Nozzle Fuzzy Controller of Agricultural Spraying Robot Aiming Toward Crop Rows

Transcription

1 Nozzle Fuzzy ontroller of Agriultural Spraying Root Aiming Toward rop Rows Jianqiang Ren Department of omputer, Langfang Teahers ollege, Langfang, Heei Provine, P.R. hina , Tel.: Astrat. A novel nozzle ontroller of spraying root aiming toward rop-rows ased on fuzzy ontrol theory was studied in this paper to solve the shortomings of existing nozzle ontrol system, suh as the long regulation time, the higher overshoot and so on. The new fuzzy ontroller mainly onsists of fuzzifiation interfae, defuzzifiation interfae, rule-ase and inferene mehanism. onsidering the atual appliation, the fuzzy ontroller was designed as a - inputs&1-output losed-loop system. The inputs are the distane from nozzle to rop row and its hange rate, the output is the ontrol signal to the exeution unit. Based on the design projet, we seleted the FM hip NLX30, the EMU hip AT89S5 and the EEPROM hip AT9357 to make the fuzzy ontroller. Experimental results show that the projet is workale and effiient, it an solve the shortomings of existing ontroller perfetly and the ontrol effiieny an e improved greatly. Keywords: nozzle, fuzzy ontroller, spraying root, rop-rows. 1 Introdution The automation and intelletualization of the farmland working assignment is the development trend of today agriulture, the appliation of agriultural root will redue the agriultural laor intensity and raise the work effiieny greatly. The spraying root is a type of intelligent agriultural implement. The onventional spraying root adopts the overlapped spraying tehnology(ui Jun et at., 006), whih an effetively solve the prolem of leak spray ut an lead to the serious onsequenes easily, suh as the waste of pestiide resoures, the unattainment of pestiide residues in agriultural produts, the environmental pollution and so on. The preision pestiideappliation tehnology has eome one of the researh diretions of preision agriulture (Ma Hui, 00, Fu Zetian et at., 007). A pestiide system spraying with hangeale quantity ased on fuzzy ontrol was studied y Anhui Agriultural University (Shao Lushou et at., 005). The automati target deteting eletrostati air assisted orhard sprayer was designed y hina Agriultural University and hinese Aademy of Agriultural Mehnization Sienes (He Xiongkui et al., 003). The orresponding author. D. Li and. Zhao (Eds.): TA 009, IFIP AIT 317, pp , 010. IFIP International Federation for Information Proessing 010

2 Nozzle Fuzzy ontroller of Agriultural Spraying Root Aiming toward rop Rows 199 preision sprayer for site-speifi weed management was studied y the Davis Branh, alifornia University of United States (Tian L. et al., 1999). Preision and spraying system with mahine-vision guidane and adjust ale yaw nozzles was studied y Giles D.K. and Slaughter D.. (Giles D.K. et al., 1997). The spray ontrol system to aim toward rops rows ased on mahine vision was studied y Nanjing Agriultural University (Rao Honghui et at., 007). In these works, the spray ontrol to aim toward rops rows is an important tehnology in the farmland working and the nozzle was moved to aim toward rop rows aurately y a step motor. But to the existing nozzle ontrol system has shortomings, suh as the long regulation time, the higher overshoot and so on. To solve these prolems, a new nozzle ontroller ased on fuzzy ontrol theory was proposed in this paper and the ontrol effiieny was greatly raised. Struture of Spraying Root The Struture of the spraying root is shown in Fig.1. It mainly onsists of the right amera, the left amera, the spray lane, the ultrasoni ranging devie, the nozzles, the lifting gear, the root ody and the pedrails Right amera ---Left amera 3---Spray Lane 4---Ultrasoni Ranging Devie 5---Nozzles 6---Lifting Gear 7---Root Body 8---Pedrails Fig. 1. Struture of the spraying root The left amera and the right amera are used to make images of the rops. Based on these images, the rop rows an e deteted and the distane etween the rop rows and the entral axis of root an e alulated using stereosopi vision algorithm (Rao Honghui et at., 007). The ultrasoni ranging devie is used to measure the distane etween the nozzle poles and it is onsisted of one ultrasoni transmitting devie and two reeiving devies, the transmitting devie sits on the entral axis and the reeiving devies sit on the top of the nozzle poles. The spray lane (1meter long) is used to sustain the nozzles and nozzle ontrol systems. Eah nozzle is equipped with a fuzzy ontrol system whih is in the spray lane and the nozzle ontrol system is onsisted of differene alulator, fuzzy ontroller (ased on FM Fuzzy Miro ontroller) hip), exeution unit, drive iruit, stepper motor and transmission gear. The struture of the nozzle ontrol system is shown in Fig.. The differene alulator an reeive the distane ( d 0 ) from a rops row to the entral axis of root and the distane ( d 1 ) from the orresponding nozzle to the entral axis, then alulate their differene value ( ed ). The fuzzy ontroller an reeive ed as input and produe the

3 00 J. Ren ontrol signal to the exeution unit ased on fuzzy ontrol theory. The exeution unit and the drive iruit are used to produe the speifi ontrol signal to stepper motor aording to the value of, the asolute value of represents the rotation speed of stepper motor and the sign of represents the rotation diretion. The stepper motor and the transmission gear are used to adjust the position of the nozzle in order to aim toward the rop row. Distane From rops Row To entral Axis ( d 0 ) Distane From Nozzle To entral Axis ( d 1 ) Differene alulator ed Fuzzy ontroller (ased on FM) Nozzle Transmission Gear Stepper Motor Drive iruit Exeution Unit Fig.. Struture of the nozzle ontrol system In the ourse of the ontrol, the stepper motor is the final ontrolled ojet, so the mathematial model of the stepper motor is very important. Duan and Yang studied the mathematial model of the stepper motors in their paper (Duan Yinghong et at., 006). To e on the distint side, the mathematial model is introdued simply as follows. The differential equation of the stepper-motors mathematial model is as follow dia dt ua Ra 0 0 ia Laa La La L L L i di aa a a a d u R i La L L θ La L L i = 0 0 = + dt θ (1) dt u 0 0 R i La L L di La L L i dt The transfer funtion of the stepper motor dedued as follows To simplify, we an ignore the self-indutanes and the mutual-indutanes. Under the assumption of T 1 = 0 and a---a phase sequene, the motion equation of stepper motor is as follows d θ dθ Z r L1ia J + D sin Z rθ = 0 (3) d t dt If the rotor arrives at the equilirium position when t = 0, the transfer funtion of the stepper motor an e further dedued ased on the onditions stated aove and it is as follows θ ( s) Z r L1i a / J G( s) = = θ s D 1( ) (4) S + S + Z r L1i a / J J Where: Z r is the teeth numer of stepper motor. L 1 is the indutane. i a is the phase eletri urrent. J is the rotational inertia. D is the oeffiient of visosity. ()

4 Nozzle Fuzzy ontroller of Agriultural Spraying Root Aiming toward rop Rows 01 3 Design of Fuzzy ontroller 3.1 Overall Design of the Fuzzy ontroller onsidering the atual appliation, the fuzzy ontroller is designed as a -inputs&1- output losed-loop system. The first input is ed (in entimeters), the seond one is the hange rate of ed (reorded as ed ' ) (in entimeters/seond) and the output is. As mentioned aove, the asolute value of represents the rotation speed of stepper motor and the sign of represents the rotation diretion. The struture of the nozzle ontroller is shown in Fig.3. In the ontroller, the original inputs ( ed and ed ' ) are tuned to e d and e d ' firstly,and K ed, K ed ' are the proportional gains for tuning via saling universes of disourse of inputs. Then e d and e d ' are quantified to the fuzzy linguisti variales ( ed and ed ' ) y the fuzzifiation interfae. The inferene mehanism an reeive e d and e d ', determine the extent to whih eah rule is relevant to the urrent situation as haraterized y e d and e d ', and draw onlusion ( ) using the previous inputs and the information in the rule-ase (Kevin M. P., 001, P60-66 ). The defuzzifiation interfae and the output saling gain K are used to onvert the fuzzy linguisti variale into the atual output. Fig. 3. Struture of the fuzzy ontroller 3. Tuning via Saling Universes of Disourse In order to enhane the effiieny of the fuzzy ontroller, we an tune the universe of disourse for inputs and output in the ourse of design. In this papae, the spraying root has three nozzles and the first input is ed, so the effetive universe of disourse for ed is set to [-33.3,+33.3] entimeters. The tuned universe of disourse for e d is seleted as E d = [ 3, + 3 ] and the input saling gain K ed = The seond input is ed ' and its value depends on the atual rotation speed of the stepper motor, the parameters of the transmission gear and some other speifi fators. In this paper, taking universality into aount, its effetive universe of disourse is set to entimeters/seond, its tuned universe of disourse for e d ' is seleted as E d ' = [ 3, + 3 ] and the input saling gain 6 K ed ' =. β α

5 0 J. Ren The output is the ontrol signal to the exeution unit and its value depends on the atual fators too, its effetive universe of disourse is set to [ μ, ν ] in this paper. The tuned universe of disourse for is also seleted as and the input saling gain 6 K =. ν μ 3.3 Fuzzy Quantifiation of Inputs and Output In the fuzzy ontroller, the fuzzifiation interfae is used to onvert the inputs e d and e d ' into their linguisti variales so that they an e interpreted and ompared to the rules in the rule-ase and the defuzzifiation interfae is used to onvert the onlusions reahed y the inferene mehanism into the output. ed, ed ' and are the linguisti variales orresponding to the inputs and output and their linguisti values set are all the set of {NB, NM, NS, NZ, PS, PM, PB}. Their memership funtions are shown in Fig.4. NB NM NS NZ PS PM PB ed / ed ' / Fig. 4. Memership funtions of the inputs and output 3.4 Design of Rule-Base and Inferene Mehanism The rule-ase is the foundation of fuzzy inferene and it ontains a set of rules, whih are the knowledge of how est to ontrol the nozzle system and how to ontrol the system without outside help. In this paper, taking into aount the information from a human deision maker who performs the ontrol task, the rule-ase array that we use for the nozzle ontroller is designed as Tale 1. Tale 1. Rule-Base for fuzzy nozzle ontroller ed ed NB NM NS NZ PS PM PB NB PB PB PB PB PM PS PS NM PB PB PS PS PS PS NZ NS PB PM PS PS NS NM NB NZ PB PM PS NZ NS NM NB PS PM PS PS NS NS NM NB PM PS PS PM PB PM PS NZ PB PM PB PB PB NM NB NB

6 Nozzle Fuzzy ontroller of Agriultural Spraying Root Aiming toward rop Rows 03 The inferene mehanism is used to emulate the expert s deision making in interpreting and applying knowledge aout how est to ontrol the nozzle system. In this paper, the Mamdani inferene method is used to realize the fuzzy inferene and the fuzzy impliative relation as follows μ ( z) = = V{[ μ = {V[ μ Δ = ( ω V[ μ x X y Y x y Y X x X Λω ( x)) ( x)) ( x)) ) ( z) ( y)] Λ[ μ ( y)] Λ[ μ ( x)] Λ V[ μ y Y ( x) ( x) ( y) ( y) ( z)] ( y)]} ( z) ( y)]} ( z) (5) Where: is the adaptive degrees of of to '. to. ' is the adaptive degrees 3.5 Seletion of Defuzzifiation Method The defuzzifiation interfae is used to onvert the onlusions of the inferene mehanism into the atual output through a defuzzifiation method. In this paper, we use the enter-average method and the proess of defuzzifiation is shown in Fig.5. μ ( ) μ max ( ) 1 μ max ( ) 0 1 Fig. 5. The proess of defuzzifiation Where: is the atual output and it is given y μ 1 μ 1 max 1 max ( ) + μ ( ) + μ max max ( ) ( ) = (6) 4 Implementation of Fuzzy ontroller The fuzzy ontroller an e implemented ased on FM (Fuzzy Miro ontroller), and NLX30 hip is seleted as FM in this paper. NLX30 is a typial FM hip

7 04 J. Ren produed y NeuraLogix, it has 40pins in DIP pakage, and its input and output are all 8-its of digital data. The uilt-in 4-it rule register an store 64 rules at most and the maximum inferene speed is 30M rules/seond (Huang Xiaolin et at., 006). The internal struture of NLX30 is shown in Fig.6. Output Feedak 8-it Iutput Fuzzy Input seletseletor Fuzzifier A Fuzzifier B Fuzzifier Fuzzifier D Fuzzifier E Fuzzifier F Fuzzifier G Fuzzifier H Fuzzifier I Fuzzifier J Fuzzifier K Fuzzifier L Fuzzifier M Fuzzifier N Fuzzifier O Fuzzifier P Minimum omparator Maximum omparator Output R egister Rule Register Time ontrollort 8-it Output Fig. 6. Internal struture of NLX30 In this paper, the onnetion of fuzzy ontroller iruit is shown in Fig.7. The MU AT89S5 is used to ontrol all the NLX30 hips. In the initialization of system, the pins of P1.0-P1. of AT89S5 provide signals to ontrol and synhronize all the NLX30 hips. When the RST signal eome effetive, NLX30 will generate the signal of SK and S to AT9357 and reeive the rules data from AT9357. AT9357 is a K EEPROM (Wang xingzhi, 004, P ) used to store the rules data. In work proess, NLX30 reeive the input ed through DI0-DI7 and produe the output through DO0-DO7. ed DI0 DI7 DO0 DO7 To other ontrollers P1.0 P1.1 P1. AT89S5 RST NLX30 SK S DI DO LK S DO DI AT9357 Fig. 7. onnetion diagram of fuzzy ontroller iruit 5 Experiment and Analysis In order to testify the performane of the proposed sheme, the experiment was arried out and the 57BYG4503 stepper moter was seleted in it. The driving voltage of

8 Nozzle Fuzzy ontroller of Agriultural Spraying Root Aiming toward rop Rows 05 the 57BYG4503 is 36V, the phase urrent is 1.5A, the phase indutane is.4mh, the rotational Inertia is 0.3 Kg m, the teeth numer is 50 and the the stepping angle is 1.8. In the experiment, the proposed ontrol projet was ompared with the traditional ontrol methods. The experimental results show that the proposed projet has exellent ontrol effet and aility of anti-jamming. 6 onlusion A novel nozzle ontroller of spraying root aiming toward rop-rows ased on fuzzy ontrol theory was studied in this paper and the aim of this work was to solve the shortomings of existing nozzle ontrol system, suh as the long regulation time, the higher overshoot and so on. In our design projet, the fuzzy ontroller mainly onsists of the fuzzifiation interfae, the defuzzifiation interfae, the rule-ase and the inferene mehanism. The proportional gains were used to tune the universe of disourse for inputs and output. The fuzzifiation interfae is used to onvert the inputs into their linguisti variales so that they an e interpreted and ompared to the rules in the rule-ase and the defuzzifiation interfae is used to onvert the onlusions reahed y the inferene mehanism into the output. The inferene mehanism is used to emulate the expert s deision making in interpreting and applying knowledge aout how est to ontrol the nozzle system. In our Implementation projet, we seleted the FM hip NLX30, the EMU hip AT89S5 and the EEPROM hip AT9357. The experimental results show that the projet is workale and effiient, and the ontrol effiieny an e raised greatly. Aknowledgements Funding for this researh was provided y Heei Provinial Department of Eduation (P. R. hina) and the projet numer is Referenes Jun,., Baijing, Q., Jun, Z.: Researh on Overlap and Leak Spray of Spraying Root. Journal of Agriultural Mehanization Researh (1), (006) Hui, M.: hina should vigorously develop the preision of pestiide appliation tehnology 41(6), 47 (00) Zetian, F., Lijun, Q., Junhong, W.: Developmental Tendeny and Strategies of Preision Pestiide Appliation Tehniques. Transations of the hinese Soiety for Agriultural Mahinery 38(1), (007) Lushou, S., Zhixiang, D., Huailei,., et al.: Study on a Pestiide System Spraying with hangeale Quantity Based on Fuzzy ontrol. Transations of the hinese Soiety for Agriultural Mahinery 36(11), (005) Xiongkui, H., Kerong, Y., Jingyu,., et al.: Design and testing of the automati target deteting, eletrostati, air assisted, orhard sprayer. Transations of the SAE 19(6), (003)

9 06 J. Ren Tian, L., Reid, J.F., Hummel, J.W.: Development of preision sprayer for site-speifi weed management. Transations of the ASAE 4(4), (1999) Giles, D.K., Slaughter, D..: Preision and spraying with mahine-vision guidane and adjust ale yaw nozzles. Transation of the ASAE 40(1), 9 36 (1997) Honghui, R., hangying, J.: Study on spray ontrol to aim toward mahine vision. Journal of Nanjing Agriultural University 30(1), (007) Yinghong, D., Shuo, Y.: Fuzzy-PID ontrol of stepping motor. omputer Emulation 3(), (006) Passino, K.M., Yurkovih, S.: Fuzzy ontrol [Photoprint edition]. Tsinghua University Press, Beijing (001) Xiaolin, H.: Researh on NLX30 fuzzy ontroller and its emedded appliation. Foreign eletroni omponents (3), 16 1 (006) Xingzhi, W., Aiqin, Z., Lei, W., et al.: Priniple and Interfae Tehnology of AT89 series Single hip Proessor. Press of Beijing University of Aeronautis and Astronautis, Beijing (004)