SPECOM'006, St. Petersburg, 5-9 Jue 006 Huma-Robot Iteractio: Group Behavior Level Lev Stakevich, Deis Trotsky Sait Petersburg State Techical Uiversity 9, Politechicheskaya, St. Petersburg, 955, Russia de_tr@mail.ru Abstract This paper describes a ew approach to problem of humarobot iteractio for cotrollig behavior of robots group. A solvig this problem is actual for providig teamwork of robots ad other umaed vehicles cotrolled i commad ad cotrol maer. At group level of iteractio, a huma operator ca defie strategy ad tactics of robot teamwork. It is proposed to use special multi-aget 3D game simulatio eviromet (Basketball Server), which provides teamwork of basketball agets uder cotrol of the operator, i order to study priciples of iteractio for huma operator ad robot team. Usig the eviromet, the operator ca chage strategy ad tactics of team operatively usig special aget ad modules embedded ito aget s program, for iteractio with a basketball aget. The eviromet has 3D visualizatio of game. This allows for defiig effectiveess of idividual ad collective behaviors of the agets ad their ability to solve complex tasks of attack ad defese i basketball eviromet. Examples of realizatio ad ivestigatio of differet tactics for teamwork are cosidered.. Itroductio At preset there is large iterest to problem of cotrol for autoomous vehicles performig commo works i group. These ca be mobile robots, participatig i rescue ad military operatios, or umaed vehicles performig various tasks i air, water ad space. These ca be also software robots that are agets solvig idustrial, ecoomical, social tasks cooperatively, or agets playig i soccer or basketball ad participatig i rescue team competitios. Iteractio of huma operator ad robots workig i group is possible at idividual (with every sigle humaoid robot) ad group levels. Curretly iteractio of huma ad humaoid robot is most iterested. The humaoid robots are mobile robots of ew class havig huma-based form ad behaviour. These must be able to act i dyamic ad ot structural eviromet ad to iteract with huma, which ot havig skills of cotrol robots. That s why creatio of friedly huma-robot iterface is critical for effective usig such robots. There are attempts of creatig huma-robot iterface of idividual level based o specialized audio- ad videomeas. I commo case, such meas must allow for detectig huma o a scee, segmet huma s face or hads, to uderstad facial gestures or lip movemet patters correspodig of proouce of words, determie meaig of pose ad gestures of ma, ad kow voice ad speakig message of a perso. However a effective solutio of these tasks is very difficult problem. At the group level the operator ca defie (assig) strategy (type of group behavior ad role of robots) ad tactics (way ad step sequece of behavior realizatio), as well to evaluate quality their realizatio by watchig. At idividual level there is iteractio of huma operator ad sigle robot as a separate act i which the operator forms a message cosistig of istructios (commads) for robot ad checks their executios usig chael of watchig or message from the robot. At the group level of iteractio especial iterest presets a problem of iteractio for operator ad robot group, performig teamwork, requirig carry out commo itetios of all team members to achieve commo goal. I this work it s supposed to use specialized virtual game eviromet for studyig geeral pricipals of such iteractio. This eviromet may be as uiversal mea to model ad to ivestigate iteractio of operator ad robot group i what the robots have complex collective ad idividual behavior. The 3D eviromet for virtual basketball developed provides possibilities to operatively chage strategy ad tactics of robotic aget teamwork. Visualizatio of the game o moitor of computer allows for cotrollig behavior agets of team by the operator. Usage of competitio eviromet provides ivestigatio of differet strategy ad tactics of teamwork ad choosig best of them. Such type of eviromet ca be used ot oly to ivestigate, but also to model cotrol for team of really robots or autoomous vehicles i cetral office of cotrol. It s importat for effective performig rescue, trasport, recoaissace ad military tasks i commad & cotrol systems. Remaider of the paper has followig cotet. I the secod sectio, pricipals of huma-robot iteractio for group robot cotrol system orgaizatio are discussed. I the third sectio of this paper the 3D Basketball Server is described. I the fourth sectio it s show how the basketball agets ca be built. I the fifth sectio experimets related to chage tactics ad strategy are preseted. The work is based o author private experiece o desig of special soccer ad basketball agets for game applicatio [4] ad itelliget cotrol systems of robots [5, 6, 7].. Pricipals of group iteractio humarobot I commad & cotrol systems operator must have possibility to iput istructio for chagig strategy ad tactics teamwork of robots. I this work it is proposed to do it through termial havig specialized program aget-supervisor coected to robots of group. I order to model such system ca be used multi-aget approach [3]. It is allowed for developig multiaget systems that ca be viewed as distributed cotrol 57
SPECOM'006, St. Petersburg, 5-9 Jue 006 systems based o itelliget agets, which iteracts with each other. Curretly the multi-aget techology is ofte used for creatig cotrol system of itellectual robots [5, 6, 7]. I our case a special virtual game eviromet is used. The eviromet cosists of the server ad group of itelligece agets modelig robots. Such eviromet is multi-aget eviromet icludig system of huma-robot iteractio. Structure of huma-robot iteractio system at group behavior level is preseted i fig.. I our system the agets The Commuicatio module provides coectio with cliets, data trasfer over TCP/IP protocol, ad iteractio with the logic module. The Logical module realizes mathematical model of the eviromet. The basic stages of fuctioig of the logical module: Chage of a status of agets i the eviromet; Processig of a simulatio step of the eviromet accordig to a ew status of agets; Preparatio of the sesor iformatio for agets; The Graphical module visualizes objects i the eviromet. The schema of iteractio of modules is preseted i fig.. Fig.. The structure of huma-robot iteractio at group level model the robots ad they are realized as the autoomous cotrol systems with added coordiatio fuctios. Every aget realizes a set of fuctios, which provide idividual ad collective robot s behaviors. The agets are built o the basis of the layered reactive architecture. This architecture allows for doig aget s behavior similar to huma oe. The more complex agets ca be built o the basis of BDI architecture []. Iteractio betwee the agets is determied by its upper level of collective behavior. The special fuctios that realize the coordiatio mechaisms must be used for aget s cooperatio. They provide ability of the agets to be cooperated ad/or competed. I our case it s supposed usig 3D game eviromets of soccer ad basketball for modelig group iteractio operator-robot. For example, i [] a variat of basketball simulatio eviromet called RoboNBA (Natioal Basketball Associatio) was discussed. Ufortuately, this variat use D visualizatio. However i our case, more appropriate is 3D variat. Therefore a developmet of full 3D basketball simulatio is more relevat for our case. Namely such variat of Basketball eviromet was developed to use as modelig oe i the iteractio system. 3. Structure ad compoets of Basketball Server Basketball Server was developed to be the heart of the eviromet for competitio of aget teams. The server was developed i Delphi 7. The server is compatible with OS Widows XP, ad also with other OS of Widows family. It requires Hardware with ot less tha 64MB RAM, GHz CPU speed, 0 Mb free disk space. 3.. The structure of the server The server icludes Commuicatio, Logical, ad Graphic modules. Fig.. The scheme of iteractio of Server modules 3.. Model of the eviromet The eviromet cosists of the court, two basket rigs with backboard, ball ad 0-players. The size of the court is xmax by ymax (fig. 3). Fig, 3. Model of eviromet The positio of each player is defied i 3D space: P = { p i }, () where pi - ( x i, yi, zi ). The positio of the ball is also defied i 3D space: 57
SPECOM'006, St. Petersburg, 5-9 Jue 006 Ball = { x, y, z} (3) The ball may have status FREE (the ball is free) ad BUSY (the ball is take by player). The player is idetified by the umber of its team as TeamID = {0, } ad by player umber i the team - PlayerID = {,,3,4,5 }. 3.3. Actio model I the server, the time is update i discrete steps. A simulatio step is 00 ms. The server ca process the limited umber of actios that defied as commads set by a player (oe commad of each player is executed for oe step of time): SHOOT (power Pow, directio DirXY ad DirZ). The player shoots the ball with the power Pow, i directio of horizotal plae DirXY ad i directio of vertical plae DirZ. PASS (power Pow, directio DirXY ad DirZ). The player passes the ball with power Pow, i directio of horizotal plaes DirXY ad i directio of vertical plae DirZ. The ball, movig with the power Pow i directio DirXY ad DirZ, is switched i state «FREE». RUN (power Pow). The player rus with power Pow i curret directio.. TURN_DIRECTION (directio DirXY). The player chages its body directio to Dir XY. CATCH. The player captures the ball. If distace betwee the ball ad the player is less tha CatchableDist, the ball belogs to the player. If more the oe player is withi distace CatchableDist to the ball, the ball will go to the earest player. Catch actio is executed oly whe the ball is free. BLOCKSHOOT. Player blocks shoot or pass of oppoet. 3.4. Model of movemet Positio of the player with coordiates {x, y, z }, power pow, ad a directio DirXY i the ext simulatio step is calculated as follows: x y z = x + pow*cos( dirxy * Pi /80) = z = y + pow*si( dirxy * Pi /80) where { x, y, z } is the ew coordiates of the player. Positio of the ball with coordiates x, y, }, power { z pow, directio DirXY ad DirZ i the ext simulatio step is calculated i the followig way: dirz Pi dirxy Pi x = x + pow cos( ) cos( ) 80 80 dirz Pi dirxy Pi y = y + pow cos( ) si( ) 80 80 zspeed = zspeed GRAVITY z = z + zspeed (4) (5) where { x, y, z} is the ew coordiates of the ball, GRAVITY is the acceleratio of free fallig, zspeed is the vertical speed of the ball, calculated i the momet of shoot or pass by the formula (6). zspeed = pow * si( dirz * Pi /80) (6) 3.5. Sesor model The server ca sed the followig iformatio to players: Ow coordiate; Coordiates, TeamID, PlayerID, DirXY parameters of all parters ad oppoets; Coordiates ad status of the ball, TeamID ad PlayerID of player, who cotrols the ball, if status of the ball is BUSY. 3.6. Structure ad compoets of the program of the server The server is implemeted as object-orieted program. The program of the server cosists of the followig modules: Mai.pas is the Commuicatio module, which performs the start of the TCP/IP server, orgaizes coectio ad data trasfer to cliets; Eviromet.pas is the Logic module, which realizes mathematical model of the eviromet, simulates of actios of agets ad movemets of a ball; DGraph.pas is the Graphic module, which cotais fuctios for graphic display of the eviromet; Basket.pas is the file of the descriptio of protocol ad commads of the server; Costats.pas is file cotaiig costats of the server; 4. The basketball aget To provide complex idividual ad collective behaviors at teamwork, the basketball agets must be built usig multi layered architectures. The basketball aget has three-level architecture that is similar to the soccer aget architecture used i [4]. Note, that oe of the variats of the aget with described architecture was used for creatio of the soccer aget of team STEP (Soccer Team of ElectroPult) that has became by wier of World Champioship RoboCup-004 i Simulatio D Soccer League. The low level of the basketball aget has several executive reactive layers. Number of the layers ca be chaged at aget s behavior tuig. Each executive layer has its priority ad reacts to give situatio by formig the correspodig actios i respose o iput iformatio. Set of such reactios defies some primitive executive behaviors (aget s skills). Sequece of the selected reactios correspods to curret itetio of the aget. The middle level of the aget has set of productio rules defiig idividual behavior of the aget. These rules use the coditios i form of data, facts, ad situatios that are kow for the aget. They carry out decisios for selectio of primitive behaviors that must be realized at low level of the aget. The upper level of the aget also has set of productio rules that form correspodig collective aget s behavior. At this level the aget first makes decisio o selectio of 573
SPECOM'006, St. Petersburg, 5-9 Jue 006 whether idividual or collective behavior. If the aget selects a collective behavior, the it must take ito accout positios of parters ad oppoets. I case of arisig coflicts the curret collective behaviors of agets are formed. The coflict is solved usig special rules for coformig aget s actios. Aget has module of iteractio with operator. This module receives commads of operator through the Server ad accordig to oe chage tactics ad strategy of behavior of aget. For example, operator ca poit out agets that it s log throwig, if oppoet mark agets ot dese o 3 poit lie. I this case, module of iteractio chage set of productio rule of upper level. 4.. Structure of the aget The structure of the aget is preseted i fig. 4. 4.. Tactics of the aget At the secod level a player could make decisio o attack, defese, or catch the ball. The goal of the team i the attack is to score a ball i a basket rig. The goal of the team i the defese is to ot allow the oppoets to fiish the attack. There are some variats of the orgaizatio of the defese. I the give example a persoal markig of players is used. Durig the defese, players have the followig tasks: To block the free movig oppoet to the basket; To itercept the ball while oppoet passes; I the attack, it is ecessary to solve the followig tasks: To deliver the ball to oppoet basket; To perform a accuracy shoot; Catchig ball actios should take ito accout first of all a status of the ball ad positio of the player related to the ball. At the team tactic level the player makes a decisio o curret actio i the team. Formally algorithm of decisio makig is described as (7): (( BALL = FREE) ( t ( Go to else ( t Fig.4. Architecture of aget get the ball) else ( Go back to the defese half ) 0 t ) ( t t ) ( Go to the attackhalf ) 0 t )) (7) where t0 is distace betwee the player ad the ball, t is distace betwee the ball ad parter earest to the ball, t is distace betwee the ball ad oppoet earest to ball. The give algorithm is the same as described i []. If the ball is busy, the player has two optios (8): (( BALL= BUSY) ( BALLTeamId = PlayerTeamId)) ( Go to get the ball) (( BALL= BUSY) ( BALLTeamId PlayerTeamId)) ( Go to the attackhalf) where BALLTeamId is umber of team, who cotrols the ball, PlayerTeamId is umber of player i the team. Attack actios. Goal of the team i attack is to score the ball i the basket rig. First it is ecessary to deliver the ball up to the basket of oppoet. The ball ca move o the court usig two of the ways: ) Player rus with ball; ) Player passes the ball to parter; Two selectio strategies ca be used such as selectio of parter earest to oppoet basket rig ad selectio of parter, whose positio is optimal. The algorithms implemetig these strategies are described i detail i []. Optimality of the positio of each of parters o the court is described by some value. This value is amed a evaluatio of the player. Whe a player eeds to pass the ball, he selects teammate with the highest evaluatio. Evaluatios of all parters are defied i followig way: t = f d ) + g( d m ) m, d m < ε (8) ( (9) where d is the distace betwee th teammate ad basket; d m is the distace betwee th teammate ad mth oppoet; f (x) is a fuctio that evaluates the goodess to shoot for the teammate; g (x) is a fuctio that evaluates the threat from oppoets. Whe parter is defied, ball s trajectory is calculated. Iitial parameters of a pass are calculated such a way that the ball has ot bee itercepted by oppoet ad the give parter will be the first player who ca itercept the ball. ) The horizotal directio of the ball is defied as: DirXY = ArcCos(( Parter. x Aget. x) Dist( Parter, Aget))*80 / Pi if ( Parter. y < Aget. y) the ( DirXY = DirXY) (0) where DirXY is horizotal directio of pass; Parter is the coordiate of the parter who receives the pass; Aget is the 574
SPECOM'006, St. Petersburg, 5-9 Jue 006 coordiate of the parter which passes; Dist is fuctio defiig distace betwee two poits o a court. ) Defiitio of rages of chage of iitial parameters of a pass is made as follows: Pow =..30 DiZ = 40..75 Time = 0..50 () where Pow is the power of pass, DiZ is the vertical speed of pass, Time is cout of time steps. 3) Iitial ball s parameters are calculated as: x = Aget. x y = Aget. y z = PlayerHeight Vz = Pow*si( DirZ * Pi /80) where Ball is the coordiate of the ball; PlayerHeight () is the costat of the server defiig height of the player; Vz is vertical speed of the ball. 4) The ball s parameters are calculated as follows with time: Vz = Vz G DirZ Pi DirXY Pi x = x + Pow cos( ) cos( ) 80 80 DirZ Pi DirXY Pi y = y + Pow cos( ) si( ) 80 80 z = z + Vz (3) where G is acceleratio of free fallig; 5) A hit of the ball i the give zoe is defied usig the followig coditio: Dist ( Ball, Parter) < CatchableDist (4) Coordiates of a ball ad iitial parameters of a pass are saved as: BallFial = Ball MiDirZ = DirZ MiPow = Pow (5) 6) Search of the earest BallFial to the parter is realized by the followig way: MiDirZ, MiPow 0 (6) where = Mi( BallFial Parter) Parameters MiDirZ, MiPow are selected, at which distace betwee the ball ad parter is the least oe. Graphic iterpretatio of the give algorithm is preseted i fig. 5. The give algorithm builds several trajectories of a throw (curves,, 3 i fig. 5) ad chooses oe of them, which is closer to the parter. I case show i fig.5, such curve is the trajectory 3. This algorithm also calculates parameters of shoot to the basket rig. Defese actios. As defesive strategy, the persoal markig of players is used. The player i chooses of the oppoet j for markig if the coditio (7) is satisfied. PlayerID i = PlayerID j (7) Further it is ecessary to choose a positio o a field, to which the player should move to mark the oppoet. Coordiates of this positio are calculated by the formula (8): P = ( P + ( P CircleOw)/ ))/ (8) i j j + Fig. 5. Miimizatio of pass parameters where P j is coordiate of the jth oppoet; CircleOw is coordiate of the ow basket rig; P i is required positio. P i is the poit located as a midpoit likig oppoet ad midpoit, likig oppoet ad the basket rig. If player is closer to the oppoet, the markig player will be closer to him. At the momet of a pass or a throw whe the ball is switched i a status FREE, the markig player ca make iterceptio of the ball. If it was possible, the the player is switched to attack, else player is switched to defese. 5. Experimets o strategy ad tactics ivestigatio Experimet was directed to ivestigatio of teamwork effectiveess usig hadlig team strategy ad tactics by operator i real time. Attack ad defese strategies were examied. Ad tactics of pass ad dribble were also examied. For example, the two fuctios of selectio of a parter for a pass were cosidered (see sectio 3.4): ) Fuctio of earest parter (selectio of parter earest to oppoet basket rig); ) Fuctio of optimal positio (selectio of parter, whose positio is optimal). Efficiecy of each system of a pass was estimated through tactical ad techical parameters of each team. The tactical ad techical parameters iclude: the score, poits throws (success/all), 3 poits throws (success/all), pass (success/all), accuracy of a pass (%), possessio of a ball (%). To ivestigate efficiecy of each system was made match of two teams, each of which uses oe of fuctios of a pass. Team A used the fuctio of optimal positio, ad the Team B used the fuctio of earest parter. I fig. 6 the fragmet of game is show. 575
SPECOM'006, St. Petersburg, 5-9 Jue 006 results of experimets with differet roles of agets ad pass fuctios have showed real possibility of icreasig effectiveess of teamwork by correctio of strategy ad tactics for teams. I the future it s supposed to develop huma-aget iteractio modules for improvemet of aget s idividual ad collective behaviors i real time. Also it s supposed to ivestigate possibility of strategy maagemet i order to implemet improvig aget s teamwork. It s also plaed to implemet special module of hadlig sceario behavior by operator i order to do more effective aget s tactics. Fig. 6. Experimetal match I the table the tactical ad techical parameters of experimet are preseted. Table. Experimet results Parameters Team А Team В Score 0 5 poits throws (suc. / all) / 8 / 3 poits throws (suc. / all) / 7 / Pass (suc. / all) 33 / 64 0 / 65 Accuracy of a pass (%) 5 3 Possessio of a ball 5 48 Several evaluatios ca be cocluded from this table. Number of the passes ad accuracy of the pass: the higher parameters i accuracy of a pass for the Team A are caused by usig the fuctio of optimal positio; this fuctio first of all prefers those players, who mark of the oppoet less, ad hece probability that the ball will be itercepted will be less. Possessio of the ball: the higher parameter i possessio of the ball for the Team A is cosequece of the superiority i accuracy of a pass. The team better plays a pass because it more holds the ball. The score ad throws: Team A has demostrated better game i a pass; therefore it has advatage i the score as well as throws. The Team B oly 3 times has fiished the attack with a throw o a basket rig while the Team A has executed 5 throws. Low accuracy of a throw of the Team A has ot allowed havig cosiderable advatage i the score. The give algorithm of throws was ot foud effective sice i the result of experimet the low parameter of accuracy of a throw was obtaied. 7. Refereces [] Bratma M.E., Israel D.J., ad Pollack M.E. Plas ad resource-bouded practical reasoig. I Computatioal Itelligece, #4: 349-355, 988. [] Bigche Hu, Jimig Liu, Xiaolog Ji. From local behaviors to global performace i a multi-aget RoboNBA system. I Proceedig of IEEE/WIC/ACM Iteratioal Coferece o Itelliget Aget Techology (IAT 004, Beijig), 004, pp. 309-34. [3] Gorodetski, V.I. ad Lebedev, A.N. Multi-aget Techology for Plaig, Schedulig, ad Resource Allocatio. I Third It. Cof. o Multi-Aget Systems, Paris, Frace, 998. [4] Stakevich, L.A. A cogitive aget for soccer game. Proceedig of First Workshop of Cetral ad Easter Europe o Multi-aget Systems (CEEMAC'99), Prited by "Aatolyi", S-Petersburg, 999. [5] Stakevich L.A. Multiaget techology i cogitive cotrol systems for autoomous robots. «Extreme robotics. Proceedig of X-th Coferece, St. Petersburg», St. Petersburg STUPress, 999 (i Russia). [6] Stakevich L.A. Cogitive robotics. «Extreme robotics. Proceedig of XII-th Coferece, St. Petersburg», St. Petersburg STUPress, 00 (i Russia). [7] Stakevich L.A. Cogitive structures ad agets i itellectual robot cotrol systems. AI News #, 004, pp. 4-55 (i Russia). 6. Coclusios Basketball Server was developed to be eviromet for ivestigatio of possibility for hadlig basketball aget team strategy ad tactics i real time. Usig the proposed architecture ad the developed algorithms of behavior, the basketball agets were developed ad ivestigated. Developed behavioral fuctios based o set of rules ad module of huma-robot iteractio has allowed for operative chagig tactics i attack ad defese of the teams. The 576