Gardening Robot

7/21/2019 Gardening Robot

1/92

Master-Thesis

Gardening Robotics

Design of a Seed-Planting Robot for theCreation of Large-Scale Growing Flower

Images

Spring Term 2011

Supervised by: Authors:

Dr. Cedric Pradalier !SL " Stefan RiesenDr. Pa#l $eardsle% DR& Lin#s RohrerDr. 'o(ciech Mat#si) DR&


2/92

Contents

Abstract

Abstract (German)

ist o! "igures

ist o! Tab#es

$re!ace

1 %ntroduction

iii

v

vii

i&

&i

1


3/92

*.* Pro(ect Goals and Re+#irements . ........ . . . . . . . . . . . **.*.* ,rganiation . . . . . . . . ........ . . . . . . . . . . .

**.*. Seed /ro/erties . . . . . . . ...... .. .

. . . . . . . . . . *. Related 'or) . . . . . . . . . . . . ........ . . . . . . . . . . . 0

*..* Robotics in !gric#lt#re and 1ortic#lt#re . . . . . . . . . . .0*.. Seed Deli2er% S%stems . . . ... ... ... . . . . . . . . . .0*..0 Creation of Flower Images . ......... . . . . . . . . . . 3

2 Seed 'e#ivery System

.* $asic Princi/les . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.*.* Selection Princi/le . . . . . . . . . . . . . . . . . . . . . . . .

4.*. Deli2er% Princi/les . . . . .

. . . . . . . . . . . . . . . . . . .5.*.0 Placement Princi/les . . . .

. . . . . . . . . . . . . . . . . . . 6. Conce/t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

..* Seed Selection Mechanism . . . . . . . . . . . . . . . . . . . .7.. 8(ection Mechanism . . . .

. . . . . . . . . . . . . . . . . . . 9.0 8ngineering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . *:

.0.* Selection Mechanism . . . . . . . . . . . . . . . . . . . . . . . *:.0. 8(ection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . *:

.3 8;tendabilit% and Possible Im/ro2ements . . . . . . . . . . . . . . . *3.3.* More Seed T%/es . . . . . . . . . . . . . . . . . . . . . . . . . *3.3. Sensors on the Sliders . . . . . . . . . . . . . . . . . . . . . . *3

*+,Tab#e !or Ti#ing 1

0.* Conce/t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . *40.*.* S#bstrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . *40.*. Gl#e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . *4

0. 8ngineering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . *60..* Mechanical Design . . . . . . . . . . . . . . . . . . . . . . . . *60.. 8lectronic S%stem . . . . . . . . . . . . . . . . . . . . . . . . *7

0.0 Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . :0.0.* Gra/hical


4/92

4.3 Re+#ired Com/onents and Sie 8stimation . . . . . . . . . . . . . . 064.3.* ,2er2iew . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 064.3. Mani/#lator . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3:

4.4 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3:4.4.* Pose 8stimation . . . . . . . . . . . . . . . . . . . . . . . . . 3:4.4. Planting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3:4.4.0 Path Planning . . . . . . . . . . . . . . . . . . . . . . . . . . 3

4.5 !2ailable Platforms . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

/ Conc#usion and ut#oo -

5.* Concl#sion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345. ,#tloo) and F#t#re 'or) . . . . . . . . . . . . . . . . . . . . . . . . 34

5..* 8ngineering of the Mobile Platform . . . . . . . . . . . . . . 345.. Grass seeding . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

A 'atasheets -

3 Test Resu#ts

C Content o! the '4' /

3ib#iography /5

ii


5/92

Abstract

This /ro(ect deals with the de2elo/ment of a robot that is able to /lant a small n#mber ofseeds of diferent s/ecies at /redefined /ositions for the creation of growing >ower images.For this /#r/ose a seed deli2er% s%stem that is able to select deli2er and /lace the seeds wasengineered. This mechanism has been integrated into a Cartesian robot which can /lant a tile

of one s+#are meter on a trans/ortable s#bstrate. It %ields the /ossibilit% to /re/are the >owerimages inde/endentl% of the time and location of the final de/lo%ment.The seed deli2er% s%stem consists of fi2e dis/enser mod#les that can select a s/ecified amo#ntof seeds from a seedbo;. 8ach mod#le is ada/table to the seed form and sie thro#gh ane;changeable o/ening mechanism. More mod#les can be added easil% to f#rther increase the/erformance. !n air /ress#re based deli2er% shoots the seeds from the dis/enser mod#les tothe e(ection s#bs%stem thro#gh a /lastic t#be. ! sensor s%stem was added at the o#tlet todetect whether a seed has been /laced correctl% or not in order to close the control loo/.The Cartesian stage is assembled as an 1-config#ration with tooth-belted a;es and electricalmotors o/erated at 3?DC. !s the mani/#lator onl% needs to carr% the e(ection s#bs%stemand the deli2er% t#be the /ower demands on the motors are relati2el% low. F#rther a controlsoftware and #ser interface was written for both Microsoft 'indows and Lin#;. For theLin#; software a node in the robot o/erating s%stem @R,SA framewor) has been

im/lemented.The /erformance of the s%stem has been tested e;tensi2el% for reliabilit% /recision andre/eatabilit% with seeds of diferent sies and forms. It has been obser2ed that the n#mber ofe(ected seeds 2aries onl% within the s/ecified tolerance. Concerning the /recision there+#irements were also f#lfilledB 56 of all seeds were /laced within one centimetre and74 were detected in a radi#s of *.4cm from the reference /oint. F#rther the /erformance ofthe e(ection sensor has also been e2al#ated. !ll seeds were reliabl% detected es/eciall% forlarge seed sies or high n#mbers of e(ected seeds.Finall% a conce/t for a mobile robot which can /lant >ower images a#tonomo#sl% wasde2elo/ed. ! similar mani/#lator as in the static sol#tion is intended to be #sed. Se2erallocomotion and localiation conce/ts ha2e been e2al#ated and it is /ro/osed to #se adiferential dri2e /latform combined with laser based triang#lation. !s obser2ed in first

sim#lations the /recision of the /ose estimate co#ld be f#rther increased b% adding acom/ass.

6ey7ords:Gardening Robotics Flower Images Seed Deli2er% S%stem CartesianRobot !#tonomo#s Mobile Robot

iii


6/92

i2


7/92

Abstract

Das &iel dieser !rbeit ist die 8ntwic)l#ng eines $e/>an#ngsroboters der $l#men- samen2erschiedener !rten in einem 2ordefinierten M#ster seten )ann. Dad#rchwird es erm ht ein beliebig grosses $l#menbild # erstellen. 8in Mechanism#s oglicder einelne Samen a#s einem $eh alter a#sw ahlen #nd # einem !#slass trans-

/ortieren )ann w#rde da# entworfen. an#ng 2orbereiten # ) onnen w#rde der Mechanis-m#s in einen E-Tisch integriert wobei die Samen a#f eine wasserl he Folie 2on oslic(e einem #adratmeter Fl he /latiert werden. Die Folie )ann danach a#f dem acFeld a#sgelegt #nd bew assert werden.Das S%stem besteht a#s f Dis/enser-Mod#len die (eweils eine bestimmte Menge #nfan Samen a#s einem $eh alter a#sgeben. Die Mod#le ) onnen der Form #nd Gr osseder # />anenden Samen ange/asst werden indem der ,fn#ngsmechanism#s a#s- gewechselt wird. 'eitere Mod#le ) onnen leicht hin#gef werden #m die F#n)- #gttionalit # erweitern. Die Samen werden d#rch ein L#ftdr#c)s%stem 2on den atDis/enser-Mod#len # einem !#slassmechanism#s bef ordert wo ein Sensors%stemangebracht w#rde #m die )orre)te !#sgabe # er/r

#b #fen #nd dad#rch den Regel-

)reis # schliessen.Der )artesische Roboter w#rde als 1-Portal bestehend a#s &ahnriemenachsen #nd 3?Gleichstrommotoren realisiert. Da die bewegte Masse n#r a#s dem !#slasss%s-tem #nd dem f #hrschla#ch besteht sind die Leist#ngsanforder#ngen an die Mo-toren relati2 gering. Ferner w#rde eine Ste#er#ngs-Software #nd eine $en#ter-ober> he sowohl f Microsoft 'indows wie a#ch f Lin#; /rogrammiert. Die

ac #r #rLin#;-Software w#rde als =ode im Robot ,/erating S%stem @R,SA Framewor)im/lementiert.Die erl assig)eit Pr aision #nd 'iederholbar)eit des S%stems w#rde a#sgiebigmit Samen 2erschiedener Gr ossen #nd Formen #nters#cht. Dabei eigte sich dassdie !nahl der /latierten $l#mensamen n#r innerhalb der 2orgegebenen Toleran

2ariiert. Im $e#g a#f die Pr aision )onnten die !nforder#ngen ebenfalls erf #lltwerdenB 56 aller Samen w#rden in einem anen )ann. Der Mani/#lator a#s der statischen L os#ng)ann mit leichten ?er ander#ngen ernommen werden. ?erschiedene Fortbewe- #bg#ngs- #nd Lo)alisier#ngs)one/te w#rden e2al#iert #nd es wird 2orgeschlagen einePlattform mit einem diferentiellen !ntrieb # 2erwenden. r Lo)alisier#ng )ann Laser-Triang#lation in ?erbind#ng mit einem Hom/ass #nd der ,dometrie einge-sett werden. 'ie erste Sim#lationen eigten )ann dad#rch eine hohe Pr aisionerreicht werden.

Stich7orte:$e/>an#ngsroboter $l#menbilder E-Tisch !#tonomer mobilerRoboter

2


8/92

2i


9/92

ist o! "igures

.* ?ac##m /robe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.Slider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.0 Slider with

limited o/ening 2ol#me . . . . . . . . . . . . . . . . . . .9.3 Slider withlimited o/ening 2ol#me and control /ress#re t#be . . . .

9.4 Seeddeli2er% mod#le for m#lti/le seed t%/es . . . . . . . . . . . . . **.5 Rela% dri2er . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . *.6 Seed e(ection mechanism . . . . . . . . . . . . . . . . . . . . . . . . . *0.7 8(ection sensor schematic . . . . . . . . . . . . . . . . . . . . . . . . *3

0.* E-Table @,2er2iewA . . . . . . . . . . . . . . . . . . . . . . . . . . *70. E-Table s%stem schematics . . . . . . . . . . . . . . . . . . . . . . *90.0 Gra/hical #ser interface . . . . . . . . . . . . . . . . . . . . . . . . . *0.3 Planting /rocess >owchart . . . . . . . . . . . . . . . . . . . . . . . . 0

3.* Test set#/ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53. =#mber of e(ected seeds . . . . . . . . . . . . . . . . . . . . . . . . . 63.0 Position of e(ected ?iola seeds . . . . . . . . . . . . . . . . . . . . . . 73.3 Position of e(ected Phlo; seeds . . . . . . . . . . . . . . . . . . . . . 73.4 Position of e(ected Im/atiens seeds . . . . . . . . . . . . . . . . . . . 73.5 Position of e(ected seeds from all meas#rements . . . . . . . . . . . . 93.6 PrecisionRecall of the e(ection sensor . . . . . . . . . . . . . . . . . 0:

4.* Terrain constraints . . . . . . . . . . .. .. .. .. .. . . . . . . . . 04. ,2er2iew of the mobile /latform . . .. .. .. .. .. . . . . . . . . 094.0 R,S-=ode str#ct#re for the control of the mani/#lator . . . . . . . . 34.3 Path /lanning . . . . . . . . . . . . . .. ... .... . . . . . . . . . 30


10/92

2ii


11/92

2iii


12/92

ist o! Tab#es

0.*

3.*

4.*4.4.0

S#bstrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8(ection sensor /erformance . . . . . . . . . . . . . . . . . . . . . . .

Localiation methods s#mmar% . . . . . . . . . . . . . . . . . . . . . Re+#iredcom/onents . . . . . . . . . . . . . . . . . . . . . . . . . . Position control algorithm/arameter descri/tion . . . . . . . . . . .

*5

9

07093*

$.* Seeding test res#lts for Im/atiens Slider S . . . . . . . . . . . . . . . 46$. Seeding test res#lts for ?iolas Slider S . . . . . . . . . . . . . . . . . 49$.0 Seeding test res#lts for ?iolas Slider M . . . . . . . . . . . . . . . . 5*$.3 Seeding test res#lts for Phlo; Slider M . . . . . . . . . . . . . . . . 50$.4 Seeding test res#lts for Phlo; Slider L . . . . . . . . . . . . . . . . . 54

i;


13/92

;


14/92

$re!ace

This MasterJs thesis concl#des o#r st#dies in Robotics S%stems and Control at theSwiss Federal Instit#te of Technolog% in & h. The /ro(ect is a coo/eration be- #rictween the !#tonomo#s S%stems Lab @!SLA and Disne% Research & h @DR&A and #ricdeals with the robotic creation of a large-scale >ower image. Growing images are widel%

#sed as a decoration element of o#tdoor areas s#ch as cit% gardens ro#nd- abo#ts aro#nd/#blic b#ildings as well as in am#sement /ar)s. S#ch images are created man#all% and ha2etherefore high labo#r costs and limited 2is#al efects. 'ith an a#tonomo#s robot this cost canbe minimied and the image com/le;it% increased. This a//lication has commercial /otentialfor o#tdoor ad2ertisements and as an attraction for am#sement /ar) 2isitors.

D#e to the di2ersit% of challenges this has been a 2er% interesting /ro(ect and wewish to than)

KProf. Dr. Roland Siegwart for gi2ing #s the o//ort#nit% to cond#ct this /ro(ectat the !#tonomo#s S%stems Lab.

K,#r s#/er2isors Dr. C" edric Pradalier at !SL Dr. Pa#l $eardsle% and Dr. 'o(-ciech Mat#si) at Disne% Research for their s#//ort and the enco#raging dis- c#ssions.

K!ll other /eo/le directl% afliated with the /ro(ect for the ins/iring disc#s-sions and the insight into their /artsB Dr. Dere) $radle% Dr. Fran) Liebisch Dr.=orbert Hirchgessner and Dr. Robert 'ang.

KThe IT-s#//orters Stefan $ertschi and Thomas $a#mgartner for their s#//ortin administrati2e IT-related and electronics-related +#estions.

KThe mechanic technicians Mar)#s $ #hler and Dario Fenner for the man#fac-t#ring of the mechanical /arts and s#//ort in related +#estions.

K!ll members of !SL and DR& for their hel/ in +#estions related to theirs/ecific fields of research.

K!nd last b#t not least o#r friends and families for their great s#//ort andenco#ragement d#ring both this /ro(ect and the entire st#dies.

Z urich, August 2011

Stefan Riesen and Linus Rohrer

;i


15/92

;ii


16/92

Chapter 1

%ntroduction

181 $ro9ect Goa#s and Reuirements

The o2erall goal of the Disne% Flower Images Pro(ect is to grow a bed of >owers with thea//earance of a realistic image. Flower images are alread% fo#nd in cit% /ar)s b#t the% arecreated man#all% which is time-cons#ming and limits the 2is#al efects. $% a#tomating the/rocess it is aimed to achie2e more so/histicated res#lts. This thesis is foc#sed on therobotics com/onent of the /ro(ect and the goal is to ma)e a seed-/lanting robot. Two2ariants of the robot are to be de2elo/ed. The first is a stationar% robot which can /lant seedsonto a tile of one s+#are meter. The second 2ariant is a f#ll% a#tonomo#s mobile robot whichcan /lant directl% in an o#tdoor setting with 2ariable field sies. $oth robots shall be able tohandle a wide range of /lant seeds whereas diferent seeds can be #sed sim#ltaneo#sl%. Thecreation of an o/timied >ower /attern gi2en from an in/#t image was not in the foc#s ofthis thesis and is considered to be a2ailable as an in/#t to the s%stem.

18181 rgani;ation

The /ro(ect is organied in three engineering stages. These are not entirel% de/en-

dent on the res#lts of the /re2io#s stage and can therefore be de2elo/ed conc#rrentl%.

Stage 1: 'eve#opment o! a Seed 'e#ivery System

In the first stage a seed deli2er% s%stem for the s/ecified seed t%/es @See section *.*.A

is to be de2elo/ed. The mechanism shall be able to select a defined amo#nt of seeds anddeli2er them to an o#tlet where the% are /laced. The selection mechanism is re+#ired to bedesigned in wa% that the seeds can be selected from m#lti/le seed t%/es either diferentcolo#rs of the same s/ecies or diferent s/ecies. ! )e% /oint is the reliabilit%B It is im/ortantthat the n#mber of seeds selected and deli2ered does not ha2e a high 2ariance and that thea2erage n#mber of seeds corres/onds to a /redefined n#mber. This n#mber ma% 2ar%between s/ecies. The desired e(ection /recision is that most seeds are in a range of*.4cmfrom the reference /oint. The seed deli2er% mechanism has to be designed in a wa% to beo/erated in one of thefollowing modesB

KM#lti/assB The robot /asses the field m#lti/le times with another seed t%/eeach time. $etween the /asses it is re+#ired to e;change or refill the seedbo;.

KSingle/assB The robot /asses the field onl% once seeding all seed t%/es in this/ass. The mechanism selects the correct seed t%/e from m#lti/le seedbo;es and /lacesit.

*


17/92

Cha/ter *. Introd#ction

K1%bridB The robot /asses the field m#lti/le times with a set of diferent seedt%/es each time. $etween the /asses the seedbo;es are e;changed either man#all% ora#tomaticall%.

Stage 2: %mp#ementation o! the Seed 'e#ivery System on a Stationary

2',Robot

In a second ste/ the seed deli2er% mechanism is mo#nted on a static robot which

allows the /lanting of >ower images onto a s#bstrate. This can either be a bo; of soil whichis then #sed for growing the /lants in a greenho#se and then /laced onto the field. !nalternati2e wo#ld be a bio-degradable s#bstrate which is laid o#t on the field where the/lants are directl% grown. For sim/licit% the tiles shall be as big as /ossible in order tored#ce the n#mber b#t on the other hand for eas% handling of the tiles small tiles wo#ld be/referred. Therefore the sie of one tile has been defined to one s+#are meter as it is a goodcom/romise between handiness trans/ortabilit% and a low n#mber of tiles.

Stage : %mp#ementation o! the Seed 'e#ivery System on an Autonomous

$#at!orm

To allow the f#ll% a#tonomo#s creation of large-scale growing >ower images an

a#tonomo#s mobile robot is to be de2elo/ed in the third stage. The robot shall be e+#i//edwith a mani/#lator based on the seed deli2er% s%stem de2elo/ed in the first stage. F#rther therobot has to be able to localie itself with a s#itable algorithm and to /lan the /ath on thefield a#tonomo#sl%. If for an% reason the achie2ed /ositioning /recision of the robot is lessthan the re+#ired /recision for /lanting the mani/#lator has to be designed in a wa% that itcan com/ensate an% mis/lacements of the robot in order to increase the /lanting /recision tothe desired le2el. This im/lies that the localiation /recision is higher than the re+#ired/lanting /recision.

18182 Seed properties

From a list of s/ecies that are considered s#itable for the creation of growing images

the seeds ha2e been anal%ed. The% were classified according to their form and sie.

KDahlia hybridsB Flat longish abo#t *;3mmKDorotheantus bellidiformisB S/herical abo#t :.*mm in diameterKa!ania hybridsB 8lli/soid abo#t :.7;mmK"m#atiens $allerianaB 8lli/soid abo#t :.4;:.7mmK%etunia hybridsB S/herical abo#t :.mm in diameter

K%hlo& drummondiiB 8lli/soid abo#t :.6;*mmK%ortulaca grandifloraB S/herical abo#t :.0mm in diameterK'erbena hybridsB 8lli/soid abo#t :.4;.4mmK'iola $ittroc(ianaB =earl% s/herical abo#t :.7mm in diameter. =oteB ?iolas

are biann#al and therefore onl% s#itable for the long-term creation of >ower images.

From the list a s#bset of s/ecies with similar form and sie class was selected to

s/ecif% the re+#irements on the robot in this stage b#t it has also been defined that theselection mechanism shall be e;tendable to other s/ecies. The selected s/ecies are 'iolas%hlo&and"m#atiens. These seeds ha2e their ro#ndish form and their a//ro;imate sieof abo#t :.4-*mm in all directions in common.


18/92

*.. Related 'or) 0

182 Re#ated ower images no e;isting /latform can be #sed or f#rther de2elo/edb#t a new one has to be designed from scratch.

18282 Seed 'e#ivery Systems

The a#tomatic deli2er% of seeds o#t of a seedbo; onto the gro#nd has been de2elo/ed +#ite

earl% in ind#strial histor%. These s%stems distrib#te the seeds in a /redefined area #singdr#ms drilling or digging de2ices b#t none of these s%stems is #sed for /recise /lacement ofa single seed to a defined /osition. !lso most of these s%stems deal with onl% one seed t%/e.=e2ertheless in the last 0: %ears some attem/ts to /ic) #/ a single seed ha2e been made.Ma#r% 6 /atented an a//arat#s where the seeds are /laced on a rotating dis) and then areshot with air /ress#re into the gro#nd when their /osition on the dis) /asses the o#t/#t2al2e. Similarl% a(i et al. *3 first #se a negati2e air /ress#re to /ic) a seed o#t of aseedbo; mo2e it to the o#tlet /osition and then a//l% a /ositi2e air /ress#re to shoot the seedinto the gro#nd.

Heller et al. f#rther de2elo/ed this /rinci/le in 5 where the seeds are /ic)ed #/

b% a /recise 2ac##m /robe and let them fall b% in2erting the /ress#re. Their robot is not #sedto /lant seeds b#t to transfer seeds from one seedbo; to another. ! diferent a//roach to

/ic) #/ a single seed is #sed b% Ton#s 9. In his /atent a needle mo2es from the gro#nd of aseedbo; to its to/. The ti/ is designed in a wa% that onl% one seed remains on it. !fterreaching the to/ of the seedbo; the ti/ enters a small t#be from where the seed on the ti/ istrans/orted to the o#tlet #sing air /ress#re.

For the a//lication of this /ro(ect there is no read%-to-#se sol#tion a2ailable b#t

se2eral sol#tions that can be #sed as a base to design a mechanism. 8s/eciall% this a//lies tothe 2ac##m /robe and to the mechanical selection combined with an air /ress#re baseddeli2er% s%stem. Those two a//roaches seem to be most /romising as a starting /oint sincethe% allow /recise selection and /lanting of single seeds. For the re#se of the 2ac##m s%stemlegal iss#es ha2e to be ta)en into consideration.


19/92

3 Cha/ter *. Introd#ction

1828 Creation o! "#o7er %mages

The creation of >ower images as #sed for decoration of gardens or /ar)s andor for

ad2ertising /#r/oses is still a man#al o/eration. Trebbin et al. *: ** ha2e started researchin this direction. The% #se the following two diferent a//roaches. The first is to /lant theseeds which form the image directl% at the corres/onding locations. The% intended to #se adrilling machine that is mo2ed b% a tractor na2igated b% the global /ositioning s%stem GPS.!s the GPS has a localiation /recision of abo#t .4m it is ass#med that a GPS located andman#all% dri2en tractor wo#ld not reach the desired /lanting /recision th#s not leading to asatisf%ing >ower image. !dditional sensors for an acc#rate /ose estimation and ana#tomaticall% dri2en 2ehicle as intended to be de2elo/ed in the third /ro(ect stage @Seesection *.*.*A are e;/ected to gi2e a significantl% better res#lt.The second a//roach is to /rint the seeds on a s#bstrate made of /ol%-2in%l-alcohol similarto the /atent b% 'ir *0. The s#bstrate is then laid on the gro#nd and co2ered with soil.$% watering the s#bstrate it dissol2es and the seeds remain in their location. This seems tobe a considerable alternati2e to /lanting on soil tiles for the second de2elo/ment stage @See

section *.*.*A. ! s#bstrate is lighter than a bo; of soil and is therefore easier to handle.F#rther the tiles can be /re/ared inde/endent of time and location of the final de/lo%mentand can be stored #ntil needed.!s Trebbin et al. *: ** ha2e withdrawn their /atent a//lication for the first a//roach it isass#med that the% foc#s on the second a//roach. =either is /#blished how the% create ano/timal >owering /attern o#t of the image to get the best sol#tion.


20/92

Chapter 2

Seed 'e#ivery System

"deas ho$ to handle a small number of seeds are discussed in thischa#ter $hereby the tas( is di)ided into the three sub#roblems

Selection, Deli)ery and %lacement. *ased on this discussion, a solution

that includes a seedbo& $ith a controllable do$n$ard o#ening and an

air #ressure based deli)ery is #resented. +inally, some theoretical

thoughts of #ossible im#ro)ements are listed.

281 3asic $rincip#es

This section describes the /ossible /h%sical efects that are considered to be #sef#l for theseed deli2er% s%stem. It is disting#ished between the tas)s Selection Deli2er% and Placement.

Princi/les were de2elo/ed for each tas) se/aratel% and then merged into the conce/tdescribed in section . below.

28181 Se#ection $rincip#e

In the selection tas) the robot or /arts of it m#st be able to select a s/ecified n#mber of adefined seed s/ecies o#t of a bo; and hand the seeds o2er to the s#bs%stem which /erformsthe deli2er% tas). This can be achie2ed b% the /rinci/les described below.

4acuum

!s ill#strated in fig .* a seed is /ic)ed #/ b% a /robe which can create a negati2e air/ress#re at its ti/. ?ac##m is widel% #sed for /ic)-and-/lace o/erations of ob(ects in 2ario#ssie classes. To select diferent seeds from m#lti/le bo;es the /robe mo2ement needs onl% tobe /rogrammed according to the /ositions of the bo;es. To hand the /ic)ed #/ seed o2er toa deli2er% mechanism a /ositi2e air /ress#re is created at the /robe to blow the seed awa%onto the deli2er% mechanism or directl% onto the /lacement /osition. This method is/atented b% Heller et al. 5 for the handling of seeds. !d2antages are that an% sie and formclass can be handled as well as the n#mber of seeds is ad(#stable b% a change of the ti/ sie.! ma(or drawbac) is the need for an additional a;is as the ti/ is re+#ired to mo2e 2erticall%for reliable /ic) #/ when the n#mber of seeds in the bo; changes. F#rther - if combined withdirect deli2er% - the /lanting time is significantl% increased since the /robe has to co2er thedistance from the /ic)-#/ to the /lanting /osition for each seeding /oint.

4


21/92

5 Cha/ter . Seed Deli2er% S%stem

/ic)ed-#/ seed

Seedbo;

Fig#re .*B ?ac##m /robe

Gravity

'hen gra2it% shall be #sed as a selection /rinci/le the seedbo; needs to ha2e a controllabledownward o/ening. This can be achie2ed with an electromagnet a motor or a /ne#matics%stem that mani/#lates the o/ening mechanism. The sim/licit% of this conce/t is a bigad2antage which leads to lower design efort and /rod#ction costs. Disad2antages are the factthat an% mo2ing /arts can be bloc)ed b% seeds and that the n#mber of selected seeds is onl%defined b% a statistical /rocess. M#lti/le seed t%/es can be easil% combined b% adding amod#le for each s/ecies. 8ach selection mechanism can be tailored to the s/ecific /ro/ertiesof the corres/onding seed.

>#ectrostatic 4a#ve

It has been obser2ed that the seeds stic) to electrostaticall% charged s#rfaces. This co#ld be#sed in combination with a /robe that has a controllable electrostaticall% chargeable s#rfaceat its ti/. 8lectrostatics ha2e alread% been #sed b% $alachandran et al. 0 in order to controlthe >ow of agric#lt#ral seeds in b#l) trans/ortation. This co#ld be ada/ted to single seedsb#t wo#ld re+#ire f#ndamental research on the electrostatic /ro/erties of diferent seeds.

.echanica# $ic,?p

et another method wo#ld be to /ic) #/ seeds with a mechanical de2ice as a gri//er. Similarto the 2ac##m /rinci/le this also re+#ires a third a;is for /ic)-#/ and /lacement. !ltho#gh

it is 2er% >e;ible for diferent seed t%/es and sies a gri//er re+#ires a 2er% /recisemechanical design in order to handle the f#ll 2ariation of diferent seeds witho#t destro%ingthem. F#rther a com/le; control str#ct#re is needed which is closel% tied to the mechanical/ro/erties and that can also s#r2e% the selected amo#nt of seeds.

28182 'e#ivery $rincip#es

In the deli2er% tas) the corres/onding /arts ha2e to deli2er the selected seeds to the/lacement mechanism. The following /rinci/les show /ossible sol#tions that can accom/lishthis /roced#re.

?ac##m/robe


22/92

.*. $asic Princi/les 6

'irect 'e#ivery

The selection mechanism is located directl% on the mani/#lator of the /lacement

mechanism. In combination with a 2ac##m /robe or a mechanical gri//er this means thatthe /robe is able to mo2e to an% /osition where a seed sho#ld be /laced. In the case of anelectrostatic 2al2e or a gra2it%-based selection mechanism the seedbo;es wo#ld also need tobe /laced on the mani/#lator. This limits the n#mber of seedbo;es that can be carried andthe mo2ing mass wo#ld be increased.

Air $ressure

The idea is that the selection s#bs%stem /ic)s #/ the seed and /laces it into a

t#be. Then air /ress#re is a//lied and the seeds are shot to the /lacement de2ice. This has thead2antage that the seedbo;es do not ha2e to be /laced on the mo2ing mani/#lator th#sred#cing the mo2ing mass and the energ% cons#m/tion. !nother ad2antage is that additionalseedbo;es e2ent#all% based on a diferent selection /rinci/le can be added to the s%stem

easil% b% e;tending the t#be.

2818 $#acement $rincip#es

This s#bs%stem has to /lace the seeds at the s/ecified /osition. The #sage of the

/rinci/le de/ends also on the seed t%/e which can either be re+#ired to lie on the gro#nd tobe slightl% co2ered with soil or to be #nder gro#nd in order to germinate. F#rther it isreasonable to add a sensor which detects whether a seed has been /laced correctl% or not.

Gravity

Gra2it% wo#ld be the sim/lest /ro/osition as it does not re+#ire a com/le; mech-

anism b#t it is onl% s#itable for seeds that are to be l%ing on gro#nd. For seeds that need to

be co2ered with soil the co2erage co#ld be a//lied man#all% or with another mani/#lator ina second ste/.

'ri##ing

!n ob2io#s wa% to bring a seed #nder gro#nd is to drill a hole with a borer or

to stri)e a hole with a rod. In both sol#tions the seed wo#ld then be dro//ed se/aratel% intothis ga/. It is re+#ired to ens#re that the hole does not fall together before the seed is /laced.Possibl% the bore has to be closed again after the /lanting of the seed. 1ence the mechanicalstr#ct#re of the mani/#lator has to be e;tended.

Air $ressure

The air /ress#re - e.g. from an air /ress#re based deli2er% - can be #sed to create alittle hole in which the seed is shot into. This re+#ires a strong air /ress#re so#rce and mightfail if the gro#nd is too hard @e.g. d#e to stonesA. !nother ris) wo#ld be that seeds alread%/laced nearb% co#ld be dis/laced b% the /ress#re e;ha#st or b% material being blown awa%.


23/92

7 Cha/ter . Seed Deli2er% S%stem

282 Concept

!s a basic conce/t a combination of the following /rinci/les was chosenB

KSelect a seed #sing gra2it% thro#gh a controllable downward o/ening in theseedbo;

KDeli2er the seed to the e(ection /ort b% a//l%ing air /ress#reK8(ect the seed directl% onto the gro#nd and detect falling seeds

The main reason for choosing these /rinci/les is their sim/licit% and cost-efecti2e-

ness. ! f#rther ad2antage of the gra2it% based selection the e;tendabilit% of the s%stem wasanother reason for this selection. The sim/licit% of the air /ress#re based deli2er% lies in thefact that it eliminates the need for a third a;is and lowers the mo2ing mass since onl% asingle t#be has to be carried.

28281 Seed Se#ection .echanismThis basic conce/t for the selection mechanism @i.e. the controllable o/eningA was

de2elo/ed and refined in three engineering iterations starting with a 2er% sim/le mechanismin the first iteration and correcting drawbac)s in the s#bse+#ent ste/s. F#rther the e(ectionwas ada/ted to red#ce the drawbac)s gi2en b% the air /ress#re deli2er% s%stem.

Simp#e S#ider

The first a//roach is a sim/le slider o/ening mechanism as shown in fig. .. 'hen

the slider is o/ened a small b#t not e;actl% defined n#mber of seeds fall o#t of the seedbo;into the g#ide. Then the slider is mo2ed forwards th#s /#shing the seeds into the deli2er%t#be and closing the o/ening. ! first hand-made f#nctional /rotot%/e ga2e good res#lts b#tthen the /recisel% man#fact#red /rotot%/e showed the critical /oint that the n#mber of seedsis not reall% limited. This ga2e a high 2ariance in the n#mber of e(ected seeds which was notdesired.

S#ider 7ith imited pening

$ased on the e;/erimental res#lts of the first iteration the o/ening 2ol#me was

limited in the second draft as shown in fig. .0. The limitation of the o/ening 2ol#meres#lted in a significantl% lower 2ariance in the n#mber of seeds that are selected. Thecorres/onding /rotot%/e was not man#fact#red as its /arts wo#ld ha2e been too com/licatedre+#iring the milling of 2er% small com/onents which wo#ld be feasible b#t com/licatedand costl%.

Seedbo;

!ir Press#re T#be

Slider

#N#: #N#ma&

Fig#re .B Slider


24/92

.. Conce/t 9

Seedbo;

!ir Press#re T#be

Slider

#N#: #N#ma&

Fig#re .0B Slider with limited o/ening 2ol#me

Seedbo;

Control Press#re #N#maN#:

Slider

Deli2er% T#be

#N#: #N#ma&

Fig#re .3B Slider with limited o/ening 2ol#me and control /ress#re t#be

>&tended S#ider

The e;tended slider mechanism as shown in fig .3 is the final design. In contrast to thesol#tion abo2e it has a 2ertical bore which allows eas% man#fact#ring. The bore is a critical/oint as the seeds ma% get st#c) in it. ,//osed to the second sol#tion the o/ening cannot becleaned b% the deli2er% /ress#re as the bore a;is is across the direction of /ress#re. Thereforea se/arate control /ress#re t#be is added which allows the slider to be cleaned before thedeli2er% /ress#re is a//lied. F#rther it is easil% ada/table to diferent seed sies as the hole

sie of the e;changeable slider can be man#fact#red with diferent diameters.

28282 >9ection .echanism

The seeds are e(ected thro#gh a 2erticall% fi;ed t#be. In this t#be small holes to red#ce theair /ress#re are integrated in order to slow the seeds down before being /laced on thegro#nd. !fter first tests it has been obser2ed that this is not s#fcient. Therefore a bloc)ingmechanism is added which sto/s the seeds com/letel% and e(ects them after the air /ress#rehas been red#ced. F#rther a light barrier s%stem is mo#nted at the e(ection /oint. This sensorcan detect whether a seed has been /laced or not to close the control loo/.


25/92

*: Cha/ter . Seed Deli2er% S%stem

28 >ngineering

2881 Se#ection .echanism

.echanica# 'esign

!fter the conce/t has been de2elo/ed the definiti2e design of the selection mech-

anism has been engineered as ill#strated in fig. .4. Since it is e;/ected that a growingimage can be created with fo#r to fi2e t%/es of diferentl% colo#red >owers there are fi2eidentical mod#les integrated into the s%stem. The main element is the gro#nd /late consistingof an #//er and a lower /art containing both the deli2er% t#be and the control t#be as well asthe g#idances for the sliders of all fi2e mod- #les. The sliders were man#fact#red with threediferent hole sies with diameters of mm 0mm and 3mm to be easil% e;changed accordingto the seed t%/e #sed in the corres/onding seedbo; and the desired n#mber of seeds to bee(ected. !ll /arts ha2e been fabricated #sing a 0D-/rinter.To close the seedbo;es a co2er and a lower clos#re ha2e been designed. The co2er

is re+#ired as there is /ress#re going from the control t#be into the seedbo;. This mi;es theseeds #/ and lowers the /robabilit% of a seed getting st#c). The onl% drawbac) is that seedsmight get blown o#t of the bo; if no co2er is #sed. ! lower clos#re is #sed for e;changing anon-em/t% seedbo;. If the o/erator wants to e;change a seedbo; the lower clos#re can beclosed man#all% and the seedbo; can be dismo#nted from the gro#nd /late.For the slider mo2ement act#ation monostable electromagnets of the t%/e Tremba1M! 5.::* o/erated at 3?DC are #sed. These magnets /#ll the le2er in when/ositi2e 2oltage is a//lied. ,nce it is in its retracted /osition it is held there b% a /ermanentmagnet. If a negati2e 2oltage is a//lied the le2er is released and shifted o#t b% the s/ring #/to an e;ternal mechanical bloc)ing de2ice. These magnets ha2e a nominal shifting distance of*0mm b#t onl% abo#t 7mm are #sed in the selection mechanism as the retracting forcedecreases dramaticall% with increasing shift. The mo2ement range is determined b% the slider

reaching the end of the g#idance in the gro#nd /late.

>#ectronica# 'esign

For controlling the electromagnets and /ress#re 2al2es an !rd#ino Mega 45: Mi-

crocontroller with a c#stom b#ilt dri2er board is #sed. To /ro2ide the needed 2olt- ages forthe electromagnets d/dt @do#ble /ole do#ble throwA rela%s were selected. Logic-M,SF8TJsresistors and diodes are needed for controlling and switching the rela%s. 8ach slidermechanism of the seed selection s%stem re+#ires its own mod#le of the abo2e describedelements. ,ne mod#le of the dri2er board can be fo#nd in fig. .5. F#rther the control of theair /ress#re 2al2es and the o/tional 2ibrating motor intended for the /re2ention of slider(amming are also integrated into the dri2er board.

2882 >9ection

.echanica# 'esign

First e;/erimental res#lts showed that the direct e(ection from the deli2er% t#be

onto the s#rface is not 2er% /recise. If the ga/ between the t#be and the s#rface is too highthe e(ected seeds get blown of b% the /ress#re e;ha#st. ,n the other hand if the ga/ is toosmall the robot cannot mo2e #nhindered and is li)el% to dislocate alread% /laced seeds.Therefore the mechanism ill#strated in fig. .6 was designed to slow down the seeds at thee(ection. In this mechanism the e(ection t#be is


26/92

.0. 8ngineering **

Co2er

Seedbo;Clos#re

8lectromagnet

Control T#be

Slider


27/92

* Cha/ter . Seed Deli2er% S%stem

Fig#re .5B Rela% dri2er


28/92

.0. 8ngineering *0

From Deli2er% T#be

!ir Press#reRed#ction 1oles

8lectromagnet

$loc)er

8(ection Sensor Light $arriers

Seed 8(ection

Fig#re .6B Seed e(ection mechanism


29/92

*3 Cha/ter . Seed Deli2er% S%stem

Fig#re .7B 8(ection sensor schematic

28- >&tendabi#ity and $ossib#e %mprovements

28-81 .ore Seed Types

The seed deli2er% s%stem is e;tendable to more seed t%/es than in the c#rrent stage.

The latest selection mechanism alread% ofers the /ossibilit% to be ada/ted to seed t%/es of adiferent sie class. If for an% reason a desired seed t%/e does not com/l% with the slidermechanism b#t re+#ires another selection /rinci/le an additional handling mechanism can

be designed and added to the s%stem b% attaching it in series with the c#rrent design to thedeli2er% t#be. Therefore the commonalit% of the two mechanisms wo#ld be the deli2er%thro#gh air /ress#re.

28-82 Sensors on the S#iders

! f#rther im/ro2ement co#ld be the addition of sensors at the end of the electro-

magnets to determine whether the single sliders reach their end /ositions or not. This wo#ldma)e s#re that the seeds in the seedbo;es ha2e the highest /robabilit% to fall into the hole ofthe slider mechanism and get blown of to the o#tlet. Se2eral tests showed that if the slidersreached their end /ositions a seed gets /lanted with a 2er% high /robabilit%.


30/92

Chapter

*+,Tab#e !or Ti#ing

A )ariety of #ossible #lanting conce#ts has been discussed. he usageof a $ater soluble foil and s#ray glue is #ro#osed to create a tiled

gro$ingflo$er image. +urther the mechanical engineering of a static

#lanting mechanism that integrates the seed deli)ery system

de)elo#ed in the #re)ious cha#ter is #resented. he design of a

corres#onding electronical system and a control soft$are com#letes

this cha#ter.

81 Concept

! static robot is to be b#ilt which /lants fi2e diferent )inds of seeds onto a s#bstrate selectedbelow #sing the seed deli2er% s%stem /ro/osed in the /re2io#s cha/ter. The s#bstrate is

/laced #nderneath the mani/#lator of the E-Table. If the chosen s#b- strate re+#iresadditional adhesion a small amo#nt of dissol2ing and bio-degradable gl#e is a//lied to/re2ent the dis/lacement of the seeds. Finall% a thin la%er of soil or a second sheet ofs#bstrate is /laced on to/ of the seeds to allow trans/ortation and storage.

8181 Substrate

In table 0.* a set of diferent /ossible materials s#ch as P?!* organic nonwo2en

fabric /a/er or soil is disc#ssed. The trade-of between handling sim/licit% cost efecti2enessand ecological com/atibilit% leaded to the selection of the P?! foil a2ailable in small+#antities at *6. Its ma(or ad2antages are the eas% handling and the good water sol#bilit%.F#rther it is chea/er than the nonwo2en fabric and biologicall% more com/atible than the/a/er sol#tion. The limitation on the a//licable gl#e t%/es is insignificant as there e;ist2ario#s adhesi2es s#itable for P?!. Direct a//lication on soil was discarded d#e to its hea2%weight and the difc#lties for storage witho#t germinating seeds.

8182 G#ue

De/ending on the s#bstrate diferent gl#e t%/es wo#ld be /ossible. The most im-

/ortant criteria areB

K$io-degradabilit%

K1armlessness to the seeds*Pol%2in%lalcohol

Prod#ct nameB Sol2% from S#l)% G #termann. This /rod#ct is commonl% #sed as a stabilier for +#iltinga//lications.

*4


31/92

*5 Cha/ter 0. E-Table for Tiling

.ethodSoi#

$4A !oi#

owers aregrown

- =o materials thatco#ld harm the en2i-ronment

- 'ater sol#ble

- ?er% light and th#seas% to trans/ort andstore

- Possibilit% for /rintingendless sheets if the foilis /ro2ided on aroll

- =o remaining /arts inthe gro#nd

- 'ater sol#ble

'isadvantages

- =eeds a frame to holdthe soil together

- 1ea2%- Difc#lt for trans-

/ortation and storage

- Limited gl#e t%/es @no

water based gl#es a/-/licableA

- Costl% for small +#an-tities

n

on7oven!abric

@ organic eece

$aper

- ?er% light and th#s

eas% to trans/ort andstore

- Possibilit% for /rintingendless sheets if the foilis /ro2ided on aroll

- =o remaining /arts inthe gro#nd

- Stronger than the P?!foil

- 8as% to trans/ort and

store- Possibilit% for /rinting

endless sheets if the/a/er is /ro2ided on aroll

- Se2eral gl#e t%/es a/-/licable

Table 0.*B S#bstrates

- Limited gl#e t%/es @no

water based gl#es a/-/licableA

- Dissol2es slower thanthe P?! foil

- ?er% e;/ensi2e

- =eeds more time todissol2e

- Lea2es chemicals onthe gro#nd

- Seeds m#st be more ro-b#st to grow thro#ghthe sheets

- Possibl% not entirel%bio-degradable


32/92

0.. 8ngineering *6

K'ater sol#bilit%

KSim/le a//lication

KFi;ing the seed /osition

Some ideas areB 'ater sol#ble gl#e s/ra% corn-starch-water-mi; corn-starch-oli2e oil-mi;egg white hairs/ra% etc. !n im/ortant /oint is that the gl#e dissol2es in water s#ch that theseeds are not enclosed in a gl#e shell and the germination is s#//ressed therefore. !lso thereshall not remain to;ic de/osit that contaminates the soil. !s /ro/osed in *: corn-starchwo#ld be a good sol#tion.

D#ring e;/erimental /hases it t#rned o#t that the o/timal ratio between waterand starch is hard to find. Too m#ch water means easier a//lication b#t dissol2ing s#bstrateand red#ced adhesion. More starch leads to difc#lties d#ring a//lication. !lso the waterbased gl#e seems not to be o/timal for storing sheets since it dissol2es the P?! foil o2er time.

!n alternati2e co#ld be to re/lace the water b% oil since it does not attac) the s#bstrate b#thas a red#ced adhesi2eness witho#t additional ingredients. F#rther mo#ld formation hasbeen obser2ed that ma% harm or s#//ress the germination of the seeds.

Therefore the water sol#ble gl#e s/ra%0was selected since it meets all the demandsand is readil% a2ailable at *6. This gl#e is es/eciall% made for the a//lication with the P?!foil hence it o2ercomes the drawbac) of earl% dissol2ing of the s#bstrate and has the same/ro/erties as the s#bstrate itself. For f#rther im/ro2ements of the /lanting robot it wo#ld be/ossible to a//l% the gl#e a#tomaticall% b% the mani/#lator in order to increase the le2el ofa#tomation and sim/lif% the /lanting /rocess.

82 >ngineering

8281 .echanica# 'esign

!n o2er2iew of the /latform is gi2en in fig. 0.*. The static robot shall be able to

/lant seeds on a +#adratic area of *m. There are se2eral standard robot config- #rations toachie2e s#ch a tas)B SC!R! delta or Cartesian mani/#lators wo#ld all fit the re+#irements.For sim/licit% a Cartesian robot in an 1-config#ration was chosen. The 1-config#rationofers more stabilit% than other Cartesian set#/s and can be b#ilt of relati2el% chea/ standardelements.

Actuation

For the act#ated a;es linear tooth-belted rails of the t%/e IG


33/92

*7 Cha/ter 0. E-Table for Tiling

E-!;is connection

ting!r

ea

8(ection

-!;is

E-Motor

Plan nd E-!;is

Limit Switches @A

-Motor

*st E-!;is

Limit Switches @EA Seed Dis/ensers

Fig#re 0.*B E-Table @,2er2iewA

$neumatic System

The /ne#matic s%stem consists of a /ress#re red#ction de2ice two electromagne-

ticall% controllable 2al2es and a /ress#re distrib#tor. The 2al2es are o/erated at 3?DC andare controlled b% the !rd#ino Mega microcontroller. The /ress#re red#ction de2ice allowsthe reg#lation of the s%stem /ress#re in order to ada/t for diferent seed /ro/erties. ! t#be thatcan be attached to an% /ress#re so#rce with a standard air /ress#re connector is #sed as thein/#t to the /ne#matic s%stem. Th#s the s%stem can be re#sed on the mobile /latform with anair /ress#re cartridge. !ll com/onents are from Festo and were dismo#nted from an #n#sed/ro(ect.

Structure

The str#ct#re is based on Item al#mini#m /rofiles of the sie class 5. There are

two /arallel longer /rofiles that com/ose the base str#ct#re for the shorter /rofiles mo#nted

across. ,n the first two crossing /rofiles the E-a;es as well as the limit switches are attached#sing a s/eciall% designed mo#nting str#ct#re. The -a;is is connected to the sliding carriageof the E-a;es b% an intermediate /late on which also a second /air of limit switches ismo#nted. ,n the -!;is no s#//orting str#ct#re is #sed. $etween the a;es a wooden /late isinstalled as a s#rface for the /lacement of the s#bstrate. The remaining crossing /rofiles ser2eas a mo#nting str#ct#re for the seed dis/ensers and all other a#;iliaries. =o connections ha2ebeen considered critical so no calc#lations were cond#cted for the described design. !llmechanical /arts ha2e been designed in accordance with the ind#strial standards as defined in*.

8282 >#ectronic System

The electronic s%stem of the E-Table is ill#strated in 0.. The s%stem integrates

the motors the corres/onding controllers and its a#;iliaries li)e the limit switches as well asall c#stom made electronics as described in section .0. The s%stem has two DC /ower lin)sone at 4?DC and one at 3?DC coming from an e;ternal so#rce. !ll electronics #nlessre+#ired otherwise b% the f#nctionalit% are /laced in a row besides the /lanting area.


34/92

0.. 8ngineering *9

8mergenc% Sto/


35/92

: Cha/ter 0. E-Table for Tiling

.otors and Contro##er

The linear a;es are dri2en b% a Ma;on R80: 5:' DC motor each. To /ro2ide

the needed tor+#e and /recision the two motors were s#//lied with /lanetar% gear heads@0B* red#ctionA. This gi2es a ma;im#m tor+#e of 74m=m0 N *.944=m and a nominals/eed of 74::r/m/0 N 059.46r/m. Combined with the transmission ratio of the a;es of55mm/t#rn this %ields a nominal linear s/eed of :.3*m/s. F#rther the motors are e+#i//edwith MR encoders with *:3 co#nts /er t#rn. Since the motor controllers #se +#adco#nts@+cA this f#rther increase the resol#tion b% a factor of fo#r. Th#s leading to a /ositioningresol#tion as calc#lated in form#la 0.* which is - e2en combined with the /recision of thea;es themsel2es of:.04mm - significantl% higher than re+#ired as the /lants cannot bee;/ected to grow /erfectl% 2ertical. Therefore no linear /osition sensors are needed.

55mm t#rn

3

+

c

*

:

3

t

#

r

n

I

n

c

0red*

N 6.::5*:3mmInc

@0.*A

The motors are each controlled b% a Ma;on 8P,S 34 /osition controller andare e+#i//ed with se2eral safet% elementsB $oth a;es are limited in the mo2ement b% anind#cti2e limit switch at each end. For the limit switches ind#cti2e sensors of the t%/e'englor I1::$H3*?D were integrated into the s%stem. These sensors o/erate at 3?DCand ha2e a normall% closed beha2io#r. This ens#res that the mo2ement is also bloc)ed if a/ower fail#re occ#rs on the sensor circ#it. !s an additional safet% element an emergenc%sto/ b#tton was added which immediatel% s#//resses all mo2ements.

8 So!t7are

! gra/hical #ser interface @Gower distance or /ict#re and colo#r

selection. To control the electromagnets and the 2al2es as well as to read the e(ection sensordata a scri/t in the !rd#ino al/ha en2ironment an ID8 coming with the !rd#ino Mega45: microcontroller was written. The /rogramming lang#age of this ID8 is based on COO.

881 Graphica# ?ser %nter!ace

In fig#re 0.0 the gra/hical #ser interface @G


36/92

into three /arts. ,n the left hand side the most im/ortant b#ttons for controlling thea//lication and the seeding /rocess are a2ailable. In the main window on the to/ right/osition the selected /ict#re is dis/la%ed. $eneath an image of the act#al /lanting /ict#recan be /re2iewed s#ch that the settings li)e >ower distance and field sie might be ad(#stedbefore /lanting. !lso it is /ossible to add or delete single seeds of the final /ict#re b%clic)ing into the /ict#rebo; and selecting the desired colo#r from the colo#r bar at the

bottom.If the o/en b#tton is clic)ed an o/en file dialog a//ears. The software acce/ts all commonimage formats and dis/la%s them in the #//er /ict#rebo;. 'hile o/ening the file it is /arsedinto a /i;el-arra% according to the /redefined settings selected in the /anel on the left. Th#sthe o/en file dialog also acce/ts t;t-files with thefollowing content which is alread% in the format of the /i;el-arra%B

E-Position @mmA -Position @mmA !RG$-Colo#r-?al#e E-Position @mmA -Position @mmA !RG$-Colo#r-?al#e


37/92

0.0. Software *

Fig#re 0.0B Gra/hical #ser interface

F#rther the #ser interface can read dat-files that list one /lanting /oint /er line in the formX;Y;T whereXandYare the /osition in millimetres andTis the seedbo;inde; @*-4A. The file ma% also contain comment lines starting with a#. Thesecomments are dis/la%ed when loading the file and are intended to instr#ct the #serwhich seeds to fill into the bo;es.

882 Arduino .icrocontro##er

!s written abo2e the !rd#ino microcontroller can be easil% /rogrammed in the

SDH !rd#ino al/ha. !t start#/ of the !rd#ino the initialiation ro#tine starts and defineswhich /ins are #sed for o#t/#t or in/#t. The start#/ /roced#re also initialies the interr#/ts#sed to read the e(ection sensor data. Thereafter a /olling algorithm begins to monitor theserial interface for incoming instr#ctions.

88 $#anting $rocess

!s ill#strated in fig. 0.3 the /lanting /rocess consists of two /arallel tas)s. The

G


38/92

Cha/ter 0. E-Table for Tiling

the goal /osition the !rd#ino tas) selects the seed and o/ens the 2al2es to deli2er it to thee(ection /ort. ,nce the /osition has been reached the !rd#ino o/ens the e(ection and readsthe sensor data. If a seed has been detected the /lanting was s#ccessf#l and the Gower images with a reasonableresol#tion.

3:::r/m55 mm m

0

red*

K5:sec t#rn N :.*9* sec @0.A

m.5sec:.*9* sec N :.396m @0.0A

The o2erall /lanting time is com/osed of the time needed to establish the magnetic

field of the slider act#ators and the electromagnetic 2al2es. F#rther the rela% ma% not beswitched too soon after the /ower has been t#rned of b% the M,SF8T as the ind#cti2ec#rrents of the magnets need to be dissi/ated b% the >%bac) diode first in order not to damage

the electronics and to a2oid feedbac) co#/ling. ,ther dela%s come from the time to reliabl%shoot the seeds from the dis/enser to the e(ection b% the air /ress#re and from the e(ectionmechanism itself. The latter incl#des the o/ening of the e(ection /ort and the detection of theseeds b% the sensor s%stem. !ss#ming a tile of a h#ndred seeding /oints @*:cm s/acingA the/rocess to /lant a s+#are meter ta)es a//ro;imatel% se2en min#tes when no fail#re on thes%stem occ#rred. Related to a growing time of abo#t three months this /lanting time isinsignificant.


39/92

0.0. Software 0

Position and SeedT%/e In/#t

8P,S

PositionController

Motors

!rd#ino

,/en Slider

,/en ?al2e

Close ?al2e

Close Slider

,/en ?al2e

Close ?al2e

'ait #ntilPosition reached

!rd#ino

8lectromagnets@Seeddis/enserA

Control Press#re?al2e

Deli2er% Press#re?al2e

=r of trials=o

,/en Magnet

Close Magnet

Seed e(ection

detected

8(ection ,/ening8lectromagnet

8(ection Sensor

Fail#re S#ccess

Fig#re 0.3B Planting /rocess >owchart

o

es es


40/92

3 Cha/ter 0. E-Table for Tiling


41/92

Chapter -

Testing

his cha#ter #resents the results from a testing #hase that has beenconducted to )erify the #erformance of the -able. he focus lied on

the reliability, #recision and re#eatability of the system. All tests

sho$ed that the s#ecications are com#letely satised.

-81 Setup

The seed deli2er% s%stem has been tested with diferent >ower seed s/ecies. The /lacement/roced#re as defined in section 0.0.0 has been #sed on a reg#lar grid /attern consisting of 53/lacements @See fig. 3.*A. For each /lace the n#mber of e(ected seeds was co#nted and their

distance from the reference /oint was di2ided into the classes se/arated at {:.4cm *cm*.4cm cm .4cm}. D#ring the tests the /erformance of the e(ection sensor has also beene2al#ated.

-82 Bumber o! >9ected Seeds

Two s/ecies with diferent seed sies ha2e been /lanted b% the mani/#lator #sing threediferent diameters of the slider boreB mm @SA 0mm @MA and 3mm @LA. !s a first s/ecies 'iola $ittroc(ianawere tested with slider sie S and M while %hlo& drummondiiwere /lanted with sliders M and L. The n#mber of e(ected seeds ha2e been co#nted and

ill#strated in fig. 3.. For the ?iolas the mean 2al#e was *.50 seeds /er e(ection for the smallslider and 3.44 for slider sie M with a 2ariance of :.30 res/. *.44. This res#lt is as e;/ectedand shows that the slider sie has a ma(or im/act on the n#mber of e(ected seeds and its2ariance. The Phlo; e;/eriment res#lted in a mean 2al#e of *.60 for the M slider and 3.:4for the large slider with 2ariances of :.5* res/. .90 which 2erifies the concl#sions of the?iola e;/eriment. The re+#irements as defined in section *.* are f#lfilled b% these res#lts.

D#ring the e;/eriments with ?iolas and the small slider 0 e(ection fail#res @no

e(ection in two trialsA ha2e been obser2ed res/. 0 fail#res with /hlo; @Slider MA. In contrastno fail#res ha2e been obser2ed with the larger sliders. This comes from the statistical factthat the larger slider holes ha2e a higher /robabilit% of selecting at least one seed and istherefore an e;/ected res#lt. To im/ro2e the reliabilit% the bore diameter co#ld be ada/tedmore /recisel% to the seed sie or a third trial in the /lanting /roced#re co#ld be added.

4


42/92

5 Cha/ter 3. Testing

Fig#re 3.*B Test set#/

-8 Seeding $recision

In the /recision tests no gl#e has been #sed in order to re#se the seeds and re/eat thee;/eriments. From +#alitati2e obser2ations it is e;/ected that the /recision is increasedsignificantl% when #sing gl#e. In fig. 3.0 3.3 and 3.4 the /ositions of the e(ected seeds foreach s/ecies are shown. In the left gra/h the s/atial distrib#tion of the e(ected seeds and inthe right /lot a corres/onding histogram are /resented.It is e;/ected that the /recision does not 2ar% significantl% between s/ecies b#tsmall diferences were obser2ed. This ma% be d#e to the seed form and sie of the diferents/ecies. Since Im/atiens and Phlo; ha2e a similar seed form b#t diferent sies @See section*.*.A and show similar res#lts it can be concl#ded that the seed form has a higher im/acton the /recision than the seed sie. This is 2erified b% the com/arison between ?iolas andIm/atiens that ha2e a similar sie b#t diferent forms.In fig. 3.5 the res#lts from all e;/eriments were combined and dis/la%ed. !bo#t

56 of the seeds were e(ected in a circle with a radi#s of *cm and abo#t 74 within *.4cmwhich com/lies with the s/ecification @See section *.*A.

-8- >9ection Sensor $er!ormance

D#ring the e;/eriments the e(ection sensor /erformance has been monitored andthe res#lts ha2e been di2ided into the following classesB

KTr#e /ositi2e @t#AB 8(ection Q Detection

KTr#e negati2e @tnAB =o e(ection Q =o detection

KFalse /ositi2e @f #AB =o e(ection Q Detection


43/92

3.3. 8(ection Sensor Performance 6

Percentage Percentage

Percentage Percentage

Fig#re 3.B =#mber of e(ected seeds /er /osition for diferent s/ecies and slider sies

Phlox,

Slider

L

Phlox,

Slider

M

50

0

40

0

30

0

20

0

10

0

0

0

1

2

3

8

9

1

2

3

8

9

Num

bero

See

d!

4

5

"

#

Num

bero

See

d!

4

5

"

#

$iola

,Slider

M

$io

la,

Slider

S

50

0

40

0

30

0

20

0

10

0

0

0

1

2

3

8

9

1

2

3

8

9

Num

bero

See

d!

4

5

"

#

Num

bero

See

d!

4

5

"

#


44/92

7 Cha/ter 3. Testing

3

2

1

0

1

2

3

%i!tribution50

45

40

35

30

25

20

15

10

5

0

&i!togram

3 2 1 0 1 2 3 1 2 3 4 5 "cm 'la!!

Fig#re 3.0B Position of e(ected ?iola seeds

3

2

1

0

1

2

3

%i!tribution50

45

40

35

30

25

20

15

10

5

0

&i!togram

3 2 1 0 1 2 3 1 2 3 4 5 "cm 'la!!

Fig#re 3.3B Position of e(ected Phlo; seeds

3

2

1

0

1

2

3

%i!tribution50

45

40

35

30

25

20

15

10

5

0

&i!togram

3 2 1 0 1 2 3 1 2 3 4 5 "cm 'la!!

Fig#re 3.4B Position of e(ected Im/atiens seeds3.3. 8(ectionSensorPerformance

%i!tribution

3

2

1

0

1

2

3

Num

bero

See

d!

()*

m

Num

bero

See

d!

()*

m

Num

bero

See

d!

()*

cm

Num

bero

See

d!

()*

m


45/92

50

45

40

35

30

25

20

15

10

5

0

&i!togram

9

3 2 1 0 1 2 3 1 2 3 4 5 "cm 'la!!

Fig#re 3.5B Position of e(ected seeds from all meas#rements

S/ecies Slider t# tn f# fn # r a

?iola S 45 *9 * *0 :.97 :.7* :.73

?iola M 53 : * * :.97 :.99Phlo; M 53 3 : * * :.97 :.99Phlo; L 53 : : : * * *

Im/atiens S 50 : * * :.64 :.65

Table 3.*B 8(ection sensor /erformance.t#B Tr#e /ositi2e.tnB Tr#e negati2e.f #B False/ositi2e.f nB False negati2e.#B Precision.rB Recall.aB !cc#rac%.@Definitions see te;tA

KFalse negati2e @f nAB 8(ection Q =o detectionFrom these 2al#es a /erformance anal%sis has been cond#cted. For each e;/eriment

the /recision has been calc#lated #sing#Nt#/@t#Of #A and the recall #singrN t#/@t#Of nA. Precision and recall 2al#es are /lotted in the fig. 3.6. F#rther the acc#rac% defined asaN @t#OtnA/@t#OtnOf #Of nA has been com/#ted for each e;/eriment. !s e;/ected

larger seeds and a higher amo#nt of seeds lead to a better /erformance of the sensor. This is/ro2ed b% the high acc#rac% /recision and recall 2al#es as listed in tab. 3.* in e;/erimentswith a high n#mber of seeds or b% a large sied s/ecies. The efect of the n#mber of seeds canes/eciall% be obser2ed in the two ?iola e;/eriments where the acc#rac% difers b% *4 forthe lower n#mber of seeds. 'ith Phlo; the n#mber of selected seed is not im/ortant sincethe sie of Phlo; seeds is large eno#gh to be reliabl% detected e2en for indi2id#al ones. In theIm/atiens e;/eriment the /erformance is worst as the Im/atiens ha2e the smallest seeds andalso are e(ected in low n#mbers.


46/92

0: Cha/ter 3. Testing

1+05

1

0+95

0+9

0+85

0+8

0+#5

0+#

Preci!ion-ecall o the ./ection Sen!or

$iola, Small Slider

$iola, Medium Slider

Phlox, Medium Slider

Phlox, Large Slider

matien!, Small Slider

0+# 0+#5 0+8 0+85 0+9 0+95 1 1+05Preci!ion

Fig#re 3.6B Precision and recall for the e(ection sensor for 2iolas with two diferent sliders.Larger n#mbers of seeds or larger sied seeds lead to a better sensor /erformance.

-eca

ll


47/92

Chapter

.obi#e $#at!orm

*ased on the static solution a conce#t for an autonomous mobile robot$as de)elo #ed. +irst, the #rereuisites and the underlying

assum#tions are discussed. %ossible locomotion and locali!ation

solutions $ere analy!ed follo$ed by a concrete #ro#o sition that

$ould be able to accom#lish the tas( of autonomously #lanting flo$er

images. his includes a si!e estimation, the integration of a

mani#ulator and a sensory system for controlling the robot.

81 Reuirements

This section defines the re+#irements and constraints on the mobile /latform of the gardeningrobot.

8181 Terrain "orm Constraints

!s ill#strated in fig. 4.* the terrain for the mobile /latform is a//ro;imatel% rect-

ang#lar and /lanar b#t not necessaril% horiontal. It is characteried b% the length

Aand width* b% the a2erage stee/ness the ma;im#m stee/nessma& thecon2e;it%3and the ro#ghnessD. The s/ecified limiting 2al#es are listed below.

KSieA, *B #s#all% aro#nd *:meach ma;im#m :m

KCon2e;it%3B !s small as /ossible ma;imal:.4mor :.:4min{A, *}

KRo#ghnessDB !s small as /ossible ma;imal:.4mor :.:4min{A, *}KStee/nessma&B ma;im#m:.04rad

8182 bstac#e Avoidance

The field is ass#med to be obstacle free b#t the robot sho#ld choose its /ath s#ch

that it red#ces the /robabilit% of dis/lacing or destro%ing an alread% /laced seed b% notdri2ing into /re2io#sl% /lanted areas. This does not re+#ire obstacle detection sensors b#trather the /ossibilit% that the robot can mar) seeds as /laced on the list of /ositions.=e2ertheless de/ending on the selected sensor s%stem @e.g. L!D!RA an obstacle a2oidancealgorithm can be im/lemented to allow /lanting growing >ower images on fields thatcontain trees roc)s or obstacles of other )inds. For safet% reasons b#m/er switches can beadded to the robot.

0*


48/92

0 Cha/ter 4. Mobile Platform

@A, *A

@:, *A @A,:A

@:,:A

aA Terrain sieA, *

ma&

bA Terrain stee/nessma&and con2e;it%3

cA Terrain ro#ghnessD

Fig#re 4.*B Terrain constraints

3

D


49/92

4.. Locomotion Conce/t 00

818 $recision

The robot needs - as the E-Table - a seeding /recision of a few centimetres to create

reasonable >ower images. !s the seeding mani/#lator sho#ld be able to correct an ofsetbetween the robotJs act#al and desired /ose to ens#re the seeding /recision the localiationacc#rac% is re+#ired to be higher or at least as good as the demanded seeding /recision. Thisim/lies a localiation /recision of a few millimetres #/ to ma;imall% two centimetres for thes/atial /ositioning and an orientation error lower than :.:4 radians. $etter localiation isdesired as small heading errors lead to a large mani/#lator ofset b#t to achie2e this/recision more e;/ensi2e sensors are re+#ired.

818- Seeding Constraints

The robot can o/erate either in a single- or a m#lti/ass beha2io#r. In the latter

case the robot /asses the field m#lti/le times with a diferent set of seeds each time whereas

in the former /roced#re the robot /asses the field onl% once with the entire set of seeds. Them#lti/ass o/eration mode is es/eciall% #sed when seeds of s/ecies with significantl% diferentgermination and growing d#rations ha2e to be /lanted or when the n#mber of diferent seedse;ceeds the n#mber of seedbo;es that can be carried on the robot. The single /ass mode is#sef#l e.g. when diferent colo#red seeds of the same s/ecies ha2e to be /lanted.

82 ocomotion Concept

There are miscellaneo#s locomotion conce/ts that are commonl% #sed in robotics. These/ossibilities ha2e been e2al#ated for the s#itabilit% to an o#tdoor /lanting a//lication. Themane#2erabilit% in the s/ecified terrain the stabilit% and the low im/acts on the en2ironmentare #sed as criteria.

8281 >va#uation


50/92


egged ocomotion

Com/ared to wheels or trac)s legged locomotion needs a com/le; low-le2el control str#ct#re

and might be #nable to mo2e stable on lose gro#nd in stee/ terrain d#e to the lower s#rfacecontact area. In m#lti/ass o/eration legged locomotion wo#ld be ad2antageo#s since thelegs co#ld be /laced /recisel% between two /lants. This wo#ld re+#ire an acc#rate sensors%stem to detect the /lants.

Cab#e Suspended System

!s seen in s/orts e2ents a camera s%stem @See *7A is mo#nted on se2eral cables and can bemane#2ered o2er a /la%ing arena in three dimensions. This /rinci/le co#ld be ada/ted for the/lanting of growing >ower images b% e;changing the camera with a seed deli2er% s%stem.The main ad2antages wo#ld be the /lanting /recision the /ossibilit% to add /lants at an%growing state of the alread% /laced seeds witho#t harming them and the red#ndanc% of an

e;ternal localiation s%stem. The ma(or drawbac) is the cost and efort to set#/ the s%stemas it needs fi;ed /oles at the corners of the field for the cable s%stem.

Airborne

!n airborne seed deli2er% s%stem e.g. with a coa;ial helico/ter or a +#adrotor is notconsidered as a//licable for the gardening robot. The ad2antage that it co#ld mane#2erinde/endent of the terrain where the seed are deli2ered is almost negligible as the terrain isconsidered to be more or less >at and witho#t ste/s. In a m#lti/ass o/eration an airbornes%stem wo#ld not damage alread% germinated and growing /lants. The disad2antage i.e. thefact that the seeds can be blown awa% b% the rotor downwash is +#ite serio#s. If thehelico/ter is >%ing at low altit#des to deli2er the seed this a//lies to alread% /laced seedsnearb% the c#rrent /osition and if the helico/ter is >%ing at higher altit#de in order to/re2ent alread% /laced seeds to be dislocated the c#rrent seed is li)el% to be /lantedinacc#ratel%.

8282 Se#ection

The wheeled locomotion conce/t is considered as most a//licable for the #se as s/ecified.The sim/licit% the range of /ossible config#rations and the stabilit% are the main reasons forthis selection. !lso the wide #sage of wheeled locomotion and therefore the large amo#nt of/#blic domain information was another decision /oint. 1ence all other sol#tions arediscarded and the wheeled conce/t is f#rther de2elo/ed b% /ro/osing the wheel config#ration

in the section below.

828


51/92

4.0. Localiation 04

8 oca#i;ation

For the localiation and /ose estimation of the robot there are se2eral /ossibilities which are

all considered as standard sol#tions for robot localiation. The a//lica- bilit% of thesesol#tions for the localiation of the gardening robot is e2al#ated in this section. The criteriaare the com/le;it% of the wor)ing /rinci/le the re+#ired hardware e+#i/ment on the robotthe hardware e+#i/ment that is to be set #/ for each de/lo%ment and the re+#ired algorithms.The sol#tions below are intended to be #sed in combination with odometr% as gi2en b% thedri2ing motor or wheel encoders.

881 >va#uation

ec-

ti2e material @mirrorsA. The re>ected beam can be detected b% a sensor ne;t to the laser

so#rce and the rotation of the mod#le is meas#red b% an encoder. If a beam is detected therelati2e angle of the beacon to the robot is stored. If eno#gh angles are collected the robot/ose can be calc#lated b% sim/le triang#lation. The s%stem re+#ires that the /h%sical locationof the beacons and the ma/ stored in the robot are highl% correlated in order to minimie theerror. This can be achie2ed either b% /recise /lacement of the beacons andor that the/ositions of the beacons are meas#red acc#ratel% after /lacement b% an o/erator e.g. #singgeodetical metrolog% instr#ments. This increases the set-#/ time dramaticall%. !n alternati2ewo#ld be a SL!M*a//roach which a#tomaticall% b#ilds and #/dates a ma/.

*Sim#ltaneo#s Localiation and Ma//ing


52/92


!ss#ming that the rotating laser s%stem is e+#i//ed with a *5bit ang#lar encoder ameas#rement error of one encoder tic) corres/onds to a localiation error of almost onemillimetre in a 2iewing distance of *:m when ass#ming sin@&A N&for small&.

rad N rad*

5

54405 N 94.763*:5rad @4.*A

94.763*: 5rad*::::mm N :.947mm @4.A

n,3oard 4ision System

Similar to the rotating laser sol#tion an omnidirectional camera or a m#lti/le camera

s%stem which co2ers the f#ll 05: degrees field of 2iew or a rotating camera is mo#nted on

the robot. In the corners of the field beacons with easil% detectable tags s#ch as !RTags are /laced. 'ith standard com/#ter 2ision algorithms the relati2e /osition of the tags tothe robot can be calc#lated and then the same calc#lations as in the rotating laser sol#tionare cond#cted to find the robot /ose. The /roblem is that the resol#tion of the camera has tobe reasonabl% high to detect the tags o2er the entire field.!ss#ming a set#/ of three f#ll 1D cameras with a *: degrees field of 2iew each is #sed there+#ired tag sie is abo#t 0:cm. This 2iewing angle /er /i;el is calc#latedas

/0 rad N *.:9**:0rad @4.0A*9:/; /;

,n a distance of *:m the width$corres/onding to */; is deri2ed @ass#ming

sin@&A N&for small&A

$N *.:9**:0rad*::::mm N *:.9*mm @4.3A

'ith a mar)er sie of 0:cm this corres/onds to 6/; which is s#fcientl% high

for a good detection rate according to Fiala . The /i;el width defines also the /ositioning/recision.

>&terna# Camera

! camera is mo#nted on a /ole ne;t to the field. This camera trac)s the robot /ose

#sing a mar)er on the to/ of the robot which allows fast detection and localiation. There+#ired resol#tion of the camera is +#ite high in order to ens#re a correct localiation. !nalternati2e to a high resol#tion camera wo#ld be a /an-tilt-oom- camera b#t which wo#ld

then need again a /recise orientation sensor to determine the 2iewing direction of the camera.

thernet oca#i;ation

'iFi localiation has been st#died b% 1oward et al.4 #sing the signal strength as

an indicator. For this /#r/ose a signal strength /ro/agation model and a signal strengthma/ are #sed. The /recision is stated to be aro#nd *:cm in the tested indoor en2ironment. Itis e;/ected that the /recision co#ld be increased in an obstacle free o#tdoor en2ironmentb#t it is not e;/ected to reach the re+#irements witho#t 2er% f#ndamental research on 'iFilocaliation and an a//ro/riate signal strength /ro/agation model. The s%stem calibration b%the /reliminar% creation of a signal strength ma/ is considered inefcient as the s%stem isintended to be de/lo%ed onl% once a %ear in the same /lace. This wo#ld im/l% that the signalstrength is meas#red b% /recisel% localied meas#rement tools for each field which wo#ld

/robabl% need more efort than the act#al seeding /rocess.


53/92

4.3. Re+#ired Com/onents and Sie 8stimation 06

?#trasonic Triangu#ation

In #ltrasonic triang#lation time-of->ight meas#rements of #ltrasonic wa2es are #sed to

determine the distance between a beacon and an ob(ect to be localied. ec- tions from an%s#rro#nding ob(ect also the gro#nd. This is the main reason wh%#ltrasonic localiation is not considered 2er% s#itable for gro#nd a//lications.

882 Se#ection

The sol#tions e2al#ated in the section abo2e are s#mmaried in tab. 4.*. 'hich sol#tion ismost a//licable is mainl% defined b% the terrain. If the terrain has low con2e;it% and israther smooth @low ro#ghnessA the rotating laser as well as an onboard 2ision s%stem ismost s#itable. The stee/ness of the terrain does not in>#ence this selection as both /ro/osed

onboard s%stems re+#ire a more or less /lanar b#t not necessaril% horiontal terrain. If theterrain does not fit these restrictions the onboard s%stem has to be /laced on a balancing/latform. !n alternati2e for a non-/lanar terrain wo#ld be an e;ternal s%stem e.g. ane;ternal 2ision s%stem or a laser trac)er. For f#rther im/ro2ements of /ose estimation acom/ass can be added to the s%stem which significantl% enhances the orientation acc#rac%.

8- Reuired Components and Si;e >stimation

8-81 vervie7

It is ass#med that the mobile /latform consists of the com/onents listed in table 4.. The robot

wo#ld be based on a diferential dri2e /latform with a#;iliar% /assi2e castor wheels for/re2enting lateral and longit#dal fall-o2er and g#aranteed stabilit% in ro#gher terrain. ,ne/assi2e wheel wo#ld be mo#nted centred in front of the two acti2e wheels and one castorwheel wo#ld be attached to each end of the mani/#lator a;is as showed in fig. 4.. It has tobe noted that the gro#nd clearance is high eno#gh to not damage growing /lants inm#lti/ass o/erations. Therefore a wheel diameter of abo#t :cm is /ro/osed to allowcontact-free mo2ements of the robot o2er germinating seeds. F#rther soft s/i)ed tractort%res wo#ld be /referred to create eno#gh traction on lose gro#nd. The width and softness/ro/ert% of those t%res lead to a large contact area of the wheels which is im/ortant foro#tdoor locomotion.

In reg#lar /lanting grids the distance between single /lants is t%/icall% set to *:cms#ch that the distance between the acti2e wheels has to be set to a//ro;imatel% 3:cm.

Therefore the robot can mo2e between grown >owers witho#t destro%ing them. TheL!D!R s%stem sho#ld be installed as high as /ossible in order to detect the re>ecti2ebeacons at an% sit#ation es/eciall% in en2ironments with a high ro#ghness. ,/tionall% itco#ld be mo#nted on a balancing /latform to com/ensate for con2e;it% and ro#ghness.

For high le2el control li)e /ath /lanning obstacle a2oidance and the /lanting algo-rithm an onboard la/to/ wo#ld be /referred. This ofers the /ossibilit% to sim/lif% theinteraction between o/erator and robot b% #sing a gra/hical #ser interface. F#r- ther a remotecontrol o2er 'iFi or $l#etooth co#ld be #sef#l for sending commands to the wor)ing robot. Ifa la/to/ is installed on the /latform the re+#ired hardware wo#ld alread% be a2ailable.


54/92


Table 4.*B Localiation methods s#mmar%

.ethod

dG$S

Trac1er

aser

aser

Rotating

4ision

0n,3oard

sion>

&tern

a#4i,

gu#ation

ower images the idea of /lant-

ing grass seeds emerged. De/ending on the s/ecies of >owers the minim#m seed distancebetween two /lants is defined from *:cm to :cm while grass does not ha2e s#chrestrictions. $#t the seeding /rocess of grass is diferent com/ared to the /lanting mechanismof >owers where onl% a small amo#nt of seeds are dro//ed onto the gro#nd. For dense grassimages one has to /rint /atches of grass seeds containing h#ndreds of single seeds. Th#s thec#rrent dis/enser mechanism is not s#itable for this a//lication and has to be redesigned. !reasonable sol#tion wo#ld be a modification of the 2ac##m /ic)-#/ s%stem as described in.*.*. Instead of ha2ing a /redefined n#mber of holes at the ti/ of the 2ac##m t#be a thin

mem- brane and a 2ariable a/ert#re co#ld be mo#nted. This wo#ld allow to ada/t the radi#sof the efecti2e 2ac##m ti/ and therefore to change the amo#nt of deli2ered seeds. The bigad2antage is that this mechanism is a//licable to an% )ind of seed form and sie hence alsofor >owers. It additionall% lowers the re+#ired time for /lanting grass images since a largen#mber of seeds co#ld be /lanted sim#ltaneo#sl%. The drawbac) of the 2ac##m deli2er%s%stem @the need for a third a;isA and legal concerns gi2en b% the /atent of Heller et al. 5remain.=e2ertheless a set of grass s/ecies has been tested and the following s#bset ma%wor) with the c#rrent robotic /lanterB

K5elica nutansB 'or) almost /erfectl%

K5olinia gaeruleaB 'or) well

KAntho&andum odoratumB 'or)K5elica ciliataB 'or)

KAgrosstis ru#estrisB 'or) b#t too small for reliable e(ection detection

The following s/ecies do not wor) or need mechanical ad(#stments to the robot d#e to sieseed form or slider (amming.

K3ynosurus cristatusB Too small @Slider ammingA

K%oa al#inaB ,ddl% sha/ed form

KAlo#ecurus #ratensisB ,ddl% sha/ed form

K*ri!a mediaB Too big might wor) with a bigger slider hole


63/92

Appendi& A

'atasheets

36


64/92

-. 30

30 mm, rahitbr!ten, "0 att

LagerrogrammStandardrogrammSonderrogramm au 6nrage7

e!tellnummern

M 1:2

gem!! Ma!!bild 310005 31000" 310007 310008 310009ellenlnge 15+# ge:r;t au 8+# mm 2"8193 2"8213 2"8214 2"8215 2"821"

MotordatenWerte bei Nennspannung

1 Nenn!annung $ 12+0 18+0 24+0 3"+0 48+0 2Leerlaudreh;ahl minon 25E' =ird bei dauernderela!tung die maximal ;ul!!ige -otortemeraturerreicht F thermi!che ren;e+

Kur%%eitbetrieb%er Motor dar :ur;;eitig und =ieder:ehrend berorbehalten


66/92

Planetengetriebe P 32 632 mm, 0+#5 < 4+5 Nm@echni!che %aten

Planetengetr iebe6btrieb!=elle

ellendurchme!!er al! Jtion6btrieb!=ellenlagerung- a d i a l ! i e l , 5 mm a b Gl a n ! c h

6xial!iel

gerade>er;ahntro!treier Stahl

8 mm?ugellager

max+ 0+14 mmm a x + 0 + 4 mm

M a x + ; u l + - a d i a l l a ! t , 1 0 mm a b Gl a n ! chMax+ ;ul!!ige 6xialla!t

Max+ ;ul!!ige 6ure!!:rat % re h ! i n n , 6 n t r i e b ;u 6 b t r i e b.mohlene Motordreh;ahl.mohlener @emeraturbereich

140 N120 N120 N

F "000 min< 1


67/92

232 ma,*n gear 6u!gabe 6ril 2010 Knderungen >orbehalten


68/92

MODELLMK1T

E

C

H

N

I

S

CH

E

I

N

F

O

R

M

A

T

I

O

N

E

Eigenschaften: U

U

spielfrei und verdrehsteif

Ausgleich von Fluchtungsfehlern

ISO 4029U durch integrierte Demontgenut

!nn ein A"flchen der #elle entfllen

U preis$erte Ausf%hrung

U niedriges &r'gheitsmoment

Material: (lg us hochelstischem Edelsthl) *"e AL

(lg+ Serie 0), &om"!

Aufbau: *"en mit rdilen -lemmschru"en

(isherige

L.sungen+

Bestellbeisiel

M-/ , 21 4 ,

Te!eratur"

bereich:

#reh$ahlen:

%ebens&auer:

DI* 9/1 und integrierter Demontgenut

30 "is 5/206 7

(is 208000 /min8 %"er 208000 /min8

in usge$uchteter Ausf%hrung

(ei (echtung der techn8 in$eise sind die

-upplungen duerfest und $rtungsfrei


69/92

Modell

Serie

:esmtl'nge

mm (ohrungs ; D/

24

/,/),

/9

Stndrd"ohrung < mmB D/2 2 1 1 1/0 1/0 /0 /0

-lemmschru"en ISO 4029 /CM2 /CM2), /CM /CM 2CM 2CM4 2CM, 2CM1

EAn=ugsmoment *mB 0), 0)(N*

a!ic 02 0,38 0,08 1+000 54 &@% 3M Neoren mit G 9

#5

Standard 02 0,43 0,08 1+000 54 M@%3 PA mit Stahl 9

100

m a x + - a d i a l b e l a ! tu n g A m le n : l ag e r max+ e!ch=indig:eit max+

Po!ition!

Documents

Gardening Robot