基于RaspberryPI的履帶式機械臂智能小車外文翻譯

外文翻譯

An

adaptive

dynamic

controller

for

autonomous

mobile

robot

rajectory

trackingabstract

This

paper

proposes

an

adaptive

controller

to

guide

an

unicycle-like

mobile

robotduring

trajectory

tracking.

Initially,

the

desired

values

of

the

linear

and

angularvelocities

are

generated,

considering

only

the

kinematic

model

of

the

robot.

Next,such

values

are

processed

to

compensate

for

the

robot

dynamics,

thus

generating

thecommands

of

linear

and

angular

velocities

delivered

to

the

robot

actuators.

Theparameters

characterizing

the

robot

dynamics

are

updated

on-line,

thus

providingsmaller

errors

and

better

performance

in

applications

in

which

these

parameters

canvary,

such

as

load

transportation.

The

stability

of

the

whole

system

is

analyzed

usingLyapunov

theory,

and

the

control

errors

are

proved

to

be

ultimately

bounded.Simulation

and

experimental

results

are

also

presented,

which

demonstrate

the

goodperformance

of

the

proposed

controller

for

trajectory

tracking

under

different

loadconditions.

1.

Introduction

Among

different

mobile

robot

structures,

unicycle-like

platforms

are

frequentlyadopted

to

accomplish

different

tasks,

due

to

their

good

mobility

and

simpleconfiguration.

Nonlinear

control

for

this

type

of

robot

has

been

studied

for

severalyears

and

such

robot

structure

has

been

used

in

various

applications,such

as

surveillance

and

floor

cleaning.

Other

applications,

like

industrial

load

transportationusing

automated

guided

vehicles

(AGVs)

automatic

highway

maintenance

andconstruction,

and

autonomous

wheelchairs,

also

make

use

of

the

unicycle-like

structure.

Some

authors

have

addressed

the

problem

of

trajectory

tracking,

a

quiteimportant

functionality

that

allows

a

mobile

robot

to

describe

a

desired

trajectorywhen

accomplishing

a

task.

An

important

issue

in

the

nonlinear

control

of

AGVs

is

that

most

controllersdesigned

so

far

are

based

only

on

the

kinematics

of

the

mobile

robot.

However,

when

high-speed

movements

and/or

heavy

load

transportation

arerequired,

it

becomes

essential

to

consider

the

robot

dynamics,

in

addition

to

itskinematics.

Thus,

some

controllers

that

compensate

for

the

robot

dynamics

have

beenproposed.

As

an

example,

Fierro

and

Lewis

(1995)

proposed

a

combined

kinematic/torquecontrol

law

for

nonholonomic

mobile

robots

taking

into

account

the

modeled

vehicledynamics.

The

control

commands

they

used

were

torques,

which

are

hard

to

deal

with

when

regarding

most

commercial

robots.

Moreover,

only

simulation

results

werereported.

Fierro

and

Lewis

(1997)

also

proposed

a

robust-adaptive

controller

based

onneural

networks

to

deal

with

disturbances

and

non-modeled

dynamics,

althoughnot

reporting

experimental

results.

Das

and

Kar

(2006)

showed

an

adaptive

fuzzylogic-based

controller

in

which

the

uncertainty

is

estimated

by

a

fuzzy

logic

systemand

its

parameters

were

tuned

on-line.

The

dynamic

model

included

the

actuatordynamics,

and

the

commands

generated

by

the

controller

were

voltages

for

the

robotmotors.

The

Neural

Networks

were

used

for

identification

and

control,

and

the

controlsignals

were

linear

and

angular

velocities,

but

the

realtime

implementation

of

their

solution

required

a

high

-performance

computer

architecture

based

on

a

multiprocessorsystem.

Ontheotherhand,DeLaCruzandCarelli(2006)proposedadynamicmodelusinglinearandvelocitiesasinputs,andshowedthedesignofatrajectorytrackingcontrollerbasedontheirmodel.Oneadvantageoftheircontrolleristhatitsparametersaredirectlyrelatedtotherobotparameters.However,iftheparametersarenotcorrectlyidentifiedoriftheychangewithtime,forexample,duetoloadvariation,theperformanceoftheircontrollerwillbeseverelyaffected.Toreduceperformancedegradation,on-lineparameteradaptationbecomesquiteimportantinapplicationsinwhichtherobotdynamicparametersmayvary,suchasloadtransportation.Itisalsousefulwhentheknowledgeofthedynamicparametersislimitedordoesnotexistatall.Inthispaper,anadaptivetrajectory-trackingcontrollerbasedontherobotdynamicsisproposed,anditsstabilitypropertyisprovedusingtheLyapunovtheory.Thedesignofthecontrollerwasdividedintwoparts,eachpartbeingacontrolleritself.Thefirstoneisakinematiccontroller,whichisbasedontherobotkinematics,andthesecondoneisadynamiccontroller,whichisbasedontherobotdynamics.Thedynamiccontrolleriscapableofupdatingtheestimatedparameters,whicharedirectlyrelatedtophysicalparametersoftherobot.Bothcontrollersworkingtogetherformacompletetrajectory-trackingcontrollerforthemobilerobot.Thecontrollershavebeendesignedbasedonthemodelofaunicycle-likemobilerobotproposedbyDeLaCruzandCarelliAs-modificationtermisappliedtotheparameter-updatinglawtopreventpossibleparameterdrift.Theasymptoticstabilityofboththekinematicandthedynamiccontrollersisproven.Simulationresultsshowthatparameterdriftdoesnotariseevenwhenthesystemworksforalongperiodoftime.Experimentalresultsregardingsuchacontrollerarealsopresentedandshowthattheproposedcontrolleriscapableofupdatingitsparametersinordertoreducethetrackingerror.Anexperimentdealingwiththecaseofloadtransportationisalsopresented,andtheresultsshowthattheproposedcontrolleriscapableofguidingtherobottofollowadesiredtrajectorywithaquitesmallerrorevenwhenitsdynamicparameterschange.Themaincontributionsofthepaperare:(I)theuseofadynamicmodelwhoseinputcommandsarevelocities,whichisusualincommercialmobileobots,whilemostoftheworksintheliteraturedealswithtorquecommands;(2)thedesignofanadaptivecontrollerwithas-modificationterm,whichmakesitrobust,withthecorrespondingstabilitystudyforthewholeadaptivecontrolsystem;and(3)thepresentationofexperimentalresultsshowingthegoodperformanceofthecontrollerinatypicalindustrialapplication,namelyloadtransportation.2.DynamicmodelInthissection,thedynamicmodeloftheunicycle-likemobilerobotproposedbyDeLaCruzandCarelli(2006)isreviewed.Fig.1depictsthemobilerobot,itsparametersandvariablesofinterest.uandoarethelinearandangularvelocitiesdevelopedbytherobot,respectively,Gisthecenterofmassoftherobot,Cisthepositionofthecastorwheel,Eisthelocationofatoolonboardtherobot,histhepointofinterestwithcoordinatesxandyintheXYplane,cistherobotorientation,andaisthedistancebetweenthepointofinterestandthecentralpointofthevirtualaxislinkingthetractionwheels(pointB).Thecompletemathematicalmodeliswrittenas.whеrеиgаndоаrеthеdе??rеdvаluе?оfthеl?nеаrаndаngulаrvеlос?t?е?,respectively,andrepresenttheinputsignalsofthesystem.Avectorofidentifiedparametersandavectorofparametricuncertaintiesareassociatedwiththeabovemodelofthemobilerobot,whichare,respectively.wheredxanddyarefunctionsoftheslipvelocitiesandtherobotorientation,duanddoarefunctionsofphysicalparametersasmass,inertia,wheelandtirediameters,parametersofthemotorsanditsservos,forcesonthewheels,etc.,andareconsideredasdisturbances.Theequationsdescribingtheparametershwerefirstlypresentedin,andarereproducedhereforconvenience.TheyareItisimportanttopointoutthatanonholonomicmobilerobotmustbeorientedaccordingtothetangentofthetrajectorypathtotrackatrajectorywithsmallerror.Otherwise,thecontrolerrorswouldincrease.Thisistruebecausethenonholonomicplatformrestrictsthedirectionofthelinearvelocitydevelopedbytherobot.So,iftherobotorientationisnottangenttothetrajectory,thedistancetothedesiredpositionateachinstantwillincrease.Thefactthatthecontrolerrorsconvergetoaboundedvalueshowsthatrobotorientationdoesnotneedtobeexplicitlycontrolled,andwillbetangenttothetrajectorypathwhilethecontrolerrorsremainsmall.3.ExperimentalresultsToshowtheperformanceoftheproposedcontrollerseveralexperimentsandsimulationswereexecuted.Someoftheresultsarepresentedinthissection.The.proposedcontrollerwasimplementedonaPioneer3-DXmobilerobot,whichadmitslinearandangularvelocitiesasinputreferencesignals,andforwhichthedistancebinFig.2isnonzero.Inthefirstexperiment,thecontrollerwasinitializedwiththedynamicparametersofaPioneer2-DXmobilerobot,weighingabout10kg(whichwereobtainedviaidentification).BothrobotsareshowninFig.3,wherethePioneer3-DXhasalasersensorweighingabout6kgmountedonitsplatform,whichmakesitsdynamicssignificantlydifferentfromthatofthePioneer2-DX.Intheexperiment,therobotstartsatx=0.2mandy=0.0m,andshouldfollowaeirculartrajectoryofreference.Thecenterofthereferencecircleisatx=0.0mandy=0.8m.Thereferencetrajectorystartsatx=0.8mandy=0.8mandfollowsacirclehavingaradiusof0.8m.After50s,thereferencetrajectorysuddenlychangestoacircleofradius0.7m.Afterthat,theradiusofthereferencetrajectoryalternatesbetween0.7and0.8meach60s.presentsthereferenceandtheactualrobottrajectoriesforapartoftheexperimentthatincludesachangeinthetrajectoryradius,Inthiscase,theparameterupdatingwasactive.showsthedistanceerrorsforexperimentsusingtheproposedcontroller,withandwithoutparameterupdating,tofollowthedescribedreferencetrajectory.Thedistanceerrorisdefinedastheinstantaneousdistancebetweenthereferenceandtherobotposition.Noticethehighinitialerror,whichisduetothefactthatthereferencetrajectorystartsatapointthatisfarfromtheinitialrobotposition.First,theproposedcontrollerwastestedwithnoparameterupdating.ItcanbeseeninFig.5that,inthis.case,thetrajectorytrackingerrorexhibitsasteady-statevalueofabout0.17m,whichdoesnotvaryevenafterthechangeintheradiusofthereferencetrajectory.Thisfigurealsopresentsthedistanceerrorforthecaseinwhichthedynamicparametersareupdated.Byactivatingtheparameter-updating,andrepeatingthesameexperiment,thetrajectorytrackingerrorachievesamuchsmallervalue,incomparisonwiththecaseinwhichisnoig.3.therobptsuesdintheexperiments.ConcusionAnadaptivetrajectory-trackingcontrollerforaunicycle-likemobilerobotwasdesignedandfullytestedinthiswork.Suchacontrollerisdividedintwoparts,whicharebasedonthekinematicanddynamicmodelsoftherobot.Themodelonsideredtakesthelinearandangularvelocitiesasinputreferencesignals,whichisusualwhenregardingcommercialmobilerobots.Itwasconsideredaparameter-updatinglawforthedynamicpartofthecontroller,improvingthesystemperformance.As-modificationtermwasincludedintheparameterupdatinglawtopreventpossibleparameterdrift.StabilityanalysisbasedonLyapunovtheorywasperformedforbothkinematicanddynamiccontroller.Forthelastone,stabilitywasprovedconsideringaparameter-updatinglawwithandwithoutthes-modificationterm.Experimentalresultswerepresented,andshowedthegoodperformanceoftheproposedcontrollerfortrajectorytrackingwhenappliedtoanexperimentalmobilerobot.Along-termsimulationresultwasalsopresentedtodemonstratethattheupdatedparametersconvergeevenifthesystemworksforalongperiodoftime.Theresultsprovedthattheproposedcontrolleriscapableoftrackingadesiredtrajectorywithasmalldistanceerrorwhenthedynamicparametersareadapted.Theimportanceofon-lineparameterupdatingwasillustratedforthecaseswheretherobotparametersare.notexactlyknownormightchangefromtasktotask.ApossibleapplicationfortheproposedcontrolleristoindustrialAGVsusedforloadtransportation,becauseon-lineparameteradaptationwouldmaintainsmalltrackingerroreveninthecaseofimportantchangesintherobotload.一種用于自主移動機器人目標跟蹤的自適應動態(tài)控制器摘要本文提出了一種自適應控制器來指導單輪移動機器人進行軌跡跟蹤。在初始階段，只考慮機器人的運動學模型，即可得到所需的線速度和角速度。然后，對這些值進行處理以補償機器人的動力學，從而生成傳遞給機器人執(zhí)行器的線速度和角速度命令。表征機器人動力學的參數(shù)是在線更新的，因此在這些參數(shù)可以變化的應用中，如負載運輸，提供了更小的誤差和更好的性能。利用李亞普諾夫理論分析了整個系統(tǒng)的穩(wěn)定性，證明了控制誤差是有界的。仿真和實驗結果表明，該控制器在不同負載條件下具有良好的跟蹤性能。1.介紹在不同的移動機器人結構中，由于單環(huán)類平臺具有良好的機動性和簡單的配置，因此常被用于完成不同的任務。針對這類機器人的非線性控制研究已有多年，該機器人結構已應用于監(jiān)視、地板清洗等諸多領域。其他應用，如使用自動導向車輛(AGVs)的工業(yè)負荷運輸，自動公路維護和建設，以及自動輪椅，也使用了獨輪車式的結構。一些作者已經(jīng)解決了軌跡跟蹤的問題，這是一個非常重要的功能，允許移動機器人在完成任務時描述所需的軌跡。agv非線性控制的一個重要問題是，目前設計的控制器大多只基于移動機器人的運動學。然而，當需要高速運動和/或重載運輸時，除了考慮機器人的運動學外，還必須考慮機器人的動力學。因此，提出了一些補償機器人動力學的控制器。Fierro和Lewis(1995)以非完整移動機器人為例，提出了一種考慮建模車輛動力學的運動學/轉矩聯(lián)合控制律，其控制指令為力矩，對于大多數(shù)商用機器人來說，力矩是難以處理的。此外,只報道。仿真結果Fierro和劉易斯(1997)也提出了一個基于神經(jīng)網(wǎng)絡的魯棒自適應控制器來處理干擾和non-modeled動態(tài),雖然不是報告實驗結果。Das和冰斗(2006)顯示一個自適應模糊控制器基于邏輯的模糊邏輯系統(tǒng)估計的不確定性和參數(shù)調(diào)優(yōu)在線。動態(tài)模型包括執(zhí)行器動力學，控制器生成的命令為機器人電機的電壓。神經(jīng)網(wǎng)絡用于辨識和控制，控制信號為線速度和角速度，但其實時實現(xiàn)要求基于多處理器系統(tǒng)的高性能計算機體系結構。另一方面，DeLaCruz和Carelli(2006)提出了一個以線性和速度為輸入的動態(tài)模型，并展示了基于該模型的軌跡跟蹤控制器的設計。其控制器的一個優(yōu)點是其參數(shù)與機器人參數(shù)直接相關。但是，如果參數(shù)識別不正確，或者隨著時間的推移而變化，例如由于負載的變化，會嚴重影響控制器的性能。為了減少性能下降，在線參數(shù)自適應在機器人動態(tài)參數(shù)變化的應用中變得非常重要，例如負載運輸。當動態(tài)參數(shù)的知識有限或根本不存在時，它也很有用。本文提出了一種基于機器人動力學的自適應軌跡跟蹤控制器，并用李亞普諾夫理論證明了其穩(wěn)定性?？刂破鞯脑O計分為兩部分，每一部分都是控制器本身。第一個是基于機器人運動學的運動控制器，第二個是基于機器人動力學的動態(tài)控制器。動態(tài)控制器能夠更新與機器人物理參數(shù)直接相關的估計參數(shù)。這兩個控制器共同工作，形成了一個完整的移動機器人軌跡跟蹤控制器。基于DeLaCruz和Carelli提出的單環(huán)類移動機器人模型設計了控制器，并將s修正項應用于參數(shù)更新律中，以防止可能出現(xiàn)的參數(shù)漂移。證明了運動控制器和動態(tài)控制器的漸近穩(wěn)定性。仿真結果表明，即使系統(tǒng)工作時間較長，也不會產(chǎn)生參數(shù)漂移。實驗結果表明，該控制器具有較強的參數(shù)更新能力，能夠有效地降低跟蹤誤差。實驗結果表明，該控制器能夠在動態(tài)參數(shù)變化的情況下，以較小的誤差引導機器人沿預定軌跡運動。本文的主要貢獻是:(I)使用了一個動態(tài)模型，該模型的put命令中包含速度，這在商用移動機器人中很常見，而文獻中的大部分工作都是關于扭矩命令的;(2)設計了具有修改項的自適應控制器，使其具有魯棒性，并對整個自適應控制系統(tǒng)進行了相應的穩(wěn)定性研究;(3)實驗結果表明，該控制器在典型的工業(yè)應用，即負荷輸送中具有良好的性能。2.動態(tài)模型本節(jié)對DeLaCruz和Carelli(2006)提出的單環(huán)類移動機器人的動力學模型進行了綜述。圖1描述了移動機器人及其感興趣的參數(shù)和變量。u和o線速度和角速度都是由機器人,分別G是機器人的質(zhì)心,C是castor輪的位置,E是一個工具的位置上機器人,h是感興趣的點與XY平面的x和y坐標,C是機器人取向和興趣點之間的距離和中心點的虛擬軸連接牽引輪(B點),寫成完整的數(shù)學模型。分別代表系統(tǒng)的輸入信號。上述移動機器人模型分別與確定的參數(shù)向量和參數(shù)不確定性向量相關聯(lián)，分別為其中dx和dy是滑移速度和機器人方向的函數(shù)，是質(zhì)量、慣量、車輪和輪胎直徑、電機及其伺服參數(shù)、車輪上的力等物理參數(shù)的函數(shù)，被認為是擾動。文中首先給出了參數(shù)h的描述方程，為了方便起見，在此重新給出。他們是需要指出的是，非完整移動機器人必須根據(jù)軌跡軌跡的切線進行定向，才能跟蹤誤差較小的軌跡。否則，控制誤差將會增加。這是真的，因為非完整平臺限制了機器人所發(fā)展的線速度方向。所以，如果機器人的方向與軌跡不相切，那么每一瞬間到目標位置的距離就會增加?？刂普`差收斂到有界值的事實表明，機器人的姿態(tài)不需要顯式控制，在控制誤差較小的情況下與軌跡軌跡相切。3.實驗結果為了驗證該控制器的性能，進行了實驗和仿真。本節(jié)將介紹一些結果。該控制器是在一個先進的3-DX移動機器人上實現(xiàn)的，該機器人以線速度和角速度作為輸入?yún)⒖夹盘?，距離b在圖中。2是零。在第一個實驗中，控制器初始化為一個先鋒2-DX移動機器人的動態(tài)參數(shù)，重約10公斤(通過辨識得到)。兩個機器人如圖3所示，其中先鋒3-DX的平臺上安裝了一個重約6公斤的激光傳感器，這使得它的動力學特性與先鋒2-dx明顯不同。在實驗中，機器人從x=0.2m開始，y=0.0m開始，應遵循參考的圓周軌跡。參考圓的中心在x=0.0m和y=0.8m處。參考軌跡從x=0.8m,y=0.8m開始，沿半徑為0.8m的圓運動。50秒后，參考軌跡突然變?yōu)榘霃綖?.7m的圓。之后，參考軌跡半徑每60秒在0.7~0.8m之間變化。給出了部分實驗機器人軌跡的參考和實際軌跡，其中包括軌跡半徑的變化，在這種情況下，參數(shù)更新是主動的。給出了該控制器在不進行參數(shù)更新的情況下，跟蹤所述參考軌跡的距離誤差。距離誤差定義為參考點到機器人位置的瞬時距離。注意初始誤差很大，這是由于參考軌跡從遠離初始機器人位置的點開始。首先，在不更新參數(shù)的情況下對該控制器進行了測試。從圖5中可以看出，在這種情況下，軌跡跟蹤誤差的穩(wěn)態(tài)值約為0.17m，即使在參考軌跡半徑改變后也沒有變化。該圖還顯示了動態(tài)參數(shù)更新時的距離誤差。通過激活參數(shù)更新，并重復相同的實驗，與ig.3不存在的情況相比，軌跡跟蹤誤差的值要小得多。這些機器人在實驗中使用。4.結論設計了一種適用于單環(huán)類移動機器人的自適應軌跡跟蹤控制器，并對其進行了全面測試?；跈C器人的運動學和動力學模型，將該控制器分為兩部分。側邊紅色的模型以線速度和角速度作為輸入?yún)⒖夹盘?，這在商用移動機器人中很常見。該方法被認為是控制器動態(tài)部分的參數(shù)更新律，提高了系統(tǒng)性能。為了防止參數(shù)漂移，在參數(shù)更新律中加入了s修正項。對運動控制器和動態(tài)控制器進行了基于李雅普諾夫理論的穩(wěn)定性分析。最后，證明了考慮參數(shù)更新律的穩(wěn)定性，其中包含和不包含s修正項。給出了實驗結果，并將該控制器應用于實驗移動機器人的軌跡跟蹤中，取得了較好的效果。仿真結果表明，即使系統(tǒng)工作時間較長，更新后的參數(shù)也會收斂。實驗結果表明，該控制器在動態(tài)參數(shù)調(diào)整的情況下，能夠以較小的距離誤差跟蹤目標軌跡。闡述了機器人參數(shù)在線更新的重要性。不完全知道或可能在不同的任務之間更改。該控制器的一個可能的應用是用于工業(yè)agv的負荷運輸，因為即使在機器人負荷發(fā)生重要變化的情況下，在線參數(shù)自適應也能保持較小的跟蹤誤差。Raspberry

Pi

32016

Raspberry

Pi

3

User

GuideByTedLebowskiCopyright2016TedLebowski-Allrightsreserved.Thisdocumentisgearedtowardsprovidingexactandreliableinformationinregardstothetopicandissuecovered.Thepublicationissoldwiththeideathatthepublisherisnotrequiredtorenderaccounting,officiallypermitted,orotherwise,qualifiedservices.Ifadviceisnecessary,legalorprofessional,apracticedindividualintheprofessionshouldbeordered.-FromaDeclarationofPrincipleswhichwasacceptedandapprovedequallybyaCommitteeoftheAmericanBarAssociationandaCommitteeofPublishersandAssociations.Innowayisitlegaltoreproduce,duplicate,ortransmitanypartofthisdocumentineitherelectronicmeansorinprintedformat.Recordingofthispublicationisstrictlyprohibitedandanystorageofthisdocumentisnotallowedunlesswithwrittenpermissionfromthepublisher.Allrightsreserved.Theinformationprovidedhereinisstatedtobetruthfulandconsistent,inthatanyliability,intermsofinattentionorotherwise,byanyusageorabuseofanypolicies,processes,ordirectionscontainedwithinisthesolitaryandutterresponsibilityoftherecipientreader.Undernocircumstanceswillanylegalresponsibilityorblamebeheldagainstthepublisherforanyreparation,damages,ormonetarylossduetotheinformationherein,eitherdirectlyorindirectly.Respectiveauthorsownallcopyrightsnotheldbythepublisher.Theinformationhereinisofferedforinformationalpurposessolely,andisuniversalasso.Thepresentationoftheinformationiswithoutcontractoranytypeofguaranteeassurance.Thetrademarksthatareusedarewithoutanyconsent,andthepublicationofthetrademarkiswithoutpermissionorbackingbythetrademarkowner.Alltrademarksandbrandswithinthisbookareforclarifyingpurposesonlyandaretheownedbytheownersthemselves,notaffiliatedwiththisdocument.

Effective

use

of

Terminal

commands

Оnе

оf

thе

kеу

а?ресt?

оf

u??ng

а

tеrm?nаl

??

bе?ng

аblе

tо

nаv?gаtе

уоur

f?lеsystem.

Firstly,

run

the

following

command:

ls

-la.

You

should

see

something

similar

to:

The

Is

command

lists

the

contents

of

the

directory

that

you

are

currently

in

or

yourpresent

working

directory.

The

-la

component

of

the

command

is

what's

known

as

a

flag'.Flags

modify

the

command

that's

being

run.

In

order

to

navigate

to

other

directories

thechange

directory

command,

cd

can

be

used.

You

can

specify

the

directory

that

you

want

to

by

either

the

'absolute

or

the

'relative

path.

So

if

you

wanted

to

navigate

to

the

/pidirectory,

you

could

either

do

cd

/home/pi/

or

just

pi

if

you

are

currently

in

/home.

There

aresome

special

cases

that

may

be

useful:

~

acts

as

an

alias

for

your

home

directory,

so~/Desktop

is

the

same

as

/home/pi/Desktop;

.

and

..

are

aliases

for

the

current

directory

and

theparent

directory

respectively,

e.g.

if

you

were

in

/home/pi.Auto-detectcommandRatherthantypeeverycommand,theterminalallowsyoutoscrollthroughpreviouscommandsthatyourunbypressingtheupordownkeysonyourkeyboard.Ifyouarewritingthenameofafileordirectoryaspartofacommandthenthepressingtab:willattempttoAutocompletethenameofwhatyouaretyping.Forexample,ifyouhaveafileinadirectorycalledTestFileNamethenpressingtabaftertyping'T'willallowyoutochoosefromallfileanddirectorynamesbeginningwithaninthecurrentdirectory,allowingyoutochooseTestFileName.SudoprivilegeSomecommandthatmakepermanentchangestothestateofyoursystemrequireyoutohaverootprivilegestorun.Thecommandtemporarilygivesyouraccount(ifyourenotalreadyloggedinasroot)theabilitytorunthesecommands,providedyourusernameisinalistofusers.Whenyouappendsudotothestartofacommandandpressenteryouwillbeaskedforyourpassword,ifthatisenteredcorrectlythenthecommandyouwanttorunwillberunusingrootprivileges.Becareful,thoughsomecommandsthatrequiresudotoruncanirreparablydamageyoursystemsobecareful!InstallSoftwareorotherutilitiesusingapt-getRatherthanusingthePiStoretodownloadnewsoftwareyoucanusethecommandapt-get,thisisthe'packagemanagerthatisincludedwithanyDebianbasedLinuxdistributions(includingRaspbian).ItallowsyoutoinstallandmanagenewsoftwarepackagesonyourPi.Inordertoinstallanewpackageyouwouldtypesudoapt-getinstal<package-name>(where<packagename>isthepackagethatyouwanttoinstall).Runningsudoapt-getupdateupdatesalistofsoftwarepackagesthatareavailableonyoursystem.Ifanewversionofapackageisavailablethensudoapt-getupgradewillupdateanyoldpackagestothenewversion.Finally,sudoapt-getremove<package-name>removesoruninstallsapackagefromyoursystem.FindingthemanualofcommandTofindoutmoreinformationaboutaparticularcommandthenyoucanrunthemanfollowedbythecommandyouwanttoknowmoreabout(e.g.man1s).Theman(ormanualpage)forthatcommandwillbedisplayed,includinginformationabouttheflagsforthatprogramandwhateffecttheyhave.Somemanswillgiveexampleusage.RaspberryPi:GPIOGPIOisoneofthepowerfultoolsofRaspberryPi.YoucaninterfacevarioushardwarewiththeseRaspberryPi.youcanthinkofthemasswitchesthatyoucanturnonorofforthatthePicanturnonoroff.26pinsareGPIOpins,theothersarepowerorgroundpins.Youcanprogramthepinstointeractinamazingwayswiththerealworld.Inputsdon'thavetocomefromaphysicalswitch;itcouldbeinputfromasensororasignalfromanothercomputerordevice,forexample.Theoutputcanalsodoanything,fromturningonaLEDtosendingasignalordatatoanotherdevice.IftheRaspberryPiisonanetwork,youcancontroldevicesthatareattachedtoitfromanywhereandthosedevicescansenddataback.Connectivityandcontrolofphysicaldevicesovertheinternetisapowerfulandexcitingthing,andtheRaspberryPiisidealforthis.WorkingofGPIOIfyouareawareofthefunctionalityofGPIOandhowitisworkingthenmessingaboutwiththeGPIOissafeandfun.GPIOpinscanbeconfiguredaseithergeneral-purposeinput,general-purposeoutputorasoneofupto6specialalternatesettings,thefunctionsofwhicharepin-dependant..Thereare3GPIObanksonRaspberryPi3.Eachofthe3bankshasitsownVDDinputpin.OnRaspberryPi3,allGPIObanksaresuppliedfrom3.3V.TheconnectionofaGPIOtoavoltagehigherthan3.3VwilllikelydestroyordamagetheGPIOblockwithinboardorSoC.GPIOPowerStatesAllGPIOsaresettoinputpinonthepower-onreset.MostoftheGPIOshavethepullupappliedbydefault.InterruptsInterruptsarethemainfeaturesofanyGPIOPinwhichwillenablethepinforfunctioninginamultipleway.Basically,itwillstoptheexecutionofaprogramanddotheotherhighprioritytask.Therearemainly3typesofinterruptsavailablewhichareasfollows:(high/low)Level-sensitive,Risingedgeandfallingedge,AsynchronousrisingedgeandAsynchronousfallingedge.Theinterruptwillworkitstaskuntilthelevelisclearedbythesystemorthetaskofthatinterruptiscompleted.Therisingandfallingedgedetectionwillworkasthedetectionortransitionfromhightoloworlowtohighvoltage.Afterthistransition,theinterruptwilloccurandthecompilerwilljumpintothatparticularinterruptserviceroutine.WhatisInterruptServiceRoutine(ISR)?Itistheroutineorprogramthatwillbeexecutedwhentheinterruptwilloccur.EachinterruptmusthaveitsISRtomakeitstaskcomplete.OtherFunctionsofGPIOAlltheGPIOhasthealternatefunctionaswell.Raspberrypi'sGPIOhasalsosuchfunctionavailable.PinscanactasGeneralPurposeInput/Output,I2CprotocolwhichisusedfortheserialcommunicationwithexternalperipheralslikeEEPROM,otherdevicesetc.SPI(SerialPeripheralInterface)isanotherserialcommunicationprotocolwhichisavailableinRaspberryPI.RandomlypluggingwiresandpowersourcesintoyourPi,however,maydamagetheRaspberryPi.DamagecanalsohappenifyoutrytoconnectthingstoyourPithatusealotofpower.YoucanconnectLEDorsimpleswitcheswithRaspberryPi,ButMotorshavinghighcurrentandotherhighvoltagedevicesmayharmyourboard.Differencefromanotherraspberries1.Cost.AllthreemodelsofRaspberryPicostaround$35.ModelB+waslaunchedinJuly2014wherePi2and3waslaunchedinFebruary2015and2016(ayearapart).AlthoughthePiischeapertherearesomehiddencostswithinvolvedwhenyoubuyone.YouneedaMicroSDCardforloadingtheRaspbianImage,Keyboard,Mouse(Canbewiredorwireless)forcontrollingthepi,HDMIcablefordisplayandawifidongleorEthernetCableforinternetconnectivity.ForRaspberryPi3,thereinanonboardwifimoduleandBluetoothmodule.ThisisanadvantageofbuyingthePi3comparedtopreviousversionsofRaspberryPi.2.PerformanceWhileoperatingat700MHzbydefault,thefirstgenerationRaspberryPiprovidedareal-worldperformanceroughlyequivalentto0.041GFLOPS.OntheCPUleveltheperformanceissimilartoa300MHzPentiumIIof1997--99.TheGPUprovides1Gpixel/sor1.5Gtexel/sofgraphicsprocessingor24GFLOPSofgeneralpurposecomputingperformance.ThegraphicsabilitiesoftheRaspberryPiareroughlyequivalenttotheperformanceoftheXboxof2001.TheLINPACKsinglenodecomputebenchmarkresultsinameansingleprecisionperformanceof0.065GFLOPSandameandoubleprecisionperformanceof0.041GFLOPSforoneRaspberryPiModel-Bboard.Aclusterof64RaspberryPiModel-Bcomputers,labeledIridis-pi",achievedaLINPACKHPLsuiteresultof1.14GFLOPS(n=10240)at216wattsforc.4000US$.RaspberryPi2includesaquad-coreCortex-A7CPUrunningat900MHzand1GBRAM.Itisdescribedas4-6timesmorepowerfulthanitspredecessor.TheGPUisidenticaltotheoriginal.Inparallelizedbenchmarks,theRaspberryPi2couldbeupto14timesfasterthanaRaspberryPi1B+.TheRaspberryPi3,withaQuadcoreCortex-A53processor,isdescribedas10timestheperformanceofaRaspberryPi1.Thiswassuggestedtobehighlydependentupontaskthreadingandinstructionsetuse.BenchmarksshowedtheRaspberryPi3tobeapproximately80%fasterthantheRaspberryPi2inparallelizedtasks.3.CPUModelB+havea700MHzsingle-coreARM1176JZF-Sprocessor.Inthelatermodel,RaspberryPi2havea900MHzquad-coreARMCortex-A7processor.ComparedtotheModelB+,Pi2havemorespeedandmuchmoresuitableformultitaskingbecauseofitsquad-coreprocessor.Intherecentversion,RaspberryPi3,theCPUisa1.2Ghz64-bitquad-coreARMCortex-A53processor.Pi3hasmoreprocessingpowercomparedtoPi2andModelB+andalsoitiscapabletorun64-bitsystems.However,thecurrentversionoftheoperatingsystemsarestill32bit.Inthecomingdaystheremightbeavailabilityof64bitoperatingsystemsforRaspberryPi3.ComparedtotheRaspberryPi2,RaspberryPi3delivers50-60percenthigherperformance.4.RAMOntheolderbetamodelBboards,128MBwasallocatedbydefaulttotheGPU,leaving128MBfortheCPU.Onthefirst256MBreleasemodelB(andmodelA),