Hybridplay: a New Technology to Foster Outdoors Physical Activity, Verbal Communication and Teamwork

sensors

Article HybridPLAY: A New Technology to Foster Outdoors Physical Activity, Verbal Communication and Teamwork

Diego José Díaz 1, Clara Boj 2 and Cristina Portalés 3,* 1 Industrial Systems Engineering and Design Department, Universitat Jaume I, Castelló de la Plana 12071, Spain; [email protected] 2 Fine Arts Department, Universidad de Murcia, Murcia 30800, Spain; [email protected] 3 Institute of Robotics and Information and Communication Technologies, Universitat de València, València 46010, Spain * Correspondence: [email protected]; Tel.: +34-963-543-557

Academic Editors: Fabrizio Lamberti, Andrea Sanna and Jon Rokne Received: 31 December 2015; Accepted: 20 April 2016; Published: 23 April 2016

Abstract: This paper presents HybridPLAY, a novel technology composed of a sensor and mobile-based video games that transforms urban playgrounds into game scenarios. With this technology we aim to stimulate physical activity and playful learning by creating an entertaining environment in which users can actively participate and collaborate. HybridPLAY is different from other existing technologies that enhance playgrounds, as it is not integrated in them but can be attached to the different elements of the playgrounds, making its use more ubiquitous (i.e., not restricted to the playgrounds). HybridPLAY was born in 2007 as an artistic concept, and evolved after different phases of research and testing by almost 2000 users around the world (in workshops, artistic events, conferences, etc.). Here, we present the temporal evolution of HybridPLAY with the different versions of the sensors and the video games, and a detailed technical description of the sensors and the way interactions are produced. We also present the outcomes after the evaluation by users at different events and workshops. We believe that HybridPLAY has great potential to contribute to increased physical activity in kids, and also to improve the learning process and monitoring at school centres by letting users create the content of the apps, leading to new narratives and fostering creativity.

Keywords: entertainment; physical activity; video games; children; playgrounds; ubiquitous

1. Introduction Game-based technologies for entertainment and/or edutainment are not only for adults, but a great market exists centered on the early ages. A recent study [1] reveals that 38% of children under the age of 2 have used a mobile device for playing games, watching videos or other media-related purposes. By the age of 8, 72% of children have used a smartphone, tablet or similar device. By contrast, the use of playgrounds, ballparks, etc. decreases from the age of 6, which contributes to reduced physical activity and increased childhood overweight/obesity and creates a rift with children’s social environment. From the social point of view, games are proven learning mechanisms—fundamental at early ages—to acquire skills and abilities such as communication and social interaction, and especially to be temporarily transformed into “other” people and acquire the ability to understand the view of the “other”, and thus substantially enhance our ability to understand the world and how to access it [2]. Although these beneﬁts are evident in traditional games, in video games the problem is that their prolonged use can potentially lead to develop some addictions, especially in the so-called massive multiplayer online role-playing games, with the consequent risk of isolation and inability of children to develop social and communicative relations in the physical space; especially when children and

Sensors 2016, 16, 586; doi:10.3390/s16040586 www.mdpi.com/journal/sensors Sensors 2016, 16, 586 2 of 21 adolescents, which are used to communicate through avatars in the digital networks, online games and virtual communities, have to do so in person [3–7]. Therefore, we understand that some video games can potentially generate a social and communicative isolation, everything unlike traditional games developed in public spaces such as catch, hide-and-seek, hopscotch, etc., where children have to communicate verbally and physically with each other. Different researchers and developers have dealt with one or some of these problems from different perspectives, e.g., by contributing to promote a healthier lifestyle with the development of technologies and media games that foster physical activity through the game, or by reducing the social break with the development of multiuser and collaborative games. In this sense, we can mention some game platforms such as Nintendo Wii and the games Wii Sport or Wii Balance Board, that revolutionized the gaming world by requiring users to physically exercise while playing or by converting them into personal trainers. Also, the Wii remote controller has been used by the research community to develop other applications and to investigate novel human-computer interactions [8–11]. A more recent example is Kinect, a range-based sensor from which many applications in the areas of entertainment and edutainment have been developed [12–15]. These platforms promote both physical activity and collaborative gaming, thus contributing positively to address the aforementioned problems. However, these platforms are still intended to be played indoors and require the use of other equipment such as a TV screen, and thus are not able to comprise the whole problem, as these facts restrict children’s playing freedom. On the other hand, other research works and commercial solutions exist that merge playgrounds with virtual worlds, and thus promote physical activity outdoors. For instance, the interactive installation Water Games [16], is an excellent example of interactive outdoor gaming in which different dynamics are developed among large groups of users and where intensive multi-user interaction occurs. Another example is the Reactive Active Playground initiative [17]. In this research, new interaction and game systems were developed, which highlight the value that game systems designed with an open nature have for kids [18]. In such systems, a rich and dynamic partnership of children with the playing device occurs, because they personalize it with their own design of a game mechanism around the technological device and, at the same time, the game encourages their intellectual and creative development. Other similar examples are the Playware [19] and InnoPlay [20] projects. At the market level, the company Playnetic [21] offers a variety of products that allow interaction with different elements of the playground. To that end, they have created some elements with integrated technology that incorporate sound stimuli and that allow kids to, e.g., chat with each other, maintain songs playing while jumping in a stone, listen to stories after spinning a pendulum to generate energy in a storyball, etc. There exists other commercial solutions, such as Kompan Icon [22], i-play [23], Neos 360 [24,25] or Sona [26]. In all of them, the technology forms part of the elements of the playground. Finally, we would like to mention one of our previous projects called Zona de Recreo [27], first released in 2001, which consists of a multi user interactive platform arising from the transformation of a saucer swing that incorporates audiovisual digital technologies. The individual or collective use of this physical game interface, which we call video swing, allows the user to interact with a 3D virtual game by using the motion of his/her body. This application can be seen as one of the first solutions that incorporated technology (video games) in playgrounds. Building upon the growing development of ubiquitous technologies and distributed computing, in our research we propose a paradigm shift by integrating the two media (virtual and physical) and generating smart, enhanced environments that engage children and youth to develop their physical and socio-communicative skills through a new game-based technology incorporated in the playgrounds. In this paper we present HybridPLAY, a novel technology that brings together the best of both worlds: firstly, it offers the full potential of the digital gaming industry (leisure linked to learning), and secondly it fosters outdoor physical activity (e.g., at playgrounds), without forgetting the collaborative (face-to-face) interaction. HybridPLAY is a new technology that enhances the urban space, opening new avenues for fun and gaming. Differently from the aforementioned solutions that merge playgrounds with virtual worlds, HybridPLAY is not integrated in the elements of the Sensors 2016, 16, 586 3 of 21 Sensors 2016, 16, 586 3 of 20 playground,merge playgrounds but attached with to virtual them. In worlds, this way, HybridPLAY kids can carry is not the integ HybridPLAYrated in the sensor elements andplay of the with ourplayground, proposed technologybut attached notto them. only In at this every way, park, kids butcan alsocarry outside the HybridPLAY them (e.g., sensor in the and classroom, play with at home,our proposedetc.). technology not only at every park, but also outside them (e.g., in the classroom, at home, etc.). 2. Materials and Methods 2. Materials and Methods The HybridPLAY platform transforms playgrounds into interactive, game scenarios (Figure1). This is achievedThe HybridPLAY with a network platform of transforms wireless sensors playgrounds that, attached into interactive, to playground game scenarios elements, (Figure transforms 1). themThis into is achieved physical with interfaces a network that of wireless control sensors video that, games attached (or apps) to playground integrated elements, in mobile transforms devices. Thethem sensors into registerphysical the interfaces kids’ movements that control while video playing games on(or the apps) swings, integrated slides, in see-saws, mobile devices.etc., which The are transformedsensors register into actionsthe kids’ that movem controlents the while digital playing game: on walk, the swings, jump, run,slides, turn, see- beat,saws,etc. etc.,HybridPLAY which are combinestransformed physical into actions and digital that control interaction the digital to create game: outdoor walk, jump, gaming run, experiences turn, beat, etc. by HybridPLAY mixing digital combines physical and digital interaction to create outdoor gaming experiences by mixing digital game strategies with street game dynamics, verbal and corporal communication and team playing. game strategies with street game dynamics, verbal and corporal communication and team playing. Thus, with the HybridPLAY platform we aim at fostering outdoor physical activity and enhance Thus, with the HybridPLAY platform we aim at fostering outdoor physical activity and enhance communication and teamwork among players. Technically, HybridPLAY consists of a distributed communication and teamwork among players. Technically, HybridPLAY consists of a distributed network of sensors, easily adaptable to the gaming furniture of the playgrounds. These sensors network of sensors, easily adaptable to the gaming furniture of the playgrounds. These sensors wirelesswireless communicate communicate with with a a server server that that handleshandles the communication between between them them and and the the gaming gaming terminalsterminals with with which which children children can can access access thethe digitaldigital world. In In this this way, way, we we have have created created a set a set of oftools tools thatthat transform transform playgrounds playgrounds by by means means of of aa rapid,rapid, non-intrusivenon-intrusive and and reversible reversible way. way.

Figure 1. HybridPLAY workflow. Figure 1. HybridPLAY workflow. While designing the sensorial elements of HybridPLAY, the following five key points have been takenWhile into designing account: the sensorial elements of HybridPLAY, the following five key points have been taken into account: 1. Versatile placement: the sensors can be easily placed on any playground element without 1. Versatileinstructions, placement: taking into the account sensors the can diversity be easily of placedmaterials, on current any playground condition, surface element finishes, without instructions,dimensions, taking and positions. into account the diversity of materials, current condition, surface finishes, 2. dimensions,Intuitive single and positions.solution grip: HybridPLAY is mainly for kids, so it requires an intuitive grip, allowing children to easily change the game whenever they want with minimal installation time. 2. Intuitive single solution grip: HybridPLAY is mainly for kids, so it requires an intuitive grip, 3. Customizable and suitable for all ages: though initially intended for children, HybridPLAY is allowing children to easily change the game whenever they want with minimal installation time. versatile and has an immense range of potential users. 3. 4. CustomizableCompact and andweather suitable-resistant: for all n ages:aturality though and impulsiveness initially intended are key for in children, our games, HybridPLAY so there’s is versatileno time andfor accessories. has an immense range of potential users. 4. 5. CompactSimple Design and weather-resistant: from a single mo naturalityuld: a simple and impulsivenessdesign lets us keep are key costs in ourdown, games, and makes so there’s the no timeproject for accessories.viable. 5. Simple Design from a single mould: a simple design lets us keep costs down, and makes the project viable.

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FollowingFollowing these these five five points, points, since since its its first first release release in in 2007, 2007, the the sensor sensor has has undergone undergone some some Following these ﬁve points, since its ﬁrst release in 2007, the sensor has undergone some improvements,improvements, leading leading to to differen different versionst versions (Figure (Figure 2). 2). In In the the same same way, way, the the video video games games have have also also improvements, leading to different versions (Figure2). In the same way, the video games have evolved,evolved, based based on on the the valuable valuable feedback feedback of of targeted targeted users users (see (see Section Section 4). 4). A Abrief brief description description of of the the also evolved, based on the valuable feedback of targeted users (see Section4). A brief description of differentdifferent versions versions is isshown shown in in the the following following sub sub-sections.-sections. the different versions is shown in the following sub-sections.

Figure 2. The HybridPLAY sensor. From left to right, the ﬁrst, second and third versions. FigureFigure 2. 2.The The HybridPLAY HybridPLAY se nsor.sensor. From From left left to toright, right, the the first, first, second second and and third third version versions. s.

2.1. First Version 2.1.2.1. First First Version Version TheTheThe first ﬁrst first version version version of of of the the the HybridPLAY HybridPLAY HybridPLAY sensor sensor sensor (released (released (released in in in 2007) 2007) 2007) basically basically basically consisted consisted consisted of of of an an an Arduino Arduino Arduino miniminimini board board board [28] [ 28[28]],, a a, threea three-axis three-axis-axis accelerometer accelerometer accelerometer and and and an an an XBee XBee XBee module module module for for for the the the wirele wireless wirelessss communication communication communication [29] [ 29[29].]. . InInIn this this this first ﬁrst first version, version, version, four four four different different different models models models of of of the the the sensor sensor sensor were were were produced produced produced according according according to to to different different different elements elements elements ofofof the the the playground: playground: playground: the the swing,swing, swing, thethe the slide,slide, slide, the the the seesaw seesaw seesaw and and and the the hobbyhorse.the hobbyhorse. hobbyhorse. In In all In all of all them,of of them, them, the the housing the housing housing was wascomposedwas composed composed of a plasticof of a a plastic rectangular plastic re rectangularctangular box (see box box Figure (see (see 2Figure), Figure which 2), was 2), which which afterwards was was afterwards covered afterwards with c overed covered cardboard with with cardboard(Figurecardboard3a) (Figure and (Figure stuck 3 a)3 a)toand and the st elementsuckstuck to to the the of elementsthe elements playground of of the the playground withplayground an adhesive wi withth an Velcroan adhesive adhesive strip V (Figure elcroVelcro strip3 b).strip (FigureFor(Figure the 3 wirelessb). 3b). For For the connectivitythe wireless wireless connectivity connectivity we use the we XBeewe use use protocolthe the XBee XBee toprotocol createprotocol ato meshto create create of a sensorsmesha mesh of thatofsensors sensors send that thethat sendinformationsend the the information information to a Linux to to a laptop Linuxa Linux providedlaptop laptop provided provided with an with external with an an external XBeeexternal antenna. XBee XBee antenna. antenna. The laptop The The laptop acts laptop as acts a acts server as as a a serverwithserver a with custom-made with a acustom custom- Pythonmade-made Python serverPython server software server software software that analyzes that that analyzes analyzes the info the ofthe info the info sensors,of of the the sensors, savesensors, the save players’save the the players’scoresplayers’ and scores scores forwards and and forward theforward sensors thes the triggers sensor sensor triggers via triggers WiFi via to via theW WiFi player.iFi to to the the player. player.

(a)( a) (b()b )

FigureFigureFigure 3. 3. 3.First FirstFirst version version version of of of the the the sensor sensor. sensor. (.a ()a ( a) T) Thehe The different different different models, models, models, according according according to to to the the the elements elements elements of of of the the the playground;playground;playground; ( (bb ())b one one) one of of ofthe the the sensors sensors sensors attached attached attached to to tothe the the hobbyhorse. hobbyhorse. hobbyhorse.

TheThe first first video video games games were were designed designed by by Clara Clara Boj, Boj, and and programm programmeded by by Diego Diego Díaz Díaz and and Martín Martín The first video games were designed by Clara Boj, and programmed by Diego Díaz and Martín NadalNadal with with pygame pygame [30] [30]——a Pythona Python game game library library——andand run run on on a Nokiaa Nokia N850 N850 PDA PDA with with the the Maemo Maemo Nadal with pygame [30]—a Python game library—and run on a Nokia N850 PDA with the Maemo LinuxLinux-based-based operating operating system, system, and and produced produced by by Intermediae Intermediae Matader Matadero Madrido Madrid (Madrid, (Madrid, Spain Spain). The). The Linux-based operating system, and produced by Intermediae Matadero Madrid (Madrid, Spain). imageimage in in Figure Figure 4 a4 ashows shows our our first first video video game game called called Puzzle Puzzle City, City, which which consists consists of of a aset set of of mini mini The image in Figure4a shows our first video game called Puzzle City, which consists of a set of gamesgames where where the the character character has has to to collect collect the the pieces pieces of of a puzzlea puzzle to to collect collect points points and and fill fill a gapa gap created created mini games where the character has to collect the pieces of a puzzle to collect points and fill a gap inin the the (virtual) (virtual) city. city. When When players players fill fill this this gap, gap, they they discover discover that that the the virtual virtual world world represents represents a a created in the (virtual) city. When players fill this gap, they discover that the virtual world represents a playground.playground. Each Each mini mini game game is ismade made up up of of simple simple dynamics dynamics associated associated with with the the movement movement of of the the

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Sensors 2016, 16, 586 5 of 20 playground. Each mini game is made up of simple dynamics associated with the movement of the childchild in in the the park, park, for for example example (Figure (Figure4a) 4a) the the character character has has to to jump jump between between (virtual) (virtual) clouds clouds by by sliding sliding downdown a (real)a (real) slide, slide, where where some some clouds clouds contain contain pieces pieces of o thef the puzzle puzzle and and others other none.s none. TheThe mobile mobile device device running running the the video video game game was was wearable, wearable, as as it it was was integrated integrated of of a self-designeda self-designed braceletbracelet (Figure (Figure4b). 4b). The The system system worked worked with with four four teams teams simultaneously, simultaneously, each each one one with with a differenta different braceletbracelet color: color: blue, blue, orange, orange, red red and and green. green.

(a) (b)

FigureFigure 4. 4.Video Video game game example: example (:a ()a screenshot) screenshot of of the the game game Puzzle Puzzle City; City; and and (b ()b bracelet) bracelet to to hold hold a a mobilemobile device. device.

2.2. Second Version 2.2. Second Version The second version of the HybridPLAY sensor (released in 2009) was designed by Miguel de las The second version of the HybridPLAY sensor (released in 2009) was designed by Miguel de las Heras (Hangar, Barcelona, Spain), and was based on the technical specifications of the first version, Heras (Hangar, Barcelona, Spain), and was based on the technical specifications of the first version, to to which some improvements were added. In particular, all the electronic elements were integrated which some improvements were added. In particular, all the electronic elements were integrated into a into a single electronic board and some components were replaced. The main components of the single electronic board and some components were replaced. The main components of the HybridPLAY HybridPLAY sensor in this version are: an ATmega168 processor (compatible with Arduino), a mini- sensor in this version are: an ATmega168 processor (compatible with Arduino), a mini-USB connector, USB connector, a three-axis accelerometer, an XBee component, a sound component and RFID reader a three-axis accelerometer, an XBee component, a sound component and RFID reader and antenna. and antenna. These improvements allowed us to reduce the dimensions of the sensors and the These improvements allowed us to reduce the dimensions of the sensors and the packing box, which packing box, which also consisted of a rectangular plastic box that was stuck to the elements of the also consisted of a rectangular plastic box that was stuck to the elements of the playground with playground with Velcro. The video game (Puzzle City) was improved according of the feedback of Velcro. The video game (Puzzle City) was improved according of the feedback of kids. For example, kids. For example, we introduced the multiplayer option, where four teams can play the same game we introduced the multiplayer option, where four teams can play the same game together and the together and the laptop, that acts as a server, shows the score of each team, which is identified with laptop, that acts as a server, shows the score of each team, which is identified with a different color a different color (blue, orange, red or green) according to the bracelet worn (Figure 5). Each team was (blue, orange, red or green) according to the bracelet worn (Figure5). Each team was composed of five composed of five members, one of them acting as coordinator, who carried the PDA on a bracelet in members, one of them acting as coordinator, who carried the PDA on a bracelet in such a way that such a way that he/she could see the screen at all times to provide precise instructions to the other he/she could see the screen at all times to provide precise instructions to the other four team members. four team members. These members were running through the park by driving the physical elements These members were running through the park by driving the physical elements in order to control in order to control the video games. As the implemented video game is made up of various mini the video games. As the implemented video game is made up of various mini games, the role of the games, the role of the coordinator was swapped among players for each mini game. We also designed coordinator was swapped among players for each mini game. We also designed new games based new games based on kids’ ideas, improved the game speed and cleaned up some computational on kids’ ideas, improved the game speed and cleaned up some computational errors detected in the errors detected in the first version. first version.

(a) (b) (c)

Figure 5. Kids looking the score in the server screen (a–c). Details of the bracelet with the integrated RFID tag (b).

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child in the park, for example (Figure 4a) the character has to jump between (virtual) clouds by sliding down a (real) slide, where some clouds contain pieces of the puzzle and others none. The mobile device running the video game was wearable, as it was integrated of a self-designed bracelet (Figure 4b). The system worked with four teams simultaneously, each one with a different bracelet color: blue, orange, red and green.

(a) (b)

Figure 4. Video game example: (a) screenshot of the game Puzzle City; and (b) bracelet to hold a mobile device.

2.2. Second Version The second version of the HybridPLAY sensor (released in 2009) was designed by Miguel de las Heras (Hangar, Barcelona, Spain), and was based on the technical specifications of the first version, to which some improvements were added. In particular, all the electronic elements were integrated into a single electronic board and some components were replaced. The main components of the HybridPLAY sensor in this version are: an ATmega168 processor (compatible with Arduino), a mini- USB connector, a three-axis accelerometer, an XBee component, a sound component and RFID reader and antenna. These improvements allowed us to reduce the dimensions of the sensors and the packing box, which also consisted of a rectangular plastic box that was stuck to the elements of the playground with Velcro. The video game (Puzzle City) was improved according of the feedback of kids. For example, we introduced the multiplayer option, where four teams can play the same game together and the laptop, that acts as a server, shows the score of each team, which is identified with a different color (blue, orange, red or green) according to the bracelet worn (Figure 5). Each team was composed of five members, one of them acting as coordinator, who carried the PDA on a bracelet in such a way that he/she could see the screen at all times to provide precise instructions to the other four team members. These members were running through the park by driving the physical elements in order to control the video games. As the implemented video game is made up of various mini games, the role of the coordinator was swapped among players for each mini game. We also designed Sensorsnew2016 games, 16, 586based on kids’ ideas, improved the game speed and cleaned up some computational6 of 21 errors detected in the first version.

(a) (b) (c)

Figure 5. Kids looking the score in the server screen (a–c). Details of the bracelet with the integrated Figure 5. Kids looking the score in the server screen (a–c). Details of the bracelet with the integrated RFID tag (b). RFID tag (b). Sensors 2016, 16, 586 6 of 20

2.3. Third Version The current version of the HybridPLAY is the third versionversion (released in 2015) [[31]31].. In this case, thethe electronicselectronics ofof thethe sensorsensor were also designed by Miguel de las Heras (Hangar (Hangar,, Barcelona,Barcelona, Spain),Spain), and consistedconsisted onon the optimization ofof the components from thethe second version. The main components of the HybridPLAY sensorsensor are,are, inin thisthis versionversion (Figure6 6):): anan ATmega32U4-AUATmega32U4-AU processor processor (compatible (compatible withwith Arduino), Arduino), a USB a USB micro micro connector, connector, a three-axis a three accelerometer-axis accelerometer and gyroscope, and gyroscope, an infrared an proximity infrared sensor,proximity a LED sensor, button a LED and abutton sound and component. a sound Incomponent. this case, the In connectivitythis case, the is connectivity achieved with is Bluetoothachieved LEwith (4.1). Bluetooth LE (4.1).

Figure 6. TechnicalTechnical components of the third version of HybridPLAY.

The sensor case was designed by Joan Rojeski’s design studio with due consideration of the way childrenThe sensorinteracted case with was the designed different by Joanelements Rojeski’s of the design playground. studio withEvery due decision consideration was supported of the way by childrenprototypes interacted adapted with to the different strength elements and dimensions of the playground. of both children Every decision and adults was. supported After several by prototypesiterations and adapted size adjustments to the strength of the and clip dimensions system, a ofbalanced both children solution and was adults. found, After as shown several in iterations Figure 7. and size adjustments of the clip system, a balanced solution was found, as shown in Figure7.

(a) (b)

Figure 7. Image of the design process and different prototypes (a) and the final design (b).

Regarding video games, our primary goal for this third version was both to improve the previously developed games (art, design, coding) as well as designing new games for the platform. The games for the third version were developed for both smartphone and tablet devices, and for both Android and iOS platforms, and initially we used the game engines cocos2dx and Unity. In this version the device and the sensors are connected directly via Bluetooth LE, so there is no further need to use the laptop server and the XBee protocol. The app was designed by Clara Boj and Diego Díaz,

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2.3. Third Version The current version of the HybridPLAY is the third version (released in 2015) [31]. In this case, the electronics of the sensor were also designed by Miguel de las Heras (Hangar, Barcelona, Spain), and consisted on the optimization of the components from the second version. The main components of the HybridPLAY sensor are, in this version (Figure 6): an ATmega32U4-AU processor (compatible with Arduino), a USB micro connector, a three-axis accelerometer and gyroscope, an infrared proximity sensor, a LED button and a sound component. In this case, the connectivity is achieved with Bluetooth LE (4.1).

Figure 6. Technical components of the third version of HybridPLAY.

The sensor case was designed by Joan Rojeski’s design studio with due consideration of the way children interacted with the different elements of the playground. Every decision was supported by Sensorsprototypes2016, 16 , adapted 586 to the strength and dimensions of both children and adults. After several7 of 21 iterations and size adjustments of the clip system, a balanced solution was found, as shown in Figure 7.

(a) (b)

FigureFigure 7.7.Image Image ofof thethe designdesign processprocess and and different different prototypes prototypes ( a(a)) and and the the ﬁnal final design design ( b(b).).

Regarding video games, our primary goal for this third version was both to improve the Regarding video games, our primary goal for this third version was both to improve the previously previously developed games (art, design, coding) as well as designing new games for the platform. developed games (art, design, coding) as well as designing new games for the platform. The games The games for the third version were developed for both smartphone and tablet devices, and for both for the third version were developed for both smartphone and tablet devices, and for both Android Android and iOS platforms, and initially we used the game engines cocos2dx and Unity. In this and iOS platforms, and initially we used the game engines cocos2dx and Unity. In this version the version the device and the sensors are connected directly via Bluetooth LE, so there is no further need device and the sensors are connected directly via Bluetooth LE, so there is no further need to use Sensorsto 2016 use, 16 the, 586 laptop server and the XBee protocol. The app was designed by Clara Boj and Diego7 of 20 Díaz, the laptop server and the XBee protocol. The app was designed by Clara Boj and Diego Díaz, and andprogrammed programmed by by Emanuel Emanuel Mazza Mazza and and Diego Diego Díaz. Díaz. This This app app includes includes different different video video games games like like Space SpaceKids Kids or or Puzzle Puzzle City City 2. In2. In Space Space Kids Kids (Figure (Figure8a), 8a) children, children can can clean clean the the galaxy galaxy by collectingby collecting space spacedebris, debris, explore explore a space a space station station by balancing by balanc oning the on seesaw, the seesaw, or experience or experience zero gravity zero gravity by playing by on playingthe swings.on the swings. In Puzzle In City Puzzle 2 (Figure City 82b) (Figure children 8b) aim children to ﬁnd aim puzzle to find pieces puzzle to discover pieces whatto discover is missing whatin is the missing city by in exploring the city by the exploring neighborhood the neighborhood with his/her with team, his/her walking team, around, walking and around, learning and what learndifferenting what city different spaces city are spaces meant for.are meant The app for. also The reinvents app also classicreinvents video classic games video such games as Pac-Man such as and Pac-Pong.Man and Kids Pong. are aimed Kids are to playaimed Pong to play on the Pong swing, on the or helpswing, Pac-Man or help to Pac escape-Man movingto escape their moving body on theirthe body seesaw. on the seesaw.

(a) (b)

FigureFigure 8. (a) 8. Space(a) Space Kids Kids and and(b) Puzzle (b) Puzzle City City2. 2.

The physical movements of the elements of the park, triggered by children, and their The physical movements of the elements of the park, triggered by children, and their representation in video games, have a direct correlation to facilitate and optimize the dynamics of the representation in video games, have a direct correlation to facilitate and optimize the dynamics game, with the aim that these dynamics based on movements become more intuitive, respecting and of the game, with the aim that these dynamics based on movements become more intuitive, respecting helping children to develop their spatial logic. and helping children to develop their spatial logic. For instance, when a child tilts the see-saw to the right, the character in the game moves to Table 1. Technical specifications and other characteristics for the different versions of the system. the right, and when he tilts it forward, the character moves up, etc. In the case of the slide, the character jumps when theFirst child Version slides. In theSecond case Version of swing, the characterThird moves Version synchronized with its Voltage 5 V 5 V 3.3 V movements, drawing a circumference arc. Therefore, on the one hand, the actions that the child has 6 AA 25,000 mA 2000 mAh polymer lithium 1000 mAh polymer lithium Batteries 1.2 V (x9 batteries) rechargeable battery rechargeable battery Accelerometer 3 axis ± 2 g 3 axis ± 3g 3 axis ± 16 g Gyroscope - - ±2000 °/sec (dps) Infrared proximity sensor 10–80 cm 4–40 cm 3–40 cm (optional) 125 kHz read frequency 13.56 MHz read frequency. RFID - EM4001 64-bit RFID tag MFC and PCD mode for compatible ISO/IEC14443-3 Type B and ISO/IEC14443-4 Type B cards Wireless protocol XBee/WiFi XBee/WiFi Bluetooth 4.1 LE Full duplex communication no no yes Frame rate 10 fps 15 fps 30 fps Delay (approx.) 2000 ms 1500 ms 100 ms Game programming language pygame pygame cocos2dx/Unity Requires server yes yes no Supported handheld devices Nokia N850 Nokia N850 Android and IOs SmartPhone Waterproof no no IP55 Impact resistant no no yes Adaptable to all elements in no (four different yes yes the playground designs) Ergonomic case design no no yes Sound no yes (only the sensor) yes (sensor and videogames) Complexity of animations low medium high Space Kids, Puzzle City 2, Pac- Video games Puzzle City Puzzle City (improved) Man, Pong, Moskis, HybridEDU

Sensors 2016, 16, 586 8 of 21 to perform in the playground are the same or very similar to those that he would do to play without electrical devices and, on the other hand, the physical actions have a logical and intuitive correlation in the video game. In Table1, a summary of the technical speciﬁcations for the three versions of the sensor is listed. As it can be seen, each version improves the capabilities of the former.

Table 1. Technical speciﬁcations and other characteristics for the different versions of the system.

First Version Second Version Third Version Voltage 5 V 5 V 3.3 V 6 AA 25,000 mA 1.2 V (x9 2000 mAh polymer lithium 1000 mAh polymer lithium Batteries batteries) rechargeable battery rechargeable battery Accelerometer 3 axis ˘ 2 g 3 axis ˘ 3g 3 axis ˘ 16 g Gyroscope - - ˘2000 ˝/sec (dps) Infrared proximity sensor 10–80 cm 4–40 cm 3–40 cm (optional) 125 kHz read frequency 13.56 MHz read frequency. RFID - EM4001 64-bit RFID tag MFC and PCD mode for compatible ISO/IEC14443-3 Type B and ISO/IEC14443-4 Type B cards Wireless protocol XBee/WiFi XBee/WiFi Bluetooth 4.1 LE Full duplex communication no no yes Frame rate 10 fps 15 fps 30 fps Delay (approx.) 2000 ms 1500 ms 100 ms Game programming language pygame pygame cocos2dx/Unity Requires server yes yes no Supported handheld devices Nokia N850 Nokia N850 Android and IOs SmartPhone Waterproof no no IP55 Impact resistant no no yes Adaptable to all elements in no (four different designs) yes yes the playground Ergonomic case design no no yes Sound no yes (only the sensor) yes (sensor and videogames) Complexity of animations low medium high Space Kids, Puzzle City 2, Pac-Man, Video games Puzzle City Puzzle City (improved) Pong, Moskis, HybridEDU

3. Interface Design In the following sub-sections, the technical speciﬁcations of the interface design regarding Bluetooth communication, frame rate, sensoring and user interaction are described in detail for the current version of the system—the third version. Within this, we aim at providing detailed information of the input/output parameters of the sensors and how the interaction is produced according to the different elements of the park.

3.1. Bluetooth Communication In order to communicate the sensor with the mobile devices, the Bluetooth Low Energy (BLE) or Bluetooth Smart protocols are used, both belonging to Bluetooth 4.0. The chip used is the RN4020, which is internally programmed to accommodate a private GATT service with three characteristics: NOTIFY (11 bytes), WRITE (2 bytes) and WRITE (2 bytes). In the characteristic NOTIFY, a string is recorded in hexadecimal form, which contains the following values from the sensors: IR (1 byte), BATTERY (1 byte), TILT (1 byte) and QUATERNIONS (8 bytes), where IR stands for the infrared proximity sensor. All of these values are normalized in integer values. In the case of IR and BATTERY, the values go from 0 to 100; TILT is a Boolean, so it can be 0 or 1; and QUATERNIONS go from 0 to 255. The primary difference with a standard communication through the serial port (used for example in the classic Bluetooth 2.0) is that, in the case of using private services and features, there is already a Sensors 2016, 16, 586 9 of 21

“container” prepared for the variable, which is directly accessible. By contrast, with a standard reading of the serial port, the data must be packaged and temporized to avoid overﬂow. For instance, it is common in a standard script to add a header to the message and to add a control on the reception in order to start reading only after receiving the header; this can lead to eventual jumps in reading because, if mistakenly the header is not automatically read, the rest of the message is lost until the next refresh. With the private services of the BLE, this problem disappears.

3.2. Frame Rate Regarding the electronics, the ﬁrmware internal clock is set to 25 Hz, which corresponds to 25 refreshes per second or a single refresh every 40 ms. The refresh rate is the same for all sensors. Regarding the application, a new reading of the values recorded in the feature NOTIFY (which records all sensor data) is performed at each update cycle.

3.3. Sensoring To retrieve the rotations of the sensor, the quaternion system was used, which is represented by the parameters q0, q1, q2, q3. Though less intuitive than Euler angles, quaternions provide an alternative measurement technique that does not suffer from gimbal lock, which arise when two of the three axes are aligned and a degree of freedom is lost. The relationship between quaternions and the Euler angles φ (roll), θ (pitch) and ψ (yaw) can be deﬁned as follows:

2 pq q ` q q q arctan 0 1 2 3 φ 1 ´ 2 q2 ` q2 » 1 2 fi θ “ arcsin p2 pq q ´ q q qq (1) » fi 0 `2 3 1˘ ψ — 2 pq q ` q q q ffi — arctan 0 3 1 2 ffi — ffi — 2 2 ffi – fl — 1 ´ 2 q2 ` q3 ffi – fl where the resulting angular values are between ´180˝ and` +180˘ for φ and ψ, and between ´90 and +90 for θ. The TILT parameter is internally detected by the firmware after a calibration (some consecutive lectures of the accelerometer) when the sensor is initialized. This calibration value is continuously compared with the data of the gyroscope and the accelerometer to detect if they go outside a defined range, in which case a sudden movement is detected. The accuracy of the TILT depends both on the sensor and on the defined tolerance level. The infrared proximity sensor that is currently being used, the GP2Y0E02B, has a detection range between 3 and 100 cm. Beyond this range, the sensor is set to inactive.

3.4. User Interaction

3.4.1. Springy Elements When attaching the sensor on any element of the playground that is provided with one or more springs (e.g., seesaw or hobbyhorse), the behavior of the sensor is similar to the traditional joysticks. Initially, a simple but effective calibration process is carried out (Figure9). First, the sensor is coupled in any of the orientations indicated in the app, and the user selects in the app the chosen position. Sensors 2016, 16, 586 9 of 20

2(푞0푞1 + 푞2푞3) 푎푟푐푡푎푛 2 2 ϕ 1 − 2(푞1 + 푞2 ) [θ] = 푎푟푐푠푖푛(2(푞0푞2 − 푞3푞1)) (1) ψ 2(푞0푞3 + 푞1푞2) 푎푟푐푡푎푛 2 2 [ 1 − 2(푞2 + 푞3 ) ] where the resulting angular values are between −180° and +180 for ϕ and ψ, and between −90 and +90 for θ. The TILT parameter is internally detected by the firmware after a calibration (some consecutive lectures of the accelerometer) when the sensor is initialized. This calibration value is continuously compared with the data of the gyroscope and the accelerometer to detect if they go outside a defined range, in which case a sudden movement is detected. The accuracy of the TILT depends both on the sensor and on the defined tolerance level. The infrared proximity sensor that is currently being used, the GP2Y0E02B, has a detection range between 3 and 100 cm. Beyond this range, the sensor is set to inactive.

3.4. User Interaction

3.4.1. Springy Elements When attaching the sensor on any element of the playground that is provided with one or more springs (e.g., seesaw or hobbyhorse), the behavior of the sensor is similar to the traditional joysticks. SensorsInitially,2016 a, 16simple, 586 but effective calibration process is carried out (Figure 9). First, the sensor is coupled10 of 21 in any of the orientations indicated in the app, and the user selects in the app the chosen position.

Figure 9. InstructionsInstructions to to perform perform the the calibration calibration of of the the sensor sensor with with regards regards to the to the element element of the of theplayground. playground.

Once this configurationconfiguration is finished,finished, when starting the game, the system automatically calibrates the sensor sensor with with respect respect to to the the inclination inclination it has. it has. For a For proper a proper calibration, calibration, it is necessary it is necessary that the thatelement the ofelement the park of the is as park still is as as possible. still as possible. Thanks to its sensor, twotwo generalgeneral typestypes ofof motionmotion cancan bebe detected:detected: tilt and inclination. With the tilt, sudden movementsmovements areare detected,detected, andand thethe seesaw/hobbyhorseseesaw/hobbyhorse game dynamics associated with it are established, such as increasing energy or the value of a variable of the player. For example, in thethe case of Moskis, the fly begins its flight when tilting the element of the park (Figure 10). caseSensors of 2016 Moskis,, 16, 586 the fly begins its flight when tilting the element of the park (Figure 10). 10 of 20

Figure 10. Screenshot of the video game Moskis. Figure 10. Screenshot of the video game Moskis.

The 4-way movement is more complex, and is detected when there is a significant variation in ϕ (tiltThe left– 4-wayright) movementand θ (tilt forward is more–back) complex, with andrespect is detected to the values when recorded there is in a the signiﬁcant initial calibration. variation inTheseφ (tilt movements left–right) are and usedθ (tilt in video forward–back) games to with control respect the direction to the values of the recorded user, often in onthe a initial two- calibration.dimensional Theseplane in movements an aerial view, are used such inas videoin the gamesmazes toof the control adaptio then direction of the classic of the arcade user, video often ongame a two-dimensional Pac Man (Figure plane 11). in an aerial view, such as in the mazes of the adaption of the classic arcade video game Pac Man (Figure 11).

Figure 11. Screenshot of the adaptation of the classic arcade video game Pac Man.

The effect of the inclination in the game can be digital (activating a predefined movement speed) or analog, so that the speed of the associated action is related to the value of the inclination angle.

3.4.2. The Swing In the case of the swing, the sensor must be coupled to the base thereof facing the floor, so that it can be detected. When the child sways, the sensor recognizes everytime that the swing is closer to the ground (Figure 12). In this way, the swinging speed can be calculated, since the cutting period is higher or lower depending on it.

Sensors 2016, 16, 586 10 of 20

Figure 10. Screenshot of the video game Moskis.

The 4-way movement is more complex, and is detected when there is a significant variation in ϕ (tilt left–right) and θ (tilt forward–back) with respect to the values recorded in the initial calibration. These movements are used in video games to control the direction of the user, often on a two- Sensorsdimensional2016, 16, plane 586 in an aerial view, such as in the mazes of the adaption of the classic arcade 11video of 21 game Pac Man (Figure 11).

Figure 11. Screenshot of the adaptation of the classic arcade video game Pac Man. Figure 11. Screenshot of the adaptation of the classic arcade video game Pac Man.

The effect of the inclination in the game can be digital (activating a predefined movement speed) or analog,The effect so that of thethe inclinationspeed of the in associated the game canaction be digitalis related (activating to the value a predeﬁned of the inclination movement angle. speed) or analog, so that the speed of the associated action is related to the value of the inclination angle. 3.4.2. The Swing 3.4.2. The Swing In the case of the swing, the sensor must be coupled to the base thereof facing the floor, so that In the case of the swing, the sensor must be coupled to the base thereof facing the ﬂoor, so that it it can be detected. When the child sways, the sensor recognizes everytime that the swing is closer to can be detected. When the child sways, the sensor recognizes everytime that the swing is closer to the ground (Figure 12). In this way, the swinging speed can be calculated, since the cutting period is the ground (Figure 12). In this way, the swinging speed can be calculated, since the cutting period is higher or lower depending on it. higherSensors 2016 or lower, 16, 586 depending on it. 11 of 20

Figure 12.12. Instructions on how to trigger interaction with the swing.

These movements can be reflected reﬂected in the actions of the app in different ways, for example to control thethe speedspeed of of the the protagonist protagonist or or to alsoto also control control its position, its position, moving moving from from left to left right to ofright the screen,of the inscreen, a linear in motion, a linear or motion, forming or an forming arc. An an example arc. An is depicted example in is Figuredepicted 13, wherein Figure the movements13, where the of themovements swing produce of the swing an interaction produce in an the interaction video game in HybridEDUthe video game (in thisHybridEDU example, (in intended this example, to play aintended piano). to play a piano).

Figure 13. Example of the interaction produced in the game HybridEDU with the swing.

3.4.3. The Slide In this case the sensor must be attached to the side of the slide, so that the infrared proximity sensor is facing the child, sensing his presence when sitting at the top of the slide. To ensure that the child is waiting to pounce, the app detects whether the infrared proximity sensor has been cut for at least 2 s. Once the presence of the child has been detected, a signal appears in the game indicating that the system is ready to detect his jumping (Figure 14).

Figure 14. Schematic of the interaction produced by placing the sensor on the slide. The system detects that the child is waiting for jumping.

Sensors 2016, 16, 586 11 of 20 Sensors 2016, 16, 586 11 of 20

Figure 12. Instructions on how to trigger interaction with the swing. Figure 12. Instructions on how to trigger interaction with the swing. These movements can be reflected in the actions of the app in different ways, for example to These movements can be reflected in the actions of the app in different ways, for example to control the speed of the protagonist or to also control its position, moving from left to right of the control the speed of the protagonist or to also control its position, moving from left to right of the screen, in a linear motion, or forming an arc. An example is depicted in Figure 13, where the screen, in a linear motion, or forming an arc. An example is depicted in Figure 13, where the movements of the swing produce an interaction in the video game HybridEDU (in this example, Sensorsmovements2016, 16 ,of 586 the swing produce an interaction in the video game HybridEDU (in this example,12 of 21 intended to play a piano). intended to play a piano).

Figure 13. Example of the interaction produced in the game HybridEDU with the swing. FigureFigure 13.13. ExampleExample ofof thethe interactioninteraction producedproduced inin thethe gamegame HybridEDUHybridEDU withwith thethe swing.swing. 3.4.3. The Slide 3.4.3.3.4.3. TheThe SlideSlide In this case the sensor must be attached to the side of the slide, so that the infrared proximity InIn thisthis casecase thethe sensorsensor mustmust bebe attachedattached toto thethe sideside ofof thethe slide,slide, soso thatthat thethe infraredinfrared proximityproximity sensor is facing the child, sensing his presence when sitting at the top of the slide. To ensure that the sensorsensor isis facingfacing thethe child,child, sensingsensing hishis presencepresence whenwhen sittingsitting atat thethe toptop ofof thethe slide.slide. ToTo ensureensure thatthat thethe child is waiting to pounce, the app detects whether the infrared proximity sensor has been cut for at childchild isis waitingwaiting toto pounce,pounce, thethe appapp detectsdetects whetherwhether thethe infraredinfrared proximityproximity sensorsensor hashas beenbeen cutcut forfor atat least 2 s. Once the presence of the child has been detected, a signal appears in the game indicating leastleast 22 s.s. Once Once the the presence presence of of the the child child has has been been detected, detected, a signal a signal appears appears in the in gamethe game indicating indicating that that the system is ready to detect his jumping (Figure 14). thethat system the system is ready is ready to detect to detect his jumping his jumping (Figure (Figure 14). 14).

Figure 14. Schematic of the interaction produced by placing the sensor on the slide. The system detects Figure 14. Schematic of the interaction produced by placing the sensor on the slide. The system detects Figurethat the 14. childSchematic is waiting of the for interaction jumping. produced by placing the sensor on the slide. The system detects thatthat thethe childchild isis waitingwaiting forfor jumping.jumping.

Regarding to the child jumping to the slide, it is only detected the instant when it occurs, but not the speed or time sliding down the slide. Other actions may be associated with the activation of any event, such as a shot or the game's protagonist jump.

3.4.4. Other Possibilities of User Interaction The games designed for HybridPLAY can also use the classical mechanisms of interaction provided on smartphones, such as the interaction with the screen through the touch (single touch or multi touch) or the internal accelerometers. The actions associated with these interactions are the same as in other video games for mobile devices, but are of particular interest and relevance as they complement those of the HybridPLAY device, as the child with the role of coordinator has to order the actions to be taken, at the same time that he/she interacts with the game.

4. Evaluation and Discussion Since its beginnings in 2007, the HybridPLAY system has been tested and exhibit in many different places, from artistic exhibitions to conferences and workshops. Altogether, the HybridPLAY system has been tested by around 1500 children and 400 parents (estimated values). Based on the feedback of these trials, the sensor has evolved from its ﬁrst to the current version. The complete list where Sensors 2016, 16, 586 13 of 21

HybridPLAY has been tested/exhibited up to date is provided in the following points, according to its different versions. The approximate number of people (children and adults) that tested the system is also given. The ﬁrst version was exhibited and/or tested in:

‚ Utopias, artistic residence, Intermediae Matadero (Madrid, Spain, 2007)—30 children, 10 adults ‚ A new economy, Ars Electrónica Festival (Linz, Austria, 2008)—40 children, 20 adults ‚ Amber 08 Festival (Istanbul, Turkey, 2008)—50 children, 10 adults ‚ Hybrid Playground, Techformance Festival (Murcia, Spain, 2009)—100 children, 30 adults ‚ Techformance, Arco 09, Stand Región de Murcia, (Murcia, Spain, 2009). Exhibition ‚ Hybrid Playground, LAboral Centro de Arte y Creación Industrial, (Gijón, Spain, 2009)—300 children, 60 adults

The second version was exhibited and/or tested in:

‚ Hybrid Playground, Mobilefest 09 (Sao Paulo, Brazil, 2009)—200 children, 50 adults ‚ Taller Hybrid Playground (Valdemoro, Spain, 2009)—60 children, 20 adults ‚ Hybrid Playground WIP 09, (Barcelona, Spain, 2009)—40 children, 0 adults ‚ Hybrid Playground, MuPAI, Museo Pedagógico de Arte Infantil (Madrid, Spain, 2010)—0 children, 40 adults ‚ Hybrid Playground, PAM, Cal Masó, (Tarragona, Spain, 2010)—40 children, 10 adults ‚ Hybrid Playground Hó Play 2010, Certamen internacional de videojuegos independientes, (Bilbao, Sain, 2010)—40 children, 10 adults ‚ Paisatge?, Bolit La Rambla, (Girona, Spain, 2010)—200 children, 60 adults ‚ Create your world, Ars Electrónica Festival 11 (Linz, Austria, 2011)—50 children, 20 adults ‚ Mercé Arts al Carrer (Barcelona, Spain, 2012)—200 children, 100 adults ‚ Games on public space: Hybrid Play, Conference at School of Software and Microelectronics, Beijin University, (Beijin, China, 2014).

To date, the third version has been exhibited in:

‚ Workshop in TEDx Barcelona education (Barcelona, Spain, 2015)—0 children, 30 adults ‚ Workshop Medialab-Prado (Madrid, Spain, 2015)—12 children, 25 adults ‚ Workshop La Fira d’Oci Infantil i Juvenil de Nadal, (Castellón, Spain, 2016)—100 children, 50 adults

4.1. Workshops The performed workshops with group of children have had an approximate duration of two hours each, and have been organized as indicated in Table2. The experience of the workshops was very positive. From the first moment, children were quite engaged with the proposed games, and enjoyed the system very much. However, despite the great success of the system in the first version, we found some aspects that needed to be improved, which were based on our personal observations and the feedback from parents and children. Regarding to the participation of children, we noticed that children between 6 and 10 years old responded better to the system, while children under 6 didn’t have enough strength to move the spring elements and also experienced some difficulty in understanding the dynamics of the games children over 10 tended to feel very attracted to the system, but the available games seemed too simple to them. Besides, some children under 8 had difficulty discerning between left and right, and also in being to swing on the swings without the help of another child or adult. Regarding the task of coordinator, children performed differently according to their personal profiles: while some of them felt more comfortable doing this task, others (more introverted) had a harder time at first, but soon developed well in this task. We also found no integration problems with the other children of the park that were Sensors 2016, 16, 586 14 of 21 not playing with HybridPLAY, so we can say that the system does not interfere with the normal use of the park by other children. Additionally, after finishing the workshops, many children continued playing in the park imagining they were doing that with HybridPLAY, and also brought their own ideas for games to take place, and thus we can conclude that the system encourages imagination and creativity. Also, parents were easily engaged into the dynamics of the game, and so HybridPLAY functions as an integrator of family activity at playgrounds.

Table 2. Schedule for the workshops.

Duration Description - Beginning. The group of children arrives to the playground 10 min Children freely play with the elements of the playground. Observation. Brief talk relating to the games in the playground. Some questions arise, such as: ‚ Do you usually play in the playground? ‚ What are your favourite elements of the playground? 5 min ‚ What element do you like the least? ‚ Is there any missing element which you would like to play with? Which one? ‚ Do you ﬁnd funny the see-saw, the swing, etc.? Brief talk relating to the workshop, explaining: ‚ The games proposed in HybridPLAY ‚ The role of children as avatars 5 min ‚ The responsibility of children regarding each other and the devices that they carry during the game ‚ The organization into two teams The elements of the game: the way the HybridPLAY sensors are integrated in the different 10 min elements of the playground and how do they work. Creation of gaming teams: ‚ Four groups of 3 to 4 players ‚ Two groups of observers 5 min These groups rotate, in such a way that every children becomes a player and an observer. Each group of players has a game coordinador, which is the child that holds the smartphone. For every mini game, the game responsibility changes, so all the kids will hold the smartphone and coordinate the team. The sensors are handed to the children. Game experience: Children freely play with the HybridPLAY platform integrated in the 20 min elements of the playground. Observation. The observers do not participate in the game, but only see the actions of their colleagues. 5 min Group rotation. Players become observers and vice versa. 20 min Game experience. Brief talk. Feedback from children. Some questions arise: What do you think about the game experience? Do you ﬁnd it funny? Would you like to play more complex games following this system? 15 min Was it easy to understand how it works? As an observer, what have you seen? What kind of games would you like to play at the playground? What others improvements do you suggest for the system? - End of the workshop

Besides these good results, there were other issues and technical aspects that could be improved. For instance, regarding the game dynamics, it would be interesting to compete between teams for a global gaming session in order to increase user engagement and game capabilities. Regarding the technology itself, we found that the technological system used in this first version was not very portable and lacked complete autonomy (e.g., short battery life). Regarding the proposed video games, it would be interesting to add other elements, such as animations. We were also conscious that the Sensors 2016, 16, 586 15 of 21 videogames responses were slightly slow (mainly due to the mobile technology) and that some bugs had to be corrected. All the aforementioned negative aspects were tackled in the second version of HybridPLAY. The autonomy and portability of the system was greatly improved. In this regards, we constructed a portable cart to transport all the equipment, which was equipped with a car battery and an inverter to provide power to the laptop and recharge the batteries of the sensors and PDAs. When the car was unfolded, a 24-inch flat screen showed the players the status of their game, the mini game they were playing and the points scored by each of the four teams. This display was very well received as children continually ran to the car to see the status of the game. The workshops carried out with the second version of the system also had great acceptance by children and parents. Additionally, we found that the game dynamics were more fluent due to the improvements that were made. For instance, the improvement of the battery life and the absence of inconsistence errors in the video games was deterministic. In this way, the game was not interrupted at any time, leading to a greater user engagement. Also, the addition of animations in the video games and the possibility to compete among teams was greatly accepted by both children and parents, as the gaming possibilities augmented, as well as the teamwork. However, other issues were found which motivated other modifications and improvements, leading to the third version of the system. In the third version, we included more complete and sophisticated dynamics in the videogames, as well as sound output and more attractive animations, also increasing the speed response. Regarding to the technology, the autonomy and portability of the system was further increased (allowing 20 h of continuous play), while the server computer was eliminated, and hence also the need to use the car with the car battery and the inverter. The improvements made in the third version lead to a pre-industrial system, with all the aforementioned encountered issues addressed. The feedback after the last workshop carried out to date (TEDx Barcelona) make us think that HybridPLAY has great potential in the entertainment, education and fitness markets, and that the targeted users are not restricted to children, but also e.g., parents are engaged in the game.

4.2. Exhibitions The HybridPLAY system was presented at some artistic exhibitions, attracting the curiosity of the general public. In Figure 15b the system is depicted at the Techformance Festival (Murcia, Spain, 2009). As this was version 2, the cart was used, which was designed with the purpose of augmenting the autonomy of the overall system. The cart was provided with a car battery and an inverter, that allowed us to increase the autonomy of the system from 2 to 6 h and also to recharge the PDAs. This was relevant for the exhibitions, where the system was on display for the whole day. The cart had a set of drawers covered with foam to absorb impacts and to transport tools, the Velcro, sensors, batteries, inverter, etc. It was equipped with two doors that could be extended, forming a table and, when closed, it was compact enough and highly resistant to transport all the material, so it could be easily transported to different exhibition venues. Sensors 2016, 16, 586 15 of 20

Sensorsforming2016 a, 16table, 586 and, when closed, it was compact enough and highly resistant to transport all16 ofthe 21 material, so it could be easily transported to different exhibition venues.

(a) (b)

Figure 15.15. Cart ofof HybridPLAYHybridPLAY in in the the park park ( a()a) with with the the monitor monitor showing showing the the score score of of the the games games and and at oneat one of theof the exhibitions exhibitions (b )( withb) with the the monitor monitor showing showing a loop a loop of theof the video video games. games.

4.3. Quantitative Evaluation 4.3. Quantitative Evaluation A quantitative user evaluation of the HybridPLAY system was carried out during the Workshop A quantitative user evaluation of the HybridPLAY system was carried out during the Workshop La Fira d’Oci Infantil i Juvenil de Nadal, (Castellón, Spain, 2016) with the third version of the system. La Fira d’Oci Infantil i Juvenil de Nadal, (Castellón, Spain, 2016) with the third version of the system. Around 150 people tested the system at the workshop, from which a total of 87 acceded to fill out a Around 150 people tested the system at the workshop, from which a total of 87 acceded to ﬁll out a pair pair of questionnaires, that were related to the usability of the system and the individual’s satisfaction of questionnaires, that were related to the usability of the system and the individual’s satisfaction with with the proposed activity, where the System Usability Scale (SUS) [32] was chosen to measure the proposed activity, where the System Usability Scale (SUS) [32] was chosen to measure usability. usability. The participants were both adults (32 participants) and children (55 participants). The adults The participants were both adults (32 participants) and children (55 participants). The adults that participated in the survey were the parents of children, who often took the role of coordinators. that participated in the survey were the parents of children, who often took the role of coordinators. In Table3, the socio-demographic data of these two groups is provided, showing the mean, standard In Table 3, the socio-demographic data of these two groups is provided, showing the mean, standard deviation (s.d.) and minimum and maximum age of the participants. Other parameters used are deviation (s.d.) and minimum and maximum age of the participants. Other parameters used are gender and how often they use video games, where the range 0–4 for the frequency (f.) means: 0: gender and how often they use video games, where the range 0–4 for the frequency (f.) means: 0: never or almost never; 4: every day. Most of the children participating in the questionnaires fulﬁlled never or almost never; 4: every day. Most of the children participating in the questionnaires fulfilled them with the help of their parents and/or other adults supervising the activity. As we have detected them with the help of their parents and/or other adults supervising the activity. As we have detected slightly different results in the questionnaires regarding adults and children, so we present the results slightly different results in the questionnaires regarding adults and children, so we present the results divided into these two groups. We have, however, not detected relevant differences regarding gender divided into these two groups. We have, however, not detected relevant differences regarding gender and video game use frequency. and video game use frequency. Table 3. Socio-demographic data of the participants. Table 3. Socio-demographic data of the participants.

AdultsAdults Children Children AgeAge meanmean s.d.s.d. minmin max mean mean s.d. min maxmax 35.2535.25 7.577.57 2222 47 8.56 8.56 2.05 6 1212 GeGendernder malemale femalefemale male male femalefemale 1414 1818 31 31 2424 VideogameVideogame f.f. 0 0 f.f. 1 1 f.f. 2 2 f.f. 33 f. f. 4 4 f. f. 0 0 f.f. 11 f. 2 f.f. 33 f.f. 4 4 frequencyfrequency (%)(%) 12.5012.50 40.6340.63 31.2531.25 9.38 6.25 6.25 1.82 1.82 9.09 25.45 30.9130.91 32.7332.73

The results of the SUS questionnaire are listedlisted in Table 4 4,, where where the the obtainedobtained scoresscores areare providedprovided forfor the the two two considered considered groups, groups, adults adults andand children. children. I Inn questions 1 to 10 the range 0–40–4 means:means: 0: strongly disagree, 4: strongly agree. The The values values of of the the SUS SUS score, score, however, however, range range from from 0 0 to 100, meaning 100 the best imaginable result. For the adults group, this score reaches 84.92 points; for the children group,group, the the score score is is slightly slightly better, better, reaching reaching 91.23 91.23 points. points. These These values values can becan considered be considered good (forgood adults) (for adults) and excellent and excellent (for children) (for children) on the on scale the of scale scores of scores provided provided by the by questionnaire the questionnaire and taking and intotaking account into account the fact the a minimum fact a minimum score of score 68 would of 68 bewould deemed be deemed acceptable acceptable for a tool for [ 33a tool,34]. [33,34].

Sensors 2016, 16, 586 17 of 21

Table 4. Results of SUS questionnaire (mean, standard deviation, minimum and maximum).

Adults Children Questions mean s.d. min max mean s.d. min max 1. I think that I would like to use this system frequently 3.28 0.57 2 4 3.78 0.45 2 4 2. I found the system unnecessarily complex 1.19 0.73 0 2 0.55 0.71 0 2 3. I thought the system was easy to use 3.59 0.55 2 4 3.78 0.49 2 4 4. I think that I would need the support of a technical 0.41 0.55 0 2 0.38 0.59 0 2 person to be able to use this system 5. I found the various functions in this system were well 3.22 0.48 2 4 3.82 0.39 3 4 integrated 6. I thought there was too much inconsistency in this 0.69 0.81 0 2 0.55 0.60 0 2 system 7. I would imagine that the most people would learn to 3.72 0.80 1 4 3.75 0.44 3 4 use this system very quickly 8. I found the system very cumbersome to use 0.69 0.58 0 2 0.49 0.68 0 2 9. I felt very conﬁdent using the system 3.38 0.60 2 4 3.65 0.55 2 4 10. I needed to learn a lot of things before I could get going 0.25 0.43 0 1 0.33 0.47 0 1 with this system SUS score 84.92 11.48 52.50 100.00 91.23 11.05 65.00 100.00

The results of the individuals’ satisfaction questionnaires are given in Table5 for the two considered groups. The scores also range from 0 to 4, meaning: 0: strongly disagree, 4: strongly agree. As it can be seen, results are very satisfactory. As a general observation, it can be seen that the adults is more critical, as slightly worse scores are obtained for almost all the questions of the two questionnaires. Besides, the obtained results are excellent or almost excellent, what we believe is the consequence of the different improvements carried out for the HybridPLAY system, after listening to users’ feedback during the many organized workshops and exhibitions during the last years.

Table 5. Results of the individuals’ satisfaction questionnaires (mean, standard deviation, minimum and maximum).

Adults Children Questions mean s.d. min max mean s.d. min max 1. I liked very much playing with the video games 3.69 0.46 3 4 3.84 0.37 3 4 2. I ﬁnd the video games appropriated for my age 3.44 0.66 2 4 3.82 0.39 3 4 and/or my children’s age 3. I liked very much the concept of playing with the 3.69 0.46 3 4 3.87 0.33 3 4 elements of the park inside HybridPLAY 4. I ﬁnd it very easy to collaborate with other friends 3.63 0.48 3 4 3.76 0.42 3 4 in HybridPLAY 5. I would like to play more with HybridPLAY 3.72 0.45 3 4 3.87 0.33 3 4 6. I would like to recommend others to play with 3.66 0.54 2 4 3.85 0.35 3 4 HybridPLAY

4.4. Extended Uses of HybridPLAY Although our main targeted audience are children, the HybridPLAY sensor can be also used by other users such as seniors. In Figure 16, an example is shown with the sensors placed at other elements of the playground that are intended to do exercise. In this case, the video games were adapted, in such a way that we simpliﬁed the graphics and game dynamics by using basic shapes and colors. We would like to stress the potential value of HybridPLAY to help the physical and verbal synchronization of seniors by motivating their mental activation and improving their response time to external stimuli. Sensors 2016, 16, 586 18 of 21 Sensors 2016, 16, 586 17 of 20 Sensors 2016, 16, 586 17 of 20

(a) (b) (a) (b) FFigureigure 16. SeniorsSeniors playing playing with HybridPLAY at the elliptical machine (a)) and atat thethe abab twistertwister ((bb).). Figure 16. Seniors playing with HybridPLAY at the elliptical machine (a) and at the ab twister (b). The versatile character of HybridPLAY means that it is not restricted to be outdoor use, and The versatile character of HybridPLAY means that it is not restricted to be outdoor use, and indoor indoorThe activities versatile can character also be of performed. HybridPLAY In this means regards, that it Hybrid is notPLAY restricted has to also be been outdoor tested use at, and the activities can also be performed. In this regards, HybridPLAY has also been tested at the classroom classroomindoor activities level (Figure can also 17) be and performed. extra school In thisactivities, regards, where Hybrid kidsPLAY can enjoy has also and beenlearn testedat the atsame the level (Figure 17) and extra school activities, where kids can enjoy and learn at the same time they are timeclassroom they are level playing (Figure with 17) HybridPLAY. and extra school We activities,have developed where akids set ofcan basic enjoy games and learnwith educationalat the same playing with HybridPLAY. We have developed a set of basic games with educational contents such as contentstime they such are asplaying maths, with wher HybridPLAY.e kids can learn We basic have addition developed and a multiplicationset of basic games operations. with educational So far, we maths, where kids can learn basic addition and multiplication operations. So far, we have received a havecontents received such asa very maths, positive where feedback kids can fromlearn thisbasic experience, addition and maybe multiplication due to the operations.fact that the So physical far, we very positive feedback from this experience, maybe due to the fact that the physical activity helps the activityhave received helps the a very mental positive activation feedback and fromthe subsequent this experience, learning maybe process. due to the fact that the physical mentalactivity activation helps the andmental the activation subsequent and learning the subsequent process. learning process.

Figure 17. Children and parents designing their own games for HybridPLAY at the Medialab-Prado Figure 17. Children and parents designing their own games for HybridPLAY at the Medialab-Prado Figure(Madrid, 17. Spain)Children workshop. and parents designing their own games for HybridPLAY at the Medialab-Prado (Madrid, Spain) workshop. (Madrid, Spain) workshop. The video games can be also customized, in such a way that the educational sector can benefit from The HybridPLAY, video games including can be also the customized, education of in kisuchds witha way special that the needs. educational In this sector regards can we benefit have The video games can be also customized, in such a way that the educational sector can beneﬁt from developedfrom HybridPLAY, some basic including experiences the education with kids of with kids diminished with special mental needs. capabilities In this regards and we we have HybridPLAY, including the education of kids with special needs. In this regards we have developed realizeddeveloped that some in some basic cases, experiences after properly with kidsadjusting with thediminished level of themental game, capabilities our system and can we be havevery some basic experiences with kids with diminished mental capabilities and we have realized that in positiverealized forthat their in some mental cases, development. after properly adjusting the level of the game, our system can be very positive for their mental development.

Sensors 2016, 16, 586 19 of 21 some cases, after properly adjusting the level of the game, our system can be very positive for their mental development.

5. Conclusions and Further Work In this paper we have presented HybridPLAY, a new platform composed of sensor units and video games that fosters outdoor physical activity, verbal communication and teamwork. We have described the work performed to date, both at the technological and at the evaluation (user-related issues) level, that has led us to achieve a robust version of both the sensor and the video games. The results of a quantitative evaluation of the system carried out for its third version are excellent, what we believe is a consequence of the different improvements carried out for the HybridPLAY system, after responding to users’ feedback during the many organized workshops and exhibitions attended during the last years. We also have demonstrated the versatile character of HybridPLAY. Though initially intended to foster outdoor physical activity in playgrounds, where the main targeted users are children, HybridPLAY can also be used by other audiences (e.g., seniors) and can be used indoors. Additionally, the video games can be customized in order to provide benefits in the educational sector, including the education of people with special needs. HybridPLAY is a platform that started as an artistic initiative to address actual problems, that however has today reached great acceptance by the public and has become the primary product of Lalalab Projects. With a view the mass production and commercialization of the HybridPLAY platform, some steps are still required. In particular, regarding the hardware, we intend to reduce the dimension of the sensor; regarding to the software, we intend to build a platform that allow users to design their own games. We also intend to introduce the sensor in the entertainment, education and fitness markets, possibly customizing some of the features of HybridPLAY (e.g., video games) for the different sectors. Additionally, we believe that HybridPLAY can be used as a complementary tool to fight overweight and obesity in children, as it fosters physical activity. In order to demonstrate this claim, we plan to provide a group of children with our technology for two or three months, to track their physical activity and to evaluate the use they make of it.

Acknowledgments: We would like to thank other researchers and designers who contributed to the development of HybridPLAY, which have been cited through the paper. We would also like to thank all the people that have participated in testing our system. Author Contributions: Diego José Díaz and Clara Boj conceived and designed HybridPLAY and are the owners of all images reported in the paper. Cristina Portalés contributed to analyze the state of the art, the evaluation results and wrote the paper. Conﬂicts of Interest: The authors declare no conﬂict of interest.

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