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A C ase Stud y o f LEG O Min dst orm s 'TM Su i tab i l i ty fo r Ar ti f ic ia lIn te l l igence and Rob ot ics Cou rses a t the Co l leg e Leve l

Frank KlassnerDepartment of Computing Sc iences

Vil lanova UniversityVil lanova, PA 19085Frank.Klassner@vi l lanova.edu

A b s t r a c tThis paper examines LE GO Mindst orms TM suitability as ahardware platform for integrating robotics into an ArtificialIntelligence course organized around the agent paradigmpopularized by Russell and Norvig. This evaluationdiscusses how kits and projects based on Mindstormssupported students' exploration of the issues behind thedesign of agents from three classes in Russell and Norvig'sintelligent agent taxonomy. The paper's investigation alsoexamines several popula rly-pe rceive d limitations of theMindstorms package for college-level robotics projects andshows that most o f these "limitations" are not seriousimpediments to Mindstorms' use, while certain other ofthese "limitations" do indeed present challenges to theplatform's u s e .1 In t roduc t ionRecent publications show that robotics-oriented problemscan be used successfully as a pedagogical tool forgrounding abstract topics in certain computer sciencecourses (e .g. in t rod uctory programm ing [7 ,10] ) Inparticular, Kumar and Meeden showed [5] that it wasfeasible to use a combination of the HandyBo ard [6] andLEGO building blocks as the basis for an effective roboticlaboratory for artificial intelligence (AI) course topics atundergraduate liberal arts institutions. Since the late 1990's,several undergraduate computer science and computerengineering programs [3] have started robotics labs builtaround the HandyBoard/LEGO combinat ion or theActiv Media platform [1 ].In 1996 LEGO Ine released the Mindstorms robotdevelopment and programming ki t for middleschoolstudents. Though related to the HandyBoard's design, theMindstorms platform has not been explored as a viableplatform for college-level projects until quite recently [4].Permission to make digital or hard c op i e s o f all or part of this work forpersonal or classroomuse is granted without fee provided that copies arenot made or distributed for profit or commercial advantage and thatcopies bear this notice and the full citation on the first page. To copyotherwise, or republish, to post on servers or to redislribute to fists,requires prior specific permission and/or a fee.SIGCSE'02, February27- March 3, 2002, Covington,Kentucky, USA.Copyright 2002 ACM 1-58113-473-8/02/0002...$5.00.

Review of recent SIGC SE and ITiCSE li terature alsoshows a lack of study of Mindstorm's suitabil i ty forsupporting AI pedag ogy. Popular justifications for thissituation have included the kit 's small number of sensorsand effectors, a lack of sophist ic ated prog ramm ingenvironment, and a lack of support for common college-level programming languages such as Java and C.These observations did indeed represent serious obstaclesto Mind stor ms' use in AI courses at the time of theplatform 's release. Howev er, during the last four years anactive Mindstorms hobbyist community has arisen on theInternet and has produced a large, informal bod y of work( e .g . deve loped p r og r amming env i r onmen t s andexperimented with sensor-management techniques at theplatform's bytecode prog ramming level) to ameliorate someof these and other perceived s hortcomings.In addition to this development, two practical reasonsrecommend that the Mindstorms platform be re-examinedfor viability in college-level artificial intelligence projects: A single Mindsto rms kit costs approx imatel y $200 andthus is one-quarter the cost of a HandyBoard-basedrobot kit and one-tenth the cost of an ActivMedia-based rob ot kit. The Mindstorm s kit is a suite of reusable snap-togethesensors (touch, rotation, light, temperature), effector(motors, lights, infrared emitters) building blocks, anda programmable control unit that can serve as the basisfor a wide variety of robotics projects. Platforms oequivalent price to Mindstorms often require solderingand other one-shot construction methods that maketheir reuse across course offerings economicallyimpractical.For these reasons, this paper reports on a two-trackinvestigation into the Mindstorms platform's suitability fointegrating robotics into two semester offe rings of theVillanova University AI course organized around the agenparadigm popularized by Russell and Norvig [11]. The firstrack examines the sophistication of the robotics projectthat the course kits supported. It also examines severapopularly-perceived limitations of the Mindstorms packagefor college-level robotics projects and shows that many o

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t h e s e " l i m i t a t io n s " a r e n o t s e ri o u s i m p e d i m e n t s t oMind s tor ms ' use , w hi le ce r ta in o the r o f these " l imi ta t ions"do indeed s t il l p r esen t cha l lenges to the p la t f or m ' s use . Thes e c o n d i n v e s t i g a t i o n t r a c k e x a m i n e s t h e p e d a g o g i coutcome s obse r ved f r om s tudent eva lua tions .A s b a c k g r o u n d f o r i n t e r p r e t i n g t h e p r o j e c t s a n dM i n d s t o r m s ' e v a l u a t i o n s , t h is p a p e r f i r st d e s c r ib e s t h es tudents w ho pa r t i c ipa ted in the CSC 4500 of f e r ings , thec o u r s e ' s r e l a t i o n s h i p t o o t h e r c o u r s e s i n t h e V i l l a n o v ac o m p u t e r s c i e n c e p r o g r a m , a n d t h e L E G O e q u i p m e n t u s e db y t h e s t u d en t s . T h e p a p e r t h e n d e s c r i b e s t h e L E G Opr ojec t s and s tudent pe r f or mance . The la s t tw o sec t ions ofthe paper d i scuss the obse r ved s t r engths and l imi ta t ions oft h e M i n d s t o r m s p l a t f o r m a n d c o u r s e p r o j e c t s a n d p r o p o s eguide l ines f or us ing the p la t f or m in o the r envi r onments

2 Student Backgrounds and Course ContextT h e e l e c t i v e A I c o u r s e a t V i l l a n o v a ( C S C 4 5 0 0 ) h a s n of o r m a l p r o g r a m m i n g p r e r e q u i s i t e s . . C o m p u t e r s c i e n c em a j o r s t y p i c a l l y t a k e C S C 4 5 0 0 i n t h e i r f o u r t h y e a r , b yw h i c h t i m e m o s t c o m p u t e r s c i e n c e m a j o r s h a v e t a k e n aP r o g r a m m i n g L a n g u a g e s c o u r s e t h a t b r i e f l y i n t r o d u c e sthem to L isp , the l anguage mos t o f ten used in CSC 4500.The cour se i s a l so open to cogni t ive s c ience minor s andc o m p u t e r e n g i n e e r s , w h o g e n e r a l l y h a v e n o p r o g r a m m i n gexper ience in L isp and a t mos t one semes te r o f in t r oduc tor yp r o g r a m m i n g i n J a va .The cour se of f e r ings examined in th i s paper w er e he ld inFall 1999 and Spr ing 2001.

3 Minds t or ms Equipme ntF r o m t h e o u t s e t , r o b o t i c s p r o j e c t s i n C S C 4 5 0 0 w e r ein tended to be t eam- based ac t ive - lea r n ing pr o jec t s . Eacht e a m ' s k i t f o r c o n s t r u c t i n g L E G O r o b o t s c o n t a i n e d t h ef o l low ing ha r dw ar e :

( a ) 3 Minds tor ms Robot ic I nvent ion Sys tems packages(b) 3 mo re l ight sensors beyo nd the three in (a)( c ) 3 mor e touch sensor s beyon d the six in (a )( d) 3 mor e motor s beyond the s ix in (a )(e) 2 rotat ion sensors( f ) 24 recharge able bat ter ies( g) 1 l a r ge lockable too lbox to ho ld a l l o f the abov e as

w el l a s a pa r t i a l ly - comple ted r obot .A s e a r c h w a s c o n d u c t e d f o r a C o m m o n L i s p p r o g r a m m i n ge n v i r o n m e n t f o r M i n d s t o r m s , b u t n o n e c o u l d b e f o u n d f o rthe Fa l l 1999 of f e r ing . Each team in tha t o f f e r ing the r e f or eu s e d t h e N Q C ( N o t Q u i t e C ) p r o g r a m m i n g e n v i r o n m e n td e v e l o p e d b y D a v i d B a u m [ 2] t o p r o g r a m t h e i r ro b o t s. T h elanguage has C syntax , bu t l acks the f o l low ing C f ea tur es :po in te r s ; r ecur s ive pr ocedur a l invoca t ion , and pr ocedur esw i t h re t u rn v a l u es o r p a r a m e t e r s . N Q C c o m p e n s a t e s f o r

t h e l a c k o f p r o c e d u r e s u p p o r t w i t h a m a c r o d e f i n i t i o nfaci l i ty for " inl ine procedures ."N Q C w a s s e l e c t e d f o r u s e in C S C 4 5 0 0 i n s p i t e o f it sm i s s i n g C f e a t u r e s b e c a u s e i t d i d p r o v i d e a h i g h - l e v e lMind s tor ms A PI tha t s tudents could qu ick ly l ea rn , a l low ingt h e m t o d e v e l o p c o n t r o l p r o g r a m s t h a t w e r e m u c h m o r es o p h i s t i c a t e d t h a n t h o s e a c h i e v a b l e t h r o u g h t h e L E G O -s u p p l i e d G U I p r o g r a m m i n g e n v i r o n m e n t . N Q C a l s opr ovid ed s tudents w i th a mor e pow er f u l A P I f or us ing theMinds tor m s ha r d w ar e ' s mu l t i th read ing capabil i t ie s .T h e S p r i n g 2 0 0 1 o f f e r i n g a l s o u s e d N Q C a s t h e p r i m a r ypr ogr amming too l , a l though a pr imi t ive L isp in te r pr e te r f o rr e m o t e l y c o n t r o l l i n g M i n d s t o r m s r o b o t s w a s u s e d i n o n epr o jec t ( s ee pr o jec t V I in Sec t ion 4) .

4 Course ProjectsIn both course offerings students worked on a number oft e a m p r o j ec t s , s o m e b a s e d o n M i n d s t o r m s a n d N Q Cc o d i n g , o t h e r s b a s e d o n L i s p c o d i n g . T h e f o l l o w i n gMinds tor ms- based pr o jec t s were d e v e l o p e d f o r t h e c o m e :L Simple-Reflex Robot Design. T h i s 1 - w e e k p r o j e c t ' s g o a lw a s t o s h o w s t u d e n t s h o w r o b o t s w i t h s i m p l e s t i m u l u s -r esponse r u les and a ve r y l im i ted mode l o f the envi r onment( the second- s imples t des ign in Russe l l and N o r v i g ' s agen tdes ign taxonom y) could ach ieve e f f ec t ive behavior s .This p r o jec t a sked s tudents to des ign a r obot based on at r e a d - w h e e l e d " ' P a t h f i n d e r " m o d e l d e s c r i b e d i n L E G O ' suse r manua l . S tudents w er e r equi r ed to s ta rt w i th th is bas icd e s i g n i n o r d e r t o r e d u c e t i m e s p e n t o n d i s t r a c t i n gm e c h a n i c a l e n g i n e e r i n g i s s u e s , b u t t h e y w e r e e n c o u r a g e dto mount sensors as needed.S tudents f i rs t bu i l t a r obot tha t r an a r ando m w alk , ignor inge n v i r o n m e n t a l s t i m u l i . T h e w a l k c o n s i s t e d o f t r a v e l i n gf o r w a r d f o r a r a n d o m n u m b e r o f s e c o n d s, t h e n r a n d o m l ytur n ing 30 degr ees l e f t o r r igh t , and r epea t ing these tw oa c t i o n s f o r e v e r . W e t h e n r a n t h e s e f i r s t - s t a g e r o b o t sthr ough a shor t obs tac le cour se w i th na r r ow passages , andt imed the i r p r ogr es s.S tudents nex t added one or mor e th r eaded ta sks to moni tore i t h e r ( a ) w h e t h e r , v i a f e e d b a c k f r o m t h e M i n d s t o r m s 'bu i l t - in in f r a r ed sensor or mounted l igh t s ensor s , a r obot i stoo c lose to a w a l l , o r ( b ) w he the r , v ia f eedback f r omm o u n t e d l i g h t o r t o u c h s e n s o r s a r o b o t w a s w e d g e d i n ac o r n e r . T h e m o n i t o r t a s k w a s t o o v e r r i d e t h e d e f a u l tr a n d o m w a l k b y t u r n i n g 3 0 d e g r e e s a w a y f r o m t h eobse r ved s t imulus ( e i the r l e f t o r r igh t , a s neces sa r y) . W ethen a l low ed these second- s tage r obots to r un in the s ameo b s t a c l e c o u r s e , a n d s t u d e n t s o b s e r v e d a s i g n i f i c a n t( t h o u g h n o t a s l a r g e a s t h e y g e n e r a l l y e x p e c t e d ! )impr ovement .1I. Sensor Accuracy and Functional Simulation. T h i spr o jec t ' s goa l w as to show s tudents how ( in) sens i t ive eachof the i r s ensor s w er e to va r ious s t imul i , and to d i sco verhow some sensors can s imula te o the r s ensor s ' capabi l it i e s .

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T h e f i rs t p a r t o f t h e p r o j e c t r e q u i r e d e a c h t e a m o f s t u d e n tsto expose the i r s ensor s ( touch , l igh t, in f r a r ed , and r o ta t ion)t o a s w i d e a v a r i e t y o f s t i m u l i a s t h e y c o u l d g e n e r a t e t ol e a r n th e r a n g e o f m e a n i n g f u l r e s p o n s e v a l u e s t h e s e n s o r sc o u l d g e n e r a t e . T h e y w e r e a l s o a s k e d t o e x p l o r e w h a tr e s p o n s e s w e r e g e n e r a t e d w h e n t w o o r m o r e s e n s o r s w e r ec o n n e c t e d t o t h e s a m e i n p u t p o r t . T h e e x p e r i e n c e s s t u d e n t sg a i n e d i n t h i s p r o j e c t w e r e i n v a l u a b l e i n h e l p i n g t h e md e c i d e h o w t o c h o o s e a n d a r r a n g e s e n s o r s o n r o b o t s f o r t h em o r e c o m p l i c a t e d p r o j e c t s d e s c r i b e d l a te r .T h e s e c o n d p a r t o f t h e p r o j e c t a s k e d t e a m s t o d e s i g n s i m p l er obots tha t used on ly touch , in f r a red , and/o r l igh t s ensor s tod u p l i c a t e t h e a c c u r a c y a n d s e n s i t i v i t y o f r o t a t i o n s e n s o r s .T h i s d u p l i c a t i o n e f f o r t w a s i n t e n d e d t o f a m i l i a r i z e s t u d e n t sw i t h t h e c o n c e p t o f f u n c t i o n a l e m u l a t i o n - a k e y c o n c e p t i nu n d e r s t a n d i n g h o w a b s t r a c t A I t o o ls l i k e p la n n e r s a n dsea r ch a lgor i thms can ( pa r t i a l ly ) emula te each o the r .I l l . Robot Odometry . T h i s 2 - w e e k p r o j e c t ' s g o a l w a s t oh e l p s t u d e n t s u n d e r s t a n d t h e m a j o r f a c t o r s t h a t c a ni n t r o d u c e e r r o r i n t o a r o b o t ' s i n t e r n a l r e p r e s e n t a t i o n o fw h e r e i t b e l i e v e s i t c u r r e n t l y l o c a t e d i n t h e w o r l d - a ni m p o r t a n t i s s u e i n a n y n a v i g a t i o n p r o c e s s .E a c h t e a m w a s r e q u i r e d t o d e s i g n a n d b u i l d a r o b o t t h a tw o u l d m e a s u r e t h e p e r i m e t e r o f a b l a c k s h a p e o n a li g h tb a c k g r o u n d o n t h e f l o o r. T h e r e p o r t e d m e a s u r e m e n t ( o v e r1 6 0 c m ) h a d t o b e a c c u r a t e t o w i t h i n + / - 5 c m , a n d h a d t ob e o b t a i n e d w i t h i n 6 m i n u t e s f r o m t h e t i m e t h e ro b o t w a ss t ar t ed . T h e p r o j e c t a l l o w e d u s e o f d e a d - r e c k o n i n g a n dl a n d m a r k - b a s e d n a v i g a t i o n t e c h n i q u e s . A l t h o u g h a l l t e a m ss u c c e e d e d i n t h i s p ro j e c t , a l l w e r e s u r p r i s e d a t h o w s h o r tt h e 6 - m i n u t e t i m e l i m i t s o o n a p p e a r e d i n l ig h t o f th eaccur acy cons t r a in t .IV . Capture - the -Bal l s Contes t . T h i s 1 - m o n t h p r o j e c t ' s g o a lw as to he lp s tudents t i e the sk i l l s they deve loped in pr o jec t sI - I I I w i t h s e a r c h - s t a t e - b a s e d a n d h i l l - c l i m b i n g - b a s e d a g e n td e s i g n s ( t h e th i r d l e v e l o f R u s s e ll a n d N o r v i g ' s t a x o n o m y ) .E a c h t e a m w a s r e q u i r e d t o d e s i g n a n d b u i l d a r o b o t n ol a r g e r t h a n 1 c u b i c f o o t . T h e r o b o t ' s t a s k w a s t o p l a y i n a4 5 - m i n u t e c o n t e s t ( b a s e d o n [ 3 ] , b u t a d a p t e d t o f i tM i n d s t o r m s ' c a p a b i l i t i e s) a g a i n s t o t h e r t e a m s ' r o b o t s .Contes tan t s had to p lay in a 20x9 sq . f t . w a l led p lay ing a r eain w hich each team had a 1 sq . f t . nes t a r ea , co lor ed da r kp u r p l e . A l l o t h e r p o r t i o n s o f t h e p l a y i n g f i e l d w e r e l i g h t -y e l l o w c o l o r e d . S c a t t e r e d t h r o u g h o u t t h e f i e l d w e r e b l a c k ,w h i t e , a n d y e l l o w p i n g p o n g b a l ls . F o r e a c h b a l l t h a t w a s i na t e a m ' s n e s t a t t h e e n d o f t he c o n t e s t, t h e f o l l o w i n g p o i n t sw e r e a w a r d e d : w h i t e + 1 , y e l l o w + 5 , b l a c k - 1 . T h e p l a y i n gf i e ld w a s m a r k e d w i t h a b l a c k l x l - f o o t g r i d w h o s e l in e sw e r e 1 c m w i d e .T e a m s w e r e e n c o u r a g e d t o t r y a w i d e v a r i e t y o f g a m es t r at e g i e s, s o m e o f w h i c h r e q u i r e d l a n d m a r k - b a s e dn a v i g a t i o n v i a t h e g r i d, o t h e r s o f w h i c h r e q u i r e d s t a t e - s p a c eh i l l - c l i m b i n g , a n d s t il l o t h e r s o f w h i c h r e l i e d o np r o b a b i l i s t i c o b s e r v a t i o n s a b o u t t h e e n v i r o n m e n t . T e a m sw e r e a l s o e n c o u r a g e d t o m a k e t h e i r u s e o f s t r a te g i e s t i m e -

d e p e n d e n t : a s t h e c o n t e s t p r o g r e s s e d , r o b o t s c o u l d s w i t c hs t r a teg ies based on the i r cur r en t s ta te ( e . g . e s t ima ted scor e ,p o s i t i o n o n fi e l d) . S i n c e ro b o t s w e r e p e r m i t t e d t o " a t t a c k "o the r nes t s and sca t te r o r s tea l ba l l s , the r e w as a ve r y w idev a r i e t y o f a p p r o a c h e s t h a t a t e a m c o u l d e x p l o r e ,m i n i m i z i n g t h e r i sk o f t e a m s u n i n t e n t i o n a l l y d u p l i c a t i n gtheir ef for ts .V. Team-based Capture - the -Bal l s . T h i s 1 - m o n t h p r o j e c tw a s t h e s a m e a s p r o j e c t I V , e x c e p t t h a t e a c h s t u d e n t t e a mw a s a l l o w e d t o f i e l d u p t o t h r e e r o b o t s a s a t e a m . T h i sp r o j e c t ' s p e d a g o g i c g o a l w a s t o h e l p s t u d e n t s u n d e r s t a n dt h e i s su e s b e h i n d t h e d e s i g n o f c o o p e r a t i v e , c o m m u n i c a t i n gagents .VI . Robot i c 8-Puzz le Solver . T h i s 2 - w e e k p r o j e c t h a d t h eg o a l o f s h o w i n g s t u d e n t s t h a t k n o w l e d g e r e p r e s e n ta t i o n s( d a t a a b s tr a c t i o n s ) t h a t s p e e d u p s e a r c h - b a s e d p r o b l e ms o l v e r s c a n p r o d u c e s o l u t i o n r e p r e s e n t a t i o n s t h a t a x e n o te a s i l y t ra n s l a t e d i n t o c o n t r o l p r o g r a m s f o r h a r d w a r e .T h e p r o j e c t h a d t w o s t a g e s . I n t h e fi r s t s t a g e s t u d e n t s h a dt o d e v e l o p a k n o w l e d g e r e p r e s e n t a t i o n a n d L i s p s e a r c hp r o g r a m t o s o l v e t h e 8 - P u z zl e . T h e t e a m d e v e l o p e d a s e to f fo u r o p e r a t o rs t h a t i n v o l v e d c o n c e p t u a l l y m o v i n g t h e"space" up , dow n, l e f t , o r r igh t , r a the r than 32 oper a tor s f orm o v i n g e a c h o f t h e n u m b e r e d t i le s u p , d o w n , l e f t , o r fi g h t .T h e s t u d e n t s o b s e r v e d t h a t t h is d e s i g n d e c i s i o nd r a m a t i c a l l y r e d u c e d t h e b r a n c h f a c t o r o f t h e s e a r c h t r e e ( 4v s . 3 2 ), l e a d i n g t o a fa s t e r e x e c u t i o n t i m e f o r th e g a m e -so lve r .Th e seco n d s ta g e req u ired s tu d en t s to wr i t e a seco n d Li spp ro g r a m th a t in v o k e d fu n ct io n s in an a d h o c l ib ra ryd e v e l o p e d b y t h e i n s tr u c t o r t o s e n d r e m o t e - c o n t r o lm e s s a g e s t o a M i n d s t o r m s r o b o t ic a r m m e c h a n i s m( d e s i g n e d b y t h e i n s t r u c t o r - c o n s t r u c t i o n d e t a i l s a v a i l a b l eu p o n r e q u e s t ) t o m o v e p i e c e s i n a n 8 - P u z z l e a c c o r d i n g t ot h e s o l u t i o n d e v e l o p e d b y s t a g e l ' s p r o g r a m m i n g . I t w a s i nt h i s s t a g e t h a t s t u d e n t s d i s c o v e r e d t h a t t h e s e a r c h s p a c er e f o r m u l a t i o n t ri c k u l t i m a te l y c o s t t h e m i n t h e c o m p l e x i t yo f t he t r a n s la t i on t h e ir s e c o n d p r o g r a m h a d t o p e r f o r m o nt h e " m o v e s p a c e " o p e r a t o r l i st to " m o v e t il e a t ( 2 , 2 ) t o( 2 ,1 ) '" t y p e s o f c o m m a n d s .

5 Course OrganizationT h e F a l l 1 9 9 9 o f f e ri n g h a d 1 7 s tu d e n t s : 1 5 c o m p u t e rs c i e n c e m a j o r s , l p h y s i c s m a j o r , a n d 1 c o m p u t e re n g i n e e r i n g m a j o r . P r o j e c t s I - V d e s c r i b e d i n S e c t i o n 4 w e r ea s s i g n e d t o 6 t e a m s ( t h r e e t e a m s o f 3 a n d t w o t e a m s o f 4) .T h e S p r i n g 20 0 1 o f f e r i n g h a d o n l y 4 s t u d e nt s : 3 c o m p u t e rs c i e n c e m a j o r s , a n d 1 c o g n i t i v e s c i e n c e m i n o r ( p s y c h o l o g ym a j o r ) . T h e r e d u c e d c l a s s s i z e l e d t h e i n s t r u c t o r t o d e c i d et o m a k e a l l f o u r s t u d e n t s w o r k o n a s i n g l e t e a m w h o s eP r o j e c t M a n a g e r p o s i t i o n r o t a t e d a m o n g t h e m e m b e r s f o re a c h p r o j e c t. I n t h is o f f e r i n g t h e t e a m w o r k e d o n P r o j e c t V Iand I I I (in tha t o r de r ) . The sma l l s i ze in the s eco nd of f e r ingi s a t t r i b u t a b l e t o t w o f a c t o r s : o u r d e p a r t m e n t o f f e r e d f i v ee l e c t i v e c o u r s es t h a t s e m e s t e r i n s t e a d o f th e u s u a l f o u

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( l ead ing to a d i lu t ion of s tudents ac r os s a l a r ge r numb er o fc o u r s e s ) a n d t h e S p ri n g 2 0 0 1 C S C 4 5 0 0 o f f e r i n g w a ss c h e d u l e d a s a n e v e n i n g c o u r s e ( w h i c h h i s t o r i c a l l y h a v edepr es sed enr o l lments a t V i l l anova) . To addr es s po ten t ia lr e a d e r c o n c e r n s t h a t t h e c o u r s e ' s w o r k l o a d o r d e s i g nunduly d i scour aged s tudents f r om s ign ing up , i t should ben o t e d t h a t a s o f N o v e m b e r 20 0 1 t h e r e a r e 2 4 s t u d e n ts( c o m p u t e r s c i e n c e , a s t r o n o m y , m e c h a n i c a l e n g i n e e r i n g ,b io logy , and compute r enginee r ing major s ) enr o l led f or theSpr ing 2002 of f e r ing of the cour se ( one of 4 CSC e lec t ivesavai lable , in a la te-morning t ime-s lot) .

6 S t u d e n t a n d P r o j e c t Ev a lu a t io nA s s e e n i n s t u d e n t s ' p e r f o r m a n c e o n e x a m i n a t i o np r o b l e m s , t h e r o b o t p r o j e c t s d i d g i v e t h e m a s t r o n gu n d e r s t a n d i n g o f t h e c o n c e p t s h i g h l i g h t e d i n t h e p r o j e c tgoa l s in Sec t ion 4 . I n t imed ex ams s tudents w er e asked todesc r ibe ho w ( ha r dw ar e or sof tw ar e ) age nts in a l l o f theRusse l and N or v ig t axonomy ( inc lud ing those no t expl ic i t lye x p l o r e d i n r o b o t p r o j e c t s ) m i g h t b e r e a l i s t i c a l l yi m p l e m e n t e d fo r v a r i o u s e n v i r o n m e n t s . T h i s t y p e o fa b s t r a c t q u e s t i o n w a s g e n e r a l l y p o o r l y a n s w e r e d i n C S C4500 of f e r ings pr ior to Fa l l 1999 . I n the tw o r obo t - or ien tedof f e r ings s tudents s cor ed 20% higher .B a s e d o n o t h e r e x a m q u e s t i o n s , s t u d e n t s i n t h e r o b o t i c -b a s e d C S C 4 5 0 0 o f f e r i n g s w e r e a b l e t o d e m o n s t r a t e t h e i ru n d e r s ta n d i n g o f t he c o n c e p t o f " e m e r g e n t b e h a v i o r " b e t t e rw i t h v e r y c o n c r e t e r o b o t i c e x a m p l e s t h an those in ea r l i e rof f e r ings . To be ob jec t ive , how ever , i t mus t be no ted tha tr o b o t i c s s t u d e n t s w e r e m o r e s u s c e p t i b l e t o m a k i n g t h em i s t a k e o f b e l i e v i n g t h a t " e m e r g e n t b e h a v i o r " o n l y r e f e rst o b e h a v i o r t h a t a r i s e s f r o m e r r o r s i n t h e i n t e r a c t i o nb e t w e e n p i e c e s o f a c o m p l e x s y s t e m r a t h e r t h a n an ybehavior ( pos i t ive or nega t ive ) tha t a r i s es f r om in te r ac t ionsb e t w e e n p i e c e s o f a c o m p l e x s y s t e m .A l t h o u g h i t is n o t a s t a t ed g o a l o f t h e A I c o u r s e , t h emul t i t a sk ing pr ogr ams tha t s tudents w r o te in the r obot ic s -b a s e d o f f e r i n g s g a v e t h e m m u c h m o r e c o n f i d e n c e i nw o r k i n g w i t h m u l t i t h r e a d i n g i s s u e s , a c c o r d i n g t o c o u r s eexit surveys (10 of 21) .A l l s t u d e n t s u r v e y r e sp o n d e n t s , w h i l e g e n e r a l l y v i e w i n gt h e r o b o t i c s p r o b l e m s a s p o s i t i v e i n f l u e n c e s o n t h e i rl ea r n ing , f e l t tha t the A I cour se should be expanded to a 4 -c r ed i t ( 4 - hour /w eek) cour se to be t te r r e f lec t the w or k load .A l a r g e n u m b e r ( 1 6 o f 2 1) o f s tu d e n t s u r v e y r e s p o n d e n t sa l s o i n d i c a t e d t h a t t h e i r i m p r e s s i o n o f t h e d i f fi c u l t y o fsens ing the envi r onment and cor r ec t ly in te r pr e t ing sensor s 'e n v i r o n m e n t a l m e a s u r e m e n t s w a s m i x e d : h a l f fe l t th ep r o b l e m w a s m o r e d i f f i c u l t b e c a u s e t h e L E G O s e n s o r sw er e inaccur a te , w hi le the o the r ha l f f e l t tha t the pr oblem st h e y h a d e n c o u n t e r e d w e r e j u s t i n d i c a ti v e o f t h e n a t u re o fthe gener a l s ensor in te r pr e ta tion pr oblem .A l o n g t h e s a m e l i n e s o f " h a r d w a r e e v a l u a t i o n , " 1 2 o f t h e2 1 s u r v e y r e s p o n d e n t s f e l t t h a t m o r e p l a n n i n g s h o u l d b edone by the ins t r uc tor to r educe the t ime compu te r s c ience

s t u de n t s s p e n d o n d e s i g n o f r o b o t c h a s s i s. W h e n a s k e d t or a t e t h e i r a g r e e m e n t w i t h t h e s t a t e m e n t " T h e d e s i g n o fha r dw ar e f or an in te l l igen t agent i s eve r y b i t ( i f no t mor e )i m p o r t a n t a s t h e d e s i g n o f so f t w a r e f o r a n i n t e l l i g e n ta g e n t , " a t t h e b e g i n n i n g o f t h e r o b o t i c s c o u r s e s , t h er espon dents ' ave r age w as 5 .7 (1 be ing s t r ongly d i sagr ee , 10be ing s t r ongly agr ee ) . A f te r the cour se th i s s ame ques t ionr ece ived an a ver age agr eem ent l eve l o f 7 .1 .Based on these obse r va t ions f r om the ( admi t ted ly smal l ) s e tof s tudents in the tw o cour se of f e r ings , I a r gue tha t ther o b o t i c s p r o j e c t s w e r e a m o r e p o s i t i v e t h a n n e g a t i v einf luence on s tudents ' l ea r n ing of A I concepts , and a mor ep o s i t i v e t h a n n e g a t i v e i n f l u e n c e o n s t u d e n t s ' a p p r e c i a t i o no f th e i s s u es b e h i n d d e s i g n o f " h a r d w a r e + s o f t w a r e " a g e n ts .

7 M i n d s to rm s Ev a l u a t i o nW hile one may be ab le to conc lude tha t th i s r epor t ' s p r o jec te v a l u a t i o n s l e n d s o m e m o r e s u p p o r t t o t h e c l a i m t h a tr o b o t i c s - o r i e n t e d p r o b l e m s c a n b e u s e d s u c c e s s f u l l y a s ap e d a g o g i c a l t o o l f o r g r o u n d i n g a b s t r a c t t o p i c s i n c o m p u t e rscience courses (at leas t , in ar t i f ic ia l intel l igence) , severalq u e s t i o n s m u s t b e a d d r e s s e d b e f o r e o n e c a n c l a i m t h a tL E G O M i n d s t o r m s i s a g o o d p l a t fo r m f o r s u p p o rt i n gpr o jec t s o f enough sophis t i ca t ion to pr oduce these benef i t s.A c o m m o n l y - c i t e d c r i t i ci s m o f M i n d s t o r m s f o r u s e i nc o l le g e c o u r se s i s t h a t L E G O ' s G U I - b a s e d p r o g r a m m i n gsuppor t f o r the p la t f or m i s too gr ade- school o r ien ted . W h i let r u e , I a s s e r t t h a t t h e e x i s t e n c e o f p r o g r a m m i n ge n v i r o n m e n t s s u c h a s N Q C a n d R C X - A d a [ 4 ] c o u n t e r t h i sp r o b l e m r e a s o n a b l y we l l. I n t h e s u m m e r s in c e th e S p r i n g2 0 01 c o u r s e o ff e ri n g , o p e n - s o u r c e p r o g r a m m i n ge n v i r o n m e n t s f o r th e J a v a [ 9 ] , C + + [ 8 ] , a n d L i s p [ 1 2]l a n g u a g e s h a v e b e e n d e v e l o p e d f o r t h e M i n d s t o r m sp l a t f o r m . T h e s e l a n g u a g es s h o u l d m a k e M i n d s t o r m s m o r ee a s i l y i n t e g ra t a b l e i n to a n y p r o g r a m m i n g - o r i e n t e dc o m p u t e r s c i e n c e c o u r s e a s a n a l t e r n a t i v e p l a t f o r m f o re x p l o r in g p r o g r a m m i n g p r o b l e m s .A n o t h e r c o m m o n c r i t i c is m o f t h e M i n d s t o r m s k i t is t h a t itdoes no t a l low one to bu i ld sophis t i ca ted r obots . I ndeed , i tm i g h t s e e m t h a t t h e f a c t t h a t t h i s p a p e r ' s o w n r o b o t i c stoo lbo x ( Sec t ion 3) needed the conten t s o f th r ee ind iv idua lMind s tor ms k i t i s ev ide nce in f avor of th i s c la im . I has tent o c l a r i f y t h is p r o b l e m b y o b s e r v i n g t h a t t h e o n l y p r o j e c ttha t r equi r ed the mate r ia l in mor e than one k i t w as P r o jec tV - T e a m - b a s e d C a p t u r e - t h e - B a l l s . I t w a s , in fa c t ,an t ic ipa t ion o f th i s p r o jec t tha t l ed to the expan s ion o f thebas ic t eam too lbox .I do accept the c r i t i c i sm tha t the Minds tor ms k i t does no tc o n t a i n a n a d e q u a t e n u m b e r o f s e n s o rs t o s o l v e s o m ein te r es t ing pr oblem s . I n pa r t icu la r , the r o ta t ion sensor ( aka"angle s ensor " ) i s c r uc ia l to any r obus t so lu t ions to ther o b o t i c n a v i g a t i o n p r o b l e m , y e t i t i s n o t i n c l u d e d i n t h eb a s i c M i n d s t o r m s k i t. I h i g h l y r e c o m m e n d t h a t a n y o n ec o n t e m p l a t i n g u s e o f M i n d s t o r m s f o r c o l l e g e ro b o t i c spr o jec t s add th i s s ensor to the ir deve lop ment budge t !

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7/28/2019 A Case Study of LEGO Mindstorms

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W h i l e i t i s a l s o t r u e t h a t th e M i n d s t o r m s ' p l a t f o r m o n l ysuppor t s th r ee input por t s , th i s does no t l im i t the p la t f or m ' ss e n s o r y c a p a b i l i t y a s m u c h a s i t w o u l d s e e m . I n m ye x p e r i e n c e a n d m y s t u d e n t s ' e x p e r i e n c e , i t i s p o s s i b l e t o" s t a c k " m o r e t h a n o n e t o u c h o r l i g h t s e n s o r o n t h e s a m ep o r t a n d t o i n t e r p r et t h e p o r t ' s m e a s u r e m e n t s a p p r o p r i a t e l y .T h a t i s , b y c o n f i g u r i n g ( t h r o u g h a n N Q C p r o g r a m ) a p o r t t ob e i n " r a w m o d e , " o n e w i l l o b t a i n a n i n t e g er v a l u e b e t w e e n0 an d 1 0 2 4 t h a t c a n b e a n a l y z e d t h r o u g h r e p e a t e de x p e r i m e n t a t i o n t o d e t e r m i n e w h e n o n e , t w o , o r n o s e n s o r so n t h e s a m e p o r t h a v e b e e n a c t i v a t e d . I n s o m e s i t u a t i o n st h a t I w i l l d i s c u s s i n m y l e c t u r e , o n e c a n e v e n d e t e r m i n ew hich pa r t i cu la r s ensor in a s tack has been ac t iva ted .W h e n o n e i s r e s t r i c t e d t o u s i n g t h e f i r m w a r e s u p p l i e d b yL E G O i n a M i n d s t o r m s r o b o t , I b e l i e v e fr o m m yexper iences tha t i t i s a va l id c r i t i c i sm tha t cont r o l p r ogr amsar e somew hat l im i ted in s ize and capabi l i ty . P r imar i ly , th i si s d u e t o t h e f i r m w a r e ' s l a c k o f s u p p o r t f o r a p r o c e d u r e c a l ls t a c k a n d d y n a m i c m e m o r y a l l o ca t i on . H o w e v e r , n o w t h a tt o o l s s u c h a s L e J O S ( a n a t i v e J a v a V i r t u a l M a c h i n e f o rM i n d s t o r m s ) [ 9] a n d L e g O S ( a C + + k e r n e l f o rMin ds tor m s) [ 8] ex i s t, th i s c r i t i c i sm has l e s s v igor .I t i s s t i l l a v a l i d c r i t i c i s m a s w e l l t o c l a i m t h a t t h eM i n d s t o r m s ' 3 2 K B o n b o a r d m e m o r y r e p re s e n t s a s e ri o u sr es t r i c t ion f or a r t i f i c ia l in te l l igence ins t r uc tor s ( l ike myse l f )w h o w a n t t o g i v e s t u d en t s e x p e r i e n c e i n w o r k i n g w i t h r e a l -t i m e s c h e d u l e r s a n d p l a n n e r s s i t u a t e d w i t h i n r o b o t s . O n ep o s s i b l e s o l u t i o n t o t h is p r o b l e m w o u l d i n v o l v e d e s i g n i n g af r a m e w o r k t h a t o f f l o a d s m o s t o f t he c o m p u t a t i o n i n t h e ses y s t e m s t o a d e s k t o p , a n d t h e n p e r i o d i c a l l y i s s u e s r e m o t e -c o n t r o l c o m m a n d s t o t h e M i n d s t o r m s r o b o t .A major c r i t i c i sm I do agr ee w i th i s tha t the p la t f or m ( and ,f o r n o w , e v e n o p e n - s o u r c e e n h a n c e m e n t s ) d o e s n o t s u p p o r tuse f u l w i r e les s p r o tocols over i t s bu i l t - in in f r a r ed por t . A l lM i n d s t o r m s p r o g r a m m i n g e n v i r o n m e n t s t h a t d e p e n d o n t h es t a n d a r d L E G O f i r m w a r e a r e l i m i t e d t o u s i n g a b r o a d c a s tp r o t o c o l t h a t d o e s n o t s u p p o r t t a r g e t e d m e s s a g e - p a s s i n ga m o n g r o b o t t e a m s o r b e t w e e n a c e n t ra l c o n t r o l d e s k t o pa n d a r e m o t e l y - c o n t r o l l e d s e t o f r o b o ts . T h i s w a s a s e r io u sp r o b l e m f o r s tu d e n t s w o r k i n g o n P r o j e c t V .A p e r s o n a l c r i t i c i s m m y s t u d e n t s a n d I h a v e i n r e g a r d s t ou s i n g t h e M i n d s t o r m s p l a t f o r m i n m y L i s p - b a s e d A I c o u r s ew a s t h a t b e c a u s e t h er e w a s n o C o m m o n L i s p p r o g r a m m i n ge n v i r o n m e n t f o r t h e p l a t f o r m , m y s t u d e n t s h a d t h e a d d e do v e r h e a d o f l e a rn i n g N Q C i n a d d i ti o n t o L i s p . H o w e v e r ,w i t h n e w d e v e l o p m e n t s i n W i c k e t a l . ' s L e g o / S c h e m ec o m p i l e r [ 1 2] a n d m y o w n f u t u r e w o r k i n a L i s pM i n d s t o r m s r e m o t e - c o n t r o l l i b r a r y , I e x p e c t t h i s c r i t i c i s mto d i sappear soon .

8 Conclusion s and Future WorkBase d on the sophis t i ca t ion of the pr o jec t s in Sec t ion 4 andthe obse r va t ions in Sec t ion 6 and Sec t ion 7 , I c la im tha t theL E G O M i n d s t o r m s p l a t f o r m ha s g r o w n s i n c e i tsi n t r o d u c t i o n t o b e c o m e a c o s t - e f fe c t i v e p l a t f o r m w o r t h y o f

c o n s i d e r a t i o n b y a n y s m a l l c o l l e g e a s a c o m p l e m e n t a r yp r o g r a m m i n g e n v i r o n m e n t to t ra d t io n a l P C p r o g r a m m i n g .A s m o r e w o r k i s d o n e i n t h e o p e n s o u r c e c o m m u n i t y t oa m e l i o r a t e t h e u n a d d r e s s e d c r i t i c i s m s i n S e c t i o n 7 , t h eM i n d s t o r m s p l a t f o r m ' s p e d a g o g i c a l v i a b i l it y w i l l o n l yimpr o ve . To th i s end , I p lan to w o r k on ex tendin g the bas icL E G O f i r m w a r e t o i n cl u d e s u p p o r t f o r t a r g e t e d m e s s a g e -p a s s i n g a n d t o d e v e l o p a s y s t e m f o r d is t r i b u ti n gc o m p u t a t i o n w i t h i n a r o b o t i c n e t w o r k .A c k n o w l e d g m e n tT h i s m a t e r i a l i s b a s e d u p o n w o r k s u p p o r t e d b y t h e N a t i o n a lS c i e n c e F o u n d a t i o n u n d e r G r a n t N o . 0 08 8 8 8 4 . A n yo p i n i o n s, f i n d i n g s , a n d c o n c l u s i o n s o r r e c o m m e n d a t i o n se x p r e s s e d i n t h i s m a t e r i a l a r e th o s e o f th e a u t h o r a n d d o n o tneces sa r i ly r e f lec t the v iew s of the N SF .

References[ 1] A c t i v M e d i a R o b o t i c s , h t t p : / / w w w . a c t i v r o b o t s . e o m[ 2 ] B a u m , D . N o t Q u i t e C ( N Q C ) , J u n e 2 0 0 1 ,h t t p : / / w w w . e n t e r a c t . e o m / - d b a u m / n q e / i n d e x . h t m l[ 3] Beer , R . D . , Chie l , H . J . , and D r ushe l , R . F . "U s inga u t o n o m o u s r o b o t i c s t o t e a c h s c i e n c e a n d e n g i n e e r i n g , "Communications of the ACM, V ol . 42 ( 6) June 1999 , pp . 85- 92.[ 4] Fagin , B . , Mer k le , L . , and Egger s , T . "Teaching bas icc o m p u t e r s c i e n c e c o n c e p t s w i t h r o b o t i c s . " I n Proceedingsof the 32 "a SIGCS E Technocal Symposium on ComputerScience Education (2001).[ 5 ] K u m a r . D . , a n d M e e d e n , L . A r o b o t l a b o r a t o r y f o rteach ing a r t i f i c ia l in te l l igence . I n Proceedings of the 29 hSIGCSE Technical Symposium on Computer ScienceEducation (1998).[ 6] M a r t i n , F . , T h e M I T H a n d y B o a r d P r o j e c t , 2 0 0 0 .h t t p : / / l c s. w w w . m e d i a . m i t . e d u / g ro u p s / e l / P r o j e c ts / h a n d y -board/ , Sept . 6, 2001.[ 7] M a z u r , N . a n d K u h r t , M . " T e a c h i n g p r o g r a m m i n gc o n c e p t s u s i n g a r o b o t s i m u l a t i o n , " J o u r n a l o f C o m p u t i n gin Small Colleges , Vol . 12, (5) 1997, pp. 4-11.[ 8 ] N o ga , M a r k u s . L e g O S , J u n e 2 0 0 1 ,h t t p : / / w w w . n o g a . d e / l e g O S[ 9] S o l o r z a n o , J o s e . L e j O S , M a y 2 0 0 1 ,h t tp : / / l e jos . sour ce f or ge . com[ 10] S te in , L . A . , I n te r ac t ive pr ogr amming: r evolu t ion iz ingi n t r o d u c t o r y c o m p u t e r s c i e n c e , " A C M C o m p u t i n g S u r v e y s2 8 A ( 4 ) , D e c e m b e r 1 9 9 6 .[ 11] Russe l l , S . and N or v ig , P . Artificial Intelligence: AModern Approach. Prentice Hall , 1995.[ 1 2] W i c k , A . , K l i p s c h , K . , a n d W a g n e r , M .L E G O / S c h e m e c o m p i l e r , v . 0 . 52 , ( J u n e 2 0 0 1 )h t t p : / / w w w . c s . i n d i a n a . e d u / - m t w a g n e r / l e g o s c h e m e /

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