quality and yield of ofoff theseason crops. It It has in horticulture for season production and for highespecially quality crops. has been been applied applied inculturing horticulture especially for off offGreenhouse season production culturing quality crops. Greenhouse usually is a and highfor cost facility.high Thus, how to use the facility production and for culturing high quality crops. Greenhouse usually is a high cost facility. Thus, how to use the more efficiently is important to the farmers. usually is a high cost facility. Thus, how to use the facility facility more more efficiently efficiently is is important important to to the the farmers. farmers. Meanwhile, to save wiring cost and hardness as well as to Meanwhile, save cost and well obtain more to efficient control, wireless sensingas Meanwhile, to save wiring wiring cost and hardness hardness asnetworks well as as to to obtain more efficient control, wireless sensing networks (WSN)more are applied recently open field and innetworks greenhouse obtain efficient control,inwireless sensing (WSN) applied in field in (Wang, are et al., 2006).recently The WSN technologies point(WSN) are applied recently in open open field and and includes in greenhouse greenhouse (Wang, et al., 2006). The WSN technologies includes to-point communications, point-to multi-point (Wang, et al., 2006). The WSN technologies includes pointpointto-point communications, point-to multi-point communications, in short range, such as Bluetooth and to-point communications, point-to multi-point communications, in range, such as and ZigBee; or multi-hop wireless local network (WLAN) in communications, in short short range, sucharea as Bluetooth Bluetooth and ZigBee; or multi-hop wireless local area network (WLAN) mid-range, and cellular phone systems, such as GSM/GPRS ZigBee; or multi-hop wireless local area network (WLAN) in in mid-range, and cellular systems, such GSM/GPRS for long-range. is a global wireless mid-range, and Bluetooth cellular phone phone systems, such as ascommunication GSM/GPRS for Bluetooth is wireless standard that connects devices together over acommunication certain for long-range. long-range. Bluetooth is aa global global wireless communication standard that connects devices together aa certain distance usually 10 m to 100 m.together Becauseover of its advantages of standard that connects devices over certain distance usually m 100 m. Because of its of low power, easy 10 to use it was into billions distance usually 10 m to toand 100low m. cost, Because of built its advantages advantages of low power, easy to use and low cost, it was built into billions of products on the market today and connected the Internet of low power, easy to use and low cost, it was built into billions of products on the market today and connected the Internet Things (Bluetooth, 2016). of products on the market today and connected the Internet of of Things Things (Bluetooth, (Bluetooth, 2016). 2016). A Bluetooth device uses radio waves to connect to a phone or A uses radio to to or computer. A device Bluetooth contains a tiny computer chip A Bluetooth Bluetooth device usesproduct radio waves waves to connect connect to aa phone phone or computer. A Bluetooth product contains a tiny computer chip with a Bluetooth radio and software that amakes it connect.chip computer. A Bluetooth product contains tiny computer with Bluetooth radio and it connect. Whenaa two Bluetooth want tothat talkmakes to each they with Bluetooth radiodevices and software software that makes it other, connect. When two Bluetooth devices want to talk to each other, need totwo pair. Communication between Bluetooth When Bluetooth devices want to talk to eachdevices other, they they need to between Bluetooth happens overCommunication short-range, ad hoc networks knowndevices as piconets. need to pair. pair. Communication between Bluetooth devices happens over short-range, ad networks known as The network from two to eight connected happens over ranges short-range, ad hoc hoc networks knowndevices. as piconets. piconets. The network ranges from two to eight connected devices. When a network is established, one device takes the role of The network ranges from two to eight connected devices. When aa network is one the role the master while all the other devices act astakes slaves. When network is established, established, one device device takes thePiconets role of of the master while all the other devices act as slaves. Piconets the master while all the other devices act as slaves. Piconets
are established dynamically and automatically as Bluetooth are dynamically automatically as devices enter and leave radioand proximity (Bluetooth, 2016). are established established dynamically and automatically as Bluetooth Bluetooth devices enter and leave radio proximity (Bluetooth, devices enter and leave radio proximity (Bluetooth, 2016). 2016). Among researchers of using Bluetooth in agriculture, Lee et Among researchers of using Bluetooth in agriculture, Lee al. (2002) used Bluetooth, DGPS, and load cells to transmit Among researchers of using Bluetooth in agriculture, Lee et et al. (2002) used Bluetooth, DGPS, and load cells to transmit moisture data to hostDGPS, computer and create al. (2002)sensor used Bluetooth, and load cells toa silage transmit moisture data to create corn yieldsensor map for a site-specific crop and management. Kim et moisture sensor data to host host computer computer and create aa silage silage corn yield map for a site-specific crop management. et al., (2006a) developed a WSN irrigation system that Kim collected corn yield map for a site-specific crop management. Kim et al., (2006a) developed a WSN irrigation system that collected soil and weather information then wirelessly transmitted to a al., (2006a) developed a WSN irrigation system that collected soil and weather information then wirelessly transmitted to base station by Bluetooth antenna. They also applied the soil and weather information then wirelessly transmitted to aa base by antenna. also the Bluetooth module along withThey a self-propelled base station stationradio by Bluetooth Bluetooth antenna. They also applied appliedlinear the Bluetooth radio module along with a self-propelled linear sprinkler system with a programmable logic controller (PLC) Bluetooth radio module along with a self-propelled linear sprinkler system with a programmable logic controller to maintain a variable rate water irrigation (Kim et al., 2006b). sprinkler system with a programmable logic controller (PLC) (PLC) to to maintain maintain aa variable variable rate rate water water irrigation irrigation (Kim (Kim et et al., al., 2006b). 2006b). Sun, soil, and water are important for crop growth. How to Sun, soil, water are crop growth. maintain proper water supply forfor crop is crucial cropto Sun, soil,aand and water are important important for crop growth.inHow How to maintain a proper water supply for crop is crucial in production, qualitywater maintenance, water conservation. maintain a proper supply forand crop is crucial in crop crop production, quality conservation. Among many kindsmaintenance, of irrigations,and dripwater irrigation has been production, quality maintenance, and water conservation. Among many kinds of irrigations, drip irrigation accepted because of its efficiency in water saving andbeen control Among many kinds of irrigations, drip irrigation has has been accepted because of its efficiency in water saving and precision. accepted because of its efficiency in water saving and control control precision. precision. Hsieh et al, (2010) used drip irrigation for cherry tomato in Hsieh drip tomato in greenhouse. Resultsused showed reductionfor ofcherry the fruit cracking Hsieh et et al, al, (2010) (2010) used drip airrigation irrigation for cherry tomato in greenhouse. Results showed a reduction of the fruit cracking ratio and an increase of total asoluble solids plants were greenhouse. Results showed reduction of when the fruit cracking ratio and an of plants were irrigated little amount water. solids Jou et when al.,(2015) applied ratio and with an increase increase of total totalofsoluble soluble solids when plants were irrigated with little amount of water. Jou et al.,(2015) applied PLC and with environmental sensors to control irrigation irrigated little amount of water. Jou etdrip al.,(2015) applied PLC sensors drip system pot plants in semi-closed type greenhouses. The PLC and andforenvironmental environmental sensors to to control control drip irrigation irrigation system for pot plants in semi-closed type greenhouses. environmental conditions include solar radiation, temperature system for pot plants in semi-closed type greenhouses. The The environmental conditions include radiation, temperature and relative humidity. Chen et al.,solar (2015) compared environmental conditions include solar radiation, temperature and relative humidity. Chen et (2015) compared fertigation irrigation with fertilizer) traditional and relative(drip humidity. Chen et al., al., (2015) and compared fertigation (drip irrigation with fertilizer) and furrow irrigation with fertilizer for Eustoma plant. Result fertigation (drip irrigation with fertilizer) and traditional traditional furrow irrigation for plant. Result shows couldfertilizer benefit both in cut flower furrowfertigation irrigation with with fertilizer for Eustoma Eustoma plant.quality Result and shows fertigation could benefit both in cut flower quality saving fertigation water and fertilizers. shows could benefit both in cut flower quality and and saving saving water water and and fertilizers. fertilizers.
2405-8963 © 2016, IFAC (International Federation of Automatic Control) Copyright 2016 IFAC 386Hosting by Elsevier Ltd. All rights reserved. Peer review©under of International Federation of Automatic Copyright 2016 responsibility IFAC 386Control. Copyright © 2016 IFAC 386 10.1016/j.ifacol.2016.10.070
IFAC AGRICONTROL 2016 382 Gu-Zhah Hong et al. / IFAC-PapersOnLine 49-16 (2016) 381–386 August 14-17, 2016. Seattle, Washington, USA
Water can be supplies based on time by using a timer. Conventionally famers water crops on morning or afternoon. Water also can be supplied by its CWSI (Crop water stress index) of the crop (Idso et al., 1981a). CWSI uses temperature differential of leaf and air vs. air vapour pressure deficit (VPD) to represent soil moisture conditions conductive to the maintenance of potential evaporation. Idso et al. (1981b) have suggested that such a relationship can be the operational criterion for irrigation and later it was tested in field by Geiser et al. (1982). In order to use CWSI, the water-stressed baseline and on-water-stress baseline need to be calibrated first. These calibration curves depend on crop variety and need follow several processes to avoid measurement error (Gardner et al., 1992). Because the key factors of CWSI are temperature and soil moisture, it would be simpler to measure air temperature and soil moisture for irrigation decision without using CWSI calibration curve.
To obtain the microclimate information, a temperature and relative humidity sensor (EE-10, Elektronik), a solar radiation sensor (JLP02-TR, TOHO), and a four in one module (JSMHP, JETEC) for soil moisture, soil salinity, soil temperature, and dielectric constant are used with a microcontroller (Mega, Arduino). Calibration equation was calculated from the sensor specification and applied in control strategy running in microcontroller and host station (a personal computer, Fig. 1) so as to transfer electrical signal (such as, voltage) to physical unit (for example, ℃). Environmental information includes air temperature (T) and relative humidity (RH), solar radiation (S) in greenhouse, and soil moisture (M). Environmental sensors
Environment control is a key issue to greenhouse which can offer better microclimate for crops. Basically temperature, humidity and radiation are three major factors controlled in greenhouse by fan, shading net and other facilities. These factors can be controlled by independently by using single senor and setting upper and lower threshold. But, generally, these factors are not independent, therefore a better control strategy should consider their interactions. Some researches named this integral control as intelligent control because the controller senses the multiple environment information and make multiple decisions with a combined algorithm. In control model, this is a multiple inputs and multiple outputs type. The control algorithm can be adaptive that sensing the needs of crops in real time and set the output to meet the requirement. Or, we can set the output with prior knowledge on input conditions so as to skip the physiological model that usually is a time-consuming task.
Irrigation pump
Microcontroller A With Bluetooth
P L C
Host Station with Bluetooth
Microcontroller B With Bluetooth
Fig. 1 Schematic of the wireless irrigation system (WIS) For irrigation unit, a drip irrigation system (Youcan-agritech, Taiwan) was used which consisted of water tank, pump, valve, nutrient tank, and ratio adjustor. The water was pumped to drip nozzle thru main pipe and micro pipe, and finally to the plants. The water amount can be adjusted by number of nozzle, lateral distance of nozzle, and working duration of pump (WDP). An experiment was conducted to record water amount and soil moisture change with WDP in 5, 10, and 15 minutes parameters. The results are shown in Figure 2 and have the regression between WDP and soil moisture change as follows:
Therefore, this study integrates environmental sensors, wireless devices, PLC, and drip irrigation system to consist of a wireless irrigation system (WIS) that can be used in greenhouse. To be specific, the objectives of this study are as follows:
Y=1.2717X
1. to initiate the wireless irrigation system (WIS) with a Bluetooth module;
(1)
X: working duration of pump, WDP (min) The equation is available only for the soil below saturation condition.
2. to develop an integrated control strategy (ICS)for drip irrigation by considering air temperature, relative humidity, solar radiation, and soil moisture; 3. to compare the proposed ICS to conventional irrigation approach (timer control or soil moisture control) for Romaine Lettuce (Lactuca Sativa) and Red Lettuce (Loollo Rosa) to explore the effects on their production; This study tested Bluetooth and PLC with ICS, timer control and soil moisture control approach for plant irrigation. It tries to find a better water and energy using method for further application in greenhouse or field.
Fig. 2 Working duration of pump versus soil moisture change
2. MATERIAL AND METHOD 2.2 Control strategy 2.1 Environment sensing unit and irrigation unit 387
IFAC AGRICONTROL 2016 August 14-17, 2016. Seattle, Washington, USA Gu-Zhah Hong et al. / IFAC-PapersOnLine 49-16 (2016) 381–386
Two similar tables can be obtained for soil moisture is medium level, and other three tables can be obtained for soil moisture is low. And for soil medium is in high level, there will be no irrigation. To transfer these control tables into control code in personal computer, a BCB (Borland C++ Builder 6.0) language was used. Once the condition is met, the signal will be sent to microcontroller thru Bluetooth. The microcontroller running output control program to control PLC relay, and finally controlled the WDP of drip irrigation unit.
The control model for this study is a multiple inputs and single output model (Fig. 3). Input factors include T, RH, S, and M while output is the water amount adjusted by WDP. Each input factor was set to three levels to represent various conditions of microclimate, while, four output levels were set to control the irrigation. These levels and parameters are listed in Table 1.
T
Control system
RH
383
2.3 Experimental design
Water
R
Romani lettuce was cultured at two benches in the greenhouse. Each bench has four trays of eight seedlings in each tray. Thus, totally 64 plants were grown in the experiment. Among them, 32 plants were irrigated by WIS and named test group; the other 32 plants (check group) were irrigated by a timer conducted by the PLC. In check group, timer was set to let pump on for 15 minutes started at 7 am. The experiment one was performed for two weeks from Feb. 24th to Mar. 8th, 2016 in the campus. The schematic allocation of experimental bench and WIS systems was shown in Fig. 2.
M
T: air temperature, RH: air relative humidity, R: solar radiation, M: soil moisture Fig. 3 Control block for this study
Table 1 Control factor and level for input and output Factor
Temperature (T, ℃)
Level
3 (TL, TM, TH)*
Parameter of Low, Medium, and High
Below 15 15~30 Above 30
Input Solar Relative humidity radiation (S, (RH, %) W/m2) 3 3 (RHL, (SL, SM, RHM, SH) RHH) Below Below 50 30 50~80 30~100 Above Above 80 100
Soil moisture (M, % wb) 3 (ML, MM, MH) Below 70 70~75 Above 75
Output WDP (min.)
4 (W1~W4)
W1: 0 min. W2: 3 min. W3: 6 min. W4: 9 min.
1: Irrigation pump, 2: growth bench of check group, 3: growth bench for test group, 4: host station, 5: sensing unit, 6: water tank.
*: subscript of L, M, and H means low, medium, and high level respectively.
Fig.2 Schematic diagram of experimental site An experiment two was conducted from May to June, 2016 to change strategy for check group that sensing moisture content of soil and the irrigation pump was on for 10 minutes when the soil moisture less than 70% and on for 5 min. when moisture content was 70 to 75%. During the experiment, height and number of leaves were recorded on weekly base, while the weight of each plant (dry weight and fresh weight) was measured after plants were harvested. Medium for the plants growth was a commercial product (7-03, Dayi Argitech Cooperation, Taiwan) both for test and check group. The water irrigated to plant was mixed with nutrient (No.2, iGarden, Taiwan). The nutrient was diluted with water by ratio of 1:5000. For the two-week period of test, no additional control was conducted to air environment.
Therefore, totally there are 81 combinations (34=81) for the input control. One of example is listed in Table 2 that suggests working duration of pump (WDP) is nine minutes (WDP=W3) when solar radiation is large than 100 W/m2, air temperature over 30 ℃, relative humidity less than 50%, and soil moisture is in between 70 to 85%. Table 2 One example of irrigation control table for soil moisture is medium (MM)
RHH RHM RHL
TL W1 W1 W1
SH* TM W1 W1 W2
TH W1 W2 W3
2.4 Bluetooth transmission in field
*: For each symbol meaning, please refer to Table 1.
388
IFAC AGRICONTROL 2016 384 Gu-Zhah Hong et al. / IFAC-PapersOnLine 49-16 (2016) 381–386 August 14-17, 2016. Seattle, Washington, USA
The applied module of Bluetooth (RN41) is Class 1 that has transmission distance of 100 m with 15dBm output transmitter at frequency 2402 ~ 2480MHz. The block condition of path affects the data transmission between sender (sensing unit) and receiver (the host station). Buildings, trees, and other facilities are common blocks in greenhouse application of Bluetooth. To what extent that transmission will be affected need in filed test. For this study, location 1 was chosen for the following experiment.
The Bluetooth module (RN41, RovingNetwork) with microcontroller in sensing unit was tested in field to evaluate their data transmission. The five test locations in field were shown in Fig. 3. Sensing unit located as position O and continuously sent out data with a baud rate of 115200 bps (bits per second). The PC was set at location 1 to 5, and recorded the received data every minute then saved into an ASCII file. Every location was tested two hours duration that one hour is in daytime and the other is in nigh time.
3.2 Microclimate of experimental period For the 14 days (336 hr) experimental period, the recorded air temperature had maximum and minimum temperature of 32.6 and 15.6 ℃. Most of the air temperatures were in between 30 to 15 ℃. Recorded air humidity with maximum and minimum value of 96.7% and 38.1% were observed, while solar radiation were between 0 ~400 W/m2. The soil moisture of the test period was shown in Fig. 4. In the plot, 97.3% was the highest value and 71.6% was the lowest during the test. Therefore, we can learn that, at most of test period, soil moisture was higher than 85% and lower than 100%. O: Sensing unit (signal emitted), 1~5: Host station locations (signal received) Fig. 3 Bluetooth module test in field for data transmission 3. RESULTS AND DISCUSSION 3.1 File transmission with Bluetooth in field Fig. 4 Soil moisture of test group during experiment period
Table 3 list results of data transmission of five tested locations in field. The location No.1 to No.4 received 100% files, but none was received in location 5. Fig. 3 (at previous section) shows location 1 that host station located in greenhouse which the shortest distance (about 6 meter away) to sensing unit and no obstacle in between eye of sight among these tested locations. Location 2 and 3 has one glass wall of greenhouse and one brick wall of building 1 block the signal transmission. Location 4 will has one more brick wall in eye of sight path or just one glass wall and one brick wall if signal goes the space between building 1 and 2 (the corridor area). The path to location 5 contains one more brisk wall and has distance about 26 m between host station and sensing unit.
3.3 Pump status for test group The working status of pump on test group was recorded and illustrated in Fig. 5 which indicated only seven periods were ON, and the else were OFF. The result also indicated only W2 (WDP=3 min.) was met according to the ICS control criteria.
Table 3 File transmitted in daytime/night-time with Bluetooth Location No
Fig. 5 The status of pump during experiment period
1
2
3
4
5
Send
60/60
60/60
60/60
60/60
0/0
Received
60/60
60/60
60/60
60/60
0/0
100/100
100/100
100/100
100/100
0/0
Transmission
For the experiment period, cloudy or rainy days happened many times, which caused the soil moisture was in high level condition (refer Fig.4). As a result, the pump was not set on during these conditions.
ratio %
3.4 Plants growth
389
IFAC AGRICONTROL 2016 August 14-17, 2016. Seattle, Washington, USA Gu-Zhah Hong et al. / IFAC-PapersOnLine 49-16 (2016) 381–386
the power consumption for irrigation pump. For test group of experiment one, total 21 minutes were operated for pump, and consumed 0.308 kW-hr and irrigated 630 c.c. While, the check group, the pump operated 3.5 hr for the two week experiment, and consumed 3.08 kW-hr and irrigated 6300 c.c. Therefore, ICS consumed about 10% in electricity and water consumption when compared to the timer methods. For the experiment two, test group operated 412 minutes and consumed 6.05 kW-hr for irrigating water of 12660 c.c.. The check group operated 710 minutes, consumed 10.41 kW-hr and irrigated 21900 c.c. water. Therefore, ICS only consumed about 60% electricity and water consumption when compared to soil moisture control strategy.
After 14 days, the physical properties of plant height, number of leaves, fresh weight and dry weight were measured and listed in Table 4. Each digit is the mean of 32 plants along with the standard deviation. For first week, only height and number of leave were measured because fresh weight and dry weight are destructive. Dry weight was obtained after the plants were dried in oven at 48 hr for 70 ℃. Result from the table shown the each value in test group was higher than that of check group. The result of ANOVA test of mean difference on two groups suggested they were significant difference on these four items.
Table 4 Comparison of physical properties for test group and check group of experiment one (Timer control, Romaine lettuce) First week Test group
Check
4. CONCLUSIONS
Second week Test group
Check group
In this study, we initiated a wireless irrigation system with an integrated control strategy (ICS) for plant in greenhouse with a Bluetooth module. Two two-week experiments were tested and result shown that the plants grown higher and heavier in test group when compared to timer strategy (experiment one) and has equivalent result when compared to soil moisture strategy (experiment two). The electricity and water consumption both were lower for the proposal method (ICS) for about one tenth or 60%. The irrigation strategy applied in here might not be an optimum one. Further study is suggested to explore improvement.
group Height (cm)
16.5±1.2*
15.9±0.7
23.5±1.1
22.4±1.2
Leave No.
6.8±0.6
6.5±0.5
7.2±0.5
6.9±0.4
Fresh weight
NA
NA
17.8±3.3
15.5±3.4
NA
NA
0.81±0.14
0.70±0.17
(g) Dry weight (g)
*: means±std. dev.
REFERENCES
Result of the second experiment was shown in Table 5 and the each value in test group was similar to that of check group. The result of ANOVA test of different mean on two groups suggested they were not significant difference on these four items based on second week’s data.
Table 5 Comparison of physical properties for test group and check group of experiment two (Soil moisture control, Red lettuce) First week Test group
Check
Second week Test group
Check group
group Height (cm)
11.8±0.5*
12.9±0.6
34.2±2.6
33.1±3.3
Leave No.
13.6±0.6
12.1±0.4
8.3±0.9
8.6±1.4
Fresh weight
NA
NA
24.7±8.9
27.6±9.2
NA
NA
1.3±0.8
1.3±0.7
(g) Dry weight
385
(g)
*: means±std. dev. 3.5 Economic evaluation To analyse the electricity used for test and check group, the accumulated working hours were used and calculated with 390
Bluetooth. 2016. Bluetooth technology basics. https://www.bluetooth.com/what-is-bluetoothtechnology/bluetooth-technology-basics. Access 2016/3/5. Chen, L., Y. Chen, Y. Kuo and W. Tsai. 2015. A comparison study on water-saving effects and cut flower quality of Eustoma cultivated in furrow and micro-irrigation conditions. Taichung District Agricultural Research and Extension Station. No.127:63-72. Gardner, B. R., D. C. Nielsen and C. C. Shock, 1992. Infrared Thermometry and the Crop Water Stress Index. I. History, Theory, and Baselines. Journal of Production Agriculture. 5(4):462-466. Gardner, B. R., D. C. Nielsen and C. C. Shock. 1992. Infrared Thermometry and the Crop Water Stress Index. II. Sampling Procedures and Interpretation. Journal of Production Agriculture. 5(4):466-475. Geiser, K. M., D. C. Slack, E. R. Allred, K. W. Stange. 1982. Irrigation Scheduling Using Crop Canopy-Air Temperature Difference. Transactions of the ASAE. 25 (3): 0689-0694. Hsieh, M. H., E. C. Liu, H. C. Hsu, W. J. Jiang and J. Y. Chung. 2010. Study on Drip Fertigation Used in Greenhouse Cherry Tomato Production. Research Reports of Tainan District Agricultural Research and Extension Station. No.59:45-53. Idso, S. B., R. J. Reginato, R. D. Jackson, P. J. PinterJr. 1981. Measuring yield-reducing plant water potential
IFAC AGRICONTROL 2016 386 Gu-Zhah Hong et al. / IFAC-PapersOnLine 49-16 (2016) 381–386 August 14-17, 2016. Seattle, Washington, USA
depressions in wheat by infrared thermometry. Irrigation Science. 2(4): 205-212 Idso, S. B., R. J. Reginato, D. C. Reicosky and J. L. Hatfield. 1981. Determining Soil-Induced Plant Water Potential Depressions in Alfalfa by Means of Infrared Thermometry. Agronomy Journal, 73(5):826-830. Jou, L., Y. Chiu, and L. Fan. 2015. Designing the Universal Type of Drip Irrigation Controller for Suitably Implemented on Irrigation Requirement and Management of Pot Plants in Greenhouses. Journal of Taiwan Agricultural Engineering. 61(2):28-46 Kim, Y., R. Evans. W. Iversen. and F. Pierce. 2006a. Instrumentation and control for wireless sensor network for automated irrigation. 2006 ASABE Annual International Meeting. Paper number: 061105 Kim, Y., R. Evans. W. Iversen. and F. Pierce. 2006b. Evaluation of Wireless Control for Variable Rate Irrigation. 2006 ASABE Annual International Meeting. Paper number: 062164 Lee, W., T. Burks, and J. Schueller. 2002. Silage yield monitoring system. ASAE Annual Meeting, paper No. 021165 Wang N., N. Zhang, and M. Wang. 2006. Review: Wireless sensors in agriculture and food industry—Recent development and future perspective. Computers and Electronics in Agriculture 50 (2006) 1–14.
391