"crafti" is the Catalan acronym for "Method for the Control and Regulation of Physical Activity of Children through a Novel Platform for Full-body Interactive Experiences called the Interactive Slide".

The Interactive Slide (UPF Patent) is a large inflatable slide that is augmented with interactive technology. The current configuration has a sliding surface 4 meters wide and 3 meters long, which acts also as an image projection screen. A computer vision system detects the movements, actions and attitudes of children to allow them to play with an interactive experience on the sliding surface of the slide. Myriad games and educational experiences may be designed and developed for the surface of the slide without having to change the underlying infrastructure.

Interactive Slide

The backdrop of this project is the following:

Current developments in ICT have signified a tremendous impact on society, rooted so deeply into contemporary culture that children and youngsters have adopted them as an integral part of their lives in their daily activities. This is viewed by some (according to a number of studies by the World Health Organisation [[1][2][3][4][5]]), as one of the causes for sedentary and isolated lifestyles in children and youngsters in Europe, and thereby as limiting their physical activity and face-to-face social interaction, affecting their present and future health and development. This proposal will find ways in which interactive technology can contribute to counter these negative effects and pull children out of their sedentary lifestyles, even in those subjects that reject doing sport activity.
Current full-body real-time interaction HCI techniques can be successfully merged with traditional physical play structures. An example is our “Interactive Slide” platform which brings together the best of both worlds by offering children the possibility to keep playing with interactive media and engaging them while doing physical activity in a natural way. This will represent a huge leap forward from current videogame console strategies of combining interactive media and exercise, such as the Nintendo Wii that can allow little exercise in the home environment, whereas we will provide tools for schools, social centres, physical education institutions, etc.
For these experiences to truly become tools for public health and help counter the lack of physical activity we must provide evidence that the new technology can control and regulate the amount of physical activity that children do in it. The research steps needed to find methods and strategies to achieve this are:

  1. Analyse the type of physical activity that the Interactive Slide provides.
  2. Define the best way in which the system can detect the amount of physical activity during play.
  3. Find application parameters that correlate with the amount of physical activity to have full control over this activity.
  4. Analyse how physical activity can be modulated from the system through user tests with large quantities of groups of children.

To this end the research groups that come together in this proposal provide a perfect complementary profile as UPF has all the technological HCI knowledge and expertise, while INEFC has all the knowledge on physical activity and health analysis and management, as well as providing access to a significant number of users for the correct development of all tests.

To control and modulate the amount of physical activity of groups of children we will study the potential of a novel notion we have defined: the “Interaction Tempo”. We will apply quantitative methods to assess the effectiveness of this parameter. We will asses the impact of the Interactive Slide on the engagement of children through ethnographic studies according to the interaction design premises of collaborative teamwork experiences.
We will at all times guarantee ethical treatment of users and user anonymity as well as guaranteeing healthy levels of exertion.
This research follows from past research on Interactive Playgrounds and has a clear view into the future achievement of a tool for public health that is also fun for children.

  1. Cavill, N., Kahlmeier, S., and Racioppi, F. (Editors), Physical activity and health in Europe: evidence for action, WHO Library Cataloguing in Publication Data , World Health Organization 2006, ISBN 92 890 1387 7, www.euro.who.int/document/e89490.pdf
  2. Currie, C., Roberts, C., Morgan, A., Smith, R., Settertobulte, W., Samdal, O., and Barnekow, V. (Eds) Young people’s health incontext, WHO Library Cataloguing in Publication Data, World Health Organization (2004), ISBN 92 890 1372 9, www.euro.who.int/Document/e82923.pdf
  3. Edwards, P., and Tsouros, A. (Eds) Promoting physical activity and active living in urban environments. The role of local governments. The solid facts, WHO Library Cataloguing in Publication Data, World Health Organization (2006), ISBN 92 890 2181 0, (last accessed 09/16/08)
  4. Green, G., and Tsouros, A. (Eds) City leadership for health. Summary evaluation of Phase IV of the WHO European Healthy Cities Network, WHO Library Cataloguing in Publication Data, World Health Organization (2006), ISBN 978 92 890 4287 1, (last accessed 09/16/08)
  5. Mathieson, A., and Koller, t. (Eds) Addressing the socioeconomic determinants of healthy eating habits and physical activity levels among adolescents, WHO Library Cataloguing in Publication Data, World Health Organization (2006), ISBN 92 890 2180 2, (last accessed 09/16/08)


Balloon Game

In the Balloons Game, children must synchronize their actions to slide over virtual balloons (a) that appear from the sides of the projection area and cross during three seconds the sliding surface. If children successfully slide over a balloon they pop it and obtain a virtual object (b). These objects must be piled up at the bottom of the projection area (c) to reach a target circle on a level bar (d). From time to time, a bomb appears instead of a balloon (e). If the bomb falls to the bottom of the play area and explodes, it destroys the structure of objects that has been constructed until then and displaces the target to a new position on the bar. Children must slide over the bomb to defuse it before it falls. When the structure of virtual objects reaches the target the game moves to the next level. There are five levels, each of them with specific virtual objects. For instance, the third level has an outer space theme and the virtual objects can for example be rockets or robots. At each new level of the game the target is positioned at a higher location forcing users to pile up more objects to reach the target. Moreover, the objects of each new level are also smaller and irregular and hence they are more difficult to pile up. Overall, this game demands teamwork and promotes intense physical activity.


Fish Game

In the Fish Game, the users must collect ten fish to pass to the next level. To catch a fish, one player must slide over it (a) when it appears from behind an element in the virtual sea. When the fish is correctly hit, it jumps out of the water. Another player at the top of the slide must then catch the fish by hitting it with any part of the body (b). If timely hit, the fish is directed into the fishing boat that moves from side to side on the surface of the virtual sea (c). Catching each fish increases the players’ score (d). Once in a while, a bird appears on either side of the top of the play area. The bird flies over the ship and dives down on it to steal a fish. The players must try to scare the bird away as soon as it appears, before it dives on the ship, by intensively waving their arms over it. If they do so on time and with sufficient intensity, the bird flies away (e). The game incorporates movements related to speed, endurance, strength, balance and coupling, as recommended by the experts from INEFC. This is achieved through two main movements: arm waving and the slide-hit combination. Arm waving fosters coupling, speed and endurance since the child must do it on time and with sufficient intensity. The slide-hit combo fosters strength and balance since the children must either react quickly to the fish appearing in the virtual sea and throwing their body down the slide, or hanging down to reach the jumping fish. There is also a collaborative coupling component since they have to act in a coordinated arrangement.


Fixed Interaction Tempo

IV: Interaction Tempo (IT) (Low-Medium-High)

DV: Change in heart rate (CHR) (Ground truth value recorded with HR memory belts), Amount of Physical Activity (APA) (Measured by the a vision system)


In our first study, our goal was to validate the Interaction Tempo(IT) as a valid parameter to control the amount of physical activity(APA) measured by our vision system. This way, we have triangulated our measures to validate our following hypotheses:

H1: The change in heart rate(CHR) of the users, as our ground true value, can be significantly related to the IT set by the system.

H2: The APA as recorded by the vision system is significantly related to the IT set by the system.

H3: A significant correlation exists between the CHR of the users and the APA as measured by the vision system.

In sum, an ANOVA with bonferonni correction revealed a significant difference for the APA and CHR between each IT conditions. In addition, we have recorded a significant correlation between APA and CHR of .717.

Modulated Interaction Tempo

IV: Modulation of the Interaction Tempo (LHM-MHL-HML)

DV: Change in heart rate (CHR) (Ground truth value recorded with HR memory belts), Amount of Physical Activity (APA) (Measured by the a vision system)


In our previous study we validated the adaptation of physical activity of children throughout a play session at a fixed IT.  Hence, our following goal was to test whether children adapted their APA to changes in IT over three tempi conditions, within a single play session.

We followed the same procedural steps as in the previous study. A total 178 children ages 10 to 12 came from public and private schools all over the greater Barcelona area to participate in this study that took place during one week.

In both games the difference in the APA and CHR were globally significant between each IT. Also the correlation between APA and CHR was significant for both game with a coefficient of .698 for Balloon and .397 for Fish. The graphs above illustrate the impact of modulating the IT over time. The red lines in all modulation sequences show the average APA of players for one given IT during three minutes. The bold black line shows the average modulation of activity over time and the thin colored lines represent every group of children playing this modulation. In all cases the low IT level had the least APA and the high IT had the most.

Diversity of Combination of Movements

Regarding the diversity of movement, systematic observation methods using a video coding system developed by physical education experts revealed than a greater number of combinations were recorded for the Fish Game, compared with the Balloon Game. In total, 77 different movement combinations were observed for the Fish Game over ten groups compared to 48 combinations for the Balloon Game. Per group an average of 30 specific movements was observed at each session of the Fish Game, compared to 22 for the Balloon Game.